From: Sagi Grimberg <sagi@grimberg.me>
Date: Fri, 2 Nov 2018 10:28:15 -0700
Subject: [PATCH] nvme: support traffic based keep-alive
Git-commit: 6e3ca03ee934572d5de4fb2224c01e12c4d422c8
Patch-mainline: v5.0-rc1
References: bsc#1104967,FATE#325924

If the controller supports traffic based keep alive, we restart the keep
alive timer if any admin or io commands was completed during the kato
period.  This prevents a possible starvation of keep alive commands in
the presence of heavy traffic as in such case, we already have a health
indication from the host perspective.

Only set a comp_seen indicator in case the controller supports keep
alive to minimize the overhead for pci controllers.

Signed-off-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Acked-by: Hannes Reinecke <hare@suse.com>
---
 drivers/nvme/host/core.c | 13 +++++++++++++
 drivers/nvme/host/nvme.h |  1 +
 include/linux/nvme.h     |  1 +
 3 files changed, 15 insertions(+)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index 9de6244a345c..48ffb1d685c2 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -251,6 +251,9 @@ void nvme_complete_rq(struct request *req)
 
 	trace_nvme_complete_rq(req);
 
+	if (nvme_req(req)->ctrl->kas)
+		nvme_req(req)->ctrl->comp_seen = true;
+
 	if (unlikely(status != BLK_STS_OK && nvme_req_needs_retry(req))) {
 		if ((req->cmd_flags & REQ_NVME_MPATH) &&
 		    blk_path_error(status)) {
@@ -839,6 +842,7 @@ static void nvme_keep_alive_end_io(struct request *rq, blk_status_t status)
 		return;
 	}
 
+	ctrl->comp_seen = false;
 	spin_lock_irqsave(&ctrl->lock, flags);
 	if (ctrl->state == NVME_CTRL_LIVE ||
 	    ctrl->state == NVME_CTRL_CONNECTING)
@@ -863,6 +867,15 @@ static void nvme_keep_alive_work(struct work_struct *work)
 {
 	struct nvme_ctrl *ctrl = container_of(to_delayed_work(work),
 			struct nvme_ctrl, ka_work);
+	bool comp_seen = ctrl->comp_seen;
+
+	if ((ctrl->ctratt & NVME_CTRL_ATTR_TBKAS) && comp_seen) {
+		dev_dbg(ctrl->device,
+			"reschedule traffic based keep-alive timer\n");
+		ctrl->comp_seen = false;
+		schedule_delayed_work(&ctrl->ka_work, ctrl->kato * HZ);
+		return;
+	}
 
 	if (nvme_keep_alive(ctrl)) {
 		/* allocation failure, reset the controller */
diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
index 4be7bbcfe66d..f2594d468f29 100644
--- a/drivers/nvme/host/nvme.h
+++ b/drivers/nvme/host/nvme.h
@@ -145,6 +145,7 @@ enum nvme_ctrl_state {
 };
 
 struct nvme_ctrl {
+	bool comp_seen;
 	enum nvme_ctrl_state state;
 	bool identified;
 	spinlock_t lock;
diff --git a/include/linux/nvme.h b/include/linux/nvme.h
index 753c83a5c01f..429c4cf90899 100644
--- a/include/linux/nvme.h
+++ b/include/linux/nvme.h
@@ -200,6 +200,7 @@ enum {
 
 enum nvme_ctrl_attr {
 	NVME_CTRL_ATTR_HID_128_BIT	= (1 << 0),
+	NVME_CTRL_ATTR_TBKAS		= (1 << 6),
 };
 
 struct nvme_id_ctrl {
-- 
2.16.4