[PATCH v2 07/14] nvme: Introduce FENCING and FENCED controller states

Mohamed Khalfella
2026-01-30T22:36:31Z

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 can not be
reset of 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 to happen while controller is
in FENCING state.

Signed-off-by: Mohamed Khalfella <mkhalfella@purestorage.com>
---
drivers/nvme/host/core.c | 25 +++++++++++++++++++++++--
drivers/nvme/host/nvme.h | 4 ++++
drivers/nvme/host/sysfs.c | 2 ++
3 files changed, 29 insertions(+), 2 deletions(-)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index 8961d612ccb0..3e1e02822dd4 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 +779,7 @@ 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_DEAD &&
!test_bit(NVME_CTRL_FAILFAST_EXPIRED, &ctrl->flags) &&
!blk_noretry_request(rq) && !(rq->cmd_flags & REQ_NVME_MPATH))
@@ -802,10 +822,11 @@ 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_DEAD:
return false;
+ default:
+ break;
}
}

diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
index 9dd9f179ad88..00866bbc66f3 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,
@@ -777,6 +779,8 @@ 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 f81bbb6ec768..4ec9dfeb736e 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