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Merge git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-2.6-fscache

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* git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-2.6-fscache: (41 commits)
  NFS: Add mount options to enable local caching on NFS
  NFS: Display local caching state
  NFS: Store pages from an NFS inode into a local cache
  NFS: Read pages from FS-Cache into an NFS inode
  NFS: nfs_readpage_async() needs to be accessible as a fallback for local caching
  NFS: Add read context retention for FS-Cache to call back with
  NFS: FS-Cache page management
  NFS: Add some new I/O counters for FS-Cache doing things for NFS
  NFS: Invalidate FsCache page flags when cache removed
  NFS: Use local disk inode cache
  NFS: Define and create inode-level cache objects
  NFS: Define and create superblock-level objects
  NFS: Define and create server-level objects
  NFS: Register NFS for caching and retrieve the top-level index
  NFS: Permit local filesystem caching to be enabled for NFS
  NFS: Add FS-Cache option bit and debug bit
  NFS: Add comment banners to some NFS functions
  FS-Cache: Make kAFS use FS-Cache
  CacheFiles: A cache that backs onto a mounted filesystem
  CacheFiles: Export things for CacheFiles
  ...
This commit is contained in:
Linus Torvalds 2009-04-03 10:07:43 -07:00
commit 3cc50ac0db
82 changed files with 15438 additions and 414 deletions
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658
Documentation/filesystems/caching/backend-api.txt Normal file
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==========================
FS-CACHE CACHE BACKEND API
==========================
The FS-Cache system provides an API by which actual caches can be supplied to
FS-Cache for it to then serve out to network filesystems and other interested
parties.
This API is declared in <linux/fscache-cache.h>.
====================================
INITIALISING AND REGISTERING A CACHE
====================================
To start off, a cache definition must be initialised and registered for each
cache the backend wants to make available. For instance, CacheFS does this in
the fill_super() operation on mounting.
The cache definition (struct fscache_cache) should be initialised by calling:
void fscache_init_cache(struct fscache_cache *cache,
struct fscache_cache_ops *ops,
const char *idfmt,
...);
Where:
(*) "cache" is a pointer to the cache definition;
(*) "ops" is a pointer to the table of operations that the backend supports on
this cache; and
(*) "idfmt" is a format and printf-style arguments for constructing a label
for the cache.
The cache should then be registered with FS-Cache by passing a pointer to the
previously initialised cache definition to:
int fscache_add_cache(struct fscache_cache *cache,
struct fscache_object *fsdef,
const char *tagname);
Two extra arguments should also be supplied:
(*) "fsdef" which should point to the object representation for the FS-Cache
master index in this cache. Netfs primary index entries will be created
here. FS-Cache keeps the caller's reference to the index object if
successful and will release it upon withdrawal of the cache.
(*) "tagname" which, if given, should be a text string naming this cache. If
this is NULL, the identifier will be used instead. For CacheFS, the
identifier is set to name the underlying block device and the tag can be
supplied by mount.
This function may return -ENOMEM if it ran out of memory or -EEXIST if the tag
is already in use. 0 will be returned on success.
=====================
UNREGISTERING A CACHE
=====================
A cache can be withdrawn from the system by calling this function with a
pointer to the cache definition:
void fscache_withdraw_cache(struct fscache_cache *cache);
In CacheFS's case, this is called by put_super().
========
SECURITY
========
The cache methods are executed one of two contexts:
(1) that of the userspace process that issued the netfs operation that caused
the cache method to be invoked, or
(2) that of one of the processes in the FS-Cache thread pool.
In either case, this may not be an appropriate context in which to access the
cache.
The calling process's fsuid, fsgid and SELinux security identities may need to
be masqueraded for the duration of the cache driver's access to the cache.
This is left to the cache to handle; FS-Cache makes no effort in this regard.
===================================
CONTROL AND STATISTICS PRESENTATION
===================================
The cache may present data to the outside world through FS-Cache's interfaces
in sysfs and procfs - the former for control and the latter for statistics.
A sysfs directory called /sys/fs/fscache/<cachetag>/ is created if CONFIG_SYSFS
is enabled. This is accessible through the kobject struct fscache_cache::kobj
and is for use by the cache as it sees fit.
========================
RELEVANT DATA STRUCTURES
========================
(*) Index/Data file FS-Cache representation cookie:
struct fscache_cookie {
struct fscache_object_def *def;
struct fscache_netfs *netfs;
void *netfs_data;
...
};
The fields that might be of use to the backend describe the object
definition, the netfs definition and the netfs's data for this cookie.
The object definition contain functions supplied by the netfs for loading
and matching index entries; these are required to provide some of the
cache operations.
(*) In-cache object representation:
struct fscache_object {
int debug_id;
enum {
FSCACHE_OBJECT_RECYCLING,
...
} state;
spinlock_t lock
struct fscache_cache *cache;
struct fscache_cookie *cookie;
...
};
Structures of this type should be allocated by the cache backend and
passed to FS-Cache when requested by the appropriate cache operation. In
the case of CacheFS, they're embedded in CacheFS's internal object
structures.
The debug_id is a simple integer that can be used in debugging messages
that refer to a particular object. In such a case it should be printed
using "OBJ%x" to be consistent with FS-Cache.
Each object contains a pointer to the cookie that represents the object it
is backing. An object should retired when put_object() is called if it is
in state FSCACHE_OBJECT_RECYCLING. The fscache_object struct should be
initialised by calling fscache_object_init(object).
(*) FS-Cache operation record:
struct fscache_operation {
atomic_t usage;
struct fscache_object *object;
unsigned long flags;
#define FSCACHE_OP_EXCLUSIVE
void (*processor)(struct fscache_operation *op);
void (*release)(struct fscache_operation *op);
...
};
FS-Cache has a pool of threads that it uses to give CPU time to the
various asynchronous operations that need to be done as part of driving
the cache. These are represented by the above structure. The processor
method is called to give the op CPU time, and the release method to get
rid of it when its usage count reaches 0.
An operation can be made exclusive upon an object by setting the
appropriate flag before enqueuing it with fscache_enqueue_operation(). If
an operation needs more processing time, it should be enqueued again.
(*) FS-Cache retrieval operation record:
struct fscache_retrieval {
struct fscache_operation op;
struct address_space *mapping;
struct list_head *to_do;
...
};
A structure of this type is allocated by FS-Cache to record retrieval and
allocation requests made by the netfs. This struct is then passed to the
backend to do the operation. The backend may get extra refs to it by
calling fscache_get_retrieval() and refs may be discarded by calling
fscache_put_retrieval().
A retrieval operation can be used by the backend to do retrieval work. To
do this, the retrieval->op.processor method pointer should be set
appropriately by the backend and fscache_enqueue_retrieval() called to
submit it to the thread pool. CacheFiles, for example, uses this to queue
page examination when it detects PG_lock being cleared.
The to_do field is an empty list available for the cache backend to use as
it sees fit.
(*) FS-Cache storage operation record:
struct fscache_storage {
struct fscache_operation op;
pgoff_t store_limit;
...
};
A structure of this type is allocated by FS-Cache to record outstanding
writes to be made. FS-Cache itself enqueues this operation and invokes
the write_page() method on the object at appropriate times to effect
storage.
================
CACHE OPERATIONS
================
The cache backend provides FS-Cache with a table of operations that can be
performed on the denizens of the cache. These are held in a structure of type:
struct fscache_cache_ops
(*) Name of cache provider [mandatory]:
const char *name
This isn't strictly an operation, but should be pointed at a string naming
the backend.
(*) Allocate a new object [mandatory]:
struct fscache_object *(*alloc_object)(struct fscache_cache *cache,
struct fscache_cookie *cookie)
This method is used to allocate a cache object representation to back a
cookie in a particular cache. fscache_object_init() should be called on
the object to initialise it prior to returning.
This function may also be used to parse the index key to be used for
multiple lookup calls to turn it into a more convenient form. FS-Cache
will call the lookup_complete() method to allow the cache to release the
form once lookup is complete or aborted.
(*) Look up and create object [mandatory]:
void (*lookup_object)(struct fscache_object *object)
This method is used to look up an object, given that the object is already
allocated and attached to the cookie. This should instantiate that object
in the cache if it can.
The method should call fscache_object_lookup_negative() as soon as
possible if it determines the object doesn't exist in the cache. If the
object is found to exist and the netfs indicates that it is valid then
fscache_obtained_object() should be called once the object is in a
position to have data stored in it. Similarly, fscache_obtained_object()
should also be called once a non-present object has been created.
If a lookup error occurs, fscache_object_lookup_error() should be called
to abort the lookup of that object.
(*) Release lookup data [mandatory]:
void (*lookup_complete)(struct fscache_object *object)
This method is called to ask the cache to release any resources it was
using to perform a lookup.
(*) Increment object refcount [mandatory]:
struct fscache_object *(*grab_object)(struct fscache_object *object)
This method is called to increment the reference count on an object. It
may fail (for instance if the cache is being withdrawn) by returning NULL.
It should return the object pointer if successful.
(*) Lock/Unlock object [mandatory]:
void (*lock_object)(struct fscache_object *object)
void (*unlock_object)(struct fscache_object *object)
These methods are used to exclusively lock an object. It must be possible
to schedule with the lock held, so a spinlock isn't sufficient.
(*) Pin/Unpin object [optional]:
int (*pin_object)(struct fscache_object *object)
void (*unpin_object)(struct fscache_object *object)
These methods are used to pin an object into the cache. Once pinned an
object cannot be reclaimed to make space. Return -ENOSPC if there's not
enough space in the cache to permit this.
(*) Update object [mandatory]:
int (*update_object)(struct fscache_object *object)
This is called to update the index entry for the specified object. The
new information should be in object->cookie->netfs_data. This can be
obtained by calling object->cookie->def->get_aux()/get_attr().
(*) Discard object [mandatory]:
void (*drop_object)(struct fscache_object *object)
This method is called to indicate that an object has been unbound from its
cookie, and that the cache should release the object's resources and
retire it if it's in state FSCACHE_OBJECT_RECYCLING.
This method should not attempt to release any references held by the
caller. The caller will invoke the put_object() method as appropriate.
(*) Release object reference [mandatory]:
void (*put_object)(struct fscache_object *object)
This method is used to discard a reference to an object. The object may
be freed when all the references to it are released.
(*) Synchronise a cache [mandatory]:
void (*sync)(struct fscache_cache *cache)
This is called to ask the backend to synchronise a cache with its backing
device.
(*) Dissociate a cache [mandatory]:
void (*dissociate_pages)(struct fscache_cache *cache)
This is called to ask a cache to perform any page dissociations as part of
cache withdrawal.
(*) Notification that the attributes on a netfs file changed [mandatory]:
int (*attr_changed)(struct fscache_object *object);
This is called to indicate to the cache that certain attributes on a netfs
file have changed (for example the maximum size a file may reach). The
cache can read these from the netfs by calling the cookie's get_attr()
method.
The cache may use the file size information to reserve space on the cache.
It should also call fscache_set_store_limit() to indicate to FS-Cache the
highest byte it's willing to store for an object.
This method may return -ve if an error occurred or the cache object cannot
be expanded. In such a case, the object will be withdrawn from service.
This operation is run asynchronously from FS-Cache's thread pool, and
storage and retrieval operations from the netfs are excluded during the
execution of this operation.
(*) Reserve cache space for an object's data [optional]:
int (*reserve_space)(struct fscache_object *object, loff_t size);
This is called to request that cache space be reserved to hold the data
for an object and the metadata used to track it. Zero size should be
taken as request to cancel a reservation.
This should return 0 if successful, -ENOSPC if there isn't enough space
available, or -ENOMEM or -EIO on other errors.
The reservation may exceed the current size of the object, thus permitting
future expansion. If the amount of space consumed by an object would
exceed the reservation, it's permitted to refuse requests to allocate
pages, but not required. An object may be pruned down to its reservation
size if larger than that already.
(*) Request page be read from cache [mandatory]:
int (*read_or_alloc_page)(struct fscache_retrieval *op,
struct page *page,
gfp_t gfp)
This is called to attempt to read a netfs page from the cache, or to
reserve a backing block if not. FS-Cache will have done as much checking
as it can before calling, but most of the work belongs to the backend.
If there's no page in the cache, then -ENODATA should be returned if the
backend managed to reserve a backing block; -ENOBUFS or -ENOMEM if it
didn't.
If there is suitable data in the cache, then a read operation should be
queued and 0 returned. When the read finishes, fscache_end_io() should be
called.
The fscache_mark_pages_cached() should be called for the page if any cache
metadata is retained. This will indicate to the netfs that the page needs
explicit uncaching. This operation takes a pagevec, thus allowing several
pages to be marked at once.
The retrieval record pointed to by op should be retained for each page
queued and released when I/O on the page has been formally ended.
fscache_get/put_retrieval() are available for this purpose.
The retrieval record may be used to get CPU time via the FS-Cache thread
pool. If this is desired, the op->op.processor should be set to point to
the appropriate processing routine, and fscache_enqueue_retrieval() should
be called at an appropriate point to request CPU time. For instance, the
retrieval routine could be enqueued upon the completion of a disk read.
The to_do field in the retrieval record is provided to aid in this.
If an I/O error occurs, fscache_io_error() should be called and -ENOBUFS
returned if possible or fscache_end_io() called with a suitable error
code..
(*) Request pages be read from cache [mandatory]:
int (*read_or_alloc_pages)(struct fscache_retrieval *op,
struct list_head *pages,
unsigned *nr_pages,
gfp_t gfp)
This is like the read_or_alloc_page() method, except it is handed a list
of pages instead of one page. Any pages on which a read operation is
started must be added to the page cache for the specified mapping and also
to the LRU. Such pages must also be removed from the pages list and
*nr_pages decremented per page.
If there was an error such as -ENOMEM, then that should be returned; else
if one or more pages couldn't be read or allocated, then -ENOBUFS should
be returned; else if one or more pages couldn't be read, then -ENODATA
should be returned. If all the pages are dispatched then 0 should be
returned.
(*) Request page be allocated in the cache [mandatory]:
int (*allocate_page)(struct fscache_retrieval *op,
struct page *page,
gfp_t gfp)
This is like the read_or_alloc_page() method, except that it shouldn't
read from the cache, even if there's data there that could be retrieved.
It should, however, set up any internal metadata required such that
the write_page() method can write to the cache.
If there's no backing block available, then -ENOBUFS should be returned
(or -ENOMEM if there were other problems). If a block is successfully
allocated, then the netfs page should be marked and 0 returned.
(*) Request pages be allocated in the cache [mandatory]:
int (*allocate_pages)(struct fscache_retrieval *op,
struct list_head *pages,
unsigned *nr_pages,
gfp_t gfp)
This is an multiple page version of the allocate_page() method. pages and
nr_pages should be treated as for the read_or_alloc_pages() method.
(*) Request page be written to cache [mandatory]:
int (*write_page)(struct fscache_storage *op,
struct page *page);
This is called to write from a page on which there was a previously
successful read_or_alloc_page() call or similar. FS-Cache filters out
pages that don't have mappings.
This method is called asynchronously from the FS-Cache thread pool. It is
not required to actually store anything, provided -ENODATA is then
returned to the next read of this page.
If an error occurred, then a negative error code should be returned,
otherwise zero should be returned. FS-Cache will take appropriate action
in response to an error, such as withdrawing this object.
If this method returns success then FS-Cache will inform the netfs
appropriately.
(*) Discard retained per-page metadata [mandatory]:
void (*uncache_page)(struct fscache_object *object, struct page *page)
This is called when a netfs page is being evicted from the pagecache. The
cache backend should tear down any internal representation or tracking it
maintains for this page.
==================
FS-CACHE UTILITIES
==================
FS-Cache provides some utilities that a cache backend may make use of:
(*) Note occurrence of an I/O error in a cache:
void fscache_io_error(struct fscache_cache *cache)
This tells FS-Cache that an I/O error occurred in the cache. After this
has been called, only resource dissociation operations (object and page
release) will be passed from the netfs to the cache backend for the
specified cache.
This does not actually withdraw the cache. That must be done separately.
(*) Invoke the retrieval I/O completion function:
void fscache_end_io(struct fscache_retrieval *op, struct page *page,
int error);
This is called to note the end of an attempt to retrieve a page. The
error value should be 0 if successful and an error otherwise.
(*) Set highest store limit:
void fscache_set_store_limit(struct fscache_object *object,
loff_t i_size);
This sets the limit FS-Cache imposes on the highest byte it's willing to
try and store for a netfs. Any page over this limit is automatically
rejected by fscache_read_alloc_page() and co with -ENOBUFS.
(*) Mark pages as being cached:
void fscache_mark_pages_cached(struct fscache_retrieval *op,
struct pagevec *pagevec);
This marks a set of pages as being cached. After this has been called,
the netfs must call fscache_uncache_page() to unmark the pages.
(*) Perform coherency check on an object:
enum fscache_checkaux fscache_check_aux(struct fscache_object *object,
const void *data,
uint16_t datalen);
This asks the netfs to perform a coherency check on an object that has
just been looked up. The cookie attached to the object will determine the
netfs to use. data and datalen should specify where the auxiliary data
retrieved from the cache can be found.
One of three values will be returned:
(*) FSCACHE_CHECKAUX_OKAY
The coherency data indicates the object is valid as is.
(*) FSCACHE_CHECKAUX_NEEDS_UPDATE
The coherency data needs updating, but otherwise the object is
valid.
(*) FSCACHE_CHECKAUX_OBSOLETE
The coherency data indicates that the object is obsolete and should
be discarded.
(*) Initialise a freshly allocated object:
void fscache_object_init(struct fscache_object *object);
This initialises all the fields in an object representation.
(*) Indicate the destruction of an object:
void fscache_object_destroyed(struct fscache_cache *cache);
This must be called to inform FS-Cache that an object that belonged to a
cache has been destroyed and deallocated. This will allow continuation
of the cache withdrawal process when it is stopped pending destruction of
all the objects.
(*) Indicate negative lookup on an object:
void fscache_object_lookup_negative(struct fscache_object *object);
This is called to indicate to FS-Cache that a lookup process for an object
found a negative result.
This changes the state of an object to permit reads pending on lookup
completion to go off and start fetching data from the netfs server as it's
known at this point that there can't be any data in the cache.
This may be called multiple times on an object. Only the first call is
significant - all subsequent calls are ignored.
(*) Indicate an object has been obtained:
void fscache_obtained_object(struct fscache_object *object);
This is called to indicate to FS-Cache that a lookup process for an object
produced a positive result, or that an object was created. This should
only be called once for any particular object.
This changes the state of an object to indicate:
(1) if no call to fscache_object_lookup_negative() has been made on
this object, that there may be data available, and that reads can
now go and look for it; and
(2) that writes may now proceed against this object.
(*) Indicate that object lookup failed:
void fscache_object_lookup_error(struct fscache_object *object);
This marks an object as having encountered a fatal error (usually EIO)
and causes it to move into a state whereby it will be withdrawn as soon
as possible.
(*) Get and release references on a retrieval record:
void fscache_get_retrieval(struct fscache_retrieval *op);
void fscache_put_retrieval(struct fscache_retrieval *op);
These two functions are used to retain a retrieval record whilst doing
asynchronous data retrieval and block allocation.
(*) Enqueue a retrieval record for processing.
void fscache_enqueue_retrieval(struct fscache_retrieval *op);
This enqueues a retrieval record for processing by the FS-Cache thread
pool. One of the threads in the pool will invoke the retrieval record's
op->op.processor callback function. This function may be called from
within the callback function.
(*) List of object state names:
const char *fscache_object_states[];
For debugging purposes, this may be used to turn the state that an object
is in into a text string for display purposes.

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===============================================
CacheFiles: CACHE ON ALREADY MOUNTED FILESYSTEM
===============================================
Contents:
(*) Overview.
(*) Requirements.
(*) Configuration.
(*) Starting the cache.
(*) Things to avoid.
(*) Cache culling.
(*) Cache structure.
(*) Security model and SELinux.
(*) A note on security.
(*) Statistical information.
(*) Debugging.
========
OVERVIEW
========
CacheFiles is a caching backend that's meant to use as a cache a directory on
an already mounted filesystem of a local type (such as Ext3).
CacheFiles uses a userspace daemon to do some of the cache management - such as
reaping stale nodes and culling. This is called cachefilesd and lives in
/sbin.
The filesystem and data integrity of the cache are only as good as those of the
filesystem providing the backing services. Note that CacheFiles does not
attempt to journal anything since the journalling interfaces of the various
filesystems are very specific in nature.
CacheFiles creates a misc character device - "/dev/cachefiles" - that is used
to communication with the daemon. Only one thing may have this open at once,
and whilst it is open, a cache is at least partially in existence. The daemon
opens this and sends commands down it to control the cache.
CacheFiles is currently limited to a single cache.
CacheFiles attempts to maintain at least a certain percentage of free space on
the filesystem, shrinking the cache by culling the objects it contains to make
space if necessary - see the "Cache Culling" section. This means it can be
placed on the same medium as a live set of data, and will expand to make use of
spare space and automatically contract when the set of data requires more
space.
============
REQUIREMENTS
============
The use of CacheFiles and its daemon requires the following features to be
available in the system and in the cache filesystem:
- dnotify.
- extended attributes (xattrs).
- openat() and friends.
- bmap() support on files in the filesystem (FIBMAP ioctl).
- The use of bmap() to detect a partial page at the end of the file.
It is strongly recommended that the "dir_index" option is enabled on Ext3
filesystems being used as a cache.
=============
CONFIGURATION
=============
The cache is configured by a script in /etc/cachefilesd.conf. These commands
set up cache ready for use. The following script commands are available:
(*) brun <N>%
(*) bcull <N>%
(*) bstop <N>%
(*) frun <N>%
(*) fcull <N>%
(*) fstop <N>%
Configure the culling limits. Optional. See the section on culling
The defaults are 7% (run), 5% (cull) and 1% (stop) respectively.
The commands beginning with a 'b' are file space (block) limits, those
beginning with an 'f' are file count limits.
(*) dir <path>
Specify the directory containing the root of the cache. Mandatory.
(*) tag <name>
Specify a tag to FS-Cache to use in distinguishing multiple caches.
Optional. The default is "CacheFiles".
(*) debug <mask>
Specify a numeric bitmask to control debugging in the kernel module.
Optional. The default is zero (all off). The following values can be
OR'd into the mask to collect various information:
1 Turn on trace of function entry (_enter() macros)
2 Turn on trace of function exit (_leave() macros)
4 Turn on trace of internal debug points (_debug())
This mask can also be set through sysfs, eg:
echo 5 >/sys/modules/cachefiles/parameters/debug
==================
STARTING THE CACHE
==================
The cache is started by running the daemon. The daemon opens the cache device,
configures the cache and tells it to begin caching. At that point the cache
binds to fscache and the cache becomes live.
The daemon is run as follows:
/sbin/cachefilesd [-d]* [-s] [-n] [-f <configfile>]
The flags are:
(*) -d
Increase the debugging level. This can be specified multiple times and
is cumulative with itself.
(*) -s
Send messages to stderr instead of syslog.
(*) -n
Don't daemonise and go into background.
(*) -f <configfile>
Use an alternative configuration file rather than the default one.
===============
THINGS TO AVOID
===============
Do not mount other things within the cache as this will cause problems. The
kernel module contains its own very cut-down path walking facility that ignores
mountpoints, but the daemon can't avoid them.
Do not create, rename or unlink files and directories in the cache whilst the
cache is active, as this may cause the state to become uncertain.
Renaming files in the cache might make objects appear to be other objects (the
filename is part of the lookup key).
Do not change or remove the extended attributes attached to cache files by the
cache as this will cause the cache state management to get confused.
Do not create files or directories in the cache, lest the cache get confused or
serve incorrect data.
Do not chmod files in the cache. The module creates things with minimal
permissions to prevent random users being able to access them directly.
=============
CACHE CULLING
=============
The cache may need culling occasionally to make space. This involves
discarding objects from the cache that have been used less recently than
anything else. Culling is based on the access time of data objects. Empty
directories are culled if not in use.
Cache culling is done on the basis of the percentage of blocks and the
percentage of files available in the underlying filesystem. There are six
"limits":
(*) brun
(*) frun
If the amount of free space and the number of available files in the cache
rises above both these limits, then culling is turned off.
(*) bcull
(*) fcull
If the amount of available space or the number of available files in the
cache falls below either of these limits, then culling is started.
(*) bstop
(*) fstop
If the amount of available space or the number of available files in the
cache falls below either of these limits, then no further allocation of
disk space or files is permitted until culling has raised things above
these limits again.
These must be configured thusly:
0 <= bstop < bcull < brun < 100
0 <= fstop < fcull < frun < 100
Note that these are percentages of available space and available files, and do
_not_ appear as 100 minus the percentage displayed by the "df" program.
The userspace daemon scans the cache to build up a table of cullable objects.
These are then culled in least recently used order. A new scan of the cache is
started as soon as space is made in the table. Objects will be skipped if
their atimes have changed or if the kernel module says it is still using them.
===============
CACHE STRUCTURE
===============
The CacheFiles module will create two directories in the directory it was
given:
(*) cache/
(*) graveyard/
The active cache objects all reside in the first directory. The CacheFiles
kernel module moves any retired or culled objects that it can't simply unlink
to the graveyard from which the daemon will actually delete them.
The daemon uses dnotify to monitor the graveyard directory, and will delete
anything that appears therein.
The module represents index objects as directories with the filename "I..." or
"J...". Note that the "cache/" directory is itself a special index.
Data objects are represented as files if they have no children, or directories
if they do. Their filenames all begin "D..." or "E...". If represented as a
directory, data objects will have a file in the directory called "data" that
actually holds the data.
Special objects are similar to data objects, except their filenames begin
"S..." or "T...".
If an object has children, then it will be represented as a directory.
Immediately in the representative directory are a collection of directories
named for hash values of the child object keys with an '@' prepended. Into
this directory, if possible, will be placed the representations of the child
objects:
INDEX INDEX INDEX DATA FILES
========= ========== ================================= ================
cache/@4a/I03nfs/@30/Ji000000000000000--fHg8hi8400
cache/@4a/I03nfs/@30/Ji000000000000000--fHg8hi8400/@75/Es0g000w...DB1ry
cache/@4a/I03nfs/@30/Ji000000000000000--fHg8hi8400/@75/Es0g000w...N22ry
cache/@4a/I03nfs/@30/Ji000000000000000--fHg8hi8400/@75/Es0g000w...FP1ry
If the key is so long that it exceeds NAME_MAX with the decorations added on to
it, then it will be cut into pieces, the first few of which will be used to
make a nest of directories, and the last one of which will be the objects
inside the last directory. The names of the intermediate directories will have
'+' prepended:
J1223/@23/+xy...z/+kl...m/Epqr
Note that keys are raw data, and not only may they exceed NAME_MAX in size,
they may also contain things like '/' and NUL characters, and so they may not
be suitable for turning directly into a filename.
To handle this, CacheFiles will use a suitably printable filename directly and
"base-64" encode ones that aren't directly suitable. The two versions of
object filenames indicate the encoding:
OBJECT TYPE PRINTABLE ENCODED
=============== =============== ===============
Index "I..." "J..."
Data "D..." "E..."
Special "S..." "T..."
Intermediate directories are always "@" or "+" as appropriate.
Each object in the cache has an extended attribute label that holds the object
type ID (required to distinguish special objects) and the auxiliary data from
the netfs. The latter is used to detect stale objects in the cache and update
or retire them.
Note that CacheFiles will erase from the cache any file it doesn't recognise or
any file of an incorrect type (such as a FIFO file or a device file).
==========================
SECURITY MODEL AND SELINUX
==========================
CacheFiles is implemented to deal properly with the LSM security features of
the Linux kernel and the SELinux facility.
One of the problems that CacheFiles faces is that it is generally acting on
behalf of a process, and running in that process's context, and that includes a
security context that is not appropriate for accessing the cache - either
because the files in the cache are inaccessible to that process, or because if
the process creates a file in the cache, that file may be inaccessible to other
processes.
The way CacheFiles works is to temporarily change the security context (fsuid,
fsgid and actor security label) that the process acts as - without changing the
security context of the process when it the target of an operation performed by
some other process (so signalling and suchlike still work correctly).
When the CacheFiles module is asked to bind to its cache, it:
(1) Finds the security label attached to the root cache directory and uses
that as the security label with which it will create files. By default,
this is:
cachefiles_var_t
(2) Finds the security label of the process which issued the bind request
(presumed to be the cachefilesd daemon), which by default will be:
cachefilesd_t
and asks LSM to supply a security ID as which it should act given the
daemon's label. By default, this will be:
cachefiles_kernel_t
SELinux transitions the daemon's security ID to the module's security ID
based on a rule of this form in the policy.
type_transition <daemon's-ID> kernel_t : process <module's-ID>;
For instance:
type_transition cachefilesd_t kernel_t : process cachefiles_kernel_t;
The module's security ID gives it permission to create, move and remove files
and directories in the cache, to find and access directories and files in the
cache, to set and access extended attributes on cache objects, and to read and
write files in the cache.
The daemon's security ID gives it only a very restricted set of permissions: it
may scan directories, stat files and erase files and directories. It may
not read or write files in the cache, and so it is precluded from accessing the
data cached therein; nor is it permitted to create new files in the cache.
There are policy source files available in:
http://people.redhat.com/~dhowells/fscache/cachefilesd-0.8.tar.bz2
and later versions. In that tarball, see the files:
cachefilesd.te
cachefilesd.fc
cachefilesd.if
They are built and installed directly by the RPM.
If a non-RPM based system is being used, then copy the above files to their own
directory and run:
make -f /usr/share/selinux/devel/Makefile
semodule -i cachefilesd.pp
You will need checkpolicy and selinux-policy-devel installed prior to the
build.
By default, the cache is located in /var/fscache, but if it is desirable that
it should be elsewhere, than either the above policy files must be altered, or
an auxiliary policy must be installed to label the alternate location of the
cache.
For instructions on how to add an auxiliary policy to enable the cache to be
located elsewhere when SELinux is in enforcing mode, please see:
/usr/share/doc/cachefilesd-*/move-cache.txt
When the cachefilesd rpm is installed; alternatively, the document can be found
in the sources.
==================
A NOTE ON SECURITY
==================
CacheFiles makes use of the split security in the task_struct. It allocates
its own task_security structure, and redirects current->act_as to point to it
when it acts on behalf of another process, in that process's context.
The reason it does this is that it calls vfs_mkdir() and suchlike rather than
bypassing security and calling inode ops directly. Therefore the VFS and LSM
may deny the CacheFiles access to the cache data because under some
circumstances the caching code is running in the security context of whatever
process issued the original syscall on the netfs.
Furthermore, should CacheFiles create a file or directory, the security
parameters with that object is created (UID, GID, security label) would be
derived from that process that issued the system call, thus potentially
preventing other processes from accessing the cache - including CacheFiles's
cache management daemon (cachefilesd).
What is required is to temporarily override the security of the process that
issued the system call. We can't, however, just do an in-place change of the
security data as that affects the process as an object, not just as a subject.
This means it may lose signals or ptrace events for example, and affects what
the process looks like in /proc.
So CacheFiles makes use of a logical split in the security between the
objective security (task->sec) and the subjective security (task->act_as). The
objective security holds the intrinsic security properties of a process and is
never overridden. This is what appears in /proc, and is what is used when a
process is the target of an operation by some other process (SIGKILL for
example).
The subjective security holds the active security properties of a process, and
may be overridden. This is not seen externally, and is used whan a process
acts upon another object, for example SIGKILLing another process or opening a
file.
LSM hooks exist that allow SELinux (or Smack or whatever) to reject a request
for CacheFiles to run in a context of a specific security label, or to create
files and directories with another security label.
=======================
STATISTICAL INFORMATION
=======================
If FS-Cache is compiled with the following option enabled:
CONFIG_CACHEFILES_HISTOGRAM=y
then it will gather certain statistics and display them through a proc file.
(*) /proc/fs/cachefiles/histogram
cat /proc/fs/cachefiles/histogram
JIFS SECS LOOKUPS MKDIRS CREATES
===== ===== ========= ========= =========
This shows the breakdown of the number of times each amount of time
between 0 jiffies and HZ-1 jiffies a variety of tasks took to run. The
columns are as follows:
COLUMN TIME MEASUREMENT
======= =======================================================
LOOKUPS Length of time to perform a lookup on the backing fs
MKDIRS Length of time to perform a mkdir on the backing fs
CREATES Length of time to perform a create on the backing fs
Each row shows the number of events that took a particular range of times.
Each step is 1 jiffy in size. The JIFS column indicates the particular
jiffy range covered, and the SECS field the equivalent number of seconds.
=========
DEBUGGING
=========
If CONFIG_CACHEFILES_DEBUG is enabled, the CacheFiles facility can have runtime
debugging enabled by adjusting the value in:
/sys/module/cachefiles/parameters/debug
This is a bitmask of debugging streams to enable:
BIT VALUE STREAM POINT
======= ======= =============================== =======================
0 1 General Function entry trace
1 2 Function exit trace
2 4 General
The appropriate set of values should be OR'd together and the result written to
the control file. For example:
echo $((1|4|8)) >/sys/module/cachefiles/parameters/debug
will turn on all function entry debugging.

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==========================
General Filesystem Caching
==========================
========
OVERVIEW
========
This facility is a general purpose cache for network filesystems, though it
could be used for caching other things such as ISO9660 filesystems too.
FS-Cache mediates between cache backends (such as CacheFS) and network
filesystems:
+---------+
| | +--------------+
| NFS |--+ | |
| | | +-->| CacheFS |
+---------+ | +----------+ | | /dev/hda5 |
| | | | +--------------+
+---------+ +-->| | |
| | | |--+
| AFS |----->| FS-Cache |
| | | |--+
+---------+ +-->| | |
| | | | +--------------+
+---------+ | +----------+ | | |
| | | +-->| CacheFiles |
| ISOFS |--+ | /var/cache |
| | +--------------+
+---------+
Or to look at it another way, FS-Cache is a module that provides a caching
facility to a network filesystem such that the cache is transparent to the
user:
+---------+
| |
| Server |
| |
+---------+
| NETWORK
~~~~~|~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
|
| +----------+
V | |
+---------+ | |
| | | |
| NFS |----->| FS-Cache |
| | | |--+
+---------+ | | | +--------------+ +--------------+
| | | | | | | |
V +----------+ +-->| CacheFiles |-->| Ext3 |
+---------+ | /var/cache | | /dev/sda6 |
| | +--------------+ +--------------+
| VFS | ^ ^
| | | |
+---------+ +--------------+ |
| KERNEL SPACE | |
~~~~~|~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~|~~~~~~|~~~~
| USER SPACE | |
V | |
+---------+ +--------------+
| | | |
| Process | | cachefilesd |
| | | |
+---------+ +--------------+
FS-Cache does not follow the idea of completely loading every netfs file
opened in its entirety into a cache before permitting it to be accessed and
then serving the pages out of that cache rather than the netfs inode because:
(1) It must be practical to operate without a cache.
(2) The size of any accessible file must not be limited to the size of the
cache.
(3) The combined size of all opened files (this includes mapped libraries)
must not be limited to the size of the cache.
(4) The user should not be forced to download an entire file just to do a
one-off access of a small portion of it (such as might be done with the
"file" program).
It instead serves the cache out in PAGE_SIZE chunks as and when requested by
the netfs('s) using it.
FS-Cache provides the following facilities:
(1) More than one cache can be used at once. Caches can be selected
explicitly by use of tags.
(2) Caches can be added / removed at any time.
(3) The netfs is provided with an interface that allows either party to
withdraw caching facilities from a file (required for (2)).
(4) The interface to the netfs returns as few errors as possible, preferring
rather to let the netfs remain oblivious.
(5) Cookies are used to represent indices, files and other objects to the
netfs. The simplest cookie is just a NULL pointer - indicating nothing
cached there.
(6) The netfs is allowed to propose - dynamically - any index hierarchy it
desires, though it must be aware that the index search function is
recursive, stack space is limited, and indices can only be children of
indices.
(7) Data I/O is done direct to and from the netfs's pages. The netfs
indicates that page A is at index B of the data-file represented by cookie
C, and that it should be read or written. The cache backend may or may
not start I/O on that page, but if it does, a netfs callback will be
invoked to indicate completion. The I/O may be either synchronous or
asynchronous.
(8) Cookies can be "retired" upon release. At this point FS-Cache will mark
them as obsolete and the index hierarchy rooted at that point will get
recycled.
(9) The netfs provides a "match" function for index searches. In addition to
saying whether a match was made or not, this can also specify that an
entry should be updated or deleted.
(10) As much as possible is done asynchronously.
FS-Cache maintains a virtual indexing tree in which all indices, files, objects
and pages are kept. Bits of this tree may actually reside in one or more
caches.
FSDEF
|
+------------------------------------+
| |
NFS AFS
| |
+--------------------------+ +-----------+
| | | |
homedir mirror afs.org redhat.com
| | |
+------------+ +---------------+ +----------+
| | | | | |
00001 00002 00007 00125 vol00001 vol00002
| | | | |
+---+---+ +-----+ +---+ +------+------+ +-----+----+
| | | | | | | | | | | | |
PG0 PG1 PG2 PG0 XATTR PG0 PG1 DIRENT DIRENT DIRENT R/W R/O Bak
| |
PG0 +-------+
| |
00001 00003
|
+---+---+
| | |
PG0 PG1 PG2
In the example above, you can see two netfs's being backed: NFS and AFS. These
have different index hierarchies:
(*) The NFS primary index contains per-server indices. Each server index is
indexed by NFS file handles to get data file objects. Each data file
objects can have an array of pages, but may also have further child
objects, such as extended attributes and directory entries. Extended
attribute objects themselves have page-array contents.
(*) The AFS primary index contains per-cell indices. Each cell index contains
per-logical-volume indices. Each of volume index contains up to three
indices for the read-write, read-only and backup mirrors of those volumes.
Each of these contains vnode data file objects, each of which contains an
array of pages.
The very top index is the FS-Cache master index in which individual netfs's
have entries.
Any index object may reside in more than one cache, provided it only has index
children. Any index with non-index object children will be assumed to only
reside in one cache.
The netfs API to FS-Cache can be found in:
Documentation/filesystems/caching/netfs-api.txt
The cache backend API to FS-Cache can be found in:
Documentation/filesystems/caching/backend-api.txt
A description of the internal representations and object state machine can be
found in:
Documentation/filesystems/caching/object.txt
=======================
STATISTICAL INFORMATION
=======================
If FS-Cache is compiled with the following options enabled:
CONFIG_FSCACHE_STATS=y
CONFIG_FSCACHE_HISTOGRAM=y
then it will gather certain statistics and display them through a number of
proc files.
(*) /proc/fs/fscache/stats
This shows counts of a number of events that can happen in FS-Cache:
CLASS EVENT MEANING
======= ======= =======================================================
Cookies idx=N Number of index cookies allocated
dat=N Number of data storage cookies allocated
spc=N Number of special cookies allocated
Objects alc=N Number of objects allocated
nal=N Number of object allocation failures
avl=N Number of objects that reached the available state
ded=N Number of objects that reached the dead state
ChkAux non=N Number of objects that didn't have a coherency check
ok=N Number of objects that passed a coherency check
upd=N Number of objects that needed a coherency data update
obs=N Number of objects that were declared obsolete
Pages mrk=N Number of pages marked as being cached
unc=N Number of uncache page requests seen
Acquire n=N Number of acquire cookie requests seen
nul=N Number of acq reqs given a NULL parent
noc=N Number of acq reqs rejected due to no cache available
ok=N Number of acq reqs succeeded
nbf=N Number of acq reqs rejected due to error
oom=N Number of acq reqs failed on ENOMEM
Lookups n=N Number of lookup calls made on cache backends
neg=N Number of negative lookups made
pos=N Number of positive lookups made
crt=N Number of objects created by lookup
Updates n=N Number of update cookie requests seen
nul=N Number of upd reqs given a NULL parent
run=N Number of upd reqs granted CPU time
Relinqs n=N Number of relinquish cookie requests seen
nul=N Number of rlq reqs given a NULL parent
wcr=N Number of rlq reqs waited on completion of creation
AttrChg n=N Number of attribute changed requests seen
ok=N Number of attr changed requests queued
nbf=N Number of attr changed rejected -ENOBUFS
oom=N Number of attr changed failed -ENOMEM
run=N Number of attr changed ops given CPU time
Allocs n=N Number of allocation requests seen
ok=N Number of successful alloc reqs
wt=N Number of alloc reqs that waited on lookup completion
nbf=N Number of alloc reqs rejected -ENOBUFS
ops=N Number of alloc reqs submitted
owt=N Number of alloc reqs waited for CPU time
Retrvls n=N Number of retrieval (read) requests seen
ok=N Number of successful retr reqs
wt=N Number of retr reqs that waited on lookup completion
nod=N Number of retr reqs returned -ENODATA
nbf=N Number of retr reqs rejected -ENOBUFS
int=N Number of retr reqs aborted -ERESTARTSYS
oom=N Number of retr reqs failed -ENOMEM
ops=N Number of retr reqs submitted
owt=N Number of retr reqs waited for CPU time
Stores n=N Number of storage (write) requests seen
ok=N Number of successful store reqs
agn=N Number of store reqs on a page already pending storage
nbf=N Number of store reqs rejected -ENOBUFS
oom=N Number of store reqs failed -ENOMEM
ops=N Number of store reqs submitted
run=N Number of store reqs granted CPU time
Ops pend=N Number of times async ops added to pending queues
run=N Number of times async ops given CPU time
enq=N Number of times async ops queued for processing
dfr=N Number of async ops queued for deferred release
rel=N Number of async ops released
gc=N Number of deferred-release async ops garbage collected
(*) /proc/fs/fscache/histogram
cat /proc/fs/fscache/histogram
JIFS SECS OBJ INST OP RUNS OBJ RUNS RETRV DLY RETRIEVLS
===== ===== ========= ========= ========= ========= =========
This shows the breakdown of the number of times each amount of time
between 0 jiffies and HZ-1 jiffies a variety of tasks took to run. The
columns are as follows:
COLUMN TIME MEASUREMENT
======= =======================================================
OBJ INST Length of time to instantiate an object
OP RUNS Length of time a call to process an operation took
OBJ RUNS Length of time a call to process an object event took
RETRV DLY Time between an requesting a read and lookup completing
RETRIEVLS Time between beginning and end of a retrieval
Each row shows the number of events that took a particular range of times.
Each step is 1 jiffy in size. The JIFS column indicates the particular
jiffy range covered, and the SECS field the equivalent number of seconds.
=========
DEBUGGING
=========
If CONFIG_FSCACHE_DEBUG is enabled, the FS-Cache facility can have runtime
debugging enabled by adjusting the value in:
/sys/module/fscache/parameters/debug
This is a bitmask of debugging streams to enable:
BIT VALUE STREAM POINT
======= ======= =============================== =======================
0 1 Cache management Function entry trace
1 2 Function exit trace
2 4 General
3 8 Cookie management Function entry trace
4 16 Function exit trace
5 32 General
6 64 Page handling Function entry trace
7 128 Function exit trace
8 256 General
9 512 Operation management Function entry trace
10 1024 Function exit trace
11 2048 General
The appropriate set of values should be OR'd together and the result written to
the control file. For example:
echo $((1|8|64)) >/sys/module/fscache/parameters/debug
will turn on all function entry debugging.

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===============================
FS-CACHE NETWORK FILESYSTEM API
===============================
There's an API by which a network filesystem can make use of the FS-Cache
facilities. This is based around a number of principles:
(1) Caches can store a number of different object types. There are two main
object types: indices and files. The first is a special type used by
FS-Cache to make finding objects faster and to make retiring of groups of
objects easier.
(2) Every index, file or other object is represented by a cookie. This cookie
may or may not have anything associated with it, but the netfs doesn't
need to care.
(3) Barring the top-level index (one entry per cached netfs), the index
hierarchy for each netfs is structured according the whim of the netfs.
This API is declared in <linux/fscache.h>.
This document contains the following sections:
(1) Network filesystem definition
(2) Index definition
(3) Object definition
(4) Network filesystem (un)registration
(5) Cache tag lookup
(6) Index registration
(7) Data file registration
(8) Miscellaneous object registration
(9) Setting the data file size
(10) Page alloc/read/write
(11) Page uncaching
(12) Index and data file update
(13) Miscellaneous cookie operations
(14) Cookie unregistration
(15) Index and data file invalidation
(16) FS-Cache specific page flags.
=============================
NETWORK FILESYSTEM DEFINITION
=============================
FS-Cache needs a description of the network filesystem. This is specified
using a record of the following structure:
struct fscache_netfs {
uint32_t version;
const char *name;
struct fscache_cookie *primary_index;
...
};
This first two fields should be filled in before registration, and the third
will be filled in by the registration function; any other fields should just be
ignored and are for internal use only.
The fields are:
(1) The name of the netfs (used as the key in the toplevel index).
(2) The version of the netfs (if the name matches but the version doesn't, the
entire in-cache hierarchy for this netfs will be scrapped and begun
afresh).
(3) The cookie representing the primary index will be allocated according to
another parameter passed into the registration function.
For example, kAFS (linux/fs/afs/) uses the following definitions to describe
itself:
struct fscache_netfs afs_cache_netfs = {
.version = 0,
.name = "afs",
};
================
INDEX DEFINITION
================
Indices are used for two purposes:
(1) To aid the finding of a file based on a series of keys (such as AFS's
"cell", "volume ID", "vnode ID").
(2) To make it easier to discard a subset of all the files cached based around
a particular key - for instance to mirror the removal of an AFS volume.
However, since it's unlikely that any two netfs's are going to want to define
their index hierarchies in quite the same way, FS-Cache tries to impose as few
restraints as possible on how an index is structured and where it is placed in
the tree. The netfs can even mix indices and data files at the same level, but
it's not recommended.
Each index entry consists of a key of indeterminate length plus some auxilliary
data, also of indeterminate length.
There are some limits on indices:
(1) Any index containing non-index objects should be restricted to a single
cache. Any such objects created within an index will be created in the
first cache only. The cache in which an index is created can be
controlled by cache tags (see below).
(2) The entry data must be atomically journallable, so it is limited to about
400 bytes at present. At least 400 bytes will be available.
(3) The depth of the index tree should be judged with care as the search
function is recursive. Too many layers will run the kernel out of stack.
=================
OBJECT DEFINITION
=================
To define an object, a structure of the following type should be filled out:
struct fscache_cookie_def
{
uint8_t name[16];
uint8_t type;
struct fscache_cache_tag *(*select_cache)(
const void *parent_netfs_data,
const void *cookie_netfs_data);
uint16_t (*get_key)(const void *cookie_netfs_data,
void *buffer,
uint16_t bufmax);
void (*get_attr)(const void *cookie_netfs_data,
uint64_t *size);
uint16_t (*get_aux)(const void *cookie_netfs_data,
void *buffer,
uint16_t bufmax);
enum fscache_checkaux (*check_aux)(void *cookie_netfs_data,
const void *data,
uint16_t datalen);
void (*get_context)(void *cookie_netfs_data, void *context);
void (*put_context)(void *cookie_netfs_data, void *context);
void (*mark_pages_cached)(void *cookie_netfs_data,
struct address_space *mapping,
struct pagevec *cached_pvec);
void (*now_uncached)(void *cookie_netfs_data);
};
This has the following fields:
(1) The type of the object [mandatory].
This is one of the following values:
(*) FSCACHE_COOKIE_TYPE_INDEX
This defines an index, which is a special FS-Cache type.
(*) FSCACHE_COOKIE_TYPE_DATAFILE
This defines an ordinary data file.
(*) Any other value between 2 and 255
This defines an extraordinary object such as an XATTR.
(2) The name of the object type (NUL terminated unless all 16 chars are used)
[optional].
(3) A function to select the cache in which to store an index [optional].
This function is invoked when an index needs to be instantiated in a cache
during the instantiation of a non-index object. Only the immediate index
parent for the non-index object will be queried. Any indices above that
in the hierarchy may be stored in multiple caches. This function does not
need to be supplied for any non-index object or any index that will only
have index children.
If this function is not supplied or if it returns NULL then the first
cache in the parent's list will be chosed, or failing that, the first
cache in the master list.
(4) A function to retrieve an object's key from the netfs [mandatory].
This function will be called with the netfs data that was passed to the
cookie acquisition function and the maximum length of key data that it may
provide. It should write the required key data into the given buffer and
return the quantity it wrote.
(5) A function to retrieve attribute data from the netfs [optional].
This function will be called with the netfs data that was passed to the
cookie acquisition function. It should return the size of the file if
this is a data file. The size may be used to govern how much cache must
be reserved for this file in the cache.
If the function is absent, a file size of 0 is assumed.
(6) A function to retrieve auxilliary data from the netfs [optional].
This function will be called with the netfs data that was passed to the
cookie acquisition function and the maximum length of auxilliary data that
it may provide. It should write the auxilliary data into the given buffer
and return the quantity it wrote.
If this function is absent, the auxilliary data length will be set to 0.
The length of the auxilliary data buffer may be dependent on the key
length. A netfs mustn't rely on being able to provide more than 400 bytes
for both.
(7) A function to check the auxilliary data [optional].
This function will be called to check that a match found in the cache for
this object is valid. For instance with AFS it could check the auxilliary
data against the data version number returned by the server to determine
whether the index entry in a cache is still valid.
If this function is absent, it will be assumed that matching objects in a
cache are always valid.
If present, the function should return one of the following values:
(*) FSCACHE_CHECKAUX_OKAY - the entry is okay as is
(*) FSCACHE_CHECKAUX_NEEDS_UPDATE - the entry requires update
(*) FSCACHE_CHECKAUX_OBSOLETE - the entry should be deleted
This function can also be used to extract data from the auxilliary data in
the cache and copy it into the netfs's structures.
(8) A pair of functions to manage contexts for the completion callback
[optional].
The cache read/write functions are passed a context which is then passed
to the I/O completion callback function. To ensure this context remains
valid until after the I/O completion is called, two functions may be
provided: one to get an extra reference on the context, and one to drop a
reference to it.
If the context is not used or is a type of object that won't go out of
scope, then these functions are not required. These functions are not
required for indices as indices may not contain data. These functions may
be called in interrupt context and so may not sleep.
(9) A function to mark a page as retaining cache metadata [optional].
This is called by the cache to indicate that it is retaining in-memory
information for this page and that the netfs should uncache the page when
it has finished. This does not indicate whether there's data on the disk
or not. Note that several pages at once may be presented for marking.
The PG_fscache bit is set on the pages before this function would be
called, so the function need not be provided if this is sufficient.
This function is not required for indices as they're not permitted data.
(10) A function to unmark all the pages retaining cache metadata [mandatory].
This is called by FS-Cache to indicate that a backing store is being
unbound from a cookie and that all the marks on the pages should be
cleared to prevent confusion. Note that the cache will have torn down all
its tracking information so that the pages don't need to be explicitly
uncached.
This function is not required for indices as they're not permitted data.
===================================
NETWORK FILESYSTEM (UN)REGISTRATION
===================================
The first step is to declare the network filesystem to the cache. This also
involves specifying the layout of the primary index (for AFS, this would be the
"cell" level).
The registration function is:
int fscache_register_netfs(struct fscache_netfs *netfs);
It just takes a pointer to the netfs definition. It returns 0 or an error as
appropriate.
For kAFS, registration is done as follows:
ret = fscache_register_netfs(&afs_cache_netfs);
The last step is, of course, unregistration:
void fscache_unregister_netfs(struct fscache_netfs *netfs);
================
CACHE TAG LOOKUP
================
FS-Cache permits the use of more than one cache. To permit particular index
subtrees to be bound to particular caches, the second step is to look up cache
representation tags. This step is optional; it can be left entirely up to
FS-Cache as to which cache should be used. The problem with doing that is that
FS-Cache will always pick the first cache that was registered.
To get the representation for a named tag:
struct fscache_cache_tag *fscache_lookup_cache_tag(const char *name);
This takes a text string as the name and returns a representation of a tag. It
will never return an error. It may return a dummy tag, however, if it runs out
of memory; this will inhibit caching with this tag.
Any representation so obtained must be released by passing it to this function:
void fscache_release_cache_tag(struct fscache_cache_tag *tag);
The tag will be retrieved by FS-Cache when it calls the object definition
operation select_cache().
==================
INDEX REGISTRATION
==================
The third step is to inform FS-Cache about part of an index hierarchy that can
be used to locate files. This is done by requesting a cookie for each index in
the path to the file:
struct fscache_cookie *
fscache_acquire_cookie(struct fscache_cookie *parent,
const struct fscache_object_def *def,
void *netfs_data);
This function creates an index entry in the index represented by parent,
filling in the index entry by calling the operations pointed to by def.
Note that this function never returns an error - all errors are handled
internally. It may, however, return NULL to indicate no cookie. It is quite
acceptable to pass this token back to this function as the parent to another
acquisition (or even to the relinquish cookie, read page and write page
functions - see below).
Note also that no indices are actually created in a cache until a non-index
object needs to be created somewhere down the hierarchy. Furthermore, an index
may be created in several different caches independently at different times.
This is all handled transparently, and the netfs doesn't see any of it.
For example, with AFS, a cell would be added to the primary index. This index
entry would have a dependent inode containing a volume location index for the
volume mappings within this cell:
cell->cache =
fscache_acquire_cookie(afs_cache_netfs.primary_index,
&afs_cell_cache_index_def,
cell);
Then when a volume location was accessed, it would be entered into the cell's
index and an inode would be allocated that acts as a volume type and hash chain
combination:
vlocation->cache =
fscache_acquire_cookie(cell->cache,
&afs_vlocation_cache_index_def,
vlocation);
And then a particular flavour of volume (R/O for example) could be added to
that index, creating another index for vnodes (AFS inode equivalents):
volume->cache =
fscache_acquire_cookie(vlocation->cache,
&afs_volume_cache_index_def,
volume);
======================
DATA FILE REGISTRATION
======================
The fourth step is to request a data file be created in the cache. This is
identical to index cookie acquisition. The only difference is that the type in
the object definition should be something other than index type.
vnode->cache =
fscache_acquire_cookie(volume->cache,
&afs_vnode_cache_object_def,
vnode);
=================================
MISCELLANEOUS OBJECT REGISTRATION
=================================
An optional step is to request an object of miscellaneous type be created in
the cache. This is almost identical to index cookie acquisition. The only
difference is that the type in the object definition should be something other
than index type. Whilst the parent object could be an index, it's more likely
it would be some other type of object such as a data file.
xattr->cache =
fscache_acquire_cookie(vnode->cache,
&afs_xattr_cache_object_def,
xattr);
Miscellaneous objects might be used to store extended attributes or directory
entries for example.
==========================
SETTING THE DATA FILE SIZE
==========================
The fifth step is to set the physical attributes of the file, such as its size.
This doesn't automatically reserve any space in the cache, but permits the
cache to adjust its metadata for data tracking appropriately:
int fscache_attr_changed(struct fscache_cookie *cookie);
The cache will return -ENOBUFS if there is no backing cache or if there is no
space to allocate any extra metadata required in the cache. The attributes
will be accessed with the get_attr() cookie definition operation.
Note that attempts to read or write data pages in the cache over this size may
be rebuffed with -ENOBUFS.
This operation schedules an attribute adjustment to happen asynchronously at
some point in the future, and as such, it may happen after the function returns
to the caller. The attribute adjustment excludes read and write operations.
=====================
PAGE READ/ALLOC/WRITE
=====================
And the sixth step is to store and retrieve pages in the cache. There are
three functions that are used to do this.
Note:
(1) A page should not be re-read or re-allocated without uncaching it first.
(2) A read or allocated page must be uncached when the netfs page is released
from the pagecache.
(3) A page should only be written to the cache if previous read or allocated.
This permits the cache to maintain its page tracking in proper order.
PAGE READ
---------
Firstly, the netfs should ask FS-Cache to examine the caches and read the
contents cached for a particular page of a particular file if present, or else
allocate space to store the contents if not:
typedef
void (*fscache_rw_complete_t)(struct page *page,
void *context,
int error);
int fscache_read_or_alloc_page(struct fscache_cookie *cookie,
struct page *page,
fscache_rw_complete_t end_io_func,
void *context,
gfp_t gfp);
The cookie argument must specify a cookie for an object that isn't an index,
the page specified will have the data loaded into it (and is also used to
specify the page number), and the gfp argument is used to control how any
memory allocations made are satisfied.
If the cookie indicates the inode is not cached:
(1) The function will return -ENOBUFS.
Else if there's a copy of the page resident in the cache:
(1) The mark_pages_cached() cookie operation will be called on that page.
(2) The function will submit a request to read the data from the cache's
backing device directly into the page specified.
(3) The function will return 0.
(4) When the read is complete, end_io_func() will be invoked with:
(*) The netfs data supplied when the cookie was created.
(*) The page descriptor.
(*) The context argument passed to the above function. This will be
maintained with the get_context/put_context functions mentioned above.
(*) An argument that's 0 on success or negative for an error code.
If an error occurs, it should be assumed that the page contains no usable
data.
end_io_func() will be called in process context if the read is results in
an error, but it might be called in interrupt context if the read is
successful.
Otherwise, if there's not a copy available in cache, but the cache may be able
to store the page:
(1) The mark_pages_cached() cookie operation will be called on that page.
(2) A block may be reserved in the cache and attached to the object at the
appropriate place.
(3) The function will return -ENODATA.
This function may also return -ENOMEM or -EINTR, in which case it won't have
read any data from the cache.
PAGE ALLOCATE
-------------
Alternatively, if there's not expected to be any data in the cache for a page
because the file has been extended, a block can simply be allocated instead:
int fscache_alloc_page(struct fscache_cookie *cookie,
struct page *page,
gfp_t gfp);
This is similar to the fscache_read_or_alloc_page() function, except that it
never reads from the cache. It will return 0 if a block has been allocated,
rather than -ENODATA as the other would. One or the other must be performed
before writing to the cache.
The mark_pages_cached() cookie operation will be called on the page if
successful.
PAGE WRITE
----------
Secondly, if the netfs changes the contents of the page (either due to an
initial download or if a user performs a write), then the page should be
written back to the cache:
int fscache_write_page(struct fscache_cookie *cookie,
struct page *page,
gfp_t gfp);
The cookie argument must specify a data file cookie, the page specified should
contain the data to be written (and is also used to specify the page number),
and the gfp argument is used to control how any memory allocations made are
satisfied.
The page must have first been read or allocated successfully and must not have
been uncached before writing is performed.
If the cookie indicates the inode is not cached then:
(1) The function will return -ENOBUFS.
Else if space can be allocated in the cache to hold this page:
(1) PG_fscache_write will be set on the page.
(2) The function will submit a request to write the data to cache's backing
device directly from the page specified.
(3) The function will return 0.
(4) When the write is complete PG_fscache_write is cleared on the page and
anyone waiting for that bit will be woken up.
Else if there's no space available in the cache, -ENOBUFS will be returned. It
is also possible for the PG_fscache_write bit to be cleared when no write took
place if unforeseen circumstances arose (such as a disk error).
Writing takes place asynchronously.
MULTIPLE PAGE READ
------------------
A facility is provided to read several pages at once, as requested by the
readpages() address space operation:
int fscache_read_or_alloc_pages(struct fscache_cookie *cookie,
struct address_space *mapping,
struct list_head *pages,
int *nr_pages,
fscache_rw_complete_t end_io_func,
void *context,
gfp_t gfp);
This works in a similar way to fscache_read_or_alloc_page(), except:
(1) Any page it can retrieve data for is removed from pages and nr_pages and
dispatched for reading to the disk. Reads of adjacent pages on disk may
be merged for greater efficiency.
(2) The mark_pages_cached() cookie operation will be called on several pages
at once if they're being read or allocated.
(3) If there was an general error, then that error will be returned.
Else if some pages couldn't be allocated or read, then -ENOBUFS will be
returned.
Else if some pages couldn't be read but were allocated, then -ENODATA will
be returned.
Otherwise, if all pages had reads dispatched, then 0 will be returned, the
list will be empty and *nr_pages will be 0.
(4) end_io_func will be called once for each page being read as the reads
complete. It will be called in process context if error != 0, but it may
be called in interrupt context if there is no error.
Note that a return of -ENODATA, -ENOBUFS or any other error does not preclude
some of the pages being read and some being allocated. Those pages will have
been marked appropriately and will need uncaching.
==============
PAGE UNCACHING
==============
To uncache a page, this function should be called:
void fscache_uncache_page(struct fscache_cookie *cookie,
struct page *page);
This function permits the cache to release any in-memory representation it
might be holding for this netfs page. This function must be called once for
each page on which the read or write page functions above have been called to
make sure the cache's in-memory tracking information gets torn down.
Note that pages can't be explicitly deleted from the a data file. The whole
data file must be retired (see the relinquish cookie function below).
Furthermore, note that this does not cancel the asynchronous read or write
operation started by the read/alloc and write functions, so the page
invalidation and release functions must use:
bool fscache_check_page_write(struct fscache_cookie *cookie,
struct page *page);
to see if a page is being written to the cache, and:
void fscache_wait_on_page_write(struct fscache_cookie *cookie,
struct page *page);
to wait for it to finish if it is.
==========================
INDEX AND DATA FILE UPDATE
==========================
To request an update of the index data for an index or other object, the
following function should be called:
void fscache_update_cookie(struct fscache_cookie *cookie);
This function will refer back to the netfs_data pointer stored in the cookie by
the acquisition function to obtain the data to write into each revised index
entry. The update method in the parent index definition will be called to
transfer the data.
Note that partial updates may happen automatically at other times, such as when
data blocks are added to a data file object.
===============================
MISCELLANEOUS COOKIE OPERATIONS
===============================
There are a number of operations that can be used to control cookies:
(*) Cookie pinning:
int fscache_pin_cookie(struct fscache_cookie *cookie);
void fscache_unpin_cookie(struct fscache_cookie *cookie);
These operations permit data cookies to be pinned into the cache and to
have the pinning removed. They are not permitted on index cookies.
The pinning function will return 0 if successful, -ENOBUFS in the cookie
isn't backed by a cache, -EOPNOTSUPP if the cache doesn't support pinning,
-ENOSPC if there isn't enough space to honour the operation, -ENOMEM or
-EIO if there's any other problem.
(*) Data space reservation:
int fscache_reserve_space(struct fscache_cookie *cookie, loff_t size);
This permits a netfs to request cache space be reserved to store up to the
given amount of a file. It is permitted to ask for more than the current
size of the file to allow for future file expansion.
If size is given as zero then the reservation will be cancelled.
The function will return 0 if successful, -ENOBUFS in the cookie isn't
backed by a cache, -EOPNOTSUPP if the cache doesn't support reservations,
-ENOSPC if there isn't enough space to honour the operation, -ENOMEM or
-EIO if there's any other problem.
Note that this doesn't pin an object in a cache; it can still be culled to
make space if it's not in use.
=====================
COOKIE UNREGISTRATION
=====================
To get rid of a cookie, this function should be called.
void fscache_relinquish_cookie(struct fscache_cookie *cookie,
int retire);
If retire is non-zero, then the object will be marked for recycling, and all
copies of it will be removed from all active caches in which it is present.
Not only that but all child objects will also be retired.
If retire is zero, then the object may be available again when next the
acquisition function is called. Retirement here will overrule the pinning on a
cookie.
One very important note - relinquish must NOT be called for a cookie unless all
the cookies for "child" indices, objects and pages have been relinquished
first.
================================
INDEX AND DATA FILE INVALIDATION
================================
There is no direct way to invalidate an index subtree or a data file. To do
this, the caller should relinquish and retire the cookie they have, and then
acquire a new one.
===========================
FS-CACHE SPECIFIC PAGE FLAG
===========================
FS-Cache makes use of a page flag, PG_private_2, for its own purpose. This is
given the alternative name PG_fscache.
PG_fscache is used to indicate that the page is known by the cache, and that
the cache must be informed if the page is going to go away. It's an indication
to the netfs that the cache has an interest in this page, where an interest may
be a pointer to it, resources allocated or reserved for it, or I/O in progress
upon it.
The netfs can use this information in methods such as releasepage() to
determine whether it needs to uncache a page or update it.
Furthermore, if this bit is set, releasepage() and invalidatepage() operations
will be called on a page to get rid of it, even if PG_private is not set. This
allows caching to attempted on a page before read_cache_pages() to be called
after fscache_read_or_alloc_pages() as the former will try and release pages it
was given under certain circumstances.
This bit does not overlap with such as PG_private. This means that FS-Cache
can be used with a filesystem that uses the block buffering code.
There are a number of operations defined on this flag:
int PageFsCache(struct page *page);
void SetPageFsCache(struct page *page)
void ClearPageFsCache(struct page *page)
int TestSetPageFsCache(struct page *page)
int TestClearPageFsCache(struct page *page)
These functions are bit test, bit set, bit clear, bit test and set and bit
test and clear operations on PG_fscache.

