fsnotify: intoduce a notification merge argument

Each group can define their own notification (and secondary_q) merge
function.  Inotify does tail drop, fanotify does matching and drop which
can actually allocate a completely new event.  But for fanotify to properly
deal with permissions events it needs to know the new event which was
ultimately added to the notification queue.  This patch just implements a
void ** argument which is passed to the merge function.  fanotify can use
this field to pass the new event back to higher layers.

Signed-off-by: Eric Paris <eparis@redhat.com>
for fanotify to properly deal with permissions events

1 files changed, 5 insertions, 2 deletions

diff --git a/fs/notify/notification.c b/fs/notify/notification.c
index 7fc8d004084c..2d50a40ab1e4 100644
--- a/fs/notify/notification.c
+++ b/fs/notify/notification.c
@@ -137,7 +137,10 @@ struct fsnotify_event_private_data *fsnotify_remove_priv_from_event(struct fsnot
  */
 int fsnotify_add_notify_event(struct fsnotify_group *group, struct fsnotify_event *event,
                               struct fsnotify_event_private_data *priv,
-                              int (*merge)(struct list_head *, struct fsnotify_event *))
+                              int (*merge)(struct list_head *,
+                                           struct fsnotify_event *,
+                                           void **arg),
+                              void **arg)
 {
         struct fsnotify_event_holder *holder = NULL;
         struct list_head *list = &group->notification_list;
@@ -170,7 +173,7 @@ alloc_holder:
         if (!list_empty(list) && merge) {
                 int ret;
 
-                ret = merge(list, event);
+                ret = merge(list, event, arg);
                 if (ret) {
                         mutex_unlock(&group->notification_mutex);
                         if (holder != &event->holder)