nvmet: support for traffic based keep-alive

A controller that supports traffic based keep-alive can restart the keep
alive timer even when no keep-alive was not received in the kato period
as long as other admin or I/O commands were received.  For each command
set ctrl->cmd_seen to true, and when keep-alive timer expires, if any
commands were seen, resched ka_work instead of escalating to a fatal
error.
Signed-off-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

drivers/nvme/target/admin-cmd.c

@@ -304,7 +304,8 @@ static void nvmet_execute_identify_ctrl(struct nvmet_req *req)
 
 	/* XXX: figure out what to do about RTD3R/RTD3 */
 	id->oaes = cpu_to_le32(NVMET_AEN_CFG_OPTIONAL);
-	id->ctratt = cpu_to_le32(NVME_CTRL_ATTR_HID_128_BIT);
+	id->ctratt = cpu_to_le32(NVME_CTRL_ATTR_HID_128_BIT |
+		NVME_CTRL_ATTR_TBKAS);
 
 	id->oacs = 0;
 

drivers/nvme/target/core.c

@@ -299,6 +299,15 @@ static void nvmet_keep_alive_timer(struct work_struct *work)
 {
 	struct nvmet_ctrl *ctrl = container_of(to_delayed_work(work),
 			struct nvmet_ctrl, ka_work);
+	bool cmd_seen = ctrl->cmd_seen;
+
+	ctrl->cmd_seen = false;
+	if (cmd_seen) {
+		pr_debug("ctrl %d reschedule traffic based keep-alive timer\n",
+			ctrl->cntlid);
+		schedule_delayed_work(&ctrl->ka_work, ctrl->kato * HZ);
+		return;
+	}
 
 	pr_err("ctrl %d keep-alive timer (%d seconds) expired!\n",
 		ctrl->cntlid, ctrl->kato);
@@ -801,6 +810,9 @@ bool nvmet_req_init(struct nvmet_req *req, struct nvmet_cq *cq,
 		goto fail;
 	}
 
+	if (sq->ctrl)
+		sq->ctrl->cmd_seen = true;
+
 	return true;
 
 fail:

drivers/nvme/target/nvmet.h

@@ -163,6 +163,8 @@ struct nvmet_ctrl {
 	struct nvmet_cq		**cqs;
 	struct nvmet_sq		**sqs;
 
+	bool			cmd_seen;
+
 	struct mutex		lock;
 	u64			cap;
 	u32			cc;