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====================================================
IN-KERNEL CACHE OBJECT REPRESENTATION AND MANAGEMENT
====================================================
By: David Howells <dhowells@redhat.com>
Contents:
(*) Representation
(*) Object management state machine.
- Provision of cpu time.
- Locking simplification.
(*) The set of states.
(*) The set of events.
==============
REPRESENTATION
==============
FS-Cache maintains an in-kernel representation of each object that a netfs is
currently interested in. Such objects are represented by the fscache_cookie
struct and are referred to as cookies.
FS-Cache also maintains a separate in-kernel representation of the objects that
a cache backend is currently actively caching. Such objects are represented by
the fscache_object struct. The cache backends allocate these upon request, and
are expected to embed them in their own representations. These are referred to
as objects.
There is a 1:N relationship between cookies and objects. A cookie may be
represented by multiple objects - an index may exist in more than one cache -
or even by no objects (it may not be cached).
Furthermore, both cookies and objects are hierarchical. The two hierarchies
correspond, but the cookies tree is a superset of the union of the object trees
of multiple caches:
NETFS INDEX TREE : CACHE 1 : CACHE 2
: :
: +-----------+ :
+----------->| IObject | :
+-----------+ | : +-----------+ :
| ICookie |-------+ : | :
+-----------+ | : | : +-----------+
| +------------------------------>| IObject |
| : | : +-----------+
| : V : |
| : +-----------+ : |
V +----------->| IObject | : |
+-----------+ | : +-----------+ : |
| ICookie |-------+ : | : V
+-----------+ | : | : +-----------+
| +------------------------------>| IObject |
+-----+-----+ : | : +-----------+
| | : | : |
V | : V : |
+-----------+ | : +-----------+ : |
| ICookie |------------------------->| IObject | : |
+-----------+ | : +-----------+ : |
| V : | : V
| +-----------+ : | : +-----------+
| | ICookie |-------------------------------->| IObject |
| +-----------+ : | : +-----------+
V | : V : |
+-----------+ | : +-----------+ : |
| DCookie |------------------------->| DObject | : |
+-----------+ | : +-----------+ : |
| : : |
+-------+-------+ : : |
| | : : |
V V : : V
+-----------+ +-----------+ : : +-----------+
| DCookie | | DCookie |------------------------>| DObject |
+-----------+ +-----------+ : : +-----------+
: :
In the above illustration, ICookie and IObject represent indices and DCookie
and DObject represent data storage objects. Indices may have representation in
multiple caches, but currently, non-index objects may not. Objects of any type
may also be entirely unrepresented.
As far as the netfs API goes, the netfs is only actually permitted to see
pointers to the cookies. The cookies themselves and any objects attached to
those cookies are hidden from it.
===============================
OBJECT MANAGEMENT STATE MACHINE
===============================
Within FS-Cache, each active object is managed by its own individual state
machine. The state for an object is kept in the fscache_object struct, in
object->state. A cookie may point to a set of objects that are in different
states.
Each state has an action associated with it that is invoked when the machine
wakes up in that state. There are four logical sets of states:
(1) Preparation: states that wait for the parent objects to become ready. The
representations are hierarchical, and it is expected that an object must
be created or accessed with respect to its parent object.
(2) Initialisation: states that perform lookups in the cache and validate
what's found and that create on disk any missing metadata.
(3) Normal running: states that allow netfs operations on objects to proceed
and that update the state of objects.
(4) Termination: states that detach objects from their netfs cookies, that
delete objects from disk, that handle disk and system errors and that free
up in-memory resources.
In most cases, transitioning between states is in response to signalled events.
When a state has finished processing, it will usually set the mask of events in
which it is interested (object->event_mask) and relinquish the worker thread.
Then when an event is raised (by calling fscache_raise_event()), if the event
is not masked, the object will be queued for processing (by calling
fscache_enqueue_object()).
PROVISION OF CPU TIME
---------------------
The work to be done by the various states is given CPU time by the threads of
the slow work facility (see Documentation/slow-work.txt). This is used in
preference to the workqueue facility because:
(1) Threads may be completely occupied for very long periods of time by a
particular work item. These state actions may be doing sequences of
synchronous, journalled disk accesses (lookup, mkdir, create, setxattr,
getxattr, truncate, unlink, rmdir, rename).
(2) Threads may do little actual work, but may rather spend a lot of time
sleeping on I/O. This means that single-threaded and 1-per-CPU-threaded
workqueues don't necessarily have the right numbers of threads.
LOCKING SIMPLIFICATION
----------------------
Because only one worker thread may be operating on any particular object's
state machine at once, this simplifies the locking, particularly with respect
to disconnecting the netfs's representation of a cache object (fscache_cookie)
from the cache backend's representation (fscache_object) - which may be
requested from either end.
=================
THE SET OF STATES
=================
The object state machine has a set of states that it can be in. There are
preparation states in which the object sets itself up and waits for its parent
object to transit to a state that allows access to its children:
(1) State FSCACHE_OBJECT_INIT.
Initialise the object and wait for the parent object to become active. In
the cache, it is expected that it will not be possible to look an object
up from the parent object, until that parent object itself has been looked
up.
There are initialisation states in which the object sets itself up and accesses
disk for the object metadata:
(2) State FSCACHE_OBJECT_LOOKING_UP.
Look up the object on disk, using the parent as a starting point.
FS-Cache expects the cache backend to probe the cache to see whether this
object is represented there, and if it is, to see if it's valid (coherency
management).
The cache should call fscache_object_lookup_negative() to indicate lookup
failure for whatever reason, and should call fscache_obtained_object() to
indicate success.
At the completion of lookup, FS-Cache will let the netfs go ahead with
read operations, no matter whether the file is yet cached. If not yet
cached, read operations will be immediately rejected with ENODATA until
the first known page is uncached - as to that point there can be no data
to be read out of the cache for that file that isn't currently also held
in the pagecache.
(3) State FSCACHE_OBJECT_CREATING.
Create an object on disk, using the parent as a starting point. This
happens if the lookup failed to find the object, or if the object's
coherency data indicated what's on disk is out of date. In this state,
FS-Cache expects the cache to create
The cache should call fscache_obtained_object() if creation completes
successfully, fscache_object_lookup_negative() otherwise.
At the completion of creation, FS-Cache will start processing write
operations the netfs has queued for an object. If creation failed, the
write ops will be transparently discarded, and nothing recorded in the
cache.
There are some normal running states in which the object spends its time
servicing netfs requests:
(4) State FSCACHE_OBJECT_AVAILABLE.
A transient state in which pending operations are started, child objects
are permitted to advance from FSCACHE_OBJECT_INIT state, and temporary
lookup data is freed.
(5) State FSCACHE_OBJECT_ACTIVE.
The normal running state. In this state, requests the netfs makes will be
passed on to the cache.
(6) State FSCACHE_OBJECT_UPDATING.
The state machine comes here to update the object in the cache from the
netfs's records. This involves updating the auxiliary data that is used
to maintain coherency.
And there are terminal states in which an object cleans itself up, deallocates
memory and potentially deletes stuff from disk:
(7) State FSCACHE_OBJECT_LC_DYING.
The object comes here if it is dying because of a lookup or creation
error. This would be due to a disk error or system error of some sort.
Temporary data is cleaned up, and the parent is released.
(8) State FSCACHE_OBJECT_DYING.
The object comes here if it is dying due to an error, because its parent
cookie has been relinquished by the netfs or because the cache is being
withdrawn.
Any child objects waiting on this one are given CPU time so that they too
can destroy themselves. This object waits for all its children to go away
before advancing to the next state.
(9) State FSCACHE_OBJECT_ABORT_INIT.
The object comes to this state if it was waiting on its parent in
FSCACHE_OBJECT_INIT, but its parent died. The object will destroy itself
so that the parent may proceed from the FSCACHE_OBJECT_DYING state.
(10) State FSCACHE_OBJECT_RELEASING.
(11) State FSCACHE_OBJECT_RECYCLING.
The object comes to one of these two states when dying once it is rid of
all its children, if it is dying because the netfs relinquished its
cookie. In the first state, the cached data is expected to persist, and
in the second it will be deleted.
(12) State FSCACHE_OBJECT_WITHDRAWING.
The object transits to this state if the cache decides it wants to
withdraw the object from service, perhaps to make space, but also due to
error or just because the whole cache is being withdrawn.
(13) State FSCACHE_OBJECT_DEAD.
The object transits to this state when the in-memory object record is
ready to be deleted. The object processor shouldn't ever see an object in
this state.
THE SET OF EVENTS
-----------------
There are a number of events that can be raised to an object state machine:
(*) FSCACHE_OBJECT_EV_UPDATE
The netfs requested that an object be updated. The state machine will ask
the cache backend to update the object, and the cache backend will ask the
netfs for details of the change through its cookie definition ops.
(*) FSCACHE_OBJECT_EV_CLEARED
This is signalled in two circumstances:
(a) when an object's last child object is dropped and
(b) when the last operation outstanding on an object is completed.
This is used to proceed from the dying state.
(*) FSCACHE_OBJECT_EV_ERROR
This is signalled when an I/O error occurs during the processing of some
object.
(*) FSCACHE_OBJECT_EV_RELEASE
(*) FSCACHE_OBJECT_EV_RETIRE
These are signalled when the netfs relinquishes a cookie it was using.
The event selected depends on whether the netfs asks for the backing
object to be retired (deleted) or retained.
(*) FSCACHE_OBJECT_EV_WITHDRAW
This is signalled when the cache backend wants to withdraw an object.
This means that the object will have to be detached from the netfs's
cookie.
Because the withdrawing releasing/retiring events are all handled by the object
state machine, it doesn't matter if there's a collision with both ends trying
to sever the connection at the same time. The state machine can just pick
which one it wants to honour, and that effects the other.

213
Documentation/filesystems/caching/operations.txt Normal file
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@ -0,0 +1,213 @@
================================
ASYNCHRONOUS OPERATIONS HANDLING
================================
By: David Howells <dhowells@redhat.com>
Contents:
(*) Overview.
(*) Operation record initialisation.
(*) Parameters.
(*) Procedure.
(*) Asynchronous callback.
========
OVERVIEW
========
FS-Cache has an asynchronous operations handling facility that it uses for its
data storage and retrieval routines. Its operations are represented by
fscache_operation structs, though these are usually embedded into some other
structure.
This facility is available to and expected to be be used by the cache backends,
and FS-Cache will create operations and pass them off to the appropriate cache
backend for completion.
To make use of this facility, <linux/fscache-cache.h> should be #included.
===============================
OPERATION RECORD INITIALISATION
===============================
An operation is recorded in an fscache_operation struct:
struct fscache_operation {
union {
struct work_struct fast_work;
struct slow_work slow_work;
};
unsigned long flags;
fscache_operation_processor_t processor;
...
};
Someone wanting to issue an operation should allocate something with this
struct embedded in it. They should initialise it by calling:
void fscache_operation_init(struct fscache_operation *op,
fscache_operation_release_t release);
with the operation to be initialised and the release function to use.
The op->flags parameter should be set to indicate the CPU time provision and
the exclusivity (see the Parameters section).
The op->fast_work, op->slow_work and op->processor flags should be set as
appropriate for the CPU time provision (see the Parameters section).
FSCACHE_OP_WAITING may be set in op->flags prior to each submission of the
operation and waited for afterwards.
==========
PARAMETERS
==========
There are a number of parameters that can be set in the operation record's flag
parameter. There are three options for the provision of CPU time in these
operations:
(1) The operation may be done synchronously (FSCACHE_OP_MYTHREAD). A thread
may decide it wants to handle an operation itself without deferring it to
another thread.
This is, for example, used in read operations for calling readpages() on
the backing filesystem in CacheFiles. Although readpages() does an
asynchronous data fetch, the determination of whether pages exist is done
synchronously - and the netfs does not proceed until this has been
determined.
If this option is to be used, FSCACHE_OP_WAITING must be set in op->flags
before submitting the operation, and the operating thread must wait for it
to be cleared before proceeding:
wait_on_bit(&op->flags, FSCACHE_OP_WAITING,
fscache_wait_bit, TASK_UNINTERRUPTIBLE);
(2) The operation may be fast asynchronous (FSCACHE_OP_FAST), in which case it
will be given to keventd to process. Such an operation is not permitted
to sleep on I/O.
This is, for example, used by CacheFiles to copy data from a backing fs
page to a netfs page after the backing fs has read the page in.
If this option is used, op->fast_work and op->processor must be
initialised before submitting the operation:
INIT_WORK(&op->fast_work, do_some_work);
(3) The operation may be slow asynchronous (FSCACHE_OP_SLOW), in which case it
will be given to the slow work facility to process. Such an operation is
permitted to sleep on I/O.
This is, for example, used by FS-Cache to handle background writes of
pages that have just been fetched from a remote server.
If this option is used, op->slow_work and op->processor must be
initialised before submitting the operation:
fscache_operation_init_slow(op, processor)
Furthermore, operations may be one of two types:
(1) Exclusive (FSCACHE_OP_EXCLUSIVE). Operations of this type may not run in
conjunction with any other operation on the object being operated upon.
An example of this is the attribute change operation, in which the file
being written to may need truncation.
(2) Shareable. Operations of this type may be running simultaneously. It's
up to the operation implementation to prevent interference between other
operations running at the same time.
=========
PROCEDURE
=========
Operations are used through the following procedure:
(1) The submitting thread must allocate the operation and initialise it
itself. Normally this would be part of a more specific structure with the
generic op embedded within.
(2) The submitting thread must then submit the operation for processing using
one of the following two functions:
int fscache_submit_op(struct fscache_object *object,
struct fscache_operation *op);
int fscache_submit_exclusive_op(struct fscache_object *object,
struct fscache_operation *op);
The first function should be used to submit non-exclusive ops and the
second to submit exclusive ones. The caller must still set the
FSCACHE_OP_EXCLUSIVE flag.
If successful, both functions will assign the operation to the specified
object and return 0. -ENOBUFS will be returned if the object specified is
permanently unavailable.
The operation manager will defer operations on an object that is still
undergoing lookup or creation. The operation will also be deferred if an
operation of conflicting exclusivity is in progress on the object.
If the operation is asynchronous, the manager will retain a reference to
it, so the caller should put their reference to it by passing it to:
void fscache_put_operation(struct fscache_operation *op);
(3) If the submitting thread wants to do the work itself, and has marked the
operation with FSCACHE_OP_MYTHREAD, then it should monitor
FSCACHE_OP_WAITING as described above and check the state of the object if
necessary (the object might have died whilst the thread was waiting).
When it has finished doing its processing, it should call
fscache_put_operation() on it.
(4) The operation holds an effective lock upon the object, preventing other
exclusive ops conflicting until it is released. The operation can be
enqueued for further immediate asynchronous processing by adjusting the
CPU time provisioning option if necessary, eg:
op->flags &= ~FSCACHE_OP_TYPE;
op->flags |= ~FSCACHE_OP_FAST;
and calling:
void fscache_enqueue_operation(struct fscache_operation *op)
This can be used to allow other things to have use of the worker thread
pools.
=====================
ASYNCHRONOUS CALLBACK
=====================
When used in asynchronous mode, the worker thread pool will invoke the
processor method with a pointer to the operation. This should then get at the
container struct by using container_of():
static void fscache_write_op(struct fscache_operation *_op)
{
struct fscache_storage *op =
container_of(_op, struct fscache_storage, op);
...
}
The caller holds a reference on the operation, and will invoke
fscache_put_operation() when the processor function returns. The processor
function is at liberty to call fscache_enqueue_operation() or to take extra
references.

174
Documentation/slow-work.txt Normal file
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@ -0,0 +1,174 @@
====================================
SLOW WORK ITEM EXECUTION THREAD POOL
====================================
By: David Howells <dhowells@redhat.com>
The slow work item execution thread pool is a pool of threads for performing
things that take a relatively long time, such as making mkdir calls.
Typically, when processing something, these items will spend a lot of time
blocking a thread on I/O, thus making that thread unavailable for doing other
work.
The standard workqueue model is unsuitable for this class of work item as that
limits the owner to a single thread or a single thread per CPU. For some
tasks, however, more threads - or fewer - are required.
There is just one pool per system. It contains no threads unless something
wants to use it - and that something must register its interest first. When
the pool is active, the number of threads it contains is dynamic, varying
between a maximum and minimum setting, depending on the load.
====================
CLASSES OF WORK ITEM
====================
This pool support two classes of work items:
(*) Slow work items.
(*) Very slow work items.
The former are expected to finish much quicker than the latter.
An operation of the very slow class may do a batch combination of several
lookups, mkdirs, and a create for instance.
An operation of the ordinarily slow class may, for example, write stuff or
expand files, provided the time taken to do so isn't too long.
Operations of both types may sleep during execution, thus tying up the thread
loaned to it.
THREAD-TO-CLASS ALLOCATION
--------------------------
Not all the threads in the pool are available to work on very slow work items.
The number will be between one and one fewer than the number of active threads.
This is configurable (see the "Pool Configuration" section).
All the threads are available to work on ordinarily slow work items, but a
percentage of the threads will prefer to work on very slow work items.
The configuration ensures that at least one thread will be available to work on
very slow work items, and at least one thread will be available that won't work
on very slow work items at all.
=====================
USING SLOW WORK ITEMS
=====================
Firstly, a module or subsystem wanting to make use of slow work items must
register its interest:
int ret = slow_work_register_user();
This will return 0 if successful, or a -ve error upon failure.
Slow work items may then be set up by:
(1) Declaring a slow_work struct type variable:
#include <linux/slow-work.h>
struct slow_work myitem;
(2) Declaring the operations to be used for this item:
struct slow_work_ops myitem_ops = {
.get_ref = myitem_get_ref,
.put_ref = myitem_put_ref,
.execute = myitem_execute,
};
[*] For a description of the ops, see section "Item Operations".
(3) Initialising the item:
slow_work_init(&myitem, &myitem_ops);
or:
vslow_work_init(&myitem, &myitem_ops);
depending on its class.
A suitably set up work item can then be enqueued for processing:
int ret = slow_work_enqueue(&myitem);
This will return a -ve error if the thread pool is unable to gain a reference
on the item, 0 otherwise.
The items are reference counted, so there ought to be no need for a flush
operation. When all a module's slow work items have been processed, and the
module has no further interest in the facility, it should unregister its
interest:
slow_work_unregister_user();
===============
ITEM OPERATIONS
===============
Each work item requires a table of operations of type struct slow_work_ops.
All members are required:
(*) Get a reference on an item:
int (*get_ref)(struct slow_work *work);
This allows the thread pool to attempt to pin an item by getting a
reference on it. This function should return 0 if the reference was
granted, or a -ve error otherwise. If an error is returned,
slow_work_enqueue() will fail.
The reference is held whilst the item is queued and whilst it is being
executed. The item may then be requeued with the same reference held, or
the reference will be released.
(*) Release a reference on an item:
void (*put_ref)(struct slow_work *work);
This allows the thread pool to unpin an item by releasing the reference on
it. The thread pool will not touch the item again once this has been
called.
(*) Execute an item:
void (*execute)(struct slow_work *work);
This should perform the work required of the item. It may sleep, it may
perform disk I/O and it may wait for locks.
==================
POOL CONFIGURATION
==================
The slow-work thread pool has a number of configurables:
(*) /proc/sys/kernel/slow-work/min-threads
The minimum number of threads that should be in the pool whilst it is in
use. This may be anywhere between 2 and max-threads.
(*) /proc/sys/kernel/slow-work/max-threads
The maximum number of threads that should in the pool. This may be
anywhere between min-threads and 255 or NR_CPUS * 2, whichever is greater.
(*) /proc/sys/kernel/slow-work/vslow-percentage
The percentage of active threads in the pool that may be used to execute
very slow work items. This may be between 1 and 99. The resultant number
is bounded to between 1 and one fewer than the number of active threads.
This ensures there is always at least one thread that can process very
slow work items, and always at least one thread that won't.

7
fs/Kconfig
View File

@ -66,6 +66,13 @@ config GENERIC_ACL
bool
select FS_POSIX_ACL
menu "Caches"
source "fs/fscache/Kconfig"
source "fs/cachefiles/Kconfig"
endmenu
if BLOCK
menu "CD-ROM/DVD Filesystems"

2
fs/Makefile
View File

@ -63,6 +63,7 @@ obj-$(CONFIG_PROFILING) += dcookies.o
obj-$(CONFIG_DLM) += dlm/
# Do not add any filesystems before this line
obj-$(CONFIG_FSCACHE) += fscache/
obj-$(CONFIG_REISERFS_FS) += reiserfs/
obj-$(CONFIG_EXT3_FS) += ext3/ # Before ext2 so root fs can be ext3
obj-$(CONFIG_EXT2_FS) += ext2/
@ -116,6 +117,7 @@ obj-$(CONFIG_AFS_FS) += afs/
obj-$(CONFIG_BEFS_FS) += befs/
obj-$(CONFIG_HOSTFS) += hostfs/
obj-$(CONFIG_HPPFS) += hppfs/
obj-$(CONFIG_CACHEFILES) += cachefiles/
obj-$(CONFIG_DEBUG_FS) += debugfs/
obj-$(CONFIG_OCFS2_FS) += ocfs2/
obj-$(CONFIG_BTRFS_FS) += btrfs/

8
fs/afs/Kconfig
View File

@ -19,3 +19,11 @@ config AFS_DEBUG
See <file:Documentation/filesystems/afs.txt> for more information.
If unsure, say N.
config AFS_FSCACHE
bool "Provide AFS client caching support (EXPERIMENTAL)"
depends on EXPERIMENTAL
depends on AFS_FS=m && FSCACHE || AFS_FS=y && FSCACHE=y
help
Say Y here if you want AFS data to be cached locally on disk through
the generic filesystem cache manager

3
fs/afs/Makefile
View File

@ -2,7 +2,10 @@
# Makefile for Red Hat Linux AFS client.
#
afs-cache-$(CONFIG_AFS_FSCACHE) := cache.o
kafs-objs := \
$(afs-cache-y) \
callback.o \
cell.o \
cmservice.o \

549
fs/afs/cache.c
View File

@ -1,6 +1,6 @@
/* AFS caching stuff
*
* Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
* Copyright (C) 2008 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
@ -9,248 +9,395 @@
* 2 of the License, or (at your option) any later version.
*/
#ifdef AFS_CACHING_SUPPORT
static cachefs_match_val_t afs_cell_cache_match(void *target,
const void *entry);
static void afs_cell_cache_update(void *source, void *entry);
#include <linux/slab.h>
#include <linux/sched.h>
#include "internal.h"
struct cachefs_index_def afs_cache_cell_index_def = {
.name = "cell_ix",
.data_size = sizeof(struct afs_cache_cell),
.keys[0] = { CACHEFS_INDEX_KEYS_ASCIIZ, 64 },
.match = afs_cell_cache_match,
.update = afs_cell_cache_update,
static uint16_t afs_cell_cache_get_key(const void *cookie_netfs_data,
void *buffer, uint16_t buflen);
static uint16_t afs_cell_cache_get_aux(const void *cookie_netfs_data,
void *buffer, uint16_t buflen);
static enum fscache_checkaux afs_cell_cache_check_aux(void *cookie_netfs_data,
const void *buffer,
uint16_t buflen);
static uint16_t afs_vlocation_cache_get_key(const void *cookie_netfs_data,
void *buffer, uint16_t buflen);
static uint16_t afs_vlocation_cache_get_aux(const void *cookie_netfs_data,
void *buffer, uint16_t buflen);
static enum fscache_checkaux afs_vlocation_cache_check_aux(
void *cookie_netfs_data, const void *buffer, uint16_t buflen);
static uint16_t afs_volume_cache_get_key(const void *cookie_netfs_data,
void *buffer, uint16_t buflen);
static uint16_t afs_vnode_cache_get_key(const void *cookie_netfs_data,
void *buffer, uint16_t buflen);
static void afs_vnode_cache_get_attr(const void *cookie_netfs_data,
uint64_t *size);
static uint16_t afs_vnode_cache_get_aux(const void *cookie_netfs_data,
void *buffer, uint16_t buflen);
static enum fscache_checkaux afs_vnode_cache_check_aux(void *cookie_netfs_data,
const void *buffer,
uint16_t buflen);
static void afs_vnode_cache_now_uncached(void *cookie_netfs_data);
struct fscache_netfs afs_cache_netfs = {
.name = "afs",
.version = 0,
};
struct fscache_cookie_def afs_cell_cache_index_def = {
.name = "AFS.cell",
.type = FSCACHE_COOKIE_TYPE_INDEX,
.get_key = afs_cell_cache_get_key,
.get_aux = afs_cell_cache_get_aux,
.check_aux = afs_cell_cache_check_aux,
};
struct fscache_cookie_def afs_vlocation_cache_index_def = {
.name = "AFS.vldb",
.type = FSCACHE_COOKIE_TYPE_INDEX,
.get_key = afs_vlocation_cache_get_key,
.get_aux = afs_vlocation_cache_get_aux,
.check_aux = afs_vlocation_cache_check_aux,
};
struct fscache_cookie_def afs_volume_cache_index_def = {
.name = "AFS.volume",
.type = FSCACHE_COOKIE_TYPE_INDEX,
.get_key = afs_volume_cache_get_key,
};
struct fscache_cookie_def afs_vnode_cache_index_def = {
.name = "AFS.vnode",
.type = FSCACHE_COOKIE_TYPE_DATAFILE,
.get_key = afs_vnode_cache_get_key,
.get_attr = afs_vnode_cache_get_attr,
.get_aux = afs_vnode_cache_get_aux,
.check_aux = afs_vnode_cache_check_aux,
.now_uncached = afs_vnode_cache_now_uncached,
};
#endif
/*
* match a cell record obtained from the cache
* set the key for the index entry
*/
#ifdef AFS_CACHING_SUPPORT
static cachefs_match_val_t afs_cell_cache_match(void *target,
const void *entry)
static uint16_t afs_cell_cache_get_key(const void *cookie_netfs_data,
void *buffer, uint16_t bufmax)
{
const struct afs_cache_cell *ccell = entry;
struct afs_cell *cell = target;
const struct afs_cell *cell = cookie_netfs_data;
uint16_t klen;
_enter("{%s},{%s}", ccell->name, cell->name);
_enter("%p,%p,%u", cell, buffer, bufmax);
if (strncmp(ccell->name, cell->name, sizeof(ccell->name)) == 0) {
_leave(" = SUCCESS");
return CACHEFS_MATCH_SUCCESS;
klen = strlen(cell->name);
if (klen > bufmax)
return 0;
memcpy(buffer, cell->name, klen);
return klen;
}
/*
* provide new auxilliary cache data
*/
static uint16_t afs_cell_cache_get_aux(const void *cookie_netfs_data,
void *buffer, uint16_t bufmax)
{
const struct afs_cell *cell = cookie_netfs_data;
uint16_t dlen;
_enter("%p,%p,%u", cell, buffer, bufmax);
dlen = cell->vl_naddrs * sizeof(cell->vl_addrs[0]);
dlen = min(dlen, bufmax);
dlen &= ~(sizeof(cell->vl_addrs[0]) - 1);
memcpy(buffer, cell->vl_addrs, dlen);
return dlen;
}
/*
* check that the auxilliary data indicates that the entry is still valid
*/
static enum fscache_checkaux afs_cell_cache_check_aux(void *cookie_netfs_data,
const void *buffer,
uint16_t buflen)
{
_leave(" = OKAY");
return FSCACHE_CHECKAUX_OKAY;
}
/*****************************************************************************/
/*
* set the key for the index entry
*/
static uint16_t afs_vlocation_cache_get_key(const void *cookie_netfs_data,
void *buffer, uint16_t bufmax)
{
const struct afs_vlocation *vlocation = cookie_netfs_data;
uint16_t klen;
_enter("{%s},%p,%u", vlocation->vldb.name, buffer, bufmax);
klen = strnlen(vlocation->vldb.name, sizeof(vlocation->vldb.name));
if (klen > bufmax)
return 0;
memcpy(buffer, vlocation->vldb.name, klen);
_leave(" = %u", klen);
return klen;
}
/*
* provide new auxilliary cache data
*/
static uint16_t afs_vlocation_cache_get_aux(const void *cookie_netfs_data,
void *buffer, uint16_t bufmax)
{
const struct afs_vlocation *vlocation = cookie_netfs_data;
uint16_t dlen;
_enter("{%s},%p,%u", vlocation->vldb.name, buffer, bufmax);
dlen = sizeof(struct afs_cache_vlocation);
dlen -= offsetof(struct afs_cache_vlocation, nservers);
if (dlen > bufmax)
return 0;
memcpy(buffer, (uint8_t *)&vlocation->vldb.nservers, dlen);
_leave(" = %u", dlen);
return dlen;
}
/*
* check that the auxilliary data indicates that the entry is still valid
*/
static
enum fscache_checkaux afs_vlocation_cache_check_aux(void *cookie_netfs_data,
const void *buffer,
uint16_t buflen)
{
const struct afs_cache_vlocation *cvldb;
struct afs_vlocation *vlocation = cookie_netfs_data;
uint16_t dlen;
_enter("{%s},%p,%u", vlocation->vldb.name, buffer, buflen);
/* check the size of the data is what we're expecting */
dlen = sizeof(struct afs_cache_vlocation);
dlen -= offsetof(struct afs_cache_vlocation, nservers);
if (dlen != buflen)
return FSCACHE_CHECKAUX_OBSOLETE;
cvldb = container_of(buffer, struct afs_cache_vlocation, nservers);
/* if what's on disk is more valid than what's in memory, then use the
* VL record from the cache */
if (!vlocation->valid || vlocation->vldb.rtime == cvldb->rtime) {
memcpy((uint8_t *)&vlocation->vldb.nservers, buffer, dlen);
vlocation->valid = 1;
_leave(" = SUCCESS [c->m]");
return FSCACHE_CHECKAUX_OKAY;
}
_leave(" = FAILED");
return CACHEFS_MATCH_FAILED;
}
#endif
/*
* update a cell record in the cache
*/
#ifdef AFS_CACHING_SUPPORT
static void afs_cell_cache_update(void *source, void *entry)
{
struct afs_cache_cell *ccell = entry;
struct afs_cell *cell = source;
_enter("%p,%p", source, entry);
strncpy(ccell->name, cell->name, sizeof(ccell->name));
memcpy(ccell->vl_servers,
cell->vl_addrs,
min(sizeof(ccell->vl_servers), sizeof(cell->vl_addrs)));
}
#endif
#ifdef AFS_CACHING_SUPPORT
static cachefs_match_val_t afs_vlocation_cache_match(void *target,
const void *entry);
static void afs_vlocation_cache_update(void *source, void *entry);
struct cachefs_index_def afs_vlocation_cache_index_def = {
.name = "vldb",
.data_size = sizeof(struct afs_cache_vlocation),
.keys[0] = { CACHEFS_INDEX_KEYS_ASCIIZ, 64 },
.match = afs_vlocation_cache_match,
.update = afs_vlocation_cache_update,
};
#endif
/*
* match a VLDB record stored in the cache
* - may also load target from entry
*/
#ifdef AFS_CACHING_SUPPORT
static cachefs_match_val_t afs_vlocation_cache_match(void *target,
const void *entry)
{
const struct afs_cache_vlocation *vldb = entry;
struct afs_vlocation *vlocation = target;
_enter("{%s},{%s}", vlocation->vldb.name, vldb->name);
if (strncmp(vlocation->vldb.name, vldb->name, sizeof(vldb->name)) == 0
) {
if (!vlocation->valid ||
vlocation->vldb.rtime == vldb->rtime
/* need to update the cache if the cached info differs */
if (memcmp(&vlocation->vldb, buffer, dlen) != 0) {
/* delete if the volume IDs for this name differ */
if (memcmp(&vlocation->vldb.vid, &cvldb->vid,
sizeof(cvldb->vid)) != 0
) {
vlocation->vldb = *vldb;
vlocation->valid = 1;
_leave(" = SUCCESS [c->m]");
return CACHEFS_MATCH_SUCCESS;
} else if (memcmp(&vlocation->vldb, vldb, sizeof(*vldb)) != 0) {
/* delete if VIDs for this name differ */
if (memcmp(&vlocation->vldb.vid,
&vldb->vid,
sizeof(vldb->vid)) != 0) {
_leave(" = DELETE");
return CACHEFS_MATCH_SUCCESS_DELETE;
}
_leave(" = UPDATE");
return CACHEFS_MATCH_SUCCESS_UPDATE;
} else {
_leave(" = SUCCESS");
return CACHEFS_MATCH_SUCCESS;
_leave(" = OBSOLETE");
return FSCACHE_CHECKAUX_OBSOLETE;
}
_leave(" = UPDATE");
return FSCACHE_CHECKAUX_NEEDS_UPDATE;
}
_leave(" = FAILED");
return CACHEFS_MATCH_FAILED;
_leave(" = OKAY");
return FSCACHE_CHECKAUX_OKAY;
}
/*****************************************************************************/
/*
* set the key for the volume index entry
*/
static uint16_t afs_volume_cache_get_key(const void *cookie_netfs_data,
void *buffer, uint16_t bufmax)
{
const struct afs_volume *volume = cookie_netfs_data;
uint16_t klen;
_enter("{%u},%p,%u", volume->type, buffer, bufmax);
klen = sizeof(volume->type);
if (klen > bufmax)
return 0;
memcpy(buffer, &volume->type, sizeof(volume->type));
_leave(" = %u", klen);
return klen;
}
/*****************************************************************************/
/*
* set the key for the index entry
*/
static uint16_t afs_vnode_cache_get_key(const void *cookie_netfs_data,
void *buffer, uint16_t bufmax)
{
const struct afs_vnode *vnode = cookie_netfs_data;
uint16_t klen;
_enter("{%x,%x,%llx},%p,%u",
vnode->fid.vnode, vnode->fid.unique, vnode->status.data_version,
buffer, bufmax);
klen = sizeof(vnode->fid.vnode);
if (klen > bufmax)
return 0;
memcpy(buffer, &vnode->fid.vnode, sizeof(vnode->fid.vnode));
_leave(" = %u", klen);
return klen;
}
#endif
/*
* update a VLDB record stored in the cache
* provide updated file attributes
*/
#ifdef AFS_CACHING_SUPPORT
static void afs_vlocation_cache_update(void *source, void *entry)
static void afs_vnode_cache_get_attr(const void *cookie_netfs_data,
uint64_t *size)
{
struct afs_cache_vlocation *vldb = entry;
struct afs_vlocation *vlocation = source;
const struct afs_vnode *vnode = cookie_netfs_data;
_enter("");
_enter("{%x,%x,%llx},",
vnode->fid.vnode, vnode->fid.unique,
vnode->status.data_version);
*vldb = vlocation->vldb;
*size = vnode->status.size;
}
#endif
#ifdef AFS_CACHING_SUPPORT
static cachefs_match_val_t afs_volume_cache_match(void *target,
const void *entry);
static void afs_volume_cache_update(void *source, void *entry);
struct cachefs_index_def afs_volume_cache_index_def = {
.name = "volume",
.data_size = sizeof(struct afs_cache_vhash),
.keys[0] = { CACHEFS_INDEX_KEYS_BIN, 1 },
.keys[1] = { CACHEFS_INDEX_KEYS_BIN, 1 },
.match = afs_volume_cache_match,
.update = afs_volume_cache_update,
};
#endif
/*
* match a volume hash record stored in the cache
* provide new auxilliary cache data
*/
#ifdef AFS_CACHING_SUPPORT
static cachefs_match_val_t afs_volume_cache_match(void *target,
const void *entry)
static uint16_t afs_vnode_cache_get_aux(const void *cookie_netfs_data,
void *buffer, uint16_t bufmax)
{
const struct afs_cache_vhash *vhash = entry;
struct afs_volume *volume = target;
const struct afs_vnode *vnode = cookie_netfs_data;
uint16_t dlen;
_enter("{%u},{%u}", volume->type, vhash->vtype);
_enter("{%x,%x,%Lx},%p,%u",
vnode->fid.vnode, vnode->fid.unique, vnode->status.data_version,
buffer, bufmax);
if (volume->type == vhash->vtype) {
_leave(" = SUCCESS");
return CACHEFS_MATCH_SUCCESS;
dlen = sizeof(vnode->fid.unique) + sizeof(vnode->status.data_version);
if (dlen > bufmax)
return 0;
memcpy(buffer, &vnode->fid.unique, sizeof(vnode->fid.unique));
buffer += sizeof(vnode->fid.unique);
memcpy(buffer, &vnode->status.data_version,
sizeof(vnode->status.data_version));
_leave(" = %u", dlen);
return dlen;
}
/*
* check that the auxilliary data indicates that the entry is still valid
*/
static enum fscache_checkaux afs_vnode_cache_check_aux(void *cookie_netfs_data,
const void *buffer,
uint16_t buflen)
{
struct afs_vnode *vnode = cookie_netfs_data;
uint16_t dlen;
_enter("{%x,%x,%llx},%p,%u",
vnode->fid.vnode, vnode->fid.unique, vnode->status.data_version,
buffer, buflen);
/* check the size of the data is what we're expecting */
dlen = sizeof(vnode->fid.unique) + sizeof(vnode->status.data_version);
if (dlen != buflen) {
_leave(" = OBSOLETE [len %hx != %hx]", dlen, buflen);
return FSCACHE_CHECKAUX_OBSOLETE;
}
_leave(" = FAILED");
return CACHEFS_MATCH_FAILED;
}
#endif
if (memcmp(buffer,
&vnode->fid.unique,
sizeof(vnode->fid.unique)
) != 0) {
unsigned unique;
/*
* update a volume hash record stored in the cache
*/
#ifdef AFS_CACHING_SUPPORT
static void afs_volume_cache_update(void *source, void *entry)
{
struct afs_cache_vhash *vhash = entry;
struct afs_volume *volume = source;
memcpy(&unique, buffer, sizeof(unique));
_enter("");
vhash->vtype = volume->type;
}
#endif
#ifdef AFS_CACHING_SUPPORT
static cachefs_match_val_t afs_vnode_cache_match(void *target,
const void *entry);
static void afs_vnode_cache_update(void *source, void *entry);
struct cachefs_index_def afs_vnode_cache_index_def = {
.name = "vnode",
.data_size = sizeof(struct afs_cache_vnode),
.keys[0] = { CACHEFS_INDEX_KEYS_BIN, 4 },
.match = afs_vnode_cache_match,
.update = afs_vnode_cache_update,
};
#endif
/*
* match a vnode record stored in the cache
*/
#ifdef AFS_CACHING_SUPPORT
static cachefs_match_val_t afs_vnode_cache_match(void *target,
const void *entry)
{
const struct afs_cache_vnode *cvnode = entry;
struct afs_vnode *vnode = target;
_enter("{%x,%x,%Lx},{%x,%x,%Lx}",
vnode->fid.vnode,
vnode->fid.unique,
vnode->status.version,
cvnode->vnode_id,
cvnode->vnode_unique,
cvnode->data_version);
if (vnode->fid.vnode != cvnode->vnode_id) {
_leave(" = FAILED");
return CACHEFS_MATCH_FAILED;
_leave(" = OBSOLETE [uniq %x != %x]",
unique, vnode->fid.unique);
return FSCACHE_CHECKAUX_OBSOLETE;
}
if (vnode->fid.unique != cvnode->vnode_unique ||
vnode->status.version != cvnode->data_version) {
_leave(" = DELETE");
return CACHEFS_MATCH_SUCCESS_DELETE;
if (memcmp(buffer + sizeof(vnode->fid.unique),
&vnode->status.data_version,
sizeof(vnode->status.data_version)
) != 0) {
afs_dataversion_t version;
memcpy(&version, buffer + sizeof(vnode->fid.unique),
sizeof(version));
_leave(" = OBSOLETE [vers %llx != %llx]",
version, vnode->status.data_version);
return FSCACHE_CHECKAUX_OBSOLETE;
}
_leave(" = SUCCESS");
return CACHEFS_MATCH_SUCCESS;
return FSCACHE_CHECKAUX_OKAY;
}
#endif
/*
* update a vnode record stored in the cache
* indication the cookie is no longer uncached
* - this function is called when the backing store currently caching a cookie
* is removed
* - the netfs should use this to clean up any markers indicating cached pages
* - this is mandatory for any object that may have data
*/
#ifdef AFS_CACHING_SUPPORT
static void afs_vnode_cache_update(void *source, void *entry)
static void afs_vnode_cache_now_uncached(void *cookie_netfs_data)
{
struct afs_cache_vnode *cvnode = entry;
struct afs_vnode *vnode = source;
struct afs_vnode *vnode = cookie_netfs_data;
struct pagevec pvec;
pgoff_t first;
int loop, nr_pages;
_enter("");
_enter("{%x,%x,%Lx}",
vnode->fid.vnode, vnode->fid.unique, vnode->status.data_version);
cvnode->vnode_id = vnode->fid.vnode;
cvnode->vnode_unique = vnode->fid.unique;
cvnode->data_version = vnode->status.version;
pagevec_init(&pvec, 0);
first = 0;
for (;;) {
/* grab a bunch of pages to clean */
nr_pages = pagevec_lookup(&pvec, vnode->vfs_inode.i_mapping,
first,
PAGEVEC_SIZE - pagevec_count(&pvec));
if (!nr_pages)
break;
for (loop = 0; loop < nr_pages; loop++)
ClearPageFsCache(pvec.pages[loop]);
first = pvec.pages[nr_pages - 1]->index + 1;
pvec.nr = nr_pages;
pagevec_release(&pvec);
cond_resched();
}
_leave("");
}
#endif

15
fs/afs/cache.h
View File

@ -1,6 +1,6 @@
/* AFS local cache management interface
*
* Copyright (C) 2002 Red Hat, Inc. All Rights Reserved.
* Copyright (C) 2008 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
@ -9,15 +9,4 @@
* 2 of the License, or (at your option) any later version.
*/
#ifndef AFS_CACHE_H
#define AFS_CACHE_H
#undef AFS_CACHING_SUPPORT
#include <linux/mm.h>
#ifdef AFS_CACHING_SUPPORT
#include <linux/cachefs.h>
#endif
#include "types.h"
#endif /* AFS_CACHE_H */
#include <linux/fscache.h>

16
fs/afs/cell.c
View File

@ -147,12 +147,11 @@ struct afs_cell *afs_cell_create(const char *name, char *vllist)
if (ret < 0)
goto error;
#ifdef AFS_CACHING_SUPPORT
/* put it up for caching */
cachefs_acquire_cookie(afs_cache_netfs.primary_index,
&afs_vlocation_cache_index_def,
cell,
&cell->cache);
#ifdef CONFIG_AFS_FSCACHE
/* put it up for caching (this never returns an error) */
cell->cache = fscache_acquire_cookie(afs_cache_netfs.primary_index,
&afs_cell_cache_index_def,
cell);
#endif
/* add to the cell lists */
@ -362,10 +361,9 @@ static void afs_cell_destroy(struct afs_cell *cell)
list_del_init(&cell->proc_link);
up_write(&afs_proc_cells_sem);
#ifdef AFS_CACHING_SUPPORT
cachefs_relinquish_cookie(cell->cache, 0);
#ifdef CONFIG_AFS_FSCACHE
fscache_relinquish_cookie(cell->cache, 0);
#endif
key_put(cell->anonymous_key);
kfree(cell);

222
fs/afs/file.c
View File

@ -23,6 +23,9 @@ static void afs_invalidatepage(struct page *page, unsigned long offset);
static int afs_releasepage(struct page *page, gfp_t gfp_flags);
static int afs_launder_page(struct page *page);
static int afs_readpages(struct file *filp, struct address_space *mapping,
struct list_head *pages, unsigned nr_pages);
const struct file_operations afs_file_operations = {
.open = afs_open,
.release = afs_release,
@ -46,6 +49,7 @@ const struct inode_operations afs_file_inode_operations = {
const struct address_space_operations afs_fs_aops = {
.readpage = afs_readpage,
.readpages = afs_readpages,
.set_page_dirty = afs_set_page_dirty,
.launder_page = afs_launder_page,
.releasepage = afs_releasepage,
@ -101,37 +105,18 @@ int afs_release(struct inode *inode, struct file *file)
/*
* deal with notification that a page was read from the cache
*/
#ifdef AFS_CACHING_SUPPORT
static void afs_readpage_read_complete(void *cookie_data,
struct page *page,
void *data,
int error)
static void afs_file_readpage_read_complete(struct page *page,
void *data,
int error)
{
_enter("%p,%p,%p,%d", cookie_data, page, data, error);
_enter("%p,%p,%d", page, data, error);
if (error)
SetPageError(page);
else
/* if the read completes with an error, we just unlock the page and let
* the VM reissue the readpage */
if (!error)
SetPageUptodate(page);
unlock_page(page);
}
#endif
/*
* deal with notification that a page was written to the cache
*/
#ifdef AFS_CACHING_SUPPORT
static void afs_readpage_write_complete(void *cookie_data,
struct page *page,
void *data,
int error)
{
_enter("%p,%p,%p,%d", cookie_data, page, data, error);
unlock_page(page);
}
#endif
/*
* AFS read page from file, directory or symlink
@ -161,9 +146,9 @@ static int afs_readpage(struct file *file, struct page *page)
if (test_bit(AFS_VNODE_DELETED, &vnode->flags))
goto error;
#ifdef AFS_CACHING_SUPPORT
/* is it cached? */
ret = cachefs_read_or_alloc_page(vnode->cache,
#ifdef CONFIG_AFS_FSCACHE
ret = fscache_read_or_alloc_page(vnode->cache,
page,
afs_file_readpage_read_complete,
NULL,
@ -171,20 +156,21 @@ static int afs_readpage(struct file *file, struct page *page)
#else
ret = -ENOBUFS;
#endif
switch (ret) {
/* read BIO submitted and wb-journal entry found */
case 1:
BUG(); // TODO - handle wb-journal match
/* read BIO submitted (page in cache) */
case 0:
break;
/* no page available in cache */
case -ENOBUFS:
/* page not yet cached */
case -ENODATA:
_debug("cache said ENODATA");
goto go_on;
/* page will not be cached */
case -ENOBUFS:
_debug("cache said ENOBUFS");
default:
go_on:
offset = page->index << PAGE_CACHE_SHIFT;
len = min_t(size_t, i_size_read(inode) - offset, PAGE_SIZE);
@ -198,27 +184,25 @@ static int afs_readpage(struct file *file, struct page *page)
set_bit(AFS_VNODE_DELETED, &vnode->flags);
ret = -ESTALE;
}
#ifdef AFS_CACHING_SUPPORT
cachefs_uncache_page(vnode->cache, page);
#ifdef CONFIG_AFS_FSCACHE
fscache_uncache_page(vnode->cache, page);
#endif
BUG_ON(PageFsCache(page));
goto error;
}
SetPageUptodate(page);
#ifdef AFS_CACHING_SUPPORT
if (cachefs_write_page(vnode->cache,
page,
afs_file_readpage_write_complete,
NULL,
GFP_KERNEL) != 0
) {
cachefs_uncache_page(vnode->cache, page);
unlock_page(page);
/* send the page to the cache */
#ifdef CONFIG_AFS_FSCACHE
if (PageFsCache(page) &&
fscache_write_page(vnode->cache, page, GFP_KERNEL) != 0) {
fscache_uncache_page(vnode->cache, page);
BUG_ON(PageFsCache(page));
}
#else
unlock_page(page);
#endif
unlock_page(page);
}
_leave(" = 0");
@ -232,34 +216,59 @@ static int afs_readpage(struct file *file, struct page *page)
}
/*
* invalidate part or all of a page
* read a set of pages
*/
static void afs_invalidatepage(struct page *page, unsigned long offset)
static int afs_readpages(struct file *file, struct address_space *mapping,
struct list_head *pages, unsigned nr_pages)
{
int ret = 1;
struct afs_vnode *vnode;
int ret = 0;
_enter("{%lu},%lu", page->index, offset);
_enter(",{%lu},,%d", mapping->host->i_ino, nr_pages);
BUG_ON(!PageLocked(page));
if (PagePrivate(page)) {
/* We release buffers only if the entire page is being
* invalidated.
* The get_block cached value has been unconditionally
* invalidated, so real IO is not possible anymore.
*/
if (offset == 0) {
BUG_ON(!PageLocked(page));
ret = 0;
if (!PageWriteback(page))
ret = page->mapping->a_ops->releasepage(page,
0);
/* possibly should BUG_ON(!ret); - neilb */
}
vnode = AFS_FS_I(mapping->host);
if (vnode->flags & AFS_VNODE_DELETED) {
_leave(" = -ESTALE");
return -ESTALE;
}
_leave(" = %d", ret);
/* attempt to read as many of the pages as possible */
#ifdef CONFIG_AFS_FSCACHE
ret = fscache_read_or_alloc_pages(vnode->cache,
mapping,
pages,
&nr_pages,
afs_file_readpage_read_complete,
NULL,
mapping_gfp_mask(mapping));
#else
ret = -ENOBUFS;
#endif
switch (ret) {
/* all pages are being read from the cache */
case 0:
BUG_ON(!list_empty(pages));
BUG_ON(nr_pages != 0);
_leave(" = 0 [reading all]");
return 0;
/* there were pages that couldn't be read from the cache */
case -ENODATA:
case -ENOBUFS:
break;
/* other error */
default:
_leave(" = %d", ret);
return ret;
}
/* load the missing pages from the network */
ret = read_cache_pages(mapping, pages, (void *) afs_readpage, file);
_leave(" = %d [netting]", ret);
return ret;
}
/*
@ -273,25 +282,82 @@ static int afs_launder_page(struct page *page)
}
/*
* release a page and cleanup its private data
* invalidate part or all of a page
* - release a page and clean up its private data if offset is 0 (indicating
* the entire page)
*/
static void afs_invalidatepage(struct page *page, unsigned long offset)
{
struct afs_writeback *wb = (struct afs_writeback *) page_private(page);
_enter("{%lu},%lu", page->index, offset);
BUG_ON(!PageLocked(page));
/* we clean up only if the entire page is being invalidated */
if (offset == 0) {
#ifdef CONFIG_AFS_FSCACHE
if (PageFsCache(page)) {
struct afs_vnode *vnode = AFS_FS_I(page->mapping->host);
fscache_wait_on_page_write(vnode->cache, page);
fscache_uncache_page(vnode->cache, page);
ClearPageFsCache(page);
}
#endif
if (PagePrivate(page)) {
if (wb && !PageWriteback(page)) {
set_page_private(page, 0);
afs_put_writeback(wb);
}
if (!page_private(page))
ClearPagePrivate(page);
}
}
_leave("");
}
/*
* release a page and clean up its private state if it's not busy
* - return true if the page can now be released, false if not
*/
static int afs_releasepage(struct page *page, gfp_t gfp_flags)
{
struct afs_writeback *wb = (struct afs_writeback *) page_private(page);
struct afs_vnode *vnode = AFS_FS_I(page->mapping->host);
struct afs_writeback *wb;
_enter("{{%x:%u}[%lu],%lx},%x",
vnode->fid.vid, vnode->fid.vnode, page->index, page->flags,
gfp_flags);
/* deny if page is being written to the cache and the caller hasn't
* elected to wait */
#ifdef CONFIG_AFS_FSCACHE
if (PageFsCache(page)) {
if (fscache_check_page_write(vnode->cache, page)) {
if (!(gfp_flags & __GFP_WAIT)) {
_leave(" = F [cache busy]");
return 0;
}
fscache_wait_on_page_write(vnode->cache, page);
}
fscache_uncache_page(vnode->cache, page);
ClearPageFsCache(page);
}
#endif
if (PagePrivate(page)) {
wb = (struct afs_writeback *) page_private(page);
ASSERT(wb != NULL);
set_page_private(page, 0);
if (wb) {
set_page_private(page, 0);
afs_put_writeback(wb);
}
ClearPagePrivate(page);
afs_put_writeback(wb);
}
_leave(" = 0");
return 0;
/* indicate that the page can be released */
_leave(" = T");
return 1;
}

31
fs/afs/inode.c
View File

@ -61,6 +61,11 @@ static int afs_inode_map_status(struct afs_vnode *vnode, struct key *key)
return -EBADMSG;
}
#ifdef CONFIG_AFS_FSCACHE
if (vnode->status.size != inode->i_size)
fscache_attr_changed(vnode->cache);
#endif
inode->i_nlink = vnode->status.nlink;
inode->i_uid = vnode->status.owner;
inode->i_gid = 0;
@ -149,15 +154,6 @@ struct inode *afs_iget(struct super_block *sb, struct key *key,
return inode;
}
#ifdef AFS_CACHING_SUPPORT
/* set up caching before reading the status, as fetch-status reads the
* first page of symlinks to see if they're really mntpts */
cachefs_acquire_cookie(vnode->volume->cache,
NULL,
vnode,
&vnode->cache);
#endif
if (!status) {
/* it's a remotely extant inode */
set_bit(AFS_VNODE_CB_BROKEN, &vnode->flags);
@ -183,6 +179,15 @@ struct inode *afs_iget(struct super_block *sb, struct key *key,
}
}
/* set up caching before mapping the status, as map-status reads the
* first page of symlinks to see if they're really mountpoints */
inode->i_size = vnode->status.size;
#ifdef CONFIG_AFS_FSCACHE
vnode->cache = fscache_acquire_cookie(vnode->volume->cache,
&afs_vnode_cache_index_def,
vnode);
#endif
ret = afs_inode_map_status(vnode, key);
if (ret < 0)
goto bad_inode;
@ -196,6 +201,10 @@ struct inode *afs_iget(struct super_block *sb, struct key *key,
/* failure */
bad_inode:
#ifdef CONFIG_AFS_FSCACHE
fscache_relinquish_cookie(vnode->cache, 0);
vnode->cache = NULL;
#endif
iget_failed(inode);
_leave(" = %d [bad]", ret);
return ERR_PTR(ret);
@ -340,8 +349,8 @@ void afs_clear_inode(struct inode *inode)
ASSERT(list_empty(&vnode->writebacks));
ASSERT(!vnode->cb_promised);
#ifdef AFS_CACHING_SUPPORT
cachefs_relinquish_cookie(vnode->cache, 0);
#ifdef CONFIG_AFS_FSCACHE
fscache_relinquish_cookie(vnode->cache, 0);
vnode->cache = NULL;
#endif

53
fs/afs/internal.h
View File

@ -21,6 +21,7 @@
#include "afs.h"
#include "afs_vl.h"
#include "cache.h"
#define AFS_CELL_MAX_ADDRS 15
@ -193,8 +194,8 @@ struct afs_cell {
struct key *anonymous_key; /* anonymous user key for this cell */
struct list_head proc_link; /* /proc cell list link */
struct proc_dir_entry *proc_dir; /* /proc dir for this cell */
#ifdef AFS_CACHING_SUPPORT
struct cachefs_cookie *cache; /* caching cookie */
#ifdef CONFIG_AFS_FSCACHE
struct fscache_cookie *cache; /* caching cookie */
#endif
/* server record management */
@ -249,8 +250,8 @@ struct afs_vlocation {
struct list_head grave; /* link in master graveyard list */
struct list_head update; /* link in master update list */
struct afs_cell *cell; /* cell to which volume belongs */
#ifdef AFS_CACHING_SUPPORT
struct cachefs_cookie *cache; /* caching cookie */
#ifdef CONFIG_AFS_FSCACHE
struct fscache_cookie *cache; /* caching cookie */
#endif
struct afs_cache_vlocation vldb; /* volume information DB record */
struct afs_volume *vols[3]; /* volume access record pointer (index by type) */
@ -302,8 +303,8 @@ struct afs_volume {
atomic_t usage;
struct afs_cell *cell; /* cell to which belongs (unrefd ptr) */
struct afs_vlocation *vlocation; /* volume location */
#ifdef AFS_CACHING_SUPPORT
struct cachefs_cookie *cache; /* caching cookie */
#ifdef CONFIG_AFS_FSCACHE
struct fscache_cookie *cache; /* caching cookie */
#endif
afs_volid_t vid; /* volume ID */
afs_voltype_t type; /* type of volume */
@ -333,8 +334,8 @@ struct afs_vnode {
struct afs_server *server; /* server currently supplying this file */
struct afs_fid fid; /* the file identifier for this inode */
struct afs_file_status status; /* AFS status info for this file */
#ifdef AFS_CACHING_SUPPORT
struct cachefs_cookie *cache; /* caching cookie */
#ifdef CONFIG_AFS_FSCACHE
struct fscache_cookie *cache; /* caching cookie */
#endif
struct afs_permits *permits; /* cache of permits so far obtained */
struct mutex permits_lock; /* lock for altering permits list */
@ -427,6 +428,22 @@ struct afs_uuid {
};
/*****************************************************************************/
/*
* cache.c
*/
#ifdef CONFIG_AFS_FSCACHE
extern struct fscache_netfs afs_cache_netfs;
extern struct fscache_cookie_def afs_cell_cache_index_def;
extern struct fscache_cookie_def afs_vlocation_cache_index_def;
extern struct fscache_cookie_def afs_volume_cache_index_def;
extern struct fscache_cookie_def afs_vnode_cache_index_def;
#else
#define afs_cell_cache_index_def (*(struct fscache_cookie_def *) NULL)
#define afs_vlocation_cache_index_def (*(struct fscache_cookie_def *) NULL)
#define afs_volume_cache_index_def (*(struct fscache_cookie_def *) NULL)
#define afs_vnode_cache_index_def (*(struct fscache_cookie_def *) NULL)
#endif
/*
* callback.c
*/
@ -446,9 +463,6 @@ extern void afs_callback_update_kill(void);
*/
extern struct rw_semaphore afs_proc_cells_sem;
extern struct list_head afs_proc_cells;
#ifdef AFS_CACHING_SUPPORT
extern struct cachefs_index_def afs_cache_cell_index_def;
#endif
#define afs_get_cell(C) do { atomic_inc(&(C)->usage); } while(0)
extern int afs_cell_init(char *);
@ -554,9 +568,6 @@ extern void afs_clear_inode(struct inode *);
* main.c
*/
extern struct afs_uuid afs_uuid;
#ifdef AFS_CACHING_SUPPORT
extern struct cachefs_netfs afs_cache_netfs;
#endif
/*
* misc.c
@ -637,10 +648,6 @@ extern int afs_get_MAC_address(u8 *, size_t);
/*
* vlclient.c
*/
#ifdef AFS_CACHING_SUPPORT
extern struct cachefs_index_def afs_vlocation_cache_index_def;
#endif
extern int afs_vl_get_entry_by_name(struct in_addr *, struct key *,
const char *, struct afs_cache_vlocation *,
const struct afs_wait_mode *);
@ -664,12 +671,6 @@ extern void afs_vlocation_purge(void);
/*
* vnode.c
*/
#ifdef AFS_CACHING_SUPPORT
extern struct cachefs_index_def afs_vnode_cache_index_def;
#endif
extern struct afs_timer_ops afs_vnode_cb_timed_out_ops;
static inline struct afs_vnode *AFS_FS_I(struct inode *inode)
{
return container_of(inode, struct afs_vnode, vfs_inode);
@ -711,10 +712,6 @@ extern int afs_vnode_release_lock(struct afs_vnode *, struct key *);
/*
* volume.c
*/
#ifdef AFS_CACHING_SUPPORT
extern struct cachefs_index_def afs_volume_cache_index_def;
#endif
#define afs_get_volume(V) do { atomic_inc(&(V)->usage); } while(0)
extern void afs_put_volume(struct afs_volume *);

27
fs/afs/main.c
View File

@ -1,6 +1,6 @@
/* AFS client file system
*
* Copyright (C) 2002 Red Hat, Inc. All Rights Reserved.
* Copyright (C) 2002,5 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
@ -29,18 +29,6 @@ static char *rootcell;
module_param(rootcell, charp, 0);
MODULE_PARM_DESC(rootcell, "root AFS cell name and VL server IP addr list");
#ifdef AFS_CACHING_SUPPORT
static struct cachefs_netfs_operations afs_cache_ops = {
.get_page_cookie = afs_cache_get_page_cookie,
};
struct cachefs_netfs afs_cache_netfs = {
.name = "afs",
.version = 0,
.ops = &afs_cache_ops,
};
#endif
struct afs_uuid afs_uuid;
/*
@ -104,10 +92,9 @@ static int __init afs_init(void)
if (ret < 0)
return ret;
#ifdef AFS_CACHING_SUPPORT
#ifdef CONFIG_AFS_FSCACHE
/* we want to be able to cache */
ret = cachefs_register_netfs(&afs_cache_netfs,
&afs_cache_cell_index_def);
ret = fscache_register_netfs(&afs_cache_netfs);
if (ret < 0)
goto error_cache;
#endif
@ -142,8 +129,8 @@ static int __init afs_init(void)
error_open_socket:
error_vl_update_init:
error_cell_init:
#ifdef AFS_CACHING_SUPPORT
cachefs_unregister_netfs(&afs_cache_netfs);
#ifdef CONFIG_AFS_FSCACHE
fscache_unregister_netfs(&afs_cache_netfs);
error_cache:
#endif
afs_callback_update_kill();
@ -175,8 +162,8 @@ static void __exit afs_exit(void)
afs_vlocation_purge();
flush_scheduled_work();
afs_cell_purge();
#ifdef AFS_CACHING_SUPPORT
cachefs_unregister_netfs(&afs_cache_netfs);
#ifdef CONFIG_AFS_FSCACHE
fscache_unregister_netfs(&afs_cache_netfs);
#endif
afs_proc_cleanup();
rcu_barrier();

4
fs/afs/mntpt.c
View File

@ -173,9 +173,9 @@ static struct vfsmount *afs_mntpt_do_automount(struct dentry *mntpt)
if (PageError(page))
goto error;
buf = kmap(page);
buf = kmap_atomic(page, KM_USER0);
memcpy(devname, buf, size);
kunmap(page);
kunmap_atomic(buf, KM_USER0);
page_cache_release(page);
page = NULL;

25
fs/afs/vlocation.c
View File

@ -281,9 +281,8 @@ static void afs_vlocation_apply_update(struct afs_vlocation *vl,
vl->vldb = *vldb;
#ifdef AFS_CACHING_SUPPORT
/* update volume entry in local cache */
cachefs_update_cookie(vl->cache);
#ifdef CONFIG_AFS_FSCACHE
fscache_update_cookie(vl->cache);
#endif
}
@ -304,11 +303,9 @@ static int afs_vlocation_fill_in_record(struct afs_vlocation *vl,
memset(&vldb, 0, sizeof(vldb));
/* see if we have an in-cache copy (will set vl->valid if there is) */
#ifdef AFS_CACHING_SUPPORT
cachefs_acquire_cookie(cell->cache,
&afs_volume_cache_index_def,
vlocation,
&vl->cache);
#ifdef CONFIG_AFS_FSCACHE
vl->cache = fscache_acquire_cookie(vl->cell->cache,
&afs_vlocation_cache_index_def, vl);
#endif
if (vl->valid) {
@ -420,6 +417,11 @@ struct afs_vlocation *afs_vlocation_lookup(struct afs_cell *cell,
spin_unlock(&vl->lock);
wake_up(&vl->waitq);
/* update volume entry in local cache */
#ifdef CONFIG_AFS_FSCACHE
fscache_update_cookie(vl->cache);
#endif
/* schedule for regular updates */
afs_vlocation_queue_for_updates(vl);
goto success;
@ -465,7 +467,7 @@ struct afs_vlocation *afs_vlocation_lookup(struct afs_cell *cell,
spin_unlock(&vl->lock);
success:
_leave(" = %p",vl);
_leave(" = %p", vl);
return vl;
error_abandon:
@ -523,10 +525,9 @@ static void afs_vlocation_destroy(struct afs_vlocation *vl)
{
_enter("%p", vl);
#ifdef AFS_CACHING_SUPPORT
cachefs_relinquish_cookie(vl->cache, 0);
#ifdef CONFIG_AFS_FSCACHE
fscache_relinquish_cookie(vl->cache, 0);
#endif
afs_put_cell(vl->cell);
kfree(vl);
}

14
fs/afs/volume.c
View File

@ -124,13 +124,11 @@ struct afs_volume *afs_volume_lookup(struct afs_mount_params *params)
}
/* attach the cache and volume location */
#ifdef AFS_CACHING_SUPPORT
cachefs_acquire_cookie(vlocation->cache,
&afs_vnode_cache_index_def,
volume,
&volume->cache);
#ifdef CONFIG_AFS_FSCACHE
volume->cache = fscache_acquire_cookie(vlocation->cache,
&afs_volume_cache_index_def,
volume);
#endif
afs_get_vlocation(vlocation);
volume->vlocation = vlocation;
@ -194,8 +192,8 @@ void afs_put_volume(struct afs_volume *volume)
up_write(&vlocation->cell->vl_sem);
/* finish cleaning up the volume */
#ifdef AFS_CACHING_SUPPORT
cachefs_relinquish_cookie(volume->cache, 0);
#ifdef CONFIG_AFS_FSCACHE
fscache_relinquish_cookie(volume->cache, 0);
#endif
afs_put_vlocation(vlocation);

21
fs/afs/write.c
View File

@ -780,3 +780,24 @@ int afs_fsync(struct file *file, struct dentry *dentry, int datasync)
_leave(" = %d", ret);
return ret;
}
/*
* notification that a previously read-only page is about to become writable
* - if it returns an error, the caller will deliver a bus error signal
*/
int afs_page_mkwrite(struct vm_area_struct *vma, struct page *page)
{
struct afs_vnode *vnode = AFS_FS_I(vma->vm_file->f_mapping->host);
_enter("{{%x:%u}},{%lx}",
vnode->fid.vid, vnode->fid.vnode, page->index);
/* wait for the page to be written to the cache before we allow it to
* be modified */
#ifdef CONFIG_AFS_FSCACHE
fscache_wait_on_page_write(vnode->cache, page);
#endif
_leave(" = 0");
return 0;
}

39
fs/cachefiles/Kconfig Normal file
View File

@ -0,0 +1,39 @@
config CACHEFILES
tristate "Filesystem caching on files"
depends on FSCACHE && BLOCK
help
This permits use of a mounted filesystem as a cache for other
filesystems - primarily networking filesystems - thus allowing fast
local disk to enhance the speed of slower devices.
See Documentation/filesystems/caching/cachefiles.txt for more
information.
config CACHEFILES_DEBUG
bool "Debug CacheFiles"
depends on CACHEFILES
help
This permits debugging to be dynamically enabled in the filesystem
caching on files module. If this is set, the debugging output may be
enabled by setting bits in /sys/modules/cachefiles/parameter/debug or
by including a debugging specifier in /etc/cachefilesd.conf.
config CACHEFILES_HISTOGRAM
bool "Gather latency information on CacheFiles"
depends on CACHEFILES && PROC_FS
help
This option causes latency information to be gathered on CacheFiles
operation and exported through file:
/proc/fs/cachefiles/histogram
The generation of this histogram adds a certain amount of overhead to
execution as there are a number of points at which data is gathered,
and on a multi-CPU system these may be on cachelines that keep
bouncing between CPUs. On the other hand, the histogram may be
useful for debugging purposes. Saying 'N' here is recommended.
See Documentation/filesystems/caching/cachefiles.txt for more
information.

