nvme-fabrics: avoid double completions in nvmf_fail_nonready_command

When reconnecting, the request may be completed with
NVME_SC_HOST_PATH_ERROR in nvmf_fail_nonready_command, which currently
set the state of the request to MQ_RQ_IN_FLIGHT before calling
nvme_complete_rq.  When this happens for a request that is freed by
the caller, such as nvme_submit_user_cmd, in the worst case the request
could be completed again in tear down process.

Instead of calling blk_mq_start_request from nvmf_fail_nonready_command,
just use the new nvme_host_path_error helper to complete the command
without starting it.
Signed-off-by: Chao Leng <lengchao@huawei.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>

drivers/nvme/host/fabrics.c

@@ -552,11 +552,7 @@ blk_status_t nvmf_fail_nonready_command(struct nvme_ctrl *ctrl,
 	    !test_bit(NVME_CTRL_FAILFAST_EXPIRED, &ctrl->flags) &&
 	    !blk_noretry_request(rq) && !(rq->cmd_flags & REQ_NVME_MPATH))
 		return BLK_STS_RESOURCE;
-
-	nvme_req(rq)->status = NVME_SC_HOST_PATH_ERROR;
-	blk_mq_start_request(rq);
-	nvme_complete_rq(rq);
-	return BLK_STS_OK;
+	return nvme_host_path_error(rq);
 }
 EXPORT_SYMBOL_GPL(nvmf_fail_nonready_command);