io_uring: prioritise read success path over fails

Rearrange io_read return handling so first we expect it completing
successfully and only then checking for errors, which is a colder path.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/c91c7c2da11815ec8b04b5d872f60dc4cde662c5.1634144845.git.asml.silence@gmail.comSigned-off-by: Jens Axboe <axboe@kernel.dk>

fs/io_uring.c

@@ -3487,7 +3487,7 @@ static int io_read(struct io_kiocb *req, unsigned int issue_flags)
 		ret = 0;
 	} else if (ret == -EIOCBQUEUED) {
 		goto out_free;
-	} else if (ret <= 0 || ret == req->result || !force_nonblock ||
+	} else if (ret == req->result || ret <= 0 || !force_nonblock ||
 		   (req->flags & REQ_F_NOWAIT) || !need_read_all(req)) {
 		/* read all, failed, already did sync or don't want to retry */
 		goto done;