vfs: allow utimensat() calls to retry once on an ESTALE error

Clearly, we can't handle the NULL filename case, but we can deal with
the case where there's a real pathname.
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/utimes.c

@@ -158,13 +158,17 @@ long do_utimes(int dfd, const char __user *filename, struct timespec *times,
 
 		if (!(flags & AT_SYMLINK_NOFOLLOW))
 			lookup_flags |= LOOKUP_FOLLOW;
-
+retry:
 		error = user_path_at(dfd, filename, lookup_flags, &path);
 		if (error)
 			goto out;
 
 		error = utimes_common(&path, times);
 		path_put(&path);
+		if (retry_estale(error, lookup_flags)) {
+			lookup_flags |= LOOKUP_REVAL;
+			goto retry;
+		}
 	}
 
 out: