afs: fix the usage of read_seqbegin_or_lock() in afs_lookup_volume_rcu()

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[ Upstream commit 4121b43371 ]

David Howells says:

 (2) afs_lookup_volume_rcu().

     There can be a lot of volumes known by a system.  A thousand would
     require a 10-step walk and this is drivable by remote operation, so I
     think this should probably take a lock on the second pass too.

Make the "seq" counter odd on the 2nd pass, otherwise read_seqbegin_or_lock()
never takes the lock.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
Link: https://lore.kernel.org/r/20231130115606.GA21571@redhat.com/
Signed-off-by: Sasha Levin <sashal@kernel.org>

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Oleg Nesterov 2023-11-30 12:56:06 +01:00 • committed by Greg Kroah-Hartman

parent 91256fcd57

commit eef7c4cd98

1 changed files with 2 additions and 1 deletions

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fs/afs/callback.c

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