nfsd: fix layout fence worker double-reference race

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The workqueue core clears WORK_STRUCT_PENDING before the callback
is invoked, so delayed_work_pending() in lm_breaker_timedout() can
return false while the fence worker is already running. This lets
the breaker take a duplicate sc_count reference and schedule a new
worker that coalesces with the in-progress one. The extra reference
is never put, leaking the layout stateid.

Replace the racy delayed_work_pending() check with an
ls_fence_inflight boolean set atomically with
refcount_inc_not_zero() under ls_lock, and cleared under ls_lock
before the final nfs4_put_stid() on the dispose path; the retry
path intentionally retains it.  Remove the self-rearm
mod_delayed_work() at the top of the worker.

Fixes: f52792f484 ("NFSD: Enforce timeout on layout recall and integrate lease manager fencing")
Cc: stable@vger.kernel.org
Assisted-by: kres:claude-opus-4-7
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Link: https://patch.msgid.link/20260531-nfsd-testing-v1-6-7bfa481b0540@kernel.org
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

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Jeff Layton 2026-05-31 08:07:03 -04:00 • committed by Chuck Lever

parent 6247023fbb

commit 8580571227

2 changed files with 16 additions and 12 deletions

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27

fs/nfsd/nfs4layouts.c

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1

fs/nfsd/state.h

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