[PATCH v3 07/21] nvme: Introduce FENCING and FENCED controller states

[Mohamed Khalfella <mkhalfella@purestorage.com>]

FENCING is a new controller state that a LIVE controller enter when an
error is encountered. While in FENCING state,inflight IOs that timeout
are not canceled because they should be held until either CCR succeeds
or time-based recovery completes. While the queues remain alive requests
are not allowed to be sent in this state and the controller cannot be
reset or deleted. This is intentional because resetting or deleting the
controller results in canceling inflight IOs.

FENCED is a short-term state the controller enters before it is reset.
It exists only to prevent manual resets from happening while controller
is in FENCING state.

Signed-off-by: Mohamed Khalfella <mkhalfella@purestorage.com>
---
 drivers/nvme/host/core.c  | 27 +++++++++++++++++++++++++--
 drivers/nvme/host/nvme.h  |  4 ++++
 drivers/nvme/host/sysfs.c |  2 ++
 3 files changed, 31 insertions(+), 2 deletions(-)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index 8d26e27992fc..231d402e9bfb 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -574,10 +574,29 @@ bool nvme_change_ctrl_state(struct nvme_ctrl *ctrl,
 			break;
 		}
 		break;
+	case NVME_CTRL_FENCING:
+		switch (old_state) {
+		case NVME_CTRL_LIVE:
+			changed = true;
+			fallthrough;
+		default:
+			break;
+		}
+		break;
+	case NVME_CTRL_FENCED:
+		switch (old_state) {
+		case NVME_CTRL_FENCING:
+			changed = true;
+			fallthrough;
+		default:
+			break;
+		}
+		break;
 	case NVME_CTRL_RESETTING:
 		switch (old_state) {
 		case NVME_CTRL_NEW:
 		case NVME_CTRL_LIVE:
+		case NVME_CTRL_FENCED:
 			changed = true;
 			fallthrough;
 		default:
@@ -760,6 +779,8 @@ blk_status_t nvme_fail_nonready_command(struct nvme_ctrl *ctrl,
 
 	if (state != NVME_CTRL_DELETING_NOIO &&
 	    state != NVME_CTRL_DELETING &&
+	    state != NVME_CTRL_FENCING &&
+	    state != NVME_CTRL_FENCED &&
 	    state != NVME_CTRL_DEAD &&
 	    !test_bit(NVME_CTRL_FAILFAST_EXPIRED, &ctrl->flags) &&
 	    !blk_noretry_request(rq) && !(rq->cmd_flags & REQ_NVME_MPATH))
@@ -802,10 +823,12 @@ bool __nvme_check_ready(struct nvme_ctrl *ctrl, struct request *rq,
 			     req->cmd->fabrics.fctype == nvme_fabrics_type_auth_receive))
 				return true;
 			break;
-		default:
-			break;
+		case NVME_CTRL_FENCING:
+		case NVME_CTRL_FENCED:
 		case NVME_CTRL_DEAD:
 			return false;
+		default:
+			break;
 		}
 	}
 
diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
index 6984950b9aa8..b1c37eb3379e 100644
--- a/drivers/nvme/host/nvme.h
+++ b/drivers/nvme/host/nvme.h
@@ -251,6 +251,8 @@ static inline u16 nvme_req_qid(struct request *req)
 enum nvme_ctrl_state {
 	NVME_CTRL_NEW,
 	NVME_CTRL_LIVE,
+	NVME_CTRL_FENCING,
+	NVME_CTRL_FENCED,
 	NVME_CTRL_RESETTING,
 	NVME_CTRL_CONNECTING,
 	NVME_CTRL_DELETING,
@@ -776,6 +778,8 @@ static inline bool nvme_state_terminal(struct nvme_ctrl *ctrl)
 	switch (nvme_ctrl_state(ctrl)) {
 	case NVME_CTRL_NEW:
 	case NVME_CTRL_LIVE:
+	case NVME_CTRL_FENCING:
+	case NVME_CTRL_FENCED:
 	case NVME_CTRL_RESETTING:
 	case NVME_CTRL_CONNECTING:
 		return false;
diff --git a/drivers/nvme/host/sysfs.c b/drivers/nvme/host/sysfs.c
index cd835dd2377f..1e4261144933 100644
--- a/drivers/nvme/host/sysfs.c
+++ b/drivers/nvme/host/sysfs.c
@@ -443,6 +443,8 @@ static ssize_t nvme_sysfs_show_state(struct device *dev,
 	static const char *const state_name[] = {
 		[NVME_CTRL_NEW]		= "new",
 		[NVME_CTRL_LIVE]	= "live",
+		[NVME_CTRL_FENCING]	= "fencing",
+		[NVME_CTRL_FENCED]	= "fenced",
 		[NVME_CTRL_RESETTING]	= "resetting",
 		[NVME_CTRL_CONNECTING]	= "connecting",
 		[NVME_CTRL_DELETING]	= "deleting",
-- 
2.52.0