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From: Mike Snitzer <snitzer@redhat.com>
To: Christoph Hellwig <hch@lst.de>, Jens Axboe <axboe@kernel.dk>
Cc: dm-devel@redhat.com, linux-block@vger.kernel.org,
	linux-nvme@lists.infradead.org
Subject: [PATCH v4 2/3] nvme: allow local retry and proper failover for REQ_FAILFAST_TRANSPORT
Date: Fri, 16 Apr 2021 19:53:28 -0400
Message-ID: <20210416235329.49234-3-snitzer@redhat.com> (raw)
In-Reply-To: <20210416235329.49234-1-snitzer@redhat.com>

REQ_FAILFAST_TRANSPORT is set by upper layer software that handles
multipathing. Unlike SCSI, NVMe's error handling was specifically
designed to handle local retry for non-path errors. As such, allow
NVMe's local retry mechanism to be used for requests marked with
REQ_FAILFAST_TRANSPORT.

In this way, the mechanism of NVMe multipath or other multipath are
now equivalent. The mechanism is: non path related error will be
retried locally, path related error is handled by multipath.

Also, introduce FAILUP handling for REQ_FAILFAST_TRANSPORT. Update
NVMe to allow failover of requests marked with either REQ_NVME_MPATH
or REQ_FAILFAST_TRANSPORT. This allows such requests to be given a
disposition of either FAILOVER or FAILUP respectively.

nvme_complete_rq() is updated to call nvme_failup_req() if
nvme_decide_disposition() returns FAILUP. nvme_failup_req() ensures
the request is completed with a retryable path error.

Signed-off-by: Mike Snitzer <snitzer@redhat.com>
---
 drivers/nvme/host/core.c | 17 ++++++++++++++---
 1 file changed, 14 insertions(+), 3 deletions(-)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index 540d6fd8ffef..a12b10a1383c 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -299,6 +299,7 @@ enum nvme_disposition {
 	COMPLETE,
 	RETRY,
 	FAILOVER,
+	FAILUP,
 };
 
 static inline enum nvme_disposition nvme_decide_disposition(struct request *req)
@@ -306,15 +307,16 @@ static inline enum nvme_disposition nvme_decide_disposition(struct request *req)
 	if (likely(nvme_req(req)->status == 0))
 		return COMPLETE;
 
-	if (blk_noretry_request(req) ||
+	if ((req->cmd_flags & (REQ_FAILFAST_DEV | REQ_FAILFAST_DRIVER)) ||
 	    (nvme_req(req)->status & NVME_SC_DNR) ||
 	    nvme_req(req)->retries >= nvme_max_retries)
 		return COMPLETE;
 
-	if (req->cmd_flags & REQ_NVME_MPATH) {
+	if (req->cmd_flags & (REQ_NVME_MPATH | REQ_FAILFAST_TRANSPORT)) {
 		if (nvme_is_path_error(nvme_req(req)->status) ||
 		    blk_queue_dying(req->q))
-			return FAILOVER;
+			return (req->cmd_flags & REQ_NVME_MPATH) ?
+				FAILOVER : FAILUP;
 	} else {
 		if (blk_queue_dying(req->q))
 			return COMPLETE;
@@ -336,6 +338,12 @@ static inline void nvme_end_req(struct request *req)
 	blk_mq_end_request(req, status);
 }
 
+static inline void nvme_failup_req(struct request *req)
+{
+	nvme_req(req)->status = NVME_SC_HOST_PATH_ERROR;
+	nvme_end_req(req);
+}
+
 void nvme_complete_rq(struct request *req)
 {
 	trace_nvme_complete_rq(req);
@@ -354,6 +362,9 @@ void nvme_complete_rq(struct request *req)
 	case FAILOVER:
 		nvme_failover_req(req);
 		return;
+	case FAILUP:
+		nvme_failup_req(req);
+		return;
 	}
 }
 EXPORT_SYMBOL_GPL(nvme_complete_rq);
-- 
2.15.0


  parent reply index

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-16 23:53 [PATCH v3 0/4] nvme: improve error handling and ana_state to work well with dm-multipath Mike Snitzer
2021-04-16 23:53 ` [PATCH v4 1/3] nvme: return BLK_STS_DO_NOT_RETRY if the DNR bit is set Mike Snitzer
2021-04-20  9:34   ` Christoph Hellwig
2021-04-16 23:53 ` Mike Snitzer [this message]
2021-04-16 23:53 ` [PATCH v4 3/3] nvme: decouple basic ANA log page re-read support from native multipathing Mike Snitzer
2021-04-20  9:34   ` Christoph Hellwig
2021-04-20 14:17     ` Mike Snitzer
2021-04-17  0:02 ` [PATCH v4 0/4] nvme: improve error handling and ana_state to work well with dm-multipath Mike Snitzer
2021-04-19 14:56   ` Mike Snitzer
2021-04-20  9:37 ` [PATCH v3 " Christoph Hellwig
2021-04-20 14:38   ` Mike Snitzer
2021-04-20 15:46     ` Laurence Oberman
2021-05-01 11:58       ` Hannes Reinecke
2021-05-01 15:19         ` Mike Snitzer

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