io_uring: simplify io_req_link_next()

mainline inclusion
from mainline-5.5-rc1
commit b18fdf71
category: feature
bugzilla: https://bugzilla.openeuler.org/show_bug.cgi?id=27
CVE: NA
---------------------------

"if (nxt)" is always true, as it was checked in the while's condition.
io_wq_current_is_worker() is unnecessary, as non-async callers don't
pass nxt, so io_queue_async_work() will be called for them anyway.
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

@@ -902,16 +902,7 @@ static void io_req_link_next(struct io_kiocb *req, struct io_kiocb **nxtptr)
 			nxt->flags |= REQ_F_LINK;
 		}
 
-		/*
-		 * If we're in async work, we can continue processing the chain
-		 * in this context instead of having to queue up new async work.
-		 */
-		if (nxt) {
-			if (io_wq_current_is_worker())
 		*nxtptr = nxt;
-			else
-				io_queue_async_work(nxt);
-		}
 		break;
 	}