18
fs/cachefiles/Makefile Normal file
View File

@ -0,0 +1,18 @@
#
# Makefile for caching in a mounted filesystem
#
cachefiles-y := \
bind.o \
daemon.o \
interface.o \
key.o \
main.o \
namei.o \
rdwr.o \
security.o \
xattr.o
cachefiles-$(CONFIG_CACHEFILES_HISTOGRAM) += proc.o
obj-$(CONFIG_CACHEFILES) := cachefiles.o

286
fs/cachefiles/bind.c Normal file
View File

@ -0,0 +1,286 @@
/* Bind and unbind a cache from the filesystem backing it
*
* Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public Licence
* as published by the Free Software Foundation; either version
* 2 of the Licence, or (at your option) any later version.
*/
#include <linux/module.h>
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/completion.h>
#include <linux/slab.h>
#include <linux/fs.h>
#include <linux/file.h>
#include <linux/namei.h>
#include <linux/mount.h>
#include <linux/statfs.h>
#include <linux/ctype.h>
#include "internal.h"
static int cachefiles_daemon_add_cache(struct cachefiles_cache *caches);
/*
* bind a directory as a cache
*/
int cachefiles_daemon_bind(struct cachefiles_cache *cache, char *args)
{
_enter("{%u,%u,%u,%u,%u,%u},%s",
cache->frun_percent,
cache->fcull_percent,
cache->fstop_percent,
cache->brun_percent,
cache->bcull_percent,
cache->bstop_percent,
args);
/* start by checking things over */
ASSERT(cache->fstop_percent >= 0 &&
cache->fstop_percent < cache->fcull_percent &&
cache->fcull_percent < cache->frun_percent &&
cache->frun_percent < 100);
ASSERT(cache->bstop_percent >= 0 &&
cache->bstop_percent < cache->bcull_percent &&
cache->bcull_percent < cache->brun_percent &&
cache->brun_percent < 100);
if (*args) {
kerror("'bind' command doesn't take an argument");
return -EINVAL;
}
if (!cache->rootdirname) {
kerror("No cache directory specified");
return -EINVAL;
}
/* don't permit already bound caches to be re-bound */
if (test_bit(CACHEFILES_READY, &cache->flags)) {
kerror("Cache already bound");
return -EBUSY;
}
/* make sure we have copies of the tag and dirname strings */
if (!cache->tag) {
/* the tag string is released by the fops->release()
* function, so we don't release it on error here */
cache->tag = kstrdup("CacheFiles", GFP_KERNEL);
if (!cache->tag)
return -ENOMEM;
}
/* add the cache */
return cachefiles_daemon_add_cache(cache);
}
/*
* add a cache
*/
static int cachefiles_daemon_add_cache(struct cachefiles_cache *cache)
{
struct cachefiles_object *fsdef;
struct nameidata nd;
struct kstatfs stats;
struct dentry *graveyard, *cachedir, *root;
const struct cred *saved_cred;
int ret;
_enter("");
/* we want to work under the module's security ID */
ret = cachefiles_get_security_ID(cache);
if (ret < 0)
return ret;
cachefiles_begin_secure(cache, &saved_cred);
/* allocate the root index object */
ret = -ENOMEM;
fsdef = kmem_cache_alloc(cachefiles_object_jar, GFP_KERNEL);
if (!fsdef)
goto error_root_object;
ASSERTCMP(fsdef->backer, ==, NULL);
atomic_set(&fsdef->usage, 1);
fsdef->type = FSCACHE_COOKIE_TYPE_INDEX;
_debug("- fsdef %p", fsdef);
/* look up the directory at the root of the cache */
memset(&nd, 0, sizeof(nd));
ret = path_lookup(cache->rootdirname, LOOKUP_DIRECTORY, &nd);
if (ret < 0)
goto error_open_root;
cache->mnt = mntget(nd.path.mnt);
root = dget(nd.path.dentry);
path_put(&nd.path);
/* check parameters */
ret = -EOPNOTSUPP;
if (!root->d_inode ||
!root->d_inode->i_op ||
!root->d_inode->i_op->lookup ||
!root->d_inode->i_op->mkdir ||
!root->d_inode->i_op->setxattr ||
!root->d_inode->i_op->getxattr ||
!root->d_sb ||
!root->d_sb->s_op ||
!root->d_sb->s_op->statfs ||
!root->d_sb->s_op->sync_fs)
goto error_unsupported;
ret = -EROFS;
if (root->d_sb->s_flags & MS_RDONLY)
goto error_unsupported;
/* determine the security of the on-disk cache as this governs
* security ID of files we create */
ret = cachefiles_determine_cache_security(cache, root, &saved_cred);
if (ret < 0)
goto error_unsupported;
/* get the cache size and blocksize */
ret = vfs_statfs(root, &stats);
if (ret < 0)
goto error_unsupported;
ret = -ERANGE;
if (stats.f_bsize <= 0)
goto error_unsupported;
ret = -EOPNOTSUPP;
if (stats.f_bsize > PAGE_SIZE)
goto error_unsupported;
cache->bsize = stats.f_bsize;
cache->bshift = 0;
if (stats.f_bsize < PAGE_SIZE)
cache->bshift = PAGE_SHIFT - ilog2(stats.f_bsize);
_debug("blksize %u (shift %u)",
cache->bsize, cache->bshift);
_debug("size %llu, avail %llu",
(unsigned long long) stats.f_blocks,
(unsigned long long) stats.f_bavail);
/* set up caching limits */
do_div(stats.f_files, 100);
cache->fstop = stats.f_files * cache->fstop_percent;
cache->fcull = stats.f_files * cache->fcull_percent;
cache->frun = stats.f_files * cache->frun_percent;
_debug("limits {%llu,%llu,%llu} files",
(unsigned long long) cache->frun,
(unsigned long long) cache->fcull,
(unsigned long long) cache->fstop);
stats.f_blocks >>= cache->bshift;
do_div(stats.f_blocks, 100);
cache->bstop = stats.f_blocks * cache->bstop_percent;
cache->bcull = stats.f_blocks * cache->bcull_percent;
cache->brun = stats.f_blocks * cache->brun_percent;
_debug("limits {%llu,%llu,%llu} blocks",
(unsigned long long) cache->brun,
(unsigned long long) cache->bcull,
(unsigned long long) cache->bstop);
/* get the cache directory and check its type */
cachedir = cachefiles_get_directory(cache, root, "cache");
if (IS_ERR(cachedir)) {
ret = PTR_ERR(cachedir);
goto error_unsupported;
}
fsdef->dentry = cachedir;
fsdef->fscache.cookie = NULL;
ret = cachefiles_check_object_type(fsdef);
if (ret < 0)
goto error_unsupported;
/* get the graveyard directory */
graveyard = cachefiles_get_directory(cache, root, "graveyard");
if (IS_ERR(graveyard)) {
ret = PTR_ERR(graveyard);
goto error_unsupported;
}
cache->graveyard = graveyard;
/* publish the cache */
fscache_init_cache(&cache->cache,
&cachefiles_cache_ops,
"%s",
fsdef->dentry->d_sb->s_id);
fscache_object_init(&fsdef->fscache, NULL, &cache->cache);
ret = fscache_add_cache(&cache->cache, &fsdef->fscache, cache->tag);
if (ret < 0)
goto error_add_cache;
/* done */
set_bit(CACHEFILES_READY, &cache->flags);
dput(root);
printk(KERN_INFO "CacheFiles:"
" File cache on %s registered\n",
cache->cache.identifier);
/* check how much space the cache has */
cachefiles_has_space(cache, 0, 0);
cachefiles_end_secure(cache, saved_cred);
return 0;
error_add_cache:
dput(cache->graveyard);
cache->graveyard = NULL;
error_unsupported:
mntput(cache->mnt);
cache->mnt = NULL;
dput(fsdef->dentry);
fsdef->dentry = NULL;
dput(root);
error_open_root:
kmem_cache_free(cachefiles_object_jar, fsdef);
error_root_object:
cachefiles_end_secure(cache, saved_cred);
kerror("Failed to register: %d", ret);
return ret;
}
/*
* unbind a cache on fd release
*/
void cachefiles_daemon_unbind(struct cachefiles_cache *cache)
{
_enter("");
if (test_bit(CACHEFILES_READY, &cache->flags)) {
printk(KERN_INFO "CacheFiles:"
" File cache on %s unregistering\n",
cache->cache.identifier);
fscache_withdraw_cache(&cache->cache);
}
dput(cache->graveyard);
mntput(cache->mnt);
kfree(cache->rootdirname);
kfree(cache->secctx);
kfree(cache->tag);
_leave("");
}

755
fs/cachefiles/daemon.c Normal file
View File

@ -0,0 +1,755 @@
/* Daemon interface
*
* Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public Licence
* as published by the Free Software Foundation; either version
* 2 of the Licence, or (at your option) any later version.
*/
#include <linux/module.h>
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/completion.h>
#include <linux/slab.h>
#include <linux/fs.h>
#include <linux/file.h>
#include <linux/namei.h>
#include <linux/poll.h>
#include <linux/mount.h>
#include <linux/statfs.h>
#include <linux/ctype.h>
#include <linux/fs_struct.h>
#include "internal.h"
static int cachefiles_daemon_open(struct inode *, struct file *);
static int cachefiles_daemon_release(struct inode *, struct file *);
static ssize_t cachefiles_daemon_read(struct file *, char __user *, size_t,
loff_t *);
static ssize_t cachefiles_daemon_write(struct file *, const char __user *,
size_t, loff_t *);
static unsigned int cachefiles_daemon_poll(struct file *,
struct poll_table_struct *);
static int cachefiles_daemon_frun(struct cachefiles_cache *, char *);
static int cachefiles_daemon_fcull(struct cachefiles_cache *, char *);
static int cachefiles_daemon_fstop(struct cachefiles_cache *, char *);
static int cachefiles_daemon_brun(struct cachefiles_cache *, char *);
static int cachefiles_daemon_bcull(struct cachefiles_cache *, char *);
static int cachefiles_daemon_bstop(struct cachefiles_cache *, char *);
static int cachefiles_daemon_cull(struct cachefiles_cache *, char *);
static int cachefiles_daemon_debug(struct cachefiles_cache *, char *);
static int cachefiles_daemon_dir(struct cachefiles_cache *, char *);
static int cachefiles_daemon_inuse(struct cachefiles_cache *, char *);
static int cachefiles_daemon_secctx(struct cachefiles_cache *, char *);
static int cachefiles_daemon_tag(struct cachefiles_cache *, char *);
static unsigned long cachefiles_open;
const struct file_operations cachefiles_daemon_fops = {
.owner = THIS_MODULE,
.open = cachefiles_daemon_open,
.release = cachefiles_daemon_release,
.read = cachefiles_daemon_read,
.write = cachefiles_daemon_write,
.poll = cachefiles_daemon_poll,
};
struct cachefiles_daemon_cmd {
char name[8];
int (*handler)(struct cachefiles_cache *cache, char *args);
};
static const struct cachefiles_daemon_cmd cachefiles_daemon_cmds[] = {
{ "bind", cachefiles_daemon_bind },
{ "brun", cachefiles_daemon_brun },
{ "bcull", cachefiles_daemon_bcull },
{ "bstop", cachefiles_daemon_bstop },
{ "cull", cachefiles_daemon_cull },
{ "debug", cachefiles_daemon_debug },
{ "dir", cachefiles_daemon_dir },
{ "frun", cachefiles_daemon_frun },
{ "fcull", cachefiles_daemon_fcull },
{ "fstop", cachefiles_daemon_fstop },
{ "inuse", cachefiles_daemon_inuse },
{ "secctx", cachefiles_daemon_secctx },
{ "tag", cachefiles_daemon_tag },
{ "", NULL }
};
/*
* do various checks
*/
static int cachefiles_daemon_open(struct inode *inode, struct file *file)
{
struct cachefiles_cache *cache;
_enter("");
/* only the superuser may do this */
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
/* the cachefiles device may only be open once at a time */
if (xchg(&cachefiles_open, 1) == 1)
return -EBUSY;
/* allocate a cache record */
cache = kzalloc(sizeof(struct cachefiles_cache), GFP_KERNEL);
if (!cache) {
cachefiles_open = 0;
return -ENOMEM;
}
mutex_init(&cache->daemon_mutex);
cache->active_nodes = RB_ROOT;
rwlock_init(&cache->active_lock);
init_waitqueue_head(&cache->daemon_pollwq);
/* set default caching limits
* - limit at 1% free space and/or free files
* - cull below 5% free space and/or free files
* - cease culling above 7% free space and/or free files
*/
cache->frun_percent = 7;
cache->fcull_percent = 5;
cache->fstop_percent = 1;
cache->brun_percent = 7;
cache->bcull_percent = 5;
cache->bstop_percent = 1;
file->private_data = cache;
cache->cachefilesd = file;
return 0;
}
/*
* release a cache
*/
static int cachefiles_daemon_release(struct inode *inode, struct file *file)
{
struct cachefiles_cache *cache = file->private_data;
_enter("");
ASSERT(cache);
set_bit(CACHEFILES_DEAD, &cache->flags);
cachefiles_daemon_unbind(cache);
ASSERT(!cache->active_nodes.rb_node);
/* clean up the control file interface */
cache->cachefilesd = NULL;
file->private_data = NULL;
cachefiles_open = 0;
kfree(cache);
_leave("");
return 0;
}
/*
* read the cache state
*/
static ssize_t cachefiles_daemon_read(struct file *file, char __user *_buffer,
size_t buflen, loff_t *pos)
{
struct cachefiles_cache *cache = file->private_data;
char buffer[256];
int n;
//_enter(",,%zu,", buflen);
if (!test_bit(CACHEFILES_READY, &cache->flags))
return 0;
/* check how much space the cache has */
cachefiles_has_space(cache, 0, 0);
/* summarise */
clear_bit(CACHEFILES_STATE_CHANGED, &cache->flags);
n = snprintf(buffer, sizeof(buffer),
"cull=%c"
" frun=%llx"
" fcull=%llx"
" fstop=%llx"
" brun=%llx"
" bcull=%llx"
" bstop=%llx",
test_bit(CACHEFILES_CULLING, &cache->flags) ? '1' : '0',
(unsigned long long) cache->frun,
(unsigned long long) cache->fcull,
(unsigned long long) cache->fstop,
(unsigned long long) cache->brun,
(unsigned long long) cache->bcull,
(unsigned long long) cache->bstop
);
if (n > buflen)
return -EMSGSIZE;
if (copy_to_user(_buffer, buffer, n) != 0)
return -EFAULT;
return n;
}
/*
* command the cache
*/
static ssize_t cachefiles_daemon_write(struct file *file,
const char __user *_data,
size_t datalen,
loff_t *pos)
{
const struct cachefiles_daemon_cmd *cmd;
struct cachefiles_cache *cache = file->private_data;
ssize_t ret;
char *data, *args, *cp;
//_enter(",,%zu,", datalen);
ASSERT(cache);
if (test_bit(CACHEFILES_DEAD, &cache->flags))
return -EIO;
if (datalen < 0 || datalen > PAGE_SIZE - 1)
return -EOPNOTSUPP;
/* drag the command string into the kernel so we can parse it */
data = kmalloc(datalen + 1, GFP_KERNEL);
if (!data)
return -ENOMEM;
ret = -EFAULT;
if (copy_from_user(data, _data, datalen) != 0)
goto error;
data[datalen] = '\0';
ret = -EINVAL;
if (memchr(data, '\0', datalen))
goto error;
/* strip any newline */
cp = memchr(data, '\n', datalen);
if (cp) {
if (cp == data)
goto error;
*cp = '\0';
}
/* parse the command */
ret = -EOPNOTSUPP;
for (args = data; *args; args++)
if (isspace(*args))
break;
if (*args) {
if (args == data)
goto error;
*args = '\0';
for (args++; isspace(*args); args++)
continue;
}
/* run the appropriate command handler */
for (cmd = cachefiles_daemon_cmds; cmd->name[0]; cmd++)
if (strcmp(cmd->name, data) == 0)
goto found_command;
error:
kfree(data);
//_leave(" = %zd", ret);
return ret;
found_command:
mutex_lock(&cache->daemon_mutex);
ret = -EIO;
if (!test_bit(CACHEFILES_DEAD, &cache->flags))
ret = cmd->handler(cache, args);
mutex_unlock(&cache->daemon_mutex);
if (ret == 0)
ret = datalen;
goto error;
}
/*
* poll for culling state
* - use POLLOUT to indicate culling state
*/
static unsigned int cachefiles_daemon_poll(struct file *file,
struct poll_table_struct *poll)
{
struct cachefiles_cache *cache = file->private_data;
unsigned int mask;
poll_wait(file, &cache->daemon_pollwq, poll);
mask = 0;
if (test_bit(CACHEFILES_STATE_CHANGED, &cache->flags))
mask |= POLLIN;
if (test_bit(CACHEFILES_CULLING, &cache->flags))
mask |= POLLOUT;
return mask;
}
/*
* give a range error for cache space constraints
* - can be tail-called
*/
static int cachefiles_daemon_range_error(struct cachefiles_cache *cache,
char *args)
{
kerror("Free space limits must be in range"
" 0%%<=stop<cull<run<100%%");
return -EINVAL;
}
/*
* set the percentage of files at which to stop culling
* - command: "frun <N>%"
*/
static int cachefiles_daemon_frun(struct cachefiles_cache *cache, char *args)
{
unsigned long frun;
_enter(",%s", args);
if (!*args)
return -EINVAL;
frun = simple_strtoul(args, &args, 10);
if (args[0] != '%' || args[1] != '\0')
return -EINVAL;
if (frun <= cache->fcull_percent || frun >= 100)
return cachefiles_daemon_range_error(cache, args);
cache->frun_percent = frun;
return 0;
}
/*
* set the percentage of files at which to start culling
* - command: "fcull <N>%"
*/
static int cachefiles_daemon_fcull(struct cachefiles_cache *cache, char *args)
{
unsigned long fcull;
_enter(",%s", args);
if (!*args)
return -EINVAL;
fcull = simple_strtoul(args, &args, 10);
if (args[0] != '%' || args[1] != '\0')
return -EINVAL;
if (fcull <= cache->fstop_percent || fcull >= cache->frun_percent)
return cachefiles_daemon_range_error(cache, args);
cache->fcull_percent = fcull;
return 0;
}
/*
* set the percentage of files at which to stop allocating
* - command: "fstop <N>%"
*/
static int cachefiles_daemon_fstop(struct cachefiles_cache *cache, char *args)
{
unsigned long fstop;
_enter(",%s", args);
if (!*args)
return -EINVAL;
fstop = simple_strtoul(args, &args, 10);
if (args[0] != '%' || args[1] != '\0')
return -EINVAL;
if (fstop < 0 || fstop >= cache->fcull_percent)
return cachefiles_daemon_range_error(cache, args);
cache->fstop_percent = fstop;
return 0;
}
/*
* set the percentage of blocks at which to stop culling
* - command: "brun <N>%"
*/
static int cachefiles_daemon_brun(struct cachefiles_cache *cache, char *args)
{
unsigned long brun;
_enter(",%s", args);
if (!*args)
return -EINVAL;
brun = simple_strtoul(args, &args, 10);
if (args[0] != '%' || args[1] != '\0')
return -EINVAL;
if (brun <= cache->bcull_percent || brun >= 100)
return cachefiles_daemon_range_error(cache, args);
cache->brun_percent = brun;
return 0;
}
/*
* set the percentage of blocks at which to start culling
* - command: "bcull <N>%"
*/
static int cachefiles_daemon_bcull(struct cachefiles_cache *cache, char *args)
{
unsigned long bcull;
_enter(",%s", args);
if (!*args)
return -EINVAL;
bcull = simple_strtoul(args, &args, 10);
if (args[0] != '%' || args[1] != '\0')
return -EINVAL;
if (bcull <= cache->bstop_percent || bcull >= cache->brun_percent)
return cachefiles_daemon_range_error(cache, args);
cache->bcull_percent = bcull;
return 0;
}
/*
* set the percentage of blocks at which to stop allocating
* - command: "bstop <N>%"
*/
static int cachefiles_daemon_bstop(struct cachefiles_cache *cache, char *args)
{
unsigned long bstop;
_enter(",%s", args);
if (!*args)
return -EINVAL;
bstop = simple_strtoul(args, &args, 10);
if (args[0] != '%' || args[1] != '\0')
return -EINVAL;
if (bstop < 0 || bstop >= cache->bcull_percent)
return cachefiles_daemon_range_error(cache, args);
cache->bstop_percent = bstop;
return 0;
}
/*
* set the cache directory
* - command: "dir <name>"
*/
static int cachefiles_daemon_dir(struct cachefiles_cache *cache, char *args)
{
char *dir;
_enter(",%s", args);
if (!*args) {
kerror("Empty directory specified");
return -EINVAL;
}
if (cache->rootdirname) {
kerror("Second cache directory specified");
return -EEXIST;
}
dir = kstrdup(args, GFP_KERNEL);
if (!dir)
return -ENOMEM;
cache->rootdirname = dir;
return 0;
}
/*
* set the cache security context
* - command: "secctx <ctx>"
*/
static int cachefiles_daemon_secctx(struct cachefiles_cache *cache, char *args)
{
char *secctx;
_enter(",%s", args);
if (!*args) {
kerror("Empty security context specified");
return -EINVAL;
}
if (cache->secctx) {
kerror("Second security context specified");
return -EINVAL;
}
secctx = kstrdup(args, GFP_KERNEL);
if (!secctx)
return -ENOMEM;
cache->secctx = secctx;
return 0;
}
/*
* set the cache tag
* - command: "tag <name>"
*/
static int cachefiles_daemon_tag(struct cachefiles_cache *cache, char *args)
{
char *tag;
_enter(",%s", args);
if (!*args) {
kerror("Empty tag specified");
return -EINVAL;
}
if (cache->tag)
return -EEXIST;
tag = kstrdup(args, GFP_KERNEL);
if (!tag)
return -ENOMEM;
cache->tag = tag;
return 0;
}
/*
* request a node in the cache be culled from the current working directory
* - command: "cull <name>"
*/
static int cachefiles_daemon_cull(struct cachefiles_cache *cache, char *args)
{
struct fs_struct *fs;
struct dentry *dir;
const struct cred *saved_cred;
int ret;
_enter(",%s", args);
if (strchr(args, '/'))
goto inval;
if (!test_bit(CACHEFILES_READY, &cache->flags)) {
kerror("cull applied to unready cache");
return -EIO;
}
if (test_bit(CACHEFILES_DEAD, &cache->flags)) {
kerror("cull applied to dead cache");
return -EIO;
}
/* extract the directory dentry from the cwd */
fs = current->fs;
read_lock(&fs->lock);
dir = dget(fs->pwd.dentry);
read_unlock(&fs->lock);
if (!S_ISDIR(dir->d_inode->i_mode))
goto notdir;
cachefiles_begin_secure(cache, &saved_cred);
ret = cachefiles_cull(cache, dir, args);
cachefiles_end_secure(cache, saved_cred);
dput(dir);
_leave(" = %d", ret);
return ret;
notdir:
dput(dir);
kerror("cull command requires dirfd to be a directory");
return -ENOTDIR;
inval:
kerror("cull command requires dirfd and filename");
return -EINVAL;
}
/*
* set debugging mode
* - command: "debug <mask>"
*/
static int cachefiles_daemon_debug(struct cachefiles_cache *cache, char *args)
{
unsigned long mask;
_enter(",%s", args);
mask = simple_strtoul(args, &args, 0);
if (args[0] != '\0')
goto inval;
cachefiles_debug = mask;
_leave(" = 0");
return 0;
inval:
kerror("debug command requires mask");
return -EINVAL;
}
/*
* find out whether an object in the current working directory is in use or not
* - command: "inuse <name>"
*/
static int cachefiles_daemon_inuse(struct cachefiles_cache *cache, char *args)
{
struct fs_struct *fs;
struct dentry *dir;
const struct cred *saved_cred;
int ret;
//_enter(",%s", args);
if (strchr(args, '/'))
goto inval;
if (!test_bit(CACHEFILES_READY, &cache->flags)) {
kerror("inuse applied to unready cache");
return -EIO;
}
if (test_bit(CACHEFILES_DEAD, &cache->flags)) {
kerror("inuse applied to dead cache");
return -EIO;
}
/* extract the directory dentry from the cwd */
fs = current->fs;
read_lock(&fs->lock);
dir = dget(fs->pwd.dentry);
read_unlock(&fs->lock);
if (!S_ISDIR(dir->d_inode->i_mode))
goto notdir;
cachefiles_begin_secure(cache, &saved_cred);
ret = cachefiles_check_in_use(cache, dir, args);
cachefiles_end_secure(cache, saved_cred);
dput(dir);
//_leave(" = %d", ret);
return ret;
notdir:
dput(dir);
kerror("inuse command requires dirfd to be a directory");
return -ENOTDIR;
inval:
kerror("inuse command requires dirfd and filename");
return -EINVAL;
}
/*
* see if we have space for a number of pages and/or a number of files in the
* cache
*/
int cachefiles_has_space(struct cachefiles_cache *cache,
unsigned fnr, unsigned bnr)
{
struct kstatfs stats;
int ret;
//_enter("{%llu,%llu,%llu,%llu,%llu,%llu},%u,%u",
// (unsigned long long) cache->frun,
// (unsigned long long) cache->fcull,
// (unsigned long long) cache->fstop,
// (unsigned long long) cache->brun,
// (unsigned long long) cache->bcull,
// (unsigned long long) cache->bstop,
// fnr, bnr);
/* find out how many pages of blockdev are available */
memset(&stats, 0, sizeof(stats));
ret = vfs_statfs(cache->mnt->mnt_root, &stats);
if (ret < 0) {
if (ret == -EIO)
cachefiles_io_error(cache, "statfs failed");
_leave(" = %d", ret);
return ret;
}
stats.f_bavail >>= cache->bshift;
//_debug("avail %llu,%llu",
// (unsigned long long) stats.f_ffree,
// (unsigned long long) stats.f_bavail);
/* see if there is sufficient space */
if (stats.f_ffree > fnr)
stats.f_ffree -= fnr;
else
stats.f_ffree = 0;
if (stats.f_bavail > bnr)
stats.f_bavail -= bnr;
else
stats.f_bavail = 0;
ret = -ENOBUFS;
if (stats.f_ffree < cache->fstop ||
stats.f_bavail < cache->bstop)
goto begin_cull;
ret = 0;
if (stats.f_ffree < cache->fcull ||
stats.f_bavail < cache->bcull)
goto begin_cull;
if (test_bit(CACHEFILES_CULLING, &cache->flags) &&
stats.f_ffree >= cache->frun &&
stats.f_bavail >= cache->brun &&
test_and_clear_bit(CACHEFILES_CULLING, &cache->flags)
) {
_debug("cease culling");
cachefiles_state_changed(cache);
}
//_leave(" = 0");
return 0;
begin_cull:
if (!test_and_set_bit(CACHEFILES_CULLING, &cache->flags)) {
_debug("### CULL CACHE ###");
cachefiles_state_changed(cache);
}
_leave(" = %d", ret);
return ret;
}

449
fs/cachefiles/interface.c Normal file
View File

@ -0,0 +1,449 @@
/* FS-Cache interface to CacheFiles
*
* Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public Licence
* as published by the Free Software Foundation; either version
* 2 of the Licence, or (at your option) any later version.
*/
#include <linux/mount.h>
#include <linux/buffer_head.h>
#include "internal.h"
#define list_to_page(head) (list_entry((head)->prev, struct page, lru))
struct cachefiles_lookup_data {
struct cachefiles_xattr *auxdata; /* auxiliary data */
char *key; /* key path */
};
static int cachefiles_attr_changed(struct fscache_object *_object);
/*
* allocate an object record for a cookie lookup and prepare the lookup data
*/
static struct fscache_object *cachefiles_alloc_object(
struct fscache_cache *_cache,
struct fscache_cookie *cookie)
{
struct cachefiles_lookup_data *lookup_data;
struct cachefiles_object *object;
struct cachefiles_cache *cache;
struct cachefiles_xattr *auxdata;
unsigned keylen, auxlen;
void *buffer;
char *key;
cache = container_of(_cache, struct cachefiles_cache, cache);
_enter("{%s},%p,", cache->cache.identifier, cookie);
lookup_data = kmalloc(sizeof(*lookup_data), GFP_KERNEL);
if (!lookup_data)
goto nomem_lookup_data;
/* create a new object record and a temporary leaf image */
object = kmem_cache_alloc(cachefiles_object_jar, GFP_KERNEL);
if (!object)
goto nomem_object;
ASSERTCMP(object->backer, ==, NULL);
BUG_ON(test_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags));
atomic_set(&object->usage, 1);
fscache_object_init(&object->fscache, cookie, &cache->cache);
object->type = cookie->def->type;
/* get hold of the raw key
* - stick the length on the front and leave space on the back for the
* encoder
*/
buffer = kmalloc((2 + 512) + 3, GFP_KERNEL);
if (!buffer)
goto nomem_buffer;
keylen = cookie->def->get_key(cookie->netfs_data, buffer + 2, 512);
ASSERTCMP(keylen, <, 512);
*(uint16_t *)buffer = keylen;
((char *)buffer)[keylen + 2] = 0;
((char *)buffer)[keylen + 3] = 0;
((char *)buffer)[keylen + 4] = 0;
/* turn the raw key into something that can work with as a filename */
key = cachefiles_cook_key(buffer, keylen + 2, object->type);
if (!key)
goto nomem_key;
/* get hold of the auxiliary data and prepend the object type */
auxdata = buffer;
auxlen = 0;
if (cookie->def->get_aux) {
auxlen = cookie->def->get_aux(cookie->netfs_data,
auxdata->data, 511);
ASSERTCMP(auxlen, <, 511);
}
auxdata->len = auxlen + 1;
auxdata->type = cookie->def->type;
lookup_data->auxdata = auxdata;
lookup_data->key = key;
object->lookup_data = lookup_data;
_leave(" = %p [%p]", &object->fscache, lookup_data);
return &object->fscache;
nomem_key:
kfree(buffer);
nomem_buffer:
BUG_ON(test_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags));
kmem_cache_free(cachefiles_object_jar, object);
fscache_object_destroyed(&cache->cache);
nomem_object:
kfree(lookup_data);
nomem_lookup_data:
_leave(" = -ENOMEM");
return ERR_PTR(-ENOMEM);
}
/*
* attempt to look up the nominated node in this cache
*/
static void cachefiles_lookup_object(struct fscache_object *_object)
{
struct cachefiles_lookup_data *lookup_data;
struct cachefiles_object *parent, *object;
struct cachefiles_cache *cache;
const struct cred *saved_cred;
int ret;
_enter("{OBJ%x}", _object->debug_id);
cache = container_of(_object->cache, struct cachefiles_cache, cache);
parent = container_of(_object->parent,
struct cachefiles_object, fscache);
object = container_of(_object, struct cachefiles_object, fscache);
lookup_data = object->lookup_data;
ASSERTCMP(lookup_data, !=, NULL);
/* look up the key, creating any missing bits */
cachefiles_begin_secure(cache, &saved_cred);
ret = cachefiles_walk_to_object(parent, object,
lookup_data->key,
lookup_data->auxdata);
cachefiles_end_secure(cache, saved_cred);
/* polish off by setting the attributes of non-index files */
if (ret == 0 &&
object->fscache.cookie->def->type != FSCACHE_COOKIE_TYPE_INDEX)
cachefiles_attr_changed(&object->fscache);
if (ret < 0) {
printk(KERN_WARNING "CacheFiles: Lookup failed error %d\n",
ret);
fscache_object_lookup_error(&object->fscache);
}
_leave(" [%d]", ret);
}
/*
* indication of lookup completion
*/
static void cachefiles_lookup_complete(struct fscache_object *_object)
{
struct cachefiles_object *object;
object = container_of(_object, struct cachefiles_object, fscache);
_enter("{OBJ%x,%p}", object->fscache.debug_id, object->lookup_data);
if (object->lookup_data) {
kfree(object->lookup_data->key);
kfree(object->lookup_data->auxdata);
kfree(object->lookup_data);
object->lookup_data = NULL;
}
}
/*
* increment the usage count on an inode object (may fail if unmounting)
*/
static
struct fscache_object *cachefiles_grab_object(struct fscache_object *_object)
{
struct cachefiles_object *object =
container_of(_object, struct cachefiles_object, fscache);
_enter("{OBJ%x,%d}", _object->debug_id, atomic_read(&object->usage));
#ifdef CACHEFILES_DEBUG_SLAB
ASSERT((atomic_read(&object->usage) & 0xffff0000) != 0x6b6b0000);
#endif
atomic_inc(&object->usage);
return &object->fscache;
}
/*
* update the auxilliary data for an object object on disk
*/
static void cachefiles_update_object(struct fscache_object *_object)
{
struct cachefiles_object *object;
struct cachefiles_xattr *auxdata;
struct cachefiles_cache *cache;
struct fscache_cookie *cookie;
const struct cred *saved_cred;
unsigned auxlen;
_enter("{OBJ%x}", _object->debug_id);
object = container_of(_object, struct cachefiles_object, fscache);
cache = container_of(object->fscache.cache, struct cachefiles_cache,
cache);
cookie = object->fscache.cookie;
if (!cookie->def->get_aux) {
_leave(" [no aux]");
return;
}
auxdata = kmalloc(2 + 512 + 3, GFP_KERNEL);
if (!auxdata) {
_leave(" [nomem]");
return;
}
auxlen = cookie->def->get_aux(cookie->netfs_data, auxdata->data, 511);
ASSERTCMP(auxlen, <, 511);
auxdata->len = auxlen + 1;
auxdata->type = cookie->def->type;
cachefiles_begin_secure(cache, &saved_cred);
cachefiles_update_object_xattr(object, auxdata);
cachefiles_end_secure(cache, saved_cred);
kfree(auxdata);
_leave("");
}
/*
* discard the resources pinned by an object and effect retirement if
* requested
*/
static void cachefiles_drop_object(struct fscache_object *_object)
{
struct cachefiles_object *object;
struct cachefiles_cache *cache;
const struct cred *saved_cred;
ASSERT(_object);
object = container_of(_object, struct cachefiles_object, fscache);
_enter("{OBJ%x,%d}",
object->fscache.debug_id, atomic_read(&object->usage));
cache = container_of(object->fscache.cache,
struct cachefiles_cache, cache);
#ifdef CACHEFILES_DEBUG_SLAB
ASSERT((atomic_read(&object->usage) & 0xffff0000) != 0x6b6b0000);
#endif
/* delete retired objects */
if (object->fscache.state == FSCACHE_OBJECT_RECYCLING &&
_object != cache->cache.fsdef
) {
_debug("- retire object OBJ%x", object->fscache.debug_id);
cachefiles_begin_secure(cache, &saved_cred);
cachefiles_delete_object(cache, object);
cachefiles_end_secure(cache, saved_cred);
}
/* close the filesystem stuff attached to the object */
if (object->backer != object->dentry)
dput(object->backer);
object->backer = NULL;
/* note that the object is now inactive */
if (test_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags)) {
write_lock(&cache->active_lock);
if (!test_and_clear_bit(CACHEFILES_OBJECT_ACTIVE,
&object->flags))
BUG();
rb_erase(&object->active_node, &cache->active_nodes);
wake_up_bit(&object->flags, CACHEFILES_OBJECT_ACTIVE);
write_unlock(&cache->active_lock);
}
dput(object->dentry);
object->dentry = NULL;
_leave("");
}
/*
* dispose of a reference to an object
*/
static void cachefiles_put_object(struct fscache_object *_object)
{
struct cachefiles_object *object;
struct fscache_cache *cache;
ASSERT(_object);
object = container_of(_object, struct cachefiles_object, fscache);
_enter("{OBJ%x,%d}",
object->fscache.debug_id, atomic_read(&object->usage));
#ifdef CACHEFILES_DEBUG_SLAB
ASSERT((atomic_read(&object->usage) & 0xffff0000) != 0x6b6b0000);
#endif
ASSERTIFCMP(object->fscache.parent,
object->fscache.parent->n_children, >, 0);
if (atomic_dec_and_test(&object->usage)) {
_debug("- kill object OBJ%x", object->fscache.debug_id);
ASSERT(!test_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags));
ASSERTCMP(object->fscache.parent, ==, NULL);
ASSERTCMP(object->backer, ==, NULL);
ASSERTCMP(object->dentry, ==, NULL);
ASSERTCMP(object->fscache.n_ops, ==, 0);
ASSERTCMP(object->fscache.n_children, ==, 0);
if (object->lookup_data) {
kfree(object->lookup_data->key);
kfree(object->lookup_data->auxdata);
kfree(object->lookup_data);
object->lookup_data = NULL;
}
cache = object->fscache.cache;
kmem_cache_free(cachefiles_object_jar, object);
fscache_object_destroyed(cache);
}
_leave("");
}
/*
* sync a cache
*/
static void cachefiles_sync_cache(struct fscache_cache *_cache)
{
struct cachefiles_cache *cache;
const struct cred *saved_cred;
int ret;
_enter("%p", _cache);
cache = container_of(_cache, struct cachefiles_cache, cache);
/* make sure all pages pinned by operations on behalf of the netfs are
* written to disc */
cachefiles_begin_secure(cache, &saved_cred);
ret = fsync_super(cache->mnt->mnt_sb);
cachefiles_end_secure(cache, saved_cred);
if (ret == -EIO)
cachefiles_io_error(cache,
"Attempt to sync backing fs superblock"
" returned error %d",
ret);
}
/*
* notification the attributes on an object have changed
* - called with reads/writes excluded by FS-Cache
*/
static int cachefiles_attr_changed(struct fscache_object *_object)
{
struct cachefiles_object *object;
struct cachefiles_cache *cache;
const struct cred *saved_cred;
struct iattr newattrs;
uint64_t ni_size;
loff_t oi_size;
int ret;
_object->cookie->def->get_attr(_object->cookie->netfs_data, &ni_size);
_enter("{OBJ%x},[%llu]",
_object->debug_id, (unsigned long long) ni_size);
object = container_of(_object, struct cachefiles_object, fscache);
cache = container_of(object->fscache.cache,
struct cachefiles_cache, cache);
if (ni_size == object->i_size)
return 0;
if (!object->backer)
return -ENOBUFS;
ASSERT(S_ISREG(object->backer->d_inode->i_mode));
fscache_set_store_limit(&object->fscache, ni_size);
oi_size = i_size_read(object->backer->d_inode);
if (oi_size == ni_size)
return 0;
newattrs.ia_size = ni_size;
newattrs.ia_valid = ATTR_SIZE;
cachefiles_begin_secure(cache, &saved_cred);
mutex_lock(&object->backer->d_inode->i_mutex);
ret = notify_change(object->backer, &newattrs);
mutex_unlock(&object->backer->d_inode->i_mutex);
cachefiles_end_secure(cache, saved_cred);
if (ret == -EIO) {
fscache_set_store_limit(&object->fscache, 0);
cachefiles_io_error_obj(object, "Size set failed");
ret = -ENOBUFS;
}
_leave(" = %d", ret);
return ret;
}
/*
* dissociate a cache from all the pages it was backing
*/
static void cachefiles_dissociate_pages(struct fscache_cache *cache)
{
_enter("");
}
const struct fscache_cache_ops cachefiles_cache_ops = {
.name = "cachefiles",
.alloc_object = cachefiles_alloc_object,
.lookup_object = cachefiles_lookup_object,
.lookup_complete = cachefiles_lookup_complete,
.grab_object = cachefiles_grab_object,
.update_object = cachefiles_update_object,
.drop_object = cachefiles_drop_object,
.put_object = cachefiles_put_object,
.sync_cache = cachefiles_sync_cache,
.attr_changed = cachefiles_attr_changed,
.read_or_alloc_page = cachefiles_read_or_alloc_page,
.read_or_alloc_pages = cachefiles_read_or_alloc_pages,
.allocate_page = cachefiles_allocate_page,
.allocate_pages = cachefiles_allocate_pages,
.write_page = cachefiles_write_page,
.uncache_page = cachefiles_uncache_page,
.dissociate_pages = cachefiles_dissociate_pages,
};

360
fs/cachefiles/internal.h Normal file
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/* General netfs cache on cache files internal defs
*
* Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public Licence
* as published by the Free Software Foundation; either version
* 2 of the Licence, or (at your option) any later version.
*/
#include <linux/fscache-cache.h>
#include <linux/timer.h>
#include <linux/wait.h>
#include <linux/workqueue.h>
#include <linux/security.h>
struct cachefiles_cache;
struct cachefiles_object;
extern unsigned cachefiles_debug;
#define CACHEFILES_DEBUG_KENTER 1
#define CACHEFILES_DEBUG_KLEAVE 2
#define CACHEFILES_DEBUG_KDEBUG 4
/*
* node records
*/
struct cachefiles_object {
struct fscache_object fscache; /* fscache handle */
struct cachefiles_lookup_data *lookup_data; /* cached lookup data */
struct dentry *dentry; /* the file/dir representing this object */
struct dentry *backer; /* backing file */
loff_t i_size; /* object size */
unsigned long flags;
#define CACHEFILES_OBJECT_ACTIVE 0 /* T if marked active */
atomic_t usage; /* object usage count */
uint8_t type; /* object type */
uint8_t new; /* T if object new */
spinlock_t work_lock;
struct rb_node active_node; /* link in active tree (dentry is key) */
};
extern struct kmem_cache *cachefiles_object_jar;
/*
* Cache files cache definition
*/
struct cachefiles_cache {
struct fscache_cache cache; /* FS-Cache record */
struct vfsmount *mnt; /* mountpoint holding the cache */
struct dentry *graveyard; /* directory into which dead objects go */
struct file *cachefilesd; /* manager daemon handle */
const struct cred *cache_cred; /* security override for accessing cache */
struct mutex daemon_mutex; /* command serialisation mutex */
wait_queue_head_t daemon_pollwq; /* poll waitqueue for daemon */
struct rb_root active_nodes; /* active nodes (can't be culled) */
rwlock_t active_lock; /* lock for active_nodes */
atomic_t gravecounter; /* graveyard uniquifier */
unsigned frun_percent; /* when to stop culling (% files) */
unsigned fcull_percent; /* when to start culling (% files) */
unsigned fstop_percent; /* when to stop allocating (% files) */
unsigned brun_percent; /* when to stop culling (% blocks) */
unsigned bcull_percent; /* when to start culling (% blocks) */
unsigned bstop_percent; /* when to stop allocating (% blocks) */
unsigned bsize; /* cache's block size */
unsigned bshift; /* min(ilog2(PAGE_SIZE / bsize), 0) */
uint64_t frun; /* when to stop culling */
uint64_t fcull; /* when to start culling */
uint64_t fstop; /* when to stop allocating */
sector_t brun; /* when to stop culling */
sector_t bcull; /* when to start culling */
sector_t bstop; /* when to stop allocating */
unsigned long flags;
#define CACHEFILES_READY 0 /* T if cache prepared */
#define CACHEFILES_DEAD 1 /* T if cache dead */
#define CACHEFILES_CULLING 2 /* T if cull engaged */
#define CACHEFILES_STATE_CHANGED 3 /* T if state changed (poll trigger) */
char *rootdirname; /* name of cache root directory */
char *secctx; /* LSM security context */
char *tag; /* cache binding tag */
};
/*
* backing file read tracking
*/
struct cachefiles_one_read {
wait_queue_t monitor; /* link into monitored waitqueue */
struct page *back_page; /* backing file page we're waiting for */
struct page *netfs_page; /* netfs page we're going to fill */
struct fscache_retrieval *op; /* retrieval op covering this */
struct list_head op_link; /* link in op's todo list */
};
/*
* backing file write tracking
*/
struct cachefiles_one_write {
struct page *netfs_page; /* netfs page to copy */
struct cachefiles_object *object;
struct list_head obj_link; /* link in object's lists */
fscache_rw_complete_t end_io_func;
void *context;
};
/*
* auxiliary data xattr buffer
*/
struct cachefiles_xattr {
uint16_t len;
uint8_t type;
uint8_t data[];
};
/*
* note change of state for daemon
*/
static inline void cachefiles_state_changed(struct cachefiles_cache *cache)
{
set_bit(CACHEFILES_STATE_CHANGED, &cache->flags);
wake_up_all(&cache->daemon_pollwq);
}
/*
* cf-bind.c
*/
extern int cachefiles_daemon_bind(struct cachefiles_cache *cache, char *args);
extern void cachefiles_daemon_unbind(struct cachefiles_cache *cache);
/*
* cf-daemon.c
*/
extern const struct file_operations cachefiles_daemon_fops;
extern int cachefiles_has_space(struct cachefiles_cache *cache,
unsigned fnr, unsigned bnr);
/*
* cf-interface.c
*/
extern const struct fscache_cache_ops cachefiles_cache_ops;
/*
* cf-key.c
*/
extern char *cachefiles_cook_key(const u8 *raw, int keylen, uint8_t type);
/*
* cf-namei.c
*/
extern int cachefiles_delete_object(struct cachefiles_cache *cache,
struct cachefiles_object *object);
extern int cachefiles_walk_to_object(struct cachefiles_object *parent,
struct cachefiles_object *object,
const char *key,
struct cachefiles_xattr *auxdata);
extern struct dentry *cachefiles_get_directory(struct cachefiles_cache *cache,
struct dentry *dir,
const char *name);
extern int cachefiles_cull(struct cachefiles_cache *cache, struct dentry *dir,
char *filename);
extern int cachefiles_check_in_use(struct cachefiles_cache *cache,
struct dentry *dir, char *filename);
/*
* cf-proc.c
*/
#ifdef CONFIG_CACHEFILES_HISTOGRAM
extern atomic_t cachefiles_lookup_histogram[HZ];
extern atomic_t cachefiles_mkdir_histogram[HZ];
extern atomic_t cachefiles_create_histogram[HZ];
extern int __init cachefiles_proc_init(void);
extern void cachefiles_proc_cleanup(void);
static inline
void cachefiles_hist(atomic_t histogram[], unsigned long start_jif)
{
unsigned long jif = jiffies - start_jif;
if (jif >= HZ)
jif = HZ - 1;
atomic_inc(&histogram[jif]);
}
#else
#define cachefiles_proc_init() (0)
#define cachefiles_proc_cleanup() do {} while (0)
#define cachefiles_hist(hist, start_jif) do {} while (0)
#endif
/*
* cf-rdwr.c
*/
extern int cachefiles_read_or_alloc_page(struct fscache_retrieval *,
struct page *, gfp_t);
extern int cachefiles_read_or_alloc_pages(struct fscache_retrieval *,
struct list_head *, unsigned *,
gfp_t);
extern int cachefiles_allocate_page(struct fscache_retrieval *, struct page *,
gfp_t);
extern int cachefiles_allocate_pages(struct fscache_retrieval *,
struct list_head *, unsigned *, gfp_t);
extern int cachefiles_write_page(struct fscache_storage *, struct page *);
extern void cachefiles_uncache_page(struct fscache_object *, struct page *);
/*
* cf-security.c
*/
extern int cachefiles_get_security_ID(struct cachefiles_cache *cache);
extern int cachefiles_determine_cache_security(struct cachefiles_cache *cache,
struct dentry *root,
const struct cred **_saved_cred);
static inline void cachefiles_begin_secure(struct cachefiles_cache *cache,
const struct cred **_saved_cred)
{
*_saved_cred = override_creds(cache->cache_cred);
}
static inline void cachefiles_end_secure(struct cachefiles_cache *cache,
const struct cred *saved_cred)
{
revert_creds(saved_cred);
}
/*
* cf-xattr.c
*/
extern int cachefiles_check_object_type(struct cachefiles_object *object);
extern int cachefiles_set_object_xattr(struct cachefiles_object *object,
struct cachefiles_xattr *auxdata);
extern int cachefiles_update_object_xattr(struct cachefiles_object *object,
struct cachefiles_xattr *auxdata);
extern int cachefiles_check_object_xattr(struct cachefiles_object *object,
struct cachefiles_xattr *auxdata);
extern int cachefiles_remove_object_xattr(struct cachefiles_cache *cache,
struct dentry *dentry);
/*
* error handling
*/
#define kerror(FMT, ...) printk(KERN_ERR "CacheFiles: "FMT"\n", ##__VA_ARGS__)
#define cachefiles_io_error(___cache, FMT, ...) \
do { \
kerror("I/O Error: " FMT, ##__VA_ARGS__); \
fscache_io_error(&(___cache)->cache); \
set_bit(CACHEFILES_DEAD, &(___cache)->flags); \
} while (0)
#define cachefiles_io_error_obj(object, FMT, ...) \
do { \
struct cachefiles_cache *___cache; \
\
___cache = container_of((object)->fscache.cache, \
struct cachefiles_cache, cache); \
cachefiles_io_error(___cache, FMT, ##__VA_ARGS__); \
} while (0)
/*
* debug tracing
*/
#define dbgprintk(FMT, ...) \
printk(KERN_DEBUG "[%-6.6s] "FMT"\n", current->comm, ##__VA_ARGS__)
/* make sure we maintain the format strings, even when debugging is disabled */
static inline void _dbprintk(const char *fmt, ...)
__attribute__((format(printf, 1, 2)));
static inline void _dbprintk(const char *fmt, ...)
{
}
#define kenter(FMT, ...) dbgprintk("==> %s("FMT")", __func__, ##__VA_ARGS__)
#define kleave(FMT, ...) dbgprintk("<== %s()"FMT"", __func__, ##__VA_ARGS__)
#define kdebug(FMT, ...) dbgprintk(FMT, ##__VA_ARGS__)
#if defined(__KDEBUG)
#define _enter(FMT, ...) kenter(FMT, ##__VA_ARGS__)
#define _leave(FMT, ...) kleave(FMT, ##__VA_ARGS__)
#define _debug(FMT, ...) kdebug(FMT, ##__VA_ARGS__)
#elif defined(CONFIG_CACHEFILES_DEBUG)
#define _enter(FMT, ...) \
do { \
if (cachefiles_debug & CACHEFILES_DEBUG_KENTER) \
kenter(FMT, ##__VA_ARGS__); \
} while (0)
#define _leave(FMT, ...) \
do { \
if (cachefiles_debug & CACHEFILES_DEBUG_KLEAVE) \
kleave(FMT, ##__VA_ARGS__); \
} while (0)
#define _debug(FMT, ...) \
do { \
if (cachefiles_debug & CACHEFILES_DEBUG_KDEBUG) \
kdebug(FMT, ##__VA_ARGS__); \
} while (0)
#else
#define _enter(FMT, ...) _dbprintk("==> %s("FMT")", __func__, ##__VA_ARGS__)
#define _leave(FMT, ...) _dbprintk("<== %s()"FMT"", __func__, ##__VA_ARGS__)
#define _debug(FMT, ...) _dbprintk(FMT, ##__VA_ARGS__)
#endif
#if 1 /* defined(__KDEBUGALL) */
#define ASSERT(X) \
do { \
if (unlikely(!(X))) { \
printk(KERN_ERR "\n"); \
printk(KERN_ERR "CacheFiles: Assertion failed\n"); \
BUG(); \
} \
} while (0)
#define ASSERTCMP(X, OP, Y) \
do { \
if (unlikely(!((X) OP (Y)))) { \
printk(KERN_ERR "\n"); \
printk(KERN_ERR "CacheFiles: Assertion failed\n"); \
printk(KERN_ERR "%lx " #OP " %lx is false\n", \
(unsigned long)(X), (unsigned long)(Y)); \
BUG(); \
} \
} while (0)
#define ASSERTIF(C, X) \
do { \
if (unlikely((C) && !(X))) { \
printk(KERN_ERR "\n"); \
printk(KERN_ERR "CacheFiles: Assertion failed\n"); \
BUG(); \
} \
} while (0)
#define ASSERTIFCMP(C, X, OP, Y) \
do { \
if (unlikely((C) && !((X) OP (Y)))) { \
printk(KERN_ERR "\n"); \
printk(KERN_ERR "CacheFiles: Assertion failed\n"); \
printk(KERN_ERR "%lx " #OP " %lx is false\n", \
(unsigned long)(X), (unsigned long)(Y)); \
BUG(); \
} \
} while (0)
#else
#define ASSERT(X) do {} while (0)
#define ASSERTCMP(X, OP, Y) do {} while (0)
#define ASSERTIF(C, X) do {} while (0)
#define ASSERTIFCMP(C, X, OP, Y) do {} while (0)
#endif

159
fs/cachefiles/key.c Normal file
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/* Key to pathname encoder
*
* Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public Licence
* as published by the Free Software Foundation; either version
* 2 of the Licence, or (at your option) any later version.
*/
#include <linux/slab.h>
#include "internal.h"
static const char cachefiles_charmap[64] =
"0123456789" /* 0 - 9 */
"abcdefghijklmnopqrstuvwxyz" /* 10 - 35 */
"ABCDEFGHIJKLMNOPQRSTUVWXYZ" /* 36 - 61 */
"_-" /* 62 - 63 */
;
static const char cachefiles_filecharmap[256] = {
/* we skip space and tab and control chars */
[33 ... 46] = 1, /* '!' -> '.' */
/* we skip '/' as it's significant to pathwalk */
[48 ... 127] = 1, /* '0' -> '~' */
};
/*
* turn the raw key into something cooked
* - the raw key should include the length in the two bytes at the front
* - the key may be up to 514 bytes in length (including the length word)
* - "base64" encode the strange keys, mapping 3 bytes of raw to four of
* cooked
* - need to cut the cooked key into 252 char lengths (189 raw bytes)
*/
char *cachefiles_cook_key(const u8 *raw, int keylen, uint8_t type)
{
unsigned char csum, ch;
unsigned int acc;
char *key;
int loop, len, max, seg, mark, print;
_enter(",%d", keylen);
BUG_ON(keylen < 2 || keylen > 514);
csum = raw[0] + raw[1];
print = 1;
for (loop = 2; loop < keylen; loop++) {
ch = raw[loop];
csum += ch;
print &= cachefiles_filecharmap[ch];
}
if (print) {
/* if the path is usable ASCII, then we render it directly */
max = keylen - 2;
max += 2; /* two base64'd length chars on the front */
max += 5; /* @checksum/M */
max += 3 * 2; /* maximum number of segment dividers (".../M")
* is ((514 + 251) / 252) = 3
*/
max += 1; /* NUL on end */
} else {
/* calculate the maximum length of the cooked key */
keylen = (keylen + 2) / 3;
max = keylen * 4;
max += 5; /* @checksum/M */
max += 3 * 2; /* maximum number of segment dividers (".../M")
* is ((514 + 188) / 189) = 3
*/
max += 1; /* NUL on end */
}
max += 1; /* 2nd NUL on end */
_debug("max: %d", max);
key = kmalloc(max, GFP_KERNEL);
if (!key)
return NULL;
len = 0;
/* build the cooked key */
sprintf(key, "@%02x%c+", (unsigned) csum, 0);
len = 5;
mark = len - 1;
if (print) {
acc = *(uint16_t *) raw;
raw += 2;
key[len + 1] = cachefiles_charmap[acc & 63];
acc >>= 6;
key[len] = cachefiles_charmap[acc & 63];
len += 2;
seg = 250;
for (loop = keylen; loop > 0; loop--) {
if (seg <= 0) {
key[len++] = '\0';
mark = len;
key[len++] = '+';
seg = 252;
}
key[len++] = *raw++;
ASSERT(len < max);
}
switch (type) {
case FSCACHE_COOKIE_TYPE_INDEX: type = 'I'; break;
case FSCACHE_COOKIE_TYPE_DATAFILE: type = 'D'; break;
default: type = 'S'; break;
}
} else {
seg = 252;
for (loop = keylen; loop > 0; loop--) {
if (seg <= 0) {
key[len++] = '\0';
mark = len;
key[len++] = '+';
seg = 252;
}
acc = *raw++;
acc |= *raw++ << 8;
acc |= *raw++ << 16;
_debug("acc: %06x", acc);
key[len++] = cachefiles_charmap[acc & 63];
acc >>= 6;
key[len++] = cachefiles_charmap[acc & 63];
acc >>= 6;
key[len++] = cachefiles_charmap[acc & 63];
acc >>= 6;
key[len++] = cachefiles_charmap[acc & 63];
ASSERT(len < max);
}
switch (type) {
case FSCACHE_COOKIE_TYPE_INDEX: type = 'J'; break;
case FSCACHE_COOKIE_TYPE_DATAFILE: type = 'E'; break;
default: type = 'T'; break;
}
}
key[mark] = type;
key[len++] = 0;
key[len] = 0;
_leave(" = %p %d", key, len);
return key;
}

