fsnotify: check to make sure all fsnotify bits are unique

This patch adds a check to make sure that all fsnotify bits are unique and we
cannot accidentally use the same bit for 2 different fsnotify event types.
Signed-off-by: NEric Paris <eparis@redhat.com>

fs/notify/fsnotify.c

@@ -275,6 +275,8 @@ EXPORT_SYMBOL_GPL(fsnotify);
 
 static __init int fsnotify_init(void)
 {
+	BUG_ON(hweight32(ALL_FSNOTIFY_EVENTS) != 23);
+
 	return init_srcu_struct(&fsnotify_grp_srcu);
 }
 subsys_initcall(fsnotify_init);

include/linux/fsnotify_backend.h

@@ -64,6 +64,15 @@
 
 #define FS_MOVE			(FS_MOVED_FROM | FS_MOVED_TO)
 
+#define ALL_FSNOTIFY_EVENTS (FS_ACCESS | FS_MODIFY | FS_ATTRIB | \
+			     FS_CLOSE_WRITE | FS_CLOSE_NOWRITE | FS_OPEN | \
+			     FS_MOVED_FROM | FS_MOVED_TO | FS_CREATE | \
+			     FS_DELETE | FS_DELETE_SELF | FS_MOVE_SELF | \
+			     FS_UNMOUNT | FS_Q_OVERFLOW | FS_IN_IGNORED | \
+			     FS_OPEN_PERM | FS_ACCESS_PERM | FS_EXCL_UNLINK | \
+			     FS_IN_ISDIR | FS_IN_ONESHOT | FS_DN_RENAME | \
+			     FS_DN_MULTISHOT | FS_EVENT_ON_CHILD)
+
 struct fsnotify_group;
 struct fsnotify_event;
 struct fsnotify_mark;