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From:   Damien Le Moal <Damien.LeMoal@wdc.com>
To:     Matias Bjorling <Matias.Bjorling@wdc.com>,
        "axboe@kernel.dk" <axboe@kernel.dk>,
        "kbusch@kernel.org" <kbusch@kernel.org>, "hch@lst.de" <hch@lst.de>,
        "sagi@grimberg.me" <sagi@grimberg.me>,
        "martin.petersen@oracle.com" <martin.petersen@oracle.com>,
        Niklas Cassel <Niklas.Cassel@wdc.com>,
        Hans Holmberg <Hans.Holmberg@wdc.com>
CC:     "linux-scsi@vger.kernel.org" <linux-scsi@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "linux-block@vger.kernel.org" <linux-block@vger.kernel.org>,
        "linux-nvme@lists.infradead.org" <linux-nvme@lists.infradead.org>
Subject: Re: [PATCH 1/2] block: add zone_desc_ext_bytes to sysfs
Thread-Topic: [PATCH 1/2] block: add zone_desc_ext_bytes to sysfs
Thread-Index: AQHWTaAexT5EBQ0B+0awwAwr0pDYRw==
Date:   Mon, 29 Jun 2020 00:52:46 +0000
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References: <20200628230102.26990-1-matias.bjorling@wdc.com>
 <20200628230102.26990-2-matias.bjorling@wdc.com>
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On 2020/06/29 8:01, Matias Bjorling wrote:=0A=
> The NVMe Zoned Namespace Command Set adds support for associating=0A=
> data to a zone through the Zone Descriptor Extension feature.=0A=
> =0A=
> The Zone Descriptor Extension size is fixed to a multiple of 64=0A=
> bytes. A value of zero communicates the feature is not available.=0A=
> A value larger than zero communites the feature is available, and=0A=
> the specified Zone Descriptor Extension size in bytes.=0A=
> =0A=
> The Zone Descriptor Extension feature is only available in the=0A=
> NVMe Zoned Namespaces Command Set. Devices that supports ZAC/ZBC=0A=
> therefore reports this value as zero, where as the NVMe device=0A=
> driver reports the Zone Descriptor Extension size from the=0A=
> specific device.=0A=
> =0A=
> Signed-off-by: Matias Bj=F8rling <matias.bjorling@wdc.com>=0A=
> ---=0A=
>  Documentation/block/queue-sysfs.rst |  6 ++++++=0A=
>  block/blk-sysfs.c                   | 15 ++++++++++++++-=0A=
>  drivers/nvme/host/zns.c             |  1 +=0A=
>  drivers/scsi/sd_zbc.c               |  1 +=0A=
>  include/linux/blkdev.h              | 22 ++++++++++++++++++++++=0A=
>  5 files changed, 44 insertions(+), 1 deletion(-)=0A=
> =0A=
> diff --git a/Documentation/block/queue-sysfs.rst b/Documentation/block/qu=
eue-sysfs.rst=0A=
> index f261a5c84170..c4fa195c87b4 100644=0A=
> --- a/Documentation/block/queue-sysfs.rst=0A=
> +++ b/Documentation/block/queue-sysfs.rst=0A=
> @@ -265,4 +265,10 @@ devices are described in the ZBC (Zoned Block Comman=
ds) and ZAC=0A=
>  do not support zone commands, they will be treated as regular block devi=
ces=0A=
>  and zoned will report "none".=0A=
>  =0A=
> +zone_desc_ext_bytes (RO)=0A=
> +-------------------------=0A=
> +This indicates the zone description extension (ZDE) size, in bytes, of a=
 zoned=0A=
> +block device. A value of '0' means that zone description extension is no=
t=0A=
> +supported.=0A=
> +=0A=
>  Jens Axboe <jens.axboe@oracle.com>, February 2009=0A=
> diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c=0A=
> index 624bb4d85fc7..0c99454823b7 100644=0A=
> --- a/block/blk-sysfs.c=0A=
> +++ b/block/blk-sysfs.c=0A=
> @@ -315,6 +315,12 @@ static ssize_t queue_max_active_zones_show(struct re=