106
fs/cachefiles/main.c Normal file
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@ -0,0 +1,106 @@
/* Network filesystem caching backend to use cache files on a premounted
* filesystem
*
* Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public Licence
* as published by the Free Software Foundation; either version
* 2 of the Licence, or (at your option) any later version.
*/
#include <linux/module.h>
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/completion.h>
#include <linux/slab.h>
#include <linux/fs.h>
#include <linux/file.h>
#include <linux/namei.h>
#include <linux/mount.h>
#include <linux/statfs.h>
#include <linux/sysctl.h>
#include <linux/miscdevice.h>
#include "internal.h"
unsigned cachefiles_debug;
module_param_named(debug, cachefiles_debug, uint, S_IWUSR | S_IRUGO);
MODULE_PARM_DESC(cachefiles_debug, "CacheFiles debugging mask");
MODULE_DESCRIPTION("Mounted-filesystem based cache");
MODULE_AUTHOR("Red Hat, Inc.");
MODULE_LICENSE("GPL");
struct kmem_cache *cachefiles_object_jar;
static struct miscdevice cachefiles_dev = {
.minor = MISC_DYNAMIC_MINOR,
.name = "cachefiles",
.fops = &cachefiles_daemon_fops,
};
static void cachefiles_object_init_once(void *_object)
{
struct cachefiles_object *object = _object;
memset(object, 0, sizeof(*object));
spin_lock_init(&object->work_lock);
}
/*
* initialise the fs caching module
*/
static int __init cachefiles_init(void)
{
int ret;
ret = misc_register(&cachefiles_dev);
if (ret < 0)
goto error_dev;
/* create an object jar */
ret = -ENOMEM;
cachefiles_object_jar =
kmem_cache_create("cachefiles_object_jar",
sizeof(struct cachefiles_object),
0,
SLAB_HWCACHE_ALIGN,
cachefiles_object_init_once);
if (!cachefiles_object_jar) {
printk(KERN_NOTICE
"CacheFiles: Failed to allocate an object jar\n");
goto error_object_jar;
}
ret = cachefiles_proc_init();
if (ret < 0)
goto error_proc;
printk(KERN_INFO "CacheFiles: Loaded\n");
return 0;
error_proc:
kmem_cache_destroy(cachefiles_object_jar);
error_object_jar:
misc_deregister(&cachefiles_dev);
error_dev:
kerror("failed to register: %d", ret);
return ret;
}
fs_initcall(cachefiles_init);
/*
* clean up on module removal
*/
static void __exit cachefiles_exit(void)
{
printk(KERN_INFO "CacheFiles: Unloading\n");
cachefiles_proc_cleanup();
kmem_cache_destroy(cachefiles_object_jar);
misc_deregister(&cachefiles_dev);
}
module_exit(cachefiles_exit);

771
fs/cachefiles/namei.c Normal file
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@ -0,0 +1,771 @@
/* CacheFiles path walking and related routines
*
* Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public Licence
* as published by the Free Software Foundation; either version
* 2 of the Licence, or (at your option) any later version.
*/
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/file.h>
#include <linux/fs.h>
#include <linux/fsnotify.h>
#include <linux/quotaops.h>
#include <linux/xattr.h>
#include <linux/mount.h>
#include <linux/namei.h>
#include <linux/security.h>
#include "internal.h"
static int cachefiles_wait_bit(void *flags)
{
schedule();
return 0;
}
/*
* record the fact that an object is now active
*/
static void cachefiles_mark_object_active(struct cachefiles_cache *cache,
struct cachefiles_object *object)
{
struct cachefiles_object *xobject;
struct rb_node **_p, *_parent = NULL;
struct dentry *dentry;
_enter(",%p", object);
try_again:
write_lock(&cache->active_lock);
if (test_and_set_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags))
BUG();
dentry = object->dentry;
_p = &cache->active_nodes.rb_node;
while (*_p) {
_parent = *_p;
xobject = rb_entry(_parent,
struct cachefiles_object, active_node);
ASSERT(xobject != object);
if (xobject->dentry > dentry)
_p = &(*_p)->rb_left;
else if (xobject->dentry < dentry)
_p = &(*_p)->rb_right;
else
goto wait_for_old_object;
}
rb_link_node(&object->active_node, _parent, _p);
rb_insert_color(&object->active_node, &cache->active_nodes);
write_unlock(&cache->active_lock);
_leave("");
return;
/* an old object from a previous incarnation is hogging the slot - we
* need to wait for it to be destroyed */
wait_for_old_object:
if (xobject->fscache.state < FSCACHE_OBJECT_DYING) {
printk(KERN_ERR "\n");
printk(KERN_ERR "CacheFiles: Error:"
" Unexpected object collision\n");
printk(KERN_ERR "xobject: OBJ%x\n",
xobject->fscache.debug_id);
printk(KERN_ERR "xobjstate=%s\n",
fscache_object_states[xobject->fscache.state]);
printk(KERN_ERR "xobjflags=%lx\n", xobject->fscache.flags);
printk(KERN_ERR "xobjevent=%lx [%lx]\n",
xobject->fscache.events, xobject->fscache.event_mask);
printk(KERN_ERR "xops=%u inp=%u exc=%u\n",
xobject->fscache.n_ops, xobject->fscache.n_in_progress,
xobject->fscache.n_exclusive);
printk(KERN_ERR "xcookie=%p [pr=%p nd=%p fl=%lx]\n",
xobject->fscache.cookie,
xobject->fscache.cookie->parent,
xobject->fscache.cookie->netfs_data,
xobject->fscache.cookie->flags);
printk(KERN_ERR "xparent=%p\n",
xobject->fscache.parent);
printk(KERN_ERR "object: OBJ%x\n",
object->fscache.debug_id);
printk(KERN_ERR "cookie=%p [pr=%p nd=%p fl=%lx]\n",
object->fscache.cookie,
object->fscache.cookie->parent,
object->fscache.cookie->netfs_data,
object->fscache.cookie->flags);
printk(KERN_ERR "parent=%p\n",
object->fscache.parent);
BUG();
}
atomic_inc(&xobject->usage);
write_unlock(&cache->active_lock);
_debug(">>> wait");
wait_on_bit(&xobject->flags, CACHEFILES_OBJECT_ACTIVE,
cachefiles_wait_bit, TASK_UNINTERRUPTIBLE);
_debug("<<< waited");
cache->cache.ops->put_object(&xobject->fscache);
goto try_again;
}
/*
* delete an object representation from the cache
* - file backed objects are unlinked
* - directory backed objects are stuffed into the graveyard for userspace to
* delete
* - unlocks the directory mutex
*/
static int cachefiles_bury_object(struct cachefiles_cache *cache,
struct dentry *dir,
struct dentry *rep)
{
struct dentry *grave, *trap;
char nbuffer[8 + 8 + 1];
int ret;
_enter(",'%*.*s','%*.*s'",
dir->d_name.len, dir->d_name.len, dir->d_name.name,
rep->d_name.len, rep->d_name.len, rep->d_name.name);
/* non-directories can just be unlinked */
if (!S_ISDIR(rep->d_inode->i_mode)) {
_debug("unlink stale object");
ret = vfs_unlink(dir->d_inode, rep);
mutex_unlock(&dir->d_inode->i_mutex);
if (ret == -EIO)
cachefiles_io_error(cache, "Unlink failed");
_leave(" = %d", ret);
return ret;
}
/* directories have to be moved to the graveyard */
_debug("move stale object to graveyard");
mutex_unlock(&dir->d_inode->i_mutex);
try_again:
/* first step is to make up a grave dentry in the graveyard */
sprintf(nbuffer, "%08x%08x",
(uint32_t) get_seconds(),
(uint32_t) atomic_inc_return(&cache->gravecounter));
/* do the multiway lock magic */
trap = lock_rename(cache->graveyard, dir);
/* do some checks before getting the grave dentry */
if (rep->d_parent != dir) {
/* the entry was probably culled when we dropped the parent dir
* lock */
unlock_rename(cache->graveyard, dir);
_leave(" = 0 [culled?]");
return 0;
}
if (!S_ISDIR(cache->graveyard->d_inode->i_mode)) {
unlock_rename(cache->graveyard, dir);
cachefiles_io_error(cache, "Graveyard no longer a directory");
return -EIO;
}
if (trap == rep) {
unlock_rename(cache->graveyard, dir);
cachefiles_io_error(cache, "May not make directory loop");
return -EIO;
}
if (d_mountpoint(rep)) {
unlock_rename(cache->graveyard, dir);
cachefiles_io_error(cache, "Mountpoint in cache");
return -EIO;
}
grave = lookup_one_len(nbuffer, cache->graveyard, strlen(nbuffer));
if (IS_ERR(grave)) {
unlock_rename(cache->graveyard, dir);
if (PTR_ERR(grave) == -ENOMEM) {
_leave(" = -ENOMEM");
return -ENOMEM;
}
cachefiles_io_error(cache, "Lookup error %ld",
PTR_ERR(grave));
return -EIO;
}
if (grave->d_inode) {
unlock_rename(cache->graveyard, dir);
dput(grave);
grave = NULL;
cond_resched();
goto try_again;
}
if (d_mountpoint(grave)) {
unlock_rename(cache->graveyard, dir);
dput(grave);
cachefiles_io_error(cache, "Mountpoint in graveyard");
return -EIO;
}
/* target should not be an ancestor of source */
if (trap == grave) {
unlock_rename(cache->graveyard, dir);
dput(grave);
cachefiles_io_error(cache, "May not make directory loop");
return -EIO;
}
/* attempt the rename */
ret = vfs_rename(dir->d_inode, rep, cache->graveyard->d_inode, grave);
if (ret != 0 && ret != -ENOMEM)
cachefiles_io_error(cache, "Rename failed with error %d", ret);
unlock_rename(cache->graveyard, dir);
dput(grave);
_leave(" = 0");
return 0;
}
/*
* delete an object representation from the cache
*/
int cachefiles_delete_object(struct cachefiles_cache *cache,
struct cachefiles_object *object)
{
struct dentry *dir;
int ret;
_enter(",{%p}", object->dentry);
ASSERT(object->dentry);
ASSERT(object->dentry->d_inode);
ASSERT(object->dentry->d_parent);
dir = dget_parent(object->dentry);
mutex_lock(&dir->d_inode->i_mutex);
ret = cachefiles_bury_object(cache, dir, object->dentry);
dput(dir);
_leave(" = %d", ret);
return ret;
}
/*
* walk from the parent object to the child object through the backing
* filesystem, creating directories as we go
*/
int cachefiles_walk_to_object(struct cachefiles_object *parent,
struct cachefiles_object *object,
const char *key,
struct cachefiles_xattr *auxdata)
{
struct cachefiles_cache *cache;
struct dentry *dir, *next = NULL;
unsigned long start;
const char *name;
int ret, nlen;
_enter("{%p},,%s,", parent->dentry, key);
cache = container_of(parent->fscache.cache,
struct cachefiles_cache, cache);
ASSERT(parent->dentry);
ASSERT(parent->dentry->d_inode);
if (!(S_ISDIR(parent->dentry->d_inode->i_mode))) {
// TODO: convert file to dir
_leave("looking up in none directory");
return -ENOBUFS;
}
dir = dget(parent->dentry);
advance:
/* attempt to transit the first directory component */
name = key;
nlen = strlen(key);
/* key ends in a double NUL */
key = key + nlen + 1;
if (!*key)
key = NULL;
lookup_again:
/* search the current directory for the element name */
_debug("lookup '%s'", name);
mutex_lock(&dir->d_inode->i_mutex);
start = jiffies;
next = lookup_one_len(name, dir, nlen);
cachefiles_hist(cachefiles_lookup_histogram, start);
if (IS_ERR(next))
goto lookup_error;
_debug("next -> %p %s", next, next->d_inode ? "positive" : "negative");
if (!key)
object->new = !next->d_inode;
/* if this element of the path doesn't exist, then the lookup phase
* failed, and we can release any readers in the certain knowledge that
* there's nothing for them to actually read */
if (!next->d_inode)
fscache_object_lookup_negative(&object->fscache);
/* we need to create the object if it's negative */
if (key || object->type == FSCACHE_COOKIE_TYPE_INDEX) {
/* index objects and intervening tree levels must be subdirs */
if (!next->d_inode) {
ret = cachefiles_has_space(cache, 1, 0);
if (ret < 0)
goto create_error;
start = jiffies;
ret = vfs_mkdir(dir->d_inode, next, 0);
cachefiles_hist(cachefiles_mkdir_histogram, start);
if (ret < 0)
goto create_error;
ASSERT(next->d_inode);
_debug("mkdir -> %p{%p{ino=%lu}}",
next, next->d_inode, next->d_inode->i_ino);
} else if (!S_ISDIR(next->d_inode->i_mode)) {
kerror("inode %lu is not a directory",
next->d_inode->i_ino);
ret = -ENOBUFS;
goto error;
}
} else {
/* non-index objects start out life as files */
if (!next->d_inode) {
ret = cachefiles_has_space(cache, 1, 0);
if (ret < 0)
goto create_error;
start = jiffies;
ret = vfs_create(dir->d_inode, next, S_IFREG, NULL);
cachefiles_hist(cachefiles_create_histogram, start);
if (ret < 0)
goto create_error;
ASSERT(next->d_inode);
_debug("create -> %p{%p{ino=%lu}}",
next, next->d_inode, next->d_inode->i_ino);
} else if (!S_ISDIR(next->d_inode->i_mode) &&
!S_ISREG(next->d_inode->i_mode)
) {
kerror("inode %lu is not a file or directory",
next->d_inode->i_ino);
ret = -ENOBUFS;
goto error;
}
}
/* process the next component */
if (key) {
_debug("advance");
mutex_unlock(&dir->d_inode->i_mutex);
dput(dir);
dir = next;
next = NULL;
goto advance;
}
/* we've found the object we were looking for */
object->dentry = next;
/* if we've found that the terminal object exists, then we need to
* check its attributes and delete it if it's out of date */
if (!object->new) {
_debug("validate '%*.*s'",
next->d_name.len, next->d_name.len, next->d_name.name);
ret = cachefiles_check_object_xattr(object, auxdata);
if (ret == -ESTALE) {
/* delete the object (the deleter drops the directory
* mutex) */
object->dentry = NULL;
ret = cachefiles_bury_object(cache, dir, next);
dput(next);
next = NULL;
if (ret < 0)
goto delete_error;
_debug("redo lookup");
goto lookup_again;
}
}
/* note that we're now using this object */
cachefiles_mark_object_active(cache, object);
mutex_unlock(&dir->d_inode->i_mutex);
dput(dir);
dir = NULL;
_debug("=== OBTAINED_OBJECT ===");
if (object->new) {
/* attach data to a newly constructed terminal object */
ret = cachefiles_set_object_xattr(object, auxdata);
if (ret < 0)
goto check_error;
} else {
/* always update the atime on an object we've just looked up
* (this is used to keep track of culling, and atimes are only
* updated by read, write and readdir but not lookup or
* open) */
touch_atime(cache->mnt, next);
}
/* open a file interface onto a data file */
if (object->type != FSCACHE_COOKIE_TYPE_INDEX) {
if (S_ISREG(object->dentry->d_inode->i_mode)) {
const struct address_space_operations *aops;
ret = -EPERM;
aops = object->dentry->d_inode->i_mapping->a_ops;
if (!aops->bmap)
goto check_error;
object->backer = object->dentry;
} else {
BUG(); // TODO: open file in data-class subdir
}
}
object->new = 0;
fscache_obtained_object(&object->fscache);
_leave(" = 0 [%lu]", object->dentry->d_inode->i_ino);
return 0;
create_error:
_debug("create error %d", ret);
if (ret == -EIO)
cachefiles_io_error(cache, "Create/mkdir failed");
goto error;
check_error:
_debug("check error %d", ret);
write_lock(&cache->active_lock);
rb_erase(&object->active_node, &cache->active_nodes);
clear_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags);
wake_up_bit(&object->flags, CACHEFILES_OBJECT_ACTIVE);
write_unlock(&cache->active_lock);
dput(object->dentry);
object->dentry = NULL;
goto error_out;
delete_error:
_debug("delete error %d", ret);
goto error_out2;
lookup_error:
_debug("lookup error %ld", PTR_ERR(next));
ret = PTR_ERR(next);
if (ret == -EIO)
cachefiles_io_error(cache, "Lookup failed");
next = NULL;
error:
mutex_unlock(&dir->d_inode->i_mutex);
dput(next);
error_out2:
dput(dir);
error_out:
if (ret == -ENOSPC)
ret = -ENOBUFS;
_leave(" = error %d", -ret);
return ret;
}
/*
* get a subdirectory
*/
struct dentry *cachefiles_get_directory(struct cachefiles_cache *cache,
struct dentry *dir,
const char *dirname)
{
struct dentry *subdir;
unsigned long start;
int ret;
_enter(",,%s", dirname);
/* search the current directory for the element name */
mutex_lock(&dir->d_inode->i_mutex);
start = jiffies;
subdir = lookup_one_len(dirname, dir, strlen(dirname));
cachefiles_hist(cachefiles_lookup_histogram, start);
if (IS_ERR(subdir)) {
if (PTR_ERR(subdir) == -ENOMEM)
goto nomem_d_alloc;
goto lookup_error;
}
_debug("subdir -> %p %s",
subdir, subdir->d_inode ? "positive" : "negative");
/* we need to create the subdir if it doesn't exist yet */
if (!subdir->d_inode) {
ret = cachefiles_has_space(cache, 1, 0);
if (ret < 0)
goto mkdir_error;
_debug("attempt mkdir");
ret = vfs_mkdir(dir->d_inode, subdir, 0700);
if (ret < 0)
goto mkdir_error;
ASSERT(subdir->d_inode);
_debug("mkdir -> %p{%p{ino=%lu}}",
subdir,
subdir->d_inode,
subdir->d_inode->i_ino);
}
mutex_unlock(&dir->d_inode->i_mutex);
/* we need to make sure the subdir is a directory */
ASSERT(subdir->d_inode);
if (!S_ISDIR(subdir->d_inode->i_mode)) {
kerror("%s is not a directory", dirname);
ret = -EIO;
goto check_error;
}
ret = -EPERM;
if (!subdir->d_inode->i_op ||
!subdir->d_inode->i_op->setxattr ||
!subdir->d_inode->i_op->getxattr ||
!subdir->d_inode->i_op->lookup ||
!subdir->d_inode->i_op->mkdir ||
!subdir->d_inode->i_op->create ||
!subdir->d_inode->i_op->rename ||
!subdir->d_inode->i_op->rmdir ||
!subdir->d_inode->i_op->unlink)
goto check_error;
_leave(" = [%lu]", subdir->d_inode->i_ino);
return subdir;
check_error:
dput(subdir);
_leave(" = %d [check]", ret);
return ERR_PTR(ret);
mkdir_error:
mutex_unlock(&dir->d_inode->i_mutex);
dput(subdir);
kerror("mkdir %s failed with error %d", dirname, ret);
return ERR_PTR(ret);
lookup_error:
mutex_unlock(&dir->d_inode->i_mutex);
ret = PTR_ERR(subdir);
kerror("Lookup %s failed with error %d", dirname, ret);
return ERR_PTR(ret);
nomem_d_alloc:
mutex_unlock(&dir->d_inode->i_mutex);
_leave(" = -ENOMEM");
return ERR_PTR(-ENOMEM);
}
/*
* find out if an object is in use or not
* - if finds object and it's not in use:
* - returns a pointer to the object and a reference on it
* - returns with the directory locked
*/
static struct dentry *cachefiles_check_active(struct cachefiles_cache *cache,
struct dentry *dir,
char *filename)
{
struct cachefiles_object *object;
struct rb_node *_n;
struct dentry *victim;
unsigned long start;
int ret;
//_enter(",%*.*s/,%s",
// dir->d_name.len, dir->d_name.len, dir->d_name.name, filename);
/* look up the victim */
mutex_lock_nested(&dir->d_inode->i_mutex, 1);
start = jiffies;
victim = lookup_one_len(filename, dir, strlen(filename));
cachefiles_hist(cachefiles_lookup_histogram, start);
if (IS_ERR(victim))
goto lookup_error;
//_debug("victim -> %p %s",
// victim, victim->d_inode ? "positive" : "negative");
/* if the object is no longer there then we probably retired the object
* at the netfs's request whilst the cull was in progress
*/
if (!victim->d_inode) {
mutex_unlock(&dir->d_inode->i_mutex);
dput(victim);
_leave(" = -ENOENT [absent]");
return ERR_PTR(-ENOENT);
}
/* check to see if we're using this object */
read_lock(&cache->active_lock);
_n = cache->active_nodes.rb_node;
while (_n) {
object = rb_entry(_n, struct cachefiles_object, active_node);
if (object->dentry > victim)
_n = _n->rb_left;
else if (object->dentry < victim)
_n = _n->rb_right;
else
goto object_in_use;
}
read_unlock(&cache->active_lock);
//_leave(" = %p", victim);
return victim;
object_in_use:
read_unlock(&cache->active_lock);
mutex_unlock(&dir->d_inode->i_mutex);
dput(victim);
//_leave(" = -EBUSY [in use]");
return ERR_PTR(-EBUSY);
lookup_error:
mutex_unlock(&dir->d_inode->i_mutex);
ret = PTR_ERR(victim);
if (ret == -ENOENT) {
/* file or dir now absent - probably retired by netfs */
_leave(" = -ESTALE [absent]");
return ERR_PTR(-ESTALE);
}
if (ret == -EIO) {
cachefiles_io_error(cache, "Lookup failed");
} else if (ret != -ENOMEM) {
kerror("Internal error: %d", ret);
ret = -EIO;
}
_leave(" = %d", ret);
return ERR_PTR(ret);
}
/*
* cull an object if it's not in use
* - called only by cache manager daemon
*/
int cachefiles_cull(struct cachefiles_cache *cache, struct dentry *dir,
char *filename)
{
struct dentry *victim;
int ret;
_enter(",%*.*s/,%s",
dir->d_name.len, dir->d_name.len, dir->d_name.name, filename);
victim = cachefiles_check_active(cache, dir, filename);
if (IS_ERR(victim))
return PTR_ERR(victim);
_debug("victim -> %p %s",
victim, victim->d_inode ? "positive" : "negative");
/* okay... the victim is not being used so we can cull it
* - start by marking it as stale
*/
_debug("victim is cullable");
ret = cachefiles_remove_object_xattr(cache, victim);
if (ret < 0)
goto error_unlock;
/* actually remove the victim (drops the dir mutex) */
_debug("bury");
ret = cachefiles_bury_object(cache, dir, victim);
if (ret < 0)
goto error;
dput(victim);
_leave(" = 0");
return 0;
error_unlock:
mutex_unlock(&dir->d_inode->i_mutex);
error:
dput(victim);
if (ret == -ENOENT) {
/* file or dir now absent - probably retired by netfs */
_leave(" = -ESTALE [absent]");
return -ESTALE;
}
if (ret != -ENOMEM) {
kerror("Internal error: %d", ret);
ret = -EIO;
}
_leave(" = %d", ret);
return ret;
}
/*
* find out if an object is in use or not
* - called only by cache manager daemon
* - returns -EBUSY or 0 to indicate whether an object is in use or not
*/
int cachefiles_check_in_use(struct cachefiles_cache *cache, struct dentry *dir,
char *filename)
{
struct dentry *victim;
//_enter(",%*.*s/,%s",
// dir->d_name.len, dir->d_name.len, dir->d_name.name, filename);
victim = cachefiles_check_active(cache, dir, filename);
if (IS_ERR(victim))
return PTR_ERR(victim);
mutex_unlock(&dir->d_inode->i_mutex);
dput(victim);
//_leave(" = 0");
return 0;
}

134
fs/cachefiles/proc.c Normal file
View File

@ -0,0 +1,134 @@
/* CacheFiles statistics
*
* Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public Licence
* as published by the Free Software Foundation; either version
* 2 of the Licence, or (at your option) any later version.
*/
#include <linux/module.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include "internal.h"
atomic_t cachefiles_lookup_histogram[HZ];
atomic_t cachefiles_mkdir_histogram[HZ];
atomic_t cachefiles_create_histogram[HZ];
/*
* display the latency histogram
*/
static int cachefiles_histogram_show(struct seq_file *m, void *v)
{
unsigned long index;
unsigned x, y, z, t;
switch ((unsigned long) v) {
case 1:
seq_puts(m, "JIFS SECS LOOKUPS MKDIRS CREATES\n");
return 0;
case 2:
seq_puts(m, "===== ===== ========= ========= =========\n");
return 0;
default:
index = (unsigned long) v - 3;
x = atomic_read(&cachefiles_lookup_histogram[index]);
y = atomic_read(&cachefiles_mkdir_histogram[index]);
z = atomic_read(&cachefiles_create_histogram[index]);
if (x == 0 && y == 0 && z == 0)
return 0;
t = (index * 1000) / HZ;
seq_printf(m, "%4lu 0.%03u %9u %9u %9u\n", index, t, x, y, z);
return 0;
}
}
/*
* set up the iterator to start reading from the first line
*/
static void *cachefiles_histogram_start(struct seq_file *m, loff_t *_pos)
{
if ((unsigned long long)*_pos >= HZ + 2)
return NULL;
if (*_pos == 0)
*_pos = 1;
return (void *)(unsigned long) *_pos;
}
/*
* move to the next line
*/
static void *cachefiles_histogram_next(struct seq_file *m, void *v, loff_t *pos)
{
(*pos)++;
return (unsigned long long)*pos > HZ + 2 ?
NULL : (void *)(unsigned long) *pos;
}
/*
* clean up after reading
*/
static void cachefiles_histogram_stop(struct seq_file *m, void *v)
{
}
static const struct seq_operations cachefiles_histogram_ops = {
.start = cachefiles_histogram_start,
.stop = cachefiles_histogram_stop,
.next = cachefiles_histogram_next,
.show = cachefiles_histogram_show,
};
/*
* open "/proc/fs/cachefiles/XXX" which provide statistics summaries
*/
static int cachefiles_histogram_open(struct inode *inode, struct file *file)
{
return seq_open(file, &cachefiles_histogram_ops);
}
static const struct file_operations cachefiles_histogram_fops = {
.owner = THIS_MODULE,
.open = cachefiles_histogram_open,
.read = seq_read,
.llseek = seq_lseek,
.release = seq_release,
};
/*
* initialise the /proc/fs/cachefiles/ directory
*/
int __init cachefiles_proc_init(void)
{
_enter("");
if (!proc_mkdir("fs/cachefiles", NULL))
goto error_dir;
if (!proc_create("fs/cachefiles/histogram", S_IFREG | 0444, NULL,
&cachefiles_histogram_fops))
goto error_histogram;
_leave(" = 0");
return 0;
error_histogram:
remove_proc_entry("fs/cachefiles", NULL);
error_dir:
_leave(" = -ENOMEM");
return -ENOMEM;
}
/*
* clean up the /proc/fs/cachefiles/ directory
*/
void cachefiles_proc_cleanup(void)
{
remove_proc_entry("fs/cachefiles/histogram", NULL);
remove_proc_entry("fs/cachefiles", NULL);
}

879
fs/cachefiles/rdwr.c Normal file
View File

@ -0,0 +1,879 @@
/* Storage object read/write
*
* Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public Licence
* as published by the Free Software Foundation; either version
* 2 of the Licence, or (at your option) any later version.
*/
#include <linux/mount.h>
#include <linux/file.h>
#include "internal.h"
/*
* detect wake up events generated by the unlocking of pages in which we're
* interested
* - we use this to detect read completion of backing pages
* - the caller holds the waitqueue lock
*/
static int cachefiles_read_waiter(wait_queue_t *wait, unsigned mode,
int sync, void *_key)
{
struct cachefiles_one_read *monitor =
container_of(wait, struct cachefiles_one_read, monitor);
struct cachefiles_object *object;
struct wait_bit_key *key = _key;
struct page *page = wait->private;
ASSERT(key);
_enter("{%lu},%u,%d,{%p,%u}",
monitor->netfs_page->index, mode, sync,
key->flags, key->bit_nr);
if (key->flags != &page->flags ||
key->bit_nr != PG_locked)
return 0;
_debug("--- monitor %p %lx ---", page, page->flags);
if (!PageUptodate(page) && !PageError(page))
dump_stack();
/* remove from the waitqueue */
list_del(&wait->task_list);
/* move onto the action list and queue for FS-Cache thread pool */
ASSERT(monitor->op);
object = container_of(monitor->op->op.object,
struct cachefiles_object, fscache);
spin_lock(&object->work_lock);
list_add_tail(&monitor->op_link, &monitor->op->to_do);
spin_unlock(&object->work_lock);
fscache_enqueue_retrieval(monitor->op);
return 0;
}
/*
* copy data from backing pages to netfs pages to complete a read operation
* - driven by FS-Cache's thread pool
*/
static void cachefiles_read_copier(struct fscache_operation *_op)
{
struct cachefiles_one_read *monitor;
struct cachefiles_object *object;
struct fscache_retrieval *op;
struct pagevec pagevec;
int error, max;
op = container_of(_op, struct fscache_retrieval, op);
object = container_of(op->op.object,
struct cachefiles_object, fscache);
_enter("{ino=%lu}", object->backer->d_inode->i_ino);
pagevec_init(&pagevec, 0);
max = 8;
spin_lock_irq(&object->work_lock);
while (!list_empty(&op->to_do)) {
monitor = list_entry(op->to_do.next,
struct cachefiles_one_read, op_link);
list_del(&monitor->op_link);
spin_unlock_irq(&object->work_lock);
_debug("- copy {%lu}", monitor->back_page->index);
error = -EIO;
if (PageUptodate(monitor->back_page)) {
copy_highpage(monitor->netfs_page, monitor->back_page);
pagevec_add(&pagevec, monitor->netfs_page);
fscache_mark_pages_cached(monitor->op, &pagevec);
error = 0;
}
if (error)
cachefiles_io_error_obj(
object,
"Readpage failed on backing file %lx",
(unsigned long) monitor->back_page->flags);
page_cache_release(monitor->back_page);
fscache_end_io(op, monitor->netfs_page, error);
page_cache_release(monitor->netfs_page);
fscache_put_retrieval(op);
kfree(monitor);
/* let the thread pool have some air occasionally */
max--;
if (max < 0 || need_resched()) {
if (!list_empty(&op->to_do))
fscache_enqueue_retrieval(op);
_leave(" [maxed out]");
return;
}
spin_lock_irq(&object->work_lock);
}
spin_unlock_irq(&object->work_lock);
_leave("");
}
/*
* read the corresponding page to the given set from the backing file
* - an uncertain page is simply discarded, to be tried again another time
*/
static int cachefiles_read_backing_file_one(struct cachefiles_object *object,
struct fscache_retrieval *op,
struct page *netpage,
struct pagevec *pagevec)
{
struct cachefiles_one_read *monitor;
struct address_space *bmapping;
struct page *newpage, *backpage;
int ret;
_enter("");
pagevec_reinit(pagevec);
_debug("read back %p{%lu,%d}",
netpage, netpage->index, page_count(netpage));
monitor = kzalloc(sizeof(*monitor), GFP_KERNEL);
if (!monitor)
goto nomem;
monitor->netfs_page = netpage;
monitor->op = fscache_get_retrieval(op);
init_waitqueue_func_entry(&monitor->monitor, cachefiles_read_waiter);
/* attempt to get hold of the backing page */
bmapping = object->backer->d_inode->i_mapping;
newpage = NULL;
for (;;) {
backpage = find_get_page(bmapping, netpage->index);
if (backpage)
goto backing_page_already_present;
if (!newpage) {
newpage = page_cache_alloc_cold(bmapping);
if (!newpage)
goto nomem_monitor;
}
ret = add_to_page_cache(newpage, bmapping,
netpage->index, GFP_KERNEL);
if (ret == 0)
goto installed_new_backing_page;
if (ret != -EEXIST)
goto nomem_page;
}
/* we've installed a new backing page, so now we need to add it
* to the LRU list and start it reading */
installed_new_backing_page:
_debug("- new %p", newpage);
backpage = newpage;
newpage = NULL;
page_cache_get(backpage);
pagevec_add(pagevec, backpage);
__pagevec_lru_add_file(pagevec);
read_backing_page:
ret = bmapping->a_ops->readpage(NULL, backpage);
if (ret < 0)
goto read_error;
/* set the monitor to transfer the data across */
monitor_backing_page:
_debug("- monitor add");
/* install the monitor */
page_cache_get(monitor->netfs_page);
page_cache_get(backpage);
monitor->back_page = backpage;
monitor->monitor.private = backpage;
add_page_wait_queue(backpage, &monitor->monitor);
monitor = NULL;
/* but the page may have been read before the monitor was installed, so
* the monitor may miss the event - so we have to ensure that we do get
* one in such a case */
if (trylock_page(backpage)) {
_debug("jumpstart %p {%lx}", backpage, backpage->flags);
unlock_page(backpage);
}
goto success;
/* if the backing page is already present, it can be in one of
* three states: read in progress, read failed or read okay */
backing_page_already_present:
_debug("- present");
if (newpage) {
page_cache_release(newpage);
newpage = NULL;
}
if (PageError(backpage))
goto io_error;
if (PageUptodate(backpage))
goto backing_page_already_uptodate;
if (!trylock_page(backpage))
goto monitor_backing_page;
_debug("read %p {%lx}", backpage, backpage->flags);
goto read_backing_page;
/* the backing page is already up to date, attach the netfs
* page to the pagecache and LRU and copy the data across */
backing_page_already_uptodate:
_debug("- uptodate");
pagevec_add(pagevec, netpage);
fscache_mark_pages_cached(op, pagevec);
copy_highpage(netpage, backpage);
fscache_end_io(op, netpage, 0);
success:
_debug("success");
ret = 0;
out:
if (backpage)
page_cache_release(backpage);
if (monitor) {
fscache_put_retrieval(monitor->op);
kfree(monitor);
}
_leave(" = %d", ret);
return ret;
read_error:
_debug("read error %d", ret);
if (ret == -ENOMEM)
goto out;
io_error:
cachefiles_io_error_obj(object, "Page read error on backing file");
ret = -ENOBUFS;
goto out;
nomem_page:
page_cache_release(newpage);
nomem_monitor:
fscache_put_retrieval(monitor->op);
kfree(monitor);
nomem:
_leave(" = -ENOMEM");
return -ENOMEM;
}
/*
* read a page from the cache or allocate a block in which to store it
* - cache withdrawal is prevented by the caller
* - returns -EINTR if interrupted
* - returns -ENOMEM if ran out of memory
* - returns -ENOBUFS if no buffers can be made available
* - returns -ENOBUFS if page is beyond EOF
* - if the page is backed by a block in the cache:
* - a read will be started which will call the callback on completion
* - 0 will be returned
* - else if the page is unbacked:
* - the metadata will be retained
* - -ENODATA will be returned
*/
int cachefiles_read_or_alloc_page(struct fscache_retrieval *op,
struct page *page,
gfp_t gfp)
{
struct cachefiles_object *object;
struct cachefiles_cache *cache;
struct pagevec pagevec;
struct inode *inode;
sector_t block0, block;
unsigned shift;
int ret;
object = container_of(op->op.object,
struct cachefiles_object, fscache);
cache = container_of(object->fscache.cache,
struct cachefiles_cache, cache);
_enter("{%p},{%lx},,,", object, page->index);
if (!object->backer)
return -ENOBUFS;
inode = object->backer->d_inode;
ASSERT(S_ISREG(inode->i_mode));
ASSERT(inode->i_mapping->a_ops->bmap);
ASSERT(inode->i_mapping->a_ops->readpages);
/* calculate the shift required to use bmap */
if (inode->i_sb->s_blocksize > PAGE_SIZE)
return -ENOBUFS;
shift = PAGE_SHIFT - inode->i_sb->s_blocksize_bits;
op->op.flags = FSCACHE_OP_FAST;
op->op.processor = cachefiles_read_copier;
pagevec_init(&pagevec, 0);
/* we assume the absence or presence of the first block is a good
* enough indication for the page as a whole
* - TODO: don't use bmap() for this as it is _not_ actually good
* enough for this as it doesn't indicate errors, but it's all we've
* got for the moment
*/
block0 = page->index;
block0 <<= shift;
block = inode->i_mapping->a_ops->bmap(inode->i_mapping, block0);
_debug("%llx -> %llx",
(unsigned long long) block0,
(unsigned long long) block);
if (block) {
/* submit the apparently valid page to the backing fs to be
* read from disk */
ret = cachefiles_read_backing_file_one(object, op, page,
&pagevec);
} else if (cachefiles_has_space(cache, 0, 1) == 0) {
/* there's space in the cache we can use */
pagevec_add(&pagevec, page);
fscache_mark_pages_cached(op, &pagevec);
ret = -ENODATA;
} else {
ret = -ENOBUFS;
}
_leave(" = %d", ret);
return ret;
}
/*
* read the corresponding pages to the given set from the backing file
* - any uncertain pages are simply discarded, to be tried again another time
*/
static int cachefiles_read_backing_file(struct cachefiles_object *object,
struct fscache_retrieval *op,
struct list_head *list,
struct pagevec *mark_pvec)
{
struct cachefiles_one_read *monitor = NULL;
struct address_space *bmapping = object->backer->d_inode->i_mapping;
struct pagevec lru_pvec;
struct page *newpage = NULL, *netpage, *_n, *backpage = NULL;
int ret = 0;
_enter("");
pagevec_init(&lru_pvec, 0);
list_for_each_entry_safe(netpage, _n, list, lru) {
list_del(&netpage->lru);
_debug("read back %p{%lu,%d}",
netpage, netpage->index, page_count(netpage));
if (!monitor) {
monitor = kzalloc(sizeof(*monitor), GFP_KERNEL);
if (!monitor)
goto nomem;
monitor->op = fscache_get_retrieval(op);
init_waitqueue_func_entry(&monitor->monitor,
cachefiles_read_waiter);
}
for (;;) {
backpage = find_get_page(bmapping, netpage->index);
if (backpage)
goto backing_page_already_present;
if (!newpage) {
newpage = page_cache_alloc_cold(bmapping);
if (!newpage)
goto nomem;
}
ret = add_to_page_cache(newpage, bmapping,
netpage->index, GFP_KERNEL);
if (ret == 0)
goto installed_new_backing_page;
if (ret != -EEXIST)
goto nomem;
}
/* we've installed a new backing page, so now we need to add it
* to the LRU list and start it reading */
installed_new_backing_page:
_debug("- new %p", newpage);
backpage = newpage;
newpage = NULL;
page_cache_get(backpage);
if (!pagevec_add(&lru_pvec, backpage))
__pagevec_lru_add_file(&lru_pvec);
reread_backing_page:
ret = bmapping->a_ops->readpage(NULL, backpage);
if (ret < 0)
goto read_error;
/* add the netfs page to the pagecache and LRU, and set the
* monitor to transfer the data across */
monitor_backing_page:
_debug("- monitor add");
ret = add_to_page_cache(netpage, op->mapping, netpage->index,
GFP_KERNEL);
if (ret < 0) {
if (ret == -EEXIST) {
page_cache_release(netpage);
continue;
}
goto nomem;
}
page_cache_get(netpage);
if (!pagevec_add(&lru_pvec, netpage))
__pagevec_lru_add_file(&lru_pvec);
/* install a monitor */
page_cache_get(netpage);
monitor->netfs_page = netpage;
page_cache_get(backpage);
monitor->back_page = backpage;
monitor->monitor.private = backpage;
add_page_wait_queue(backpage, &monitor->monitor);
monitor = NULL;
/* but the page may have been read before the monitor was
* installed, so the monitor may miss the event - so we have to
* ensure that we do get one in such a case */
if (trylock_page(backpage)) {
_debug("2unlock %p {%lx}", backpage, backpage->flags);
unlock_page(backpage);
}
page_cache_release(backpage);
backpage = NULL;
page_cache_release(netpage);
netpage = NULL;
continue;
/* if the backing page is already present, it can be in one of
* three states: read in progress, read failed or read okay */
backing_page_already_present:
_debug("- present %p", backpage);
if (PageError(backpage))
goto io_error;
if (PageUptodate(backpage))
goto backing_page_already_uptodate;
_debug("- not ready %p{%lx}", backpage, backpage->flags);
if (!trylock_page(backpage))
goto monitor_backing_page;
if (PageError(backpage)) {
_debug("error %lx", backpage->flags);
unlock_page(backpage);
goto io_error;
}
if (PageUptodate(backpage))
goto backing_page_already_uptodate_unlock;
/* we've locked a page that's neither up to date nor erroneous,
* so we need to attempt to read it again */
goto reread_backing_page;
/* the backing page is already up to date, attach the netfs
* page to the pagecache and LRU and copy the data across */
backing_page_already_uptodate_unlock:
_debug("uptodate %lx", backpage->flags);
unlock_page(backpage);
backing_page_already_uptodate:
_debug("- uptodate");
ret = add_to_page_cache(netpage, op->mapping, netpage->index,
GFP_KERNEL);
if (ret < 0) {
if (ret == -EEXIST) {
page_cache_release(netpage);
continue;
}
goto nomem;
}
copy_highpage(netpage, backpage);
page_cache_release(backpage);
backpage = NULL;
if (!pagevec_add(mark_pvec, netpage))
fscache_mark_pages_cached(op, mark_pvec);
page_cache_get(netpage);
if (!pagevec_add(&lru_pvec, netpage))
__pagevec_lru_add_file(&lru_pvec);
fscache_end_io(op, netpage, 0);
page_cache_release(netpage);
netpage = NULL;
continue;
}
netpage = NULL;
_debug("out");
out:
/* tidy up */
pagevec_lru_add_file(&lru_pvec);
if (newpage)
page_cache_release(newpage);
if (netpage)
page_cache_release(netpage);
if (backpage)
page_cache_release(backpage);
if (monitor) {
fscache_put_retrieval(op);
kfree(monitor);
}
list_for_each_entry_safe(netpage, _n, list, lru) {
list_del(&netpage->lru);
page_cache_release(netpage);
}
_leave(" = %d", ret);
return ret;
nomem:
_debug("nomem");
ret = -ENOMEM;
goto out;
read_error:
_debug("read error %d", ret);
if (ret == -ENOMEM)
goto out;
io_error:
cachefiles_io_error_obj(object, "Page read error on backing file");
ret = -ENOBUFS;
goto out;
}
/*
* read a list of pages from the cache or allocate blocks in which to store
* them
*/
int cachefiles_read_or_alloc_pages(struct fscache_retrieval *op,
struct list_head *pages,
unsigned *nr_pages,
gfp_t gfp)
{
struct cachefiles_object *object;
struct cachefiles_cache *cache;
struct list_head backpages;
struct pagevec pagevec;
struct inode *inode;
struct page *page, *_n;
unsigned shift, nrbackpages;
int ret, ret2, space;
object = container_of(op->op.object,
struct cachefiles_object, fscache);
cache = container_of(object->fscache.cache,
struct cachefiles_cache, cache);
_enter("{OBJ%x,%d},,%d,,",
object->fscache.debug_id, atomic_read(&op->op.usage),
*nr_pages);
if (!object->backer)
return -ENOBUFS;
space = 1;
if (cachefiles_has_space(cache, 0, *nr_pages) < 0)
space = 0;
inode = object->backer->d_inode;
ASSERT(S_ISREG(inode->i_mode));
ASSERT(inode->i_mapping->a_ops->bmap);
ASSERT(inode->i_mapping->a_ops->readpages);
/* calculate the shift required to use bmap */
if (inode->i_sb->s_blocksize > PAGE_SIZE)
return -ENOBUFS;
shift = PAGE_SHIFT - inode->i_sb->s_blocksize_bits;
pagevec_init(&pagevec, 0);
op->op.flags = FSCACHE_OP_FAST;
op->op.processor = cachefiles_read_copier;
INIT_LIST_HEAD(&backpages);
nrbackpages = 0;
ret = space ? -ENODATA : -ENOBUFS;
list_for_each_entry_safe(page, _n, pages, lru) {
sector_t block0, block;
/* we assume the absence or presence of the first block is a
* good enough indication for the page as a whole
* - TODO: don't use bmap() for this as it is _not_ actually
* good enough for this as it doesn't indicate errors, but
* it's all we've got for the moment
*/
block0 = page->index;
block0 <<= shift;
block = inode->i_mapping->a_ops->bmap(inode->i_mapping,
block0);
_debug("%llx -> %llx",
(unsigned long long) block0,
(unsigned long long) block);
if (block) {
/* we have data - add it to the list to give to the
* backing fs */
list_move(&page->lru, &backpages);
(*nr_pages)--;
nrbackpages++;
} else if (space && pagevec_add(&pagevec, page) == 0) {
fscache_mark_pages_cached(op, &pagevec);
ret = -ENODATA;
}
}
if (pagevec_count(&pagevec) > 0)
fscache_mark_pages_cached(op, &pagevec);
if (list_empty(pages))
ret = 0;
/* submit the apparently valid pages to the backing fs to be read from
* disk */
if (nrbackpages > 0) {
ret2 = cachefiles_read_backing_file(object, op, &backpages,
&pagevec);
if (ret2 == -ENOMEM || ret2 == -EINTR)
ret = ret2;
}
if (pagevec_count(&pagevec) > 0)
fscache_mark_pages_cached(op, &pagevec);
_leave(" = %d [nr=%u%s]",
ret, *nr_pages, list_empty(pages) ? " empty" : "");
return ret;
}
/*
* allocate a block in the cache in which to store a page
* - cache withdrawal is prevented by the caller
* - returns -EINTR if interrupted
* - returns -ENOMEM if ran out of memory
* - returns -ENOBUFS if no buffers can be made available
* - returns -ENOBUFS if page is beyond EOF
* - otherwise:
* - the metadata will be retained
* - 0 will be returned
*/
int cachefiles_allocate_page(struct fscache_retrieval *op,
struct page *page,
gfp_t gfp)
{
struct cachefiles_object *object;
struct cachefiles_cache *cache;
struct pagevec pagevec;
int ret;
object = container_of(op->op.object,
struct cachefiles_object, fscache);
cache = container_of(object->fscache.cache,
struct cachefiles_cache, cache);
_enter("%p,{%lx},", object, page->index);
ret = cachefiles_has_space(cache, 0, 1);
if (ret == 0) {
pagevec_init(&pagevec, 0);
pagevec_add(&pagevec, page);
fscache_mark_pages_cached(op, &pagevec);
} else {
ret = -ENOBUFS;
}
_leave(" = %d", ret);
return ret;
}
/*
* allocate blocks in the cache in which to store a set of pages
* - cache withdrawal is prevented by the caller
* - returns -EINTR if interrupted
* - returns -ENOMEM if ran out of memory
* - returns -ENOBUFS if some buffers couldn't be made available
* - returns -ENOBUFS if some pages are beyond EOF
* - otherwise:
* - -ENODATA will be returned
* - metadata will be retained for any page marked
*/
int cachefiles_allocate_pages(struct fscache_retrieval *op,
struct list_head *pages,
unsigned *nr_pages,
gfp_t gfp)
{
struct cachefiles_object *object;
struct cachefiles_cache *cache;
struct pagevec pagevec;
struct page *page;
int ret;
object = container_of(op->op.object,
struct cachefiles_object, fscache);
cache = container_of(object->fscache.cache,
struct cachefiles_cache, cache);
_enter("%p,,,%d,", object, *nr_pages);
ret = cachefiles_has_space(cache, 0, *nr_pages);
if (ret == 0) {
pagevec_init(&pagevec, 0);
list_for_each_entry(page, pages, lru) {
if (pagevec_add(&pagevec, page) == 0)
fscache_mark_pages_cached(op, &pagevec);
}
if (pagevec_count(&pagevec) > 0)
fscache_mark_pages_cached(op, &pagevec);
ret = -ENODATA;
} else {
ret = -ENOBUFS;
}
_leave(" = %d", ret);
return ret;
}
/*
* request a page be stored in the cache
* - cache withdrawal is prevented by the caller
* - this request may be ignored if there's no cache block available, in which
* case -ENOBUFS will be returned
* - if the op is in progress, 0 will be returned
*/
int cachefiles_write_page(struct fscache_storage *op, struct page *page)
{
struct cachefiles_object *object;
struct cachefiles_cache *cache;
mm_segment_t old_fs;
struct file *file;
loff_t pos;
void *data;
int ret;
ASSERT(op != NULL);
ASSERT(page != NULL);
object = container_of(op->op.object,
struct cachefiles_object, fscache);
_enter("%p,%p{%lx},,,", object, page, page->index);
if (!object->backer) {
_leave(" = -ENOBUFS");
return -ENOBUFS;
}
ASSERT(S_ISREG(object->backer->d_inode->i_mode));
cache = container_of(object->fscache.cache,
struct cachefiles_cache, cache);
/* write the page to the backing filesystem and let it store it in its
* own time */
dget(object->backer);
mntget(cache->mnt);
file = dentry_open(object->backer, cache->mnt, O_RDWR,
cache->cache_cred);
if (IS_ERR(file)) {
ret = PTR_ERR(file);
} else {
ret = -EIO;
if (file->f_op->write) {
pos = (loff_t) page->index << PAGE_SHIFT;
data = kmap(page);
old_fs = get_fs();
set_fs(KERNEL_DS);
ret = file->f_op->write(
file, (const void __user *) data, PAGE_SIZE,
&pos);
set_fs(old_fs);
kunmap(page);
if (ret != PAGE_SIZE)
ret = -EIO;
}
fput(file);
}
if (ret < 0) {
if (ret == -EIO)
cachefiles_io_error_obj(
object, "Write page to backing file failed");
ret = -ENOBUFS;
}
_leave(" = %d", ret);
return ret;
}
/*
* detach a backing block from a page
* - cache withdrawal is prevented by the caller
*/
void cachefiles_uncache_page(struct fscache_object *_object, struct page *page)
{
struct cachefiles_object *object;
struct cachefiles_cache *cache;
object = container_of(_object, struct cachefiles_object, fscache);
cache = container_of(object->fscache.cache,
struct cachefiles_cache, cache);
_enter("%p,{%lu}", object, page->index);
spin_unlock(&object->fscache.cookie->lock);
}

116
fs/cachefiles/security.c Normal file
View File

@ -0,0 +1,116 @@
/* CacheFiles security management
*
* Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public Licence
* as published by the Free Software Foundation; either version
* 2 of the Licence, or (at your option) any later version.
*/
#include <linux/fs.h>
#include <linux/cred.h>
#include "internal.h"
/*
* determine the security context within which we access the cache from within
* the kernel
*/
int cachefiles_get_security_ID(struct cachefiles_cache *cache)
{
struct cred *new;
int ret;
_enter("{%s}", cache->secctx);
new = prepare_kernel_cred(current);
if (!new) {
ret = -ENOMEM;
goto error;
}
if (cache->secctx) {
ret = set_security_override_from_ctx(new, cache->secctx);
if (ret < 0) {
put_cred(new);
printk(KERN_ERR "CacheFiles:"
" Security denies permission to nominate"
" security context: error %d\n",
ret);
goto error;
}
}
cache->cache_cred = new;
ret = 0;
error:
_leave(" = %d", ret);
return ret;
}
/*
* see if mkdir and create can be performed in the root directory
*/
static int cachefiles_check_cache_dir(struct cachefiles_cache *cache,
struct dentry *root)
{
int ret;
ret = security_inode_mkdir(root->d_inode, root, 0);
if (ret < 0) {
printk(KERN_ERR "CacheFiles:"
" Security denies permission to make dirs: error %d",
ret);
return ret;
}
ret = security_inode_create(root->d_inode, root, 0);
if (ret < 0)
printk(KERN_ERR "CacheFiles:"
" Security denies permission to create files: error %d",
ret);
return ret;
}
/*
* check the security details of the on-disk cache
* - must be called with security override in force
*/
int cachefiles_determine_cache_security(struct cachefiles_cache *cache,
struct dentry *root,
const struct cred **_saved_cred)
{
struct cred *new;
int ret;
_enter("");
/* duplicate the cache creds for COW (the override is currently in
* force, so we can use prepare_creds() to do this) */
new = prepare_creds();
if (!new)
return -ENOMEM;
cachefiles_end_secure(cache, *_saved_cred);
/* use the cache root dir's security context as the basis with
* which create files */
ret = set_create_files_as(new, root->d_inode);
if (ret < 0) {
_leave(" = %d [cfa]", ret);
return ret;
}
put_cred(cache->cache_cred);
cache->cache_cred = new;
cachefiles_begin_secure(cache, _saved_cred);
ret = cachefiles_check_cache_dir(cache, root);
if (ret == -EOPNOTSUPP)
ret = 0;
_leave(" = %d", ret);
return ret;
}

291
fs/cachefiles/xattr.c Normal file
View File

@ -0,0 +1,291 @@
/* CacheFiles extended attribute management
*
* Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public Licence
* as published by the Free Software Foundation; either version
* 2 of the Licence, or (at your option) any later version.
*/
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/file.h>
#include <linux/fs.h>
#include <linux/fsnotify.h>
#include <linux/quotaops.h>
#include <linux/xattr.h>
#include "internal.h"
static const char cachefiles_xattr_cache[] =
XATTR_USER_PREFIX "CacheFiles.cache";
/*
* check the type label on an object
* - done using xattrs
*/
int cachefiles_check_object_type(struct cachefiles_object *object)
{
struct dentry *dentry = object->dentry;
char type[3], xtype[3];
int ret;
ASSERT(dentry);
ASSERT(dentry->d_inode);
if (!object->fscache.cookie)
strcpy(type, "C3");
else
snprintf(type, 3, "%02x", object->fscache.cookie->def->type);
_enter("%p{%s}", object, type);
/* attempt to install a type label directly */
ret = vfs_setxattr(dentry, cachefiles_xattr_cache, type, 2,
XATTR_CREATE);
if (ret == 0) {
_debug("SET"); /* we succeeded */
goto error;
}
if (ret != -EEXIST) {
kerror("Can't set xattr on %*.*s [%lu] (err %d)",
dentry->d_name.len, dentry->d_name.len,
dentry->d_name.name, dentry->d_inode->i_ino,
-ret);
goto error;
}
/* read the current type label */
ret = vfs_getxattr(dentry, cachefiles_xattr_cache, xtype, 3);
if (ret < 0) {
if (ret == -ERANGE)
goto bad_type_length;
kerror("Can't read xattr on %*.*s [%lu] (err %d)",
dentry->d_name.len, dentry->d_name.len,
dentry->d_name.name, dentry->d_inode->i_ino,
-ret);
goto error;
}
/* check the type is what we're expecting */
if (ret != 2)
goto bad_type_length;
if (xtype[0] != type[0] || xtype[1] != type[1])
goto bad_type;
ret = 0;
error:
_leave(" = %d", ret);
return ret;
bad_type_length:
kerror("Cache object %lu type xattr length incorrect",
dentry->d_inode->i_ino);
ret = -EIO;
goto error;
bad_type:
xtype[2] = 0;
kerror("Cache object %*.*s [%lu] type %s not %s",
dentry->d_name.len, dentry->d_name.len,
dentry->d_name.name, dentry->d_inode->i_ino,
xtype, type);
ret = -EIO;
goto error;
}
/*
* set the state xattr on a cache file
*/
int cachefiles_set_object_xattr(struct cachefiles_object *object,
struct cachefiles_xattr *auxdata)
{
struct dentry *dentry = object->dentry;
int ret;
ASSERT(object->fscache.cookie);
ASSERT(dentry);
_enter("%p,#%d", object, auxdata->len);
/* attempt to install the cache metadata directly */
_debug("SET %s #%u", object->fscache.cookie->def->name, auxdata->len);
ret = vfs_setxattr(dentry, cachefiles_xattr_cache,
&auxdata->type, auxdata->len,
XATTR_CREATE);
if (ret < 0 && ret != -ENOMEM)
cachefiles_io_error_obj(
object,
"Failed to set xattr with error %d", ret);
_leave(" = %d", ret);
return ret;
}
/*
* update the state xattr on a cache file
*/
int cachefiles_update_object_xattr(struct cachefiles_object *object,
struct cachefiles_xattr *auxdata)
{
struct dentry *dentry = object->dentry;
int ret;
ASSERT(object->fscache.cookie);
ASSERT(dentry);
_enter("%p,#%d", object, auxdata->len);
/* attempt to install the cache metadata directly */
_debug("SET %s #%u", object->fscache.cookie->def->name, auxdata->len);
ret = vfs_setxattr(dentry, cachefiles_xattr_cache,
&auxdata->type, auxdata->len,
XATTR_REPLACE);
if (ret < 0 && ret != -ENOMEM)
cachefiles_io_error_obj(
object,
"Failed to update xattr with error %d", ret);
_leave(" = %d", ret);
return ret;
}
/*
* check the state xattr on a cache file
* - return -ESTALE if the object should be deleted
*/
int cachefiles_check_object_xattr(struct cachefiles_object *object,
struct cachefiles_xattr *auxdata)
{
struct cachefiles_xattr *auxbuf;
struct dentry *dentry = object->dentry;
int ret;
_enter("%p,#%d", object, auxdata->len);
ASSERT(dentry);
ASSERT(dentry->d_inode);
auxbuf = kmalloc(sizeof(struct cachefiles_xattr) + 512, GFP_KERNEL);
if (!auxbuf) {
_leave(" = -ENOMEM");
return -ENOMEM;
}
/* read the current type label */
ret = vfs_getxattr(dentry, cachefiles_xattr_cache,
&auxbuf->type, 512 + 1);
if (ret < 0) {
if (ret == -ENODATA)
goto stale; /* no attribute - power went off
* mid-cull? */
if (ret == -ERANGE)
goto bad_type_length;
cachefiles_io_error_obj(object,
"Can't read xattr on %lu (err %d)",
dentry->d_inode->i_ino, -ret);
goto error;
}
/* check the on-disk object */
if (ret < 1)
goto bad_type_length;
if (auxbuf->type != auxdata->type)
goto stale;
auxbuf->len = ret;
/* consult the netfs */
if (object->fscache.cookie->def->check_aux) {
enum fscache_checkaux result;
unsigned int dlen;
dlen = auxbuf->len - 1;
_debug("checkaux %s #%u",
object->fscache.cookie->def->name, dlen);
result = fscache_check_aux(&object->fscache,
&auxbuf->data, dlen);
switch (result) {
/* entry okay as is */
case FSCACHE_CHECKAUX_OKAY:
goto okay;
/* entry requires update */
case FSCACHE_CHECKAUX_NEEDS_UPDATE:
break;
/* entry requires deletion */
case FSCACHE_CHECKAUX_OBSOLETE:
goto stale;
default:
BUG();
}
/* update the current label */
ret = vfs_setxattr(dentry, cachefiles_xattr_cache,
&auxdata->type, auxdata->len,
XATTR_REPLACE);
if (ret < 0) {
cachefiles_io_error_obj(object,
"Can't update xattr on %lu"
" (error %d)",
dentry->d_inode->i_ino, -ret);
goto error;
}
}
okay:
ret = 0;
error:
kfree(auxbuf);
_leave(" = %d", ret);
return ret;
bad_type_length:
kerror("Cache object %lu xattr length incorrect",
dentry->d_inode->i_ino);
ret = -EIO;
goto error;
stale:
ret = -ESTALE;
goto error;
}
/*
* remove the object's xattr to mark it stale
*/
int cachefiles_remove_object_xattr(struct cachefiles_cache *cache,
struct dentry *dentry)
{
int ret;
ret = vfs_removexattr(dentry, cachefiles_xattr_cache);
if (ret < 0) {
if (ret == -ENOENT || ret == -ENODATA)
ret = 0;
else if (ret != -ENOMEM)
cachefiles_io_error(cache,
"Can't remove xattr from %lu"
" (error %d)",
dentry->d_inode->i_ino, -ret);
}
_leave(" = %d", ret);
return ret;
}

56
fs/fscache/Kconfig Normal file
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@ -0,0 +1,56 @@
config FSCACHE
tristate "General filesystem local caching manager"
depends on EXPERIMENTAL
select SLOW_WORK
help
This option enables a generic filesystem caching manager that can be
used by various network and other filesystems to cache data locally.
Different sorts of caches can be plugged in, depending on the
resources available.
See Documentation/filesystems/caching/fscache.txt for more information.
config FSCACHE_STATS
bool "Gather statistical information on local caching"
depends on FSCACHE && PROC_FS
help
This option causes statistical information to be gathered on local
caching and exported through file:
/proc/fs/fscache/stats
The gathering of statistics adds a certain amount of overhead to
execution as there are a quite a few stats gathered, and on a
multi-CPU system these may be on cachelines that keep bouncing
between CPUs. On the other hand, the stats are very useful for
debugging purposes. Saying 'Y' here is recommended.
See Documentation/filesystems/caching/fscache.txt for more information.
config FSCACHE_HISTOGRAM
bool "Gather latency information on local caching"
depends on FSCACHE && PROC_FS
help
This option causes latency information to be gathered on local
caching and exported through file:
/proc/fs/fscache/histogram
The generation of this histogram adds a certain amount of overhead to
execution as there are a number of points at which data is gathered,
and on a multi-CPU system these may be on cachelines that keep
bouncing between CPUs. On the other hand, the histogram may be
useful for debugging purposes. Saying 'N' here is recommended.
See Documentation/filesystems/caching/fscache.txt for more information.
config FSCACHE_DEBUG
bool "Debug FS-Cache"
depends on FSCACHE
help
This permits debugging to be dynamically enabled in the local caching
management module. If this is set, the debugging output may be
enabled by setting bits in /sys/modules/fscache/parameter/debug.
See Documentation/filesystems/caching/fscache.txt for more information.

