linux-kernel - [PATCH 1/2] nvmet: introduce transport layer keep-alive

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Date:   Tue, 27 Oct 2020 20:15:45 +0800
From:   zhenwei pi <pizhenwei@...edance.com>
To:     hch@....de, sagi@...mberg.me, chaitanya.kulkarni@....com
Cc:     pizhenwei@...edance.com, linux-nvme@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH 1/2] nvmet: introduce transport layer keep-alive

In the zero KATO scenario, if initiator crashes without transport
layer disconnection, target side would never reclaim resources.

A target could start transport layer keep-alive to detect dead
connection for the admin queue.

Signed-off-by: zhenwei pi <pizhenwei@...edance.com>
---
 drivers/nvme/target/admin-cmd.c |  2 +-
 drivers/nvme/target/core.c      | 14 +++++++++++---
 drivers/nvme/target/nvmet.h     |  3 ++-
 3 files changed, 14 insertions(+), 5 deletions(-)

diff --git a/drivers/nvme/target/admin-cmd.c b/drivers/nvme/target/admin-cmd.c
index dca34489a1dc..53fbd5c193a1 100644
--- a/drivers/nvme/target/admin-cmd.c
+++ b/drivers/nvme/target/admin-cmd.c
@@ -729,7 +729,7 @@ u16 nvmet_set_feat_kato(struct nvmet_req *req)
 
 	nvmet_stop_keep_alive_timer(req->sq->ctrl);
 	req->sq->ctrl->kato = DIV_ROUND_UP(val32, 1000);
-	nvmet_start_keep_alive_timer(req->sq->ctrl);
+	nvmet_start_keep_alive_timer(req->sq->ctrl, req);
 
 	nvmet_set_result(req, req->sq->ctrl->kato);
 
diff --git a/drivers/nvme/target/core.c b/drivers/nvme/target/core.c
index 957b39a82431..451192f7ad6a 100644
--- a/drivers/nvme/target/core.c
+++ b/drivers/nvme/target/core.c
@@ -395,10 +395,18 @@ static void nvmet_keep_alive_timer(struct work_struct *work)
 	nvmet_ctrl_fatal_error(ctrl);
 }
 
-void nvmet_start_keep_alive_timer(struct nvmet_ctrl *ctrl)
+void nvmet_start_keep_alive_timer(struct nvmet_ctrl *ctrl, struct nvmet_req *req)
 {
-	if (unlikely(ctrl->kato == 0))
+	if (unlikely(ctrl->kato == 0)) {
+		if (req->ops->keep_alive)
+			pr_info("ctrl %d starts with transport keep-alive %s\n", ctrl->cntlid,
+				req->ops->keep_alive(req) ? "failed" : "succeed");
+		else
+			pr_info("ctrl %d starts without both NVMeOF and transport keep-alive",
+				ctrl->cntlid);
+
 		return;
+	}
 
 	pr_debug("ctrl %d start keep-alive timer for %d secs\n",
 		ctrl->cntlid, ctrl->kato);
@@ -1383,7 +1391,7 @@ u16 nvmet_alloc_ctrl(const char *subsysnqn, const char *hostnqn,
 	ctrl->err_counter = 0;
 	spin_lock_init(&ctrl->error_lock);
 
-	nvmet_start_keep_alive_timer(ctrl);
+	nvmet_start_keep_alive_timer(ctrl, req);
 
 	mutex_lock(&subsys->lock);
 	list_add_tail(&ctrl->subsys_entry, &subsys->ctrls);
diff --git a/drivers/nvme/target/nvmet.h b/drivers/nvme/target/nvmet.h
index 559a15ccc322..de1785ce9fcd 100644
--- a/drivers/nvme/target/nvmet.h
+++ b/drivers/nvme/target/nvmet.h
@@ -305,6 +305,7 @@ struct nvmet_fabrics_ops {
 	u16 (*install_queue)(struct nvmet_sq *nvme_sq);
 	void (*discovery_chg)(struct nvmet_port *port);
 	u8 (*get_mdts)(const struct nvmet_ctrl *ctrl);
+	int (*keep_alive)(struct nvmet_req *req);
 };
 
 #define NVMET_MAX_INLINE_BIOVEC	8
@@ -395,7 +396,7 @@ void nvmet_get_feat_async_event(struct nvmet_req *req);
 u16 nvmet_set_feat_kato(struct nvmet_req *req);
 u16 nvmet_set_feat_async_event(struct nvmet_req *req, u32 mask);
 void nvmet_execute_async_event(struct nvmet_req *req);
-void nvmet_start_keep_alive_timer(struct nvmet_ctrl *ctrl);
+void nvmet_start_keep_alive_timer(struct nvmet_ctrl *ctrl, struct nvmet_req *req);
 void nvmet_stop_keep_alive_timer(struct nvmet_ctrl *ctrl);
 
 u16 nvmet_parse_connect_cmd(struct nvmet_req *req);
-- 
2.11.0