io_uring: break links for failed defer

mainline inclusion
from mainline-5.5-rc1
commit d3b35796
category: feature
bugzilla: https://bugzilla.openeuler.org/show_bug.cgi?id=27
CVE: NA
---------------------------

If io_req_defer() failed, it needs to cancel a dependant link.
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

@@ -2957,6 +2957,8 @@ static void io_queue_sqe(struct io_kiocb *req)
 	if (ret) {
 		if (ret != -EIOCBQUEUED) {
 			io_cqring_add_event(req, ret);
+			if (req->flags & REQ_F_LINK)
+				req->flags |= REQ_F_FAIL_LINK;
 			io_double_put_req(req);
 		}
 	} else
@@ -2989,6 +2991,8 @@ static void io_queue_link_head(struct io_kiocb *req, struct io_kiocb *shadow)
 		if (ret != -EIOCBQUEUED) {
 err:
 			io_cqring_add_event(req, ret);
+			if (req->flags & REQ_F_LINK)
+				req->flags |= REQ_F_FAIL_LINK;
 			io_double_put_req(req);
 			if (shadow)
 				__io_free_req(shadow);