[PATCH v6 2/6] nvme-fc: marginal path handling

[John Meneghini]

Reviewed-by: John Meneghini <jmeneghi at redhat.com>

On 6/20/25 1:56 PM, Bryan Gurney wrote:
> From: Hannes Reinecke <hare at kernel.org>
> 
> FPIN LI (link integrity) messages are received when the attached
> fabric detects hardware errors. In response to these messages I/O
> should be directed away from the affected ports, and only used
> if the 'optimized' paths are unavailable.
> To handle this a new controller flag 'NVME_CTRL_MARGINAL' is added
> which will cause the multipath scheduler to skip these paths when
> checking for 'optimized' paths. They are, however, still eligible
> for non-optimized path selected. The flag is cleared upon reset as then the
> faulty hardware might be replaced.
> 
> Signed-off-by: Hannes Reinecke <hare at kernel.org>
> Tested-by: Bryan Gurney <bgurney at redhat.com>
> ---
>   drivers/nvme/host/core.c      |  1 +
>   drivers/nvme/host/fc.c        |  4 ++++
>   drivers/nvme/host/multipath.c | 17 +++++++++++------
>   drivers/nvme/host/nvme.h      |  6 ++++++
>   4 files changed, 22 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
> index 3da5ac71a9b0..ac03ef7baab9 100644
> --- a/drivers/nvme/host/core.c
> +++ b/drivers/nvme/host/core.c
> @@ -5040,6 +5040,7 @@ int nvme_init_ctrl(struct nvme_ctrl *ctrl, struct device *dev,
>   	WRITE_ONCE(ctrl->state, NVME_CTRL_NEW);
>   	ctrl->passthru_err_log_enabled = false;
>   	clear_bit(NVME_CTRL_FAILFAST_EXPIRED, &ctrl->flags);
> +	clear_bit(NVME_CTRL_MARGINAL, &ctrl->flags);
>   	spin_lock_init(&ctrl->lock);
>   	mutex_init(&ctrl->namespaces_lock);
>   
> diff --git a/drivers/nvme/host/fc.c b/drivers/nvme/host/fc.c
> index 014b387f1e8b..7e81c815bb83 100644
> --- a/drivers/nvme/host/fc.c
> +++ b/drivers/nvme/host/fc.c
> @@ -786,6 +786,10 @@ nvme_fc_ctrl_connectivity_loss(struct nvme_fc_ctrl *ctrl)
>   		"Reconnect", ctrl->cnum);
>   
>   	set_bit(ASSOC_FAILED, &ctrl->flags);
> +
> +	/* clear 'marginal' flag as controller will be reset */
> +	clear_bit(NVME_CTRL_MARGINAL, &ctrl->flags);
> +
>   	nvme_reset_ctrl(&ctrl->ctrl);
>   }
>   
> diff --git a/drivers/nvme/host/multipath.c b/drivers/nvme/host/multipath.c
> index 1062467595f3..003954985675 100644
> --- a/drivers/nvme/host/multipath.c
> +++ b/drivers/nvme/host/multipath.c
> @@ -324,11 +324,14 @@ static struct nvme_ns *__nvme_find_path(struct nvme_ns_head *head, int node)
>   
>   		switch (ns->ana_state) {
>   		case NVME_ANA_OPTIMIZED:
> -			if (distance < found_distance) {
> -				found_distance = distance;
> -				found = ns;
> +			if (!nvme_ctrl_is_marginal(ns->ctrl)) {
> +				if (distance < found_distance) {
> +					found_distance = distance;
> +					found = ns;
> +				}
> +				break;
>   			}
> -			break;
> +			fallthrough;
>   		case NVME_ANA_NONOPTIMIZED:
>   			if (distance < fallback_distance) {
>   				fallback_distance = distance;
> @@ -381,7 +384,8 @@ static struct nvme_ns *nvme_round_robin_path(struct nvme_ns_head *head)
>   
>   		if (ns->ana_state == NVME_ANA_OPTIMIZED) {
>   			found = ns;
> -			goto out;
> +			if (!nvme_ctrl_is_marginal(ns->ctrl))
> +				goto out;
>   		}
>   		if (ns->ana_state == NVME_ANA_NONOPTIMIZED)
>   			found = ns;
> @@ -445,7 +449,8 @@ static struct nvme_ns *nvme_queue_depth_path(struct nvme_ns_head *head)
>   static inline bool nvme_path_is_optimized(struct nvme_ns *ns)
>   {
>   	return nvme_ctrl_state(ns->ctrl) == NVME_CTRL_LIVE &&
> -		ns->ana_state == NVME_ANA_OPTIMIZED;
> +		ns->ana_state == NVME_ANA_OPTIMIZED &&
> +		!nvme_ctrl_is_marginal(ns->ctrl);
>   }
>   
>   static struct nvme_ns *nvme_numa_path(struct nvme_ns_head *head)
> diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
> index 7df2ea21851f..71a5c5f87db6 100644
> --- a/drivers/nvme/host/nvme.h
> +++ b/drivers/nvme/host/nvme.h
> @@ -275,6 +275,7 @@ enum nvme_ctrl_flags {
>   	NVME_CTRL_SKIP_ID_CNS_CS	= 4,
>   	NVME_CTRL_DIRTY_CAPABILITY	= 5,
>   	NVME_CTRL_FROZEN		= 6,
> +	NVME_CTRL_MARGINAL		= 7,
>   };
>   
>   struct nvme_ctrl {
> @@ -417,6 +418,11 @@ static inline enum nvme_ctrl_state nvme_ctrl_state(struct nvme_ctrl *ctrl)
>   	return READ_ONCE(ctrl->state);
>   }
>   
> +static inline bool nvme_ctrl_is_marginal(struct nvme_ctrl *ctrl)
> +{
> +	return test_bit(NVME_CTRL_MARGINAL, &ctrl->flags);
> +}
> +
>   enum nvme_iopolicy {
>   	NVME_IOPOLICY_NUMA,
>   	NVME_IOPOLICY_RR,