If a SIGKILL is sent to a task waiting in __nfs_iocounter_wait,
it will busy-wait or soft lockup in its while loop.
nfs_wait_bit_killable won't sleep, and the loop won't exit on
the error return.
Stop the busy-wait by breaking out of the loop when
nfs_wait_bit_killable returns an error.
Signed-off-by: David Jeffery <djeffery@redhat.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Commit 6094f83864
"nfs: allow coalescing of subpage requests" got rid of the requirement
that requests cover whole pages, but it made some incorrect assumptions.
It turns out that callers of this interface can map adjacent requests
(by file position as seen by req_offset + req->wb_bytes) to different pages,
even when they could share a page. An example is the direct I/O interface -
iov_iter_get_pages_alloc may return one segment with a partial page filled
and the next segment (which is adjacent in the file position) starts with a
new page.
Reported-by: Toralf Förster <toralf.foerster@gmx.de>
Signed-off-by: Weston Andros Adamson <dros@primarydata.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Adjacent requests that share the same page are allowed, but should only
use one entry in the page vector. This avoids overruning the page
vector - it is sized based on how many bytes there are, not by
request count.
This fixes issues that manifest as "Redzone overwritten" bugs (the
vector overrun) and hangs waiting on page read / write, as it waits on
the same page more than once.
This also adds bounds checking to the page vector with a graceful failure
(WARN_ON_ONCE and pgio error returned to application).
Reported-by: Toralf Förster <toralf.foerster@gmx.de>
Signed-off-by: Weston Andros Adamson <dros@primarydata.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
This handles the 'nonblock=false' case in nfs_lock_and_join_requests.
If the group is already locked and blocking is allowed, drop the inode lock
and wait for the group lock to be cleared before trying it all again.
This should fix warnings found in peterz's tree (sched/wait branch), where
might_sleep() checks are added to wait.[ch].
Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Weston Andros Adamson <dros@primarydata.com>
Reviewed-by: Peng Tao <tao.peng@primarydata.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
This fixes handling of errors from nfs_page_group_lock in
nfs_lock_and_join_requests. It now releases the inode lock and the
reference to the head request.
Reported-by: Peng Tao <tao.peng@primarydata.com>
Signed-off-by: Weston Andros Adamson <dros@primarydata.com>
Reviewed-by: Peng Tao <tao.peng@primarydata.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
__nfs_pageio_add_request was calling nfs_page_group_lock nonblocking, but
this can return -EAGAIN which would end up passing -EIO to the application.
There is no reason not to block in this path, so change the two calls to
do so. Also, there is no need to check the return value of
nfs_page_group_lock when nonblock=false, so remove the error handling code.
Signed-off-by: Weston Andros Adamson <dros@primarydata.com>
Reviewed-by: Peng Tao <tao.peng@primarydata.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
nfs_page_group_lock was calling wait_on_bit_lock even when told not to
block. Fix by first trying test_and_set_bit, followed by wait_on_bit_lock
if and only if blocking is allowed. Return -EAGAIN if nonblocking and the
test_and_set of the bit was already locked.
Signed-off-by: Weston Andros Adamson <dros@primarydata.com>
Reviewed-by: Peng Tao <tao.peng@primarydata.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Flip the meaning of the second argument from 'wait' to 'nonblock' to
match related functions. Update all five calls to reflect this change.