19
fs/fscache/Makefile Normal file
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@ -0,0 +1,19 @@
#
# Makefile for general filesystem caching code
#
fscache-y := \
cache.o \
cookie.o \
fsdef.o \
main.o \
netfs.o \
object.o \
operation.o \
page.o
fscache-$(CONFIG_PROC_FS) += proc.o
fscache-$(CONFIG_FSCACHE_STATS) += stats.o
fscache-$(CONFIG_FSCACHE_HISTOGRAM) += histogram.o
obj-$(CONFIG_FSCACHE) := fscache.o

415
fs/fscache/cache.c Normal file
View File

@ -0,0 +1,415 @@
/* FS-Cache cache handling
*
* Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#define FSCACHE_DEBUG_LEVEL CACHE
#include <linux/module.h>
#include <linux/slab.h>
#include "internal.h"
LIST_HEAD(fscache_cache_list);
DECLARE_RWSEM(fscache_addremove_sem);
DECLARE_WAIT_QUEUE_HEAD(fscache_cache_cleared_wq);
EXPORT_SYMBOL(fscache_cache_cleared_wq);
static LIST_HEAD(fscache_cache_tag_list);
/*
* look up a cache tag
*/
struct fscache_cache_tag *__fscache_lookup_cache_tag(const char *name)
{
struct fscache_cache_tag *tag, *xtag;
/* firstly check for the existence of the tag under read lock */
down_read(&fscache_addremove_sem);
list_for_each_entry(tag, &fscache_cache_tag_list, link) {
if (strcmp(tag->name, name) == 0) {
atomic_inc(&tag->usage);
up_read(&fscache_addremove_sem);
return tag;
}
}
up_read(&fscache_addremove_sem);
/* the tag does not exist - create a candidate */
xtag = kzalloc(sizeof(*xtag) + strlen(name) + 1, GFP_KERNEL);
if (!xtag)
/* return a dummy tag if out of memory */
return ERR_PTR(-ENOMEM);
atomic_set(&xtag->usage, 1);
strcpy(xtag->name, name);
/* write lock, search again and add if still not present */
down_write(&fscache_addremove_sem);
list_for_each_entry(tag, &fscache_cache_tag_list, link) {
if (strcmp(tag->name, name) == 0) {
atomic_inc(&tag->usage);
up_write(&fscache_addremove_sem);
kfree(xtag);
return tag;
}
}
list_add_tail(&xtag->link, &fscache_cache_tag_list);
up_write(&fscache_addremove_sem);
return xtag;
}
/*
* release a reference to a cache tag
*/
void __fscache_release_cache_tag(struct fscache_cache_tag *tag)
{
if (tag != ERR_PTR(-ENOMEM)) {
down_write(&fscache_addremove_sem);
if (atomic_dec_and_test(&tag->usage))
list_del_init(&tag->link);
else
tag = NULL;
up_write(&fscache_addremove_sem);
kfree(tag);
}
}
/*
* select a cache in which to store an object
* - the cache addremove semaphore must be at least read-locked by the caller
* - the object will never be an index
*/
struct fscache_cache *fscache_select_cache_for_object(
struct fscache_cookie *cookie)
{
struct fscache_cache_tag *tag;
struct fscache_object *object;
struct fscache_cache *cache;
_enter("");
if (list_empty(&fscache_cache_list)) {
_leave(" = NULL [no cache]");
return NULL;
}
/* we check the parent to determine the cache to use */
spin_lock(&cookie->lock);
/* the first in the parent's backing list should be the preferred
* cache */
if (!hlist_empty(&cookie->backing_objects)) {
object = hlist_entry(cookie->backing_objects.first,
struct fscache_object, cookie_link);
cache = object->cache;
if (object->state >= FSCACHE_OBJECT_DYING ||
test_bit(FSCACHE_IOERROR, &cache->flags))
cache = NULL;
spin_unlock(&cookie->lock);
_leave(" = %p [parent]", cache);
return cache;
}
/* the parent is unbacked */
if (cookie->def->type != FSCACHE_COOKIE_TYPE_INDEX) {
/* cookie not an index and is unbacked */
spin_unlock(&cookie->lock);
_leave(" = NULL [cookie ub,ni]");
return NULL;
}
spin_unlock(&cookie->lock);
if (!cookie->def->select_cache)
goto no_preference;
/* ask the netfs for its preference */
tag = cookie->def->select_cache(cookie->parent->netfs_data,
cookie->netfs_data);
if (!tag)
goto no_preference;
if (tag == ERR_PTR(-ENOMEM)) {
_leave(" = NULL [nomem tag]");
return NULL;
}
if (!tag->cache) {
_leave(" = NULL [unbacked tag]");
return NULL;
}
if (test_bit(FSCACHE_IOERROR, &tag->cache->flags))
return NULL;
_leave(" = %p [specific]", tag->cache);
return tag->cache;
no_preference:
/* netfs has no preference - just select first cache */
cache = list_entry(fscache_cache_list.next,
struct fscache_cache, link);
_leave(" = %p [first]", cache);
return cache;
}
/**
* fscache_init_cache - Initialise a cache record
* @cache: The cache record to be initialised
* @ops: The cache operations to be installed in that record
* @idfmt: Format string to define identifier
* @...: sprintf-style arguments
*
* Initialise a record of a cache and fill in the name.
*
* See Documentation/filesystems/caching/backend-api.txt for a complete
* description.
*/
void fscache_init_cache(struct fscache_cache *cache,
const struct fscache_cache_ops *ops,
const char *idfmt,
...)
{
va_list va;
memset(cache, 0, sizeof(*cache));
cache->ops = ops;
va_start(va, idfmt);
vsnprintf(cache->identifier, sizeof(cache->identifier), idfmt, va);
va_end(va);
INIT_WORK(&cache->op_gc, fscache_operation_gc);
INIT_LIST_HEAD(&cache->link);
INIT_LIST_HEAD(&cache->object_list);
INIT_LIST_HEAD(&cache->op_gc_list);
spin_lock_init(&cache->object_list_lock);
spin_lock_init(&cache->op_gc_list_lock);
}
EXPORT_SYMBOL(fscache_init_cache);
/**
* fscache_add_cache - Declare a cache as being open for business
* @cache: The record describing the cache
* @ifsdef: The record of the cache object describing the top-level index
* @tagname: The tag describing this cache
*
* Add a cache to the system, making it available for netfs's to use.
*
* See Documentation/filesystems/caching/backend-api.txt for a complete
* description.
*/
int fscache_add_cache(struct fscache_cache *cache,
struct fscache_object *ifsdef,
const char *tagname)
{
struct fscache_cache_tag *tag;
BUG_ON(!cache->ops);
BUG_ON(!ifsdef);
cache->flags = 0;
ifsdef->event_mask = ULONG_MAX & ~(1 << FSCACHE_OBJECT_EV_CLEARED);
ifsdef->state = FSCACHE_OBJECT_ACTIVE;
if (!tagname)
tagname = cache->identifier;
BUG_ON(!tagname[0]);
_enter("{%s.%s},,%s", cache->ops->name, cache->identifier, tagname);
/* we use the cache tag to uniquely identify caches */
tag = __fscache_lookup_cache_tag(tagname);
if (IS_ERR(tag))
goto nomem;
if (test_and_set_bit(FSCACHE_TAG_RESERVED, &tag->flags))
goto tag_in_use;
cache->kobj = kobject_create_and_add(tagname, fscache_root);
if (!cache->kobj)
goto error;
ifsdef->cookie = &fscache_fsdef_index;
ifsdef->cache = cache;
cache->fsdef = ifsdef;
down_write(&fscache_addremove_sem);
tag->cache = cache;
cache->tag = tag;
/* add the cache to the list */
list_add(&cache->link, &fscache_cache_list);
/* add the cache's netfs definition index object to the cache's
* list */
spin_lock(&cache->object_list_lock);
list_add_tail(&ifsdef->cache_link, &cache->object_list);
spin_unlock(&cache->object_list_lock);
/* add the cache's netfs definition index object to the top level index
* cookie as a known backing object */
spin_lock(&fscache_fsdef_index.lock);
hlist_add_head(&ifsdef->cookie_link,
&fscache_fsdef_index.backing_objects);
atomic_inc(&fscache_fsdef_index.usage);
/* done */
spin_unlock(&fscache_fsdef_index.lock);
up_write(&fscache_addremove_sem);
printk(KERN_NOTICE "FS-Cache: Cache \"%s\" added (type %s)\n",
cache->tag->name, cache->ops->name);
kobject_uevent(cache->kobj, KOBJ_ADD);
_leave(" = 0 [%s]", cache->identifier);
return 0;
tag_in_use:
printk(KERN_ERR "FS-Cache: Cache tag '%s' already in use\n", tagname);
__fscache_release_cache_tag(tag);
_leave(" = -EXIST");
return -EEXIST;
error:
__fscache_release_cache_tag(tag);
_leave(" = -EINVAL");
return -EINVAL;
nomem:
_leave(" = -ENOMEM");
return -ENOMEM;
}
EXPORT_SYMBOL(fscache_add_cache);
/**
* fscache_io_error - Note a cache I/O error
* @cache: The record describing the cache
*
* Note that an I/O error occurred in a cache and that it should no longer be
* used for anything. This also reports the error into the kernel log.
*
* See Documentation/filesystems/caching/backend-api.txt for a complete
* description.
*/
void fscache_io_error(struct fscache_cache *cache)
{
set_bit(FSCACHE_IOERROR, &cache->flags);
printk(KERN_ERR "FS-Cache: Cache %s stopped due to I/O error\n",
cache->ops->name);
}
EXPORT_SYMBOL(fscache_io_error);
/*
* request withdrawal of all the objects in a cache
* - all the objects being withdrawn are moved onto the supplied list
*/
static void fscache_withdraw_all_objects(struct fscache_cache *cache,
struct list_head *dying_objects)
{
struct fscache_object *object;
spin_lock(&cache->object_list_lock);
while (!list_empty(&cache->object_list)) {
object = list_entry(cache->object_list.next,
struct fscache_object, cache_link);
list_move_tail(&object->cache_link, dying_objects);
_debug("withdraw %p", object->cookie);
spin_lock(&object->lock);
spin_unlock(&cache->object_list_lock);
fscache_raise_event(object, FSCACHE_OBJECT_EV_WITHDRAW);
spin_unlock(&object->lock);
cond_resched();
spin_lock(&cache->object_list_lock);
}
spin_unlock(&cache->object_list_lock);
}
/**
* fscache_withdraw_cache - Withdraw a cache from the active service
* @cache: The record describing the cache
*
* Withdraw a cache from service, unbinding all its cache objects from the
* netfs cookies they're currently representing.
*
* See Documentation/filesystems/caching/backend-api.txt for a complete
* description.
*/
void fscache_withdraw_cache(struct fscache_cache *cache)
{
LIST_HEAD(dying_objects);
_enter("");
printk(KERN_NOTICE "FS-Cache: Withdrawing cache \"%s\"\n",
cache->tag->name);
/* make the cache unavailable for cookie acquisition */
if (test_and_set_bit(FSCACHE_CACHE_WITHDRAWN, &cache->flags))
BUG();
down_write(&fscache_addremove_sem);
list_del_init(&cache->link);
cache->tag->cache = NULL;
up_write(&fscache_addremove_sem);
/* make sure all pages pinned by operations on behalf of the netfs are
* written to disk */
cache->ops->sync_cache(cache);
/* dissociate all the netfs pages backed by this cache from the block
* mappings in the cache */
cache->ops->dissociate_pages(cache);
/* we now have to destroy all the active objects pertaining to this
* cache - which we do by passing them off to thread pool to be
* disposed of */
_debug("destroy");
fscache_withdraw_all_objects(cache, &dying_objects);
/* wait for all extant objects to finish their outstanding operations
* and go away */
_debug("wait for finish");
wait_event(fscache_cache_cleared_wq,
atomic_read(&cache->object_count) == 0);
_debug("wait for clearance");
wait_event(fscache_cache_cleared_wq,
list_empty(&cache->object_list));
_debug("cleared");
ASSERT(list_empty(&dying_objects));
kobject_put(cache->kobj);
clear_bit(FSCACHE_TAG_RESERVED, &cache->tag->flags);
fscache_release_cache_tag(cache->tag);
cache->tag = NULL;
_leave("");
}
EXPORT_SYMBOL(fscache_withdraw_cache);

500
fs/fscache/cookie.c Normal file
View File

@ -0,0 +1,500 @@
/* netfs cookie management
*
* Copyright (C) 2004-2007 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*
* See Documentation/filesystems/caching/netfs-api.txt for more information on
* the netfs API.
*/
#define FSCACHE_DEBUG_LEVEL COOKIE
#include <linux/module.h>
#include <linux/slab.h>
#include "internal.h"
struct kmem_cache *fscache_cookie_jar;
static atomic_t fscache_object_debug_id = ATOMIC_INIT(0);
static int fscache_acquire_non_index_cookie(struct fscache_cookie *cookie);
static int fscache_alloc_object(struct fscache_cache *cache,
struct fscache_cookie *cookie);
static int fscache_attach_object(struct fscache_cookie *cookie,
struct fscache_object *object);
/*
* initialise an cookie jar slab element prior to any use
*/
void fscache_cookie_init_once(void *_cookie)
{
struct fscache_cookie *cookie = _cookie;
memset(cookie, 0, sizeof(*cookie));
spin_lock_init(&cookie->lock);
INIT_HLIST_HEAD(&cookie->backing_objects);
}
/*
* request a cookie to represent an object (index, datafile, xattr, etc)
* - parent specifies the parent object
* - the top level index cookie for each netfs is stored in the fscache_netfs
* struct upon registration
* - def points to the definition
* - the netfs_data will be passed to the functions pointed to in *def
* - all attached caches will be searched to see if they contain this object
* - index objects aren't stored on disk until there's a dependent file that
* needs storing
* - other objects are stored in a selected cache immediately, and all the
* indices forming the path to it are instantiated if necessary
* - we never let on to the netfs about errors
* - we may set a negative cookie pointer, but that's okay
*/
struct fscache_cookie *__fscache_acquire_cookie(
struct fscache_cookie *parent,
const struct fscache_cookie_def *def,
void *netfs_data)
{
struct fscache_cookie *cookie;
BUG_ON(!def);
_enter("{%s},{%s},%p",
parent ? (char *) parent->def->name : "<no-parent>",
def->name, netfs_data);
fscache_stat(&fscache_n_acquires);
/* if there's no parent cookie, then we don't create one here either */
if (!parent) {
fscache_stat(&fscache_n_acquires_null);
_leave(" [no parent]");
return NULL;
}
/* validate the definition */
BUG_ON(!def->get_key);
BUG_ON(!def->name[0]);
BUG_ON(def->type == FSCACHE_COOKIE_TYPE_INDEX &&
parent->def->type != FSCACHE_COOKIE_TYPE_INDEX);
/* allocate and initialise a cookie */
cookie = kmem_cache_alloc(fscache_cookie_jar, GFP_KERNEL);
if (!cookie) {
fscache_stat(&fscache_n_acquires_oom);
_leave(" [ENOMEM]");
return NULL;
}
atomic_set(&cookie->usage, 1);
atomic_set(&cookie->n_children, 0);
atomic_inc(&parent->usage);
atomic_inc(&parent->n_children);
cookie->def = def;
cookie->parent = parent;
cookie->netfs_data = netfs_data;
cookie->flags = 0;
INIT_RADIX_TREE(&cookie->stores, GFP_NOFS);
switch (cookie->def->type) {
case FSCACHE_COOKIE_TYPE_INDEX:
fscache_stat(&fscache_n_cookie_index);
break;
case FSCACHE_COOKIE_TYPE_DATAFILE:
fscache_stat(&fscache_n_cookie_data);
break;
default:
fscache_stat(&fscache_n_cookie_special);
break;
}
/* if the object is an index then we need do nothing more here - we
* create indices on disk when we need them as an index may exist in
* multiple caches */
if (cookie->def->type != FSCACHE_COOKIE_TYPE_INDEX) {
if (fscache_acquire_non_index_cookie(cookie) < 0) {
atomic_dec(&parent->n_children);
__fscache_cookie_put(cookie);
fscache_stat(&fscache_n_acquires_nobufs);
_leave(" = NULL");
return NULL;
}
}
fscache_stat(&fscache_n_acquires_ok);
_leave(" = %p", cookie);
return cookie;
}
EXPORT_SYMBOL(__fscache_acquire_cookie);
/*
* acquire a non-index cookie
* - this must make sure the index chain is instantiated and instantiate the
* object representation too
*/
static int fscache_acquire_non_index_cookie(struct fscache_cookie *cookie)
{
struct fscache_object *object;
struct fscache_cache *cache;
uint64_t i_size;
int ret;
_enter("");
cookie->flags = 1 << FSCACHE_COOKIE_UNAVAILABLE;
/* now we need to see whether the backing objects for this cookie yet
* exist, if not there'll be nothing to search */
down_read(&fscache_addremove_sem);
if (list_empty(&fscache_cache_list)) {
up_read(&fscache_addremove_sem);
_leave(" = 0 [no caches]");
return 0;
}
/* select a cache in which to store the object */
cache = fscache_select_cache_for_object(cookie->parent);
if (!cache) {
up_read(&fscache_addremove_sem);
fscache_stat(&fscache_n_acquires_no_cache);
_leave(" = -ENOMEDIUM [no cache]");
return -ENOMEDIUM;
}
_debug("cache %s", cache->tag->name);
cookie->flags =
(1 << FSCACHE_COOKIE_LOOKING_UP) |
(1 << FSCACHE_COOKIE_CREATING) |
(1 << FSCACHE_COOKIE_NO_DATA_YET);
/* ask the cache to allocate objects for this cookie and its parent
* chain */
ret = fscache_alloc_object(cache, cookie);
if (ret < 0) {
up_read(&fscache_addremove_sem);
_leave(" = %d", ret);
return ret;
}
/* pass on how big the object we're caching is supposed to be */
cookie->def->get_attr(cookie->netfs_data, &i_size);
spin_lock(&cookie->lock);
if (hlist_empty(&cookie->backing_objects)) {
spin_unlock(&cookie->lock);
goto unavailable;
}
object = hlist_entry(cookie->backing_objects.first,
struct fscache_object, cookie_link);
fscache_set_store_limit(object, i_size);
/* initiate the process of looking up all the objects in the chain
* (done by fscache_initialise_object()) */
fscache_enqueue_object(object);
spin_unlock(&cookie->lock);
/* we may be required to wait for lookup to complete at this point */
if (!fscache_defer_lookup) {
_debug("non-deferred lookup %p", &cookie->flags);
wait_on_bit(&cookie->flags, FSCACHE_COOKIE_LOOKING_UP,
fscache_wait_bit, TASK_UNINTERRUPTIBLE);
_debug("complete");
if (test_bit(FSCACHE_COOKIE_UNAVAILABLE, &cookie->flags))
goto unavailable;
}
up_read(&fscache_addremove_sem);
_leave(" = 0 [deferred]");
return 0;
unavailable:
up_read(&fscache_addremove_sem);
_leave(" = -ENOBUFS");
return -ENOBUFS;
}
/*
* recursively allocate cache object records for a cookie/cache combination
* - caller must be holding the addremove sem
*/
static int fscache_alloc_object(struct fscache_cache *cache,
struct fscache_cookie *cookie)
{
struct fscache_object *object;
struct hlist_node *_n;
int ret;
_enter("%p,%p{%s}", cache, cookie, cookie->def->name);
spin_lock(&cookie->lock);
hlist_for_each_entry(object, _n, &cookie->backing_objects,
cookie_link) {
if (object->cache == cache)
goto object_already_extant;
}
spin_unlock(&cookie->lock);
/* ask the cache to allocate an object (we may end up with duplicate
* objects at this stage, but we sort that out later) */
object = cache->ops->alloc_object(cache, cookie);
if (IS_ERR(object)) {
fscache_stat(&fscache_n_object_no_alloc);
ret = PTR_ERR(object);
goto error;
}
fscache_stat(&fscache_n_object_alloc);
object->debug_id = atomic_inc_return(&fscache_object_debug_id);
_debug("ALLOC OBJ%x: %s {%lx}",
object->debug_id, cookie->def->name, object->events);
ret = fscache_alloc_object(cache, cookie->parent);
if (ret < 0)
goto error_put;
/* only attach if we managed to allocate all we needed, otherwise
* discard the object we just allocated and instead use the one
* attached to the cookie */
if (fscache_attach_object(cookie, object) < 0)
cache->ops->put_object(object);
_leave(" = 0");
return 0;
object_already_extant:
ret = -ENOBUFS;
if (object->state >= FSCACHE_OBJECT_DYING) {
spin_unlock(&cookie->lock);
goto error;
}
spin_unlock(&cookie->lock);
_leave(" = 0 [found]");
return 0;
error_put:
cache->ops->put_object(object);
error:
_leave(" = %d", ret);
return ret;
}
/*
* attach a cache object to a cookie
*/
static int fscache_attach_object(struct fscache_cookie *cookie,
struct fscache_object *object)
{
struct fscache_object *p;
struct fscache_cache *cache = object->cache;
struct hlist_node *_n;
int ret;
_enter("{%s},{OBJ%x}", cookie->def->name, object->debug_id);
spin_lock(&cookie->lock);
/* there may be multiple initial creations of this object, but we only
* want one */
ret = -EEXIST;
hlist_for_each_entry(p, _n, &cookie->backing_objects, cookie_link) {
if (p->cache == object->cache) {
if (p->state >= FSCACHE_OBJECT_DYING)
ret = -ENOBUFS;
goto cant_attach_object;
}
}
/* pin the parent object */
spin_lock_nested(&cookie->parent->lock, 1);
hlist_for_each_entry(p, _n, &cookie->parent->backing_objects,
cookie_link) {
if (p->cache == object->cache) {
if (p->state >= FSCACHE_OBJECT_DYING) {
ret = -ENOBUFS;
spin_unlock(&cookie->parent->lock);
goto cant_attach_object;
}
object->parent = p;
spin_lock(&p->lock);
p->n_children++;
spin_unlock(&p->lock);
break;
}
}
spin_unlock(&cookie->parent->lock);
/* attach to the cache's object list */
if (list_empty(&object->cache_link)) {
spin_lock(&cache->object_list_lock);
list_add(&object->cache_link, &cache->object_list);
spin_unlock(&cache->object_list_lock);
}
/* attach to the cookie */
object->cookie = cookie;
atomic_inc(&cookie->usage);
hlist_add_head(&object->cookie_link, &cookie->backing_objects);
ret = 0;
cant_attach_object:
spin_unlock(&cookie->lock);
_leave(" = %d", ret);
return ret;
}
/*
* update the index entries backing a cookie
*/
void __fscache_update_cookie(struct fscache_cookie *cookie)
{
struct fscache_object *object;
struct hlist_node *_p;
fscache_stat(&fscache_n_updates);
if (!cookie) {
fscache_stat(&fscache_n_updates_null);
_leave(" [no cookie]");
return;
}
_enter("{%s}", cookie->def->name);
BUG_ON(!cookie->def->get_aux);
spin_lock(&cookie->lock);
/* update the index entry on disk in each cache backing this cookie */
hlist_for_each_entry(object, _p,
&cookie->backing_objects, cookie_link) {
fscache_raise_event(object, FSCACHE_OBJECT_EV_UPDATE);
}
spin_unlock(&cookie->lock);
_leave("");
}
EXPORT_SYMBOL(__fscache_update_cookie);
/*
* release a cookie back to the cache
* - the object will be marked as recyclable on disk if retire is true
* - all dependents of this cookie must have already been unregistered
* (indices/files/pages)
*/
void __fscache_relinquish_cookie(struct fscache_cookie *cookie, int retire)
{
struct fscache_cache *cache;
struct fscache_object *object;
unsigned long event;
fscache_stat(&fscache_n_relinquishes);
if (!cookie) {
fscache_stat(&fscache_n_relinquishes_null);
_leave(" [no cookie]");
return;
}
_enter("%p{%s,%p},%d",
cookie, cookie->def->name, cookie->netfs_data, retire);
if (atomic_read(&cookie->n_children) != 0) {
printk(KERN_ERR "FS-Cache: Cookie '%s' still has children\n",
cookie->def->name);
BUG();
}
/* wait for the cookie to finish being instantiated (or to fail) */
if (test_bit(FSCACHE_COOKIE_CREATING, &cookie->flags)) {
fscache_stat(&fscache_n_relinquishes_waitcrt);
wait_on_bit(&cookie->flags, FSCACHE_COOKIE_CREATING,
fscache_wait_bit, TASK_UNINTERRUPTIBLE);
}
event = retire ? FSCACHE_OBJECT_EV_RETIRE : FSCACHE_OBJECT_EV_RELEASE;
/* detach pointers back to the netfs */
spin_lock(&cookie->lock);
cookie->netfs_data = NULL;
cookie->def = NULL;
/* break links with all the active objects */
while (!hlist_empty(&cookie->backing_objects)) {
object = hlist_entry(cookie->backing_objects.first,
struct fscache_object,
cookie_link);
_debug("RELEASE OBJ%x", object->debug_id);
/* detach each cache object from the object cookie */
spin_lock(&object->lock);
hlist_del_init(&object->cookie_link);
cache = object->cache;
object->cookie = NULL;
fscache_raise_event(object, event);
spin_unlock(&object->lock);
if (atomic_dec_and_test(&cookie->usage))
/* the cookie refcount shouldn't be reduced to 0 yet */
BUG();
}
spin_unlock(&cookie->lock);
if (cookie->parent) {
ASSERTCMP(atomic_read(&cookie->parent->usage), >, 0);
ASSERTCMP(atomic_read(&cookie->parent->n_children), >, 0);
atomic_dec(&cookie->parent->n_children);
}
/* finally dispose of the cookie */
ASSERTCMP(atomic_read(&cookie->usage), >, 0);
fscache_cookie_put(cookie);
_leave("");
}
EXPORT_SYMBOL(__fscache_relinquish_cookie);
/*
* destroy a cookie
*/
void __fscache_cookie_put(struct fscache_cookie *cookie)
{
struct fscache_cookie *parent;
_enter("%p", cookie);
for (;;) {
_debug("FREE COOKIE %p", cookie);
parent = cookie->parent;
BUG_ON(!hlist_empty(&cookie->backing_objects));
kmem_cache_free(fscache_cookie_jar, cookie);
if (!parent)
break;
cookie = parent;
BUG_ON(atomic_read(&cookie->usage) <= 0);
if (!atomic_dec_and_test(&cookie->usage))
break;
}
_leave("");
}

144
fs/fscache/fsdef.c Normal file
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/* Filesystem index definition
*
* Copyright (C) 2004-2007 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#define FSCACHE_DEBUG_LEVEL CACHE
#include <linux/module.h>
#include "internal.h"
static uint16_t fscache_fsdef_netfs_get_key(const void *cookie_netfs_data,
void *buffer, uint16_t bufmax);
static uint16_t fscache_fsdef_netfs_get_aux(const void *cookie_netfs_data,
void *buffer, uint16_t bufmax);
static
enum fscache_checkaux fscache_fsdef_netfs_check_aux(void *cookie_netfs_data,
const void *data,
uint16_t datalen);
/*
* The root index is owned by FS-Cache itself.
*
* When a netfs requests caching facilities, FS-Cache will, if one doesn't
* already exist, create an entry in the root index with the key being the name
* of the netfs ("AFS" for example), and the auxiliary data holding the index
* structure version supplied by the netfs:
*
* FSDEF
* |
* +-----------+
* | |
* NFS AFS
* [v=1] [v=1]
*
* If an entry with the appropriate name does already exist, the version is
* compared. If the version is different, the entire subtree from that entry
* will be discarded and a new entry created.
*
* The new entry will be an index, and a cookie referring to it will be passed
* to the netfs. This is then the root handle by which the netfs accesses the
* cache. It can create whatever objects it likes in that index, including
* further indices.
*/
static struct fscache_cookie_def fscache_fsdef_index_def = {
.name = ".FS-Cache",
.type = FSCACHE_COOKIE_TYPE_INDEX,
};
struct fscache_cookie fscache_fsdef_index = {
.usage = ATOMIC_INIT(1),
.lock = __SPIN_LOCK_UNLOCKED(fscache_fsdef_index.lock),
.backing_objects = HLIST_HEAD_INIT,
.def = &fscache_fsdef_index_def,
};
EXPORT_SYMBOL(fscache_fsdef_index);
/*
* Definition of an entry in the root index. Each entry is an index, keyed to
* a specific netfs and only applicable to a particular version of the index
* structure used by that netfs.
*/
struct fscache_cookie_def fscache_fsdef_netfs_def = {
.name = "FSDEF.netfs",
.type = FSCACHE_COOKIE_TYPE_INDEX,
.get_key = fscache_fsdef_netfs_get_key,
.get_aux = fscache_fsdef_netfs_get_aux,
.check_aux = fscache_fsdef_netfs_check_aux,
};
/*
* get the key data for an FSDEF index record - this is the name of the netfs
* for which this entry is created
*/
static uint16_t fscache_fsdef_netfs_get_key(const void *cookie_netfs_data,
void *buffer, uint16_t bufmax)
{
const struct fscache_netfs *netfs = cookie_netfs_data;
unsigned klen;
_enter("{%s.%u},", netfs->name, netfs->version);
klen = strlen(netfs->name);
if (klen > bufmax)
return 0;
memcpy(buffer, netfs->name, klen);
return klen;
}
/*
* get the auxiliary data for an FSDEF index record - this is the index
* structure version number of the netfs for which this version is created
*/
static uint16_t fscache_fsdef_netfs_get_aux(const void *cookie_netfs_data,
void *buffer, uint16_t bufmax)
{
const struct fscache_netfs *netfs = cookie_netfs_data;
unsigned dlen;
_enter("{%s.%u},", netfs->name, netfs->version);
dlen = sizeof(uint32_t);
if (dlen > bufmax)
return 0;
memcpy(buffer, &netfs->version, dlen);
return dlen;
}
/*
* check that the index structure version number stored in the auxiliary data
* matches the one the netfs gave us
*/
static enum fscache_checkaux fscache_fsdef_netfs_check_aux(
void *cookie_netfs_data,
const void *data,
uint16_t datalen)
{
struct fscache_netfs *netfs = cookie_netfs_data;
uint32_t version;
_enter("{%s},,%hu", netfs->name, datalen);
if (datalen != sizeof(version)) {
_leave(" = OBSOLETE [dl=%d v=%zu]", datalen, sizeof(version));
return FSCACHE_CHECKAUX_OBSOLETE;
}
memcpy(&version, data, sizeof(version));
if (version != netfs->version) {
_leave(" = OBSOLETE [ver=%x net=%x]", version, netfs->version);
return FSCACHE_CHECKAUX_OBSOLETE;
}
_leave(" = OKAY");
return FSCACHE_CHECKAUX_OKAY;
}

109
fs/fscache/histogram.c Normal file
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/* FS-Cache latency histogram
*
* Copyright (C) 2008 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public Licence
* as published by the Free Software Foundation; either version
* 2 of the Licence, or (at your option) any later version.
*/
#define FSCACHE_DEBUG_LEVEL THREAD
#include <linux/module.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include "internal.h"
atomic_t fscache_obj_instantiate_histogram[HZ];
atomic_t fscache_objs_histogram[HZ];
atomic_t fscache_ops_histogram[HZ];
atomic_t fscache_retrieval_delay_histogram[HZ];
atomic_t fscache_retrieval_histogram[HZ];
/*
* display the time-taken histogram
*/
static int fscache_histogram_show(struct seq_file *m, void *v)
{
unsigned long index;
unsigned n[5], t;
switch ((unsigned long) v) {
case 1:
seq_puts(m, "JIFS SECS OBJ INST OP RUNS OBJ RUNS "
" RETRV DLY RETRIEVLS\n");
return 0;
case 2:
seq_puts(m, "===== ===== ========= ========= ========="
" ========= =========\n");
return 0;
default:
index = (unsigned long) v - 3;
n[0] = atomic_read(&fscache_obj_instantiate_histogram[index]);
n[1] = atomic_read(&fscache_ops_histogram[index]);
n[2] = atomic_read(&fscache_objs_histogram[index]);
n[3] = atomic_read(&fscache_retrieval_delay_histogram[index]);
n[4] = atomic_read(&fscache_retrieval_histogram[index]);
if (!(n[0] | n[1] | n[2] | n[3] | n[4]))
return 0;
t = (index * 1000) / HZ;
seq_printf(m, "%4lu 0.%03u %9u %9u %9u %9u %9u\n",
index, t, n[0], n[1], n[2], n[3], n[4]);
return 0;
}
}
/*
* set up the iterator to start reading from the first line
*/
static void *fscache_histogram_start(struct seq_file *m, loff_t *_pos)
{
if ((unsigned long long)*_pos >= HZ + 2)
return NULL;
if (*_pos == 0)
*_pos = 1;
return (void *)(unsigned long) *_pos;
}
/*
* move to the next line
*/
static void *fscache_histogram_next(struct seq_file *m, void *v, loff_t *pos)
{
(*pos)++;
return (unsigned long long)*pos > HZ + 2 ?
NULL : (void *)(unsigned long) *pos;
}
/*
* clean up after reading
*/
static void fscache_histogram_stop(struct seq_file *m, void *v)
{
}
static const struct seq_operations fscache_histogram_ops = {
.start = fscache_histogram_start,
.stop = fscache_histogram_stop,
.next = fscache_histogram_next,
.show = fscache_histogram_show,
};
/*
* open "/proc/fs/fscache/histogram" to provide latency data
*/
static int fscache_histogram_open(struct inode *inode, struct file *file)
{
return seq_open(file, &fscache_histogram_ops);
}
const struct file_operations fscache_histogram_fops = {
.owner = THIS_MODULE,
.open = fscache_histogram_open,
.read = seq_read,
.llseek = seq_lseek,
.release = seq_release,
};

380
fs/fscache/internal.h Normal file
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/* Internal definitions for FS-Cache
*
* Copyright (C) 2004-2007 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
/*
* Lock order, in the order in which multiple locks should be obtained:
* - fscache_addremove_sem
* - cookie->lock
* - cookie->parent->lock
* - cache->object_list_lock
* - object->lock
* - object->parent->lock
* - fscache_thread_lock
*
*/
#include <linux/fscache-cache.h>
#include <linux/sched.h>
#define FSCACHE_MIN_THREADS 4
#define FSCACHE_MAX_THREADS 32
/*
* fsc-cache.c
*/
extern struct list_head fscache_cache_list;
extern struct rw_semaphore fscache_addremove_sem;
extern struct fscache_cache *fscache_select_cache_for_object(
struct fscache_cookie *);
/*
* fsc-cookie.c
*/
extern struct kmem_cache *fscache_cookie_jar;
extern void fscache_cookie_init_once(void *);
extern void __fscache_cookie_put(struct fscache_cookie *);
/*
* fsc-fsdef.c
*/
extern struct fscache_cookie fscache_fsdef_index;
extern struct fscache_cookie_def fscache_fsdef_netfs_def;
/*
* fsc-histogram.c
*/
#ifdef CONFIG_FSCACHE_HISTOGRAM
extern atomic_t fscache_obj_instantiate_histogram[HZ];
extern atomic_t fscache_objs_histogram[HZ];
extern atomic_t fscache_ops_histogram[HZ];
extern atomic_t fscache_retrieval_delay_histogram[HZ];
extern atomic_t fscache_retrieval_histogram[HZ];
static inline void fscache_hist(atomic_t histogram[], unsigned long start_jif)
{
unsigned long jif = jiffies - start_jif;
if (jif >= HZ)
jif = HZ - 1;
atomic_inc(&histogram[jif]);
}
extern const struct file_operations fscache_histogram_fops;
#else
#define fscache_hist(hist, start_jif) do {} while (0)
#endif
/*
* fsc-main.c
*/
extern unsigned fscache_defer_lookup;
extern unsigned fscache_defer_create;
extern unsigned fscache_debug;
extern struct kobject *fscache_root;
extern int fscache_wait_bit(void *);
extern int fscache_wait_bit_interruptible(void *);
/*
* fsc-object.c
*/
extern void fscache_withdrawing_object(struct fscache_cache *,
struct fscache_object *);
extern void fscache_enqueue_object(struct fscache_object *);
/*
* fsc-operation.c
*/
extern int fscache_submit_exclusive_op(struct fscache_object *,
struct fscache_operation *);
extern int fscache_submit_op(struct fscache_object *,
struct fscache_operation *);
extern void fscache_abort_object(struct fscache_object *);
extern void fscache_start_operations(struct fscache_object *);
extern void fscache_operation_gc(struct work_struct *);
/*
* fsc-proc.c
*/
#ifdef CONFIG_PROC_FS
extern int __init fscache_proc_init(void);
extern void fscache_proc_cleanup(void);
#else
#define fscache_proc_init() (0)
#define fscache_proc_cleanup() do {} while (0)
#endif
/*
* fsc-stats.c
*/
#ifdef CONFIG_FSCACHE_STATS
extern atomic_t fscache_n_ops_processed[FSCACHE_MAX_THREADS];
extern atomic_t fscache_n_objs_processed[FSCACHE_MAX_THREADS];
extern atomic_t fscache_n_op_pend;
extern atomic_t fscache_n_op_run;
extern atomic_t fscache_n_op_enqueue;
extern atomic_t fscache_n_op_deferred_release;
extern atomic_t fscache_n_op_release;
extern atomic_t fscache_n_op_gc;
extern atomic_t fscache_n_attr_changed;
extern atomic_t fscache_n_attr_changed_ok;
extern atomic_t fscache_n_attr_changed_nobufs;
extern atomic_t fscache_n_attr_changed_nomem;
extern atomic_t fscache_n_attr_changed_calls;
extern atomic_t fscache_n_allocs;
extern atomic_t fscache_n_allocs_ok;
extern atomic_t fscache_n_allocs_wait;
extern atomic_t fscache_n_allocs_nobufs;
extern atomic_t fscache_n_alloc_ops;
extern atomic_t fscache_n_alloc_op_waits;
extern atomic_t fscache_n_retrievals;
extern atomic_t fscache_n_retrievals_ok;
extern atomic_t fscache_n_retrievals_wait;
extern atomic_t fscache_n_retrievals_nodata;
extern atomic_t fscache_n_retrievals_nobufs;
extern atomic_t fscache_n_retrievals_intr;
extern atomic_t fscache_n_retrievals_nomem;
extern atomic_t fscache_n_retrieval_ops;
extern atomic_t fscache_n_retrieval_op_waits;
extern atomic_t fscache_n_stores;
extern atomic_t fscache_n_stores_ok;
extern atomic_t fscache_n_stores_again;
extern atomic_t fscache_n_stores_nobufs;
extern atomic_t fscache_n_stores_oom;
extern atomic_t fscache_n_store_ops;
extern atomic_t fscache_n_store_calls;
extern atomic_t fscache_n_marks;
extern atomic_t fscache_n_uncaches;
extern atomic_t fscache_n_acquires;
extern atomic_t fscache_n_acquires_null;
extern atomic_t fscache_n_acquires_no_cache;
extern atomic_t fscache_n_acquires_ok;
extern atomic_t fscache_n_acquires_nobufs;
extern atomic_t fscache_n_acquires_oom;
extern atomic_t fscache_n_updates;
extern atomic_t fscache_n_updates_null;
extern atomic_t fscache_n_updates_run;
extern atomic_t fscache_n_relinquishes;
extern atomic_t fscache_n_relinquishes_null;
extern atomic_t fscache_n_relinquishes_waitcrt;
extern atomic_t fscache_n_cookie_index;
extern atomic_t fscache_n_cookie_data;
extern atomic_t fscache_n_cookie_special;
extern atomic_t fscache_n_object_alloc;
extern atomic_t fscache_n_object_no_alloc;
extern atomic_t fscache_n_object_lookups;
extern atomic_t fscache_n_object_lookups_negative;
extern atomic_t fscache_n_object_lookups_positive;
extern atomic_t fscache_n_object_created;
extern atomic_t fscache_n_object_avail;
extern atomic_t fscache_n_object_dead;
extern atomic_t fscache_n_checkaux_none;
extern atomic_t fscache_n_checkaux_okay;
extern atomic_t fscache_n_checkaux_update;
extern atomic_t fscache_n_checkaux_obsolete;
static inline void fscache_stat(atomic_t *stat)
{
atomic_inc(stat);
}
extern const struct file_operations fscache_stats_fops;
#else
#define fscache_stat(stat) do {} while (0)
#endif
/*
* raise an event on an object
* - if the event is not masked for that object, then the object is
* queued for attention by the thread pool.
*/
static inline void fscache_raise_event(struct fscache_object *object,
unsigned event)
{
if (!test_and_set_bit(event, &object->events) &&
test_bit(event, &object->event_mask))
fscache_enqueue_object(object);
}
/*
* drop a reference to a cookie
*/
static inline void fscache_cookie_put(struct fscache_cookie *cookie)
{
BUG_ON(atomic_read(&cookie->usage) <= 0);
if (atomic_dec_and_test(&cookie->usage))
__fscache_cookie_put(cookie);
}
/*
* get an extra reference to a netfs retrieval context
*/
static inline
void *fscache_get_context(struct fscache_cookie *cookie, void *context)
{
if (cookie->def->get_context)
cookie->def->get_context(cookie->netfs_data, context);
return context;
}
/*
* release a reference to a netfs retrieval context
*/
static inline
void fscache_put_context(struct fscache_cookie *cookie, void *context)
{
if (cookie->def->put_context)
cookie->def->put_context(cookie->netfs_data, context);
}
/*****************************************************************************/
/*
* debug tracing
*/
#define dbgprintk(FMT, ...) \
printk(KERN_DEBUG "[%-6.6s] "FMT"\n", current->comm, ##__VA_ARGS__)
/* make sure we maintain the format strings, even when debugging is disabled */
static inline __attribute__((format(printf, 1, 2)))
void _dbprintk(const char *fmt, ...)
{
}
#define kenter(FMT, ...) dbgprintk("==> %s("FMT")", __func__, ##__VA_ARGS__)
#define kleave(FMT, ...) dbgprintk("<== %s()"FMT"", __func__, ##__VA_ARGS__)
#define kdebug(FMT, ...) dbgprintk(FMT, ##__VA_ARGS__)
#define kjournal(FMT, ...) _dbprintk(FMT, ##__VA_ARGS__)
#ifdef __KDEBUG
#define _enter(FMT, ...) kenter(FMT, ##__VA_ARGS__)
#define _leave(FMT, ...) kleave(FMT, ##__VA_ARGS__)
#define _debug(FMT, ...) kdebug(FMT, ##__VA_ARGS__)
#elif defined(CONFIG_FSCACHE_DEBUG)
#define _enter(FMT, ...) \
do { \
if (__do_kdebug(ENTER)) \
kenter(FMT, ##__VA_ARGS__); \
} while (0)
#define _leave(FMT, ...) \
do { \
if (__do_kdebug(LEAVE)) \
kleave(FMT, ##__VA_ARGS__); \
} while (0)
#define _debug(FMT, ...) \
do { \
if (__do_kdebug(DEBUG)) \
kdebug(FMT, ##__VA_ARGS__); \
} while (0)
#else
#define _enter(FMT, ...) _dbprintk("==> %s("FMT")", __func__, ##__VA_ARGS__)
#define _leave(FMT, ...) _dbprintk("<== %s()"FMT"", __func__, ##__VA_ARGS__)
#define _debug(FMT, ...) _dbprintk(FMT, ##__VA_ARGS__)
#endif
/*
* determine whether a particular optional debugging point should be logged
* - we need to go through three steps to persuade cpp to correctly join the
* shorthand in FSCACHE_DEBUG_LEVEL with its prefix
*/
#define ____do_kdebug(LEVEL, POINT) \
unlikely((fscache_debug & \
(FSCACHE_POINT_##POINT << (FSCACHE_DEBUG_ ## LEVEL * 3))))
#define ___do_kdebug(LEVEL, POINT) \
____do_kdebug(LEVEL, POINT)
#define __do_kdebug(POINT) \
___do_kdebug(FSCACHE_DEBUG_LEVEL, POINT)
#define FSCACHE_DEBUG_CACHE 0
#define FSCACHE_DEBUG_COOKIE 1
#define FSCACHE_DEBUG_PAGE 2
#define FSCACHE_DEBUG_OPERATION 3
#define FSCACHE_POINT_ENTER 1
#define FSCACHE_POINT_LEAVE 2
#define FSCACHE_POINT_DEBUG 4
#ifndef FSCACHE_DEBUG_LEVEL
#define FSCACHE_DEBUG_LEVEL CACHE
#endif
/*
* assertions
*/
#if 1 /* defined(__KDEBUGALL) */
#define ASSERT(X) \
do { \
if (unlikely(!(X))) { \
printk(KERN_ERR "\n"); \
printk(KERN_ERR "FS-Cache: Assertion failed\n"); \
BUG(); \
} \
} while (0)
#define ASSERTCMP(X, OP, Y) \
do { \
if (unlikely(!((X) OP (Y)))) { \
printk(KERN_ERR "\n"); \
printk(KERN_ERR "FS-Cache: Assertion failed\n"); \
printk(KERN_ERR "%lx " #OP " %lx is false\n", \
(unsigned long)(X), (unsigned long)(Y)); \
BUG(); \
} \
} while (0)
#define ASSERTIF(C, X) \
do { \
if (unlikely((C) && !(X))) { \
printk(KERN_ERR "\n"); \
printk(KERN_ERR "FS-Cache: Assertion failed\n"); \
BUG(); \
} \
} while (0)
#define ASSERTIFCMP(C, X, OP, Y) \
do { \
if (unlikely((C) && !((X) OP (Y)))) { \
printk(KERN_ERR "\n"); \
printk(KERN_ERR "FS-Cache: Assertion failed\n"); \
printk(KERN_ERR "%lx " #OP " %lx is false\n", \
(unsigned long)(X), (unsigned long)(Y)); \
BUG(); \
} \
} while (0)
#else
#define ASSERT(X) do {} while (0)
#define ASSERTCMP(X, OP, Y) do {} while (0)
#define ASSERTIF(C, X) do {} while (0)
#define ASSERTIFCMP(C, X, OP, Y) do {} while (0)
#endif /* assert or not */

124
fs/fscache/main.c Normal file
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@ -0,0 +1,124 @@
/* General filesystem local caching manager
*
* Copyright (C) 2004-2007 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#define FSCACHE_DEBUG_LEVEL CACHE
#include <linux/module.h>
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/completion.h>
#include <linux/slab.h>
#include "internal.h"
MODULE_DESCRIPTION("FS Cache Manager");
MODULE_AUTHOR("Red Hat, Inc.");
MODULE_LICENSE("GPL");
unsigned fscache_defer_lookup = 1;
module_param_named(defer_lookup, fscache_defer_lookup, uint,
S_IWUSR | S_IRUGO);
MODULE_PARM_DESC(fscache_defer_lookup,
"Defer cookie lookup to background thread");
unsigned fscache_defer_create = 1;
module_param_named(defer_create, fscache_defer_create, uint,
S_IWUSR | S_IRUGO);
MODULE_PARM_DESC(fscache_defer_create,
"Defer cookie creation to background thread");
unsigned fscache_debug;
module_param_named(debug, fscache_debug, uint,
S_IWUSR | S_IRUGO);
MODULE_PARM_DESC(fscache_debug,
"FS-Cache debugging mask");
struct kobject *fscache_root;
/*
* initialise the fs caching module
*/
static int __init fscache_init(void)
{
int ret;
ret = slow_work_register_user();
if (ret < 0)
goto error_slow_work;
ret = fscache_proc_init();
if (ret < 0)
goto error_proc;
fscache_cookie_jar = kmem_cache_create("fscache_cookie_jar",
sizeof(struct fscache_cookie),
0,
0,
fscache_cookie_init_once);
if (!fscache_cookie_jar) {
printk(KERN_NOTICE
"FS-Cache: Failed to allocate a cookie jar\n");
ret = -ENOMEM;
goto error_cookie_jar;
}
fscache_root = kobject_create_and_add("fscache", kernel_kobj);
if (!fscache_root)
goto error_kobj;
printk(KERN_NOTICE "FS-Cache: Loaded\n");
return 0;
error_kobj:
kmem_cache_destroy(fscache_cookie_jar);
error_cookie_jar:
fscache_proc_cleanup();
error_proc:
slow_work_unregister_user();
error_slow_work:
return ret;
}
fs_initcall(fscache_init);
/*
* clean up on module removal
*/
static void __exit fscache_exit(void)
{
_enter("");
kobject_put(fscache_root);
kmem_cache_destroy(fscache_cookie_jar);
fscache_proc_cleanup();
slow_work_unregister_user();
printk(KERN_NOTICE "FS-Cache: Unloaded\n");
}
module_exit(fscache_exit);
/*
* wait_on_bit() sleep function for uninterruptible waiting
*/
int fscache_wait_bit(void *flags)
{
schedule();
return 0;
}
EXPORT_SYMBOL(fscache_wait_bit);
/*
* wait_on_bit() sleep function for interruptible waiting
*/
int fscache_wait_bit_interruptible(void *flags)
{
schedule();
return signal_pending(current);
}
EXPORT_SYMBOL(fscache_wait_bit_interruptible);

103
fs/fscache/netfs.c Normal file
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@ -0,0 +1,103 @@
/* FS-Cache netfs (client) registration
*
* Copyright (C) 2008 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public Licence
* as published by the Free Software Foundation; either version
* 2 of the Licence, or (at your option) any later version.
*/
#define FSCACHE_DEBUG_LEVEL COOKIE
#include <linux/module.h>
#include <linux/slab.h>
#include "internal.h"
static LIST_HEAD(fscache_netfs_list);
/*
* register a network filesystem for caching
*/
int __fscache_register_netfs(struct fscache_netfs *netfs)
{
struct fscache_netfs *ptr;
int ret;
_enter("{%s}", netfs->name);
INIT_LIST_HEAD(&netfs->link);
/* allocate a cookie for the primary index */
netfs->primary_index =
kmem_cache_zalloc(fscache_cookie_jar, GFP_KERNEL);
if (!netfs->primary_index) {
_leave(" = -ENOMEM");
return -ENOMEM;
}
/* initialise the primary index cookie */
atomic_set(&netfs->primary_index->usage, 1);
atomic_set(&netfs->primary_index->n_children, 0);
netfs->primary_index->def = &fscache_fsdef_netfs_def;
netfs->primary_index->parent = &fscache_fsdef_index;
netfs->primary_index->netfs_data = netfs;
atomic_inc(&netfs->primary_index->parent->usage);
atomic_inc(&netfs->primary_index->parent->n_children);
spin_lock_init(&netfs->primary_index->lock);
INIT_HLIST_HEAD(&netfs->primary_index->backing_objects);
/* check the netfs type is not already present */
down_write(&fscache_addremove_sem);
ret = -EEXIST;
list_for_each_entry(ptr, &fscache_netfs_list, link) {
if (strcmp(ptr->name, netfs->name) == 0)
goto already_registered;
}
list_add(&netfs->link, &fscache_netfs_list);
ret = 0;
printk(KERN_NOTICE "FS-Cache: Netfs '%s' registered for caching\n",
netfs->name);
already_registered:
up_write(&fscache_addremove_sem);
if (ret < 0) {
netfs->primary_index->parent = NULL;
__fscache_cookie_put(netfs->primary_index);
netfs->primary_index = NULL;
}
_leave(" = %d", ret);
return ret;
}
EXPORT_SYMBOL(__fscache_register_netfs);
/*
* unregister a network filesystem from the cache
* - all cookies must have been released first
*/
void __fscache_unregister_netfs(struct fscache_netfs *netfs)
{
_enter("{%s.%u}", netfs->name, netfs->version);
down_write(&fscache_addremove_sem);
list_del(&netfs->link);
fscache_relinquish_cookie(netfs->primary_index, 0);
up_write(&fscache_addremove_sem);
printk(KERN_NOTICE "FS-Cache: Netfs '%s' unregistered from caching\n",
netfs->name);
_leave("");
}
EXPORT_SYMBOL(__fscache_unregister_netfs);

