* [PATCH for-5.15 v3 0/2] fix failed linkchain code logic
@ 2021-08-27 9:46 Hao Xu
2021-08-27 9:46 ` [PATCH 1/2] io_uring: remove redundant req_set_fail() Hao Xu
` (3 more replies)
0 siblings, 4 replies; 6+ messages in thread
From: Hao Xu @ 2021-08-27 9:46 UTC (permalink / raw)
To: Jens Axboe; +Cc: io-uring, Pavel Begunkov, Joseph Qi
the first patch is code clean.
the second is the main one, which refactors linkchain failure path to
fix a problem, detail in the commit message.
v1-->v2
- update patch with Pavel's suggestion.
v2-->v3
- move req->result initiation to better place
- add helpers for failing link node
Hao Xu (2):
io_uring: remove redundant req_set_fail()
io_uring: fix failed linkchain code logic
fs/io_uring.c | 62 ++++++++++++++++++++++++++++++++++++++-------------
1 file changed, 47 insertions(+), 15 deletions(-)
--
2.24.4
^ permalink raw reply [flat|nested] 6+ messages in thread
* [PATCH 1/2] io_uring: remove redundant req_set_fail()
2021-08-27 9:46 [PATCH for-5.15 v3 0/2] fix failed linkchain code logic Hao Xu
@ 2021-08-27 9:46 ` Hao Xu
2021-08-27 9:46 ` [PATCH 2/2] io_uring: fix failed linkchain code logic Hao Xu
` (2 subsequent siblings)
3 siblings, 0 replies; 6+ messages in thread
From: Hao Xu @ 2021-08-27 9:46 UTC (permalink / raw)
To: Jens Axboe; +Cc: io-uring, Pavel Begunkov, Joseph Qi
req_set_fail() in io_submit_sqe() is redundant, remove it.
Signed-off-by: Hao Xu <[email protected]>
---
fs/io_uring.c | 1 -
1 file changed, 1 deletion(-)
diff --git a/fs/io_uring.c b/fs/io_uring.c
index d9534c72dc4b..3598319b1340 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -6631,7 +6631,6 @@ static int io_submit_sqe(struct io_ring_ctx *ctx, struct io_kiocb *req,
fail_req:
if (link->head) {
/* fail even hard links since we don't submit */
- req_set_fail(link->head);
io_req_complete_failed(link->head, -ECANCELED);
link->head = NULL;
}
--
2.24.4
^ permalink raw reply related [flat|nested] 6+ messages in thread
* [PATCH 2/2] io_uring: fix failed linkchain code logic
2021-08-27 9:46 [PATCH for-5.15 v3 0/2] fix failed linkchain code logic Hao Xu
2021-08-27 9:46 ` [PATCH 1/2] io_uring: remove redundant req_set_fail() Hao Xu
@ 2021-08-27 9:46 ` Hao Xu
2021-08-27 11:01 ` [PATCH for-5.15 v3 0/2] " Pavel Begunkov
2021-08-27 13:27 ` Jens Axboe
3 siblings, 0 replies; 6+ messages in thread
From: Hao Xu @ 2021-08-27 9:46 UTC (permalink / raw)
To: Jens Axboe; +Cc: io-uring, Pavel Begunkov, Joseph Qi
Given a linkchain like this:
req0(link_flag)-->req1(link_flag)-->...-->reqn(no link_flag)
There is a problem:
- if some intermediate linked req like req1 's submittion fails, reqs
after it won't be cancelled.
- sqpoll disabled: maybe it's ok since users can get the error info
of req1 and stop submitting the following sqes.
- sqpoll enabled: definitely a problem, the following sqes will be
submitted in the next round.
The solution is to refactor the code logic to:
- if a linked req's submittion fails, just mark it and the head(if it
exists) as REQ_F_FAIL. Leverage req->result to indicate whether it
is failed or cancelled.
- submit or fail the whole chain when we come to the end of it.
