FS-Cache: Make sure FSCACHE_COOKIE_LOOKING_UP cleared on lookup failure

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>

1 files changed, 12 insertions, 5 deletions

diff --git a/fs/fscache/object.c b/fs/fscache/object.c
index 1a1afa82f798..74bc562a2cbc 100644
--- a/fs/fscache/object.c
+++ b/fs/fscache/object.c
@@ -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);