Re: [PATCH 5/6] block: add zone attr. to zone mgmt IOCTL struct

["Matias Bjørling" <mb@lightnvm.io>]

On 25/06/2020 14.21, Javier González wrote:
> From: Javier González <javier.gonz@samsung.com>
>
> Add zone attributes field to the blk_zone structure. Use ZNS attributes
> as base for zoned block devices in general.
>
> Signed-off-by: Javier González <javier.gonz@samsung.com>
> Signed-off-by: SelvaKumar S <selvakuma.s1@samsung.com>
> Signed-off-by: Kanchan Joshi <joshi.k@samsung.com>
> Signed-off-by: Nitesh Shetty <nj.shetty@samsung.com>
> ---
>   drivers/nvme/host/zns.c       |  1 +
>   include/uapi/linux/blkzoned.h | 13 ++++++++++++-
>   2 files changed, 13 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/nvme/host/zns.c b/drivers/nvme/host/zns.c
> index 258d03610cc0..7d8381fe7665 100644
> --- a/drivers/nvme/host/zns.c
> +++ b/drivers/nvme/host/zns.c
> @@ -195,6 +195,7 @@ static int nvme_zone_parse_entry(struct nvme_ns *ns,
>   	zone.capacity = nvme_lba_to_sect(ns, le64_to_cpu(entry->zcap));
>   	zone.start = nvme_lba_to_sect(ns, le64_to_cpu(entry->zslba));
>   	zone.wp = nvme_lba_to_sect(ns, le64_to_cpu(entry->wp));
> +	zone.attr = entry->za;
>   
>   	return cb(&zone, idx, data);
>   }
> diff --git a/include/uapi/linux/blkzoned.h b/include/uapi/linux/blkzoned.h
> index 0c49a4b2ce5d..2e43a00e3425 100644
> --- a/include/uapi/linux/blkzoned.h
> +++ b/include/uapi/linux/blkzoned.h
> @@ -82,6 +82,16 @@ enum blk_zone_report_flags {
>   	BLK_ZONE_REP_CAPACITY	= (1 << 0),
>   };
>   
> +/**
> + * Zone Attributes
> + */
> +enum blk_zone_attr {
> +	BLK_ZONE_ATTR_ZFC	= 1 << 0,
> +	BLK_ZONE_ATTR_FZR	= 1 << 1,
> +	BLK_ZONE_ATTR_RZR	= 1 << 2,

The RZR bit is equivalent to the RESET bit accessible through the reset 
byte in struct blk_zone.

ZFC is tied to Zone Active Excursions, as there is no support in the 
kernel zone model for that. This should probably not be added until 
there is generic support.

Damien, could we overload the struct blk_zine reset variable for FZR? I 
don't believe we can due to backward compatibility. Is that your 
understanding as well?

> +	BLK_ZONE_ATTR_ZDEV	= 1 << 7,

There is not currently an equivalent for zone descriptor extensions in 
ZAC/ZBC. The addition of this field should probably be in a patch that 
adds generic support for zone descriptor extensions.

> +};
> +
>   /**
>    * struct blk_zone - Zone descriptor for BLKREPORTZONE ioctl.
>    *
> @@ -108,7 +118,8 @@ struct blk_zone {
>   	__u8	cond;		/* Zone condition */
>   	__u8	non_seq;	/* Non-sequential write resources active */
>   	__u8	reset;		/* Reset write pointer recommended */
> -	__u8	resv[4];
> +	__u8	attr;		/* Zone attributes */
> +	__u8	resv[3];
>   	__u64	capacity;	/* Zone capacity in number of sectors */
>   	__u8	reserved[24];
>   };