Signed-off-by: Hao Xu <[email protected]>
---
fs/io_uring.c | 61 +++++++++++++++++++++++++++++++++++++++------------
1 file changed, 47 insertions(+), 14 deletions(-)
diff --git a/fs/io_uring.c b/fs/io_uring.c
index 3598319b1340..4c83ec227d85 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -1175,6 +1175,12 @@ static inline void req_set_fail(struct io_kiocb *req)
req->flags |= REQ_F_FAIL;
}
+static inline void req_fail_link_node(struct io_kiocb *req, int res)
+{
+ req_set_fail(req);
+ req->result = res;
+}
+
static void io_ring_ctx_ref_free(struct percpu_ref *ref)
{
struct io_ring_ctx *ctx = container_of(ref, struct io_ring_ctx, refs);
@@ -1931,11 +1937,16 @@ static void io_fail_links(struct io_kiocb *req)
req->link = NULL;
while (link) {
+ long res = -ECANCELED;
+
+ if (link->flags & REQ_F_FAIL)
+ res = link->result;
+
nxt = link->link;
link->link = NULL;
trace_io_uring_fail_link(req, link);
- io_cqring_fill_event(link->ctx, link->user_data, -ECANCELED, 0);
+ io_cqring_fill_event(link->ctx, link->user_data, res, 0);
io_put_req_deferred(link);
link = nxt;
}
@@ -6519,8 +6530,10 @@ static inline void io_queue_sqe(struct io_kiocb *req)
if (unlikely(req->ctx->drain_active) && io_drain_req(req))
return;
- if (likely(!(req->flags & REQ_F_FORCE_ASYNC))) {
+ if (likely(!(req->flags & (REQ_F_FORCE_ASYNC | REQ_F_FAIL)))) {
__io_queue_sqe(req);
+ } else if (req->flags & REQ_F_FAIL) {
+ io_req_complete_failed(req, req->result);
} else {
int ret = io_req_prep_async(req);
@@ -6629,19 +6642,34 @@ 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:
+ /* fail even hard links since we don't submit */
if (link->head) {
- /* fail even hard links since we don't submit */
- io_req_complete_failed(link->head, -ECANCELED);
- link->head = NULL;
+ /*
+ * we can judge a link req is failed or cancelled by if
+ * REQ_F_FAIL is set, but the head is an exception since
+ * it may be set REQ_F_FAIL because of other req's failure
+ * so let's leverage req->result to distinguish if a head
+ * is set REQ_F_FAIL because of its failure or other req's
+ * failure so that we can set the correct ret code for it.
+ * init result here to avoid affecting the normal path.
+ */
+ if (!(link->head->flags & REQ_F_FAIL))
+ req_fail_link_node(link->head, -ECANCELED);
+ } else if (!(req->flags & (REQ_F_LINK | REQ_F_HARDLINK))) {
+ /*
+ * the current req is a normal req, we should return
+ * error and thus break the submittion loop.
+ */
+ io_req_complete_failed(req, ret);
+ return ret;
}
- io_req_complete_failed(req, ret);
- return ret;
+ req_fail_link_node(req, ret);
+ } else {
+ ret = io_req_prep(req, sqe);
+ if (unlikely(ret))
+ goto fail_req;
}
- ret = io_req_prep(req, sqe);
- if (unlikely(ret))
- goto fail_req;
-
/* don't need @sqe from now on */
trace_io_uring_submit_sqe(ctx, req, req->opcode, req->user_data,
req->flags, true,
@@ -6657,9 +6685,14 @@ static int io_submit_sqe(struct io_ring_ctx *ctx, struct io_kiocb *req,
if (link->head) {
struct io_kiocb *head = link->head;
- ret = io_req_prep_async(req);
- if (unlikely(ret))
- goto fail_req;
+ if (!(req->flags & REQ_F_FAIL)) {
+ ret = io_req_prep_async(req);
+ if (unlikely(ret)) {
+ req_fail_link_node(req, ret);
+ if (!(head->flags & REQ_F_FAIL))
+ req_fail_link_node(head, -ECANCELED);
+ }
+ }
trace_io_uring_link(ctx, req, head);
link->last->link = req;
link->last = req;
--
2.24.4
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH for-5.15 v3 0/2] fix failed linkchain code logic
2021-08-27 9:46 [PATCH for-5.15 v3 0/2] fix failed linkchain code logic Hao Xu
2021-08-27 9:46 ` [PATCH 1/2] io_uring: remove redundant req_set_fail() Hao Xu
2021-08-27 9:46 ` [PATCH 2/2] io_uring: fix failed linkchain code logic Hao Xu
@ 2021-08-27 11:01 ` Pavel Begunkov
2021-08-27 13:27 ` Jens Axboe
3 siblings, 0 replies; 6+ messages in thread
From: Pavel Begunkov @ 2021-08-27 11:01 UTC (permalink / raw)
To: Hao Xu, Jens Axboe; +Cc: io-uring, Joseph Qi
On 8/27/21 10:46 AM, Hao Xu wrote:
> the first patch is code clean.
