Commit Graph

483 Commits

Author SHA1 Message Date
Long Li
8c5f9c1ab7 CIFS: Add support for direct I/O write
With direct I/O write, user supplied buffers are pinned to the memory and data
are transferred directly from user buffers to the transport layer.

Change in v3: add support for kernel AIO

Change in v4:
Refactor common write code to __cifs_writev for direct and non-direct I/O.
Retry on direct I/O failure.

Signed-off-by: Long Li <longli@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
2018-11-02 14:09:42 -05:00
Long Li
6e6e2b86c2 CIFS: Add support for direct I/O read
With direct I/O read, we transfer the data directly from transport layer to
the user data buffer.

Change in v3: add support for kernel AIO

Change in v4:
Refactor common read code to __cifs_readv for direct and non-direct I/O.
Retry on direct I/O failure.

Signed-off-by: Long Li <longli@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
2018-11-02 14:09:41 -05:00
Colin Ian King
413d610081 cifs: fix spelling mistake, EACCESS -> EACCES
Trivial fix to a spelling mistake of the error access name EACCESS,
rename to EACCES

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
2018-11-02 14:09:41 -05:00
Linus Torvalds
9931a07d51 Merge branch 'work.afs' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull AFS updates from Al Viro:
 "AFS series, with some iov_iter bits included"

* 'work.afs' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (26 commits)
  missing bits of "iov_iter: Separate type from direction and use accessor functions"
  afs: Probe multiple fileservers simultaneously
  afs: Fix callback handling
  afs: Eliminate the address pointer from the address list cursor
  afs: Allow dumping of server cursor on operation failure
  afs: Implement YFS support in the fs client
  afs: Expand data structure fields to support YFS
  afs: Get the target vnode in afs_rmdir() and get a callback on it
  afs: Calc callback expiry in op reply delivery
  afs: Fix FS.FetchStatus delivery from updating wrong vnode
  afs: Implement the YFS cache manager service
  afs: Remove callback details from afs_callback_break struct
  afs: Commit the status on a new file/dir/symlink
  afs: Increase to 64-bit volume ID and 96-bit vnode ID for YFS
  afs: Don't invoke the server to read data beyond EOF
  afs: Add a couple of tracepoints to log I/O errors
  afs: Handle EIO from delivery function
  afs: Fix TTL on VL server and address lists
  afs: Implement VL server rotation
  afs: Improve FS server rotation error handling
  ...
2018-11-01 19:58:52 -07:00
Steve French
fae8044c03 smb3: show number of current open files in /proc/fs/cifs/Stats
To allow better debugging (for example applications with
handle leaks, or complex reconnect scenarios) display the
number of open files (on the client) and number of open
server file handles for each tcon in /proc/fs/cifs/Stats.
Note that open files on server is one larger than local
due to handle caching (in this case of the root of
the share).  In this example there are two local
open files, and three (two file and one directory handle)
open on the server.

Sample output:

$ cat /proc/fs/cifs/Stats
Resources in use
CIFS Session: 1
Share (unique mount targets): 2
SMB Request/Response Buffer: 1 Pool size: 5
SMB Small Req/Resp Buffer: 1 Pool size: 30
Operations (MIDs): 0

0 session 0 share reconnects
Total vfs operations: 36 maximum at one time: 2

1) \\localhost\test
SMBs: 69
Bytes read: 27  Bytes written: 0
Open files: 2 total (local), 3 open on server
TreeConnects: 1 total 0 failed
TreeDisconnects: 0 total 0 failed
Creates: 19 total 0 failed
Closes: 16 total 0 failed
...

Signed-off-by: Steve French <stfrench@microsoft.com>
2018-10-23 21:16:06 -05:00
Steve French
0cb012d1a0 cifs: track writepages in vfs operation counters
writepages and readpages operations did not call get/free_xid
so the statistics for file copy could get confusing with "vfs operations"
not increasing.  Add get_xid and free_xid to cifs readpages and
writepages functions.

Signed-off-by: Steve French <stfrench@microsoft.com>
Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com>
2018-10-23 21:16:05 -05:00
Ronnie Sahlberg
9645759ce6 cifs: OFD locks do not conflict with eachothers
RHBZ 1484130

Update cifs_find_fid_lock_conflict() to recognize that
ODF locks do not conflict with eachother.

Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
2018-10-23 21:16:05 -05:00
Steve French
9b9c5bea0b cifs: do not return atime less than mtime
In network file system it is fairly easy for server and client
atime vs. mtime to get confused (and atime updated less frequently)
which we noticed broke some apps which expect atime >= mtime

Also ignore relatime mount option (rather than error on it) since
relatime is basically what some network server fs are doing
(relatime).

Signed-off-by: Steve French <stfrench@microsoft.com>
Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com>
2018-10-23 21:16:05 -05:00
David Howells
00e2370744 iov_iter: Use accessor function
Use accessor functions to access an iterator's type and direction.  This
allows for the possibility of using some other method of determining the
type of iterator than if-chains with bitwise-AND conditions.

Signed-off-by: David Howells <dhowells@redhat.com>
2018-10-24 00:40:44 +01:00
Kees Cook
6396bb2215 treewide: kzalloc() -> kcalloc()
The kzalloc() function has a 2-factor argument form, kcalloc(). This
patch replaces cases of:

        kzalloc(a * b, gfp)

with:
        kcalloc(a * b, gfp)

as well as handling cases of:

        kzalloc(a * b * c, gfp)

with:

        kzalloc(array3_size(a, b, c), gfp)

as it's slightly less ugly than:

        kzalloc_array(array_size(a, b), c, gfp)

This does, however, attempt to ignore constant size factors like:

        kzalloc(4 * 1024, gfp)

though any constants defined via macros get caught up in the conversion.