810
fs/fscache/object.c Normal file
View File

@ -0,0 +1,810 @@
/* FS-Cache object state machine handler
*
* Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*
* See Documentation/filesystems/caching/object.txt for a description of the
* object state machine and the in-kernel representations.
*/
#define FSCACHE_DEBUG_LEVEL COOKIE
#include <linux/module.h>
#include "internal.h"
const char *fscache_object_states[] = {
[FSCACHE_OBJECT_INIT] = "OBJECT_INIT",
[FSCACHE_OBJECT_LOOKING_UP] = "OBJECT_LOOKING_UP",
[FSCACHE_OBJECT_CREATING] = "OBJECT_CREATING",
[FSCACHE_OBJECT_AVAILABLE] = "OBJECT_AVAILABLE",
[FSCACHE_OBJECT_ACTIVE] = "OBJECT_ACTIVE",
[FSCACHE_OBJECT_UPDATING] = "OBJECT_UPDATING",
[FSCACHE_OBJECT_DYING] = "OBJECT_DYING",
[FSCACHE_OBJECT_LC_DYING] = "OBJECT_LC_DYING",
[FSCACHE_OBJECT_ABORT_INIT] = "OBJECT_ABORT_INIT",
[FSCACHE_OBJECT_RELEASING] = "OBJECT_RELEASING",
[FSCACHE_OBJECT_RECYCLING] = "OBJECT_RECYCLING",
[FSCACHE_OBJECT_WITHDRAWING] = "OBJECT_WITHDRAWING",
[FSCACHE_OBJECT_DEAD] = "OBJECT_DEAD",
};
EXPORT_SYMBOL(fscache_object_states);
static void fscache_object_slow_work_put_ref(struct slow_work *);
static int fscache_object_slow_work_get_ref(struct slow_work *);
static void fscache_object_slow_work_execute(struct slow_work *);
static void fscache_initialise_object(struct fscache_object *);
static void fscache_lookup_object(struct fscache_object *);
static void fscache_object_available(struct fscache_object *);
static void fscache_release_object(struct fscache_object *);
static void fscache_withdraw_object(struct fscache_object *);
static void fscache_enqueue_dependents(struct fscache_object *);
static void fscache_dequeue_object(struct fscache_object *);
const struct slow_work_ops fscache_object_slow_work_ops = {
.get_ref = fscache_object_slow_work_get_ref,
.put_ref = fscache_object_slow_work_put_ref,
.execute = fscache_object_slow_work_execute,
};
EXPORT_SYMBOL(fscache_object_slow_work_ops);
/*
* we need to notify the parent when an op completes that we had outstanding
* upon it
*/
static inline void fscache_done_parent_op(struct fscache_object *object)
{
struct fscache_object *parent = object->parent;
_enter("OBJ%x {OBJ%x,%x}",
object->debug_id, parent->debug_id, parent->n_ops);
spin_lock_nested(&parent->lock, 1);
parent->n_ops--;
parent->n_obj_ops--;
if (parent->n_ops == 0)
fscache_raise_event(parent, FSCACHE_OBJECT_EV_CLEARED);
spin_unlock(&parent->lock);
}
/*
* process events that have been sent to an object's state machine
* - initiates parent lookup
* - does object lookup
* - does object creation
* - does object recycling and retirement
* - does object withdrawal
*/
static void fscache_object_state_machine(struct fscache_object *object)
{
enum fscache_object_state new_state;
ASSERT(object != NULL);
_enter("{OBJ%x,%s,%lx}",
object->debug_id, fscache_object_states[object->state],
object->events);
switch (object->state) {
/* wait for the parent object to become ready */
case FSCACHE_OBJECT_INIT:
object->event_mask =
ULONG_MAX & ~(1 << FSCACHE_OBJECT_EV_CLEARED);
fscache_initialise_object(object);
goto done;
/* look up the object metadata on disk */
case FSCACHE_OBJECT_LOOKING_UP:
fscache_lookup_object(object);
goto lookup_transit;
/* create the object metadata on disk */
case FSCACHE_OBJECT_CREATING:
fscache_lookup_object(object);
goto lookup_transit;
/* handle an object becoming available; start pending
* operations and queue dependent operations for processing */
case FSCACHE_OBJECT_AVAILABLE:
fscache_object_available(object);
goto active_transit;
/* normal running state */
case FSCACHE_OBJECT_ACTIVE:
goto active_transit;
/* update the object metadata on disk */
case FSCACHE_OBJECT_UPDATING:
clear_bit(FSCACHE_OBJECT_EV_UPDATE, &object->events);
fscache_stat(&fscache_n_updates_run);
object->cache->ops->update_object(object);
goto active_transit;
/* handle an object dying during lookup or creation */
case FSCACHE_OBJECT_LC_DYING:
object->event_mask &= ~(1 << FSCACHE_OBJECT_EV_UPDATE);
object->cache->ops->lookup_complete(object);
spin_lock(&object->lock);
object->state = FSCACHE_OBJECT_DYING;
if (test_and_clear_bit(FSCACHE_COOKIE_CREATING,
&object->cookie->flags))
wake_up_bit(&object->cookie->flags,
FSCACHE_COOKIE_CREATING);
spin_unlock(&object->lock);
fscache_done_parent_op(object);
/* wait for completion of all active operations on this object
* and the death of all child objects of this object */
case FSCACHE_OBJECT_DYING:
dying:
clear_bit(FSCACHE_OBJECT_EV_CLEARED, &object->events);
spin_lock(&object->lock);
_debug("dying OBJ%x {%d,%d}",
object->debug_id, object->n_ops, object->n_children);
if (object->n_ops == 0 && object->n_children == 0) {
object->event_mask &=
~(1 << FSCACHE_OBJECT_EV_CLEARED);
object->event_mask |=
(1 << FSCACHE_OBJECT_EV_WITHDRAW) |
(1 << FSCACHE_OBJECT_EV_RETIRE) |
(1 << FSCACHE_OBJECT_EV_RELEASE) |
(1 << FSCACHE_OBJECT_EV_ERROR);
} else {
object->event_mask &=
~((1 << FSCACHE_OBJECT_EV_WITHDRAW) |
(1 << FSCACHE_OBJECT_EV_RETIRE) |
(1 << FSCACHE_OBJECT_EV_RELEASE) |
(1 << FSCACHE_OBJECT_EV_ERROR));
object->event_mask |=
1 << FSCACHE_OBJECT_EV_CLEARED;
}
spin_unlock(&object->lock);
fscache_enqueue_dependents(object);
goto terminal_transit;
/* handle an abort during initialisation */
case FSCACHE_OBJECT_ABORT_INIT:
_debug("handle abort init %lx", object->events);
object->event_mask &= ~(1 << FSCACHE_OBJECT_EV_UPDATE);
spin_lock(&object->lock);
fscache_dequeue_object(object);
object->state = FSCACHE_OBJECT_DYING;
if (test_and_clear_bit(FSCACHE_COOKIE_CREATING,
&object->cookie->flags))
wake_up_bit(&object->cookie->flags,
FSCACHE_COOKIE_CREATING);
spin_unlock(&object->lock);
goto dying;
/* handle the netfs releasing an object and possibly marking it
* obsolete too */
case FSCACHE_OBJECT_RELEASING:
case FSCACHE_OBJECT_RECYCLING:
object->event_mask &=
~((1 << FSCACHE_OBJECT_EV_WITHDRAW) |
(1 << FSCACHE_OBJECT_EV_RETIRE) |
(1 << FSCACHE_OBJECT_EV_RELEASE) |
(1 << FSCACHE_OBJECT_EV_ERROR));
fscache_release_object(object);
spin_lock(&object->lock);
object->state = FSCACHE_OBJECT_DEAD;
spin_unlock(&object->lock);
fscache_stat(&fscache_n_object_dead);
goto terminal_transit;
/* handle the parent cache of this object being withdrawn from
* active service */
case FSCACHE_OBJECT_WITHDRAWING:
object->event_mask &=
~((1 << FSCACHE_OBJECT_EV_WITHDRAW) |
(1 << FSCACHE_OBJECT_EV_RETIRE) |
(1 << FSCACHE_OBJECT_EV_RELEASE) |
(1 << FSCACHE_OBJECT_EV_ERROR));
fscache_withdraw_object(object);
spin_lock(&object->lock);
object->state = FSCACHE_OBJECT_DEAD;
spin_unlock(&object->lock);
fscache_stat(&fscache_n_object_dead);
goto terminal_transit;
/* complain about the object being woken up once it is
* deceased */
case FSCACHE_OBJECT_DEAD:
printk(KERN_ERR "FS-Cache:"
" Unexpected event in dead state %lx\n",
object->events & object->event_mask);
BUG();
default:
printk(KERN_ERR "FS-Cache: Unknown object state %u\n",
object->state);
BUG();
}
/* determine the transition from a lookup state */
lookup_transit:
switch (fls(object->events & object->event_mask) - 1) {
case FSCACHE_OBJECT_EV_WITHDRAW:
case FSCACHE_OBJECT_EV_RETIRE:
case FSCACHE_OBJECT_EV_RELEASE:
case FSCACHE_OBJECT_EV_ERROR:
new_state = FSCACHE_OBJECT_LC_DYING;
goto change_state;
case FSCACHE_OBJECT_EV_REQUEUE:
goto done;
case -1:
goto done; /* sleep until event */
default:
goto unsupported_event;
}
/* determine the transition from an active state */
active_transit:
switch (fls(object->events & object->event_mask) - 1) {
case FSCACHE_OBJECT_EV_WITHDRAW:
case FSCACHE_OBJECT_EV_RETIRE:
case FSCACHE_OBJECT_EV_RELEASE:
case FSCACHE_OBJECT_EV_ERROR:
new_state = FSCACHE_OBJECT_DYING;
goto change_state;
case FSCACHE_OBJECT_EV_UPDATE:
new_state = FSCACHE_OBJECT_UPDATING;
goto change_state;
case -1:
new_state = FSCACHE_OBJECT_ACTIVE;
goto change_state; /* sleep until event */
default:
goto unsupported_event;
}
/* determine the transition from a terminal state */
terminal_transit:
switch (fls(object->events & object->event_mask) - 1) {
case FSCACHE_OBJECT_EV_WITHDRAW:
new_state = FSCACHE_OBJECT_WITHDRAWING;
goto change_state;
case FSCACHE_OBJECT_EV_RETIRE:
new_state = FSCACHE_OBJECT_RECYCLING;
goto change_state;
case FSCACHE_OBJECT_EV_RELEASE:
new_state = FSCACHE_OBJECT_RELEASING;
goto change_state;
case FSCACHE_OBJECT_EV_ERROR:
new_state = FSCACHE_OBJECT_WITHDRAWING;
goto change_state;
case FSCACHE_OBJECT_EV_CLEARED:
new_state = FSCACHE_OBJECT_DYING;
goto change_state;
case -1:
goto done; /* sleep until event */
default:
goto unsupported_event;
}
change_state:
spin_lock(&object->lock);
object->state = new_state;
spin_unlock(&object->lock);
done:
_leave(" [->%s]", fscache_object_states[object->state]);
return;
unsupported_event:
printk(KERN_ERR "FS-Cache:"
" Unsupported event %lx [mask %lx] in state %s\n",
object->events, object->event_mask,
fscache_object_states[object->state]);
BUG();
}
/*
* execute an object
*/
static void fscache_object_slow_work_execute(struct slow_work *work)
{
struct fscache_object *object =
container_of(work, struct fscache_object, work);
unsigned long start;
_enter("{OBJ%x}", object->debug_id);
clear_bit(FSCACHE_OBJECT_EV_REQUEUE, &object->events);
start = jiffies;
fscache_object_state_machine(object);
fscache_hist(fscache_objs_histogram, start);
if (object->events & object->event_mask)
fscache_enqueue_object(object);
}
/*
* initialise an object
* - check the specified object's parent to see if we can make use of it
* immediately to do a creation
* - we may need to start the process of creating a parent and we need to wait
* for the parent's lookup and creation to complete if it's not there yet
* - an object's cookie is pinned until we clear FSCACHE_COOKIE_CREATING on the
* leaf-most cookies of the object and all its children
*/
static void fscache_initialise_object(struct fscache_object *object)
{
struct fscache_object *parent;
_enter("");
ASSERT(object->cookie != NULL);
ASSERT(object->cookie->parent != NULL);
ASSERT(list_empty(&object->work.link));
if (object->events & ((1 << FSCACHE_OBJECT_EV_ERROR) |
(1 << FSCACHE_OBJECT_EV_RELEASE) |
(1 << FSCACHE_OBJECT_EV_RETIRE) |
(1 << FSCACHE_OBJECT_EV_WITHDRAW))) {
_debug("abort init %lx", object->events);
spin_lock(&object->lock);
object->state = FSCACHE_OBJECT_ABORT_INIT;
spin_unlock(&object->lock);
return;
}
spin_lock(&object->cookie->lock);
spin_lock_nested(&object->cookie->parent->lock, 1);
parent = object->parent;
if (!parent) {
_debug("no parent");
set_bit(FSCACHE_OBJECT_EV_WITHDRAW, &object->events);
} else {
spin_lock(&object->lock);
spin_lock_nested(&parent->lock, 1);
_debug("parent %s", fscache_object_states[parent->state]);
if (parent->state >= FSCACHE_OBJECT_DYING) {
_debug("bad parent");
set_bit(FSCACHE_OBJECT_EV_WITHDRAW, &object->events);
} else if (parent->state < FSCACHE_OBJECT_AVAILABLE) {
_debug("wait");
/* we may get woken up in this state by child objects
* binding on to us, so we need to make sure we don't
* add ourself to the list multiple times */
if (list_empty(&object->dep_link)) {
object->cache->ops->grab_object(object);
list_add(&object->dep_link,
&parent->dependents);
/* fscache_acquire_non_index_cookie() uses this
* to wake the chain up */
if (parent->state == FSCACHE_OBJECT_INIT)
fscache_enqueue_object(parent);
}
} else {
_debug("go");
parent->n_ops++;
parent->n_obj_ops++;
object->lookup_jif = jiffies;
object->state = FSCACHE_OBJECT_LOOKING_UP;
set_bit(FSCACHE_OBJECT_EV_REQUEUE, &object->events);
}
spin_unlock(&parent->lock);
spin_unlock(&object->lock);
}
spin_unlock(&object->cookie->parent->lock);
spin_unlock(&object->cookie->lock);
_leave("");
}
/*
* look an object up in the cache from which it was allocated
* - we hold an "access lock" on the parent object, so the parent object cannot
* be withdrawn by either party till we've finished
* - an object's cookie is pinned until we clear FSCACHE_COOKIE_CREATING on the
* leaf-most cookies of the object and all its children
*/
static void fscache_lookup_object(struct fscache_object *object)
{
struct fscache_cookie *cookie = object->cookie;
struct fscache_object *parent;
_enter("");
parent = object->parent;
ASSERT(parent != NULL);
ASSERTCMP(parent->n_ops, >, 0);
ASSERTCMP(parent->n_obj_ops, >, 0);
/* make sure the parent is still available */
ASSERTCMP(parent->state, >=, FSCACHE_OBJECT_AVAILABLE);
if (parent->state >= FSCACHE_OBJECT_DYING ||
test_bit(FSCACHE_IOERROR, &object->cache->flags)) {
_debug("unavailable");
set_bit(FSCACHE_OBJECT_EV_WITHDRAW, &object->events);
_leave("");
return;
}
_debug("LOOKUP \"%s/%s\" in \"%s\"",
parent->cookie->def->name, cookie->def->name,
object->cache->tag->name);
fscache_stat(&fscache_n_object_lookups);
object->cache->ops->lookup_object(object);
if (test_bit(FSCACHE_OBJECT_EV_ERROR, &object->events))
set_bit(FSCACHE_COOKIE_UNAVAILABLE, &cookie->flags);
_leave("");
}
/**
* fscache_object_lookup_negative - Note negative cookie lookup
* @object: Object pointing to cookie to mark
*
* Note negative lookup, permitting those waiting to read data from an already
* existing backing object to continue as there's no data for them to read.
*/
void fscache_object_lookup_negative(struct fscache_object *object)
{
struct fscache_cookie *cookie = object->cookie;
_enter("{OBJ%x,%s}",
object->debug_id, fscache_object_states[object->state]);
spin_lock(&object->lock);
if (object->state == FSCACHE_OBJECT_LOOKING_UP) {
fscache_stat(&fscache_n_object_lookups_negative);
/* transit here to allow write requests to begin stacking up
* and read requests to begin returning ENODATA */
object->state = FSCACHE_OBJECT_CREATING;
spin_unlock(&object->lock);
set_bit(FSCACHE_COOKIE_PENDING_FILL, &cookie->flags);
set_bit(FSCACHE_COOKIE_NO_DATA_YET, &cookie->flags);
_debug("wake up lookup %p", &cookie->flags);
smp_mb__before_clear_bit();
clear_bit(FSCACHE_COOKIE_LOOKING_UP, &cookie->flags);
smp_mb__after_clear_bit();
wake_up_bit(&cookie->flags, FSCACHE_COOKIE_LOOKING_UP);
set_bit(FSCACHE_OBJECT_EV_REQUEUE, &object->events);
} else {
ASSERTCMP(object->state, ==, FSCACHE_OBJECT_CREATING);
spin_unlock(&object->lock);
}
_leave("");
}
EXPORT_SYMBOL(fscache_object_lookup_negative);
/**
* fscache_obtained_object - Note successful object lookup or creation
* @object: Object pointing to cookie to mark
*
* Note successful lookup and/or creation, permitting those waiting to write
* data to a backing object to continue.
*
* Note that after calling this, an object's cookie may be relinquished by the
* netfs, and so must be accessed with object lock held.
*/
void fscache_obtained_object(struct fscache_object *object)
{
struct fscache_cookie *cookie = object->cookie;
_enter("{OBJ%x,%s}",
object->debug_id, fscache_object_states[object->state]);
/* if we were still looking up, then we must have a positive lookup
* result, in which case there may be data available */
spin_lock(&object->lock);
if (object->state == FSCACHE_OBJECT_LOOKING_UP) {
fscache_stat(&fscache_n_object_lookups_positive);
clear_bit(FSCACHE_COOKIE_NO_DATA_YET, &cookie->flags);
object->state = FSCACHE_OBJECT_AVAILABLE;
spin_unlock(&object->lock);
smp_mb__before_clear_bit();
clear_bit(FSCACHE_COOKIE_LOOKING_UP, &cookie->flags);
smp_mb__after_clear_bit();
wake_up_bit(&cookie->flags, FSCACHE_COOKIE_LOOKING_UP);
set_bit(FSCACHE_OBJECT_EV_REQUEUE, &object->events);
} else {
ASSERTCMP(object->state, ==, FSCACHE_OBJECT_CREATING);
fscache_stat(&fscache_n_object_created);
object->state = FSCACHE_OBJECT_AVAILABLE;
spin_unlock(&object->lock);
set_bit(FSCACHE_OBJECT_EV_REQUEUE, &object->events);
smp_wmb();
}
if (test_and_clear_bit(FSCACHE_COOKIE_CREATING, &cookie->flags))
wake_up_bit(&cookie->flags, FSCACHE_COOKIE_CREATING);
_leave("");
}
EXPORT_SYMBOL(fscache_obtained_object);
/*
* handle an object that has just become available
*/
static void fscache_object_available(struct fscache_object *object)
{
_enter("{OBJ%x}", object->debug_id);
spin_lock(&object->lock);
if (test_and_clear_bit(FSCACHE_COOKIE_CREATING, &object->cookie->flags))
wake_up_bit(&object->cookie->flags, FSCACHE_COOKIE_CREATING);
fscache_done_parent_op(object);
if (object->n_in_progress == 0) {
if (object->n_ops > 0) {
ASSERTCMP(object->n_ops, >=, object->n_obj_ops);
ASSERTIF(object->n_ops > object->n_obj_ops,
!list_empty(&object->pending_ops));
fscache_start_operations(object);
} else {
ASSERT(list_empty(&object->pending_ops));
}
}
spin_unlock(&object->lock);
object->cache->ops->lookup_complete(object);
fscache_enqueue_dependents(object);
fscache_hist(fscache_obj_instantiate_histogram, object->lookup_jif);
fscache_stat(&fscache_n_object_avail);
_leave("");
}
/*
* drop an object's attachments
*/
static void fscache_drop_object(struct fscache_object *object)
{
struct fscache_object *parent = object->parent;
struct fscache_cache *cache = object->cache;
_enter("{OBJ%x,%d}", object->debug_id, object->n_children);
spin_lock(&cache->object_list_lock);
list_del_init(&object->cache_link);
spin_unlock(&cache->object_list_lock);
cache->ops->drop_object(object);
if (parent) {
_debug("release parent OBJ%x {%d}",
parent->debug_id, parent->n_children);
spin_lock(&parent->lock);
parent->n_children--;
if (parent->n_children == 0)
fscache_raise_event(parent, FSCACHE_OBJECT_EV_CLEARED);
spin_unlock(&parent->lock);
object->parent = NULL;
}
/* this just shifts the object release to the slow work processor */
object->cache->ops->put_object(object);
_leave("");
}
/*
* release or recycle an object that the netfs has discarded
*/
static void fscache_release_object(struct fscache_object *object)
{
_enter("");
fscache_drop_object(object);
}
/*
* withdraw an object from active service
*/
static void fscache_withdraw_object(struct fscache_object *object)
{
struct fscache_cookie *cookie;
bool detached;
_enter("");
spin_lock(&object->lock);
cookie = object->cookie;
if (cookie) {
/* need to get the cookie lock before the object lock, starting
* from the object pointer */
atomic_inc(&cookie->usage);
spin_unlock(&object->lock);
detached = false;
spin_lock(&cookie->lock);
spin_lock(&object->lock);
if (object->cookie == cookie) {
hlist_del_init(&object->cookie_link);
object->cookie = NULL;
detached = true;
}
spin_unlock(&cookie->lock);
fscache_cookie_put(cookie);
if (detached)
fscache_cookie_put(cookie);
}
spin_unlock(&object->lock);
fscache_drop_object(object);
}
/*
* withdraw an object from active service at the behest of the cache
* - need break the links to a cached object cookie
* - called under two situations:
* (1) recycler decides to reclaim an in-use object
* (2) a cache is unmounted
* - have to take care as the cookie can be being relinquished by the netfs
* simultaneously
* - the object is pinned by the caller holding a refcount on it
*/
void fscache_withdrawing_object(struct fscache_cache *cache,
struct fscache_object *object)
{
bool enqueue = false;
_enter(",OBJ%x", object->debug_id);
spin_lock(&object->lock);
if (object->state < FSCACHE_OBJECT_WITHDRAWING) {
object->state = FSCACHE_OBJECT_WITHDRAWING;
enqueue = true;
}
spin_unlock(&object->lock);
if (enqueue)
fscache_enqueue_object(object);
_leave("");
}
/*
* allow the slow work item processor to get a ref on an object
*/
static int fscache_object_slow_work_get_ref(struct slow_work *work)
{
struct fscache_object *object =
container_of(work, struct fscache_object, work);
return object->cache->ops->grab_object(object) ? 0 : -EAGAIN;
}
/*
* allow the slow work item processor to discard a ref on a work item
*/
static void fscache_object_slow_work_put_ref(struct slow_work *work)
{
struct fscache_object *object =
container_of(work, struct fscache_object, work);
return object->cache->ops->put_object(object);
}
/*
* enqueue an object for metadata-type processing
*/
void fscache_enqueue_object(struct fscache_object *object)
{
_enter("{OBJ%x}", object->debug_id);
slow_work_enqueue(&object->work);
}
/*
* enqueue the dependents of an object for metadata-type processing
* - the caller must hold the object's lock
* - this may cause an already locked object to wind up being processed again
*/
static void fscache_enqueue_dependents(struct fscache_object *object)
{
struct fscache_object *dep;
_enter("{OBJ%x}", object->debug_id);
if (list_empty(&object->dependents))
return;
spin_lock(&object->lock);
while (!list_empty(&object->dependents)) {
dep = list_entry(object->dependents.next,
struct fscache_object, dep_link);
list_del_init(&dep->dep_link);
/* sort onto appropriate lists */
fscache_enqueue_object(dep);
dep->cache->ops->put_object(dep);
if (!list_empty(&object->dependents))
cond_resched_lock(&object->lock);
}
spin_unlock(&object->lock);
}
/*
* remove an object from whatever queue it's waiting on
* - the caller must hold object->lock
*/
void fscache_dequeue_object(struct fscache_object *object)
{
_enter("{OBJ%x}", object->debug_id);
if (!list_empty(&object->dep_link)) {
spin_lock(&object->parent->lock);
list_del_init(&object->dep_link);
spin_unlock(&object->parent->lock);
}
_leave("");
}
/**
* fscache_check_aux - Ask the netfs whether an object on disk is still valid
* @object: The object to ask about
* @data: The auxiliary data for the object
* @datalen: The size of the auxiliary data
*
* This function consults the netfs about the coherency state of an object
*/
enum fscache_checkaux fscache_check_aux(struct fscache_object *object,
const void *data, uint16_t datalen)
{
enum fscache_checkaux result;
if (!object->cookie->def->check_aux) {
fscache_stat(&fscache_n_checkaux_none);
return FSCACHE_CHECKAUX_OKAY;
}
result = object->cookie->def->check_aux(object->cookie->netfs_data,
data, datalen);
switch (result) {
/* entry okay as is */
case FSCACHE_CHECKAUX_OKAY:
fscache_stat(&fscache_n_checkaux_okay);
break;
/* entry requires update */
case FSCACHE_CHECKAUX_NEEDS_UPDATE:
fscache_stat(&fscache_n_checkaux_update);
break;
/* entry requires deletion */
case FSCACHE_CHECKAUX_OBSOLETE:
fscache_stat(&fscache_n_checkaux_obsolete);
break;
default:
BUG();
}
return result;
}
EXPORT_SYMBOL(fscache_check_aux);

459
fs/fscache/operation.c Normal file
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@ -0,0 +1,459 @@
/* FS-Cache worker operation management routines
*
* Copyright (C) 2008 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*
* See Documentation/filesystems/caching/operations.txt
*/
#define FSCACHE_DEBUG_LEVEL OPERATION
#include <linux/module.h>
#include "internal.h"
atomic_t fscache_op_debug_id;
EXPORT_SYMBOL(fscache_op_debug_id);
/**
* fscache_enqueue_operation - Enqueue an operation for processing
* @op: The operation to enqueue
*
* Enqueue an operation for processing by the FS-Cache thread pool.
*
* This will get its own ref on the object.
*/
void fscache_enqueue_operation(struct fscache_operation *op)
{
_enter("{OBJ%x OP%x,%u}",
op->object->debug_id, op->debug_id, atomic_read(&op->usage));
ASSERT(op->processor != NULL);
ASSERTCMP(op->object->state, >=, FSCACHE_OBJECT_AVAILABLE);
ASSERTCMP(atomic_read(&op->usage), >, 0);
if (list_empty(&op->pend_link)) {
switch (op->flags & FSCACHE_OP_TYPE) {
case FSCACHE_OP_FAST:
_debug("queue fast");
atomic_inc(&op->usage);
if (!schedule_work(&op->fast_work))
fscache_put_operation(op);
break;
case FSCACHE_OP_SLOW:
_debug("queue slow");
slow_work_enqueue(&op->slow_work);
break;
case FSCACHE_OP_MYTHREAD:
_debug("queue for caller's attention");
break;
default:
printk(KERN_ERR "FS-Cache: Unexpected op type %lx",
op->flags);
BUG();
break;
}
fscache_stat(&fscache_n_op_enqueue);
}
}
EXPORT_SYMBOL(fscache_enqueue_operation);
/*
* start an op running
*/
static void fscache_run_op(struct fscache_object *object,
struct fscache_operation *op)
{
object->n_in_progress++;
if (test_and_clear_bit(FSCACHE_OP_WAITING, &op->flags))
wake_up_bit(&op->flags, FSCACHE_OP_WAITING);
if (op->processor)
fscache_enqueue_operation(op);
fscache_stat(&fscache_n_op_run);
}
/*
* submit an exclusive operation for an object
* - other ops are excluded from running simultaneously with this one
* - this gets any extra refs it needs on an op
*/
int fscache_submit_exclusive_op(struct fscache_object *object,
struct fscache_operation *op)
{
int ret;
_enter("{OBJ%x OP%x},", object->debug_id, op->debug_id);
spin_lock(&object->lock);
ASSERTCMP(object->n_ops, >=, object->n_in_progress);
ASSERTCMP(object->n_ops, >=, object->n_exclusive);
ret = -ENOBUFS;
if (fscache_object_is_active(object)) {
op->object = object;
object->n_ops++;
object->n_exclusive++; /* reads and writes must wait */
if (object->n_ops > 0) {
atomic_inc(&op->usage);
list_add_tail(&op->pend_link, &object->pending_ops);
fscache_stat(&fscache_n_op_pend);
} else if (!list_empty(&object->pending_ops)) {
atomic_inc(&op->usage);
list_add_tail(&op->pend_link, &object->pending_ops);
fscache_stat(&fscache_n_op_pend);
fscache_start_operations(object);
} else {
ASSERTCMP(object->n_in_progress, ==, 0);
fscache_run_op(object, op);
}
/* need to issue a new write op after this */
clear_bit(FSCACHE_OBJECT_PENDING_WRITE, &object->flags);
ret = 0;
} else if (object->state == FSCACHE_OBJECT_CREATING) {
op->object = object;
object->n_ops++;
object->n_exclusive++; /* reads and writes must wait */
atomic_inc(&op->usage);
list_add_tail(&op->pend_link, &object->pending_ops);
fscache_stat(&fscache_n_op_pend);
ret = 0;
} else {
/* not allowed to submit ops in any other state */
BUG();
}
spin_unlock(&object->lock);
return ret;
}
/*
* report an unexpected submission
*/
static void fscache_report_unexpected_submission(struct fscache_object *object,
struct fscache_operation *op,
unsigned long ostate)
{
static bool once_only;
struct fscache_operation *p;
unsigned n;
if (once_only)
return;
once_only = true;
kdebug("unexpected submission OP%x [OBJ%x %s]",
op->debug_id, object->debug_id,
fscache_object_states[object->state]);
kdebug("objstate=%s [%s]",
fscache_object_states[object->state],
fscache_object_states[ostate]);
kdebug("objflags=%lx", object->flags);
kdebug("objevent=%lx [%lx]", object->events, object->event_mask);
kdebug("ops=%u inp=%u exc=%u",
object->n_ops, object->n_in_progress, object->n_exclusive);
if (!list_empty(&object->pending_ops)) {
n = 0;
list_for_each_entry(p, &object->pending_ops, pend_link) {
ASSERTCMP(p->object, ==, object);
kdebug("%p %p", op->processor, op->release);
n++;
}
kdebug("n=%u", n);
}
dump_stack();
}
/*
* submit an operation for an object
* - objects may be submitted only in the following states:
* - during object creation (write ops may be submitted)
* - whilst the object is active
* - after an I/O error incurred in one of the two above states (op rejected)
* - this gets any extra refs it needs on an op
*/
int fscache_submit_op(struct fscache_object *object,
struct fscache_operation *op)
{
unsigned long ostate;
int ret;
_enter("{OBJ%x OP%x},{%u}",
object->debug_id, op->debug_id, atomic_read(&op->usage));
ASSERTCMP(atomic_read(&op->usage), >, 0);
spin_lock(&object->lock);
ASSERTCMP(object->n_ops, >=, object->n_in_progress);
ASSERTCMP(object->n_ops, >=, object->n_exclusive);
ostate = object->state;
smp_rmb();
if (fscache_object_is_active(object)) {
op->object = object;
object->n_ops++;
if (object->n_exclusive > 0) {
atomic_inc(&op->usage);
list_add_tail(&op->pend_link, &object->pending_ops);
fscache_stat(&fscache_n_op_pend);
} else if (!list_empty(&object->pending_ops)) {
atomic_inc(&op->usage);
list_add_tail(&op->pend_link, &object->pending_ops);
fscache_stat(&fscache_n_op_pend);
fscache_start_operations(object);
} else {
ASSERTCMP(object->n_exclusive, ==, 0);
fscache_run_op(object, op);
}
ret = 0;
} else if (object->state == FSCACHE_OBJECT_CREATING) {
op->object = object;
object->n_ops++;
atomic_inc(&op->usage);
list_add_tail(&op->pend_link, &object->pending_ops);
fscache_stat(&fscache_n_op_pend);
ret = 0;
} else if (!test_bit(FSCACHE_IOERROR, &object->cache->flags)) {
fscache_report_unexpected_submission(object, op, ostate);
ASSERT(!fscache_object_is_active(object));
ret = -ENOBUFS;
} else {
ret = -ENOBUFS;
}
spin_unlock(&object->lock);
return ret;
}
/*
* queue an object for withdrawal on error, aborting all following asynchronous
* operations
*/
void fscache_abort_object(struct fscache_object *object)
{
_enter("{OBJ%x}", object->debug_id);
fscache_raise_event(object, FSCACHE_OBJECT_EV_ERROR);
}
/*
* jump start the operation processing on an object
* - caller must hold object->lock
*/
void fscache_start_operations(struct fscache_object *object)
{
struct fscache_operation *op;
bool stop = false;
while (!list_empty(&object->pending_ops) && !stop) {
op = list_entry(object->pending_ops.next,
struct fscache_operation, pend_link);
if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags)) {
if (object->n_in_progress > 0)
break;
stop = true;
}
list_del_init(&op->pend_link);
object->n_in_progress++;
if (test_and_clear_bit(FSCACHE_OP_WAITING, &op->flags))
wake_up_bit(&op->flags, FSCACHE_OP_WAITING);
if (op->processor)
fscache_enqueue_operation(op);
/* the pending queue was holding a ref on the object */
fscache_put_operation(op);
}
ASSERTCMP(object->n_in_progress, <=, object->n_ops);
_debug("woke %d ops on OBJ%x",
object->n_in_progress, object->debug_id);
}
/*
* release an operation
* - queues pending ops if this is the last in-progress op
*/
void fscache_put_operation(struct fscache_operation *op)
{
struct fscache_object *object;
struct fscache_cache *cache;
_enter("{OBJ%x OP%x,%d}",
op->object->debug_id, op->debug_id, atomic_read(&op->usage));
ASSERTCMP(atomic_read(&op->usage), >, 0);
if (!atomic_dec_and_test(&op->usage))
return;
_debug("PUT OP");
if (test_and_set_bit(FSCACHE_OP_DEAD, &op->flags))
BUG();
fscache_stat(&fscache_n_op_release);
if (op->release) {
op->release(op);
op->release = NULL;
}
object = op->object;
/* now... we may get called with the object spinlock held, so we
* complete the cleanup here only if we can immediately acquire the
* lock, and defer it otherwise */
if (!spin_trylock(&object->lock)) {
_debug("defer put");
fscache_stat(&fscache_n_op_deferred_release);
cache = object->cache;
spin_lock(&cache->op_gc_list_lock);
list_add_tail(&op->pend_link, &cache->op_gc_list);
spin_unlock(&cache->op_gc_list_lock);
schedule_work(&cache->op_gc);
_leave(" [defer]");
return;
}
if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags)) {
ASSERTCMP(object->n_exclusive, >, 0);
object->n_exclusive--;
}
ASSERTCMP(object->n_in_progress, >, 0);
object->n_in_progress--;
if (object->n_in_progress == 0)
fscache_start_operations(object);
ASSERTCMP(object->n_ops, >, 0);
object->n_ops--;
if (object->n_ops == 0)
fscache_raise_event(object, FSCACHE_OBJECT_EV_CLEARED);
spin_unlock(&object->lock);
kfree(op);
_leave(" [done]");
}
EXPORT_SYMBOL(fscache_put_operation);
/*
* garbage collect operations that have had their release deferred
*/
void fscache_operation_gc(struct work_struct *work)
{
struct fscache_operation *op;
struct fscache_object *object;
struct fscache_cache *cache =
container_of(work, struct fscache_cache, op_gc);
int count = 0;
_enter("");
do {
spin_lock(&cache->op_gc_list_lock);
if (list_empty(&cache->op_gc_list)) {
spin_unlock(&cache->op_gc_list_lock);
break;
}
op = list_entry(cache->op_gc_list.next,
struct fscache_operation, pend_link);
list_del(&op->pend_link);
spin_unlock(&cache->op_gc_list_lock);
object = op->object;
_debug("GC DEFERRED REL OBJ%x OP%x",
object->debug_id, op->debug_id);
fscache_stat(&fscache_n_op_gc);
ASSERTCMP(atomic_read(&op->usage), ==, 0);
spin_lock(&object->lock);
if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags)) {
ASSERTCMP(object->n_exclusive, >, 0);
object->n_exclusive--;
}
ASSERTCMP(object->n_in_progress, >, 0);
object->n_in_progress--;
if (object->n_in_progress == 0)
fscache_start_operations(object);
ASSERTCMP(object->n_ops, >, 0);
object->n_ops--;
if (object->n_ops == 0)
fscache_raise_event(object, FSCACHE_OBJECT_EV_CLEARED);
spin_unlock(&object->lock);
} while (count++ < 20);
if (!list_empty(&cache->op_gc_list))
schedule_work(&cache->op_gc);
_leave("");
}
/*
* allow the slow work item processor to get a ref on an operation
*/
static int fscache_op_get_ref(struct slow_work *work)
{
struct fscache_operation *op =
container_of(work, struct fscache_operation, slow_work);
atomic_inc(&op->usage);
return 0;
}
/*
* allow the slow work item processor to discard a ref on an operation
*/
static void fscache_op_put_ref(struct slow_work *work)
{
struct fscache_operation *op =
container_of(work, struct fscache_operation, slow_work);
fscache_put_operation(op);
}
/*
* execute an operation using the slow thread pool to provide processing context
* - the caller holds a ref to this object, so we don't need to hold one
*/
static void fscache_op_execute(struct slow_work *work)
{
struct fscache_operation *op =
container_of(work, struct fscache_operation, slow_work);
unsigned long start;
_enter("{OBJ%x OP%x,%d}",
op->object->debug_id, op->debug_id, atomic_read(&op->usage));
ASSERT(op->processor != NULL);
start = jiffies;
op->processor(op);
fscache_hist(fscache_ops_histogram, start);
_leave("");
}
const struct slow_work_ops fscache_op_slow_work_ops = {
.get_ref = fscache_op_get_ref,
.put_ref = fscache_op_put_ref,
.execute = fscache_op_execute,
};

816
fs/fscache/page.c Normal file
View File

@ -0,0 +1,816 @@
/* Cache page management and data I/O routines
*
* Copyright (C) 2004-2008 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#define FSCACHE_DEBUG_LEVEL PAGE
#include <linux/module.h>
#include <linux/fscache-cache.h>
#include <linux/buffer_head.h>
#include <linux/pagevec.h>
#include "internal.h"
/*
* check to see if a page is being written to the cache
*/
bool __fscache_check_page_write(struct fscache_cookie *cookie, struct page *page)
{
void *val;
rcu_read_lock();
val = radix_tree_lookup(&cookie->stores, page->index);
rcu_read_unlock();
return val != NULL;
}
EXPORT_SYMBOL(__fscache_check_page_write);
/*
* wait for a page to finish being written to the cache
*/
void __fscache_wait_on_page_write(struct fscache_cookie *cookie, struct page *page)
{
wait_queue_head_t *wq = bit_waitqueue(&cookie->flags, 0);
wait_event(*wq, !__fscache_check_page_write(cookie, page));
}
EXPORT_SYMBOL(__fscache_wait_on_page_write);
/*
* note that a page has finished being written to the cache
*/
static void fscache_end_page_write(struct fscache_cookie *cookie, struct page *page)
{
struct page *xpage;
spin_lock(&cookie->lock);
xpage = radix_tree_delete(&cookie->stores, page->index);
spin_unlock(&cookie->lock);
ASSERT(xpage != NULL);
wake_up_bit(&cookie->flags, 0);
}
/*
* actually apply the changed attributes to a cache object
*/
static void fscache_attr_changed_op(struct fscache_operation *op)
{
struct fscache_object *object = op->object;
_enter("{OBJ%x OP%x}", object->debug_id, op->debug_id);
fscache_stat(&fscache_n_attr_changed_calls);
if (fscache_object_is_active(object) &&
object->cache->ops->attr_changed(object) < 0)
fscache_abort_object(object);
_leave("");
}
/*
* notification that the attributes on an object have changed
*/
int __fscache_attr_changed(struct fscache_cookie *cookie)
{
struct fscache_operation *op;
struct fscache_object *object;
_enter("%p", cookie);
ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX);
fscache_stat(&fscache_n_attr_changed);
op = kzalloc(sizeof(*op), GFP_KERNEL);
if (!op) {
fscache_stat(&fscache_n_attr_changed_nomem);
_leave(" = -ENOMEM");
return -ENOMEM;
}
fscache_operation_init(op, NULL);
fscache_operation_init_slow(op, fscache_attr_changed_op);
op->flags = FSCACHE_OP_SLOW | (1 << FSCACHE_OP_EXCLUSIVE);
spin_lock(&cookie->lock);
if (hlist_empty(&cookie->backing_objects))
goto nobufs;
object = hlist_entry(cookie->backing_objects.first,
struct fscache_object, cookie_link);
if (fscache_submit_exclusive_op(object, op) < 0)
goto nobufs;
spin_unlock(&cookie->lock);
fscache_stat(&fscache_n_attr_changed_ok);
fscache_put_operation(op);
_leave(" = 0");
return 0;
nobufs:
spin_unlock(&cookie->lock);
kfree(op);
fscache_stat(&fscache_n_attr_changed_nobufs);
_leave(" = %d", -ENOBUFS);
return -ENOBUFS;
}
EXPORT_SYMBOL(__fscache_attr_changed);
/*
* handle secondary execution given to a retrieval op on behalf of the
* cache
*/
static void fscache_retrieval_work(struct work_struct *work)
{
struct fscache_retrieval *op =
container_of(work, struct fscache_retrieval, op.fast_work);
unsigned long start;
_enter("{OP%x}", op->op.debug_id);
start = jiffies;
op->op.processor(&op->op);
fscache_hist(fscache_ops_histogram, start);
fscache_put_operation(&op->op);
}
/*
* release a retrieval op reference
*/
static void fscache_release_retrieval_op(struct fscache_operation *_op)
{
struct fscache_retrieval *op =
container_of(_op, struct fscache_retrieval, op);
_enter("{OP%x}", op->op.debug_id);
fscache_hist(fscache_retrieval_histogram, op->start_time);
if (op->context)
fscache_put_context(op->op.object->cookie, op->context);
_leave("");
}
/*
* allocate a retrieval op
*/
static struct fscache_retrieval *fscache_alloc_retrieval(
struct address_space *mapping,
fscache_rw_complete_t end_io_func,
void *context)
{
struct fscache_retrieval *op;
/* allocate a retrieval operation and attempt to submit it */
op = kzalloc(sizeof(*op), GFP_NOIO);
if (!op) {
fscache_stat(&fscache_n_retrievals_nomem);
return NULL;
}
fscache_operation_init(&op->op, fscache_release_retrieval_op);
op->op.flags = FSCACHE_OP_MYTHREAD | (1 << FSCACHE_OP_WAITING);
op->mapping = mapping;
op->end_io_func = end_io_func;
op->context = context;
op->start_time = jiffies;
INIT_WORK(&op->op.fast_work, fscache_retrieval_work);
INIT_LIST_HEAD(&op->to_do);
return op;
}
/*
* wait for a deferred lookup to complete
*/
static int fscache_wait_for_deferred_lookup(struct fscache_cookie *cookie)
{
unsigned long jif;
_enter("");
if (!test_bit(FSCACHE_COOKIE_LOOKING_UP, &cookie->flags)) {
_leave(" = 0 [imm]");
return 0;
}
fscache_stat(&fscache_n_retrievals_wait);
jif = jiffies;
if (wait_on_bit(&cookie->flags, FSCACHE_COOKIE_LOOKING_UP,
fscache_wait_bit_interruptible,
TASK_INTERRUPTIBLE) != 0) {
fscache_stat(&fscache_n_retrievals_intr);
_leave(" = -ERESTARTSYS");
return -ERESTARTSYS;
}
ASSERT(!test_bit(FSCACHE_COOKIE_LOOKING_UP, &cookie->flags));
smp_rmb();
fscache_hist(fscache_retrieval_delay_histogram, jif);
_leave(" = 0 [dly]");
return 0;
}
/*
* read a page from the cache or allocate a block in which to store it
* - we return:
* -ENOMEM - out of memory, nothing done
* -ERESTARTSYS - interrupted
* -ENOBUFS - no backing object available in which to cache the block
* -ENODATA - no data available in the backing object for this block
* 0 - dispatched a read - it'll call end_io_func() when finished
*/
int __fscache_read_or_alloc_page(struct fscache_cookie *cookie,
struct page *page,
fscache_rw_complete_t end_io_func,
void *context,
gfp_t gfp)
{
struct fscache_retrieval *op;
struct fscache_object *object;
int ret;
_enter("%p,%p,,,", cookie, page);
fscache_stat(&fscache_n_retrievals);
if (hlist_empty(&cookie->backing_objects))
goto nobufs;
ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX);
ASSERTCMP(page, !=, NULL);
if (fscache_wait_for_deferred_lookup(cookie) < 0)
return -ERESTARTSYS;
op = fscache_alloc_retrieval(page->mapping, end_io_func, context);
if (!op) {
_leave(" = -ENOMEM");
return -ENOMEM;
}
spin_lock(&cookie->lock);
if (hlist_empty(&cookie->backing_objects))
goto nobufs_unlock;
object = hlist_entry(cookie->backing_objects.first,
struct fscache_object, cookie_link);
ASSERTCMP(object->state, >, FSCACHE_OBJECT_LOOKING_UP);
if (fscache_submit_op(object, &op->op) < 0)
goto nobufs_unlock;
spin_unlock(&cookie->lock);
fscache_stat(&fscache_n_retrieval_ops);
/* pin the netfs read context in case we need to do the actual netfs
* read because we've encountered a cache read failure */
fscache_get_context(object->cookie, op->context);
/* we wait for the operation to become active, and then process it
* *here*, in this thread, and not in the thread pool */
if (test_bit(FSCACHE_OP_WAITING, &op->op.flags)) {
_debug(">>> WT");
fscache_stat(&fscache_n_retrieval_op_waits);
wait_on_bit(&op->op.flags, FSCACHE_OP_WAITING,
fscache_wait_bit, TASK_UNINTERRUPTIBLE);
_debug("<<< GO");
}
/* ask the cache to honour the operation */
if (test_bit(FSCACHE_COOKIE_NO_DATA_YET, &object->cookie->flags)) {
ret = object->cache->ops->allocate_page(op, page, gfp);
if (ret == 0)
ret = -ENODATA;
} else {
ret = object->cache->ops->read_or_alloc_page(op, page, gfp);
}
if (ret == -ENOMEM)
fscache_stat(&fscache_n_retrievals_nomem);
else if (ret == -ERESTARTSYS)
fscache_stat(&fscache_n_retrievals_intr);
else if (ret == -ENODATA)
fscache_stat(&fscache_n_retrievals_nodata);
else if (ret < 0)
fscache_stat(&fscache_n_retrievals_nobufs);
else
fscache_stat(&fscache_n_retrievals_ok);
fscache_put_retrieval(op);
_leave(" = %d", ret);
return ret;
nobufs_unlock:
spin_unlock(&cookie->lock);
kfree(op);
nobufs:
fscache_stat(&fscache_n_retrievals_nobufs);
_leave(" = -ENOBUFS");
return -ENOBUFS;
}
EXPORT_SYMBOL(__fscache_read_or_alloc_page);
/*
* read a list of page from the cache or allocate a block in which to store
* them
* - we return:
* -ENOMEM - out of memory, some pages may be being read
* -ERESTARTSYS - interrupted, some pages may be being read
* -ENOBUFS - no backing object or space available in which to cache any
* pages not being read
* -ENODATA - no data available in the backing object for some or all of
* the pages
* 0 - dispatched a read on all pages
*
* end_io_func() will be called for each page read from the cache as it is
* finishes being read
*
* any pages for which a read is dispatched will be removed from pages and
* nr_pages
*/
int __fscache_read_or_alloc_pages(struct fscache_cookie *cookie,
struct address_space *mapping,
struct list_head *pages,
unsigned *nr_pages,
fscache_rw_complete_t end_io_func,
void *context,
gfp_t gfp)
{
fscache_pages_retrieval_func_t func;
struct fscache_retrieval *op;
struct fscache_object *object;
int ret;
_enter("%p,,%d,,,", cookie, *nr_pages);
fscache_stat(&fscache_n_retrievals);
if (hlist_empty(&cookie->backing_objects))
goto nobufs;
ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX);
ASSERTCMP(*nr_pages, >, 0);
ASSERT(!list_empty(pages));
if (fscache_wait_for_deferred_lookup(cookie) < 0)
return -ERESTARTSYS;
op = fscache_alloc_retrieval(mapping, end_io_func, context);
if (!op)
return -ENOMEM;
spin_lock(&cookie->lock);
if (hlist_empty(&cookie->backing_objects))
goto nobufs_unlock;
object = hlist_entry(cookie->backing_objects.first,
struct fscache_object, cookie_link);
if (fscache_submit_op(object, &op->op) < 0)
goto nobufs_unlock;
spin_unlock(&cookie->lock);
fscache_stat(&fscache_n_retrieval_ops);
/* pin the netfs read context in case we need to do the actual netfs
* read because we've encountered a cache read failure */
fscache_get_context(object->cookie, op->context);
/* we wait for the operation to become active, and then process it
* *here*, in this thread, and not in the thread pool */
if (test_bit(FSCACHE_OP_WAITING, &op->op.flags)) {
_debug(">>> WT");
fscache_stat(&fscache_n_retrieval_op_waits);
wait_on_bit(&op->op.flags, FSCACHE_OP_WAITING,
fscache_wait_bit, TASK_UNINTERRUPTIBLE);
_debug("<<< GO");
}
/* ask the cache to honour the operation */
if (test_bit(FSCACHE_COOKIE_NO_DATA_YET, &object->cookie->flags))
func = object->cache->ops->allocate_pages;
else
func = object->cache->ops->read_or_alloc_pages;
ret = func(op, pages, nr_pages, gfp);
if (ret == -ENOMEM)
fscache_stat(&fscache_n_retrievals_nomem);
else if (ret == -ERESTARTSYS)
fscache_stat(&fscache_n_retrievals_intr);
else if (ret == -ENODATA)
fscache_stat(&fscache_n_retrievals_nodata);
else if (ret < 0)
fscache_stat(&fscache_n_retrievals_nobufs);
else
fscache_stat(&fscache_n_retrievals_ok);
fscache_put_retrieval(op);
_leave(" = %d", ret);
return ret;
nobufs_unlock:
spin_unlock(&cookie->lock);
kfree(op);
nobufs:
fscache_stat(&fscache_n_retrievals_nobufs);
_leave(" = -ENOBUFS");
return -ENOBUFS;
}
EXPORT_SYMBOL(__fscache_read_or_alloc_pages);
/*
* allocate a block in the cache on which to store a page
* - we return:
* -ENOMEM - out of memory, nothing done
* -ERESTARTSYS - interrupted
* -ENOBUFS - no backing object available in which to cache the block
* 0 - block allocated
*/
int __fscache_alloc_page(struct fscache_cookie *cookie,
struct page *page,
gfp_t gfp)
{
struct fscache_retrieval *op;
struct fscache_object *object;
int ret;
_enter("%p,%p,,,", cookie, page);
fscache_stat(&fscache_n_allocs);
if (hlist_empty(&cookie->backing_objects))
goto nobufs;
ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX);
ASSERTCMP(page, !=, NULL);
if (fscache_wait_for_deferred_lookup(cookie) < 0)
return -ERESTARTSYS;
op = fscache_alloc_retrieval(page->mapping, NULL, NULL);
if (!op)
return -ENOMEM;
spin_lock(&cookie->lock);
if (hlist_empty(&cookie->backing_objects))
goto nobufs_unlock;
object = hlist_entry(cookie->backing_objects.first,
struct fscache_object, cookie_link);
if (fscache_submit_op(object, &op->op) < 0)
goto nobufs_unlock;
spin_unlock(&cookie->lock);
fscache_stat(&fscache_n_alloc_ops);
if (test_bit(FSCACHE_OP_WAITING, &op->op.flags)) {
_debug(">>> WT");
fscache_stat(&fscache_n_alloc_op_waits);
wait_on_bit(&op->op.flags, FSCACHE_OP_WAITING,
fscache_wait_bit, TASK_UNINTERRUPTIBLE);
_debug("<<< GO");
}
/* ask the cache to honour the operation */
ret = object->cache->ops->allocate_page(op, page, gfp);
if (ret < 0)
fscache_stat(&fscache_n_allocs_nobufs);
else
fscache_stat(&fscache_n_allocs_ok);
fscache_put_retrieval(op);
_leave(" = %d", ret);
return ret;
nobufs_unlock:
spin_unlock(&cookie->lock);
kfree(op);
nobufs:
fscache_stat(&fscache_n_allocs_nobufs);
_leave(" = -ENOBUFS");
return -ENOBUFS;
}
EXPORT_SYMBOL(__fscache_alloc_page);
/*
* release a write op reference
*/
static void fscache_release_write_op(struct fscache_operation *_op)
{
_enter("{OP%x}", _op->debug_id);
}
/*
* perform the background storage of a page into the cache
*/
static void fscache_write_op(struct fscache_operation *_op)
{
struct fscache_storage *op =
container_of(_op, struct fscache_storage, op);
struct fscache_object *object = op->op.object;
struct fscache_cookie *cookie = object->cookie;
struct page *page;
unsigned n;
void *results[1];
int ret;
_enter("{OP%x,%d}", op->op.debug_id, atomic_read(&op->op.usage));
spin_lock(&cookie->lock);
spin_lock(&object->lock);
if (!fscache_object_is_active(object)) {
spin_unlock(&object->lock);
spin_unlock(&cookie->lock);
_leave("");
return;
}
fscache_stat(&fscache_n_store_calls);
/* find a page to store */
page = NULL;
n = radix_tree_gang_lookup_tag(&cookie->stores, results, 0, 1,
FSCACHE_COOKIE_PENDING_TAG);
if (n != 1)
goto superseded;
page = results[0];
_debug("gang %d [%lx]", n, page->index);
if (page->index > op->store_limit)
goto superseded;
radix_tree_tag_clear(&cookie->stores, page->index,
FSCACHE_COOKIE_PENDING_TAG);
spin_unlock(&object->lock);
spin_unlock(&cookie->lock);
if (page) {
ret = object->cache->ops->write_page(op, page);
fscache_end_page_write(cookie, page);
page_cache_release(page);
if (ret < 0)
fscache_abort_object(object);
else
fscache_enqueue_operation(&op->op);
}
_leave("");
return;
superseded:
/* this writer is going away and there aren't any more things to
* write */
_debug("cease");
clear_bit(FSCACHE_OBJECT_PENDING_WRITE, &object->flags);
spin_unlock(&object->lock);
spin_unlock(&cookie->lock);
_leave("");
}
/*
* request a page be stored in the cache
* - returns:
* -ENOMEM - out of memory, nothing done
* -ENOBUFS - no backing object available in which to cache the page
* 0 - dispatched a write - it'll call end_io_func() when finished
*
* if the cookie still has a backing object at this point, that object can be
* in one of a few states with respect to storage processing:
*
* (1) negative lookup, object not yet created (FSCACHE_COOKIE_CREATING is
* set)
*
* (a) no writes yet (set FSCACHE_COOKIE_PENDING_FILL and queue deferred
* fill op)
*
* (b) writes deferred till post-creation (mark page for writing and
* return immediately)
*
* (2) negative lookup, object created, initial fill being made from netfs
* (FSCACHE_COOKIE_INITIAL_FILL is set)
*
* (a) fill point not yet reached this page (mark page for writing and
* return)
*
* (b) fill point passed this page (queue op to store this page)
*
* (3) object extant (queue op to store this page)
*
* any other state is invalid
*/
int __fscache_write_page(struct fscache_cookie *cookie,
struct page *page,
gfp_t gfp)
{
struct fscache_storage *op;
struct fscache_object *object;
int ret;
_enter("%p,%x,", cookie, (u32) page->flags);
ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX);
ASSERT(PageFsCache(page));
fscache_stat(&fscache_n_stores);
op = kzalloc(sizeof(*op), GFP_NOIO);
if (!op)
goto nomem;
fscache_operation_init(&op->op, fscache_release_write_op);
fscache_operation_init_slow(&op->op, fscache_write_op);
op->op.flags = FSCACHE_OP_SLOW | (1 << FSCACHE_OP_WAITING);
ret = radix_tree_preload(gfp & ~__GFP_HIGHMEM);
if (ret < 0)
goto nomem_free;
ret = -ENOBUFS;
spin_lock(&cookie->lock);
if (hlist_empty(&cookie->backing_objects))
goto nobufs;
object = hlist_entry(cookie->backing_objects.first,
struct fscache_object, cookie_link);
if (test_bit(FSCACHE_IOERROR, &object->cache->flags))
goto nobufs;
/* add the page to the pending-storage radix tree on the backing
* object */
spin_lock(&object->lock);
_debug("store limit %llx", (unsigned long long) object->store_limit);
ret = radix_tree_insert(&cookie->stores, page->index, page);
if (ret < 0) {
if (ret == -EEXIST)
goto already_queued;
_debug("insert failed %d", ret);
goto nobufs_unlock_obj;
}
radix_tree_tag_set(&cookie->stores, page->index,
FSCACHE_COOKIE_PENDING_TAG);
page_cache_get(page);
/* we only want one writer at a time, but we do need to queue new
* writers after exclusive ops */
if (test_and_set_bit(FSCACHE_OBJECT_PENDING_WRITE, &object->flags))
goto already_pending;
spin_unlock(&object->lock);
op->op.debug_id = atomic_inc_return(&fscache_op_debug_id);
op->store_limit = object->store_limit;
if (fscache_submit_op(object, &op->op) < 0)
goto submit_failed;
spin_unlock(&cookie->lock);
radix_tree_preload_end();
fscache_stat(&fscache_n_store_ops);
fscache_stat(&fscache_n_stores_ok);
/* the slow work queue now carries its own ref on the object */
fscache_put_operation(&op->op);
_leave(" = 0");
return 0;
already_queued:
fscache_stat(&fscache_n_stores_again);
already_pending:
spin_unlock(&object->lock);
spin_unlock(&cookie->lock);
radix_tree_preload_end();
kfree(op);
fscache_stat(&fscache_n_stores_ok);
_leave(" = 0");
return 0;
submit_failed:
radix_tree_delete(&cookie->stores, page->index);
page_cache_release(page);
ret = -ENOBUFS;
goto nobufs;
nobufs_unlock_obj:
spin_unlock(&object->lock);
nobufs:
spin_unlock(&cookie->lock);
radix_tree_preload_end();
kfree(op);
fscache_stat(&fscache_n_stores_nobufs);
_leave(" = -ENOBUFS");
return -ENOBUFS;
nomem_free:
kfree(op);
nomem:
fscache_stat(&fscache_n_stores_oom);
_leave(" = -ENOMEM");
return -ENOMEM;
}
EXPORT_SYMBOL(__fscache_write_page);
/*
* remove a page from the cache
*/
void __fscache_uncache_page(struct fscache_cookie *cookie, struct page *page)
{
struct fscache_object *object;
_enter(",%p", page);
ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX);
ASSERTCMP(page, !=, NULL);
fscache_stat(&fscache_n_uncaches);
/* cache withdrawal may beat us to it */
if (!PageFsCache(page))
goto done;
/* get the object */
spin_lock(&cookie->lock);
if (hlist_empty(&cookie->backing_objects)) {
ClearPageFsCache(page);
goto done_unlock;
}
object = hlist_entry(cookie->backing_objects.first,
struct fscache_object, cookie_link);
/* there might now be stuff on disk we could read */
clear_bit(FSCACHE_COOKIE_NO_DATA_YET, &cookie->flags);
/* only invoke the cache backend if we managed to mark the page
* uncached here; this deals with synchronisation vs withdrawal */
if (TestClearPageFsCache(page) &&
object->cache->ops->uncache_page) {
/* the cache backend releases the cookie lock */
object->cache->ops->uncache_page(object, page);
goto done;
}
done_unlock:
spin_unlock(&cookie->lock);
done:
_leave("");
}
EXPORT_SYMBOL(__fscache_uncache_page);
/**
* fscache_mark_pages_cached - Mark pages as being cached
* @op: The retrieval op pages are being marked for
* @pagevec: The pages to be marked
*
* Mark a bunch of netfs pages as being cached. After this is called,
* the netfs must call fscache_uncache_page() to remove the mark.
*/
void fscache_mark_pages_cached(struct fscache_retrieval *op,
struct pagevec *pagevec)
{
struct fscache_cookie *cookie = op->op.object->cookie;
unsigned long loop;
#ifdef CONFIG_FSCACHE_STATS
atomic_add(pagevec->nr, &fscache_n_marks);
#endif
for (loop = 0; loop < pagevec->nr; loop++) {
struct page *page = pagevec->pages[loop];
_debug("- mark %p{%lx}", page, page->index);
if (TestSetPageFsCache(page)) {
static bool once_only;
if (!once_only) {
once_only = true;
printk(KERN_WARNING "FS-Cache:"
" Cookie type %s marked page %lx"
" multiple times\n",
cookie->def->name, page->index);
}
}
}
if (cookie->def->mark_pages_cached)
cookie->def->mark_pages_cached(cookie->netfs_data,
op->mapping, pagevec);
pagevec_reinit(pagevec);
}
EXPORT_SYMBOL(fscache_mark_pages_cached);

68
fs/fscache/proc.c Normal file
View File

@ -0,0 +1,68 @@
/* FS-Cache statistics viewing interface
*
* Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#define FSCACHE_DEBUG_LEVEL OPERATION
#include <linux/module.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include "internal.h"
/*
* initialise the /proc/fs/fscache/ directory
*/
int __init fscache_proc_init(void)
{
_enter("");
if (!proc_mkdir("fs/fscache", NULL))
goto error_dir;
#ifdef CONFIG_FSCACHE_STATS
if (!proc_create("fs/fscache/stats", S_IFREG | 0444, NULL,
&fscache_stats_fops))
goto error_stats;
#endif
#ifdef CONFIG_FSCACHE_HISTOGRAM
if (!proc_create("fs/fscache/histogram", S_IFREG | 0444, NULL,
&fscache_histogram_fops))
goto error_histogram;
#endif
_leave(" = 0");
return 0;
#ifdef CONFIG_FSCACHE_HISTOGRAM
error_histogram:
#endif
#ifdef CONFIG_FSCACHE_STATS
remove_proc_entry("fs/fscache/stats", NULL);
error_stats:
#endif
remove_proc_entry("fs/fscache", NULL);
error_dir:
_leave(" = -ENOMEM");
return -ENOMEM;
}
/*
* clean up the /proc/fs/fscache/ directory
*/
void fscache_proc_cleanup(void)
{
#ifdef CONFIG_FSCACHE_HISTOGRAM
remove_proc_entry("fs/fscache/histogram", NULL);
#endif
#ifdef CONFIG_FSCACHE_STATS
remove_proc_entry("fs/fscache/stats", NULL);
#endif
remove_proc_entry("fs/fscache", NULL);
}

212
fs/fscache/stats.c Normal file
View File

@ -0,0 +1,212 @@
/* FS-Cache statistics
*
* Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#define FSCACHE_DEBUG_LEVEL THREAD
#include <linux/module.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include "internal.h"
/*
* operation counters
*/
atomic_t fscache_n_op_pend;
atomic_t fscache_n_op_run;
atomic_t fscache_n_op_enqueue;
atomic_t fscache_n_op_requeue;
atomic_t fscache_n_op_deferred_release;
atomic_t fscache_n_op_release;
atomic_t fscache_n_op_gc;
atomic_t fscache_n_attr_changed;
atomic_t fscache_n_attr_changed_ok;
atomic_t fscache_n_attr_changed_nobufs;
atomic_t fscache_n_attr_changed_nomem;
atomic_t fscache_n_attr_changed_calls;
atomic_t fscache_n_allocs;
atomic_t fscache_n_allocs_ok;
atomic_t fscache_n_allocs_wait;
atomic_t fscache_n_allocs_nobufs;
atomic_t fscache_n_alloc_ops;
atomic_t fscache_n_alloc_op_waits;
atomic_t fscache_n_retrievals;
atomic_t fscache_n_retrievals_ok;
atomic_t fscache_n_retrievals_wait;
atomic_t fscache_n_retrievals_nodata;
atomic_t fscache_n_retrievals_nobufs;
atomic_t fscache_n_retrievals_intr;
atomic_t fscache_n_retrievals_nomem;
atomic_t fscache_n_retrieval_ops;
atomic_t fscache_n_retrieval_op_waits;
atomic_t fscache_n_stores;
atomic_t fscache_n_stores_ok;
atomic_t fscache_n_stores_again;
atomic_t fscache_n_stores_nobufs;
atomic_t fscache_n_stores_oom;
atomic_t fscache_n_store_ops;
atomic_t fscache_n_store_calls;
atomic_t fscache_n_marks;
atomic_t fscache_n_uncaches;
atomic_t fscache_n_acquires;
atomic_t fscache_n_acquires_null;
atomic_t fscache_n_acquires_no_cache;
atomic_t fscache_n_acquires_ok;
atomic_t fscache_n_acquires_nobufs;
atomic_t fscache_n_acquires_oom;
atomic_t fscache_n_updates;
atomic_t fscache_n_updates_null;
atomic_t fscache_n_updates_run;
atomic_t fscache_n_relinquishes;
atomic_t fscache_n_relinquishes_null;
atomic_t fscache_n_relinquishes_waitcrt;
atomic_t fscache_n_cookie_index;
atomic_t fscache_n_cookie_data;
atomic_t fscache_n_cookie_special;
atomic_t fscache_n_object_alloc;
atomic_t fscache_n_object_no_alloc;
atomic_t fscache_n_object_lookups;
atomic_t fscache_n_object_lookups_negative;
atomic_t fscache_n_object_lookups_positive;
atomic_t fscache_n_object_created;
atomic_t fscache_n_object_avail;
atomic_t fscache_n_object_dead;
atomic_t fscache_n_checkaux_none;
atomic_t fscache_n_checkaux_okay;
atomic_t fscache_n_checkaux_update;
atomic_t fscache_n_checkaux_obsolete;
/*
* display the general statistics
*/
static int fscache_stats_show(struct seq_file *m, void *v)
{
seq_puts(m, "FS-Cache statistics\n");
seq_printf(m, "Cookies: idx=%u dat=%u spc=%u\n",
atomic_read(&fscache_n_cookie_index),
atomic_read(&fscache_n_cookie_data),
atomic_read(&fscache_n_cookie_special));
seq_printf(m, "Objects: alc=%u nal=%u avl=%u ded=%u\n",
atomic_read(&fscache_n_object_alloc),
atomic_read(&fscache_n_object_no_alloc),
atomic_read(&fscache_n_object_avail),
atomic_read(&fscache_n_object_dead));
seq_printf(m, "ChkAux : non=%u ok=%u upd=%u obs=%u\n",
atomic_read(&fscache_n_checkaux_none),
atomic_read(&fscache_n_checkaux_okay),
atomic_read(&fscache_n_checkaux_update),
atomic_read(&fscache_n_checkaux_obsolete));
seq_printf(m, "Pages : mrk=%u unc=%u\n",
atomic_read(&fscache_n_marks),
atomic_read(&fscache_n_uncaches));
seq_printf(m, "Acquire: n=%u nul=%u noc=%u ok=%u nbf=%u"
" oom=%u\n",
atomic_read(&fscache_n_acquires),
atomic_read(&fscache_n_acquires_null),
atomic_read(&fscache_n_acquires_no_cache),
atomic_read(&fscache_n_acquires_ok),
atomic_read(&fscache_n_acquires_nobufs),
atomic_read(&fscache_n_acquires_oom));
seq_printf(m, "Lookups: n=%u neg=%u pos=%u crt=%u\n",
atomic_read(&fscache_n_object_lookups),
atomic_read(&fscache_n_object_lookups_negative),
atomic_read(&fscache_n_object_lookups_positive),
atomic_read(&fscache_n_object_created));
seq_printf(m, "Updates: n=%u nul=%u run=%u\n",
atomic_read(&fscache_n_updates),
atomic_read(&fscache_n_updates_null),
atomic_read(&fscache_n_updates_run));
seq_printf(m, "Relinqs: n=%u nul=%u wcr=%u\n",
atomic_read(&fscache_n_relinquishes),
atomic_read(&fscache_n_relinquishes_null),
atomic_read(&fscache_n_relinquishes_waitcrt));
seq_printf(m, "AttrChg: n=%u ok=%u nbf=%u oom=%u run=%u\n",
atomic_read(&fscache_n_attr_changed),
atomic_read(&fscache_n_attr_changed_ok),
atomic_read(&fscache_n_attr_changed_nobufs),
atomic_read(&fscache_n_attr_changed_nomem),
atomic_read(&fscache_n_attr_changed_calls));
seq_printf(m, "Allocs : n=%u ok=%u wt=%u nbf=%u\n",
atomic_read(&fscache_n_allocs),
atomic_read(&fscache_n_allocs_ok),
atomic_read(&fscache_n_allocs_wait),
atomic_read(&fscache_n_allocs_nobufs));
seq_printf(m, "Allocs : ops=%u owt=%u\n",
atomic_read(&fscache_n_alloc_ops),
atomic_read(&fscache_n_alloc_op_waits));
seq_printf(m, "Retrvls: n=%u ok=%u wt=%u nod=%u nbf=%u"
" int=%u oom=%u\n",
atomic_read(&fscache_n_retrievals),
atomic_read(&fscache_n_retrievals_ok),
atomic_read(&fscache_n_retrievals_wait),
atomic_read(&fscache_n_retrievals_nodata),
atomic_read(&fscache_n_retrievals_nobufs),
atomic_read(&fscache_n_retrievals_intr),
atomic_read(&fscache_n_retrievals_nomem));
seq_printf(m, "Retrvls: ops=%u owt=%u\n",
atomic_read(&fscache_n_retrieval_ops),
atomic_read(&fscache_n_retrieval_op_waits));
seq_printf(m, "Stores : n=%u ok=%u agn=%u nbf=%u oom=%u\n",
atomic_read(&fscache_n_stores),
atomic_read(&fscache_n_stores_ok),
atomic_read(&fscache_n_stores_again),
atomic_read(&fscache_n_stores_nobufs),
atomic_read(&fscache_n_stores_oom));
seq_printf(m, "Stores : ops=%u run=%u\n",
atomic_read(&fscache_n_store_ops),
atomic_read(&fscache_n_store_calls));
seq_printf(m, "Ops : pend=%u run=%u enq=%u\n",
atomic_read(&fscache_n_op_pend),
atomic_read(&fscache_n_op_run),
atomic_read(&fscache_n_op_enqueue));
seq_printf(m, "Ops : dfr=%u rel=%u gc=%u\n",
atomic_read(&fscache_n_op_deferred_release),
atomic_read(&fscache_n_op_release),
atomic_read(&fscache_n_op_gc));
return 0;
}
/*
* open "/proc/fs/fscache/stats" allowing provision of a statistical summary
*/
static int fscache_stats_open(struct inode *inode, struct file *file)
{
return single_open(file, fscache_stats_show, NULL);
}
const struct file_operations fscache_stats_fops = {
.owner = THIS_MODULE,
.open = fscache_stats_open,
.read = seq_read,
.llseek = seq_lseek,
.release = seq_release,
};

8
fs/nfs/Kconfig
View File

@ -84,3 +84,11 @@ config ROOT_NFS
<file:Documentation/filesystems/nfsroot.txt>.
Most people say N here.
config NFS_FSCACHE
bool "Provide NFS client caching support (EXPERIMENTAL)"
depends on EXPERIMENTAL
depends on NFS_FS=m && FSCACHE || NFS_FS=y && FSCACHE=y
help
Say Y here if you want NFS data to be cached locally on disc through
the general filesystem cache manager

1
fs/nfs/Makefile
View File

@ -15,3 +15,4 @@ nfs-$(CONFIG_NFS_V4) += nfs4proc.o nfs4xdr.o nfs4state.o nfs4renewd.o \
callback.o callback_xdr.o callback_proc.o \
nfs4namespace.o
nfs-$(CONFIG_SYSCTL) += sysctl.o
nfs-$(CONFIG_NFS_FSCACHE) += fscache.o fscache-index.o

14
fs/nfs/client.c
View File

@ -45,6 +45,7 @@
#include "delegation.h"
#include "iostat.h"
#include "internal.h"
#include "fscache.h"
#define NFSDBG_FACILITY NFSDBG_CLIENT
@ -154,6 +155,8 @@ static struct nfs_client *nfs_alloc_client(const struct nfs_client_initdata *cl_
if (!IS_ERR(cred))
clp->cl_machine_cred = cred;
nfs_fscache_get_client_cookie(clp);
return clp;
error_3:
@ -187,6 +190,8 @@ static void nfs_free_client(struct nfs_client *clp)
nfs4_shutdown_client(clp);
nfs_fscache_release_client_cookie(clp);
/* -EIO all pending I/O */
if (!IS_ERR(clp->cl_rpcclient))
rpc_shutdown_client(clp->cl_rpcclient);
@ -760,6 +765,7 @@ static int nfs_init_server(struct nfs_server *server,
/* Initialise the client representation from the mount data */
server->flags = data->flags;
server->options = data->options;
if (data->rsize)
server->rsize = nfs_block_size(data->rsize, NULL);
@ -1148,6 +1154,7 @@ static int nfs4_init_server(struct nfs_server *server,
/* Initialise the client representation from the mount data */
server->flags = data->flags;
server->caps |= NFS_CAP_ATOMIC_OPEN;
server->options = data->options;
/* Get a client record */
error = nfs4_set_client(server,
@ -1559,7 +1566,7 @@ static int nfs_volume_list_show(struct seq_file *m, void *v)
/* display header on line 1 */
if (v == &nfs_volume_list) {
seq_puts(m, "NV SERVER PORT DEV FSID\n");
seq_puts(m, "NV SERVER PORT DEV FSID FSC\n");
return 0;
}
/* display one transport per line on subsequent lines */
@ -1573,12 +1580,13 @@ static int nfs_volume_list_show(struct seq_file *m, void *v)
(unsigned long long) server->fsid.major,
(unsigned long long) server->fsid.minor);
seq_printf(m, "v%u %s %s %-7s %-17s\n",
seq_printf(m, "v%u %s %s %-7s %-17s %s\n",
clp->rpc_ops->version,
rpc_peeraddr2str(clp->cl_rpcclient, RPC_DISPLAY_HEX_ADDR),
rpc_peeraddr2str(clp->cl_rpcclient, RPC_DISPLAY_HEX_PORT),
dev,
fsid);
fsid,
nfs_server_fscache_state(server));
return 0;
}

