fscache: Fix dead object requeue

[mirror_ubuntu-zesty-kernel.git] / fs / fscache / object.c

diff --git a/fs/fscache/object.c b/fs/fscache/object.c
index be02a086ed9b1a43ca236c8c9846c67865bb9e32..7a182c87f37805f1a5fa6719f5cc06cf3dd38552 100644 (file)
--- a/fs/fscache/object.c
+++ b/fs/fscache/object.c
@@ -30,6 +30,7 @@ static const struct fscache_state *fscache_look_up_object(struct fscache_object
 static const struct fscache_state *fscache_object_available(struct fscache_object *, int);
 static const struct fscache_state *fscache_parent_ready(struct fscache_object *, int);
 static const struct fscache_state *fscache_update_object(struct fscache_object *, int);
+static const struct fscache_state *fscache_object_dead(struct fscache_object *, int);
 
 #define __STATE_NAME(n) fscache_osm_##n
 #define STATE(n) (&__STATE_NAME(n))
@@ -91,7 +92,7 @@ static WORK_STATE(LOOKUP_FAILURE,     "LCFL", fscache_lookup_failure);
 static WORK_STATE(KILL_OBJECT,         "KILL", fscache_kill_object);
 static WORK_STATE(KILL_DEPENDENTS,     "KDEP", fscache_kill_dependents);
 static WORK_STATE(DROP_OBJECT,         "DROP", fscache_drop_object);
-static WORK_STATE(OBJECT_DEAD,         "DEAD", (void*)2UL);
+static WORK_STATE(OBJECT_DEAD,         "DEAD", fscache_object_dead);
 
 static WAIT_STATE(WAIT_FOR_INIT,       "?INI",
                  TRANSIT_TO(INIT_OBJECT,       1 << FSCACHE_OBJECT_EV_NEW_CHILD));
@@ -229,6 +230,10 @@ execute_work_state:
        event = -1;
        if (new_state == NO_TRANSIT) {
                _debug("{OBJ%x} %s notrans", object->debug_id, state->name);
+               if (unlikely(state == STATE(OBJECT_DEAD))) {
+                       _leave(" [dead]");
+                       return;
+               }
                fscache_enqueue_object(object);
                event_mask = object->oob_event_mask;
                goto unmask_events;
@@ -239,7 +244,7 @@ execute_work_state:
        object->state = state = new_state;
 
        if (state->work) {
-               if (unlikely(state->work == ((void *)2UL))) {
+               if (unlikely(state == STATE(OBJECT_DEAD))) {
                        _leave(" [dead]");
                        return;
                }
@@ -1083,3 +1088,20 @@ void fscache_object_mark_killed(struct fscache_object *object,
        }
 }
 EXPORT_SYMBOL(fscache_object_mark_killed);
+
+/*
+ * The object is dead.  We can get here if an object gets queued by an event
+ * that would lead to its death (such as EV_KILL) when the dispatcher is
+ * already running (and so can be requeued) but hasn't yet cleared the event
+ * mask.
+ */
+static const struct fscache_state *fscache_object_dead(struct fscache_object *object,
+                                                      int event)
+{
+       if (!test_and_set_bit(FSCACHE_OBJECT_RUN_AFTER_DEAD,
+                             &object->flags))
+               return NO_TRANSIT;
+
+       WARN(true, "FS-Cache object redispatched after death");
+       return NO_TRANSIT;
+}