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Message-ID: <9a8041aa-513f-09b9-63f4-3d12db19231c@grimberg.me>
Date: Wed, 3 Feb 2021 00:51:45 -0800
From: Sagi Grimberg <sagi@...mberg.me>
To: Boris Pismenny <borisp@...lanox.com>, dsahern@...il.com,
kuba@...nel.org, davem@...emloft.net, saeedm@...dia.com,
hch@....de, axboe@...com, kbusch@...nel.org,
viro@...iv.linux.org.uk, edumazet@...gle.com, smalin@...vell.com
Cc: boris.pismenny@...il.com, linux-nvme@...ts.infradead.org,
netdev@...r.kernel.org, benishay@...dia.com, ogerlitz@...dia.com,
yorayz@...dia.com, Ben Ben-Ishay <benishay@...lanox.com>,
Or Gerlitz <ogerlitz@...lanox.com>,
Yoray Zack <yorayz@...lanox.com>
Subject: Re: [PATCH v3 net-next 07/21] nvme-tcp: Add DDP data-path
On 2/1/21 2:04 AM, Boris Pismenny wrote:
> 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@...lanox.com>
> Signed-off-by: Ben Ben-Ishay <benishay@...lanox.com>
> Signed-off-by: Or Gerlitz <ogerlitz@...lanox.com>
> Signed-off-by: Yoray Zack <yorayz@...lanox.com>
> ---
> drivers/nvme/host/tcp.c | 141 +++++++++++++++++++++++++++++++++++++---
> 1 file changed, 131 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/nvme/host/tcp.c b/drivers/nvme/host/tcp.c
> index ea67caf9d326..5cb46deb56e0 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 {
> @@ -232,10 +237,74 @@ static inline size_t nvme_tcp_pdu_last_send(struct nvme_tcp_request *req,
> #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)) {
> + 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;
Why is the offloaded = false needed here? you also clear it when
you setup.
> + 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, cpu_to_le16(req->status << 1), req->result))
> + nvme_complete_rq(rq);
Why is the status shifted here? it was taken from the cqe as is..
> +}
> +
> +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;
> +
> + req->offloaded = false;
> +
> + if (unlikely(!netdev)) {
> + pr_info_ratelimited("%s: netdev not found\n", __func__);
dev_info_ratelimited please.
> + 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)
> {
> @@ -377,6 +446,25 @@ bool nvme_tcp_resync_request(struct sock *sk, u32 seq, u32 flags)
>
> #else
>
> +static
> +int nvme_tcp_setup_ddp(struct nvme_tcp_queue *queue,
> + 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 void nvme_tcp_ddp_teardown_done(void *ddp_ctx)
> +{}
> +
> static
> int nvme_tcp_offload_socket(struct nvme_tcp_queue *queue)
> {
> @@ -665,6 +753,7 @@ 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);
> @@ -676,8 +765,15 @@ 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);
> + }
Maybe move this to nvme_tcp_complete_request as it is called from two
code paths.
> queue->nr_cqe++;
>
> return 0;
> @@ -871,9 +967,18 @@ 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,
> @@ -920,12 +1025,22 @@ 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);
> + if (test_bit(NVME_TCP_Q_OFF_DDP, &queue->flags)) {
> + if (queue->data_digest)
> + ret = skb_ddp_copy_and_hash_datagram_iter(skb, *offset,
> + &req->iter, recv_len, queue->rcv_hash);
> + else
> + ret = skb_ddp_copy_datagram_iter(skb, *offset,
> + &req->iter, recv_len);
> + } else {
> + 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);
> + }
> +
Maybe move this hunk to nvme_tcp_consume_skb or something?
> if (ret) {
> dev_err(queue->ctrl->ctrl.device,
> "queue %d failed to copy request %#x data",
> @@ -1149,6 +1264,7 @@ 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;
>
> @@ -1157,6 +1273,10 @@ 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));
>
> @@ -2464,6 +2584,7 @@ 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;
offloaded is being cleared lots of times, and I'm not clear what are
the lifetime rules here.
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