> the second is the main one, which refactors linkchain failure path to
> fix a problem, detail in the commit message.
Looks good, thanks
Reviewed-by: Pavel Begunkov <[email protected]>
> v1-->v2
> - update patch with Pavel's suggestion.
> v2-->v3
> - move req->result initiation to better place
> - add helpers for failing link node
>
> Hao Xu (2):
> io_uring: remove redundant req_set_fail()
> io_uring: fix failed linkchain code logic
>
> fs/io_uring.c | 62 ++++++++++++++++++++++++++++++++++++++-------------
> 1 file changed, 47 insertions(+), 15 deletions(-)
>
--
Pavel Begunkov
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH for-5.15 v3 0/2] fix failed linkchain code logic
2021-08-27 9:46 [PATCH for-5.15 v3 0/2] fix failed linkchain code logic Hao Xu
` (2 preceding siblings ...)
2021-08-27 11:01 ` [PATCH for-5.15 v3 0/2] " Pavel Begunkov
@ 2021-08-27 13:27 ` Jens Axboe
2021-08-27 17:04 ` Hao Xu
3 siblings, 1 reply; 6+ messages in thread
From: Jens Axboe @ 2021-08-27 13:27 UTC (permalink / raw)
To: Hao Xu; +Cc: io-uring, Pavel Begunkov, Joseph Qi
On 8/27/21 3:46 AM, Hao Xu wrote:
> the first patch is code clean.
> the second is the main one, which refactors linkchain failure path to
> fix a problem, detail in the commit message.
Thanks for pulling this one to completion - applied!
--
Jens Axboe
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH for-5.15 v3 0/2] fix failed linkchain code logic
2021-08-27 13:27 ` Jens Axboe
@ 2021-08-27 17:04 ` Hao Xu
0 siblings, 0 replies; 6+ messages in thread
From: Hao Xu @ 2021-08-27 17:04 UTC (permalink / raw)
To: Jens Axboe; +Cc: io-uring, Pavel Begunkov, Joseph Qi
在 2021/8/27 下午9:27, Jens Axboe 写道:
> On 8/27/21 3:46 AM, Hao Xu wrote:
>> the first patch is code clean.
>> the second is the main one, which refactors linkchain failure path to
>> fix a problem, detail in the commit message.
>
> Thanks for pulling this one to completion - applied!
>
sorry for the delay.
^ permalink raw reply [flat|nested] 6+ messages in thread
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2021-08-27 9:46 [PATCH for-5.15 v3 0/2] fix failed linkchain code logic Hao Xu
2021-08-27 9:46 ` [PATCH 1/2] io_uring: remove redundant req_set_fail() Hao Xu
2021-08-27 9:46 ` [PATCH 2/2] io_uring: fix failed linkchain code logic Hao Xu
2021-08-27 11:01 ` [PATCH for-5.15 v3 0/2] " Pavel Begunkov
2021-08-27 13:27 ` Jens Axboe
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