[PATCH 5/6] nvme-tcp: avoid IO error and repeated request completion

Chao Leng
2021-01-05T07:20:11Z

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 completed 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 when 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/tcp.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/nvme/host/tcp.c b/drivers/nvme/host/tcp.c
index 1ba659927442..a81683ce8cff 100644
--- a/drivers/nvme/host/tcp.c
+++ b/drivers/nvme/host/tcp.c
@@ -2306,7 +2306,7 @@ static blk_status_t nvme_tcp_queue_rq(struct blk_mq_hw_ctx *hctx,

ret = nvme_tcp_setup_cmd_pdu(ns, rq);
if (unlikely(ret))
- return ret;
+ return nvme_try_complete_failed_req(rq, ret);

blk_mq_start_request(rq);