nfsd4: add refcount for nfsd4_blocked_lock

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[ Upstream commit 47446d74f1 ]

nbl allocated in nfsd4_lock can be released by a several ways:
directly in nfsd4_lock(), via nfs4_laundromat(), via another nfs
command RELEASE_LOCKOWNER or via nfsd4_callback.
This structure should be refcounted to be used and released correctly
in all these cases.

Refcount is initialized to 1 during allocation and is incremented
when nbl is added into nbl_list/nbl_lru lists.

Usually nbl is linked into both lists together, so only one refcount
is used for both lists.

However nfsd4_lock() should keep in mind that nbl can be present
in one of lists only. This can happen if nbl was handled already
by nfs4_laundromat/nfsd4_callback/etc.

Refcount is decremented if vfs_lock_file() returns FILE_LOCK_DEFERRED,
because nbl can be handled already by nfs4_laundromat/nfsd4_callback/etc.

Refcount is not changed in find_blocked_lock() because of it reuses counter
released after removing nbl from lists.

Signed-off-by: Vasily Averin <vvs@virtuozzo.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

...

This commit is contained in:

Vasily Averin 2021-12-17 09:49:39 +03:00 • committed by Greg Kroah-Hartman

parent 64ff32b8ad

commit 1a197bcedf

2 changed files with 23 additions and 3 deletions

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25

fs/nfsd/nfs4state.c

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1

fs/nfsd/state.h

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