Re: [PATCH 1/6] nvme: zns: Allow ZNS drives that have non-power_of_2 zone size

[Damien Le Moal <damien.lemoal@opensource.wdc.com>]

On 3/9/22 01:53, Pankaj Raghav wrote:
> Remove the condition which disallows non-power_of_2 zone size ZNS drive
> to be updated and use generic method to calculate number of zones
> instead of relying on log and shift based calculation on zone size.
> 
> Signed-off-by: Pankaj Raghav <p.raghav@samsung.com>
> ---
>  drivers/nvme/host/zns.c | 9 +--------
>  1 file changed, 1 insertion(+), 8 deletions(-)
> 
> diff --git a/drivers/nvme/host/zns.c b/drivers/nvme/host/zns.c
> index 9f81beb4df4e..ad02c61c0b52 100644
> --- a/drivers/nvme/host/zns.c
> +++ b/drivers/nvme/host/zns.c
> @@ -101,13 +101,6 @@ int nvme_update_zone_info(struct nvme_ns *ns, unsigned lbaf)
>  	}
>  
>  	ns->zsze = nvme_lba_to_sect(ns, le64_to_cpu(id->lbafe[lbaf].zsze));
> -	if (!is_power_of_2(ns->zsze)) {
> -		dev_warn(ns->ctrl->device,
> -			"invalid zone size:%llu for namespace:%u\n",
> -			ns->zsze, ns->head->ns_id);
> -		status = -ENODEV;
> -		goto free_data;
> -	}

Doing this will allow a non power of 2 zone sized device to be seen by
the block layer. This will break functions such as blkdev_nr_zones() but
this patch is not changing this functions, and other using bit shift
calculations.

>  
>  	blk_queue_set_zoned(ns->disk, BLK_ZONED_HM);
>  	blk_queue_flag_set(QUEUE_FLAG_ZONE_RESETALL, q);
> @@ -129,7 +122,7 @@ static void *nvme_zns_alloc_report_buffer(struct nvme_ns *ns,
>  				   sizeof(struct nvme_zone_descriptor);
>  
>  	nr_zones = min_t(unsigned int, nr_zones,
> -			 get_capacity(ns->disk) >> ilog2(ns->zsze));
> +			 get_capacity(ns->disk) / ns->zsze);
>  
>  	bufsize = sizeof(struct nvme_zone_report) +
>  		nr_zones * sizeof(struct nvme_zone_descriptor);


-- 
Damien Le Moal
Western Digital Research