FS-Cache: Make sure FSCACHE_COOKIE_LOOKING_UP cleared on lookup failure
David Howells [Thu, 19 Nov 2009 18:11:41 +0000 (18:11 +0000)]
We must make sure that FSCACHE_COOKIE_LOOKING_UP is cleared on lookup failure
(if an object reaches the LC_DYING state), and we should clear it before
clearing FSCACHE_COOKIE_CREATING.

If this doesn't happen then fscache_wait_for_deferred_lookup() may hold
allocation and retrieval operations indefinitely until they're interrupted by
signals - which in turn pins the dying object until they go away.

Signed-off-by: David Howells <dhowells@redhat.com>

fs/fscache/object.c

index 1a1afa8..74bc562 100644 (file)
@@ -105,6 +105,7 @@ static inline void fscache_done_parent_op(struct fscache_object *object)
 static void fscache_object_state_machine(struct fscache_object *object)
 {
        enum fscache_object_state new_state;
+       struct fscache_cookie *cookie;
 
        ASSERT(object != NULL);
 
@@ -158,11 +159,17 @@ static void fscache_object_state_machine(struct fscache_object *object)
 
                spin_lock(&object->lock);
                object->state = FSCACHE_OBJECT_DYING;
-               if (object->cookie &&
-                   test_and_clear_bit(FSCACHE_COOKIE_CREATING,
-                                      &object->cookie->flags))
-                       wake_up_bit(&object->cookie->flags,
-                                   FSCACHE_COOKIE_CREATING);
+               cookie = object->cookie;
+               if (cookie) {
+                       if (test_and_clear_bit(FSCACHE_COOKIE_LOOKING_UP,
+                                              &cookie->flags))
+                               wake_up_bit(&cookie->flags,
+                                           FSCACHE_COOKIE_LOOKING_UP);
+                       if (test_and_clear_bit(FSCACHE_COOKIE_CREATING,
+                                              &cookie->flags))
+                               wake_up_bit(&cookie->flags,
+                                           FSCACHE_COOKIE_CREATING);
+               }
                spin_unlock(&object->lock);
 
                fscache_done_parent_op(object);