io_uring: remove redundant check

mainline inclusion
from mainline-5.5-rc1
commit f70193d6
category: feature
bugzilla: https://bugzilla.openeuler.org/show_bug.cgi?id=27
CVE: NA
---------------------------

Pass any IORING_OP_LINK_TIMEOUT request further, where it will
eventually fail in io_issue_sqe().
Signed-off-by: NPavel Begunkov <asml.silence@gmail.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>
Signed-off-by: NZhihao Cheng <chengzhihao1@huawei.com>
Signed-off-by: Nyangerkun <yangerkun@huawei.com>
Reviewed-by: Nzhangyi (F) <yi.zhang@huawei.com>
Signed-off-by: NCheng Jian <cj.chengjian@huawei.com>

fs/io_uring.c

@@ -3078,10 +3078,6 @@ static void io_submit_sqe(struct io_kiocb *req, struct io_submit_state *state,
 
 		INIT_LIST_HEAD(&req->link_list);
 		*link = req;
-	} else if (READ_ONCE(s->sqe->opcode) == IORING_OP_LINK_TIMEOUT) {
-		/* Only valid as a linked SQE */
-		ret = -EINVAL;
-		goto err_req;
 	} else {
 		io_queue_sqe(req);
 	}