Any factors with a sizeof() of "unsigned char", "char", and "u8" were
dropped, since they're redundant.

The Coccinelle script used for this was:

// Fix redundant parens around sizeof().
@@
type TYPE;
expression THING, E;
@@

(
  kzalloc(
-	(sizeof(TYPE)) * E
+	sizeof(TYPE) * E
  , ...)
|
  kzalloc(
-	(sizeof(THING)) * E
+	sizeof(THING) * E
  , ...)
)

// Drop single-byte sizes and redundant parens.
@@
expression COUNT;
typedef u8;
typedef __u8;
@@

(
  kzalloc(
-	sizeof(u8) * (COUNT)
+	COUNT
  , ...)
|
  kzalloc(
-	sizeof(__u8) * (COUNT)
+	COUNT
  , ...)
|
  kzalloc(
-	sizeof(char) * (COUNT)
+	COUNT
  , ...)
|
  kzalloc(
-	sizeof(unsigned char) * (COUNT)
+	COUNT
  , ...)
|
  kzalloc(
-	sizeof(u8) * COUNT
+	COUNT
  , ...)
|
  kzalloc(
-	sizeof(__u8) * COUNT
+	COUNT
  , ...)
|
  kzalloc(
-	sizeof(char) * COUNT
+	COUNT
  , ...)
|
  kzalloc(
-	sizeof(unsigned char) * COUNT
+	COUNT
  , ...)
)

// 2-factor product with sizeof(type/expression) and identifier or constant.
@@
type TYPE;
expression THING;
identifier COUNT_ID;
constant COUNT_CONST;
@@

(
- kzalloc
+ kcalloc
  (
-	sizeof(TYPE) * (COUNT_ID)
+	COUNT_ID, sizeof(TYPE)
  , ...)
|
- kzalloc
+ kcalloc
  (
-	sizeof(TYPE) * COUNT_ID
+	COUNT_ID, sizeof(TYPE)
  , ...)
|
- kzalloc
+ kcalloc
  (
-	sizeof(TYPE) * (COUNT_CONST)
+	COUNT_CONST, sizeof(TYPE)
  , ...)
|
- kzalloc
+ kcalloc
  (
-	sizeof(TYPE) * COUNT_CONST
+	COUNT_CONST, sizeof(TYPE)
  , ...)
|
- kzalloc
+ kcalloc
  (
-	sizeof(THING) * (COUNT_ID)
+	COUNT_ID, sizeof(THING)
  , ...)
|
- kzalloc
+ kcalloc
  (
-	sizeof(THING) * COUNT_ID
+	COUNT_ID, sizeof(THING)
  , ...)
|
- kzalloc
+ kcalloc
  (
-	sizeof(THING) * (COUNT_CONST)
+	COUNT_CONST, sizeof(THING)
  , ...)
|
- kzalloc
+ kcalloc
  (
-	sizeof(THING) * COUNT_CONST
+	COUNT_CONST, sizeof(THING)
  , ...)
)

// 2-factor product, only identifiers.
@@
identifier SIZE, COUNT;
@@

- kzalloc
+ kcalloc
  (
-	SIZE * COUNT
+	COUNT, SIZE
  , ...)

// 3-factor product with 1 sizeof(type) or sizeof(expression), with
// redundant parens removed.
@@
expression THING;
identifier STRIDE, COUNT;
type TYPE;
@@

(
  kzalloc(
-	sizeof(TYPE) * (COUNT) * (STRIDE)
+	array3_size(COUNT, STRIDE, sizeof(TYPE))
  , ...)
|
  kzalloc(
-	sizeof(TYPE) * (COUNT) * STRIDE
+	array3_size(COUNT, STRIDE, sizeof(TYPE))
  , ...)
|
  kzalloc(
-	sizeof(TYPE) * COUNT * (STRIDE)
+	array3_size(COUNT, STRIDE, sizeof(TYPE))
  , ...)
|
  kzalloc(
-	sizeof(TYPE) * COUNT * STRIDE
+	array3_size(COUNT, STRIDE, sizeof(TYPE))
  , ...)
|
  kzalloc(
-	sizeof(THING) * (COUNT) * (STRIDE)
+	array3_size(COUNT, STRIDE, sizeof(THING))
  , ...)
|
  kzalloc(
-	sizeof(THING) * (COUNT) * STRIDE
+	array3_size(COUNT, STRIDE, sizeof(THING))
  , ...)
|
  kzalloc(
-	sizeof(THING) * COUNT * (STRIDE)
+	array3_size(COUNT, STRIDE, sizeof(THING))
  , ...)
|
  kzalloc(
-	sizeof(THING) * COUNT * STRIDE
+	array3_size(COUNT, STRIDE, sizeof(THING))
  , ...)
)

// 3-factor product with 2 sizeof(variable), with redundant parens removed.
@@
expression THING1, THING2;
identifier COUNT;
type TYPE1, TYPE2;
@@

(
  kzalloc(
-	sizeof(TYPE1) * sizeof(TYPE2) * COUNT
+	array3_size(COUNT, sizeof(TYPE1), sizeof(TYPE2))
  , ...)
|
  kzalloc(
-	sizeof(TYPE1) * sizeof(THING2) * (COUNT)
+	array3_size(COUNT, sizeof(TYPE1), sizeof(TYPE2))
  , ...)
|
  kzalloc(
-	sizeof(THING1) * sizeof(THING2) * COUNT
+	array3_size(COUNT, sizeof(THING1), sizeof(THING2))
  , ...)
|
  kzalloc(
-	sizeof(THING1) * sizeof(THING2) * (COUNT)
+	array3_size(COUNT, sizeof(THING1), sizeof(THING2))
  , ...)
|
  kzalloc(
-	sizeof(TYPE1) * sizeof(THING2) * COUNT
+	array3_size(COUNT, sizeof(TYPE1), sizeof(THING2))
  , ...)
|
  kzalloc(
-	sizeof(TYPE1) * sizeof(THING2) * (COUNT)
+	array3_size(COUNT, sizeof(TYPE1), sizeof(THING2))
  , ...)
)

