* [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
end of thread, other threads:[~2021-08-27 17:04 UTC | newest] Thread overview: 6+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 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 2021-08-27 17:04 ` Hao Xu
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