Signed-off-by: Weston Andros Adamson <dros@primarydata.com>
Reviewed-by: Peng Tao <tao.peng@primarydata.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Highlights include:
- Stable fix for a bug in nfs3_list_one_acl()
- Speed up NFS path walks by supporting LOOKUP_RCU
- More read/write code cleanups
- pNFS fixes for layout return on close
- Fixes for the RCU handling in the rpcsec_gss code
- More NFS/RDMA fixes
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Merge tag 'nfs-for-3.17-1' of git://git.linux-nfs.org/projects/trondmy/linux-nfs
Pull NFS client updates from Trond Myklebust:
"Highlights include:
- stable fix for a bug in nfs3_list_one_acl()
- speed up NFS path walks by supporting LOOKUP_RCU
- more read/write code cleanups
- pNFS fixes for layout return on close
- fixes for the RCU handling in the rpcsec_gss code
- more NFS/RDMA fixes"
* tag 'nfs-for-3.17-1' of git://git.linux-nfs.org/projects/trondmy/linux-nfs: (79 commits)
nfs: reject changes to resvport and sharecache during remount
NFS: Avoid infinite loop when RELEASE_LOCKOWNER getting expired error
SUNRPC: remove all refcounting of groupinfo from rpcauth_lookupcred
NFS: fix two problems in lookup_revalidate in RCU-walk
NFS: allow lockless access to access_cache
NFS: teach nfs_lookup_verify_inode to handle LOOKUP_RCU
NFS: teach nfs_neg_need_reval to understand LOOKUP_RCU
NFS: support RCU_WALK in nfs_permission()
sunrpc/auth: allow lockless (rcu) lookup of credential cache.
NFS: prepare for RCU-walk support but pushing tests later in code.
NFS: nfs4_lookup_revalidate: only evaluate parent if it will be used.
NFS: add checks for returned value of try_module_get()
nfs: clear_request_commit while holding i_lock
pnfs: add pnfs_put_lseg_async
pnfs: find swapped pages on pnfs commit lists too
nfs: fix comment and add warn_on for PG_INODE_REF
nfs: check wait_on_bit_lock err in page_group_lock
sunrpc: remove "ec" argument from encrypt_v2 operation
sunrpc: clean up sparse endianness warnings in gss_krb5_wrap.c
sunrpc: clean up sparse endianness warnings in gss_krb5_seal.c
...
Pull vfs updates from Al Viro:
"Stuff in here:
- acct.c fixes and general rework of mnt_pin mechanism. That allows
to go for delayed-mntput stuff, which will permit mntput() on deep
stack without worrying about stack overflows - fs shutdown will
happen on shallow stack. IOW, we can do Eric's umount-on-rmdir
series without introducing tons of stack overflows on new mntput()
call chains it introduces.
- Bruce's d_splice_alias() patches
- more Miklos' rename() stuff.
- a couple of regression fixes (stable fodder, in the end of branch)
and a fix for API idiocy in iov_iter.c.
There definitely will be another pile, maybe even two. I'd like to
get Eric's series in this time, but even if we miss it, it'll go right
in the beginning of for-next in the next cycle - the tricky part of
prereqs is in this pile"
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (40 commits)
fix copy_tree() regression
__generic_file_write_iter(): fix handling of sync error after DIO
switch iov_iter_get_pages() to passing maximal number of pages
fs: mark __d_obtain_alias static
dcache: d_splice_alias should detect loops
exportfs: update Exporting documentation
dcache: d_find_alias needn't recheck IS_ROOT && DCACHE_DISCONNECTED
dcache: remove unused d_find_alias parameter
dcache: d_obtain_alias callers don't all want DISCONNECTED
dcache: d_splice_alias should ignore DCACHE_DISCONNECTED
dcache: d_splice_alias mustn't create directory aliases
dcache: close d_move race in d_splice_alias
dcache: move d_splice_alias
namei: trivial fix to vfs_rename_dir comment
VFS: allow ->d_manage() to declare -EISDIR in rcu_walk mode.
cifs: support RENAME_NOREPLACE
hostfs: support rename flags
shmem: support RENAME_EXCHANGE
shmem: support RENAME_NOREPLACE
btrfs: add RENAME_NOREPLACE
...
Pull namespace updates from Eric Biederman:
"This is a bunch of small changes built against 3.16-rc6. The most
significant change for users is the first patch which makes setns
drmatically faster by removing unneded rcu handling.
The next chunk of changes are so that "mount -o remount,.." will not
allow the user namespace root to drop flags on a mount set by the
system wide root. Aks this forces read-only mounts to stay read-only,
no-dev mounts to stay no-dev, no-suid mounts to stay no-suid, no-exec
mounts to stay no exec and it prevents unprivileged users from messing
with a mounts atime settings. I have included my test case as the
last patch in this series so people performing backports can verify
this change works correctly.