// 3-factor product, only identifiers, with redundant parens removed.
@@
identifier STRIDE, SIZE, COUNT;
@@

(
  kzalloc(
-	(COUNT) * STRIDE * SIZE
+	array3_size(COUNT, STRIDE, SIZE)
  , ...)
|
  kzalloc(
-	COUNT * (STRIDE) * SIZE
+	array3_size(COUNT, STRIDE, SIZE)
  , ...)
|
  kzalloc(
-	COUNT * STRIDE * (SIZE)
+	array3_size(COUNT, STRIDE, SIZE)
  , ...)
|
  kzalloc(
-	(COUNT) * (STRIDE) * SIZE
+	array3_size(COUNT, STRIDE, SIZE)
  , ...)
|
  kzalloc(
-	COUNT * (STRIDE) * (SIZE)
+	array3_size(COUNT, STRIDE, SIZE)
  , ...)
|
  kzalloc(
-	(COUNT) * STRIDE * (SIZE)
+	array3_size(COUNT, STRIDE, SIZE)
  , ...)
|
  kzalloc(
-	(COUNT) * (STRIDE) * (SIZE)
+	array3_size(COUNT, STRIDE, SIZE)
  , ...)
|
  kzalloc(
-	COUNT * STRIDE * SIZE
+	array3_size(COUNT, STRIDE, SIZE)
  , ...)
)

// Any remaining multi-factor products, first at least 3-factor products,
// when they're not all constants...
@@
expression E1, E2, E3;
constant C1, C2, C3;
@@

(
  kzalloc(C1 * C2 * C3, ...)
|
  kzalloc(
-	(E1) * E2 * E3
+	array3_size(E1, E2, E3)
  , ...)
|
  kzalloc(
-	(E1) * (E2) * E3
+	array3_size(E1, E2, E3)
  , ...)
|
  kzalloc(
-	(E1) * (E2) * (E3)
+	array3_size(E1, E2, E3)
  , ...)
|
  kzalloc(
-	E1 * E2 * E3
+	array3_size(E1, E2, E3)
  , ...)
)

// And then all remaining 2 factors products when they're not all constants,
// keeping sizeof() as the second factor argument.
@@
expression THING, E1, E2;
type TYPE;
constant C1, C2, C3;
@@

(
  kzalloc(sizeof(THING) * C2, ...)
|
  kzalloc(sizeof(TYPE) * C2, ...)
|
  kzalloc(C1 * C2 * C3, ...)
|
  kzalloc(C1 * C2, ...)
|
- kzalloc
+ kcalloc
  (
-	sizeof(TYPE) * (E2)
+	E2, sizeof(TYPE)
  , ...)
|
- kzalloc
+ kcalloc
  (
-	sizeof(TYPE) * E2
+	E2, sizeof(TYPE)
  , ...)
|
- kzalloc
+ kcalloc
  (
-	sizeof(THING) * (E2)
+	E2, sizeof(THING)
  , ...)
|
- kzalloc
+ kcalloc
  (
-	sizeof(THING) * E2
+	E2, sizeof(THING)
  , ...)
|
- kzalloc
+ kcalloc
  (
-	(E1) * E2
+	E1, E2
  , ...)
|
- kzalloc
+ kcalloc
  (
-	(E1) * (E2)
+	E1, E2
  , ...)
|
- kzalloc
+ kcalloc
  (
-	E1 * E2
+	E1, E2
  , ...)
)

Signed-off-by: Kees Cook <keescook@chromium.org>
2018-06-12 16:19:22 -07:00
Long Li
1dbe3466b4 CIFS: Use offset when reading pages
With offset defined in rdata, transport functions need to look at this
offset when reading data into the correct places in pages.

Signed-off-by: Long Li <longli@microsoft.com>
Signed-off-by: Steve French <smfrench@gmail.com>
2018-06-02 18:36:26 -05:00
Long Li
f9f5aca115 CIFS: Add support for direct pages in rdata
Add a function to allocate rdata without allocating pages for data
transfer. This gives the caller an option to pass a number of pages
that point to the data buffer.

rdata is still reponsible for free those pages after it's done.

Signed-off-by: Long Li <longli@microsoft.com>
Signed-off-by: Steve French <smfrench@gmail.com>
2018-06-02 18:36:26 -05:00
Souptick Joarder
a5240cbde2 fs: cifs: Adding new return type vm_fault_t
Use new return type vm_fault_t for page_mkwrite
handler.

Signed-off-by: Souptick Joarder <jrdr.linux@gmail.com>
Reviewed-by: Matthew Wilcox <mawilcox@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
2018-04-17 14:44:35 -05:00
Matthew Wilcox
b93b016313 page cache: use xa_lock
Remove the address_space ->tree_lock and use the xa_lock newly added to
the radix_tree_root.  Rename the address_space ->page_tree to ->i_pages,
since we don't really care that it's a tree.

[willy@infradead.org: fix nds32, fs/dax.c]
  Link: http://lkml.kernel.org/r/20180406145415.GB20605@bombadil.infradead.orgLink: http://lkml.kernel.org/r/20180313132639.17387-9-willy@infradead.org
Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
Acked-by: Jeff Layton <jlayton@redhat.com>
Cc: Darrick J. Wong <darrick.wong@oracle.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-04-11 10:28:39 -07:00
Long Li
bd3dcc6a22 CIFS: SMBD: Upper layer performs SMB read via RDMA write through memory registration
If I/O size is larger than rdma_readwrite_threshold, use RDMA write for
SMB read by specifying channel SMB2_CHANNEL_RDMA_V1 or
SMB2_CHANNEL_RDMA_V1_INVALIDATE in the SMB packet, depending on SMB dialect
used. Append a smbd_buffer_descriptor_v1 to the end of the SMB packet and fill
in other values to indicate this SMB read uses RDMA write.

