[PATCH 6/6] nvme: Add consistency check for zone count

[Matias Bjørling]

On 25/06/2020 14.21, Javier González wrote:
> From: Javier González <javier.gonz at samsung.com>
>
> Since the number of zones is calculated through the reported device
> capacity and the ZNS specification allows to report the total number of
> zones in the device, add an extra check to guarantee consistency between
> the device and the kernel.
>
> Signed-off-by: Javier González <javier.gonz at samsung.com>
> Signed-off-by: SelvaKumar S <selvakuma.s1 at samsung.com>
> Signed-off-by: Kanchan Joshi <joshi.k at samsung.com>
> Signed-off-by: Nitesh Shetty <nj.shetty at samsung.com>
> ---
>   drivers/nvme/host/zns.c | 7 +++++++
>   1 file changed, 7 insertions(+)
>
> diff --git a/drivers/nvme/host/zns.c b/drivers/nvme/host/zns.c
> index 7d8381fe7665..de806788a184 100644
> --- a/drivers/nvme/host/zns.c
> +++ b/drivers/nvme/host/zns.c
> @@ -234,6 +234,13 @@ static int nvme_ns_report_zones(struct nvme_ns *ns, sector_t sector,
>   		sector += ns->zsze * nz;
>   	}
>   
> +	if (nr_zones < 0 && zone_idx != ns->nr_zones) {
> +		dev_err(ns->ctrl->device, "inconsistent zone count %u/%u\n",
> +				zone_idx, ns->nr_zones);
> +		ret = -EINVAL;
> +		goto out_free;
> +	}
> +
>   	ret = zone_idx;
>   out_free:
>   	kvfree(report);

Sounds like a check for a broken implementation. For implementations in 
the wild that exhibits this behavior, a quirk can be added. This kind of 
check is generally not needed. This can easily be checked by having a 
test case in a validation suite. The kernel should not have to check for it.