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From: Sagi Grimberg <sagi@grimberg.me>
To: Chao Leng <lengchao@huawei.com>, linux-nvme@lists.infradead.org
Cc: kbusch@kernel.org, axboe@fb.com, hch@lst.de,
	linux-block@vger.kernel.org, axboe@kernel.dk
Subject: Re: [PATCH v2 4/6] nvme-rdma: avoid IO error and repeated request completion
Date: Wed, 13 Jan 2021 16:19:47 -0800	[thread overview]
Message-ID: <07e41b4f-914a-11e8-5638-e2d6408feb3f@grimberg.me> (raw)
In-Reply-To: <20210107033149.15701-5-lengchao@huawei.com>


> When a request is queued failed, blk_status_t is directly returned
> to the blk-mq. If blk_status_t is not BLK_STS_RESOURCE,
> BLK_STS_DEV_RESOURCE, BLK_STS_ZONE_RESOURCE, blk-mq call
> blk_mq_end_request to complete the request with BLK_STS_IOERR.
> In two scenarios, the request should be retried and may succeed.
> First, if work with nvme multipath, the request may be retried
> successfully in another path, because the error is probably related to
> the path. Second, if work without multipath software, the request may
> be retried successfully after error recovery.
> If the request is complete with BLK_STS_IOERR in blk_mq_dispatch_rq_list.
> The state of request may be changed to MQ_RQ_IN_FLIGHT. If free the
> request asynchronously such as in nvme_submit_user_cmd, in extreme
> scenario the request will be repeated freed in tear down.
> If a non-resource error occurs in queue_rq, should directly call
> nvme_complete_rq to complete request and set the state of request to
> MQ_RQ_COMPLETE. nvme_complete_rq will decide to retry, fail over or end
> the request.
> 
> Signed-off-by: Chao Leng <lengchao@huawei.com>
> ---
>   drivers/nvme/host/rdma.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/nvme/host/rdma.c b/drivers/nvme/host/rdma.c
> index df9f6f4549f1..4a89bf44ecdc 100644
> --- a/drivers/nvme/host/rdma.c
> +++ b/drivers/nvme/host/rdma.c
> @@ -2093,7 +2093,7 @@ static blk_status_t nvme_rdma_queue_rq(struct blk_mq_hw_ctx *hctx,
>   unmap_qe:
>   	ib_dma_unmap_single(dev, req->sqe.dma, sizeof(struct nvme_command),
>   			    DMA_TO_DEVICE);
> -	return ret;
> +	return nvme_try_complete_failed_req(rq, ret);

I don't understand this. There are errors that may not be related to
anything that is pathing related (sw bug, memory leak, mapping error,
etc, etc) why should we return this one-shot error?

WARNING: multiple messages have this Message-ID (diff)
From: Sagi Grimberg <sagi@grimberg.me>
To: Chao Leng <lengchao@huawei.com>, linux-nvme@lists.infradead.org
Cc: kbusch@kernel.org, axboe@fb.com, linux-block@vger.kernel.org,
	hch@lst.de, axboe@kernel.dk
Subject: Re: [PATCH v2 4/6] nvme-rdma: avoid IO error and repeated request completion
Date: Wed, 13 Jan 2021 16:19:47 -0800	[thread overview]
Message-ID: <07e41b4f-914a-11e8-5638-e2d6408feb3f@grimberg.me> (raw)
In-Reply-To: <20210107033149.15701-5-lengchao@huawei.com>