There is no need to read from the transport for incoming payload. At the time
SMB read response comes back, the data is already transferred and placed in the
pages by RDMA hardware.

When SMB read is finished, deregister the memory regions if RDMA write is used
for this SMB read. smbd_deregister_mr may need to do local invalidation and
sleep, if server remote invalidation is not used.

There are situations where the MID may not be created on I/O failure, under
which memory region is deregistered when read data context is released.

Signed-off-by: Long Li <longli@microsoft.com>
Signed-off-by: Steve French <smfrench@gmail.com>
Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>
Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com>
2018-01-24 19:49:07 -06:00
Matthew Wilcox
f04a703c3d cifs: Fix missing put_xid in cifs_file_strict_mmap
If cifs_zap_mapping() returned an error, we would return without putting
the xid that we got earlier.  Restructure cifs_file_strict_mmap() and
cifs_file_mmap() to be more similar to each other and have a single
point of return that always puts the xid.

Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
Signed-off-by: Steve French <smfrench@gmail.com>
CC: Stable <stable@vger.kernel.org>
2018-01-24 19:49:06 -06:00
Jan Kara
9c19a9cb16 cifs: use find_get_pages_range_tag()
wdata_alloc_and_fillpages() needlessly iterates calls to
find_get_pages_tag().  Also it wants only pages from given range.  Make
it use find_get_pages_range_tag().

Link: http://lkml.kernel.org/r/20171009151359.31984-17-jack@suse.cz
Signed-off-by: Jan Kara <jack@suse.cz>
Suggested-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Reviewed-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Cc: Steve French <sfrench@samba.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-11-15 18:21:04 -08:00
Steve French
1013e760d1 SMB3: Don't ignore O_SYNC/O_DSYNC and O_DIRECT flags
Signed-off-by: Steve French <smfrench@gmail.com>
CC: Stable <stable@vger.kernel.org>
Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com>
Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>
2017-09-22 19:47:17 -05:00
Colin Ian King
4d61eda812 CIFS: make arrays static const, reduces object code size
Don't populate the read-only arrays types[] on the stack, instead make
them both static const.  Makes the object code smaller by over 200 bytes:

Before:
   text	   data	    bss	    dec	    hex	filename
 111503	  37696	    448	 149647	  2488f	fs/cifs/file.o

After:
   text	   data	    bss	    dec	    hex	filename
 111140	  37856	    448	 149444	  247c4	fs/cifs/file.o

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Steve French <smfrench@gmail.com>
Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com>
2017-09-20 18:46:10 -05:00
Jeff Layton
3b49c9a1e9 fs: convert a pile of fsync routines to errseq_t based reporting
This patch converts most of the in-kernel filesystems that do writeback
out of the pagecache to report errors using the errseq_t-based
infrastructure that was recently added. This allows them to report
errors once for each open file description.

Most filesystems have a fairly straightforward fsync operation. They
call filemap_write_and_wait_range to write back all of the data and
wait on it, and then (sometimes) sync out the metadata.

For those filesystems this is a straightforward conversion from calling
filemap_write_and_wait_range in their fsync operation to calling
file_write_and_wait_range.

Acked-by: Jan Kara <jack@suse.cz>
Acked-by: Dave Kleikamp <dave.kleikamp@oracle.com>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
2017-08-01 08:39:29 -04:00
Rabin Vincent
966681c9f0 CIFS: fix circular locking dependency
When a CIFS filesystem is mounted with the forcemand option and the
following command is run on it, lockdep warns about a circular locking
dependency between CifsInodeInfo::lock_sem and the inode lock.

 while echo foo > hello; do :; done & while touch -c hello; do :; done

cifs_writev() takes the locks in the wrong order, but note that we can't
only flip the order around because it releases the inode lock before the
call to generic_write_sync() while it holds the lock_sem across that
call.

But, AFAICS, there is no need to hold the CifsInodeInfo::lock_sem across
the generic_write_sync() call either, so we can release both the locks
before generic_write_sync(), and change the order.

 ======================================================
 WARNING: possible circular locking dependency detected
 4.12.0-rc7+ #9 Not tainted
 ------------------------------------------------------
 touch/487 is trying to acquire lock:
  (&cifsi->lock_sem){++++..}, at: cifsFileInfo_put+0x88f/0x16a0

 but task is already holding lock:
  (&sb->s_type->i_mutex_key#11){+.+.+.}, at: utimes_common+0x3ad/0x870

 which lock already depends on the new lock.

 the existing dependency chain (in reverse order) is:

 -> #1 (&sb->s_type->i_mutex_key#11){+.+.+.}:
        __lock_acquire+0x1f74/0x38f0
        lock_acquire+0x1cc/0x600
        down_write+0x74/0x110
        cifs_strict_writev+0x3cb/0x8c0
        __vfs_write+0x4c1/0x930
        vfs_write+0x14c/0x2d0
        SyS_write+0xf7/0x240
        entry_SYSCALL_64_fastpath+0x1f/0xbe

 -> #0 (&cifsi->lock_sem){++++..}:
        check_prevs_add+0xfa0/0x1d10
        __lock_acquire+0x1f74/0x38f0
        lock_acquire+0x1cc/0x600
        down_write+0x74/0x110
        cifsFileInfo_put+0x88f/0x16a0
        cifs_setattr+0x992/0x1680
        notify_change+0x61a/0xa80
        utimes_common+0x3d4/0x870
        do_utimes+0x1c1/0x220
        SyS_utimensat+0x84/0x1a0
        entry_SYSCALL_64_fastpath+0x1f/0xbe

 other info that might help us debug this:

  Possible unsafe locking scenario:

        CPU0                    CPU1
        ----                    ----
   lock(&sb->s_type->i_mutex_key#11);
                                lock(&cifsi->lock_sem);
                                lock(&sb->s_type->i_mutex_key#11);
   lock(&cifsi->lock_sem);

  *** DEADLOCK ***

 2 locks held by touch/487:
  #0:  (sb_writers#10){.+.+.+}, at: mnt_want_write+0x41/0xb0
  #1:  (&sb->s_type->i_mutex_key#11){+.+.+.}, at: utimes_common+0x3ad/0x870

 stack backtrace:
 CPU: 0 PID: 487 Comm: touch Not tainted 4.12.0-rc7+ #9
 Call Trace:
  dump_stack+0xdb/0x185
  print_circular_bug+0x45b/0x790
  __lock_acquire+0x1f74/0x38f0
  lock_acquire+0x1cc/0x600
  down_write+0x74/0x110
  cifsFileInfo_put+0x88f/0x16a0
  cifs_setattr+0x992/0x1680
  notify_change+0x61a/0xa80
  utimes_common+0x3d4/0x870
  do_utimes+0x1c1/0x220
  SyS_utimensat+0x84/0x1a0
  entry_SYSCALL_64_fastpath+0x1f/0xbe

Fixes: 19dfc1f5f2 ("cifs: fix the race in cifs_writev()")
Signed-off-by: Rabin Vincent <rabinv@axis.com>
Signed-off-by: Steve French <smfrench@gmail.com>
Acked-by: Pavel Shilovsky <pshilov@microsoft.com>
2017-07-05 20:08:39 -05:00
Jeff Layton
97b37f2416 cifs: set mapping error when page writeback fails in writepage or launder_pages
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Steve French <smfrench@gmail.com>
2017-07-05 19:51:04 -05:00
Dan Carpenter
8a7b0d8e8d CIFS: Set ->should_dirty in cifs_user_readv()
The current code causes a static checker warning because ITER_IOVEC is
zero so the condition is never true.

Fixes: 6685c5e2d1 ("CIFS: Add asynchronous read support through kernel AIO")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Steve French <smfrench@gmail.com>
2017-06-20 17:57:27 -05:00
Rabin Vincent
560d388950 CIFS: silence lockdep splat in cifs_relock_file()
cifs_relock_file() can perform a down_write() on the inode's lock_sem even
though it was already performed in cifs_strict_readv().  Lockdep complains
about this.  AFAICS, there is no problem here, and lockdep just needs to be
told that this nesting is OK.

 =============================================
 [ INFO: possible recursive locking detected ]
 4.11.0+ #20 Not tainted
 ---------------------------------------------
 cat/701 is trying to acquire lock:
  (&cifsi->lock_sem){++++.+}, at: cifs_reopen_file+0x7a7/0xc00

 but task is already holding lock:
  (&cifsi->lock_sem){++++.+}, at: cifs_strict_readv+0x177/0x310

 other info that might help us debug this:
  Possible unsafe locking scenario:

        CPU0
        ----
   lock(&cifsi->lock_sem);
   lock(&cifsi->lock_sem);

  *** DEADLOCK ***

  May be due to missing lock nesting notation

 1 lock held by cat/701:
  #0:  (&cifsi->lock_sem){++++.+}, at: cifs_strict_readv+0x177/0x310

 stack backtrace:
 CPU: 0 PID: 701 Comm: cat Not tainted 4.11.0+ #20
 Call Trace:
  dump_stack+0x85/0xc2
  __lock_acquire+0x17dd/0x2260
  ? trace_hardirqs_on_thunk+0x1a/0x1c
  ? preempt_schedule_irq+0x6b/0x80
  lock_acquire+0xcc/0x260
  ? lock_acquire+0xcc/0x260
  ? cifs_reopen_file+0x7a7/0xc00
  down_read+0x2d/0x70
  ? cifs_reopen_file+0x7a7/0xc00
  cifs_reopen_file+0x7a7/0xc00
  ? printk+0x43/0x4b
  cifs_readpage_worker+0x327/0x8a0
  cifs_readpage+0x8c/0x2a0
  generic_file_read_iter+0x692/0xd00
  cifs_strict_readv+0x29f/0x310
  generic_file_splice_read+0x11c/0x1c0
  do_splice_to+0xa5/0xc0
  splice_direct_to_actor+0xfa/0x350
  ? generic_pipe_buf_nosteal+0x10/0x10
  do_splice_direct+0xb5/0xe0
  do_sendfile+0x278/0x3a0
  SyS_sendfile64+0xc4/0xe0
  entry_SYSCALL_64_fastpath+0x1f/0xbe

Signed-off-by: Rabin Vincent <rabinv@axis.com>
Acked-by: Pavel Shilovsky <pshilov@microsoft.com>
Signed-off-by: Steve French <smfrench@gmail.com>
2017-05-09 20:36:02 -05:00
Pavel Shilovsky
c610c4b619 CIFS: Add asynchronous write support through kernel AIO
This patch adds support to process write calls passed by io_submit()
asynchronously. It based on the previously introduced async context
that allows to process i/o responses in a separate thread and
return the caller immediately for asynchronous calls.

This improves writing performance of single threaded applications
with increasing of i/o queue depth size.

Signed-off-by: Pavel Shilovsky <pshilov@microsoft.com>
Signed-off-by: Steve French <smfrench@gmail.com>
2017-05-02 14:57:34 -05:00
Pavel Shilovsky
6685c5e2d1 CIFS: Add asynchronous read support through kernel AIO
This patch adds support to process read calls passed by io_submit()
asynchronously. It based on the previously introduced async context
that allows to process i/o responses in a separate thread and
return the caller immediately for asynchronous calls.