The next change fixes a bug in NFS that was discovered while auditing
nsproxy users for the first optimization. Today you can oops the
kernel by reading /proc/fs/nfsfs/{servers,volumes} if you are clever
with pid namespaces. I rebased and fixed the build of the
!CONFIG_NFS_FS case yesterday when a build bot caught my typo. Given
that no one to my knowledge bases anything on my tree fixing the typo
in place seems more responsible that requiring a typo-fix to be
backported as well.
The last change is a small semantic cleanup introducing
/proc/thread-self and pointing /proc/mounts and /proc/net at it. This
prevents several kinds of problemantic corner cases. It is a
user-visible change so it has a minute chance of causing regressions
so the change to /proc/mounts and /proc/net are individual one line
commits that can be trivially reverted. Unfortunately I lost and
could not find the email of the original reporter so he is not
credited. From at least one perspective this change to /proc/net is a
refgression fix to allow pthread /proc/net uses that were broken by
the introduction of the network namespace"
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace:
proc: Point /proc/mounts at /proc/thread-self/mounts instead of /proc/self/mounts
proc: Point /proc/net at /proc/thread-self/net instead of /proc/self/net
proc: Implement /proc/thread-self to point at the directory of the current thread
proc: Have net show up under /proc/<tgid>/task/<tid>
NFS: Fix /proc/fs/nfsfs/servers and /proc/fs/nfsfs/volumes
mnt: Add tests for unprivileged remount cases that have found to be faulty
mnt: Change the default remount atime from relatime to the existing value
mnt: Correct permission checks in do_remount
mnt: Move the test for MNT_LOCK_READONLY from change_mount_flags into do_remount
mnt: Only change user settable mount flags in remount
namespaces: Use task_lock and not rcu to protect nsproxy
There are a few d_obtain_alias callers that are using it to get the
root of a filesystem which may already have an alias somewhere else.
This is not the same as the filehandle-lookup case, and none of them
actually need DCACHE_DISCONNECTED set.
It isn't really a serious problem, but it would really be clearer if we
reserved DCACHE_DISCONNECTED for those cases where it's actually needed.
In the btrfs case this was causing a spurious printk from
nfsd/nfsfh.c:fh_verify when it found an unexpected DCACHE_DISCONNECTED
dentry. Josef worked around this by unsetting DCACHE_DISCONNECTED
manually in 3a0dfa6a12 "Btrfs: unset DCACHE_DISCONNECTED when mounting
default subvol", and this replaces that workaround.
Cc: Josef Bacik <jbacik@fb.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Pull security subsystem updates from James Morris:
"In this release:
- PKCS#7 parser for the key management subsystem from David Howells
- appoint Kees Cook as seccomp maintainer
- bugfixes and general maintenance across the subsystem"
* 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security: (94 commits)
X.509: Need to export x509_request_asymmetric_key()
netlabel: shorter names for the NetLabel catmap funcs/structs
netlabel: fix the catmap walking functions
netlabel: fix the horribly broken catmap functions
netlabel: fix a problem when setting bits below the previously lowest bit
PKCS#7: X.509 certificate issuer and subject are mandatory fields in the ASN.1
tpm: simplify code by using %*phN specifier
tpm: Provide a generic means to override the chip returned timeouts
tpm: missing tpm_chip_put in tpm_get_random()
tpm: Properly clean sysfs entries in error path
tpm: Add missing tpm_do_selftest to ST33 I2C driver
PKCS#7: Use x509_request_asymmetric_key()
Revert "selinux: fix the default socket labeling in sock_graft()"
X.509: x509_request_asymmetric_keys() doesn't need string length arguments
PKCS#7: fix sparse non static symbol warning
KEYS: revert encrypted key change
ima: add support for measuring and appraising firmware
firmware_class: perform new LSM checks
security: introduce kernel_fw_from_file hook
PKCS#7: Missing inclusion of linux/err.h
...
Commit c8e47028 made it possible to change resvport/noresvport and
sharecache/nosharecache via a remount operation, neither of which should be
allowed.
Signed-off-by: Scott Mayhew <smayhew@redhat.com>
Fixes: c8e47028 (nfs: Apply NFS_MOUNT_CMP_FLAGMASK to nfs_compare_remount_data)
Cc: stable@vger.kernel.org # 3.16+
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
The usage of pid_ns->child_reaper->nsproxy->net_ns in
nfs_server_list_open and nfs_client_list_open is not safe.
