Re: [PATCH v2 13/14] nvme-fc: Use CCR to recover controller that hits an error

Hannes Reinecke
2026-02-03T05:43:39Z

On 1/30/26 23:34, Mohamed Khalfella wrote:
> An alive nvme controller that hits an error now will move to FENCING
> state instead of RESETTING state. ctrl->fencing_work attempts CCR to
> terminate inflight IOs. If CCR succeeds, switch to FENCED -> RESETTING
> and continue error recovery as usual. If CCR fails, the behavior depends
> on whether the subsystem supports CQT or not. If CQT is not supported
> then reset the controller immediately as if CCR succeeded in order to
> maintain the current behavior. If CQT is supported switch to time-based
> recovery. Schedule ctrl->fenced_work resets the controller when time
> based recovery finishes.
>
> Either ctrl->err_work or ctrl->reset_work can run after a controller is
> fenced. Flush fencing work when either work run.
>
> Signed-off-by: Mohamed Khalfella <mkhalfella@purestorage.com>
> ---
> drivers/nvme/host/fc.c | 60 ++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 60 insertions(+)
>
> diff --git a/drivers/nvme/host/fc.c b/drivers/nvme/host/fc.c
> index f8f6071b78ed..3a01aeb39081 100644
> --- a/drivers/nvme/host/fc.c
> +++ b/drivers/nvme/host/fc.c
> @@ -166,6 +166,8 @@ struct nvme_fc_ctrl {
> struct blk_mq_tag_set admin_tag_set;
> struct blk_mq_tag_set tag_set;
>
> + struct work_struct fencing_work;
> + struct delayed_work fenced_work;
> struct work_struct ioerr_work;
> struct delayed_work connect_work;
>
> @@ -1866,12 +1868,59 @@ __nvme_fc_fcpop_chk_teardowns(struct nvme_fc_ctrl *ctrl,
> }
> }
>
> +static void nvme_fc_fenced_work(struct work_struct *work)
> +{
> + struct nvme_fc_ctrl *fc_ctrl = container_of(to_delayed_work(work),
> + struct nvme_fc_ctrl, fenced_work);
> + struct nvme_ctrl *ctrl = &fc_ctrl->ctrl;
> +
> + nvme_change_ctrl_state(ctrl, NVME_CTRL_FENCED);
> + if (nvme_change_ctrl_state(ctrl, NVME_CTRL_RESETTING))
> + queue_work(nvme_reset_wq, &fc_ctrl->ioerr_work);
> +}
> +
> +static void nvme_fc_fencing_work(struct work_struct *work)
> +{
> + struct nvme_fc_ctrl *fc_ctrl =
> + container_of(work, struct nvme_fc_ctrl, fencing_work);
> + struct nvme_ctrl *ctrl = &fc_ctrl->ctrl;
> + unsigned long rem;
> +
> + rem = nvme_fence_ctrl(ctrl);
> + if (!rem)
> + goto done;
> +
> + if (!ctrl->cqt) {
> + dev_info(ctrl->device,
> + "CCR failed, CQT not supported, skip time-based recovery\n");
> + goto done;
> + }
> +
> + dev_info(ctrl->device,
> + "CCR failed, switch to time-based recovery, timeout = %ums\n",
> + jiffies_to_msecs(rem));
> + queue_delayed_work(nvme_wq, &fc_ctrl->fenced_work, rem);
> + return;
> +

Same comments re fenced workqueue apply here.

> +done:
> + nvme_change_ctrl_state(ctrl, NVME_CTRL_FENCED);
> + if (nvme_change_ctrl_state(ctrl, NVME_CTRL_RESETTING))
> + queue_work(nvme_reset_wq, &fc_ctrl->ioerr_work);
> +}
> +
> +static void nvme_fc_flush_fencing_work(struct nvme_fc_ctrl *ctrl)
> +{
> + flush_work(&ctrl->fencing_work);
> + flush_delayed_work(&ctrl->fenced_work);
> +}
> +
> static void
> nvme_fc_ctrl_ioerr_work(struct work_struct *work)
> {
> struct nvme_fc_ctrl *ctrl =
> container_of(work, struct nvme_fc_ctrl, ioerr_work);
>
> + nvme_fc_flush_fencing_work(ctrl);
> nvme_fc_error_recovery(ctrl);
> }
>
> @@ -1896,6 +1945,14 @@ EXPORT_SYMBOL_GPL(nvme_fc_io_getuuid);
> static void nvme_fc_start_ioerr_recovery(struct nvme_fc_ctrl *ctrl,
> char *errmsg)
> {
> + if (nvme_change_ctrl_state(&ctrl->ctrl, NVME_CTRL_FENCING)) {
> + dev_warn(ctrl->ctrl.device,
> + "NVME-FC{%d}: starting controller fencing %s\n",
> + ctrl->cnum, errmsg);
> + queue_work(nvme_wq, &ctrl->fencing_work);
> + return;
> + }
> +
> if (!nvme_change_ctrl_state(&ctrl->ctrl, NVME_CTRL_RESETTING))
> return;
>
> @@ -3297,6 +3354,7 @@ nvme_fc_reset_ctrl_work(struct work_struct *work)
> struct nvme_fc_ctrl *ctrl =
> container_of(work, struct nvme_fc_ctrl, ctrl.reset_work);
>
> + nvme_fc_flush_fencing_work(ctrl);
> nvme_stop_ctrl(&ctrl->ctrl);
>
> /* will block will waiting for io to terminate */
> @@ -3471,6 +3529,8 @@ nvme_fc_alloc_ctrl(struct device *dev, struct nvmf_ctrl_options *opts,
>
> INIT_WORK(&ctrl->ctrl.reset_work, nvme_fc_reset_ctrl_work);
> INIT_DELAYED_WORK(&ctrl->connect_work, nvme_fc_connect_ctrl_work);
> + INIT_DELAYED_WORK(&ctrl->fenced_work, nvme_fc_fenced_work);
> + INIT_WORK(&ctrl->fencing_work, nvme_fc_fencing_work);
> INIT_WORK(&ctrl->ioerr_work, nvme_fc_ctrl_ioerr_work);
> spin_lock_init(&ctrl->lock);
>

And, of course, the same comments about sending CCR in response to a
KATO timeout and not a command timeout apply.

Cheers,

Hannes
--
Dr. Hannes Reinecke Kernel Storage Architect
hare@suse.de +49 911 74053 688
SUSE Software Solutions GmbH, Frankenstr. 146, 90461 Nürnberg
HRB 36809 (AG Nürnberg), GF: I. Totev, A. McDonald, W. Knoblich