inotify: fix inotify oneshot support

During the large inotify rewrite to fsnotify I completely dropped support
for IN_ONESHOT.  Reimplement that support.

Signed-off-by: Eric Paris <eparis@redhat.com>
diff --git a/fs/notify/inotify/inotify_fsnotify.c b/fs/notify/inotify/inotify_fsnotify.c
index daa666a..388a150 100644
--- a/fs/notify/inotify/inotify_fsnotify.c
+++ b/fs/notify/inotify/inotify_fsnotify.c
@@ -126,6 +126,9 @@
 			ret = 0;
 	}
 
+	if (fsn_mark->mask & IN_ONESHOT)
+		fsnotify_destroy_mark(fsn_mark);
+
 	/*
 	 * If we hold the fsn_mark until after the event is on the queue
 	 * IN_IGNORED won't be able to pass this event in the queue