/proc for a pid namespace can remain mounted after the all of the
process in that pid namespace have exited. There are also times
before the initial process in a pid namespace has started or after the
initial process in a pid namespace has exited where
pid_ns->child_reaper can be NULL or stale. Making the idiom
pid_ns->child_reaper->nsproxy a double whammy of problems.
Luckily all that needs to happen is to move /proc/fs/nfsfs/servers and
/proc/fs/nfsfs/volumes under /proc/net to /proc/net/nfsfs/servers and
/proc/net/nfsfs/volumes and add a symlink from the original location,
and to use seq_open_net as it has been designed.
Cc: stable@vger.kernel.org
Cc: Trond Myklebust <trond.myklebust@primarydata.com>
Cc: Stanislav Kinsbursky <skinsbursky@parallels.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
1/ rcu_dereference isn't correct: that field isn't
RCU protected. It could potentially change at any time
so ACCESS_ONCE might be justified.
changes to ->d_parent are protected by ->d_seq. However
that isn't always checked after ->d_revalidate is called,
so it is safest to keep the double-check that ->d_parent
hasn't changed at the end of these functions.
2/ in nfs4_lookup_revalidate, "->d_parent" was forgotten.
So 'parent' was not the parent of 'dentry'.
This fails safe is the context is that dentry->d_inode is
NULL, and the result of parent->d_inode being NULL is
that ECHILD is returned, which is always safe.
Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
The access cache is used during RCU-walk path lookups, so it is best
to avoid locking if possible as taking a lock kills concurrency.
The rbtree is not rcu-safe and cannot easily be made so.
Instead we simply check the last (i.e. most recent) entry on the LRU
list. If this doesn't match, then we return -ECHILD and retry in
lock/refcount mode.
This requires freeing the nfs_access_entry struct with rcu, and
requires using rcu access primatives when adding entries to the lru, and
when examining the last entry.
Calling put_rpccred before kfree_rcu looks a bit odd, but as
put_rpccred already provides rcu protection, we know that the cred will
not actually be freed until the next grace period, so any concurrent
access will be safe.
This patch provides about 5% performance improvement on a stat-heavy
synthetic work load with 4 threads on a 2-core CPU.
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
It fails with -ECHILD rather than make an RPC call.
This allows nfs_lookup_revalidate to call it in RCU-walk mode.
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
This requires nfs_check_verifier to take an rcu_walk flag, and requires
an rcu version of nfs_revalidate_inode which returns -ECHILD rather
than making an RPC call.
With this, nfs_lookup_revalidate can call nfs_neg_need_reval in
RCU-walk mode.
We can also move the LOOKUP_RCU check past the nfs_check_verifier()
call in nfs_lookup_revalidate.
If RCU_WALK prevents nfs_check_verifier or nfs_neg_need_reval from
doing a full check, they return a status indicating that a revalidation
is required. As this revalidation will not be possible in RCU_WALK
mode, -ECHILD will ultimately be returned, which is the desired result.
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
nfs_permission makes two calls which are not always safe in RCU_WALK,
rpc_lookup_cred and nfs_do_access.
The second can easily be made rcu-safe by aborting with -ECHILD before
making the RPC call.
The former can be made rcu-safe by calling rpc_lookup_cred_nonblock()
instead.
As this will almost always succeed, we use it even when RCU_WALK
isn't being used as it still saves some spinlocks in a common case.
We only fall back to rpc_lookup_cred() if rpc_lookup_cred_nonblock()
fails and MAY_NOT_BLOCK isn't set.
This optimisation (always trying rpc_lookup_cred_nonblock()) is
particularly important when a security module is active.
In that case inode_permission() may return -ECHILD from
security_inode_permission() even though ->permission() succeeded in
RCU_WALK mode.
This leads to may_lookup() retrying inode_permission after performing
unlazy_walk(). The spinlock that rpc_lookup_cred() takes is often
more expensive than anything security_inode_permission() does, so that
spinlock becomes the main bottleneck.
