[PATCH v4 net-next 07/21] nvme-tcp: Add DDP data-path

Boris Pismenny
2021-02-11T21:12:01Z

Introduce the NVMe-TCP DDP data-path offload.
Using this interface, the NIC hardware will scatter TCP payload directly
to the BIO pages according to the command_id in the PDU.
To maintain the correctness of the network stack, the driver is expected
to construct SKBs that point to the BIO pages.

The data-path interface contains two routines: tcp_ddp_setup/teardown.
The setup provides the mapping from command_id to the request buffers,
while the teardown removes this mapping.

For efficiency, we introduce an asynchronous nvme completion, which is
split between NVMe-TCP and the NIC driver as follows:
NVMe-TCP performs the specific completion, while NIC driver performs the
generic mq_blk completion.

Signed-off-by: Boris Pismenny <borisp@mellanox.com>
Signed-off-by: Ben Ben-Ishay <benishay@mellanox.com>
Signed-off-by: Or Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: Yoray Zack <yorayz@mellanox.com>
---
drivers/nvme/host/tcp.c | 158 +++++++++++++++++++++++++++++++++++++---
1 file changed, 146 insertions(+), 12 deletions(-)

diff --git a/drivers/nvme/host/tcp.c b/drivers/nvme/host/tcp.c
index 36de4391ba76..188e26ab7116 100644
--- a/drivers/nvme/host/tcp.c
+++ b/drivers/nvme/host/tcp.c
@@ -57,6 +57,11 @@ struct nvme_tcp_request {
size_t offset;
size_t data_sent;
enum nvme_tcp_send_state state;
+
+ bool offloaded;
+ struct tcp_ddp_io ddp;
+ __le16 status;
+ union nvme_result result;
};

enum nvme_tcp_queue_flags {
@@ -229,13 +234,82 @@ static inline size_t nvme_tcp_pdu_last_send(struct nvme_tcp_request *req,
return nvme_tcp_pdu_data_left(req) <= len;
}

+static int nvme_tcp_req_map_sg(struct nvme_tcp_request *req, struct request *rq)
+{
+ int ret;
+
+ req->ddp.sg_table.sgl = req->ddp.first_sgl;
+ ret = sg_alloc_table_chained(&req->ddp.sg_table, blk_rq_nr_phys_segments(rq),
+ req->ddp.sg_table.sgl, SG_CHUNK_SIZE);
+ if (ret)
+ return -ENOMEM;
+ req->ddp.nents = blk_rq_map_sg(rq->q, rq, req->ddp.sg_table.sgl);
+ return 0;
+}
+
#ifdef CONFIG_TCP_DDP

static bool nvme_tcp_resync_request(struct sock *sk, u32 seq, u32 flags);
+static void nvme_tcp_ddp_teardown_done(void *ddp_ctx);
static const struct tcp_ddp_ulp_ops nvme_tcp_ddp_ulp_ops = {
.resync_request = nvme_tcp_resync_request,
+ .ddp_teardown_done = nvme_tcp_ddp_teardown_done,
};

+static int nvme_tcp_teardown_ddp(struct nvme_tcp_queue *queue,
+ u16 command_id,
+ struct request *rq)
+{
+ struct nvme_tcp_request *req = blk_mq_rq_to_pdu(rq);
+ struct net_device *netdev = queue->ctrl->offloading_netdev;
+ int ret;
+
+ if (unlikely(!netdev)) {
+ dev_info_ratelimited(queue->ctrl->ctrl.device, "netdev not found\n");
+ return -EINVAL;
+ }
+
+ ret = netdev->tcp_ddp_ops->tcp_ddp_teardown(netdev, queue->sock->sk,
+ &req->ddp, rq);
+ sg_free_table_chained(&req->ddp.sg_table, SG_CHUNK_SIZE);
+ return ret;
+}
+
+static void nvme_tcp_ddp_teardown_done(void *ddp_ctx)
+{
+ struct request *rq = ddp_ctx;
+ struct nvme_tcp_request *req = blk_mq_rq_to_pdu(rq);
+
+ if (!nvme_try_complete_req(rq, req->status, req->result))
+ nvme_complete_rq(rq);
+}
+
+static int nvme_tcp_setup_ddp(struct nvme_tcp_queue *queue,
+ u16 command_id,
+ struct request *rq)
+{
+ struct nvme_tcp_request *req = blk_mq_rq_to_pdu(rq);
+ struct net_device *netdev = queue->ctrl->offloading_netdev;
+ int ret;
+
+ if (unlikely(!netdev)) {
+ dev_info_ratelimited(queue->ctrl->ctrl.device, "netdev not found\n");
+ return -EINVAL;
+ }
+
+ req->ddp.command_id = command_id;
+ ret = nvme_tcp_req_map_sg(req, rq);
+ if (ret)
+ return -ENOMEM;
+
+ ret = netdev->tcp_ddp_ops->tcp_ddp_setup(netdev,
+ queue->sock->sk,
+ &req->ddp);
+ if (!ret)
+ req->offloaded = true;
+ return ret;
+}
+
static int nvme_tcp_offload_socket(struct nvme_tcp_queue *queue)
{
struct net_device *netdev = queue->ctrl->offloading_netdev;
@@ -343,7 +417,7 @@ static void nvme_tcp_resync_response(struct nvme_tcp_queue *queue,
return;

if (unlikely(!netdev)) {
- pr_info_ratelimited("%s: netdev not found\n", __func__);
+ dev_info_ratelimited(queue->ctrl->ctrl.device, "netdev not found\n");
return;
}

@@ -368,6 +442,20 @@ static bool nvme_tcp_resync_request(struct sock *sk, u32 seq, u32 flags)

#else

+static int nvme_tcp_setup_ddp(struct nvme_tcp_queue *queue,
+ u16 command_id,
+ struct request *rq)
+{
+ return -EINVAL;
+}
+
+static int nvme_tcp_teardown_ddp(struct nvme_tcp_queue *queue,
+ u16 command_id,
+ struct request *rq)
+{
+ return -EINVAL;
+}
+
static int nvme_tcp_offload_socket(struct nvme_tcp_queue *queue)
{
return -EINVAL;
@@ -643,6 +731,24 @@ static void nvme_tcp_error_recovery(struct nvme_ctrl *ctrl)
queue_work(nvme_reset_wq, &to_tcp_ctrl(ctrl)->err_work);
}

+static void nvme_tcp_complete_request(struct request *rq,
+ __le16 status,
+ union nvme_result result,
+ __u16 command_id)
+{
+ struct nvme_tcp_request *req = blk_mq_rq_to_pdu(rq);
+ struct nvme_tcp_queue *queue = req->queue;
+
+ if (req->offloaded) {
+ req->status = status;
+ req->result = result;
+ nvme_tcp_teardown_ddp(queue, command_id, rq);
+ } else {
+ if (!nvme_try_complete_req(rq, status, result))
+ nvme_complete_rq(rq);
+ }
+}
+
static int nvme_tcp_process_nvme_cqe(struct nvme_tcp_queue *queue,
struct nvme_completion *cqe)
{
@@ -657,10 +763,8 @@ static int nvme_tcp_process_nvme_cqe(struct nvme_tcp_queue *queue,
return -EINVAL;
}

- if (!nvme_try_complete_req(rq, cqe->status, cqe->result))
- nvme_complete_rq(rq);
+ nvme_tcp_complete_request(rq, cqe->status, cqe->result, cqe->command_id);
queue->nr_cqe++;
-
return 0;
}

@@ -849,10 +953,39 @@ static int nvme_tcp_recv_pdu(struct nvme_tcp_queue *queue, struct sk_buff *skb,

static inline void nvme_tcp_end_request(struct request *rq, u16 status)
{
+ struct nvme_tcp_request *req = blk_mq_rq_to_pdu(rq);
+ struct nvme_tcp_queue *queue = req->queue;
+ struct nvme_tcp_data_pdu *pdu = (void *)queue->pdu;
union nvme_result res = {};

- if (!nvme_try_complete_req(rq, cpu_to_le16(status << 1), res))
- nvme_complete_rq(rq);
+ nvme_tcp_complete_request(rq, cpu_to_le16(status << 1), res, pdu->command_id);
+}
+
+
+static int nvme_tcp_consume_skb(struct nvme_tcp_queue *queue, struct sk_buff *skb,
+ unsigned int *offset, struct iov_iter *iter, int recv_len)
+{
+ int ret;
+
+#ifdef CONFIG_TCP_DDP
+ if (test_bit(NVME_TCP_Q_OFF_DDP, &queue->flags)) {
+ if (queue->data_digest)
+ ret = skb_ddp_copy_and_hash_datagram_iter(skb, *offset, iter, recv_len,
+ queue->rcv_hash);
+ else
+ ret = skb_ddp_copy_datagram_iter(skb, *offset, iter, recv_len);
+ } else {
+#endif
+ if (queue->data_digest)
+ ret = skb_copy_and_hash_datagram_iter(skb, *offset, iter, recv_len,
+ queue->rcv_hash);
+ else
+ ret = skb_copy_datagram_iter(skb, *offset, iter, recv_len);
+#ifdef CONFIG_TCP_DDP
+ }
+#endif
+
+ return ret;
}

static int nvme_tcp_recv_data(struct nvme_tcp_queue *queue, struct sk_buff *skb,
@@ -899,12 +1032,7 @@ static int nvme_tcp_recv_data(struct nvme_tcp_queue *queue, struct sk_buff *skb,
recv_len = min_t(size_t, recv_len,
iov_iter_count(&req->iter));

- if (queue->data_digest)
- ret = skb_copy_and_hash_datagram_iter(skb, *offset,
- &req->iter, recv_len, queue->rcv_hash);
- else
- ret = skb_copy_datagram_iter(skb, *offset,
- &req->iter, recv_len);
+ ret = nvme_tcp_consume_skb(queue, skb, offset, &req->iter, recv_len);
if (ret) {
dev_err(queue->ctrl->ctrl.device,
"queue %d failed to copy request %#x data",
@@ -1128,6 +1256,7 @@ static int nvme_tcp_try_send_cmd_pdu(struct nvme_tcp_request *req)
bool inline_data = nvme_tcp_has_inline_data(req);
u8 hdgst = nvme_tcp_hdgst_len(queue);
int len = sizeof(*pdu) + hdgst - req->offset;
+ struct request *rq = blk_mq_rq_from_pdu(req);
int flags = MSG_DONTWAIT;
int ret;

@@ -1136,6 +1265,10 @@ static int nvme_tcp_try_send_cmd_pdu(struct nvme_tcp_request *req)
else
flags |= MSG_EOR;

+ if (test_bit(NVME_TCP_Q_OFF_DDP, &queue->flags) &&
+ blk_rq_nr_phys_segments(rq) && rq_data_dir(rq) == READ)
+ nvme_tcp_setup_ddp(queue, pdu->cmd.common.command_id, rq);
+
if (queue->hdr_digest && !req->offset)
nvme_tcp_hdgst(queue->snd_hash, pdu, sizeof(*pdu));

@@ -2441,6 +2574,7 @@ static blk_status_t nvme_tcp_setup_cmd_pdu(struct nvme_ns *ns,
req->data_len = blk_rq_nr_phys_segments(rq) ?
blk_rq_payload_bytes(rq) : 0;
req->curr_bio = rq->bio;
+ req->offloaded = false;

if (rq_data_dir(rq) == WRITE &&
req->data_len <= nvme_tcp_inline_data_size(queue))