38
fs/nfs/file.c
View File

@ -35,6 +35,7 @@
#include "delegation.h"
#include "internal.h"
#include "iostat.h"
#include "fscache.h"
#define NFSDBG_FACILITY NFSDBG_FILE
@ -409,6 +410,13 @@ static int nfs_write_end(struct file *file, struct address_space *mapping,
return copied;
}
/*
* Partially or wholly invalidate a page
* - Release the private state associated with a page if undergoing complete
* page invalidation
* - Called if either PG_private or PG_fscache is set on the page
* - Caller holds page lock
*/
static void nfs_invalidate_page(struct page *page, unsigned long offset)
{
dfprintk(PAGECACHE, "NFS: invalidate_page(%p, %lu)\n", page, offset);
@ -417,23 +425,43 @@ static void nfs_invalidate_page(struct page *page, unsigned long offset)
return;
/* Cancel any unstarted writes on this page */
nfs_wb_page_cancel(page->mapping->host, page);
nfs_fscache_invalidate_page(page, page->mapping->host);
}
/*
* Attempt to release the private state associated with a page
* - Called if either PG_private or PG_fscache is set on the page
* - Caller holds page lock
* - Return true (may release page) or false (may not)
*/
static int nfs_release_page(struct page *page, gfp_t gfp)
{
dfprintk(PAGECACHE, "NFS: release_page(%p)\n", page);
/* If PagePrivate() is set, then the page is not freeable */
return 0;
if (PagePrivate(page))
return 0;
return nfs_fscache_release_page(page, gfp);
}
/*
* Attempt to clear the private state associated with a page when an error
* occurs that requires the cached contents of an inode to be written back or
* destroyed
* - Called if either PG_private or fscache is set on the page
* - Caller holds page lock
* - Return 0 if successful, -error otherwise
*/
static int nfs_launder_page(struct page *page)
{
struct inode *inode = page->mapping->host;
struct nfs_inode *nfsi = NFS_I(inode);
dfprintk(PAGECACHE, "NFS: launder_page(%ld, %llu)\n",
inode->i_ino, (long long)page_offset(page));
nfs_fscache_wait_on_page_write(nfsi, page);
return nfs_wb_page(inode, page);
}
@ -451,6 +479,11 @@ const struct address_space_operations nfs_file_aops = {
.launder_page = nfs_launder_page,
};
/*
* Notification that a PTE pointing to an NFS page is about to be made
* writable, implying that someone is about to modify the page through a
* shared-writable mapping
*/
static int nfs_vm_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
{
struct page *page = vmf->page;
@ -465,6 +498,9 @@ static int nfs_vm_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
filp->f_mapping->host->i_ino,
(long long)page_offset(page));
/* make sure the cache has finished storing the page */
nfs_fscache_wait_on_page_write(NFS_I(dentry->d_inode), page);
lock_page(page);
mapping = page->mapping;
if (mapping != dentry->d_inode->i_mapping)

337
fs/nfs/fscache-index.c Normal file
View File

@ -0,0 +1,337 @@
/* NFS FS-Cache index structure definition
*
* Copyright (C) 2008 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public Licence
* as published by the Free Software Foundation; either version
* 2 of the Licence, or (at your option) any later version.
*/
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/nfs_fs.h>
#include <linux/nfs_fs_sb.h>
#include <linux/in6.h>
#include "internal.h"
#include "fscache.h"
#define NFSDBG_FACILITY NFSDBG_FSCACHE
/*
* Define the NFS filesystem for FS-Cache. Upon registration FS-Cache sticks
* the cookie for the top-level index object for NFS into here. The top-level
* index can than have other cache objects inserted into it.
*/
struct fscache_netfs nfs_fscache_netfs = {
.name = "nfs",
.version = 0,
};
/*
* Register NFS for caching
*/
int nfs_fscache_register(void)
{
return fscache_register_netfs(&nfs_fscache_netfs);
}
/*
* Unregister NFS for caching
*/
void nfs_fscache_unregister(void)
{
fscache_unregister_netfs(&nfs_fscache_netfs);
}
/*
* Layout of the key for an NFS server cache object.
*/
struct nfs_server_key {
uint16_t nfsversion; /* NFS protocol version */
uint16_t family; /* address family */
uint16_t port; /* IP port */
union {
struct in_addr ipv4_addr; /* IPv4 address */
struct in6_addr ipv6_addr; /* IPv6 address */
} addr[0];
};
/*
* Generate a key to describe a server in the main NFS index
* - We return the length of the key, or 0 if we can't generate one
*/
static uint16_t nfs_server_get_key(const void *cookie_netfs_data,
void *buffer, uint16_t bufmax)
{
const struct nfs_client *clp = cookie_netfs_data;
const struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *) &clp->cl_addr;
const struct sockaddr_in *sin = (struct sockaddr_in *) &clp->cl_addr;
struct nfs_server_key *key = buffer;
uint16_t len = sizeof(struct nfs_server_key);
key->nfsversion = clp->rpc_ops->version;
key->family = clp->cl_addr.ss_family;
memset(key, 0, len);
switch (clp->cl_addr.ss_family) {
case AF_INET:
key->port = sin->sin_port;
key->addr[0].ipv4_addr = sin->sin_addr;
len += sizeof(key->addr[0].ipv4_addr);
break;
case AF_INET6:
key->port = sin6->sin6_port;
key->addr[0].ipv6_addr = sin6->sin6_addr;
len += sizeof(key->addr[0].ipv6_addr);
break;
default:
printk(KERN_WARNING "NFS: Unknown network family '%d'\n",
clp->cl_addr.ss_family);
len = 0;
break;
}
return len;
}
/*
* Define the server object for FS-Cache. This is used to describe a server
* object to fscache_acquire_cookie(). It is keyed by the NFS protocol and
* server address parameters.
*/
const struct fscache_cookie_def nfs_fscache_server_index_def = {
.name = "NFS.server",
.type = FSCACHE_COOKIE_TYPE_INDEX,
.get_key = nfs_server_get_key,
};
/*
* Generate a key to describe a superblock key in the main NFS index
*/
static uint16_t nfs_super_get_key(const void *cookie_netfs_data,
void *buffer, uint16_t bufmax)
{
const struct nfs_fscache_key *key;
const struct nfs_server *nfss = cookie_netfs_data;
uint16_t len;
key = nfss->fscache_key;
len = sizeof(key->key) + key->key.uniq_len;
if (len > bufmax) {
len = 0;
} else {
memcpy(buffer, &key->key, sizeof(key->key));
memcpy(buffer + sizeof(key->key),
key->key.uniquifier, key->key.uniq_len);
}
return len;
}
/*
* Define the superblock object for FS-Cache. This is used to describe a
* superblock object to fscache_acquire_cookie(). It is keyed by all the NFS
* parameters that might cause a separate superblock.
*/
const struct fscache_cookie_def nfs_fscache_super_index_def = {
.name = "NFS.super",
.type = FSCACHE_COOKIE_TYPE_INDEX,
.get_key = nfs_super_get_key,
};
/*
* Definition of the auxiliary data attached to NFS inode storage objects
* within the cache.
*
* The contents of this struct are recorded in the on-disk local cache in the
* auxiliary data attached to the data storage object backing an inode. This
* permits coherency to be managed when a new inode binds to an already extant
* cache object.
*/
struct nfs_fscache_inode_auxdata {
struct timespec mtime;
struct timespec ctime;
loff_t size;
u64 change_attr;
};
/*
* Generate a key to describe an NFS inode in an NFS server's index
*/
static uint16_t nfs_fscache_inode_get_key(const void *cookie_netfs_data,
void *buffer, uint16_t bufmax)
{
const struct nfs_inode *nfsi = cookie_netfs_data;
uint16_t nsize;
/* use the inode's NFS filehandle as the key */
nsize = nfsi->fh.size;
memcpy(buffer, nfsi->fh.data, nsize);
return nsize;
}
/*
* Get certain file attributes from the netfs data
* - This function can be absent for an index
* - Not permitted to return an error
* - The netfs data from the cookie being used as the source is presented
*/
static void nfs_fscache_inode_get_attr(const void *cookie_netfs_data,
uint64_t *size)
{
const struct nfs_inode *nfsi = cookie_netfs_data;
*size = nfsi->vfs_inode.i_size;
}
/*
* Get the auxiliary data from netfs data
* - This function can be absent if the index carries no state data
* - Should store the auxiliary data in the buffer
* - Should return the amount of amount stored
* - Not permitted to return an error
* - The netfs data from the cookie being used as the source is presented
*/
static uint16_t nfs_fscache_inode_get_aux(const void *cookie_netfs_data,
void *buffer, uint16_t bufmax)
{
struct nfs_fscache_inode_auxdata auxdata;
const struct nfs_inode *nfsi = cookie_netfs_data;
memset(&auxdata, 0, sizeof(auxdata));
auxdata.size = nfsi->vfs_inode.i_size;
auxdata.mtime = nfsi->vfs_inode.i_mtime;
auxdata.ctime = nfsi->vfs_inode.i_ctime;
if (NFS_SERVER(&nfsi->vfs_inode)->nfs_client->rpc_ops->version == 4)
auxdata.change_attr = nfsi->change_attr;
if (bufmax > sizeof(auxdata))
bufmax = sizeof(auxdata);
memcpy(buffer, &auxdata, bufmax);
return bufmax;
}
/*
* Consult the netfs about the state of an object
* - This function can be absent if the index carries no state data
* - The netfs data from the cookie being used as the target is
* presented, as is the auxiliary data
*/
static
enum fscache_checkaux nfs_fscache_inode_check_aux(void *cookie_netfs_data,
const void *data,
uint16_t datalen)
{
struct nfs_fscache_inode_auxdata auxdata;
struct nfs_inode *nfsi = cookie_netfs_data;
if (datalen != sizeof(auxdata))
return FSCACHE_CHECKAUX_OBSOLETE;
memset(&auxdata, 0, sizeof(auxdata));
auxdata.size = nfsi->vfs_inode.i_size;
auxdata.mtime = nfsi->vfs_inode.i_mtime;
auxdata.ctime = nfsi->vfs_inode.i_ctime;
if (NFS_SERVER(&nfsi->vfs_inode)->nfs_client->rpc_ops->version == 4)
auxdata.change_attr = nfsi->change_attr;
if (memcmp(data, &auxdata, datalen) != 0)
return FSCACHE_CHECKAUX_OBSOLETE;
return FSCACHE_CHECKAUX_OKAY;
}
/*
* Indication from FS-Cache that the cookie is no longer cached
* - This function is called when the backing store currently caching a cookie
* is removed
* - The netfs should use this to clean up any markers indicating cached pages
* - This is mandatory for any object that may have data
*/
static void nfs_fscache_inode_now_uncached(void *cookie_netfs_data)
{
struct nfs_inode *nfsi = cookie_netfs_data;
struct pagevec pvec;
pgoff_t first;
int loop, nr_pages;
pagevec_init(&pvec, 0);
first = 0;
dprintk("NFS: nfs_inode_now_uncached: nfs_inode 0x%p\n", nfsi);
for (;;) {
/* grab a bunch of pages to unmark */
nr_pages = pagevec_lookup(&pvec,
nfsi->vfs_inode.i_mapping,
first,
PAGEVEC_SIZE - pagevec_count(&pvec));
if (!nr_pages)
break;
for (loop = 0; loop < nr_pages; loop++)
ClearPageFsCache(pvec.pages[loop]);
first = pvec.pages[nr_pages - 1]->index + 1;
pvec.nr = nr_pages;
pagevec_release(&pvec);
cond_resched();
}
}
/*
* Get an extra reference on a read context.
* - This function can be absent if the completion function doesn't require a
* context.
* - The read context is passed back to NFS in the event that a data read on the
* cache fails with EIO - in which case the server must be contacted to
* retrieve the data, which requires the read context for security.
*/
static void nfs_fh_get_context(void *cookie_netfs_data, void *context)
{
get_nfs_open_context(context);
}
/*
* Release an extra reference on a read context.
* - This function can be absent if the completion function doesn't require a
* context.
*/
static void nfs_fh_put_context(void *cookie_netfs_data, void *context)
{
if (context)
put_nfs_open_context(context);
}
/*
* Define the inode object for FS-Cache. This is used to describe an inode
* object to fscache_acquire_cookie(). It is keyed by the NFS file handle for
* an inode.
*
* Coherency is managed by comparing the copies of i_size, i_mtime and i_ctime
* held in the cache auxiliary data for the data storage object with those in
* the inode struct in memory.
*/
const struct fscache_cookie_def nfs_fscache_inode_object_def = {
.name = "NFS.fh",
.type = FSCACHE_COOKIE_TYPE_DATAFILE,
.get_key = nfs_fscache_inode_get_key,
.get_attr = nfs_fscache_inode_get_attr,
.get_aux = nfs_fscache_inode_get_aux,
.check_aux = nfs_fscache_inode_check_aux,
.now_uncached = nfs_fscache_inode_now_uncached,
.get_context = nfs_fh_get_context,
.put_context = nfs_fh_put_context,
};

523
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/* NFS filesystem cache interface
*
* Copyright (C) 2008 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public Licence
* as published by the Free Software Foundation; either version
* 2 of the Licence, or (at your option) any later version.
*/
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/nfs_fs.h>
#include <linux/nfs_fs_sb.h>
#include <linux/in6.h>
#include <linux/seq_file.h>
#include "internal.h"
#include "iostat.h"
#include "fscache.h"
#define NFSDBG_FACILITY NFSDBG_FSCACHE
static struct rb_root nfs_fscache_keys = RB_ROOT;
static DEFINE_SPINLOCK(nfs_fscache_keys_lock);
/*
* Get the per-client index cookie for an NFS client if the appropriate mount
* flag was set
* - We always try and get an index cookie for the client, but get filehandle
* cookies on a per-superblock basis, depending on the mount flags
*/
void nfs_fscache_get_client_cookie(struct nfs_client *clp)
{
/* create a cache index for looking up filehandles */
clp->fscache = fscache_acquire_cookie(nfs_fscache_netfs.primary_index,
&nfs_fscache_server_index_def,
clp);
dfprintk(FSCACHE, "NFS: get client cookie (0x%p/0x%p)\n",
clp, clp->fscache);
}
/*
* Dispose of a per-client cookie
*/
void nfs_fscache_release_client_cookie(struct nfs_client *clp)
{
dfprintk(FSCACHE, "NFS: releasing client cookie (0x%p/0x%p)\n",
clp, clp->fscache);
fscache_relinquish_cookie(clp->fscache, 0);
clp->fscache = NULL;
}
/*
* Get the cache cookie for an NFS superblock. We have to handle
* uniquification here because the cache doesn't do it for us.
*/
void nfs_fscache_get_super_cookie(struct super_block *sb,
struct nfs_parsed_mount_data *data)
{
struct nfs_fscache_key *key, *xkey;
struct nfs_server *nfss = NFS_SB(sb);
struct rb_node **p, *parent;
const char *uniq = data->fscache_uniq ?: "";
int diff, ulen;
ulen = strlen(uniq);
key = kzalloc(sizeof(*key) + ulen, GFP_KERNEL);
if (!key)
return;
key->nfs_client = nfss->nfs_client;
key->key.super.s_flags = sb->s_flags & NFS_MS_MASK;
key->key.nfs_server.flags = nfss->flags;
key->key.nfs_server.rsize = nfss->rsize;
key->key.nfs_server.wsize = nfss->wsize;
key->key.nfs_server.acregmin = nfss->acregmin;
key->key.nfs_server.acregmax = nfss->acregmax;
key->key.nfs_server.acdirmin = nfss->acdirmin;
key->key.nfs_server.acdirmax = nfss->acdirmax;
key->key.nfs_server.fsid = nfss->fsid;
key->key.rpc_auth.au_flavor = nfss->client->cl_auth->au_flavor;
key->key.uniq_len = ulen;
memcpy(key->key.uniquifier, uniq, ulen);
spin_lock(&nfs_fscache_keys_lock);
p = &nfs_fscache_keys.rb_node;
parent = NULL;
while (*p) {
parent = *p;
xkey = rb_entry(parent, struct nfs_fscache_key, node);
if (key->nfs_client < xkey->nfs_client)
goto go_left;
if (key->nfs_client > xkey->nfs_client)
goto go_right;
diff = memcmp(&key->key, &xkey->key, sizeof(key->key));
if (diff < 0)
goto go_left;
if (diff > 0)
goto go_right;
if (key->key.uniq_len == 0)
goto non_unique;
diff = memcmp(key->key.uniquifier,
xkey->key.uniquifier,
key->key.uniq_len);
if (diff < 0)
goto go_left;
if (diff > 0)
goto go_right;
goto non_unique;
go_left:
p = &(*p)->rb_left;
continue;
go_right:
p = &(*p)->rb_right;
}
rb_link_node(&key->node, parent, p);
rb_insert_color(&key->node, &nfs_fscache_keys);
spin_unlock(&nfs_fscache_keys_lock);
nfss->fscache_key = key;
/* create a cache index for looking up filehandles */
nfss->fscache = fscache_acquire_cookie(nfss->nfs_client->fscache,
&nfs_fscache_super_index_def,
nfss);
dfprintk(FSCACHE, "NFS: get superblock cookie (0x%p/0x%p)\n",
nfss, nfss->fscache);
return;
non_unique:
spin_unlock(&nfs_fscache_keys_lock);
kfree(key);
nfss->fscache_key = NULL;
nfss->fscache = NULL;
printk(KERN_WARNING "NFS:"
" Cache request denied due to non-unique superblock keys\n");
}
/*
* release a per-superblock cookie
*/
void nfs_fscache_release_super_cookie(struct super_block *sb)
{
struct nfs_server *nfss = NFS_SB(sb);
dfprintk(FSCACHE, "NFS: releasing superblock cookie (0x%p/0x%p)\n",
nfss, nfss->fscache);
fscache_relinquish_cookie(nfss->fscache, 0);
nfss->fscache = NULL;
if (nfss->fscache_key) {
spin_lock(&nfs_fscache_keys_lock);
rb_erase(&nfss->fscache_key->node, &nfs_fscache_keys);
spin_unlock(&nfs_fscache_keys_lock);
kfree(nfss->fscache_key);
nfss->fscache_key = NULL;
}
}
/*
* Initialise the per-inode cache cookie pointer for an NFS inode.
*/
void nfs_fscache_init_inode_cookie(struct inode *inode)
{
NFS_I(inode)->fscache = NULL;
if (S_ISREG(inode->i_mode))
set_bit(NFS_INO_FSCACHE, &NFS_I(inode)->flags);
}
/*
* Get the per-inode cache cookie for an NFS inode.
*/
static void nfs_fscache_enable_inode_cookie(struct inode *inode)
{
struct super_block *sb = inode->i_sb;
struct nfs_inode *nfsi = NFS_I(inode);
if (nfsi->fscache || !NFS_FSCACHE(inode))
return;
if ((NFS_SB(sb)->options & NFS_OPTION_FSCACHE)) {
nfsi->fscache = fscache_acquire_cookie(
NFS_SB(sb)->fscache,
&nfs_fscache_inode_object_def,
nfsi);
dfprintk(FSCACHE, "NFS: get FH cookie (0x%p/0x%p/0x%p)\n",
sb, nfsi, nfsi->fscache);
}
}
/*
* Release a per-inode cookie.
*/
void nfs_fscache_release_inode_cookie(struct inode *inode)
{
struct nfs_inode *nfsi = NFS_I(inode);
dfprintk(FSCACHE, "NFS: clear cookie (0x%p/0x%p)\n",
nfsi, nfsi->fscache);
fscache_relinquish_cookie(nfsi->fscache, 0);
nfsi->fscache = NULL;
}
/*
* Retire a per-inode cookie, destroying the data attached to it.
*/
void nfs_fscache_zap_inode_cookie(struct inode *inode)
{
struct nfs_inode *nfsi = NFS_I(inode);
dfprintk(FSCACHE, "NFS: zapping cookie (0x%p/0x%p)\n",
nfsi, nfsi->fscache);
fscache_relinquish_cookie(nfsi->fscache, 1);
nfsi->fscache = NULL;
}
/*
* Turn off the cache with regard to a per-inode cookie if opened for writing,
* invalidating all the pages in the page cache relating to the associated
* inode to clear the per-page caching.
*/
static void nfs_fscache_disable_inode_cookie(struct inode *inode)
{
clear_bit(NFS_INO_FSCACHE, &NFS_I(inode)->flags);
if (NFS_I(inode)->fscache) {
dfprintk(FSCACHE,
"NFS: nfsi 0x%p turning cache off\n", NFS_I(inode));
/* Need to invalidate any mapped pages that were read in before
* turning off the cache.
*/
if (inode->i_mapping && inode->i_mapping->nrpages)
invalidate_inode_pages2(inode->i_mapping);
nfs_fscache_zap_inode_cookie(inode);
}
}
/*
* wait_on_bit() sleep function for uninterruptible waiting
*/
static int nfs_fscache_wait_bit(void *flags)
{
schedule();
return 0;
}
/*
* Lock against someone else trying to also acquire or relinquish a cookie
*/
static inline void nfs_fscache_inode_lock(struct inode *inode)
{
struct nfs_inode *nfsi = NFS_I(inode);
while (test_and_set_bit(NFS_INO_FSCACHE_LOCK, &nfsi->flags))
wait_on_bit(&nfsi->flags, NFS_INO_FSCACHE_LOCK,
nfs_fscache_wait_bit, TASK_UNINTERRUPTIBLE);
}
/*
* Unlock cookie management lock
*/
static inline void nfs_fscache_inode_unlock(struct inode *inode)
{
struct nfs_inode *nfsi = NFS_I(inode);
smp_mb__before_clear_bit();
clear_bit(NFS_INO_FSCACHE_LOCK, &nfsi->flags);
smp_mb__after_clear_bit();
wake_up_bit(&nfsi->flags, NFS_INO_FSCACHE_LOCK);
}
/*
* Decide if we should enable or disable local caching for this inode.
* - For now, with NFS, only regular files that are open read-only will be able
* to use the cache.
* - May be invoked multiple times in parallel by parallel nfs_open() functions.
*/
void nfs_fscache_set_inode_cookie(struct inode *inode, struct file *filp)
{
if (NFS_FSCACHE(inode)) {
nfs_fscache_inode_lock(inode);
if ((filp->f_flags & O_ACCMODE) != O_RDONLY)
nfs_fscache_disable_inode_cookie(inode);
else
nfs_fscache_enable_inode_cookie(inode);
nfs_fscache_inode_unlock(inode);
}
}
/*
* Replace a per-inode cookie due to revalidation detecting a file having
* changed on the server.
*/
void nfs_fscache_reset_inode_cookie(struct inode *inode)
{
struct nfs_inode *nfsi = NFS_I(inode);
struct nfs_server *nfss = NFS_SERVER(inode);
struct fscache_cookie *old = nfsi->fscache;
nfs_fscache_inode_lock(inode);
if (nfsi->fscache) {
/* retire the current fscache cache and get a new one */
fscache_relinquish_cookie(nfsi->fscache, 1);
nfsi->fscache = fscache_acquire_cookie(
nfss->nfs_client->fscache,
&nfs_fscache_inode_object_def,
nfsi);
dfprintk(FSCACHE,
"NFS: revalidation new cookie (0x%p/0x%p/0x%p/0x%p)\n",
nfss, nfsi, old, nfsi->fscache);
}
nfs_fscache_inode_unlock(inode);
}
/*
* Release the caching state associated with a page, if the page isn't busy
* interacting with the cache.
* - Returns true (can release page) or false (page busy).
*/
int nfs_fscache_release_page(struct page *page, gfp_t gfp)
{
struct nfs_inode *nfsi = NFS_I(page->mapping->host);
struct fscache_cookie *cookie = nfsi->fscache;
BUG_ON(!cookie);
if (fscache_check_page_write(cookie, page)) {
if (!(gfp & __GFP_WAIT))
return 0;
fscache_wait_on_page_write(cookie, page);
}
if (PageFsCache(page)) {
dfprintk(FSCACHE, "NFS: fscache releasepage (0x%p/0x%p/0x%p)\n",
cookie, page, nfsi);
fscache_uncache_page(cookie, page);
nfs_add_fscache_stats(page->mapping->host,
NFSIOS_FSCACHE_PAGES_UNCACHED, 1);
}
return 1;
}
/*
* Release the caching state associated with a page if undergoing complete page
* invalidation.
*/
void __nfs_fscache_invalidate_page(struct page *page, struct inode *inode)
{
struct nfs_inode *nfsi = NFS_I(inode);
struct fscache_cookie *cookie = nfsi->fscache;
BUG_ON(!cookie);
dfprintk(FSCACHE, "NFS: fscache invalidatepage (0x%p/0x%p/0x%p)\n",
cookie, page, nfsi);
fscache_wait_on_page_write(cookie, page);
BUG_ON(!PageLocked(page));
fscache_uncache_page(cookie, page);
nfs_add_fscache_stats(page->mapping->host,
NFSIOS_FSCACHE_PAGES_UNCACHED, 1);
}
/*
* Handle completion of a page being read from the cache.
* - Called in process (keventd) context.
*/
static void nfs_readpage_from_fscache_complete(struct page *page,
void *context,
int error)
{
dfprintk(FSCACHE,
"NFS: readpage_from_fscache_complete (0x%p/0x%p/%d)\n",
page, context, error);
/* if the read completes with an error, we just unlock the page and let
* the VM reissue the readpage */
if (!error) {
SetPageUptodate(page);
unlock_page(page);
} else {
error = nfs_readpage_async(context, page->mapping->host, page);
if (error)
unlock_page(page);
}
}
/*
* Retrieve a page from fscache
*/
int __nfs_readpage_from_fscache(struct nfs_open_context *ctx,
struct inode *inode, struct page *page)
{
int ret;
dfprintk(FSCACHE,
"NFS: readpage_from_fscache(fsc:%p/p:%p(i:%lx f:%lx)/0x%p)\n",
NFS_I(inode)->fscache, page, page->index, page->flags, inode);
ret = fscache_read_or_alloc_page(NFS_I(inode)->fscache,
page,
nfs_readpage_from_fscache_complete,
ctx,
GFP_KERNEL);
switch (ret) {
case 0: /* read BIO submitted (page in fscache) */
dfprintk(FSCACHE,
"NFS: readpage_from_fscache: BIO submitted\n");
nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_OK, 1);
return ret;
case -ENOBUFS: /* inode not in cache */
case -ENODATA: /* page not in cache */
nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_FAIL, 1);
dfprintk(FSCACHE,
"NFS: readpage_from_fscache %d\n", ret);
return 1;
default:
dfprintk(FSCACHE, "NFS: readpage_from_fscache %d\n", ret);
nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_FAIL, 1);
}
return ret;
}
/*
* Retrieve a set of pages from fscache
*/
int __nfs_readpages_from_fscache(struct nfs_open_context *ctx,
struct inode *inode,
struct address_space *mapping,
struct list_head *pages,
unsigned *nr_pages)
{
int ret, npages = *nr_pages;
dfprintk(FSCACHE, "NFS: nfs_getpages_from_fscache (0x%p/%u/0x%p)\n",
NFS_I(inode)->fscache, npages, inode);
ret = fscache_read_or_alloc_pages(NFS_I(inode)->fscache,
mapping, pages, nr_pages,
nfs_readpage_from_fscache_complete,
ctx,
mapping_gfp_mask(mapping));
if (*nr_pages < npages)
nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_OK,
npages);
if (*nr_pages > 0)
nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_FAIL,
*nr_pages);
switch (ret) {
case 0: /* read submitted to the cache for all pages */
BUG_ON(!list_empty(pages));
BUG_ON(*nr_pages != 0);
dfprintk(FSCACHE,
"NFS: nfs_getpages_from_fscache: submitted\n");
return ret;
case -ENOBUFS: /* some pages aren't cached and can't be */
case -ENODATA: /* some pages aren't cached */
dfprintk(FSCACHE,
"NFS: nfs_getpages_from_fscache: no page: %d\n", ret);
return 1;
default:
dfprintk(FSCACHE,
"NFS: nfs_getpages_from_fscache: ret %d\n", ret);
}
return ret;
}
/*
* Store a newly fetched page in fscache
* - PG_fscache must be set on the page
*/
void __nfs_readpage_to_fscache(struct inode *inode, struct page *page, int sync)
{
int ret;
dfprintk(FSCACHE,
"NFS: readpage_to_fscache(fsc:%p/p:%p(i:%lx f:%lx)/%d)\n",
NFS_I(inode)->fscache, page, page->index, page->flags, sync);
ret = fscache_write_page(NFS_I(inode)->fscache, page, GFP_KERNEL);
dfprintk(FSCACHE,
"NFS: readpage_to_fscache: p:%p(i:%lu f:%lx) ret %d\n",
page, page->index, page->flags, ret);
if (ret != 0) {
fscache_uncache_page(NFS_I(inode)->fscache, page);
nfs_add_fscache_stats(inode,
NFSIOS_FSCACHE_PAGES_WRITTEN_FAIL, 1);
nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_UNCACHED, 1);
} else {
nfs_add_fscache_stats(inode,
NFSIOS_FSCACHE_PAGES_WRITTEN_OK, 1);
}
}

220
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/* NFS filesystem cache interface definitions
*
* Copyright (C) 2008 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public Licence
* as published by the Free Software Foundation; either version
* 2 of the Licence, or (at your option) any later version.
*/
#ifndef _NFS_FSCACHE_H
#define _NFS_FSCACHE_H
#include <linux/nfs_fs.h>
#include <linux/nfs_mount.h>
#include <linux/nfs4_mount.h>
#include <linux/fscache.h>
#ifdef CONFIG_NFS_FSCACHE
/*
* set of NFS FS-Cache objects that form a superblock key
*/
struct nfs_fscache_key {
struct rb_node node;
struct nfs_client *nfs_client; /* the server */
/* the elements of the unique key - as used by nfs_compare_super() and
* nfs_compare_mount_options() to distinguish superblocks */
struct {
struct {
unsigned long s_flags; /* various flags
* (& NFS_MS_MASK) */
} super;
struct {
struct nfs_fsid fsid;
int flags;
unsigned int rsize; /* read size */
unsigned int wsize; /* write size */
unsigned int acregmin; /* attr cache timeouts */
unsigned int acregmax;
unsigned int acdirmin;
unsigned int acdirmax;
} nfs_server;
struct {
rpc_authflavor_t au_flavor;
} rpc_auth;
/* uniquifier - can be used if nfs_server.flags includes
* NFS_MOUNT_UNSHARED */
u8 uniq_len;
char uniquifier[0];
} key;
};
/*
* fscache-index.c
*/
extern struct fscache_netfs nfs_fscache_netfs;
extern const struct fscache_cookie_def nfs_fscache_server_index_def;
extern const struct fscache_cookie_def nfs_fscache_super_index_def;
extern const struct fscache_cookie_def nfs_fscache_inode_object_def;
extern int nfs_fscache_register(void);
extern void nfs_fscache_unregister(void);
/*
* fscache.c
*/
extern void nfs_fscache_get_client_cookie(struct nfs_client *);
extern void nfs_fscache_release_client_cookie(struct nfs_client *);
extern void nfs_fscache_get_super_cookie(struct super_block *,
struct nfs_parsed_mount_data *);
extern void nfs_fscache_release_super_cookie(struct super_block *);
extern void nfs_fscache_init_inode_cookie(struct inode *);
extern void nfs_fscache_release_inode_cookie(struct inode *);
extern void nfs_fscache_zap_inode_cookie(struct inode *);
extern void nfs_fscache_set_inode_cookie(struct inode *, struct file *);
extern void nfs_fscache_reset_inode_cookie(struct inode *);
extern void __nfs_fscache_invalidate_page(struct page *, struct inode *);
extern int nfs_fscache_release_page(struct page *, gfp_t);
extern int __nfs_readpage_from_fscache(struct nfs_open_context *,
struct inode *, struct page *);
extern int __nfs_readpages_from_fscache(struct nfs_open_context *,
struct inode *, struct address_space *,
struct list_head *, unsigned *);
extern void __nfs_readpage_to_fscache(struct inode *, struct page *, int);
/*
* wait for a page to complete writing to the cache
*/
static inline void nfs_fscache_wait_on_page_write(struct nfs_inode *nfsi,
struct page *page)
{
if (PageFsCache(page))
fscache_wait_on_page_write(nfsi->fscache, page);
}
/*
* release the caching state associated with a page if undergoing complete page
* invalidation
*/
static inline void nfs_fscache_invalidate_page(struct page *page,
struct inode *inode)
{
if (PageFsCache(page))
__nfs_fscache_invalidate_page(page, inode);
}
/*
* Retrieve a page from an inode data storage object.
*/
static inline int nfs_readpage_from_fscache(struct nfs_open_context *ctx,
struct inode *inode,
struct page *page)
{
if (NFS_I(inode)->fscache)
return __nfs_readpage_from_fscache(ctx, inode, page);
return -ENOBUFS;
}
/*
* Retrieve a set of pages from an inode data storage object.
*/
static inline int nfs_readpages_from_fscache(struct nfs_open_context *ctx,
struct inode *inode,
struct address_space *mapping,
struct list_head *pages,
unsigned *nr_pages)
{
if (NFS_I(inode)->fscache)
return __nfs_readpages_from_fscache(ctx, inode, mapping, pages,
nr_pages);
return -ENOBUFS;
}
/*
* Store a page newly fetched from the server in an inode data storage object
* in the cache.
*/
static inline void nfs_readpage_to_fscache(struct inode *inode,
struct page *page,
int sync)
{
if (PageFsCache(page))
__nfs_readpage_to_fscache(inode, page, sync);
}
/*
* indicate the client caching state as readable text
*/
static inline const char *nfs_server_fscache_state(struct nfs_server *server)
{
if (server->fscache && (server->options & NFS_OPTION_FSCACHE))
return "yes";
return "no ";
}
#else /* CONFIG_NFS_FSCACHE */
static inline int nfs_fscache_register(void) { return 0; }
static inline void nfs_fscache_unregister(void) {}
static inline void nfs_fscache_get_client_cookie(struct nfs_client *clp) {}
static inline void nfs_fscache_release_client_cookie(struct nfs_client *clp) {}
static inline void nfs_fscache_get_super_cookie(
struct super_block *sb,
struct nfs_parsed_mount_data *data)
{
}
static inline void nfs_fscache_release_super_cookie(struct super_block *sb) {}
static inline void nfs_fscache_init_inode_cookie(struct inode *inode) {}
static inline void nfs_fscache_release_inode_cookie(struct inode *inode) {}
static inline void nfs_fscache_zap_inode_cookie(struct inode *inode) {}
static inline void nfs_fscache_set_inode_cookie(struct inode *inode,
struct file *filp) {}
static inline void nfs_fscache_reset_inode_cookie(struct inode *inode) {}
static inline int nfs_fscache_release_page(struct page *page, gfp_t gfp)
{
return 1; /* True: may release page */
}
static inline void nfs_fscache_invalidate_page(struct page *page,
struct inode *inode) {}
static inline void nfs_fscache_wait_on_page_write(struct nfs_inode *nfsi,
struct page *page) {}
static inline int nfs_readpage_from_fscache(struct nfs_open_context *ctx,
struct inode *inode,
struct page *page)
{
return -ENOBUFS;
}
static inline int nfs_readpages_from_fscache(struct nfs_open_context *ctx,
struct inode *inode,
struct address_space *mapping,
struct list_head *pages,
unsigned *nr_pages)
{
return -ENOBUFS;
}
static inline void nfs_readpage_to_fscache(struct inode *inode,
struct page *page, int sync) {}
static inline const char *nfs_server_fscache_state(struct nfs_server *server)
{
return "no ";
}
#endif /* CONFIG_NFS_FSCACHE */
#endif /* _NFS_FSCACHE_H */

14
fs/nfs/inode.c
View File

@ -46,6 +46,7 @@
#include "delegation.h"
#include "iostat.h"
#include "internal.h"
#include "fscache.h"
#define NFSDBG_FACILITY NFSDBG_VFS
@ -121,6 +122,7 @@ void nfs_clear_inode(struct inode *inode)
BUG_ON(!list_empty(&NFS_I(inode)->open_files));
nfs_zap_acl_cache(inode);
nfs_access_zap_cache(inode);
nfs_fscache_release_inode_cookie(inode);
}
/**
@ -355,6 +357,8 @@ nfs_fhget(struct super_block *sb, struct nfs_fh *fh, struct nfs_fattr *fattr)
nfsi->attrtimeo_timestamp = now;
nfsi->access_cache = RB_ROOT;
nfs_fscache_init_inode_cookie(inode);
unlock_new_inode(inode);
} else
nfs_refresh_inode(inode, fattr);
@ -686,6 +690,7 @@ int nfs_open(struct inode *inode, struct file *filp)
ctx->mode = filp->f_mode;
nfs_file_set_open_context(filp, ctx);
put_nfs_open_context(ctx);
nfs_fscache_set_inode_cookie(inode, filp);
return 0;
}
@ -786,6 +791,7 @@ static int nfs_invalidate_mapping_nolock(struct inode *inode, struct address_spa
memset(nfsi->cookieverf, 0, sizeof(nfsi->cookieverf));
spin_unlock(&inode->i_lock);
nfs_inc_stats(inode, NFSIOS_DATAINVALIDATE);
nfs_fscache_reset_inode_cookie(inode);
dfprintk(PAGECACHE, "NFS: (%s/%Ld) data cache invalidated\n",
inode->i_sb->s_id, (long long)NFS_FILEID(inode));
return 0;
@ -1030,6 +1036,7 @@ int nfs_refresh_inode(struct inode *inode, struct nfs_fattr *fattr)
spin_lock(&inode->i_lock);
status = nfs_refresh_inode_locked(inode, fattr);
spin_unlock(&inode->i_lock);
return status;
}
@ -1436,6 +1443,10 @@ static int __init init_nfs_fs(void)
{
int err;
err = nfs_fscache_register();
if (err < 0)
goto out7;
err = nfsiod_start();
if (err)
goto out6;
@ -1488,6 +1499,8 @@ static int __init init_nfs_fs(void)
out5:
nfsiod_stop();
out6:
nfs_fscache_unregister();
out7:
return err;
}
@ -1498,6 +1511,7 @@ static void __exit exit_nfs_fs(void)
nfs_destroy_readpagecache();
nfs_destroy_inodecache();
nfs_destroy_nfspagecache();
nfs_fscache_unregister();
#ifdef CONFIG_PROC_FS
rpc_proc_unregister("nfs");
#endif

4
fs/nfs/internal.h
View File

@ -5,6 +5,8 @@
#include <linux/mount.h>
#include <linux/security.h>
#define NFS_MS_MASK (MS_RDONLY|MS_NOSUID|MS_NODEV|MS_NOEXEC|MS_SYNCHRONOUS)
struct nfs_string;
/* Maximum number of readahead requests
@ -37,10 +39,12 @@ struct nfs_parsed_mount_data {
int acregmin, acregmax,
acdirmin, acdirmax;
int namlen;
unsigned int options;
unsigned int bsize;
unsigned int auth_flavor_len;
rpc_authflavor_t auth_flavors[1];
char *client_address;
char *fscache_uniq;
struct {
struct sockaddr_storage address;

18
fs/nfs/iostat.h
View File

@ -16,6 +16,9 @@
struct nfs_iostats {
unsigned long long bytes[__NFSIOS_BYTESMAX];
#ifdef CONFIG_NFS_FSCACHE
unsigned long long fscache[__NFSIOS_FSCACHEMAX];
#endif
unsigned long events[__NFSIOS_COUNTSMAX];
} ____cacheline_aligned;
@ -57,6 +60,21 @@ static inline void nfs_add_stats(const struct inode *inode,
nfs_add_server_stats(NFS_SERVER(inode), stat, addend);
}
#ifdef CONFIG_NFS_FSCACHE
static inline void nfs_add_fscache_stats(struct inode *inode,
enum nfs_stat_fscachecounters stat,
unsigned long addend)
{
struct nfs_iostats *iostats;
int cpu;
cpu = get_cpu();
iostats = per_cpu_ptr(NFS_SERVER(inode)->io_stats, cpu);
iostats->fscache[stat] += addend;
put_cpu_no_resched();
}
#endif
static inline struct nfs_iostats *nfs_alloc_iostats(void)
{
return alloc_percpu(struct nfs_iostats);

27
fs/nfs/read.c
View File

@ -24,6 +24,7 @@
#include "internal.h"
#include "iostat.h"
#include "fscache.h"
#define NFSDBG_FACILITY NFSDBG_PAGECACHE
@ -111,8 +112,8 @@ static void nfs_readpage_truncate_uninitialised_page(struct nfs_read_data *data)
}
}
static int nfs_readpage_async(struct nfs_open_context *ctx, struct inode *inode,
struct page *page)
int nfs_readpage_async(struct nfs_open_context *ctx, struct inode *inode,
struct page *page)
{
LIST_HEAD(one_request);
struct nfs_page *new;
@ -139,6 +140,11 @@ static int nfs_readpage_async(struct nfs_open_context *ctx, struct inode *inode,
static void nfs_readpage_release(struct nfs_page *req)
{
struct inode *d_inode = req->wb_context->path.dentry->d_inode;
if (PageUptodate(req->wb_page))
nfs_readpage_to_fscache(d_inode, req->wb_page, 0);
unlock_page(req->wb_page);
dprintk("NFS: read done (%s/%Ld %d@%Ld)\n",
@ -510,8 +516,15 @@ int nfs_readpage(struct file *file, struct page *page)
} else
ctx = get_nfs_open_context(nfs_file_open_context(file));
if (!IS_SYNC(inode)) {
error = nfs_readpage_from_fscache(ctx, inode, page);
if (error == 0)
goto out;
}
error = nfs_readpage_async(ctx, inode, page);
out:
put_nfs_open_context(ctx);
return error;
out_unlock:
@ -584,6 +597,15 @@ int nfs_readpages(struct file *filp, struct address_space *mapping,
return -EBADF;
} else
desc.ctx = get_nfs_open_context(nfs_file_open_context(filp));
/* attempt to read as many of the pages as possible from the cache
* - this returns -ENOBUFS immediately if the cookie is negative
*/
ret = nfs_readpages_from_fscache(desc.ctx, inode, mapping,
pages, &nr_pages);
if (ret == 0)
goto read_complete; /* all pages were read */
if (rsize < PAGE_CACHE_SIZE)
nfs_pageio_init(&pgio, inode, nfs_pagein_multi, rsize, 0);
else
@ -594,6 +616,7 @@ int nfs_readpages(struct file *filp, struct address_space *mapping,
nfs_pageio_complete(&pgio);
npages = (pgio.pg_bytes_written + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
nfs_add_stats(inode, NFSIOS_READPAGES, npages);
read_complete:
put_nfs_open_context(desc.ctx);
out:
return ret;

45
fs/nfs/super.c
View File

@ -60,6 +60,7 @@
#include "delegation.h"
#include "iostat.h"
#include "internal.h"
#include "fscache.h"
#define NFSDBG_FACILITY NFSDBG_VFS
@ -76,6 +77,7 @@ enum {
Opt_rdirplus, Opt_nordirplus,
Opt_sharecache, Opt_nosharecache,
Opt_resvport, Opt_noresvport,
Opt_fscache, Opt_nofscache,
/* Mount options that take integer arguments */
Opt_port,
@ -93,6 +95,7 @@ enum {
Opt_sec, Opt_proto, Opt_mountproto, Opt_mounthost,
Opt_addr, Opt_mountaddr, Opt_clientaddr,
Opt_lookupcache,
Opt_fscache_uniq,
/* Special mount options */
Opt_userspace, Opt_deprecated, Opt_sloppy,
@ -132,6 +135,9 @@ static const match_table_t nfs_mount_option_tokens = {
{ Opt_nosharecache, "nosharecache" },
{ Opt_resvport, "resvport" },
{ Opt_noresvport, "noresvport" },
{ Opt_fscache, "fsc" },
{ Opt_fscache_uniq, "fsc=%s" },
{ Opt_nofscache, "nofsc" },
{ Opt_port, "port=%u" },
{ Opt_rsize, "rsize=%u" },
@ -563,6 +569,8 @@ static void nfs_show_mount_options(struct seq_file *m, struct nfs_server *nfss,
if (clp->rpc_ops->version == 4)
seq_printf(m, ",clientaddr=%s", clp->cl_ipaddr);
#endif
if (nfss->options & NFS_OPTION_FSCACHE)
seq_printf(m, ",fsc");
}
/*
@ -641,6 +649,10 @@ static int nfs_show_stats(struct seq_file *m, struct vfsmount *mnt)
totals.events[i] += stats->events[i];
for (i = 0; i < __NFSIOS_BYTESMAX; i++)
totals.bytes[i] += stats->bytes[i];
#ifdef CONFIG_NFS_FSCACHE
for (i = 0; i < __NFSIOS_FSCACHEMAX; i++)
totals.fscache[i] += stats->fscache[i];
#endif
preempt_enable();
}
@ -651,6 +663,13 @@ static int nfs_show_stats(struct seq_file *m, struct vfsmount *mnt)
seq_printf(m, "\n\tbytes:\t");
for (i = 0; i < __NFSIOS_BYTESMAX; i++)
seq_printf(m, "%Lu ", totals.bytes[i]);
#ifdef CONFIG_NFS_FSCACHE
if (nfss->options & NFS_OPTION_FSCACHE) {
seq_printf(m, "\n\tfsc:\t");
for (i = 0; i < __NFSIOS_FSCACHEMAX; i++)
seq_printf(m, "%Lu ", totals.bytes[i]);
}
#endif
seq_printf(m, "\n");
rpc_print_iostats(m, nfss->client);
@ -1044,6 +1063,24 @@ static int nfs_parse_mount_options(char *raw,
case Opt_noresvport:
mnt->flags |= NFS_MOUNT_NORESVPORT;
break;
case Opt_fscache:
mnt->options |= NFS_OPTION_FSCACHE;
kfree(mnt->fscache_uniq);
mnt->fscache_uniq = NULL;
break;
case Opt_nofscache:
mnt->options &= ~NFS_OPTION_FSCACHE;
kfree(mnt->fscache_uniq);
mnt->fscache_uniq = NULL;
break;
case Opt_fscache_uniq:
string = match_strdup(args);
if (!string)
goto out_nomem;
kfree(mnt->fscache_uniq);
mnt->fscache_uniq = string;
mnt->options |= NFS_OPTION_FSCACHE;
break;
/*
* options that take numeric values
@ -1870,8 +1907,6 @@ static void nfs_clone_super(struct super_block *sb,
nfs_initialise_sb(sb);
}
#define NFS_MS_MASK (MS_RDONLY|MS_NOSUID|MS_NODEV|MS_NOEXEC|MS_SYNCHRONOUS)
static int nfs_compare_mount_options(const struct super_block *s, const struct nfs_server *b, int flags)
{
const struct nfs_server *a = s->s_fs_info;
@ -2036,6 +2071,7 @@ static int nfs_get_sb(struct file_system_type *fs_type,
if (!s->s_root) {
/* initial superblock/root creation */
nfs_fill_super(s, data);
nfs_fscache_get_super_cookie(s, data);
}
mntroot = nfs_get_root(s, mntfh);
@ -2056,6 +2092,7 @@ static int nfs_get_sb(struct file_system_type *fs_type,
out:
kfree(data->nfs_server.hostname);
kfree(data->mount_server.hostname);
kfree(data->fscache_uniq);
security_free_mnt_opts(&data->lsm_opts);
out_free_fh:
kfree(mntfh);
@ -2083,6 +2120,7 @@ static void nfs_kill_super(struct super_block *s)
bdi_unregister(&server->backing_dev_info);
kill_anon_super(s);
nfs_fscache_release_super_cookie(s);
nfs_free_server(server);
}
@ -2390,6 +2428,7 @@ static int nfs4_get_sb(struct file_system_type *fs_type,
if (!s->s_root) {
/* initial superblock/root creation */
nfs4_fill_super(s);
nfs_fscache_get_super_cookie(s, data);
}
mntroot = nfs4_get_root(s, mntfh);
@ -2411,6 +2450,7 @@ static int nfs4_get_sb(struct file_system_type *fs_type,
kfree(data->client_address);
kfree(data->nfs_server.export_path);
kfree(data->nfs_server.hostname);
kfree(data->fscache_uniq);
security_free_mnt_opts(&data->lsm_opts);
out_free_fh:
kfree(mntfh);
@ -2437,6 +2477,7 @@ static void nfs4_kill_super(struct super_block *sb)
kill_anon_super(sb);
nfs4_renewd_prepare_shutdown(server);
nfs_fscache_release_super_cookie(sb);
nfs_free_server(server);
}

3
fs/splice.c
View File

@ -59,7 +59,8 @@ static int page_cache_pipe_buf_steal(struct pipe_inode_info *pipe,
*/
wait_on_page_writeback(page);
if (PagePrivate(page) && !try_to_release_page(page, GFP_KERNEL))
if (page_has_private(page) &&
!try_to_release_page(page, GFP_KERNEL))
goto out_unlock;
/*

1
fs/super.c
View File

@ -287,6 +287,7 @@ int fsync_super(struct super_block *sb)
__fsync_super(sb);
return sync_blockdev(sb->s_bdev);
}
EXPORT_SYMBOL_GPL(fsync_super);
/**
* generic_shutdown_super - common helper for ->kill_sb()

505
include/linux/fscache-cache.h Normal file
View File

@ -0,0 +1,505 @@
/* General filesystem caching backing cache interface
*
* Copyright (C) 2004-2007 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*
* NOTE!!! See:
*
* Documentation/filesystems/caching/backend-api.txt
*
* for a description of the cache backend interface declared here.
*/
#ifndef _LINUX_FSCACHE_CACHE_H
#define _LINUX_FSCACHE_CACHE_H
#include <linux/fscache.h>
#include <linux/sched.h>
#include <linux/slow-work.h>
#define NR_MAXCACHES BITS_PER_LONG
struct fscache_cache;
struct fscache_cache_ops;
struct fscache_object;
struct fscache_operation;
/*
* cache tag definition
*/
struct fscache_cache_tag {
struct list_head link;
struct fscache_cache *cache; /* cache referred to by this tag */
unsigned long flags;
#define FSCACHE_TAG_RESERVED 0 /* T if tag is reserved for a cache */
atomic_t usage;
char name[0]; /* tag name */
};
/*
* cache definition
*/
struct fscache_cache {
const struct fscache_cache_ops *ops;
struct fscache_cache_tag *tag; /* tag representing this cache */
struct kobject *kobj; /* system representation of this cache */
struct list_head link; /* link in list of caches */
size_t max_index_size; /* maximum size of index data */
char identifier[36]; /* cache label */
/* node management */
struct work_struct op_gc; /* operation garbage collector */
struct list_head object_list; /* list of data/index objects */
struct list_head op_gc_list; /* list of ops to be deleted */
spinlock_t object_list_lock;
spinlock_t op_gc_list_lock;
atomic_t object_count; /* no. of live objects in this cache */
struct fscache_object *fsdef; /* object for the fsdef index */
unsigned long flags;
#define FSCACHE_IOERROR 0 /* cache stopped on I/O error */
#define FSCACHE_CACHE_WITHDRAWN 1 /* cache has been withdrawn */
};
extern wait_queue_head_t fscache_cache_cleared_wq;
/*
* operation to be applied to a cache object
* - retrieval initiation operations are done in the context of the process
* that issued them, and not in an async thread pool
*/
typedef void (*fscache_operation_release_t)(struct fscache_operation *op);
typedef void (*fscache_operation_processor_t)(struct fscache_operation *op);
struct fscache_operation {
union {
struct work_struct fast_work; /* record for fast ops */
struct slow_work slow_work; /* record for (very) slow ops */
};
struct list_head pend_link; /* link in object->pending_ops */
struct fscache_object *object; /* object to be operated upon */
unsigned long flags;
#define FSCACHE_OP_TYPE 0x000f /* operation type */
#define FSCACHE_OP_FAST 0x0001 /* - fast op, processor may not sleep for disk */
#define FSCACHE_OP_SLOW 0x0002 /* - (very) slow op, processor may sleep for disk */
#define FSCACHE_OP_MYTHREAD 0x0003 /* - processing is done be issuing thread, not pool */
#define FSCACHE_OP_WAITING 4 /* cleared when op is woken */
#define FSCACHE_OP_EXCLUSIVE 5 /* exclusive op, other ops must wait */
#define FSCACHE_OP_DEAD 6 /* op is now dead */
atomic_t usage;
unsigned debug_id; /* debugging ID */
/* operation processor callback
* - can be NULL if FSCACHE_OP_WAITING is going to be used to perform
* the op in a non-pool thread */
fscache_operation_processor_t processor;
/* operation releaser */
fscache_operation_release_t release;
};
extern atomic_t fscache_op_debug_id;
extern const struct slow_work_ops fscache_op_slow_work_ops;
extern void fscache_enqueue_operation(struct fscache_operation *);
extern void fscache_put_operation(struct fscache_operation *);
/**
* fscache_operation_init - Do basic initialisation of an operation
* @op: The operation to initialise
* @release: The release function to assign
*
* Do basic initialisation of an operation. The caller must still set flags,
* object, either fast_work or slow_work if necessary, and processor if needed.
*/
static inline void fscache_operation_init(struct fscache_operation *op,
fscache_operation_release_t release)
{
atomic_set(&op->usage, 1);
op->debug_id = atomic_inc_return(&fscache_op_debug_id);
op->release = release;
INIT_LIST_HEAD(&op->pend_link);
}
/**
* fscache_operation_init_slow - Do additional initialisation of a slow op
* @op: The operation to initialise
* @processor: The processor function to assign
*
* Do additional initialisation of an operation as required for slow work.
*/
static inline
void fscache_operation_init_slow(struct fscache_operation *op,
fscache_operation_processor_t processor)
{
op->processor = processor;
slow_work_init(&op->slow_work, &fscache_op_slow_work_ops);
}
/*
* data read operation
*/
struct fscache_retrieval {
struct fscache_operation op;
struct address_space *mapping; /* netfs pages */
fscache_rw_complete_t end_io_func; /* function to call on I/O completion */
void *context; /* netfs read context (pinned) */
struct list_head to_do; /* list of things to be done by the backend */
unsigned long start_time; /* time at which retrieval started */
};
typedef int (*fscache_page_retrieval_func_t)(struct fscache_retrieval *op,
struct page *page,
gfp_t gfp);
typedef int (*fscache_pages_retrieval_func_t)(struct fscache_retrieval *op,
struct list_head *pages,
unsigned *nr_pages,
gfp_t gfp);
/**
* fscache_get_retrieval - Get an extra reference on a retrieval operation
* @op: The retrieval operation to get a reference on
*
* Get an extra reference on a retrieval operation.
*/
static inline
struct fscache_retrieval *fscache_get_retrieval(struct fscache_retrieval *op)
{
atomic_inc(&op->op.usage);
return op;
}
/**
* fscache_enqueue_retrieval - Enqueue a retrieval operation for processing
* @op: The retrieval operation affected
*
* Enqueue a retrieval operation for processing by the FS-Cache thread pool.
*/
static inline void fscache_enqueue_retrieval(struct fscache_retrieval *op)
{
fscache_enqueue_operation(&op->op);
}
/**
* fscache_put_retrieval - Drop a reference to a retrieval operation
* @op: The retrieval operation affected
*
* Drop a reference to a retrieval operation.
*/
static inline void fscache_put_retrieval(struct fscache_retrieval *op)
{
fscache_put_operation(&op->op);
}
/*
* cached page storage work item
* - used to do three things:
* - batch writes to the cache
* - do cache writes asynchronously
* - defer writes until cache object lookup completion
*/
struct fscache_storage {
struct fscache_operation op;
pgoff_t store_limit; /* don't write more than this */
};
/*
* cache operations
*/
struct fscache_cache_ops {
/* name of cache provider */
const char *name;
/* allocate an object record for a cookie */
struct fscache_object *(*alloc_object)(struct fscache_cache *cache,
struct fscache_cookie *cookie);
/* look up the object for a cookie */
void (*lookup_object)(struct fscache_object *object);
/* finished looking up */
void (*lookup_complete)(struct fscache_object *object);
/* increment the usage count on this object (may fail if unmounting) */
struct fscache_object *(*grab_object)(struct fscache_object *object);
/* pin an object in the cache */
int (*pin_object)(struct fscache_object *object);
/* unpin an object in the cache */
void (*unpin_object)(struct fscache_object *object);
/* store the updated auxilliary data on an object */
void (*update_object)(struct fscache_object *object);
/* discard the resources pinned by an object and effect retirement if
* necessary */
void (*drop_object)(struct fscache_object *object);
/* dispose of a reference to an object */
void (*put_object)(struct fscache_object *object);
/* sync a cache */
void (*sync_cache)(struct fscache_cache *cache);
/* notification that the attributes of a non-index object (such as
* i_size) have changed */
int (*attr_changed)(struct fscache_object *object);
/* reserve space for an object's data and associated metadata */
int (*reserve_space)(struct fscache_object *object, loff_t i_size);
/* request a backing block for a page be read or allocated in the
* cache */
fscache_page_retrieval_func_t read_or_alloc_page;
/* request backing blocks for a list of pages be read or allocated in
* the cache */
fscache_pages_retrieval_func_t read_or_alloc_pages;
/* request a backing block for a page be allocated in the cache so that
* it can be written directly */
fscache_page_retrieval_func_t allocate_page;
/* request backing blocks for pages be allocated in the cache so that
* they can be written directly */
fscache_pages_retrieval_func_t allocate_pages;
/* write a page to its backing block in the cache */
int (*write_page)(struct fscache_storage *op, struct page *page);
/* detach backing block from a page (optional)
* - must release the cookie lock before returning
* - may sleep
*/
void (*uncache_page)(struct fscache_object *object,
struct page *page);
/* dissociate a cache from all the pages it was backing */
void (*dissociate_pages)(struct fscache_cache *cache);
};
/*
* data file or index object cookie
* - a file will only appear in one cache
* - a request to cache a file may or may not be honoured, subject to
* constraints such as disk space
* - indices are created on disk just-in-time
*/
struct fscache_cookie {
atomic_t usage; /* number of users of this cookie */
atomic_t n_children; /* number of children of this cookie */
spinlock_t lock;
struct hlist_head backing_objects; /* object(s) backing this file/index */
const struct fscache_cookie_def *def; /* definition */
struct fscache_cookie *parent; /* parent of this entry */
void *netfs_data; /* back pointer to netfs */
struct radix_tree_root stores; /* pages to be stored on this cookie */
#define FSCACHE_COOKIE_PENDING_TAG 0 /* pages tag: pending write to cache */
unsigned long flags;
#define FSCACHE_COOKIE_LOOKING_UP 0 /* T if non-index cookie being looked up still */
#define FSCACHE_COOKIE_CREATING 1 /* T if non-index object being created still */
#define FSCACHE_COOKIE_NO_DATA_YET 2 /* T if new object with no cached data yet */
#define FSCACHE_COOKIE_PENDING_FILL 3 /* T if pending initial fill on object */
#define FSCACHE_COOKIE_FILLING 4 /* T if filling object incrementally */
#define FSCACHE_COOKIE_UNAVAILABLE 5 /* T if cookie is unavailable (error, etc) */
};
extern struct fscache_cookie fscache_fsdef_index;
/*
* on-disk cache file or index handle
*/
struct fscache_object {
enum fscache_object_state {
FSCACHE_OBJECT_INIT, /* object in initial unbound state */
FSCACHE_OBJECT_LOOKING_UP, /* looking up object */
FSCACHE_OBJECT_CREATING, /* creating object */
/* active states */
FSCACHE_OBJECT_AVAILABLE, /* cleaning up object after creation */
FSCACHE_OBJECT_ACTIVE, /* object is usable */
FSCACHE_OBJECT_UPDATING, /* object is updating */
/* terminal states */
FSCACHE_OBJECT_DYING, /* object waiting for accessors to finish */
FSCACHE_OBJECT_LC_DYING, /* object cleaning up after lookup/create */
FSCACHE_OBJECT_ABORT_INIT, /* abort the init state */
FSCACHE_OBJECT_RELEASING, /* releasing object */
FSCACHE_OBJECT_RECYCLING, /* retiring object */
FSCACHE_OBJECT_WITHDRAWING, /* withdrawing object */
FSCACHE_OBJECT_DEAD, /* object is now dead */
} state;
int debug_id; /* debugging ID */
int n_children; /* number of child objects */
int n_ops; /* number of ops outstanding on object */
int n_obj_ops; /* number of object ops outstanding on object */
int n_in_progress; /* number of ops in progress */
int n_exclusive; /* number of exclusive ops queued */
spinlock_t lock; /* state and operations lock */
unsigned long lookup_jif; /* time at which lookup started */
unsigned long event_mask; /* events this object is interested in */
unsigned long events; /* events to be processed by this object
* (order is important - using fls) */
#define FSCACHE_OBJECT_EV_REQUEUE 0 /* T if object should be requeued */
#define FSCACHE_OBJECT_EV_UPDATE 1 /* T if object should be updated */
#define FSCACHE_OBJECT_EV_CLEARED 2 /* T if accessors all gone */
#define FSCACHE_OBJECT_EV_ERROR 3 /* T if fatal error occurred during processing */
#define FSCACHE_OBJECT_EV_RELEASE 4 /* T if netfs requested object release */
#define FSCACHE_OBJECT_EV_RETIRE 5 /* T if netfs requested object retirement */
#define FSCACHE_OBJECT_EV_WITHDRAW 6 /* T if cache requested object withdrawal */
unsigned long flags;
#define FSCACHE_OBJECT_LOCK 0 /* T if object is busy being processed */
#define FSCACHE_OBJECT_PENDING_WRITE 1 /* T if object has pending write */
#define FSCACHE_OBJECT_WAITING 2 /* T if object is waiting on its parent */
struct list_head cache_link; /* link in cache->object_list */
struct hlist_node cookie_link; /* link in cookie->backing_objects */
struct fscache_cache *cache; /* cache that supplied this object */
struct fscache_cookie *cookie; /* netfs's file/index object */
struct fscache_object *parent; /* parent object */
struct slow_work work; /* attention scheduling record */
struct list_head dependents; /* FIFO of dependent objects */
struct list_head dep_link; /* link in parent's dependents list */
struct list_head pending_ops; /* unstarted operations on this object */
pgoff_t store_limit; /* current storage limit */
};
extern const char *fscache_object_states[];
#define fscache_object_is_active(obj) \
(!test_bit(FSCACHE_IOERROR, &(obj)->cache->flags) && \
(obj)->state >= FSCACHE_OBJECT_AVAILABLE && \
(obj)->state < FSCACHE_OBJECT_DYING)
extern const struct slow_work_ops fscache_object_slow_work_ops;
/**
* fscache_object_init - Initialise a cache object description
* @object: Object description
*
* Initialise a cache object description to its basic values.
*
* See Documentation/filesystems/caching/backend-api.txt for a complete
* description.
*/
static inline
void fscache_object_init(struct fscache_object *object,
struct fscache_cookie *cookie,
struct fscache_cache *cache)
{
atomic_inc(&cache->object_count);
object->state = FSCACHE_OBJECT_INIT;
spin_lock_init(&object->lock);
INIT_LIST_HEAD(&object->cache_link);
INIT_HLIST_NODE(&object->cookie_link);
vslow_work_init(&object->work, &fscache_object_slow_work_ops);
INIT_LIST_HEAD(&object->dependents);
INIT_LIST_HEAD(&object->dep_link);
INIT_LIST_HEAD(&object->pending_ops);
object->n_children = 0;
object->n_ops = object->n_in_progress = object->n_exclusive = 0;
object->events = object->event_mask = 0;
object->flags = 0;
object->store_limit = 0;
object->cache = cache;
object->cookie = cookie;
object->parent = NULL;
}
extern void fscache_object_lookup_negative(struct fscache_object *object);
extern void fscache_obtained_object(struct fscache_object *object);
/**
* fscache_object_destroyed - Note destruction of an object in a cache
* @cache: The cache from which the object came
*
* Note the destruction and deallocation of an object record in a cache.
*/
static inline void fscache_object_destroyed(struct fscache_cache *cache)
{
if (atomic_dec_and_test(&cache->object_count))
wake_up_all(&fscache_cache_cleared_wq);
}
/**
* fscache_object_lookup_error - Note an object encountered an error
* @object: The object on which the error was encountered
*
* Note that an object encountered a fatal error (usually an I/O error) and
* that it should be withdrawn as soon as possible.
*/
static inline void fscache_object_lookup_error(struct fscache_object *object)
{
set_bit(FSCACHE_OBJECT_EV_ERROR, &object->events);
}
/**
* fscache_set_store_limit - Set the maximum size to be stored in an object
* @object: The object to set the maximum on
* @i_size: The limit to set in bytes
*
* Set the maximum size an object is permitted to reach, implying the highest
* byte that may be written. Intended to be called by the attr_changed() op.
*
* See Documentation/filesystems/caching/backend-api.txt for a complete
* description.
*/
static inline
void fscache_set_store_limit(struct fscache_object *object, loff_t i_size)
{
object->store_limit = i_size >> PAGE_SHIFT;
if (i_size & ~PAGE_MASK)
object->store_limit++;
}
/**
* fscache_end_io - End a retrieval operation on a page
* @op: The FS-Cache operation covering the retrieval
* @page: The page that was to be fetched
* @error: The error code (0 if successful)
*
* Note the end of an operation to retrieve a page, as covered by a particular
* operation record.
*/
static inline void fscache_end_io(struct fscache_retrieval *op,
struct page *page, int error)
{
op->end_io_func(page, op->context, error);
}
/*
* out-of-line cache backend functions
*/
extern void fscache_init_cache(struct fscache_cache *cache,
const struct fscache_cache_ops *ops,
const char *idfmt,
...) __attribute__ ((format (printf, 3, 4)));
extern int fscache_add_cache(struct fscache_cache *cache,
struct fscache_object *fsdef,
const char *tagname);
extern void fscache_withdraw_cache(struct fscache_cache *cache);
extern void fscache_io_error(struct fscache_cache *cache);
extern void fscache_mark_pages_cached(struct fscache_retrieval *op,
struct pagevec *pagevec);
extern enum fscache_checkaux fscache_check_aux(struct fscache_object *object,
const void *data,
uint16_t datalen);
#endif /* _LINUX_FSCACHE_CACHE_H */

