[PATCH v3] nvme-tcp: Do not reset transport on data digest errors

Daniel Wagner
2021-08-26T08:22:09Z

The spec says

7.4.6.1 Digest Error handling

When a host detects a data digest error in a C2HData PDU, that host
shall continue processing C2HData PDUs associated with the command and
when the command processing has completed, if a successful status was
returned by the controller, the host shall fail the command with a
non-fatal transport error.

Currently the transport is reseted when a data digest error is
detected. Instead, when a digest error is detected, mark the final
status as NVME_SC_DATA_XFER_ERROR and let the upper layer handle
the error.

In order to keep track of the final result maintain a status field in
nvme_tcp_request object and use it to overwrite the completion queue
status (which might be successful even though a digest error has been
detected) when completing the request.

Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Daniel Wagner <dwagner@suse.de>
---
The status member placed so that it fills up a hole in struct
nvme_tcp_request:

struct nvme_tcp_request {
struct nvme_request req; /* 0 32 */
void * pdu; /* 32 8 */
struct nvme_tcp_queue * queue; /* 40 8 */
u32 data_len; /* 48 4 */
u32 pdu_len; /* 52 4 */
u32 pdu_sent; /* 56 4 */
u16 ttag; /* 60 2 */
u16 status; /* 62 2 */
/* --- cacheline 1 boundary (64 bytes) --- */
struct list_head entry; /* 64 16 */
struct llist_node lentry; /* 80 8 */
__le32 ddgst; /* 88 4 */

/* XXX 4 bytes hole, try to pack */

struct bio * curr_bio; /* 96 8 */
struct iov_iter iter; /* 104 40 */
/* --- cacheline 2 boundary (128 bytes) was 16 bytes ago --- */
size_t offset; /* 144 8 */
size_t data_sent; /* 152 8 */
enum nvme_tcp_send_state state; /* 160 4 */

/* size: 168, cachelines: 3, members: 16 */
/* sum members: 160, holes: 1, sum holes: 4 */
/* padding: 4 */
/* last cacheline: 40 bytes */
};

v3:
- initialize req->status in nvme_tcp_setup_cmd_pdu()
- add rb tag from Hannes

v2:
- https://lore.kernel.org/linux-nvme/20210825124259.28707-1-dwagner@suse.de/
- moved 'status' from nvme_tcp_queue to nvme_tcp_request.

v1:
- https://lore.kernel.org/linux-nvme/20210805121541.77613-1-dwagner@suse.de/

drivers/nvme/host/tcp.c | 23 +++++++++++++++++++----
1 file changed, 19 insertions(+), 4 deletions(-)

diff --git a/drivers/nvme/host/tcp.c b/drivers/nvme/host/tcp.c
index 645025620154..29ef0f74f620 100644
--- a/drivers/nvme/host/tcp.c
+++ b/drivers/nvme/host/tcp.c
@@ -45,6 +45,7 @@ struct nvme_tcp_request {
u32 pdu_len;
u32 pdu_sent;
u16 ttag;
+ u16 status;
struct list_head entry;
struct llist_node lentry;
__le32 ddgst;
@@ -485,7 +486,9 @@ 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;
+ u16 status;

rq = nvme_find_rq(nvme_tcp_tagset(queue), cqe->command_id);
if (!rq) {
@@ -496,7 +499,12 @@ static int nvme_tcp_process_nvme_cqe(struct nvme_tcp_queue *queue,
return -EINVAL;
}

- if (!nvme_try_complete_req(rq, cqe->status, cqe->result))
+ req = blk_mq_rq_to_pdu(rq);
+ status = req->status;
+ if (status == NVME_SC_SUCCESS)
+ status = cqe->status;
+
+ if (!nvme_try_complete_req(rq, status, cqe->result))
nvme_complete_rq(rq);
queue->nr_cqe++;

@@ -758,7 +766,7 @@ static int nvme_tcp_recv_data(struct nvme_tcp_queue *queue, struct sk_buff *skb,
queue->ddgst_remaining = NVME_TCP_DIGEST_LENGTH;
} else {
if (pdu->hdr.flags & NVME_TCP_F_DATA_SUCCESS) {
- nvme_tcp_end_request(rq, NVME_SC_SUCCESS);
+ nvme_tcp_end_request(rq, req->status);
queue->nr_cqe++;
}
nvme_tcp_init_recv_ctx(queue);
@@ -788,18 +796,24 @@ static int nvme_tcp_recv_ddgst(struct nvme_tcp_queue *queue,
return 0;

if (queue->recv_ddgst != queue->exp_ddgst) {
+ struct request *rq = nvme_cid_to_rq(nvme_tcp_tagset(queue),
+ pdu->command_id);
+ struct nvme_tcp_request *req = blk_mq_rq_to_pdu(rq);
+
+ req->status = NVME_SC_DATA_XFER_ERROR;
+
dev_err(queue->ctrl->ctrl.device,
"data digest error: recv %#x expected %#x\n",
le32_to_cpu(queue->recv_ddgst),
le32_to_cpu(queue->exp_ddgst));
- return -EIO;
}

if (pdu->hdr.flags & NVME_TCP_F_DATA_SUCCESS) {
struct request *rq = nvme_cid_to_rq(nvme_tcp_tagset(queue),
pdu->command_id);
+ struct nvme_tcp_request *req = blk_mq_rq_to_pdu(rq);

- nvme_tcp_end_request(rq, NVME_SC_SUCCESS);
+ nvme_tcp_end_request(rq, req->status);
queue->nr_cqe++;
}

@@ -2293,6 +2307,7 @@ static blk_status_t nvme_tcp_setup_cmd_pdu(struct nvme_ns *ns,
return ret;

req->state = NVME_TCP_SEND_CMD_PDU;
+ req->status = NVME_SC_SUCCESS;
req->offset = 0;
req->data_sent = 0;
req->pdu_len = 0;
--
2.29.2