mount_setattr(2): don't mess with LOOKUP_EMPTY

just use CLASS(filename_uflags) + filename_lookup()

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Author: Al Viro

fs/namespace.c

@@ -4978,8 +4978,6 @@ SYSCALL_DEFINE5(mount_setattr, int, dfd, const char __user *, path,
 		lookup_flags &= ~LOOKUP_AUTOMOUNT;
 	if (flags & AT_SYMLINK_NOFOLLOW)
 		lookup_flags &= ~LOOKUP_FOLLOW;
-	if (flags & AT_EMPTY_PATH)
-		lookup_flags |= LOOKUP_EMPTY;
 
 	kattr = (struct mount_kattr) {
 		.lookup_flags	= lookup_flags,
@@ -4992,7 +4990,8 @@ SYSCALL_DEFINE5(mount_setattr, int, dfd, const char __user *, path,
 	if (err <= 0)
 		return err;
 
-	err = user_path_at(dfd, path, kattr.lookup_flags, &target);
+	CLASS(filename_uflags, name)(path, flags);
+	err = filename_lookup(dfd, name, kattr.lookup_flags, &target, NULL);
 	if (!err) {
 		err = do_mount_setattr(&target, &kattr);
 		path_put(&target);