[PATCH net-next RFC v1 06/10] nvme-tcp: Add DDP data-path
Boris Pismenny
borisp at mellanox.com
Wed Sep 30 12:20:06 EDT 2020
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 at mellanox.com>
Signed-off-by: Ben Ben-Ishay <benishay at mellanox.com>
Signed-off-by: Or Gerlitz <ogerlitz at mellanox.com>
Signed-off-by: Yoray Zack <yorayz at mellanox.com>
---
drivers/nvme/host/tcp.c | 121 ++++++++++++++++++++++++++++++++++++++--
1 file changed, 117 insertions(+), 4 deletions(-)
diff --git a/drivers/nvme/host/tcp.c b/drivers/nvme/host/tcp.c
index 06711ac095f2..7bd97f856677 100644
--- a/drivers/nvme/host/tcp.c
+++ b/drivers/nvme/host/tcp.c
@@ -56,6 +56,11 @@ 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 {
@@ -231,10 +236,76 @@ static inline size_t nvme_tcp_pdu_last_send(struct nvme_tcp_request *req,
#ifdef CONFIG_TCP_DDP
bool nvme_tcp_resync_request(struct sock *sk, u32 seq, u32 flags);
+void nvme_tcp_ddp_teardown_done(void *ddp_ctx);
const struct tcp_ddp_ulp_ops nvme_tcp_ddp_ulp_ops __read_mostly = {
+
.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,
+ uint16_t 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)) {
+ pr_info_ratelimited("%s: netdev not found\n", __func__);
+ 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);
+ req->offloaded = false;
+ return ret;
+}
+
+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, cpu_to_le16(req->status << 1), req->result))
+ nvme_complete_rq(rq);
+}
+
+static
+int nvme_tcp_setup_ddp(struct nvme_tcp_queue *queue,
+ uint16_t 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;
+
+ req->offloaded = false;
+
+ if (unlikely(!netdev)) {
+ pr_info_ratelimited("%s: netdev not found\n", __func__);
+ return -EINVAL;
+ }
+
+ req->ddp.command_id = command_id;
+ 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);
+
+ 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 nvme_tcp_config *config)
@@ -351,6 +422,25 @@ bool nvme_tcp_resync_request(struct sock *sk, u32 seq, u32 flags)
#else
+static
+int nvme_tcp_setup_ddp(struct nvme_tcp_queue *queue,
+ uint16_t command_id,
+ struct request *rq)
+{
+ return -EINVAL;
+}
+
+static
+int nvme_tcp_teardown_ddp(struct nvme_tcp_queue *queue,
+ uint16_t command_id,
+ struct request *rq)
+{
+ return -EINVAL;
+}
+
+void nvme_tcp_ddp_teardown_done(void *ddp_ctx)
+{}
+
static
int nvme_tcp_offload_socket(struct nvme_tcp_queue *queue,
struct nvme_tcp_config *config)
@@ -630,6 +720,7 @@ 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);
@@ -641,8 +732,15 @@ 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);
+ req = blk_mq_rq_to_pdu(rq);
+ if (req->offloaded) {
+ req->status = cqe->status;
+ req->result = cqe->result;
+ nvme_tcp_teardown_ddp(queue, cqe->command_id, rq);
+ } else {
+ if (!nvme_try_complete_req(rq, cqe->status, cqe->result))
+ nvme_complete_rq(rq);
+ }
queue->nr_cqe++;
return 0;
@@ -836,9 +934,18 @@ 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)
{
union nvme_result res = {};
+ 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;
- if (!nvme_try_complete_req(rq, cpu_to_le16(status << 1), res))
- nvme_complete_rq(rq);
+ if (req->offloaded) {
+ req->status = cpu_to_le16(status << 1);
+ req->result = res;
+ nvme_tcp_teardown_ddp(queue, pdu->command_id, rq);
+ } else {
+ if (!nvme_try_complete_req(rq, cpu_to_le16(status << 1), res))
+ nvme_complete_rq(rq);
+ }
}
static int nvme_tcp_recv_data(struct nvme_tcp_queue *queue, struct sk_buff *skb,
@@ -1115,6 +1222,7 @@ 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;
@@ -1123,6 +1231,10 @@ static int nvme_tcp_try_send_cmd_pdu(struct nvme_tcp_request *req)
else
flags |= MSG_EOR;
+ if (test_bit(NVME_TCP_Q_OFFLOADS, &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));
@@ -2448,6 +2560,7 @@ 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))
--
2.24.1
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