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
nfs_lookup_revalidate, nfs4_lookup_revalidate, and nfs_permission
all need to understand and handle RCU-walk for NFS to gain the
benefits of RCU-walk for cached information.
Currently these functions all immediately return -ECHILD
if the relevant flag (LOOKUP_RCU or MAY_NOT_BLOCK) is set.
This patch pushes those tests later in the code so that we only abort
immediately before we enter rcu-unsafe code. As subsequent patches
make that rcu-unsafe code rcu-safe, several of these new tests will
disappear.
With this patch there are several paths through the code which will no
longer return -ECHILD during an RCU-walk. However these are mostly
error paths or other uninteresting cases.
A noteworthy change in nfs_lookup_revalidate is that we don't take
(or put) the reference to ->d_parent when LOOKUP_RCU is set.
Rather we rcu_dereference ->d_parent, and check that ->d_inode
is not NULL. We also check that ->d_parent hasn't changed after
all the tests.
In nfs4_lookup_revalidate we simply avoid testing LOOKUP_RCU on the
path that only calls nfs_lookup_revalidate() as that function
already performs the required test.
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
nfs4_lookup_revalidate only uses 'parent' to get 'dir', and only
uses 'dir' if 'inode == NULL'.
So we don't need to find out what 'parent' or 'dir' is until we
know that 'inode' is NULL.
By moving 'dget_parent' inside the 'if', we can reduce the number of
call sites for 'dput(parent)'.
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
There is a couple of places in client code where returned value
of try_module_get() is ignored. As a result there is a small chance
to premature unload module because of unbalanced refcounting.
The patch adds error handling in that places.
Found by Linux Driver Verification project (linuxtesting.org).
Signed-off-by: Alexey Khoroshilov <khoroshilov@ispras.ru>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
This is useful when lsegs need to be released while holding locks.
Signed-off-by: Weston Andros Adamson <dros@primarydata.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
nfs_page_find_head_request_locked looks through the regular nfs commit lists
when the page is swapped out, but doesn't look through the pnfs commit lists.
I'm not sure if anyone has hit any issues caused by this.
Suggested-by: Peng Tao <tao.peng@primarydata.com>
Signed-off-by: Weston Andros Adamson <dros@primarydata.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Fix the comment in nfs_page.h for PG_INODE_REF to reflect that it's no longer
set only on head requests. Also add a WARN_ON_ONCE in nfs_inode_remove_request
as PG_INODE_REF should always be set.
Suggested-by: Peng Tao <tao.peng@primarydata.com>
Signed-off-by: Weston Andros Adamson <dros@primarydata.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Return errors from wait_on_bit_lock from nfs_page_group_lock.
Add a bool argument @wait to nfs_page_group_lock. If true, loop over
wait_on_bit_lock until it returns cleanly. If false, return the error
from wait_on_bit_lock.
Signed-off-by: Weston Andros Adamson <dros@primarydata.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
If you have an NFSv4 mounted directory which does not container 'foo'
and:
ls -l foo
ssh $server touch foo
cat foo
then the 'cat' will fail (usually, depending a bit on the various
cache ages). This is correct as negative looks are cached by default.
However with the same initial conditions:
cat foo
ssh $server touch foo
cat foo
will usually succeed. This is because an "open" does not add a
negative dentry to the dcache, while a "lookup" does.
This can have negative performance effects. When "gcc" searches for
an include file, it will try to "open" the file in every director in
the search path. Without caching of negative "open" results, this
generates much more traffic to the server than it should (or than
NFSv3 does).
The root of the problem is that _nfs4_open_and_get_state() will call
d_add_unique() on a positive result, but not on a negative result.
Compare with nfs_lookup() which calls d_materialise_unique on both
a positive result and on ENOENT.
This patch adds a call d_add() in the ENOENT case for
_nfs4_open_and_get_state() and also calls nfs_set_verifier().
With it, many fewer "open" requests for known-non-existent files are
sent to the server.
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
There was a check for result being not NULL. But get_acl() may return
NULL, or ERR_PTR, or actual pointer.
The purpose of the function where current change is done is to "list
ACLs only when they are available", so any error condition of get_acl()
mustn't be elevated, and returning 0 there is still valid.