This improves reading performance of single threaded applications
with increasing of i/o queue depth size.

Signed-off-by: Pavel Shilovsky <pshilov@microsoft.com>
Signed-off-by: Steve French <smfrench@gmail.com>
2017-05-02 14:57:34 -05:00
Germano Percossi
1fa839b498 CIFS: store results of cifs_reopen_file to avoid infinite wait
This fixes Continuous Availability when errors during
file reopen are encountered.

cifs_user_readv and cifs_user_writev would wait for ever if
results of cifs_reopen_file are not stored and for later inspection.

In fact, results are checked and, in case of errors, a chain
of function calls leading to reads and writes to be scheduled in
a separate thread is skipped.
These threads will wake up the corresponding waiters once reads
and writes are done.

However, given the return value is not stored, when rc is checked
for errors a previous one (always zero) is inspected instead.
This leads to pending reads/writes added to the list, making
cifs_user_readv and cifs_user_writev wait for ever.

Signed-off-by: Germano Percossi <germano.percossi@citrix.com>
Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>
CC: Stable <stable@vger.kernel.org>
Signed-off-by: Steve French <smfrench@gmail.com>
2017-04-10 23:36:39 -05:00
Dave Jiang
11bac80004 mm, fs: reduce fault, page_mkwrite, and pfn_mkwrite to take only vmf
->fault(), ->page_mkwrite(), and ->pfn_mkwrite() calls do not need to
take a vma and vmf parameter when the vma already resides in vmf.

Remove the vma parameter to simplify things.

[arnd@arndb.de: fix ARM build]
  Link: http://lkml.kernel.org/r/20170125223558.1451224-1-arnd@arndb.de
Link: http://lkml.kernel.org/r/148521301778.19116.10840599906674778980.stgit@djiang5-desk3.ch.intel.com
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Darrick J. Wong <darrick.wong@oracle.com>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Jan Kara <jack@suse.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-02-24 17:46:54 -08:00
Pavel Shilovsky
d70b9104b1 CIFS: Add copy into pages callback for a read operation
Since we have two different types of reads (pagecache and direct)
we need to process such responses differently after decryption of
a packet. The change allows to specify a callback that copies a read
payload data into preallocated pages.

Signed-off-by: Pavel Shilovsky <pshilov@microsoft.com>
2017-02-01 16:46:36 -06:00
Pavel Shilovsky
9c25702cee CIFS: Fix splice read for non-cached files
Currently we call copy_page_to_iter() for uncached reading into a pipe.
This is wrong because it treats pages as VFS cache pages and copies references
rather than actual data. When we are trying to read from the pipe we end up
calling page_cache_pipe_buf_confirm() which returns -ENODATA. This error
is translated into 0 which is returned to a user.

This issue is reproduced by running xfs-tests suite (generic test #249)
against mount points with "cache=none". Fix it by mapping pages manually
and calling copy_to_iter() that copies data into the pipe.

Cc: Stable <stable@vger.kernel.org>
Signed-off-by: Pavel Shilovsky <pshilov@microsoft.com>
2017-02-01 16:46:34 -06:00
Pavel Shilovsky
96a988ffeb CIFS: Fix a possible double locking of mutex during reconnect
With the current code it is possible to lock a mutex twice when
a subsequent reconnects are triggered. On the 1st reconnect we
reconnect sessions and tcons and then persistent file handles.
If the 2nd reconnect happens during the reconnecting of persistent
file handles then the following sequence of calls is observed:

cifs_reopen_file -> SMB2_open -> small_smb2_init -> smb2_reconnect
-> cifs_reopen_persistent_file_handles -> cifs_reopen_file (again!).

So, we are trying to acquire the same cfile->fh_mutex twice which
is wrong. Fix this by moving reconnecting of persistent handles to
the delayed work (smb2_reconnect_server) and submitting this work
every time we reconnect tcon in SMB2 commands handling codepath.

This can also lead to corruption of a temporary file list in
cifs_reopen_persistent_file_handles() because we can recursively
call this function twice.

Cc: Stable <stable@vger.kernel.org> # v4.9+
Signed-off-by: Pavel Shilovsky <pshilov@microsoft.com>
2016-12-05 12:52:01 -08:00
Pavel Shilovsky
de74025052 CIFS: Reset read oplock to NONE if we have mandatory locks after reopen
We are already doing the same thing for an ordinary open case:
we can't keep read oplock on a file if we have mandatory byte-range
locks because pagereading can conflict with these locks on a server.
Fix it by setting oplock level to NONE.

Signed-off-by: Pavel Shilovsky <pshilov@microsoft.com>
Signed-off-by: Steve French <smfrench@gmail.com>
2016-10-13 19:48:59 -05:00
Pavel Shilovsky
f2cca6a7c9 CIFS: Fix persistent handles re-opening on reconnect
openFileList of tcon can be changed while cifs_reopen_file() is called
that can lead to an unexpected behavior when we return to the loop.
Fix this by introducing a temp list for keeping all file handles that
need to be reopen.

Signed-off-by: Pavel Shilovsky <pshilov@microsoft.com>
Signed-off-by: Steve French <smfrench@gmail.com>
2016-10-13 19:48:55 -05:00
Steve French
52ace1ef12 fs/cifs: reopen persistent handles on reconnect
Continuous Availability features like persistent handles
require that clients reconnect their open files, not
just the sessions, soon after the network connection comes
back up, otherwise the server will throw away the state
(byte range locks, leases, deny modes) on those handles
after a timeout.

Add code to reconnect handles when use_persistent set
(e.g. Continuous Availability shares) after tree reconnect.

