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

[Sagi Grimberg]

On 10/27/20 5:15 AM, zhenwei pi wrote:

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.

Not sure why we should worry about kato=0, it's really
more for debug purposes. I'd rather that we block this
option from the host altogether.

Signed-off-by: zhenwei pi <pizhen...@bytedance.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);