[RFC PATCH v3 07/11] nvme-tcp-offload: Add IO level implementation

Shai Malin
2021-02-07T18:14:25Z

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 compilation.
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
- map_sg - in order to map the request sg (similar to nvme_rdma_map_data)
- 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.

Signed-off-by: Dean Balandin <dbalandin@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>
---
drivers/nvme/host/tcp-offload.c | 82 ++++++++++++++++++++++++++++++---
1 file changed, 75 insertions(+), 7 deletions(-)

diff --git a/drivers/nvme/host/tcp-offload.c b/drivers/nvme/host/tcp-offload.c
index f1023f2eae8d..bf64551c7a91 100644
--- a/drivers/nvme/host/tcp-offload.c
+++ b/drivers/nvme/host/tcp-offload.c
@@ -113,6 +113,7 @@ int nvme_tcp_ofld_report_queue_err(struct nvme_tcp_ofld_queue *queue)
/**
* nvme_tcp_ofld_req_done() - NVMeTCP Offload request done callback
* function. Pointed to by nvme_tcp_ofld_req->done.
+ * Handles both NVME_TCP_F_DATA_SUCCESS flag and NVMe CQE.
* @req: NVMeTCP offload request to complete.
* @result: The nvme_result.
* @status: The completion status.
@@ -125,7 +126,10 @@ 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 *
@@ -754,9 +758,10 @@ 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 = (set == &ctrl->tag_set) ? hctx_idx + 1 : 0;

- /* Placeholder - init request */
-
+ req->queue = &ctrl->queues[qid];
+ nvme_req(rq)->ctrl = &ctrl->nctrl;
req->done = nvme_tcp_ofld_req_done;
ctrl->dev->ops->init_req(req);

@@ -767,9 +772,32 @@ 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 request *rq = bd->rq;
+ bool queue_ready;
+ int rc;
+
+ queue_ready = test_bit(NVME_TCP_OFLD_Q_LIVE, &queue->flags);
+ if (!nvmf_check_ready(&ctrl->nctrl, rq, queue_ready))
+ return nvmf_fail_nonready_command(&ctrl->nctrl, rq);
+
+ rc = nvme_setup_cmd(ns, rq, &req->nvme_cmd);
+ if (unlikely(rc))
+ return rc;
+
+ blk_mq_start_request(rq);
+ rc = ops->map_sg(dev, req);
+ if (unlikely(rc))
+ return rc;

- /* Call ops->map_sg(...) */
+ rc = ops->send_req(req);
+ if (unlikely(rc))
+ return rc;

return BLK_STS_OK;
}
@@ -839,9 +867,47 @@ 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 enum blk_eh_timer_return
+nvme_tcp_ofld_timeout(struct request *rq, bool reserved)
+{
+ struct nvme_tcp_ofld_req *req = blk_mq_rq_to_pdu(rq);
+ struct nvme_tcp_ofld_ctrl *ctrl = req->queue->ctrl;
+
+ /* Restart the timer if a controller reset is already scheduled. Any
+ * timed out request would be handled before entering the connecting
+ * state.
+ */
+ if (ctrl->nctrl.state == NVME_CTRL_RESETTING)
+ return BLK_EH_RESET_TIMER;
+
+ dev_warn(ctrl->nctrl.device,
+ "queue %d: timeout request %#x type %d\n",
+ nvme_tcp_ofld_qid(req->queue), rq->tag,
+ req->nvme_cmd.common.opcode);
+
+ if (ctrl->nctrl.state != NVME_CTRL_LIVE) {
+ /*
+ * Teardown immediately if controller times out while starting
+ * or we are already started error recovery. all outstanding
+ * requests are completed on shutdown, so we return BLK_EH_DONE.
+ */
+ flush_work(&ctrl->err_work);
+ nvme_tcp_ofld_teardown_io_queues(&ctrl->nctrl, false);
+ nvme_tcp_ofld_teardown_admin_queue(&ctrl->nctrl, false);
+ return BLK_EH_DONE;
+ }
+
+ dev_warn(ctrl->nctrl.device, "starting error recovery\n");
+ nvme_tcp_ofld_error_recovery(&ctrl->nctrl);
+
+ return BLK_EH_RESET_TIMER;
}

static struct blk_mq_ops nvme_tcp_ofld_mq_ops = {
@@ -851,6 +917,7 @@ static struct blk_mq_ops nvme_tcp_ofld_mq_ops = {
.exit_request = nvme_tcp_ofld_exit_request,
.init_hctx = nvme_tcp_ofld_init_hctx,
.map_queues = nvme_tcp_ofld_map_queues,
+ .timeout = nvme_tcp_ofld_timeout,
.poll = nvme_tcp_ofld_poll,
};

@@ -860,6 +927,7 @@ static struct blk_mq_ops nvme_tcp_ofld_admin_mq_ops = {
.complete = nvme_complete_rq,
.exit_request = nvme_tcp_ofld_exit_request,
.init_hctx = nvme_tcp_ofld_init_hctx,
+ .timeout = nvme_tcp_ofld_timeout,
};

static const struct nvme_ctrl_ops nvme_tcp_ofld_ctrl_ops = {