fanotify:drop notification if they exist in the outgoing queue

[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 3ffb9dbcab08090f7f47113a3d1173f62d922326..c35c1175c4cfbd1384a941069a77fdcb55dbcaaa 100644 (file)
--- a/fs/notify/fanotify/fanotify.c
+++ b/fs/notify/fanotify/fanotify.c
@@ -6,6 +6,45 @@
 
 #include "fanotify.h"
 
+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) &&
+           (old->data_type == new->data_type)) {
+               switch (old->data_type) {
+               case (FSNOTIFY_EVENT_PATH):
+                       if ((old->path.mnt == new->path.mnt) &&
+                           (old->path.dentry == new->path.dentry))
+                               return true;
+               case (FSNOTIFY_EVENT_NONE):
+                       return true;
+               default:
+                       BUG();
+               };
+       }
+       return false;
+}
+
+static int fanotify_merge(struct list_head *list, struct fsnotify_event *event)
+{
+       struct fsnotify_event_holder *holder;
+       struct fsnotify_event *test_event;
+
+       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;
+       }
+
+       return 0;
+}
+
 static int fanotify_handle_event(struct fsnotify_group *group, struct fsnotify_event *event)
 {
        int ret;
@@ -21,8 +60,10 @@ static int fanotify_handle_event(struct fsnotify_group *group, struct fsnotify_e
 
        pr_debug("%s: group=%p event=%p\n", __func__, group, event);
 
-       ret = fsnotify_add_notify_event(group, event, NULL, NULL);
-
+       ret = fsnotify_add_notify_event(group, event, NULL, fanotify_merge);
+       /* -EEXIST means this event was merged with another, not that it was an error */
+       if (ret == -EEXIST)
+               ret = 0;
        return ret;
 }