[PATCH] inotify: add MOVE_SELF event

This adds a MOVE_SELF event to inotify. It is sent whenever the inode
you are watching is moved. We need this event so that we can catch
something like this:

- app1:
watch /etc/mtab

- app2:
cp /etc/mtab /tmp/mtab-work
mv /etc/mtab /etc/mtab~
mv /tmp/mtab-work /etc/mtab

app1 still thinks it's watching /etc/mtab but it's actually watching
/etc/mtab~.

Signed-off-by: John McCutchan <[e-mail]>
Signed-off-by: Robert Love <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

fs/namei.c

···
 		error = vfs_rename_other(old_dir,old_dentry,new_dir,new_dentry);
 	if (!error) {
 		const char *new_name = old_dentry->d_name.name;
-		fsnotify_move(old_dir, new_dir, old_name, new_name, is_dir, new_dentry->d_inode);
+		fsnotify_move(old_dir, new_dir, old_name, new_name, is_dir,
+			      new_dentry->d_inode, old_dentry->d_inode);
 	}
 	fsnotify_oldname_free(old_name);
 

include/linux/fsnotify.h

···
  */
 static inline void fsnotify_move(struct inode *old_dir, struct inode *new_dir,
 				 const char *old_name, const char *new_name,
-				 int isdir, struct inode *target)
+				 int isdir, struct inode *target, struct inode *source)
 {
 	u32 cookie = inotify_get_cookie();
 
···
 	if (target) {
 		inotify_inode_queue_event(target, IN_DELETE_SELF, 0, NULL);
 		inotify_inode_is_dead(target);
+	}
+
+	if (source) {
+		inotify_inode_queue_event(source, IN_MOVE_SELF, 0, NULL);
 	}
 }
 

include/linux/inotify.h

···
 #define IN_CREATE		0x00000100	/* Subfile was created */
 #define IN_DELETE		0x00000200	/* Subfile was deleted */
 #define IN_DELETE_SELF		0x00000400	/* Self was deleted */
+#define IN_MOVE_SELF		0x00000800	/* Self was moved */
 
 /* the following are legal events.  they are sent as needed to any watch */
 #define IN_UNMOUNT		0x00002000	/* Backing fs was unmounted */
···
  */
 #define IN_ALL_EVENTS	(IN_ACCESS | IN_MODIFY | IN_ATTRIB | IN_CLOSE_WRITE | \
 			 IN_CLOSE_NOWRITE | IN_OPEN | IN_MOVED_FROM | \
-			 IN_MOVED_TO | IN_DELETE | IN_CREATE | IN_DELETE_SELF)
+			 IN_MOVED_TO | IN_DELETE | IN_CREATE | IN_DELETE_SELF | \
+			 IN_MOVE_SELF)
 
 #ifdef __KERNEL__