Re: nvme tcp receive errors

[Sagi Grimberg <sagi@grimberg.me>]

>> What is the workload you are running? have an fio job file?
>> Is this I/O to a raw block device? or with fs or iosched?
> 
> It's O_DIRECT to raw block device using libaio engine. No fs, page
> cache, or io scheduler are used.

I see.

> 
> The fio job is generated by a script that cycles through various sizes,
> rw mixes, and io depth. It is not always consistent on which paricular
> set of parameters are running when the error message is observed,
> though. I can get more details if this will be helpful.

Try out a debug patch [1], and when this happens we can get some more
info on the request itself.

>> Also, I'm assuming that you are using Linux nvmet as the target
>> device?
> 
> Not this time. The target is implemented in a hardware device.

Ha, cool...

[1]:
---
diff --git a/drivers/nvme/host/tcp.c b/drivers/nvme/host/tcp.c
index 69f59d2c5799..b218a41ac088 100644
--- a/drivers/nvme/host/tcp.c
+++ b/drivers/nvme/host/tcp.c
@@ -37,6 +37,14 @@ enum nvme_tcp_send_state {
         NVME_TCP_SEND_DDGST,
  };

+enum nvme_tcp_cmd_state {
+       NVME_TCP_CMD_QUEUED = 0,
+       NVME_TCP_CMD_SEND_PDU,
+       NVME_TCP_CMD_PENDING_DATA,
+       NVME_TCP_CMD_DATA_DONE,
+       NVME_TCP_CMD_DONE,
+};
+
  struct nvme_tcp_request {
         struct nvme_request     req;
         void                    *pdu;
@@ -56,6 +64,7 @@ struct nvme_tcp_request {
         size_t                  offset;
         size_t                  data_sent;
         enum nvme_tcp_send_state state;
+       enum nvme_tcp_cmd_state cmd_state;
  };

  enum nvme_tcp_queue_flags {
@@ -482,6 +491,7 @@ static void nvme_tcp_error_recovery(struct nvme_ctrl 
*ctrl)
  static int nvme_tcp_process_nvme_cqe(struct nvme_tcp_queue *queue,
                 struct nvme_completion *cqe)
  {
+       struct nvme_tcp_request *req;
         struct request *rq;

         rq = blk_mq_tag_to_rq(nvme_tcp_tagset(queue), cqe->command_id);
@@ -493,6 +503,8 @@ static int nvme_tcp_process_nvme_cqe(struct 
nvme_tcp_queue *queue,
                 return -EINVAL;
         }

+       req = blk_mq_rq_to_pdu(rq);
+       req->cmd_state = NVME_TCP_CMD_DONE;
         if (!nvme_try_complete_req(rq, cqe->status, cqe->result))
                 nvme_complete_rq(rq);
         queue->nr_cqe++;
@@ -503,6 +515,7 @@ static int nvme_tcp_process_nvme_cqe(struct 
nvme_tcp_queue *queue,
  static int nvme_tcp_handle_c2h_data(struct nvme_tcp_queue *queue,
                 struct nvme_tcp_data_pdu *pdu)
  {
+       struct nvme_tcp_request *req;
         struct request *rq;

         rq = blk_mq_tag_to_rq(nvme_tcp_tagset(queue), pdu->command_id);
@@ -512,11 +525,12 @@ static int nvme_tcp_handle_c2h_data(struct 
nvme_tcp_queue *queue,
                         nvme_tcp_queue_id(queue), pdu->command_id);
                 return -ENOENT;
         }
+       req = blk_mq_rq_to_pdu(rq);

         if (!blk_rq_payload_bytes(rq)) {
                 dev_err(queue->ctrl->ctrl.device,
-                       "queue %d tag %#x unexpected data\n",
-                       nvme_tcp_queue_id(queue), rq->tag);
+                       "queue %d tag %#x unexpected data cmd_state %d\n",
+                       nvme_tcp_queue_id(queue), rq->tag, req->cmd_state);
                 return -EIO;
         }

@@ -755,7 +769,9 @@ static int nvme_tcp_recv_data(struct nvme_tcp_queue 
*queue, struct sk_buff *skb,
                         nvme_tcp_ddgst_final(queue->rcv_hash, 
&queue->exp_ddgst);
                         queue->ddgst_remaining = NVME_TCP_DIGEST_LENGTH;
                 } else {
+                       req->cmd_state = NVME_TCP_CMD_DATA_DONE;
                         if (pdu->hdr.flags & NVME_TCP_F_DATA_SUCCESS) {
+                               req->cmd_state = NVME_TCP_CMD_DONE;
                                 nvme_tcp_end_request(rq, NVME_SC_SUCCESS);
                                 queue->nr_cqe++;
                         }
@@ -796,7 +812,10 @@ static int nvme_tcp_recv_ddgst(struct 
nvme_tcp_queue *queue,
         if (pdu->hdr.flags & NVME_TCP_F_DATA_SUCCESS) {
                 struct request *rq = 
blk_mq_tag_to_rq(nvme_tcp_tagset(queue),
                                                 pdu->command_id);
+               struct nvme_tcp_request *req;

+               req = blk_mq_rq_to_pdu(rq);
+               req->cmd_state = NVME_TCP_CMD_DONE;
                 nvme_tcp_end_request(rq, NVME_SC_SUCCESS);
                 queue->nr_cqe++;
         }
@@ -944,6 +963,7 @@ static int nvme_tcp_try_send_data(struct 
nvme_tcp_request *req)
                                 nvme_tcp_ddgst_final(queue->snd_hash,
                                         &req->ddgst);
                                 req->state = NVME_TCP_SEND_DDGST;
+                               req->cmd_state = NVME_TCP_CMD_DATA_DONE;
                                 req->offset = 0;
                         } else {
                                 nvme_tcp_done_send_req(queue);
@@ -979,6 +999,7 @@ static int nvme_tcp_try_send_cmd_pdu(struct 
nvme_tcp_request *req)

         len -= ret;
         if (!len) {
+               req->cmd_state = req->data_len ? 
NVME_TCP_CMD_PENDING_DATA : NVME_TCP_CMD_DATA_DONE;
                 if (inline_data) {
                         req->state = NVME_TCP_SEND_DATA;
                         if (queue->data_digest)
@@ -2329,6 +2350,7 @@ static blk_status_t nvme_tcp_queue_rq(struct 
blk_mq_hw_ctx *hctx,

         blk_mq_start_request(rq);

+       req->cmd_state = NVME_TCP_CMD_QUEUED;
         nvme_tcp_queue_request(req, true, bd->last);

         return BLK_STS_OK;
---

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