fsnotify: use fsnotify_create_event to allocate the q_overflow event

Currently fsnotify defines a static fsnotify event which is sent when a
group overflows its allotted queue length.  This patch just allocates that
event from the event cache rather than defining it statically.  There is no
known reason that the current implementation is wrong, but this makes sure the
event is initialized and created like any other.
Signed-off-by: Eric Paris <eparis@redhat.com>

fs/notify/notification.c

@@ -56,7 +56,7 @@ static struct kmem_cache *fsnotify_event_holder_cachep;
  * it is needed.  It's refcnt is set 1 at kernel init time and will never
  * get set to 0 so it will never get 'freed'
  */
-static struct fsnotify_event q_overflow_event;
+static struct fsnotify_event *q_overflow_event;
 static atomic_t fsnotify_sync_cookie = ATOMIC_INIT(0);
 
 /**
@@ -195,7 +195,7 @@ int fsnotify_add_notify_event(struct fsnotify_group *group, struct fsnotify_even
 	mutex_lock(&group->notification_mutex);
 
 	if (group->q_len >= group->max_events) {
-		event = &q_overflow_event;
+		event = q_overflow_event;
 		ret = -EOVERFLOW;
 		/* sorry, no private data on the overflow event */
 		priv = NULL;
@@ -412,8 +412,11 @@ __init int fsnotify_notification_init(void)
 	fsnotify_event_cachep = KMEM_CACHE(fsnotify_event, SLAB_PANIC);
 	fsnotify_event_holder_cachep = KMEM_CACHE(fsnotify_event_holder, SLAB_PANIC);
 
-	initialize_event(&q_overflow_event);
-	q_overflow_event.mask = FS_Q_OVERFLOW;
+	q_overflow_event = fsnotify_create_event(NULL, FS_Q_OVERFLOW, NULL,
+						 FSNOTIFY_EVENT_NONE, NULL, 0,
+						 GFP_KERNEL);
+	if (!q_overflow_event)
+		panic("unable to allocate fsnotify q_overflow_event\n");
 
 	return 0;
 }