> When a request is queued failed, blk_status_t is directly returned
> to the blk-mq. If blk_status_t is not BLK_STS_RESOURCE,
> BLK_STS_DEV_RESOURCE, BLK_STS_ZONE_RESOURCE, blk-mq call
> blk_mq_end_request to complete the request with BLK_STS_IOERR.
> In two scenarios, the request should be retried and may succeed.
> First, if work with nvme multipath, the request may be retried
> successfully in another path, because the error is probably related to
> the path. Second, if work without multipath software, the request may
> be retried successfully after error recovery.
> If the request is complete with BLK_STS_IOERR in blk_mq_dispatch_rq_list.
> The state of request may be changed to MQ_RQ_IN_FLIGHT. If free the
> request asynchronously such as in nvme_submit_user_cmd, in extreme
> scenario the request will be repeated freed in tear down.
> If a non-resource error occurs in queue_rq, should directly call
> nvme_complete_rq to complete request and set the state of request to
> MQ_RQ_COMPLETE. nvme_complete_rq will decide to retry, fail over or end
> the request.
> 
> Signed-off-by: Chao Leng <lengchao@huawei.com>
> ---
>   drivers/nvme/host/rdma.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/nvme/host/rdma.c b/drivers/nvme/host/rdma.c
> index df9f6f4549f1..4a89bf44ecdc 100644
> --- a/drivers/nvme/host/rdma.c
> +++ b/drivers/nvme/host/rdma.c
> @@ -2093,7 +2093,7 @@ static blk_status_t nvme_rdma_queue_rq(struct blk_mq_hw_ctx *hctx,
>   unmap_qe:
>   	ib_dma_unmap_single(dev, req->sqe.dma, sizeof(struct nvme_command),
>   			    DMA_TO_DEVICE);
> -	return ret;
> +	return nvme_try_complete_failed_req(rq, ret);

I don't understand this. There are errors that may not be related to
anything that is pathing related (sw bug, memory leak, mapping error,
etc, etc) why should we return this one-shot error?

_______________________________________________
Linux-nvme mailing list
Linux-nvme@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-nvme

  reply	other threads:[~2021-01-14  0:32 UTC|newest]

Thread overview: 44+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-07  3:31 [PATCH v2 0/6] avoid repeated request completion and IO error Chao Leng
2021-01-07  3:31 ` Chao Leng
2021-01-07  3:31 ` [PATCH v2 1/6] blk-mq: introduce blk_mq_set_request_complete Chao Leng
2021-01-07  3:31   ` Chao Leng
2021-01-14  0:17   ` Sagi Grimberg
2021-01-14  0:17     ` Sagi Grimberg
2021-01-14  6:50     ` Chao Leng
2021-01-14  6:50       ` Chao Leng
2021-01-07  3:31 ` [PATCH v2 2/6] nvme-core: introduce complete failed request Chao Leng
2021-01-07  3:31   ` Chao Leng
2021-01-21  8:14   ` Hannes Reinecke
2021-01-22  1:45     ` Chao Leng
2021-01-07  3:31 ` [PATCH v2 3/6] nvme-fabrics: avoid repeated request completion for nvmf_fail_nonready_command Chao Leng
2021-01-07  3:31   ` Chao Leng
2021-01-07  3:31 ` [PATCH v2 4/6] nvme-rdma: avoid IO error and repeated request completion Chao Leng
2021-01-07  3:31   ` Chao Leng
2021-01-14  0:19   ` Sagi Grimberg [this message]
2021-01-14  0:19     ` Sagi Grimberg
2021-01-14  6:55     ` Chao Leng
2021-01-14  6:55       ` Chao Leng
2021-01-14 21:25       ` Sagi Grimberg
2021-01-14 21:25         ` Sagi Grimberg
2021-01-15  2:53         ` Chao Leng
2021-01-15  2:53           ` Chao Leng
2021-01-16  1:18           ` Sagi Grimberg
2021-01-16  1:18             ` Sagi Grimberg
2021-01-18  3:22             ` Chao Leng
2021-01-18  3:22               ` Chao Leng
2021-01-18 17:49               ` Christoph Hellwig
2021-01-18 17:49                 ` Christoph Hellwig
2021-01-19  1:50                 ` Chao Leng
2021-01-19  1:50                   ` Chao Leng
2021-01-20 21:35               ` Sagi Grimberg
2021-01-20 21:35                 ` Sagi Grimberg
2021-01-21  1:34                 ` Chao Leng
2021-01-21  1:34                   ` Chao Leng
2021-01-07  3:31 ` [PATCH v2 5/6] nvme-tcp: " Chao Leng
2021-01-07  3:31   ` Chao Leng
2021-01-07  3:31 ` [PATCH v2 6/6] nvme-fc: " Chao Leng
2021-01-07  3:31   ` Chao Leng
2021-01-14  0:15 ` [PATCH v2 0/6] avoid repeated request completion and IO error Sagi Grimberg
2021-01-14  0:15   ` Sagi Grimberg
2021-01-14  6:50   ` Chao Leng
2021-01-14  6:50     ` Chao Leng

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