Re: [RFC PATCH v5 07/27] nvme-tcp-offload: Add IO level implementation

Himanshu Madhani
2021-05-21T18:26:50Z

On 5/19/21 6:13 AM, Shai Malin wrote:
> From: Dean Balandin <dbalandin@marvell.com>
>
> In this patch, we present the IO level functionality.
> The nvme-tcp-offload shall work on the IO-level, meaning the
> nvme-tcp-offload ULP module shall pass the request to the nvme-tcp-offload
> vendor driver and shall expect for the request completion.
> No additional handling is needed in between, this design will reduce the
> CPU utilization as we will describe below.
>
> The nvme-tcp-offload vendor driver shall register to nvme-tcp-offload ULP
> with the following IO-path ops:
> - init_req
> - send_req - in order to pass the request to the handling of the offload
> driver that shall pass it to the vendor specific device
> - poll_queue
>
> The vendor driver will manage the context from which the request will be
> executed and the request aggregations.
> Once the IO completed, the nvme-tcp-offload vendor driver shall call
> command.done() that shall invoke the nvme-tcp-offload ULP layer for
> completing the request.
>
> This patch also contains initial definition of nvme_tcp_ofld_queue_rq().
>
> Acked-by: Igor Russkikh <irusskikh@marvell.com>
> Signed-off-by: Dean Balandin <dbalandin@marvell.com>
> Signed-off-by: Prabhakar Kushwaha <pkushwaha@marvell.com>
> Signed-off-by: Omkar Kulkarni <okulkarni@marvell.com>
> Signed-off-by: Michal Kalderon <mkalderon@marvell.com>
> Signed-off-by: Ariel Elior <aelior@marvell.com>
> Signed-off-by: Shai Malin <smalin@marvell.com>
> Reviewed-by: Hannes Reinecke <hare@suse.de>
> ---
> drivers/nvme/host/tcp-offload.c | 96 ++++++++++++++++++++++++++++++---
> 1 file changed, 88 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/nvme/host/tcp-offload.c b/drivers/nvme/host/tcp-offload.c
> index 8ed7668d987a..276b8475ac85 100644
> --- a/drivers/nvme/host/tcp-offload.c
> +++ b/drivers/nvme/host/tcp-offload.c
> @@ -127,7 +127,10 @@ void nvme_tcp_ofld_req_done(struct nvme_tcp_ofld_req *req,
> union nvme_result *result,
> __le16 status)
> {
> - /* Placeholder - complete request with/without error */
> + struct request *rq = blk_mq_rq_from_pdu(req);
> +
> + if (!nvme_try_complete_req(rq, cpu_to_le16(status << 1), *result))
> + nvme_complete_rq(rq);
> }
>
> struct nvme_tcp_ofld_dev *
> @@ -700,6 +703,34 @@ static void nvme_tcp_ofld_free_ctrl(struct nvme_ctrl *nctrl)
> kfree(ctrl);
> }
>
> +static void nvme_tcp_ofld_set_sg_null(struct nvme_command *c)
> +{
> + struct nvme_sgl_desc *sg = &c->common.dptr.sgl;
> +
> + sg->addr = 0;
> + sg->length = 0;
> + sg->type = (NVME_TRANSPORT_SGL_DATA_DESC << 4) | NVME_SGL_FMT_TRANSPORT_A;
> +}
> +
> +inline void nvme_tcp_ofld_set_sg_inline(struct nvme_tcp_ofld_queue *queue,
> + struct nvme_command *c, u32 data_len)
> +{
> + struct nvme_sgl_desc *sg = &c->common.dptr.sgl;
> +
> + sg->addr = cpu_to_le64(queue->ctrl->nctrl.icdoff);
> + sg->length = cpu_to_le32(data_len);
> + sg->type = (NVME_SGL_FMT_DATA_DESC << 4) | NVME_SGL_FMT_OFFSET;
> +}
> +
> +void nvme_tcp_ofld_map_data(struct nvme_command *c, u32 data_len)
> +{
> + struct nvme_sgl_desc *sg = &c->common.dptr.sgl;
> +
> + sg->addr = 0;
