From 90b8749022bbdd0c94a13182a78f4903b98fd0d7 Mon Sep 17 00:00:00 2001
From: Pavel Begunkov <asml.silence@gmail.com>
Date: Thu, 25 Mar 2021 19:05:14 +0000
Subject: [PATCH] io_uring: maintain CQE order of a failed link
Arguably we want CQEs of linked requests be in a strict order of
submission as it always was. Now if init of a request fails its CQE may
be posted before all prior linked requests including the head of the
link. Fix it by failing it last.
Fixes: de59bc104c24f ("io_uring: fail links more in io_submit_sqe()")
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/b7a96b05832e7ab23ad55f84092a2548c4a888b0.1616699075.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
fs/io_uring.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/fs/io_uring.c b/fs/io_uring.c
index 8c5789b96dbb6e..54ea561db4a556 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -6480,8 +6480,6 @@ static int io_submit_sqe(struct io_ring_ctx *ctx, struct io_kiocb *req,
ret = io_init_req(ctx, req, sqe);
if (unlikely(ret)) {
fail_req:
- io_put_req(req);
- io_req_complete(req, ret);
if (link->head) {
/* fail even hard links since we don't submit */
link->head->flags |= REQ_F_FAIL_LINK;
@@ -6489,6 +6487,8 @@ fail_req:
io_req_complete(link->head, -ECANCELED);
link->head = NULL;
}
+ io_put_req(req);
+ io_req_complete(req, ret);
return ret;
}
ret = io_req_prep(req, sqe);
--
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