[PATCH 12/13] nvme: let namespace probing continue for unsupported features

[Keith Busch]

On Thu, Apr 08, 2021 at 02:08:41PM +0200, Christoph Hellwig wrote:
> Instead of failing to scan the namespace entirely when unsupported
> features are detected, just mark the gendisk hidden but allow other
> access like the upcoming per-namespace character device.

This part looks fine for what it is, but I thought we were going even
further by allocating a namespace for the generic char device even if
its Command Set Indicator was unsupported by the kernel.
 
> Signed-off-by: Christoph Hellwig <hch at lst.de>
> ---
>  drivers/nvme/host/core.c | 11 ++++++++++-
>  drivers/nvme/host/zns.c  |  4 ++--
>  2 files changed, 12 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
> index 7ebe0225e01412..eba676b260b820 100644
> --- a/drivers/nvme/host/core.c
> +++ b/drivers/nvme/host/core.c
> @@ -1832,7 +1832,7 @@ static int nvme_update_ns_info(struct nvme_ns *ns, struct nvme_id_ns *id)
>  	if (blk_queue_is_zoned(ns->queue)) {
>  		ret = nvme_revalidate_zones(ns);
>  		if (ret && !nvme_first_scan(ns->disk))
> -			return ret;
> +			goto out;
>  	}
>  
>  	if (nvme_ns_head_multipath(ns->head)) {
> @@ -1847,6 +1847,15 @@ static int nvme_update_ns_info(struct nvme_ns *ns, struct nvme_id_ns *id)
>  
>  out_unfreeze:
>  	blk_mq_unfreeze_queue(ns->disk->queue);
> +out:
> +	/*
> +	 * If probing fails due an unsupported feature, hide the block device,
> +	 * but still allow other access.
> +	 */
> +	if (ret == -ENODEV) {
> +		ns->disk->flags |= GENHD_FL_HIDDEN;
> +		ret = 0;
> +	}
>  	return ret;
>  }
>  
> diff --git a/drivers/nvme/host/zns.c b/drivers/nvme/host/zns.c
> index bc2f344f0ae018..475dd45c3db49b 100644
> --- a/drivers/nvme/host/zns.c
> +++ b/drivers/nvme/host/zns.c
> @@ -96,7 +96,7 @@ int nvme_update_zone_info(struct nvme_ns *ns, unsigned lbaf)
>  		dev_warn(ns->ctrl->device,
>  			"zone operations:%x not supported for namespace:%u\n",
>  			le16_to_cpu(id->zoc), ns->head->ns_id);
> -		status = -EINVAL;
> +		status = -ENODEV;
>  		goto free_data;
>  	}
>  
> @@ -105,7 +105,7 @@ int nvme_update_zone_info(struct nvme_ns *ns, unsigned lbaf)
>  		dev_warn(ns->ctrl->device,
>  			"invalid zone size:%llu for namespace:%u\n",
>  			ns->zsze, ns->head->ns_id);
> -		status = -EINVAL;
> +		status = -ENODEV;
>  		goto free_data;
>  	}
>  
> --