fsnotify: Remove special handling of mark destruction on group shutdown

Currently we queue all marks for destruction on group shutdown and then
destroy them from fsnotify_destroy_group() instead from a worker thread
which is the usual path. However worker can already be processing some
list of marks to destroy so this does not make 100% all marks are really
destroyed by the time group is shut down. This isn't a big problem as
each mark holds group reference and thus group stays partially alive
until all marks are really freed but there's no point in complicating
our lives - just wait for the delayed work to be finished instead.

Reviewed-by: Miklos Szeredi <mszeredi@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
diff --git a/fs/notify/mark.c b/fs/notify/mark.c
index 21c7791..f916b71 100644
--- a/fs/notify/mark.c
+++ b/fs/notify/mark.c
@@ -703,7 +703,7 @@ void fsnotify_init_mark(struct fsnotify_mark *mark,
  * Destroy all marks in destroy_list, waits for SRCU period to finish before
  * actually freeing marks.
  */
-void fsnotify_mark_destroy_list(void)
+static void fsnotify_mark_destroy_workfn(struct work_struct *work)
 {
 	struct fsnotify_mark *mark, *next;
 	struct list_head private_destroy_list;
@@ -721,7 +721,8 @@ void fsnotify_mark_destroy_list(void)
 	}
 }
 
-static void fsnotify_mark_destroy_workfn(struct work_struct *work)
+/* Wait for all marks queued for destruction to be actually destroyed */
+void fsnotify_wait_marks_destroyed(void)
 {
-	fsnotify_mark_destroy_list();
+	flush_delayed_work(&reaper_work);
 }