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/* General filesystem caching interface
*
* Copyright (C) 2004-2007 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*
* NOTE!!! See:
*
* Documentation/filesystems/caching/netfs-api.txt
*
* for a description of the network filesystem interface declared here.
*/
#ifndef _LINUX_FSCACHE_H
#define _LINUX_FSCACHE_H
#include <linux/fs.h>
#include <linux/list.h>
#include <linux/pagemap.h>
#include <linux/pagevec.h>
#if defined(CONFIG_FSCACHE) || defined(CONFIG_FSCACHE_MODULE)
#define fscache_available() (1)
#define fscache_cookie_valid(cookie) (cookie)
#else
#define fscache_available() (0)
#define fscache_cookie_valid(cookie) (0)
#endif
/*
* overload PG_private_2 to give us PG_fscache - this is used to indicate that
* a page is currently backed by a local disk cache
*/
#define PageFsCache(page) PagePrivate2((page))
#define SetPageFsCache(page) SetPagePrivate2((page))
#define ClearPageFsCache(page) ClearPagePrivate2((page))
#define TestSetPageFsCache(page) TestSetPagePrivate2((page))
#define TestClearPageFsCache(page) TestClearPagePrivate2((page))
/* pattern used to fill dead space in an index entry */
#define FSCACHE_INDEX_DEADFILL_PATTERN 0x79
struct pagevec;
struct fscache_cache_tag;
struct fscache_cookie;
struct fscache_netfs;
typedef void (*fscache_rw_complete_t)(struct page *page,
void *context,
int error);
/* result of index entry consultation */
enum fscache_checkaux {
FSCACHE_CHECKAUX_OKAY, /* entry okay as is */
FSCACHE_CHECKAUX_NEEDS_UPDATE, /* entry requires update */
FSCACHE_CHECKAUX_OBSOLETE, /* entry requires deletion */
};
/*
* fscache cookie definition
*/
struct fscache_cookie_def {
/* name of cookie type */
char name[16];
/* cookie type */
uint8_t type;
#define FSCACHE_COOKIE_TYPE_INDEX 0
#define FSCACHE_COOKIE_TYPE_DATAFILE 1
/* select the cache into which to insert an entry in this index
* - optional
* - should return a cache identifier or NULL to cause the cache to be
* inherited from the parent if possible or the first cache picked
* for a non-index file if not
*/
struct fscache_cache_tag *(*select_cache)(
const void *parent_netfs_data,
const void *cookie_netfs_data);
/* get an index key
* - should store the key data in the buffer
* - should return the amount of amount stored
* - not permitted to return an error
* - the netfs data from the cookie being used as the source is
* presented
*/
uint16_t (*get_key)(const void *cookie_netfs_data,
void *buffer,
uint16_t bufmax);
/* get certain file attributes from the netfs data
* - this function can be absent for an index
* - not permitted to return an error
* - the netfs data from the cookie being used as the source is
* presented
*/
void (*get_attr)(const void *cookie_netfs_data, uint64_t *size);
/* get the auxilliary data from netfs data
* - this function can be absent if the index carries no state data
* - should store the auxilliary data in the buffer
* - should return the amount of amount stored
* - not permitted to return an error
* - the netfs data from the cookie being used as the source is
* presented
*/
uint16_t (*get_aux)(const void *cookie_netfs_data,
void *buffer,
uint16_t bufmax);
/* consult the netfs about the state of an object
* - this function can be absent if the index carries no state data
* - the netfs data from the cookie being used as the target is
* presented, as is the auxilliary data
*/
enum fscache_checkaux (*check_aux)(void *cookie_netfs_data,
const void *data,
uint16_t datalen);
/* get an extra reference on a read context
* - this function can be absent if the completion function doesn't
* require a context
*/
void (*get_context)(void *cookie_netfs_data, void *context);
/* release an extra reference on a read context
* - this function can be absent if the completion function doesn't
* require a context
*/
void (*put_context)(void *cookie_netfs_data, void *context);
/* indicate pages that now have cache metadata retained
* - this function should mark the specified pages as now being cached
* - the pages will have been marked with PG_fscache before this is
* called, so this is optional
*/
void (*mark_pages_cached)(void *cookie_netfs_data,
struct address_space *mapping,
struct pagevec *cached_pvec);
/* indicate the cookie is no longer cached
* - this function is called when the backing store currently caching
* a cookie is removed
* - the netfs should use this to clean up any markers indicating
* cached pages
* - this is mandatory for any object that may have data
*/
void (*now_uncached)(void *cookie_netfs_data);
};
/*
* fscache cached network filesystem type
* - name, version and ops must be filled in before registration
* - all other fields will be set during registration
*/
struct fscache_netfs {
uint32_t version; /* indexing version */
const char *name; /* filesystem name */
struct fscache_cookie *primary_index;
struct list_head link; /* internal link */
};
/*
* slow-path functions for when there is actually caching available, and the
* netfs does actually have a valid token
* - these are not to be called directly
* - these are undefined symbols when FS-Cache is not configured and the
* optimiser takes care of not using them
*/
extern int __fscache_register_netfs(struct fscache_netfs *);
extern void __fscache_unregister_netfs(struct fscache_netfs *);
extern struct fscache_cache_tag *__fscache_lookup_cache_tag(const char *);
extern void __fscache_release_cache_tag(struct fscache_cache_tag *);
extern struct fscache_cookie *__fscache_acquire_cookie(
struct fscache_cookie *,
const struct fscache_cookie_def *,
void *);
extern void __fscache_relinquish_cookie(struct fscache_cookie *, int);
extern void __fscache_update_cookie(struct fscache_cookie *);
extern int __fscache_attr_changed(struct fscache_cookie *);
extern int __fscache_read_or_alloc_page(struct fscache_cookie *,
struct page *,
fscache_rw_complete_t,
void *,
gfp_t);
extern int __fscache_read_or_alloc_pages(struct fscache_cookie *,
struct address_space *,
struct list_head *,
unsigned *,
fscache_rw_complete_t,
void *,
gfp_t);
extern int __fscache_alloc_page(struct fscache_cookie *, struct page *, gfp_t);
extern int __fscache_write_page(struct fscache_cookie *, struct page *, gfp_t);
extern void __fscache_uncache_page(struct fscache_cookie *, struct page *);
extern bool __fscache_check_page_write(struct fscache_cookie *, struct page *);
extern void __fscache_wait_on_page_write(struct fscache_cookie *, struct page *);
/**
* fscache_register_netfs - Register a filesystem as desiring caching services
* @netfs: The description of the filesystem
*
* Register a filesystem as desiring caching services if they're available.
*
* See Documentation/filesystems/caching/netfs-api.txt for a complete
* description.
*/
static inline
int fscache_register_netfs(struct fscache_netfs *netfs)
{
if (fscache_available())
return __fscache_register_netfs(netfs);
else
return 0;
}
/**
* fscache_unregister_netfs - Indicate that a filesystem no longer desires
* caching services
* @netfs: The description of the filesystem
*
* Indicate that a filesystem no longer desires caching services for the
* moment.
*
* See Documentation/filesystems/caching/netfs-api.txt for a complete
* description.
*/
static inline
void fscache_unregister_netfs(struct fscache_netfs *netfs)
{
if (fscache_available())
__fscache_unregister_netfs(netfs);
}
/**
* fscache_lookup_cache_tag - Look up a cache tag
* @name: The name of the tag to search for
*
* Acquire a specific cache referral tag that can be used to select a specific
* cache in which to cache an index.
*
* See Documentation/filesystems/caching/netfs-api.txt for a complete
* description.
*/
static inline
struct fscache_cache_tag *fscache_lookup_cache_tag(const char *name)
{
if (fscache_available())
return __fscache_lookup_cache_tag(name);
else
return NULL;
}
/**
* fscache_release_cache_tag - Release a cache tag
* @tag: The tag to release
*
* Release a reference to a cache referral tag previously looked up.
*
* See Documentation/filesystems/caching/netfs-api.txt for a complete
* description.
*/
static inline
void fscache_release_cache_tag(struct fscache_cache_tag *tag)
{
if (fscache_available())
__fscache_release_cache_tag(tag);
}
/**
* fscache_acquire_cookie - Acquire a cookie to represent a cache object
* @parent: The cookie that's to be the parent of this one
* @def: A description of the cache object, including callback operations
* @netfs_data: An arbitrary piece of data to be kept in the cookie to
* represent the cache object to the netfs
*
* This function is used to inform FS-Cache about part of an index hierarchy
* that can be used to locate files. This is done by requesting a cookie for
* each index in the path to the file.
*
* See Documentation/filesystems/caching/netfs-api.txt for a complete
* description.
*/
static inline
struct fscache_cookie *fscache_acquire_cookie(
struct fscache_cookie *parent,
const struct fscache_cookie_def *def,
void *netfs_data)
{
if (fscache_cookie_valid(parent))
return __fscache_acquire_cookie(parent, def, netfs_data);
else
return NULL;
}
/**
* fscache_relinquish_cookie - Return the cookie to the cache, maybe discarding
* it
* @cookie: The cookie being returned
* @retire: True if the cache object the cookie represents is to be discarded
*
* This function returns a cookie to the cache, forcibly discarding the
* associated cache object if retire is set to true.
*
* See Documentation/filesystems/caching/netfs-api.txt for a complete
* description.
*/
static inline
void fscache_relinquish_cookie(struct fscache_cookie *cookie, int retire)
{
if (fscache_cookie_valid(cookie))
__fscache_relinquish_cookie(cookie, retire);
}
/**
* fscache_update_cookie - Request that a cache object be updated
* @cookie: The cookie representing the cache object
*
* Request an update of the index data for the cache object associated with the
* cookie.
*
* See Documentation/filesystems/caching/netfs-api.txt for a complete
* description.
*/
static inline
void fscache_update_cookie(struct fscache_cookie *cookie)
{
if (fscache_cookie_valid(cookie))
__fscache_update_cookie(cookie);
}
/**
* fscache_pin_cookie - Pin a data-storage cache object in its cache
* @cookie: The cookie representing the cache object
*
* Permit data-storage cache objects to be pinned in the cache.
*
* See Documentation/filesystems/caching/netfs-api.txt for a complete
* description.
*/
static inline
int fscache_pin_cookie(struct fscache_cookie *cookie)
{
return -ENOBUFS;
}
/**
* fscache_pin_cookie - Unpin a data-storage cache object in its cache
* @cookie: The cookie representing the cache object
*
* Permit data-storage cache objects to be unpinned from the cache.
*
* See Documentation/filesystems/caching/netfs-api.txt for a complete
* description.
*/
static inline
void fscache_unpin_cookie(struct fscache_cookie *cookie)
{
}
/**
* fscache_attr_changed - Notify cache that an object's attributes changed
* @cookie: The cookie representing the cache object
*
* Send a notification to the cache indicating that an object's attributes have
* changed. This includes the data size. These attributes will be obtained
* through the get_attr() cookie definition op.
*
* See Documentation/filesystems/caching/netfs-api.txt for a complete
* description.
*/
static inline
int fscache_attr_changed(struct fscache_cookie *cookie)
{
if (fscache_cookie_valid(cookie))
return __fscache_attr_changed(cookie);
else
return -ENOBUFS;
}
/**
* fscache_reserve_space - Reserve data space for a cached object
* @cookie: The cookie representing the cache object
* @i_size: The amount of space to be reserved
*
* Reserve an amount of space in the cache for the cache object attached to a
* cookie so that a write to that object within the space can always be
* honoured.
*
* See Documentation/filesystems/caching/netfs-api.txt for a complete
* description.
*/
static inline
int fscache_reserve_space(struct fscache_cookie *cookie, loff_t size)
{
return -ENOBUFS;
}
/**
* fscache_read_or_alloc_page - Read a page from the cache or allocate a block
* in which to store it
* @cookie: The cookie representing the cache object
* @page: The netfs page to fill if possible
* @end_io_func: The callback to invoke when and if the page is filled
* @context: An arbitrary piece of data to pass on to end_io_func()
* @gfp: The conditions under which memory allocation should be made
*
* Read a page from the cache, or if that's not possible make a potential
* one-block reservation in the cache into which the page may be stored once
* fetched from the server.
*
* If the page is not backed by the cache object, or if it there's some reason
* it can't be, -ENOBUFS will be returned and nothing more will be done for
* that page.
*
* Else, if that page is backed by the cache, a read will be initiated directly
* to the netfs's page and 0 will be returned by this function. The
* end_io_func() callback will be invoked when the operation terminates on a
* completion or failure. Note that the callback may be invoked before the
* return.
*
* Else, if the page is unbacked, -ENODATA is returned and a block may have
* been allocated in the cache.
*
* See Documentation/filesystems/caching/netfs-api.txt for a complete
* description.
*/
static inline
int fscache_read_or_alloc_page(struct fscache_cookie *cookie,
struct page *page,
fscache_rw_complete_t end_io_func,
void *context,
gfp_t gfp)
{
if (fscache_cookie_valid(cookie))
return __fscache_read_or_alloc_page(cookie, page, end_io_func,
context, gfp);
else
return -ENOBUFS;
}
/**
* fscache_read_or_alloc_pages - Read pages from the cache and/or allocate
* blocks in which to store them
* @cookie: The cookie representing the cache object
* @mapping: The netfs inode mapping to which the pages will be attached
* @pages: A list of potential netfs pages to be filled
* @end_io_func: The callback to invoke when and if each page is filled
* @context: An arbitrary piece of data to pass on to end_io_func()
* @gfp: The conditions under which memory allocation should be made
*
* Read a set of pages from the cache, or if that's not possible, attempt to
* make a potential one-block reservation for each page in the cache into which
* that page may be stored once fetched from the server.
*
* If some pages are not backed by the cache object, or if it there's some
* reason they can't be, -ENOBUFS will be returned and nothing more will be
* done for that pages.
*
* Else, if some of the pages are backed by the cache, a read will be initiated
* directly to the netfs's page and 0 will be returned by this function. The
* end_io_func() callback will be invoked when the operation terminates on a
* completion or failure. Note that the callback may be invoked before the
* return.
*
* Else, if a page is unbacked, -ENODATA is returned and a block may have
* been allocated in the cache.
*
* Because the function may want to return all of -ENOBUFS, -ENODATA and 0 in
* regard to different pages, the return values are prioritised in that order.
* Any pages submitted for reading are removed from the pages list.
*
* See Documentation/filesystems/caching/netfs-api.txt for a complete
* description.
*/
static inline
int fscache_read_or_alloc_pages(struct fscache_cookie *cookie,
struct address_space *mapping,
struct list_head *pages,
unsigned *nr_pages,
fscache_rw_complete_t end_io_func,
void *context,
gfp_t gfp)
{
if (fscache_cookie_valid(cookie))
return __fscache_read_or_alloc_pages(cookie, mapping, pages,
nr_pages, end_io_func,
context, gfp);
else
return -ENOBUFS;
}
/**
* fscache_alloc_page - Allocate a block in which to store a page
* @cookie: The cookie representing the cache object
* @page: The netfs page to allocate a page for
* @gfp: The conditions under which memory allocation should be made
*
* Request Allocation a block in the cache in which to store a netfs page
* without retrieving any contents from the cache.
*
* If the page is not backed by a file then -ENOBUFS will be returned and
* nothing more will be done, and no reservation will be made.
*
* Else, a block will be allocated if one wasn't already, and 0 will be
* returned
*
* See Documentation/filesystems/caching/netfs-api.txt for a complete
* description.
*/
static inline
int fscache_alloc_page(struct fscache_cookie *cookie,
struct page *page,
gfp_t gfp)
{
if (fscache_cookie_valid(cookie))
return __fscache_alloc_page(cookie, page, gfp);
else
return -ENOBUFS;
}
/**
* fscache_write_page - Request storage of a page in the cache
* @cookie: The cookie representing the cache object
* @page: The netfs page to store
* @gfp: The conditions under which memory allocation should be made
*
* Request the contents of the netfs page be written into the cache. This
* request may be ignored if no cache block is currently allocated, in which
* case it will return -ENOBUFS.
*
* If a cache block was already allocated, a write will be initiated and 0 will
* be returned. The PG_fscache_write page bit is set immediately and will then
* be cleared at the completion of the write to indicate the success or failure
* of the operation. Note that the completion may happen before the return.
*
* See Documentation/filesystems/caching/netfs-api.txt for a complete
* description.
*/
static inline
int fscache_write_page(struct fscache_cookie *cookie,
struct page *page,
gfp_t gfp)
{
if (fscache_cookie_valid(cookie))
return __fscache_write_page(cookie, page, gfp);
else
return -ENOBUFS;
}
/**
* fscache_uncache_page - Indicate that caching is no longer required on a page
* @cookie: The cookie representing the cache object
* @page: The netfs page that was being cached.
*
* Tell the cache that we no longer want a page to be cached and that it should
* remove any knowledge of the netfs page it may have.
*
* Note that this cannot cancel any outstanding I/O operations between this
* page and the cache.
*
* See Documentation/filesystems/caching/netfs-api.txt for a complete
* description.
*/
static inline
void fscache_uncache_page(struct fscache_cookie *cookie,
struct page *page)
{
if (fscache_cookie_valid(cookie))
__fscache_uncache_page(cookie, page);
}
/**
* fscache_check_page_write - Ask if a page is being writing to the cache
* @cookie: The cookie representing the cache object
* @page: The netfs page that is being cached.
*
* Ask the cache if a page is being written to the cache.
*
* See Documentation/filesystems/caching/netfs-api.txt for a complete
* description.
*/
static inline
bool fscache_check_page_write(struct fscache_cookie *cookie,
struct page *page)
{
if (fscache_cookie_valid(cookie))
return __fscache_check_page_write(cookie, page);
return false;
}
/**
* fscache_wait_on_page_write - Wait for a page to complete writing to the cache
* @cookie: The cookie representing the cache object
* @page: The netfs page that is being cached.
*
* Ask the cache to wake us up when a page is no longer being written to the
* cache.
*
* See Documentation/filesystems/caching/netfs-api.txt for a complete
* description.
*/
static inline
void fscache_wait_on_page_write(struct fscache_cookie *cookie,
struct page *page)
{
if (fscache_cookie_valid(cookie))
__fscache_wait_on_page_write(cookie, page);
}
#endif /* _LINUX_FSCACHE_H */

13
include/linux/nfs_fs.h
View File

@ -185,6 +185,9 @@ struct nfs_inode {
fmode_t delegation_state;
struct rw_semaphore rwsem;
#endif /* CONFIG_NFS_V4*/
#ifdef CONFIG_NFS_FSCACHE
struct fscache_cookie *fscache;
#endif
struct inode vfs_inode;
};
@ -207,6 +210,8 @@ struct nfs_inode {
#define NFS_INO_ACL_LRU_SET (2) /* Inode is on the LRU list */
#define NFS_INO_MOUNTPOINT (3) /* inode is remote mountpoint */
#define NFS_INO_FLUSHING (4) /* inode is flushing out data */
#define NFS_INO_FSCACHE (5) /* inode can be cached by FS-Cache */
#define NFS_INO_FSCACHE_LOCK (6) /* FS-Cache cookie management lock */
static inline struct nfs_inode *NFS_I(const struct inode *inode)
{
@ -260,6 +265,11 @@ static inline int NFS_STALE(const struct inode *inode)
return test_bit(NFS_INO_STALE, &NFS_I(inode)->flags);
}
static inline int NFS_FSCACHE(const struct inode *inode)
{
return test_bit(NFS_INO_FSCACHE, &NFS_I(inode)->flags);
}
static inline __u64 NFS_FILEID(const struct inode *inode)
{
return NFS_I(inode)->fileid;
@ -506,6 +516,8 @@ extern int nfs_readpages(struct file *, struct address_space *,
struct list_head *, unsigned);
extern int nfs_readpage_result(struct rpc_task *, struct nfs_read_data *);
extern void nfs_readdata_release(void *data);
extern int nfs_readpage_async(struct nfs_open_context *, struct inode *,
struct page *);
/*
* Allocate nfs_read_data structures
@ -583,6 +595,7 @@ extern void * nfs_root_data(void);
#define NFSDBG_CALLBACK 0x0100
#define NFSDBG_CLIENT 0x0200
#define NFSDBG_MOUNT 0x0400
#define NFSDBG_FSCACHE 0x0800
#define NFSDBG_ALL 0xFFFF
#ifdef __KERNEL__

11
include/linux/nfs_fs_sb.h
View File

@ -64,6 +64,10 @@ struct nfs_client {
char cl_ipaddr[48];
unsigned char cl_id_uniquifier;
#endif
#ifdef CONFIG_NFS_FSCACHE
struct fscache_cookie *fscache; /* client index cache cookie */
#endif
};
/*
@ -96,12 +100,19 @@ struct nfs_server {
unsigned int acdirmin;
unsigned int acdirmax;
unsigned int namelen;
unsigned int options; /* extra options enabled by mount */
#define NFS_OPTION_FSCACHE 0x00000001 /* - local caching enabled */
struct nfs_fsid fsid;
__u64 maxfilesize; /* maximum file size */
unsigned long mount_time; /* when this fs was mounted */
dev_t s_dev; /* superblock dev numbers */
#ifdef CONFIG_NFS_FSCACHE
struct nfs_fscache_key *fscache_key; /* unique key for superblock */
struct fscache_cookie *fscache; /* superblock cookie */
#endif
#ifdef CONFIG_NFS_V4
u32 attr_bitmask[2];/* V4 bitmask representing the set
of attributes supported on this

12
include/linux/nfs_iostat.h
View File

@ -116,4 +116,16 @@ enum nfs_stat_eventcounters {
__NFSIOS_COUNTSMAX,
};
/*
* NFS local caching servicing counters
*/
enum nfs_stat_fscachecounters {
NFSIOS_FSCACHE_PAGES_READ_OK,
NFSIOS_FSCACHE_PAGES_READ_FAIL,
NFSIOS_FSCACHE_PAGES_WRITTEN_OK,
NFSIOS_FSCACHE_PAGES_WRITTEN_FAIL,
NFSIOS_FSCACHE_PAGES_UNCACHED,
__NFSIOS_FSCACHEMAX,
};
#endif /* _LINUX_NFS_IOSTAT */

40
include/linux/page-flags.h
View File

@ -82,6 +82,7 @@ enum pageflags {
PG_arch_1,
PG_reserved,
PG_private, /* If pagecache, has fs-private data */
PG_private_2, /* If pagecache, has fs aux data */
PG_writeback, /* Page is under writeback */
#ifdef CONFIG_PAGEFLAGS_EXTENDED
PG_head, /* A head page */
@ -108,6 +109,12 @@ enum pageflags {
/* Filesystems */
PG_checked = PG_owner_priv_1,
/* Two page bits are conscripted by FS-Cache to maintain local caching
* state. These bits are set on pages belonging to the netfs's inodes
* when those inodes are being locally cached.
*/
PG_fscache = PG_private_2, /* page backed by cache */
/* XEN */
PG_pinned = PG_owner_priv_1,
PG_savepinned = PG_dirty,
@ -182,7 +189,7 @@ static inline int TestClearPage##uname(struct page *page) { return 0; }
struct page; /* forward declaration */
TESTPAGEFLAG(Locked, locked)
TESTPAGEFLAG(Locked, locked) TESTSETFLAG(Locked, locked)
PAGEFLAG(Error, error)
PAGEFLAG(Referenced, referenced) TESTCLEARFLAG(Referenced, referenced)
PAGEFLAG(Dirty, dirty) TESTSCFLAG(Dirty, dirty) __CLEARPAGEFLAG(Dirty, dirty)
@ -194,8 +201,6 @@ PAGEFLAG(Checked, checked) /* Used by some filesystems */
PAGEFLAG(Pinned, pinned) TESTSCFLAG(Pinned, pinned) /* Xen */
PAGEFLAG(SavePinned, savepinned); /* Xen */
PAGEFLAG(Reserved, reserved) __CLEARPAGEFLAG(Reserved, reserved)
PAGEFLAG(Private, private) __CLEARPAGEFLAG(Private, private)
__SETPAGEFLAG(Private, private)
PAGEFLAG(SwapBacked, swapbacked) __CLEARPAGEFLAG(SwapBacked, swapbacked)
__PAGEFLAG(SlobPage, slob_page)
@ -204,6 +209,16 @@ __PAGEFLAG(SlobFree, slob_free)
__PAGEFLAG(SlubFrozen, slub_frozen)
__PAGEFLAG(SlubDebug, slub_debug)
/*
* Private page markings that may be used by the filesystem that owns the page
* for its own purposes.
* - PG_private and PG_private_2 cause releasepage() and co to be invoked
*/
PAGEFLAG(Private, private) __SETPAGEFLAG(Private, private)
__CLEARPAGEFLAG(Private, private)
PAGEFLAG(Private2, private_2) TESTSCFLAG(Private2, private_2)
PAGEFLAG(OwnerPriv1, owner_priv_1) TESTCLEARFLAG(OwnerPriv1, owner_priv_1)
/*
* Only test-and-set exist for PG_writeback. The unconditional operators are
* risky: they bypass page accounting.
@ -384,9 +399,10 @@ static inline void __ClearPageTail(struct page *page)
* these flags set. It they are, there is a problem.
*/
#define PAGE_FLAGS_CHECK_AT_FREE \
(1 << PG_lru | 1 << PG_private | 1 << PG_locked | \
1 << PG_buddy | 1 << PG_writeback | 1 << PG_reserved | \
1 << PG_slab | 1 << PG_swapcache | 1 << PG_active | \
(1 << PG_lru | 1 << PG_locked | \
1 << PG_private | 1 << PG_private_2 | \
1 << PG_buddy | 1 << PG_writeback | 1 << PG_reserved | \
1 << PG_slab | 1 << PG_swapcache | 1 << PG_active | \
__PG_UNEVICTABLE | __PG_MLOCKED)
/*
@ -397,4 +413,16 @@ static inline void __ClearPageTail(struct page *page)
#define PAGE_FLAGS_CHECK_AT_PREP ((1 << NR_PAGEFLAGS) - 1)
#endif /* !__GENERATING_BOUNDS_H */
/**
* page_has_private - Determine if page has private stuff
* @page: The page to be checked
*
* Determine if a page has private stuff, indicating that release routines
* should be invoked upon it.
*/
#define page_has_private(page) \
((page)->flags & ((1 << PG_private) | \
(1 << PG_private_2)))
#endif /* PAGE_FLAGS_H */

5
include/linux/pagemap.h
View File

@ -383,6 +383,11 @@ static inline void wait_on_page_writeback(struct page *page)
extern void end_page_writeback(struct page *page);
/*
* Add an arbitrary waiter to a page's wait queue
*/
extern void add_page_wait_queue(struct page *page, wait_queue_t *waiter);
/*
* Fault a userspace page into pagetables. Return non-zero on a fault.
*

95
include/linux/slow-work.h Normal file
View File

@ -0,0 +1,95 @@
/* Worker thread pool for slow items, such as filesystem lookups or mkdirs
*
* Copyright (C) 2008 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public Licence
* as published by the Free Software Foundation; either version
* 2 of the Licence, or (at your option) any later version.
*
* See Documentation/slow-work.txt
*/
#ifndef _LINUX_SLOW_WORK_H
#define _LINUX_SLOW_WORK_H
#ifdef CONFIG_SLOW_WORK
#include <linux/sysctl.h>
struct slow_work;
/*
* The operations used to support slow work items
*/
struct slow_work_ops {
/* get a ref on a work item
* - return 0 if successful, -ve if not
*/
int (*get_ref)(struct slow_work *work);
/* discard a ref to a work item */
void (*put_ref)(struct slow_work *work);
/* execute a work item */
void (*execute)(struct slow_work *work);
};
/*
* A slow work item
* - A reference is held on the parent object by the thread pool when it is
* queued
*/
struct slow_work {
unsigned long flags;
#define SLOW_WORK_PENDING 0 /* item pending (further) execution */
#define SLOW_WORK_EXECUTING 1 /* item currently executing */
#define SLOW_WORK_ENQ_DEFERRED 2 /* item enqueue deferred */
#define SLOW_WORK_VERY_SLOW 3 /* item is very slow */
const struct slow_work_ops *ops; /* operations table for this item */
struct list_head link; /* link in queue */
};
/**
* slow_work_init - Initialise a slow work item
* @work: The work item to initialise
* @ops: The operations to use to handle the slow work item
*
* Initialise a slow work item.
*/
static inline void slow_work_init(struct slow_work *work,
const struct slow_work_ops *ops)
{
work->flags = 0;
work->ops = ops;
INIT_LIST_HEAD(&work->link);
}
/**
* slow_work_init - Initialise a very slow work item
* @work: The work item to initialise
* @ops: The operations to use to handle the slow work item
*
* Initialise a very slow work item. This item will be restricted such that
* only a certain number of the pool threads will be able to execute items of
* this type.
*/
static inline void vslow_work_init(struct slow_work *work,
const struct slow_work_ops *ops)
{
work->flags = 1 << SLOW_WORK_VERY_SLOW;
work->ops = ops;
INIT_LIST_HEAD(&work->link);
}
extern int slow_work_enqueue(struct slow_work *work);
extern int slow_work_register_user(void);
extern void slow_work_unregister_user(void);
#ifdef CONFIG_SYSCTL
extern ctl_table slow_work_sysctls[];
#endif
#endif /* CONFIG_SLOW_WORK */
#endif /* _LINUX_SLOW_WORK_H */

12
init/Kconfig
View File

@ -1014,6 +1014,18 @@ config MARKERS
source "arch/Kconfig"
config SLOW_WORK
default n
bool "Enable slow work thread pool"
help
The slow work thread pool provides a number of dynamically allocated
threads that can be used by the kernel to perform operations that
take a relatively long time.
An example of this would be CacheFiles doing a path lookup followed
by a series of mkdirs and a create call, all of which have to touch
disk.
endmenu # General setup
config HAVE_GENERIC_DMA_COHERENT

1
kernel/Makefile
View File

@ -93,6 +93,7 @@ obj-$(CONFIG_HAVE_GENERIC_DMA_COHERENT) += dma-coherent.o
obj-$(CONFIG_FUNCTION_TRACER) += trace/
obj-$(CONFIG_TRACING) += trace/
obj-$(CONFIG_SMP) += sched_cpupri.o
obj-$(CONFIG_SLOW_WORK) += slow-work.o
ifneq ($(CONFIG_SCHED_OMIT_FRAME_POINTER),y)
# According to Alan Modra <alan@linuxcare.com.au>, the -fno-omit-frame-pointer is

640
kernel/slow-work.c Normal file
View File

@ -0,0 +1,640 @@
/* Worker thread pool for slow items, such as filesystem lookups or mkdirs
*
* Copyright (C) 2008 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public Licence
* as published by the Free Software Foundation; either version
* 2 of the Licence, or (at your option) any later version.
*
* See Documentation/slow-work.txt
*/
#include <linux/module.h>
#include <linux/slow-work.h>
#include <linux/kthread.h>
#include <linux/freezer.h>
#include <linux/wait.h>
#define SLOW_WORK_CULL_TIMEOUT (5 * HZ) /* cull threads 5s after running out of
* things to do */
#define SLOW_WORK_OOM_TIMEOUT (5 * HZ) /* can't start new threads for 5s after
* OOM */
static void slow_work_cull_timeout(unsigned long);
static void slow_work_oom_timeout(unsigned long);
#ifdef CONFIG_SYSCTL
static int slow_work_min_threads_sysctl(struct ctl_table *, int, struct file *,
void __user *, size_t *, loff_t *);
static int slow_work_max_threads_sysctl(struct ctl_table *, int , struct file *,
void __user *, size_t *, loff_t *);
#endif
/*
* The pool of threads has at least min threads in it as long as someone is
* using the facility, and may have as many as max.
*
* A portion of the pool may be processing very slow operations.
*/
static unsigned slow_work_min_threads = 2;
static unsigned slow_work_max_threads = 4;
static unsigned vslow_work_proportion = 50; /* % of threads that may process
* very slow work */
#ifdef CONFIG_SYSCTL
static const int slow_work_min_min_threads = 2;
static int slow_work_max_max_threads = 255;
static const int slow_work_min_vslow = 1;
static const int slow_work_max_vslow = 99;
ctl_table slow_work_sysctls[] = {
{
.ctl_name = CTL_UNNUMBERED,
.procname = "min-threads",
.data = &slow_work_min_threads,
.maxlen = sizeof(unsigned),
.mode = 0644,
.proc_handler = slow_work_min_threads_sysctl,
.extra1 = (void *) &slow_work_min_min_threads,
.extra2 = &slow_work_max_threads,
},
{
.ctl_name = CTL_UNNUMBERED,
.procname = "max-threads",
.data = &slow_work_max_threads,
.maxlen = sizeof(unsigned),
.mode = 0644,
.proc_handler = slow_work_max_threads_sysctl,
.extra1 = &slow_work_min_threads,
.extra2 = (void *) &slow_work_max_max_threads,
},
{
.ctl_name = CTL_UNNUMBERED,
.procname = "vslow-percentage",
.data = &vslow_work_proportion,
.maxlen = sizeof(unsigned),
.mode = 0644,
.proc_handler = &proc_dointvec_minmax,
.extra1 = (void *) &slow_work_min_vslow,
.extra2 = (void *) &slow_work_max_vslow,
},
{ .ctl_name = 0 }
};
#endif
/*
* The active state of the thread pool
*/
static atomic_t slow_work_thread_count;
static atomic_t vslow_work_executing_count;
static bool slow_work_may_not_start_new_thread;
static bool slow_work_cull; /* cull a thread due to lack of activity */
static DEFINE_TIMER(slow_work_cull_timer, slow_work_cull_timeout, 0, 0);
static DEFINE_TIMER(slow_work_oom_timer, slow_work_oom_timeout, 0, 0);
static struct slow_work slow_work_new_thread; /* new thread starter */
/*
* The queues of work items and the lock governing access to them. These are
* shared between all the CPUs. It doesn't make sense to have per-CPU queues
* as the number of threads bears no relation to the number of CPUs.
*
* There are two queues of work items: one for slow work items, and one for
* very slow work items.
*/
static LIST_HEAD(slow_work_queue);
static LIST_HEAD(vslow_work_queue);
static DEFINE_SPINLOCK(slow_work_queue_lock);
/*
* The thread controls. A variable used to signal to the threads that they
* should exit when the queue is empty, a waitqueue used by the threads to wait
* for signals, and a completion set by the last thread to exit.
*/
static bool slow_work_threads_should_exit;
static DECLARE_WAIT_QUEUE_HEAD(slow_work_thread_wq);
static DECLARE_COMPLETION(slow_work_last_thread_exited);
/*
* The number of users of the thread pool and its lock. Whilst this is zero we
* have no threads hanging around, and when this reaches zero, we wait for all
* active or queued work items to complete and kill all the threads we do have.
*/
static int slow_work_user_count;
static DEFINE_MUTEX(slow_work_user_lock);
/*
* Calculate the maximum number of active threads in the pool that are
* permitted to process very slow work items.
*
* The answer is rounded up to at least 1, but may not equal or exceed the
* maximum number of the threads in the pool. This means we always have at
* least one thread that can process slow work items, and we always have at
* least one thread that won't get tied up doing so.
*/
static unsigned slow_work_calc_vsmax(void)
{
unsigned vsmax;
vsmax = atomic_read(&slow_work_thread_count) * vslow_work_proportion;
vsmax /= 100;
vsmax = max(vsmax, 1U);
return min(vsmax, slow_work_max_threads - 1);
}
/*
* Attempt to execute stuff queued on a slow thread. Return true if we managed
* it, false if there was nothing to do.
*/
static bool slow_work_execute(void)
{
struct slow_work *work = NULL;
unsigned vsmax;
bool very_slow;
vsmax = slow_work_calc_vsmax();
/* see if we can schedule a new thread to be started if we're not
* keeping up with the work */
if (!waitqueue_active(&slow_work_thread_wq) &&
(!list_empty(&slow_work_queue) || !list_empty(&vslow_work_queue)) &&
atomic_read(&slow_work_thread_count) < slow_work_max_threads &&
!slow_work_may_not_start_new_thread)
slow_work_enqueue(&slow_work_new_thread);
/* find something to execute */
spin_lock_irq(&slow_work_queue_lock);
if (!list_empty(&vslow_work_queue) &&
atomic_read(&vslow_work_executing_count) < vsmax) {
work = list_entry(vslow_work_queue.next,
struct slow_work, link);
if (test_and_set_bit_lock(SLOW_WORK_EXECUTING, &work->flags))
BUG();
list_del_init(&work->link);
atomic_inc(&vslow_work_executing_count);
very_slow = true;
} else if (!list_empty(&slow_work_queue)) {
work = list_entry(slow_work_queue.next,
struct slow_work, link);
if (test_and_set_bit_lock(SLOW_WORK_EXECUTING, &work->flags))
BUG();
list_del_init(&work->link);
very_slow = false;
} else {
very_slow = false; /* avoid the compiler warning */
}
spin_unlock_irq(&slow_work_queue_lock);
if (!work)
return false;
if (!test_and_clear_bit(SLOW_WORK_PENDING, &work->flags))
BUG();
work->ops->execute(work);
if (very_slow)
atomic_dec(&vslow_work_executing_count);
clear_bit_unlock(SLOW_WORK_EXECUTING, &work->flags);
/* if someone tried to enqueue the item whilst we were executing it,
* then it'll be left unenqueued to avoid multiple threads trying to
* execute it simultaneously
*
* there is, however, a race between us testing the pending flag and
* getting the spinlock, and between the enqueuer setting the pending
* flag and getting the spinlock, so we use a deferral bit to tell us
* if the enqueuer got there first
*/
if (test_bit(SLOW_WORK_PENDING, &work->flags)) {
spin_lock_irq(&slow_work_queue_lock);
if (!test_bit(SLOW_WORK_EXECUTING, &work->flags) &&
test_and_clear_bit(SLOW_WORK_ENQ_DEFERRED, &work->flags))
goto auto_requeue;
spin_unlock_irq(&slow_work_queue_lock);
}
work->ops->put_ref(work);
return true;
auto_requeue:
/* we must complete the enqueue operation
* - we transfer our ref on the item back to the appropriate queue
* - don't wake another thread up as we're awake already
*/
if (test_bit(SLOW_WORK_VERY_SLOW, &work->flags))
list_add_tail(&work->link, &vslow_work_queue);
else
list_add_tail(&work->link, &slow_work_queue);
spin_unlock_irq(&slow_work_queue_lock);
return true;
}
/**
* slow_work_enqueue - Schedule a slow work item for processing
* @work: The work item to queue
*
* Schedule a slow work item for processing. If the item is already undergoing
* execution, this guarantees not to re-enter the execution routine until the
* first execution finishes.
*
* The item is pinned by this function as it retains a reference to it, managed
* through the item operations. The item is unpinned once it has been
* executed.
*
* An item may hog the thread that is running it for a relatively large amount
* of time, sufficient, for example, to perform several lookup, mkdir, create
* and setxattr operations. It may sleep on I/O and may sleep to obtain locks.
*
* Conversely, if a number of items are awaiting processing, it may take some
* time before any given item is given attention. The number of threads in the
* pool may be increased to deal with demand, but only up to a limit.
*
* If SLOW_WORK_VERY_SLOW is set on the work item, then it will be placed in
* the very slow queue, from which only a portion of the threads will be
* allowed to pick items to execute. This ensures that very slow items won't
* overly block ones that are just ordinarily slow.
*
* Returns 0 if successful, -EAGAIN if not.
*/
int slow_work_enqueue(struct slow_work *work)
{
unsigned long flags;
BUG_ON(slow_work_user_count <= 0);
BUG_ON(!work);
BUG_ON(!work->ops);
BUG_ON(!work->ops->get_ref);
/* when honouring an enqueue request, we only promise that we will run
* the work function in the future; we do not promise to run it once
* per enqueue request
*
* we use the PENDING bit to merge together repeat requests without
* having to disable IRQs and take the spinlock, whilst still
* maintaining our promise
*/
if (!test_and_set_bit_lock(SLOW_WORK_PENDING, &work->flags)) {
spin_lock_irqsave(&slow_work_queue_lock, flags);
/* we promise that we will not attempt to execute the work
* function in more than one thread simultaneously
*
* this, however, leaves us with a problem if we're asked to
* enqueue the work whilst someone is executing the work
* function as simply queueing the work immediately means that
* another thread may try executing it whilst it is already
* under execution
*
* to deal with this, we set the ENQ_DEFERRED bit instead of
* enqueueing, and the thread currently executing the work
* function will enqueue the work item when the work function
* returns and it has cleared the EXECUTING bit
*/
if (test_bit(SLOW_WORK_EXECUTING, &work->flags)) {
set_bit(SLOW_WORK_ENQ_DEFERRED, &work->flags);
} else {
if (work->ops->get_ref(work) < 0)
goto cant_get_ref;
if (test_bit(SLOW_WORK_VERY_SLOW, &work->flags))
list_add_tail(&work->link, &vslow_work_queue);
else
list_add_tail(&work->link, &slow_work_queue);
wake_up(&slow_work_thread_wq);
}
spin_unlock_irqrestore(&slow_work_queue_lock, flags);
}
return 0;
cant_get_ref:
spin_unlock_irqrestore(&slow_work_queue_lock, flags);
return -EAGAIN;
}
EXPORT_SYMBOL(slow_work_enqueue);
/*
* Worker thread culling algorithm
*/
static bool slow_work_cull_thread(void)
{
unsigned long flags;
bool do_cull = false;
spin_lock_irqsave(&slow_work_queue_lock, flags);
if (slow_work_cull) {
slow_work_cull = false;
if (list_empty(&slow_work_queue) &&
list_empty(&vslow_work_queue) &&
atomic_read(&slow_work_thread_count) >
slow_work_min_threads) {
mod_timer(&slow_work_cull_timer,
jiffies + SLOW_WORK_CULL_TIMEOUT);
do_cull = true;
}
}
spin_unlock_irqrestore(&slow_work_queue_lock, flags);
return do_cull;
}
/*
* Determine if there is slow work available for dispatch
*/
static inline bool slow_work_available(int vsmax)
{
return !list_empty(&slow_work_queue) ||
(!list_empty(&vslow_work_queue) &&
atomic_read(&vslow_work_executing_count) < vsmax);
}
/*
* Worker thread dispatcher
*/
static int slow_work_thread(void *_data)
{
int vsmax;
DEFINE_WAIT(wait);
set_freezable();
set_user_nice(current, -5);
for (;;) {
vsmax = vslow_work_proportion;
vsmax *= atomic_read(&slow_work_thread_count);
vsmax /= 100;
prepare_to_wait(&slow_work_thread_wq, &wait,
TASK_INTERRUPTIBLE);
if (!freezing(current) &&
!slow_work_threads_should_exit &&
!slow_work_available(vsmax) &&
!slow_work_cull)
schedule();
finish_wait(&slow_work_thread_wq, &wait);
try_to_freeze();
vsmax = vslow_work_proportion;
vsmax *= atomic_read(&slow_work_thread_count);
vsmax /= 100;
if (slow_work_available(vsmax) && slow_work_execute()) {
cond_resched();
if (list_empty(&slow_work_queue) &&
list_empty(&vslow_work_queue) &&
atomic_read(&slow_work_thread_count) >
slow_work_min_threads)
mod_timer(&slow_work_cull_timer,
jiffies + SLOW_WORK_CULL_TIMEOUT);
continue;
}
if (slow_work_threads_should_exit)
break;
if (slow_work_cull && slow_work_cull_thread())
break;
}
if (atomic_dec_and_test(&slow_work_thread_count))
complete_and_exit(&slow_work_last_thread_exited, 0);
return 0;
}
/*
* Handle thread cull timer expiration
*/
static void slow_work_cull_timeout(unsigned long data)
{
slow_work_cull = true;
wake_up(&slow_work_thread_wq);
}
/*
* Get a reference on slow work thread starter
*/
static int slow_work_new_thread_get_ref(struct slow_work *work)
{
return 0;
}
/*
* Drop a reference on slow work thread starter
*/
static void slow_work_new_thread_put_ref(struct slow_work *work)
{
}
/*
* Start a new slow work thread
*/
static void slow_work_new_thread_execute(struct slow_work *work)
{
struct task_struct *p;
if (slow_work_threads_should_exit)
return;
if (atomic_read(&slow_work_thread_count) >= slow_work_max_threads)
return;
if (!mutex_trylock(&slow_work_user_lock))
return;
slow_work_may_not_start_new_thread = true;
atomic_inc(&slow_work_thread_count);
p = kthread_run(slow_work_thread, NULL, "kslowd");
if (IS_ERR(p)) {
printk(KERN_DEBUG "Slow work thread pool: OOM\n");
if (atomic_dec_and_test(&slow_work_thread_count))
BUG(); /* we're running on a slow work thread... */
mod_timer(&slow_work_oom_timer,
jiffies + SLOW_WORK_OOM_TIMEOUT);
} else {
/* ratelimit the starting of new threads */
mod_timer(&slow_work_oom_timer, jiffies + 1);
}
mutex_unlock(&slow_work_user_lock);
}
static const struct slow_work_ops slow_work_new_thread_ops = {
.get_ref = slow_work_new_thread_get_ref,
.put_ref = slow_work_new_thread_put_ref,
.execute = slow_work_new_thread_execute,
};
/*
* post-OOM new thread start suppression expiration
*/
static void slow_work_oom_timeout(unsigned long data)
{
slow_work_may_not_start_new_thread = false;
}
#ifdef CONFIG_SYSCTL
/*
* Handle adjustment of the minimum number of threads
*/
static int slow_work_min_threads_sysctl(struct ctl_table *table, int write,
struct file *filp, void __user *buffer,
size_t *lenp, loff_t *ppos)
{
int ret = proc_dointvec_minmax(table, write, filp, buffer, lenp, ppos);
int n;
if (ret == 0) {
mutex_lock(&slow_work_user_lock);
if (slow_work_user_count > 0) {
/* see if we need to start or stop threads */
n = atomic_read(&slow_work_thread_count) -
slow_work_min_threads;
if (n < 0 && !slow_work_may_not_start_new_thread)
slow_work_enqueue(&slow_work_new_thread);
else if (n > 0)
mod_timer(&slow_work_cull_timer,
jiffies + SLOW_WORK_CULL_TIMEOUT);
}
mutex_unlock(&slow_work_user_lock);
}
return ret;
}
/*
* Handle adjustment of the maximum number of threads
*/
static int slow_work_max_threads_sysctl(struct ctl_table *table, int write,
struct file *filp, void __user *buffer,
size_t *lenp, loff_t *ppos)
{
int ret = proc_dointvec_minmax(table, write, filp, buffer, lenp, ppos);
int n;
if (ret == 0) {
mutex_lock(&slow_work_user_lock);
if (slow_work_user_count > 0) {
/* see if we need to stop threads */
n = slow_work_max_threads -
atomic_read(&slow_work_thread_count);
if (n < 0)
mod_timer(&slow_work_cull_timer,
jiffies + SLOW_WORK_CULL_TIMEOUT);
}
mutex_unlock(&slow_work_user_lock);
}
return ret;
}
#endif /* CONFIG_SYSCTL */
/**
* slow_work_register_user - Register a user of the facility
*
* Register a user of the facility, starting up the initial threads if there
* aren't any other users at this point. This will return 0 if successful, or
* an error if not.
*/
int slow_work_register_user(void)
{
struct task_struct *p;
int loop;
mutex_lock(&slow_work_user_lock);
if (slow_work_user_count == 0) {
printk(KERN_NOTICE "Slow work thread pool: Starting up\n");
init_completion(&slow_work_last_thread_exited);
slow_work_threads_should_exit = false;
slow_work_init(&slow_work_new_thread,
&slow_work_new_thread_ops);
slow_work_may_not_start_new_thread = false;
slow_work_cull = false;
/* start the minimum number of threads */
for (loop = 0; loop < slow_work_min_threads; loop++) {
atomic_inc(&slow_work_thread_count);
p = kthread_run(slow_work_thread, NULL, "kslowd");
if (IS_ERR(p))
goto error;
}
printk(KERN_NOTICE "Slow work thread pool: Ready\n");
}
slow_work_user_count++;
mutex_unlock(&slow_work_user_lock);
return 0;
error:
if (atomic_dec_and_test(&slow_work_thread_count))
complete(&slow_work_last_thread_exited);
if (loop > 0) {
printk(KERN_ERR "Slow work thread pool:"
" Aborting startup on ENOMEM\n");
slow_work_threads_should_exit = true;
wake_up_all(&slow_work_thread_wq);
wait_for_completion(&slow_work_last_thread_exited);
printk(KERN_ERR "Slow work thread pool: Aborted\n");
}
mutex_unlock(&slow_work_user_lock);
return PTR_ERR(p);
}
EXPORT_SYMBOL(slow_work_register_user);
/**
* slow_work_unregister_user - Unregister a user of the facility
*
* Unregister a user of the facility, killing all the threads if this was the
* last one.
*/
void slow_work_unregister_user(void)
{
mutex_lock(&slow_work_user_lock);
BUG_ON(slow_work_user_count <= 0);
slow_work_user_count--;
if (slow_work_user_count == 0) {
printk(KERN_NOTICE "Slow work thread pool: Shutting down\n");
slow_work_threads_should_exit = true;
wake_up_all(&slow_work_thread_wq);
wait_for_completion(&slow_work_last_thread_exited);
printk(KERN_NOTICE "Slow work thread pool:"
" Shut down complete\n");
}
del_timer_sync(&slow_work_cull_timer);
mutex_unlock(&slow_work_user_lock);
}
EXPORT_SYMBOL(slow_work_unregister_user);
/*
* Initialise the slow work facility
*/
static int __init init_slow_work(void)
{
unsigned nr_cpus = num_possible_cpus();
if (slow_work_max_threads < nr_cpus)
slow_work_max_threads = nr_cpus;
#ifdef CONFIG_SYSCTL
if (slow_work_max_max_threads < nr_cpus * 2)
slow_work_max_max_threads = nr_cpus * 2;
#endif
return 0;
}
subsys_initcall(init_slow_work);

9
kernel/sysctl.c
View File

@ -48,6 +48,7 @@
#include <linux/acpi.h>
#include <linux/reboot.h>
#include <linux/ftrace.h>
#include <linux/slow-work.h>
#include <asm/uaccess.h>
#include <asm/processor.h>
@ -897,6 +898,14 @@ static struct ctl_table kern_table[] = {
.proc_handler = &scan_unevictable_handler,
},
#endif
#ifdef CONFIG_SLOW_WORK
{
.ctl_name = CTL_UNNUMBERED,
.procname = "slow-work",
.mode = 0555,
.child = slow_work_sysctls,
},
#endif
/*
* NOTE: do not add new entries to this table unless you have read
* Documentation/sysctl/ctl_unnumbered.txt

21
mm/filemap.c
View File

@ -564,6 +564,24 @@ void wait_on_page_bit(struct page *page, int bit_nr)
}
EXPORT_SYMBOL(wait_on_page_bit);
/**
* add_page_wait_queue - Add an arbitrary waiter to a page's wait queue
* @page - Page defining the wait queue of interest
* @waiter - Waiter to add to the queue
*
* Add an arbitrary @waiter to the wait queue for the nominated @page.
*/
void add_page_wait_queue(struct page *page, wait_queue_t *waiter)
{
wait_queue_head_t *q = page_waitqueue(page);
unsigned long flags;
spin_lock_irqsave(&q->lock, flags);
__add_wait_queue(q, waiter);
spin_unlock_irqrestore(&q->lock, flags);
}
EXPORT_SYMBOL_GPL(add_page_wait_queue);
/**
* unlock_page - unlock a locked page
* @page: the page
@ -2463,6 +2481,9 @@ EXPORT_SYMBOL(generic_file_aio_write);
* (presumably at page->private). If the release was successful, return `1'.
* Otherwise return zero.
*
* This may also be called if PG_fscache is set on a page, indicating that the
* page is known to the local caching routines.
*
* The @gfp_mask argument specifies whether I/O may be performed to release
* this page (__GFP_IO), and whether the call may block (__GFP_WAIT & __GFP_FS).
*

10
mm/migrate.c
View File

@ -250,7 +250,7 @@ void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd,
* The number of remaining references must be:
* 1 for anonymous pages without a mapping
* 2 for pages with a mapping
* 3 for pages with a mapping and PagePrivate set.
* 3 for pages with a mapping and PagePrivate/PagePrivate2 set.
*/
static int migrate_page_move_mapping(struct address_space *mapping,
struct page *newpage, struct page *page)
@ -270,7 +270,7 @@ static int migrate_page_move_mapping(struct address_space *mapping,
pslot = radix_tree_lookup_slot(&mapping->page_tree,
page_index(page));
expected_count = 2 + !!PagePrivate(page);
expected_count = 2 + !!page_has_private(page);
if (page_count(page) != expected_count ||
(struct page *)radix_tree_deref_slot(pslot) != page) {
spin_unlock_irq(&mapping->tree_lock);
@ -386,7 +386,7 @@ EXPORT_SYMBOL(fail_migrate_page);
/*
* Common logic to directly migrate a single page suitable for
* pages that do not use PagePrivate.
* pages that do not use PagePrivate/PagePrivate2.
*
* Pages are locked upon entry and exit.
*/
@ -522,7 +522,7 @@ static int fallback_migrate_page(struct address_space *mapping,
* Buffers may be managed in a filesystem specific way.
* We must have no buffers or drop them.
*/
if (PagePrivate(page) &&
if (page_has_private(page) &&
!try_to_release_page(page, GFP_KERNEL))
return -EAGAIN;
@ -655,7 +655,7 @@ static int unmap_and_move(new_page_t get_new_page, unsigned long private,
* free the metadata, so the page can be freed.
*/
if (!page->mapping) {
if (!PageAnon(page) && PagePrivate(page)) {
if (!PageAnon(page) && page_has_private(page)) {
/*
* Go direct to try_to_free_buffers() here because
* a) that's what try_to_release_page() would do anyway

40
mm/readahead.c
View File

@ -31,6 +31,42 @@ EXPORT_SYMBOL_GPL(file_ra_state_init);
#define list_to_page(head) (list_entry((head)->prev, struct page, lru))
/*
* see if a page needs releasing upon read_cache_pages() failure
* - the caller of read_cache_pages() may have set PG_private or PG_fscache
* before calling, such as the NFS fs marking pages that are cached locally
* on disk, thus we need to give the fs a chance to clean up in the event of
* an error
*/
static void read_cache_pages_invalidate_page(struct address_space *mapping,
struct page *page)
{
if (page_has_private(page)) {
if (!trylock_page(page))
BUG();
page->mapping = mapping;
do_invalidatepage(page, 0);
page->mapping = NULL;
unlock_page(page);
}
page_cache_release(page);
}
/*
* release a list of pages, invalidating them first if need be
*/
static void read_cache_pages_invalidate_pages(struct address_space *mapping,
struct list_head *pages)
{
struct page *victim;
while (!list_empty(pages)) {
victim = list_to_page(pages);
list_del(&victim->lru);
read_cache_pages_invalidate_page(mapping, victim);
}
}
/**
* read_cache_pages - populate an address space with some pages & start reads against them
* @mapping: the address_space
@ -52,14 +88,14 @@ int read_cache_pages(struct address_space *mapping, struct list_head *pages,
list_del(&page->lru);
if (add_to_page_cache_lru(page, mapping,
page->index, GFP_KERNEL)) {
page_cache_release(page);
read_cache_pages_invalidate_page(mapping, page);
continue;
}
page_cache_release(page);
ret = filler(data, page);
if (unlikely(ret)) {
put_pages_list(pages);
read_cache_pages_invalidate_pages(mapping, pages);
break;
}
task_io_account_read(PAGE_CACHE_SIZE);

4
mm/swap.c
View File

@ -448,8 +448,8 @@ void pagevec_strip(struct pagevec *pvec)
for (i = 0; i < pagevec_count(pvec); i++) {
struct page *page = pvec->pages[i];
if (PagePrivate(page) && trylock_page(page)) {
if (PagePrivate(page))
if (page_has_private(page) && trylock_page(page)) {
if (page_has_private(page))
try_to_release_page(page, 0);
unlock_page(page);
}

10
mm/truncate.c
View File

@ -50,7 +50,7 @@ void do_invalidatepage(struct page *page, unsigned long offset)
static inline void truncate_partial_page(struct page *page, unsigned partial)
{
zero_user_segment(page, partial, PAGE_CACHE_SIZE);
if (PagePrivate(page))
if (page_has_private(page))
do_invalidatepage(page, partial);
}
@ -99,7 +99,7 @@ truncate_complete_page(struct address_space *mapping, struct page *page)
if (page->mapping != mapping)
return;
if (PagePrivate(page))
if (page_has_private(page))
do_invalidatepage(page, 0);
cancel_dirty_page(page, PAGE_CACHE_SIZE);
@ -126,7 +126,7 @@ invalidate_complete_page(struct address_space *mapping, struct page *page)
if (page->mapping != mapping)
return 0;
if (PagePrivate(page) && !try_to_release_page(page, 0))
if (page_has_private(page) && !try_to_release_page(page, 0))
return 0;
clear_page_mlock(page);
@ -348,7 +348,7 @@ invalidate_complete_page2(struct address_space *mapping, struct page *page)
if (page->mapping != mapping)
return 0;
if (PagePrivate(page) && !try_to_release_page(page, GFP_KERNEL))
if (page_has_private(page) && !try_to_release_page(page, GFP_KERNEL))
return 0;
spin_lock_irq(&mapping->tree_lock);
@ -356,7 +356,7 @@ invalidate_complete_page2(struct address_space *mapping, struct page *page)
goto failed;
clear_page_mlock(page);
BUG_ON(PagePrivate(page));
BUG_ON(page_has_private(page));
__remove_from_page_cache(page);
spin_unlock_irq(&mapping->tree_lock);
page_cache_release(page); /* pagecache ref */

6
mm/vmscan.c
View File

@ -283,7 +283,7 @@ static inline int page_mapping_inuse(struct page *page)
static inline int is_page_cache_freeable(struct page *page)
{
return page_count(page) - !!PagePrivate(page) == 2;
return page_count(page) - !!page_has_private(page) == 2;
}
static int may_write_to_queue(struct backing_dev_info *bdi)
@ -367,7 +367,7 @@ static pageout_t pageout(struct page *page, struct address_space *mapping,
* Some data journaling orphaned pages can have
* page->mapping == NULL while being dirty with clean buffers.
*/
if (PagePrivate(page)) {
if (page_has_private(page)) {
if (try_to_free_buffers(page)) {
ClearPageDirty(page);
printk("%s: orphaned page\n", __func__);
@ -727,7 +727,7 @@ static unsigned long shrink_page_list(struct list_head *page_list,
* process address space (page_count == 1) it can be freed.
* Otherwise, leave the page on the LRU so it is swappable.
*/
if (PagePrivate(page)) {
if (page_has_private(page)) {
if (!try_to_release_page(page, sc->gfp_mask))
goto activate_locked;
if (!mapping && page_count(page) == 1) {

2
security/security.c
View File

@ -445,6 +445,7 @@ int security_inode_create(struct inode *dir, struct dentry *dentry, int mode)
return 0;
return security_ops->inode_create(dir, dentry, mode);
}
EXPORT_SYMBOL_GPL(security_inode_create);
int security_inode_link(struct dentry *old_dentry, struct inode *dir,
struct dentry *new_dentry)
@ -475,6 +476,7 @@ int security_inode_mkdir(struct inode *dir, struct dentry *dentry, int mode)
return 0;
return security_ops->inode_mkdir(dir, dentry, mode);
}
EXPORT_SYMBOL_GPL(security_inode_mkdir);
int security_inode_rmdir(struct inode *dir, struct dentry *dentry)
{