Signed-off-by: Aurelien Aptel <aaptel@suse.com>
Reviewed-by: Germano Percossi <germano.percossi@citrix.com>
Signed-off-by: Steve French <smfrench@gmail.com>
2016-10-12 12:08:33 -05:00
Steve French
3afca265b5 Clarify locking of cifs file and tcon structures and make more granular
Remove the global file_list_lock to simplify cifs/smb3 locking and
have spinlocks that more closely match the information they are
protecting.

Add new tcon->open_file_lock and file->file_info_lock spinlocks.
Locks continue to follow a heirachy,
	cifs_socket --> cifs_ses --> cifs_tcon --> cifs_file
where global tcp_ses_lock still protects socket and cifs_ses, while the
the newer locks protect the lower level structure's information
(tcon and cifs_file respectively).

CC: Stable <stable@vger.kernel.org>
Signed-off-by: Steve French <steve.french@primarydata.com>
Signed-off-by: Pavel Shilovsky <pshilov@microsoft.com>
Reviewed-by: Aurelien Aptel <aaptel@suse.com>
Reviewed-by: Germano Percossi <germano.percossi@citrix.com>
2016-10-12 12:08:32 -05:00
Linus Torvalds
101105b171 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull more vfs updates from Al Viro:
 ">rename2() work from Miklos + current_time() from Deepa"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  fs: Replace current_fs_time() with current_time()
  fs: Replace CURRENT_TIME_SEC with current_time() for inode timestamps
  fs: Replace CURRENT_TIME with current_time() for inode timestamps
  fs: proc: Delete inode time initializations in proc_alloc_inode()
  vfs: Add current_time() api
  vfs: add note about i_op->rename changes to porting
  fs: rename "rename2" i_op to "rename"
  vfs: remove unused i_op->rename
  fs: make remaining filesystems use .rename2
  libfs: support RENAME_NOREPLACE in simple_rename()
  fs: support RENAME_NOREPLACE for local filesystems
  ncpfs: fix unused variable warning
2016-10-10 20:16:43 -07:00
Deepa Dinamani
c2050a454c fs: Replace current_fs_time() with current_time()
current_fs_time() uses struct super_block* as an argument.
As per Linus's suggestion, this is changed to take struct
inode* as a parameter instead. This is because the function
is primarily meant for vfs inode timestamps.
Also the function was renamed as per Arnd's suggestion.

Change all calls to current_fs_time() to use the new
current_time() function instead. current_fs_time() will be
deleted.

Signed-off-by: Deepa Dinamani <deepa.kernel@gmail.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-09-27 21:06:22 -04:00
Al Viro
fc56b9838a cifs: don't use memcpy() to copy struct iov_iter
it's not 70s anymore.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-09-27 18:13:04 -04:00
Michal Hocko
8a5c743e30 mm, memcg: use consistent gfp flags during readahead
Vladimir has noticed that we might declare memcg oom even during
readahead because read_pages only uses GFP_KERNEL (with mapping_gfp
restriction) while __do_page_cache_readahead uses
page_cache_alloc_readahead which adds __GFP_NORETRY to prevent from
OOMs.  This gfp mask discrepancy is really unfortunate and easily
fixable.  Drop page_cache_alloc_readahead() which only has one user and
outsource the gfp_mask logic into readahead_gfp_mask and propagate this
mask from __do_page_cache_readahead down to read_pages.

This alone would have only very limited impact as most filesystems are
implementing ->readpages and the common implementation mpage_readpages
does GFP_KERNEL (with mapping_gfp restriction) again.  We can tell it to
use readahead_gfp_mask instead as this function is called only during
readahead as well.  The same applies to read_cache_pages.

ext4 has its own ext4_mpage_readpages but the path which has pages !=
NULL can use the same gfp mask.  Btrfs, cifs, f2fs and orangefs are
doing a very similar pattern to mpage_readpages so the same can be
applied to them as well.

[akpm@linux-foundation.org: coding-style fixes]
[mhocko@suse.com: restrict gfp mask in mpage_alloc]
  Link: http://lkml.kernel.org/r/20160610074223.GC32285@dhcp22.suse.cz
Link: http://lkml.kernel.org/r/1465301556-26431-1-git-send-email-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Cc: Vladimir Davydov <vdavydov@parallels.com>
Cc: Chris Mason <clm@fb.com>
Cc: Steve French <sfrench@samba.org>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Jan Kara <jack@suse.cz>
Cc: Mike Marshall <hubcap@omnibond.com>
Cc: Jaegeuk Kim <jaegeuk@kernel.org>
Cc: Changman Lee <cm224.lee@samsung.com>
Cc: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-07-26 16:19:19 -07:00
Jeff Layton
3d22462ae9 cifs: stuff the fl_owner into "pid" field in the lock request
Right now, we send the tgid cross the wire. What we really want to send
though is a hashed fl_owner_t since samba treats this field as a generic
lockowner.

It turns out that because we enforce and release locks locally before
they are ever sent to the server, this patch makes no difference in
behavior. Still, setting OFD locks on the server using the process
pid seems wrong, so I think this patch still makes sense.

Signed-off-by: Jeff Layton <jlayton@poochiereds.net>
Signed-off-by: Steve French <smfrench@gmail.com>
Acked-by: Pavel Shilovsky <pshilovsky@samba.org>
Acked-by: Sachin Prabhu <sprabhu@redhat.com>
2016-06-23 23:44:44 -05:00
Linus Torvalds
442c9ac989 Merge branch 'sendmsg.cifs' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull cifs iovec cleanups from Al Viro.

