fanotify: merge notification events with different masks

[net-next-2.6.git] / fs / notify / fanotify / fanotify.c

diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c
index c35c1175c4cfbd1384a941069a77fdcb55dbcaaa..8e574d6f6a80f9a24de812aacff8a9b0b73328f8 100644 (file)
--- a/fs/notify/fanotify/fanotify.c
+++ b/fs/notify/fanotify/fanotify.c
@@ -10,8 +10,7 @@ static bool should_merge(struct fsnotify_event *old, struct fsnotify_event *new)
 {
        pr_debug("%s: old=%p new=%p\n", __func__, old, new);
 
-       if ((old->mask == new->mask) &&
-           (old->to_tell == new->to_tell) &&
+       if ((old->to_tell == new->to_tell) &&
            (old->data_type == new->data_type)) {
                switch (old->data_type) {
                case (FSNOTIFY_EVENT_PATH):
@@ -29,20 +28,42 @@ static bool should_merge(struct fsnotify_event *old, struct fsnotify_event *new)
 
 static int fanotify_merge(struct list_head *list, struct fsnotify_event *event)
 {
-       struct fsnotify_event_holder *holder;
+       struct fsnotify_event_holder *test_holder;
        struct fsnotify_event *test_event;
+       struct fsnotify_event *new_event;
+       int ret = 0;
 
        pr_debug("%s: list=%p event=%p\n", __func__, list, event);
 
        /* and the list better be locked by something too! */
 
-       list_for_each_entry_reverse(holder, list, event_list) {
-               test_event = holder->event;
-               if (should_merge(test_event, event))
-                       return -EEXIST;
+       list_for_each_entry_reverse(test_holder, list, event_list) {
+               test_event = test_holder->event;
+               if (should_merge(test_event, event)) {
+                       ret = -EEXIST;
+
+                       /* if they are exactly the same we are done */
+                       if (test_event->mask == event->mask)
+                               goto out;
+
+                       /* can't allocate memory, merge was no possible */
+                       new_event = fsnotify_clone_event(test_event);
+                       if (unlikely(!new_event)) {
+                               ret = 0;
+                               goto out;
+                       }
+
+                       /* build new event and replace it on the list */
+                       new_event->mask = (test_event->mask | event->mask);
+                       fsnotify_replace_event(test_holder, new_event);
+                       /* match ref from fsnotify_clone_event() */
+                       fsnotify_put_event(new_event);
+
+                       break;
+               }
        }
-
-       return 0;
+out:
+       return ret;
 }
 
 static int fanotify_handle_event(struct fsnotify_group *group, struct fsnotify_event *event)