vfs: take mnt_child/mnt_mounts to struct mount

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/mount.h b/fs/mount.h
index 452ae41..e4ecf59 100644
--- a/fs/mount.h
+++ b/fs/mount.h
@@ -17,6 +17,8 @@
 	int mnt_count;
 	int mnt_writers;
 #endif
+	struct list_head mnt_mounts;	/* list of children, anchored here */
+	struct list_head mnt_child;	/* and going through their mnt_child */
 };
 
 static inline struct mount *real_mount(struct vfsmount *mnt)