* 'sendmsg.cifs' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  cifs: don't bother with kmap on read_pages side
  cifs_readv_receive: use cifs_read_from_socket()
  cifs: no need to wank with copying and advancing iovec on recvmsg side either
  cifs: quit playing games with draining iovecs
  cifs: merge the hash calculation helpers
2016-05-18 10:17:56 -07:00
Linus Torvalds
8908c94d6c Merge branch 'for-next' of git://git.samba.org/sfrench/cifs-2.6
Pull cifs updates from Steve French:
 "Various small CIFS and SMB3 fixes (including some for stable)"

* 'for-next' of git://git.samba.org/sfrench/cifs-2.6:
  remove directory incorrectly tries to set delete on close on non-empty directories
  Update cifs.ko version to 2.09
  fs/cifs: correctly to anonymous authentication for the NTLM(v2) authentication
  fs/cifs: correctly to anonymous authentication for the NTLM(v1) authentication
  fs/cifs: correctly to anonymous authentication for the LANMAN authentication
  fs/cifs: correctly to anonymous authentication via NTLMSSP
  cifs: remove any preceding delimiter from prefix_path
  cifs: Use file_dentry()
2016-05-18 10:01:47 -07:00
Goldwyn Rodrigues
1f1735cb75 cifs: Use file_dentry()
CIFS may be used as lower layer of overlayfs and accessing f_path.dentry can
lead to a crash.

Fix by replacing direct access of file->f_path.dentry with the
file_dentry() accessor, which will always return a native object.

Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Acked-by: Shirish Pargaonkar <shirishpargaonkar@gmail.com>
Signed-off-by: Steve French <smfrench@gmail.com>
2016-05-17 14:09:33 -05:00
Christoph Hellwig
e259221763 fs: simplify the generic_write_sync prototype
The kiocb already has the new position, so use that.  The only interesting
case is AIO, where we currently don't bother updating ki_pos.  We're about
to free the kiocb after we're done, so we might as well update it to make
everyone's life simpler.

While we're at it also return the bytes written argument passed in if
we were successful so that the boilerplate error switch code in the
callers can go away.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-05-01 19:58:39 -04:00
Christoph Hellwig
dde0c2e798 fs: add IOCB_SYNC and IOCB_DSYNC
This will allow us to do per-I/O sync file writes, as required by a lot
of fileservers or storage targets.

XXX: Will need a few additional audits for O_DSYNC

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-05-01 19:58:39 -04:00
Christoph Hellwig
c8b8e32d70 direct-io: eliminate the offset argument to ->direct_IO
Including blkdev_direct_IO and dax_do_io.  It has to be ki_pos to actually
work, so eliminate the superflous argument.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-05-01 19:58:39 -04:00
Kirill A. Shutemov
ea1754a084 mm, fs: remove remaining PAGE_CACHE_* and page_cache_{get,release} usage
Mostly direct substitution with occasional adjustment or removing
outdated comments.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-04-04 10:41:08 -07:00
Kirill A. Shutemov
09cbfeaf1a mm, fs: get rid of PAGE_CACHE_* and page_cache_{get,release} macros
PAGE_CACHE_{SIZE,SHIFT,MASK,ALIGN} macros were introduced *long* time
ago with promise that one day it will be possible to implement page
cache with bigger chunks than PAGE_SIZE.

This promise never materialized.  And unlikely will.

We have many places where PAGE_CACHE_SIZE assumed to be equal to
PAGE_SIZE.  And it's constant source of confusion on whether
PAGE_CACHE_* or PAGE_* constant should be used in a particular case,
especially on the border between fs and mm.

Global switching to PAGE_CACHE_SIZE != PAGE_SIZE would cause to much
breakage to be doable.

Let's stop pretending that pages in page cache are special.  They are
not.

The changes are pretty straight-forward:

 - <foo> << (PAGE_CACHE_SHIFT - PAGE_SHIFT) -> <foo>;

 - <foo> >> (PAGE_CACHE_SHIFT - PAGE_SHIFT) -> <foo>;

 - PAGE_CACHE_{SIZE,SHIFT,MASK,ALIGN} -> PAGE_{SIZE,SHIFT,MASK,ALIGN};

 - page_cache_get() -> get_page();

 - page_cache_release() -> put_page();

This patch contains automated changes generated with coccinelle using
script below.  For some reason, coccinelle doesn't patch header files.
I've called spatch for them manually.

The only adjustment after coccinelle is revert of changes to
PAGE_CAHCE_ALIGN definition: we are going to drop it later.

There are few places in the code where coccinelle didn't reach.  I'll
fix them manually in a separate patch.  Comments and documentation also
will be addressed with the separate patch.

virtual patch

@@
expression E;
@@
- E << (PAGE_CACHE_SHIFT - PAGE_SHIFT)
+ E

@@
expression E;
@@
- E >> (PAGE_CACHE_SHIFT - PAGE_SHIFT)
+ E

@@
@@
- PAGE_CACHE_SHIFT
+ PAGE_SHIFT

@@
@@
- PAGE_CACHE_SIZE
+ PAGE_SIZE

@@
@@
- PAGE_CACHE_MASK
+ PAGE_MASK

@@
expression E;
@@
- PAGE_CACHE_ALIGN(E)
+ PAGE_ALIGN(E)

@@
expression E;
@@
- page_cache_get(E)
+ get_page(E)

@@
expression E;
@@
- page_cache_release(E)
+ put_page(E)

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-04-04 10:41:08 -07:00
Al Viro
71335664c3 cifs: don't bother with kmap on read_pages side
just do ITER_BVEC recvmsg

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-03-28 14:05:52 -04:00
Al Viro
5955102c99 wrappers for ->i_mutex access
parallel to mutex_{lock,unlock,trylock,is_locked,lock_nested},
inode_foo(inode) being mutex_foo(&inode->i_mutex).

Please, use those for access to ->i_mutex; over the coming cycle
->i_mutex will become rwsem, with ->lookup() done with it held
only shared.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-01-22 18:04:28 -05:00