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=81111
Signed-off-by: Andrey Utkin <andrey.krieger.utkin@gmail.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Fixes: 74adf83f5d (nfs: only show Posix ACLs in listxattr if actually...)
Cc: stable@vger.kernel.org # 3.14+
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
This may be used to limit the number of cached credentials building up
inside the access cache.
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Make use of key preparsing in user-defined and logon keys so that quota size
determination can take place prior to keyring locking when a key is being
added.
Also the idmapper key types need to change to match as they use the
user-defined key type routines.
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Steve Dickson <steved@redhat.com>
Acked-by: Jeff Layton <jlayton@primarydata.com>
Special kernel keys, such as those used to hold DNS results for AFS, CIFS and
NFS and those used to hold idmapper results for NFS, used to be
'invalidateable' with key_revoke(). However, since the default permissions for
keys were reduced:
Commit: 96b5c8fea6
KEYS: Reduce initial permissions on keys
it has become impossible to do this.
Add a key flag (KEY_FLAG_ROOT_CAN_INVAL) that will permit a key to be
invalidated by root. This should not be used for system keyrings as the
garbage collector will try and remove any invalidate key. For system keyrings,
KEY_FLAG_ROOT_CAN_CLEAR can be used instead.
After this, from userspace, keyctl_invalidate() and "keyctl invalidate" can be
used by any possessor of CAP_SYS_ADMIN (typically root) to invalidate DNS and
idmapper keys. Invalidated keys are immediately garbage collected and will be
immediately rerequested if needed again.
Signed-off-by: David Howells <dhowells@redhat.com>
Tested-by: Steve Dickson <steved@redhat.com>
It is currently not possible for various wait_on_bit functions
to implement a timeout.
While the "action" function that is called to do the waiting
could certainly use schedule_timeout(), there is no way to carry
forward the remaining timeout after a false wake-up.
As false-wakeups a clearly possible at least due to possible
hash collisions in bit_waitqueue(), this is a real problem.
The 'action' function is currently passed a pointer to the word
containing the bit being waited on. No current action functions
use this pointer. So changing it to something else will be a
little noisy but will have no immediate effect.
This patch changes the 'action' function to take a pointer to
the "struct wait_bit_key", which contains a pointer to the word
containing the bit so nothing is really lost.
It also adds a 'private' field to "struct wait_bit_key", which
is initialized to zero.
An action function can now implement a timeout with something
like
static int timed_out_waiter(struct wait_bit_key *key)
{
unsigned long waited;
if (key->private == 0) {
key->private = jiffies;
if (key->private == 0)
key->private -= 1;
}
waited = jiffies - key->private;
if (waited > 10 * HZ)
return -EAGAIN;
schedule_timeout(waited - 10 * HZ);
return 0;
}
If any other need for context in a waiter were found it would be
easy to use ->private for some other purpose, or even extend
"struct wait_bit_key".
My particular need is to support timeouts in nfs_release_page()
to avoid deadlocks with loopback mounted NFS.
While wait_on_bit_timeout() would be a cleaner interface, it
will not meet my need. I need the timeout to be sensitive to
the state of the connection with the server, which could change.
So I need to use an 'action' interface.
Signed-off-by: NeilBrown <neilb@suse.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Steve French <sfrench@samba.org>
Cc: David Howells <dhowells@redhat.com>
Cc: Steven Whitehouse <swhiteho@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/20140707051604.28027.41257.stgit@notabene.brown
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The current "wait_on_bit" interface requires an 'action'
function to be provided which does the actual waiting.
There are over 20 such functions, many of them identical.
Most cases can be satisfied by one of just two functions, one
which uses io_schedule() and one which just uses schedule().
So:
Rename wait_on_bit and wait_on_bit_lock to
wait_on_bit_action and wait_on_bit_lock_action
to make it explicit that they need an action function.
Introduce new wait_on_bit{,_lock} and wait_on_bit{,_lock}_io
which are *not* given an action function but implicitly use
a standard one.
The decision to error-out if a signal is pending is now made
based on the 'mode' argument rather than being encoded in the action
function.
All instances of the old wait_on_bit and wait_on_bit_lock which
can use the new version have been changed accordingly and their
action functions have been discarded.
wait_on_bit{_lock} does not return any specific error code in the
event of a signal so the caller must check for non-zero and
interpolate their own error code as appropriate.
The wait_on_bit() call in __fscache_wait_on_invalidate() was
ambiguous as it specified TASK_UNINTERRUPTIBLE but used
fscache_wait_bit_interruptible as an action function.
David Howells confirms this should be uniformly
"uninterruptible"
The main remaining user of wait_on_bit{,_lock}_action is NFS
which needs to use a freezer-aware schedule() call.
A comment in fs/gfs2/glock.c notes that having multiple 'action'
functions is useful as they display differently in the 'wchan'
field of 'ps'. (and /proc/$PID/wchan).
As the new bit_wait{,_io} functions are tagged "__sched", they
will not show up at all, but something higher in the stack. So
the distinction will still be visible, only with different
function names (gds2_glock_wait versus gfs2_glock_dq_wait in the
gfs2/glock.c case).
Since first version of this patch (against 3.15) two new action
functions appeared, on in NFS and one in CIFS. CIFS also now
uses an action function that makes the same freezer aware
schedule call as NFS.
Signed-off-by: NeilBrown <neilb@suse.de>
Acked-by: David Howells <dhowells@redhat.com> (fscache, keys)
Acked-by: Steven Whitehouse <swhiteho@redhat.com> (gfs2)
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Steve French <sfrench@samba.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/20140707051603.28027.72349.stgit@notabene.brown
Signed-off-by: Ingo Molnar <mingo@kernel.org>
* bugfixes:
NFS: Don't reset pg_moreio in __nfs_pageio_add_request
NFS: Remove 2 unused variables
nfs: handle multiple reqs in nfs_wb_page_cancel
nfs: handle multiple reqs in nfs_page_async_flush
nfs: change find_request to find_head_request
nfs: nfs_page should take a ref on the head req
nfs: mark nfs_page reqs with flag for extra ref
nfs: only show Posix ACLs in listxattr if actually present
Conflicts:
fs/nfs/write.c
Once we've started sending unstable NFS writes, we do not want to
clear pg_moreio, or we may end up sending the very last request as
a stable write if the commit lists are still empty.
Do, however, reset pg_moreio in the case where we end up having to
recoalesce the write if an attempt to use pNFS failed.
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
This patch does away with the cast on void * as it is unnecessary.
The following Coccinelle semantic patch was used for making the change:
@r@
expression x;
void* e;
type T;
identifier f;
@@
(
*((T *)e)
|
((T *)x)[...]
|
((T *)x)->f
|
- (T *)
e
)
Signed-off-by: Himangi Saraogi <himangi774@gmail.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
The current CB_COMPOUND handling code tries to compare the principal
name of the request with the cl_hostname in the client. This is not
guaranteed to ever work, particularly if the client happened to mount
a CNAME of the server or a non-fqdn.
Fix this by instead comparing the cr_principal string with the acceptor
name that we get from gssd. In the event that gssd didn't send one
down (i.e. it was too old), then we fall back to trying to use the
cl_hostname as we do today.
