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fscache: don't leak cookie access refs if invalidation is in progress or failed

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commit fb24771faf72a2fd62b3b6287af3c610c3ec9cf1 upstream.

It's possible for a request to invalidate a fscache_cookie will come in
while we're already processing an invalidation. If that happens we
currently take an extra access reference that will leak. Only call
__fscache_begin_cookie_access if the FSCACHE_COOKIE_DO_INVALIDATE bit
was previously clear.

Also, ensure that we attempt to clear the bit when the cookie is
"FAILED" and put the reference to avoid an access leak.

Fixes: 85e4ea1049c7 ("fscache: Fix invalidation/lookup race")
Suggested-by: David Howells <dhowells@redhat.com>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Jeff Layton 2022-08-05 06:42:45 -04:00 committed by Greg Kroah-Hartman
parent af412b2525
commit 7a369dc87b
1 changed files with 5 additions and 2 deletions
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7
fs/fscache/cookie.c
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@ -739,6 +739,9 @@ again_locked:
fallthrough;
case FSCACHE_COOKIE_STATE_FAILED:
if (test_and_clear_bit(FSCACHE_COOKIE_DO_INVALIDATE, &cookie->flags))
fscache_end_cookie_access(cookie, fscache_access_invalidate_cookie_end);
if (atomic_read(&cookie->n_accesses) != 0)
break;
if (test_bit(FSCACHE_COOKIE_DO_RELINQUISH, &cookie->flags)) {
@ -1063,8 +1066,8 @@ void __fscache_invalidate(struct fscache_cookie *cookie,
return;
case FSCACHE_COOKIE_STATE_LOOKING_UP:
__fscache_begin_cookie_access(cookie, fscache_access_invalidate_cookie);
set_bit(FSCACHE_COOKIE_DO_INVALIDATE, &cookie->flags);
if (!test_and_set_bit(FSCACHE_COOKIE_DO_INVALIDATE, &cookie->flags))
__fscache_begin_cookie_access(cookie, fscache_access_invalidate_cookie);
fallthrough;
case FSCACHE_COOKIE_STATE_CREATING:
spin_unlock(&cookie->lock);