static struct io_kiocb *__io_req_find_next(struct io_kiocb *req)
{
	req->flags &= ~REQ_F_LINK_HEAD;
	if (req->flags & REQ_F_LINK_TIMEOUT)
		io_kill_linked_timeout(req);

	/*
	 * If LINK is set, we have dependent requests in this chain. If we
	 * didn't fail this request, queue the first one up, moving any other
	 * dependencies to the next request. In case of failure, fail the rest
	 * of the chain.
	 */
	if (likely(!(req->flags & REQ_F_FAIL_LINK)))
		return io_req_link_next(req);
	io_fail_links(req);
	return NULL;
}
static struct io_kiocb *__io_req_find_next(struct io_kiocb *req)
{
	req->flags &= ~REQ_F_LINK_HEAD;
	if (req->flags & REQ_F_LINK_TIMEOUT)
		io_kill_linked_timeout(req);

	 
	if (likely(!(req->flags & REQ_F_FAIL_LINK)))
		return io_req_link_next(req);
	io_fail_links(req);
	return NULL;
}