> + sg->length = cpu_to_le32(data_len);
> + sg->type = (NVME_TRANSPORT_SGL_DATA_DESC << 4) | NVME_SGL_FMT_TRANSPORT_A;
> +}
> +
> static void nvme_tcp_ofld_submit_async_event(struct nvme_ctrl *arg)
> {
> /* Placeholder - submit_async_event */
> @@ -855,9 +886,12 @@ nvme_tcp_ofld_init_request(struct blk_mq_tag_set *set,
> {
> struct nvme_tcp_ofld_req *req = blk_mq_rq_to_pdu(rq);
> struct nvme_tcp_ofld_ctrl *ctrl = set->driver_data;
> + int qid;
>
> - /* Placeholder - init request */
> -
> + qid = (set == &ctrl->tag_set) ? hctx_idx + 1 : 0;
> + req->queue = &ctrl->queues[qid];
> + nvme_req(rq)->ctrl = &ctrl->nctrl;
> + nvme_req(rq)->cmd = &req->nvme_cmd;
> req->done = nvme_tcp_ofld_req_done;
> ctrl->dev->ops->init_req(req);
>
> @@ -872,16 +906,60 @@ EXPORT_SYMBOL_GPL(nvme_tcp_ofld_inline_data_size);
>
> static void nvme_tcp_ofld_commit_rqs(struct blk_mq_hw_ctx *hctx)
> {
> - /* Call ops->commit_rqs */
> + struct nvme_tcp_ofld_queue *queue = hctx->driver_data;
> + struct nvme_tcp_ofld_dev *dev = queue->dev;
> + struct nvme_tcp_ofld_ops *ops = dev->ops;
> +
> + ops->commit_rqs(queue);
> }
>
> static blk_status_t
> nvme_tcp_ofld_queue_rq(struct blk_mq_hw_ctx *hctx,
> const struct blk_mq_queue_data *bd)
> {
> - /* Call nvme_setup_cmd(...) */
> + struct nvme_tcp_ofld_req *req = blk_mq_rq_to_pdu(bd->rq);
> + struct nvme_tcp_ofld_queue *queue = hctx->driver_data;
> + struct nvme_tcp_ofld_ctrl *ctrl = queue->ctrl;
> + struct nvme_ns *ns = hctx->queue->queuedata;
> + struct nvme_tcp_ofld_dev *dev = queue->dev;
> + struct nvme_tcp_ofld_ops *ops = dev->ops;
> + struct nvme_command *nvme_cmd;
> + struct request *rq;
> + bool queue_ready;
> + u32 data_len;
> + int rc;
> +
> + queue_ready = test_bit(NVME_TCP_OFLD_Q_LIVE, &queue->flags);
> +
> + req->rq = bd->rq;
> + req->async = false;
> + rq = req->rq;
> +
> + if (!nvme_check_ready(&ctrl->nctrl, req->rq, queue_ready))
> + return nvme_fail_nonready_command(&ctrl->nctrl, req->rq);
> +
> + rc = nvme_setup_cmd(ns, req->rq);
> + if (unlikely(rc))
> + return rc;
>
> - /* Call ops->send_req(...) */
> + blk_mq_start_request(req->rq);
> + req->last = bd->last;
> +
> + nvme_cmd = &req->nvme_cmd;
> + nvme_cmd->common.flags |= NVME_CMD_SGL_METABUF;
> +
> + data_len = blk_rq_nr_phys_segments(rq) ? blk_rq_payload_bytes(rq) : 0;
> + if (!data_len)
> + nvme_tcp_ofld_set_sg_null(&req->nvme_cmd);
> + else if ((rq_data_dir(rq) == WRITE) &&
> + data_len <= nvme_tcp_ofld_inline_data_size(queue))
> + nvme_tcp_ofld_set_sg_inline(queue, nvme_cmd, data_len);
> + else
> + nvme_tcp_ofld_map_data(nvme_cmd, data_len);
> +
> + rc = ops->send_req(req);
> + if (unlikely(rc))
> + return rc;
>
> return BLK_STS_OK;
> }
> @@ -954,9 +1032,11 @@ static int nvme_tcp_ofld_map_queues(struct blk_mq_tag_set *set)
>
> static int nvme_tcp_ofld_poll(struct blk_mq_hw_ctx *hctx)
> {
> - /* Placeholder - Implement polling mechanism */
> + struct nvme_tcp_ofld_queue *queue = hctx->driver_data;
> + struct nvme_tcp_ofld_dev *dev = queue->dev;
> + struct nvme_tcp_ofld_ops *ops = dev->ops;
>
> - return 0;
> + return ops->poll_queue(queue);
> }
>
> static struct blk_mq_ops nvme_tcp_ofld_mq_ops = {
>

Reviewed-by: Himanshu Madhani <himanshu.madhani@oracle.com>

--
Himanshu Madhani Oracle Linux Engineering