vfs: have do_sys_truncate retry once on an ESTALE error

static long do_sys_truncate(const char __user *pathname, loff_t length)

{

	unsigned int lookup_flags = LOOKUP_FOLLOW;

	struct path path;

	int error;

	if (length < 0)	/* sorry, but loff_t says... */

		return -EINVAL;

	error = user_path(pathname, &path);

retry:

	error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path);

	if (!error) {

		error = vfs_truncate(&path, length);

		path_put(&path);

	}

	if (retry_estale(error, lookup_flags)) {

		lookup_flags |= LOOKUP_REVAL;

		goto retry;

	}

	return error;

}