linux-stable.git/fs/lockd/svclock.c, branch linux-rolling-lts

lockd: fix TEST handling when not all permissions are available.

2026-07-04T11:44:14+00:00

[ Upstream commit 0b474240327cebeff08ad429e8ed3cfc6c8ee816 ]

The F_GETLK fcntl can work with either read access or write access or
both.  It can query F_RDLCK and F_WRLCK locks in either case.

However lockd currently treats F_GETLK similar to F_SETLK in that read
access is required to query an F_RDLCK lock and write access is required
to query a F_WRLCK lock.

This is wrong and can cause problems - e.g.  when qemu accesses a
read-only (e.g. iso) filesystem image over NFS (though why it queries
if it can get a write lock - I don't know.  But it does, and this works
with local filesystems).

So we need TEST requests to be handled differently.  To do this:

- change nlm_do_fopen() to accept O_RDWR as a mode and in that case
  succeed if either a O_RDONLY or O_WRONLY file can be opened.
- change nlm_lookup_file() to accept a mode argument from caller,
  instead of deducing base on lock time, and pass that on to nlm_do_fopen()
- change nlm4svc_retrieve_args() and nlmsvc_retrieve_args() to detect
  TEST requests and pass O_RDWR as a mode to nlm_lookup_file, passing
  the same mode as before for other requests.  Also set
   lock->fl.c.flc_file to whichever file is available for TEST requests.
- change nlmsvc_testlock() to also not calculate the mode, but to use
  whatever was stored in lock->fl.c.flc_file.

This behaviour of lockd - requesting O_WRONLY access to TEST for
exclusive locks - has been present at least since git history began.
However it was hidden until recently because knfsd ignored the access
requested by lockd and required only READ access for all locking
requests (unless the underlying filesystem provided an f_op->open
function which checked access permissions).

The commit mentioned in Fixes: below changed nfsd_permission() to NOT
override the access request for LOCK requests and this exposed the bug
that we are now fixing.

Note that there is another issue that this patch does not address.
The flock(.., LOCK_EX) call is permitted on a read-only file descriptor.
Linux NFS maps this to NLM locking as whole-file byte-range locks.
nfsd will see this as though it were fcntl( F_SETLK (F_WRLCK)) and will
now require write access, which it might not be able to get.
It is not clear if this is a problem in practice, or what the best
solution might be.  So no attempt is made to address it.

Reported-by: Tj 
Link: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1128861
Fixes: 4cc9b9f2bf4d ("nfsd: refine and rename NFSD_MAY_LOCK")
Reviewed-by: Jeff Layton 
Signed-off-by: NeilBrown 
Signed-off-by: Chuck Lever 
Signed-off-by: Sasha Levin

lockd: fix vfs_test_lock() calls

2026-01-08T09:17:10+00:00

commit a49a2a1baa0c553c3548a1c414b6a3c005a8deba upstream.

Usage of vfs_test_lock() is somewhat confused.  Documentation suggests
it is given a "lock" but this is not the case.  It is given a struct
file_lock which contains some details of the sort of lock it should be
looking for.

In particular passing a "file_lock" containing fl_lmops or fl_ops is
meaningless and possibly confusing.

This is particularly problematic in lockd.  nlmsvc_testlock() receives
an initialised "file_lock" from xdr-decode, including manager ops and an
owner.  It then mistakenly passes this to vfs_test_lock() which might
replace the owner and the ops.  This can lead to confusion when freeing
the lock.

The primary role of the 'struct file_lock' passed to vfs_test_lock() is
to report a conflicting lock that was found, so it makes more sense for
nlmsvc_testlock() to pass "conflock", which it uses for returning the
conflicting lock.

With this change, freeing of the lock is not confused and code in
__nlm4svc_proc_test() and __nlmsvc_proc_test() can be simplified.

Documentation for vfs_test_lock() is improved to reflect its real
purpose, and a WARN_ON_ONCE() is added to avoid a similar problem in the
future.

Reported-by: Olga Kornievskaia 
Closes: https://lore.kernel.org/all/20251021130506.45065-1-okorniev@redhat.com
Signed-off-by: NeilBrown 
Fixes: 20fa19027286 ("nfs: add export operations")
Cc: stable@vger.kernel.org
Reviewed-by: Jeff Layton 
Signed-off-by: Chuck Lever 
Signed-off-by: Greg Kroah-Hartman

lockd: Remove space before newline

2025-09-21T23:24:50+00:00

There is an extraneous space before a newline in a dprintk message.
Remove the space.

Signed-off-by: Colin Ian King 
Signed-off-by: Chuck Lever

Merge tag 'nfsd-6.13' of git://git.kernel.org/pub/scm/linux/kernel/git/cel/linux

2024-11-26T20:59:30+00:00

Pull nfsd updates from Chuck Lever:
 "Jeff Layton contributed a scalability improvement to NFSD's NFSv4
  backchannel session implementation. This improvement is intended to
  increase the rate at which NFSD can safely recall NFSv4 delegations
  from clients, to avoid the need to revoke them. Revoking requires a
  slow state recovery process.

