This is a note to let you know that I've just added the patch titled
fscache: Fix invalidation/lookup race
to the 5.18-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
fscache-fix-invalidation-lookup-race.patch
and it can be found in the queue-5.18 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 85e4ea1049c70fb99de5c6057e835d151fb647da Mon Sep 17 00:00:00 2001
From: David Howells <dhowells@xxxxxxxxxx>
Date: Wed, 20 Apr 2022 14:27:17 +0100
Subject: fscache: Fix invalidation/lookup race
From: David Howells <dhowells@xxxxxxxxxx>
commit 85e4ea1049c70fb99de5c6057e835d151fb647da upstream.
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: d24af13e2e23 ("fscache: Implement cookie invalidation")
Reported-by: Max Kellermann <mk@xxxxxxxxxx>
Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
Tested-by: Max Kellermann <mk@xxxxxxxxxx>
Link: https://lore.kernel.org/r/YlWWbpW5Foynjllo@xxxxxxxxxxxxxxxx-ag [1]
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/fscache/cookie.c | 15 ++++++++++++++-
include/linux/fscache.h | 1 +
2 files changed, 15 insertions(+), 1 deletion(-)
--- a/fs/fscache/cookie.c
+++ b/fs/fscache/cookie.c
@@ -517,7 +517,14 @@ static void fscache_perform_lookup(struc
}
fscache_see_cookie(cookie, fscache_cookie_see_active);
- fscache_set_cookie_state(cookie, FSCACHE_COOKIE_STATE_ACTIVE);
+ spin_lock(&cookie->lock);
+ if (test_and_clear_bit(FSCACHE_COOKIE_DO_INVALIDATE, &cookie->flags))
+ __fscache_set_cookie_state(cookie,
+ FSCACHE_COOKIE_STATE_INVALIDATING);
+ else
+ __fscache_set_cookie_state(cookie, FSCACHE_COOKIE_STATE_ACTIVE);
+ spin_unlock(&cookie->lock);
+ wake_up_cookie_state(cookie);
trace = fscache_access_lookup_cookie_end;
out:
@@ -752,6 +759,9 @@ again_locked:
spin_lock(&cookie->lock);
}
+ if (test_and_clear_bit(FSCACHE_COOKIE_DO_INVALIDATE, &cookie->flags))
+ fscache_end_cookie_access(cookie, fscache_access_invalidate_cookie_end);
+
switch (state) {
case FSCACHE_COOKIE_STATE_RELINQUISHING:
fscache_see_cookie(cookie, fscache_cookie_see_relinquish);
@@ -1048,6 +1058,9 @@ void __fscache_invalidate(struct fscache
return;
case FSCACHE_COOKIE_STATE_LOOKING_UP:
+ __fscache_begin_cookie_access(cookie, fscache_access_invalidate_cookie);
+ set_bit(FSCACHE_COOKIE_DO_INVALIDATE, &cookie->flags);
+ fallthrough;
case FSCACHE_COOKIE_STATE_CREATING:
spin_unlock(&cookie->lock);
_leave(" [look %x]", cookie->inval_counter);
--- a/include/linux/fscache.h
+++ b/include/linux/fscache.h
@@ -129,6 +129,7 @@ struct fscache_cookie {
#define FSCACHE_COOKIE_DO_PREP_TO_WRITE 12 /* T if cookie needs write preparation */
#define FSCACHE_COOKIE_HAVE_DATA 13 /* T if this cookie has data stored */
#define FSCACHE_COOKIE_IS_HASHED 14 /* T if this cookie is hashed */
+#define FSCACHE_COOKIE_DO_INVALIDATE 15 /* T if cookie needs invalidation */
enum fscache_cookie_state state;
u8 advice; /* FSCACHE_ADV_* */
Patches currently in stable-queue which might be from dhowells@xxxxxxxxxx are
queue-5.18/fscache-fix-invalidation-lookup-race.patch
queue-5.18/fscache-fix-if-condition-in-fscache_wait_on_volume_collision.patch