Signed-off-by: Jeff Layton <jlayton@poochiereds.net>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
We got a report of the following warning in Fedora:
BUG: sleeping function called from invalid context at mm/slub.c:969
in_atomic(): 1, irqs_disabled(): 0, pid: 533, name: bash
3 locks held by bash/533:
#0: (&sp->so_delegreturn_mutex){+.+...}, at: [<ffffffffa033da62>] nfs4_proc_lock+0x262/0x910 [nfsv4]
#1: (&nfsi->rwsem){.+.+.+}, at: [<ffffffffa033da6a>] nfs4_proc_lock+0x26a/0x910 [nfsv4]
#2: (&sb->s_type->i_lock_key#23){+.+...}, at: [<ffffffff812998dc>] flock_lock_file_wait+0x8c/0x3a0
CPU: 0 PID: 533 Comm: bash Not tainted 3.15.0-0.rc1.git1.1.fc21.x86_64 #1
Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
0000000000000000 00000000d664ff3c ffff880078b69a70 ffffffff817e82e0
0000000000000000 ffff880078b69a98 ffffffff810cf1a4 0000000000000050
0000000000000050 ffff88007cc01a00 ffff880078b69ad8 ffffffff8121449e
Call Trace:
[<ffffffff817e82e0>] dump_stack+0x4d/0x66
[<ffffffff810cf1a4>] __might_sleep+0x184/0x240
[<ffffffff8121449e>] kmem_cache_alloc_trace+0x4e/0x330
[<ffffffffa0331124>] ? nfs4_release_lockowner+0x74/0x110 [nfsv4]
[<ffffffffa0331124>] nfs4_release_lockowner+0x74/0x110 [nfsv4]
[<ffffffffa0352340>] nfs4_put_lock_state+0x90/0xb0 [nfsv4]
[<ffffffffa0352375>] nfs4_fl_release_lock+0x15/0x20 [nfsv4]
[<ffffffff81297515>] locks_free_lock+0x45/0x90
[<ffffffff8129996c>] flock_lock_file_wait+0x11c/0x3a0
[<ffffffffa033da6a>] ? nfs4_proc_lock+0x26a/0x910 [nfsv4]
[<ffffffffa033301e>] do_vfs_lock+0x1e/0x30 [nfsv4]
[<ffffffffa033da79>] nfs4_proc_lock+0x279/0x910 [nfsv4]
[<ffffffff810dbb26>] ? local_clock+0x16/0x30
[<ffffffff810f5a3f>] ? lock_release_holdtime.part.28+0xf/0x200
[<ffffffffa02f820c>] do_unlk+0x8c/0xc0 [nfs]
[<ffffffffa02f85c5>] nfs_flock+0xa5/0xf0 [nfs]
[<ffffffff8129a6f6>] locks_remove_file+0xb6/0x1e0
[<ffffffff812159d8>] ? kfree+0xd8/0x2d0
[<ffffffff8123bc63>] __fput+0xd3/0x210
[<ffffffff8123bdee>] ____fput+0xe/0x10
[<ffffffff810bfb6d>] task_work_run+0xcd/0xf0
[<ffffffff81019cd1>] do_notify_resume+0x61/0x90
[<ffffffff817fbea2>] int_signal+0x12/0x17
The problem is that NFSv4 is trying to do an allocation from
fl_release_private (in order to send a RELEASE_LOCKOWNER call). That
function can be called while holding the inode->i_lock, and it's
currently set up to do __GFP_WAIT allocations. v4.1 code has a
similar problem.
This patch adds a work_struct to the nfs4_lock_state and has the code
queue the free_lock_state operation to nfsiod.
Reported-by: Josh Stone <jistone@redhat.com>
Signed-off-by: Jeff Layton <jlayton@poochiereds.net>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Do the following set of ops with a file on a NFSv4 mount:
exec 3>>/file/on/nfsv4
flock -x 3
exec 3>&-
You'll see the LOCK request go across the wire, but no LOCKU when the
file is closed.
What happens is that the fd is passed across a fork, and the final close
is done in a different process than the opener. That makes
__nfs4_find_lock_state miss finding the correct lock state because it
uses the fl_pid as a search key. A new one is created, and the locking
code treats it as a delegation stateid (because NFS_LOCK_INITIALIZED
isn't set).
The root cause of this breakage seems to be commit 77041ed9b4
(NFSv4: Ensure the lockowners are labelled using the fl_owner and/or
fl_pid).
That changed it so that flock lockowners are allocated based on the
fl_pid. I think this is incorrect. flock locks should be "owned" by the
struct file, and that is already accounted for in the fl_owner field of
the lock request when it comes through nfs_flock.
This patch basically reverts the above commit and with it, a LOCKU is
sent in the above reproducer.
Signed-off-by: Jeff Layton <jlayton@poochiereds.net>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
If file is not opened by anyone, we do layout return on close
in delegation return.
Signed-off-by: Peng Tao <tao.peng@primarydata.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
If client has valid delegation, do not return layout on close at all.
Signed-off-by: Peng Tao <tao.peng@primarydata.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
