linux/fs/fscache
David Howells 85e4ea1049 fscache: Fix invalidation/lookup race
If an NFS file is opened for writing and closed, fscache_invalidate() will
be asked to invalidate the file - however, if the cookie is in the
LOOKING_UP state (or the CREATING state), then request to invalidate
doesn't get recorded for fscache_cookie_state_machine() to do something
with.

Fix this by making __fscache_invalidate() set a flag if it sees the cookie
is in the LOOKING_UP state to indicate that we need to go to invalidation.
Note that this requires a count on the n_accesses counter for the state
machine, which that will release when it's done.

fscache_cookie_state_machine() then shifts to the INVALIDATING state if it
sees the flag.

Without this, an nfs file can get corrupted if it gets modified locally and
then read locally as the cache contents may not get updated.

Fixes: d24af13e2e ("fscache: Implement cookie invalidation")
Reported-by: Max Kellermann <mk@cm4all.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Tested-by: Max Kellermann <mk@cm4all.com>
Link: https://lore.kernel.org/r/YlWWbpW5Foynjllo@rabbit.intern.cm-ag [1]
2022-07-05 16:12:55 +01:00
..
cache.c fscache: Use wrapper fscache_set_cache_state() directly when relinquishing 2022-04-08 23:54:37 +01:00
cookie.c fscache: Fix invalidation/lookup race 2022-07-05 16:12:55 +01:00
internal.h fscache: Move fscache_cookies_seq_ops specific code under CONFIG_PROC_FS 2022-04-08 23:54:37 +01:00
io.c fscache: Remove the cookie parameter from fscache_clear_page_bits() 2022-04-08 23:54:37 +01:00
Kconfig fscache: remove FSCACHE_OLD_API Kconfig option 2022-04-08 23:54:37 +01:00
main.c fscache: Implement cookie-level access helpers 2022-01-07 09:22:19 +00:00
Makefile fscache: Provide a means to begin an operation 2022-01-07 09:22:19 +00:00
proc.c fscache: Implement cookie registration 2022-01-07 09:22:19 +00:00
stats.c fscache, cachefiles: Display stat of culling events 2022-01-07 13:43:18 +00:00
volume.c fscache: Fix if condition in fscache_wait_on_volume_collision() 2022-07-05 16:12:20 +01:00