  A wide variety of bug fixes and other incremental improvements make up
  the bulk of commits in this series. As always I am grateful to the
  NFSD contributors, reviewers, testers, and bug reporters who
  participated during this cycle"

* tag 'nfsd-6.13' of git://git.kernel.org/pub/scm/linux/kernel/git/cel/linux: (72 commits)
  nfsd: allow for up to 32 callback session slots
  nfs_common: must not hold RCU while calling nfsd_file_put_local
  nfsd: get rid of include ../internal.h
  nfsd: fix nfs4_openowner leak when concurrent nfsd4_open occur
  NFSD: Add nfsd4_copy time-to-live
  NFSD: Add a laundromat reaper for async copy state
  NFSD: Block DESTROY_CLIENTID only when there are ongoing async COPY operations
  NFSD: Handle an NFS4ERR_DELAY response to CB_OFFLOAD
  NFSD: Free async copy information in nfsd4_cb_offload_release()
  NFSD: Fix nfsd4_shutdown_copy()
  NFSD: Add a tracepoint to record canceled async COPY operations
  nfsd: make nfsd4_session->se_flags a bool
  nfsd: remove nfsd4_session->se_bchannel
  nfsd: make use of warning provided by refcount_t
  nfsd: Don't fail OP_SETCLIENTID when there are too many clients.
  svcrdma: fix miss destroy percpu_counter in svc_rdma_proc_init()
  xdrgen: Remove program_stat_to_errno() call sites
  xdrgen: Update the files included in client-side source code
  xdrgen: Remove check for "nfs_ok" in C templates
  xdrgen: Remove tracepoint call site
  ...

lockd: Remove unused parameter to nlmsvc_testlock()

2024-11-19T01:23:04+00:00

The nlm_cookie parameter has been unused since commit 09802fd2a8ca
("lockd: rip out deferred lock handling from testlock codepath").

Reviewed-by: Jeff Layton 
Reviewed-by: NeilBrown 
Signed-off-by: Chuck Lever

NLM/NFSD: Fix lock notifications for async-capable filesystems

2024-10-01T15:00:18+00:00

Instead of checking just the exportfs flag, use the new
locks_can_async_lock() helper which allows NLM and NFSD to once again
support lock notifications for all filesystems which use posix_lock_file().

Signed-off-by: Benjamin Coddington 
Link: https://lore.kernel.org/r/865c40da44af67939e8eb560d17a26c9c50f23e0.1726083391.git.bcodding@redhat.com
Reviewed-by: Jeff Layton 
Signed-off-by: Christian Brauner

lockd: adapt to breakup of struct file_lock

2024-02-05T12:11:43+00:00

Most of the existing APIs have remained the same, but subsystems that
access file_lock fields directly need to reach into struct
file_lock_core now.

Signed-off-by: Jeff Layton 
Link: https://lore.kernel.org/r/20240131-flsplit-v3-40-c6129007ee8d@kernel.org
Reviewed-by: NeilBrown 
Signed-off-by: Christian Brauner

SUNRPC: change how svc threads are asked to exit.

2023-10-16T16:44:04+00:00

svc threads are currently stopped using kthread_stop().  This requires
identifying a specific thread.  However we don't care which thread
stops, just as long as one does.

So instead, set a flag in the svc_pool to say that a thread needs to
die, and have each thread check this flag instead of calling
kthread_should_stop().  The first thread to find and clear this flag
then moves towards exiting.

This removes an explicit dependency on sp_all_threads which will make a
future patch simpler.

Signed-off-by: NeilBrown 
Signed-off-by: Chuck Lever

lockd: fix race in async lock request handling

2023-10-16T16:44:02+00:00

This patch fixes a race in async lock request handling between adding
the relevant struct nlm_block to nlm_blocked list after the request was
sent by vfs_lock_file() and nlmsvc_grant_deferred() does a lookup of the
nlm_block in the nlm_blocked list. It could be that the async request is
completed before the nlm_block was added to the list. This would end
in a -ENOENT and a kernel log message of "lockd: grant for unknown
block".

To solve this issue we add the nlm_block before the vfs_lock_file() call
to be sure it has been added when a possible nlmsvc_grant_deferred() is
called. If the vfs_lock_file() results in an case when it wouldn't be
added to nlm_blocked list, the nlm_block struct will be removed from
this list again.

Reviewed-by: Jeff Layton 
Signed-off-by: Alexander Aring 
Signed-off-by: Chuck Lever

lockd: don't call vfs_lock_file() for pending requests

2023-10-16T16:44:01+00:00

This patch returns nlm_lck_blocked in nlmsvc_lock() when an asynchronous
lock request is pending. During testing I ran into the case with the
side-effects that lockd is waiting for only one lm_grant() callback
because it's already part of the nlm_blocked list. If another
asynchronous for the same nlm_block is triggered two lm_grant()
callbacks will occur but lockd was only waiting for one.

To avoid any change of existing users this handling will only being made
when export_op_support_safe_async_lock() returns true.

Reviewed-by: Jeff Layton 
Signed-off-by: Alexander Aring 
Signed-off-by: Chuck Lever