Scott Mayhew 2e47c3cc64 NFSv4: ensure the open stateid seqid doesn't go backwards
We have observed an NFSv4 client receiving a LOCK reply with a status of
NFS4ERR_OLD_STATEID and subsequently retrying the LOCK request with an
earlier seqid value in the stateid.  As this was for a new lockowner,
that would imply that nfs_set_open_stateid_locked() had updated the open
stateid seqid with an earlier value.

Looking at nfs_set_open_stateid_locked(), if the incoming seqid is out
of sequence, the task will sleep on the state->waitq for up to 5
seconds.  If the task waits for the full 5 seconds, then after finishing
the wait it'll update the open stateid seqid with whatever value the
incoming seqid has.  If there are multiple waiters in this scenario,
then the last one to perform said update may not be the one with the
highest seqid.

Add a check to ensure that the seqid can only be incremented, and add a
tracepoint to indicate when old seqids are skipped.

Signed-off-by: Scott Mayhew <smayhew@redhat.com>
Reviewed-by: Benjamin Coddington <bcodding@hammerspace.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
2025-11-23 15:10:08 -05:00
2025-11-15 10:52:01 -08:00
2022-09-28 09:02:20 +02:00
2025-02-19 14:53:27 -07:00
2025-11-16 14:25:38 -08:00
2024-03-18 03:36:32 -06:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.
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