quest_queue *q, char *page)=0A=
>  	return queue_var_show(queue_max_active_zones(q), page);=0A=
>  }=0A=
>  =0A=
> +static ssize_t queue_zone_desc_ext_bytes_show(struct request_queue *q,=
=0A=
> +		char *page)=0A=
> +{=0A=
> +	return queue_var_show(queue_zone_desc_ext_bytes(q), page);=0A=
> +}=0A=
> +=0A=
>  static ssize_t queue_nomerges_show(struct request_queue *q, char *page)=
=0A=
>  {=0A=
>  	return queue_var_show((blk_queue_nomerges(q) << 1) |=0A=
> @@ -687,6 +693,11 @@ static struct queue_sysfs_entry queue_max_active_zon=
es_entry =3D {=0A=
>  	.show =3D queue_max_active_zones_show,=0A=
>  };=0A=
>  =0A=
> +static struct queue_sysfs_entry queue_zone_desc_ext_bytes_entry =3D {=0A=
> +	.attr =3D {.name =3D "zone_desc_ext_bytes", .mode =3D 0444 },=0A=
> +	.show =3D queue_zone_desc_ext_bytes_show,=0A=
> +};=0A=
> +=0A=
>  static struct queue_sysfs_entry queue_nomerges_entry =3D {=0A=
>  	.attr =3D {.name =3D "nomerges", .mode =3D 0644 },=0A=
>  	.show =3D queue_nomerges_show,=0A=
> @@ -787,6 +798,7 @@ static struct attribute *queue_attrs[] =3D {=0A=
>  	&queue_nr_zones_entry.attr,=0A=
>  	&queue_max_open_zones_entry.attr,=0A=
>  	&queue_max_active_zones_entry.attr,=0A=
=0A=
Which tree is this patch based on ? Not I have seen any patch introducing m=
ax=0A=
active zones.=0A=
=0A=
> +	&queue_zone_desc_ext_bytes_entry.attr,=0A=
>  	&queue_nomerges_entry.attr,=0A=
>  	&queue_rq_affinity_entry.attr,=0A=
>  	&queue_iostats_entry.attr,=0A=
> @@ -815,7 +827,8 @@ static umode_t queue_attr_visible(struct kobject *kob=
j, struct attribute *attr,=0A=
>  			return 0;=0A=
>  =0A=
>  	if ((attr =3D=3D &queue_max_open_zones_entry.attr ||=0A=
> -	     attr =3D=3D &queue_max_active_zones_entry.attr) &&=0A=
> +	     attr =3D=3D &queue_max_active_zones_entry.attr ||=0A=
> +	     attr =3D=3D &queue_zone_desc_ext_bytes_entry.attr) &&=0A=
>  	    !blk_queue_is_zoned(q))=0A=
>  		return 0;=0A=
>  =0A=
> diff --git a/drivers/nvme/host/zns.c b/drivers/nvme/host/zns.c=0A=
> index 502070763266..5792d953a8f3 100644=0A=
> --- a/drivers/nvme/host/zns.c=0A=
> +++ b/drivers/nvme/host/zns.c=0A=
> @@ -84,6 +84,7 @@ int nvme_update_zone_info(struct gendisk *disk, struct =
nvme_ns *ns,=0A=
>  	blk_queue_flag_set(QUEUE_FLAG_ZONE_RESETALL, q);=0A=
>  	blk_queue_max_open_zones(q, le32_to_cpu(id->mor) + 1);=0A=
>  	blk_queue_max_active_zones(q, le32_to_cpu(id->mar) + 1);=0A=
> +	blk_queue_zone_desc_ext_bytes(q, id->lbafe[lbaf].zdes << 6);=0A=
>  free_data:=0A=
>  	kfree(id);=0A=
>  	return status;=0A=
> diff --git a/drivers/scsi/sd_zbc.c b/drivers/scsi/sd_zbc.c=0A=
> index d8b2c49d645b..a4b6d6cf5457 100644=0A=
> --- a/drivers/scsi/sd_zbc.c=0A=
> +++ b/drivers/scsi/sd_zbc.c=0A=
> @@ -722,6 +722,7 @@ int sd_zbc_read_zones(struct scsi_disk *sdkp, unsigne=
d char *buf)=0A=
>  	else=0A=
>  		blk_queue_max_open_zones(q, sdkp->zones_max_open);=0A=
>  	blk_queue_max_active_zones(q, 0);=0A=
> +	blk_queue_zone_desc_ext_bytes(q, 0);=0A=
>  	nr_zones =3D round_up(sdkp->capacity, zone_blocks) >> ilog2(zone_blocks=
);=0A=
>  =0A=
>  	/* READ16/WRITE16 is mandatory for ZBC disks */=0A=
> diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h=0A=
> index 3776140f8f20..2ed55055f68d 100644=0A=
> --- a/include/linux/blkdev.h=0A=
> +++ b/include/linux/blkdev.h=0A=
> @@ -522,6 +522,7 @@ struct request_queue {=0A=
>  	unsigned long		*seq_zones_wlock;=0A=
>  	unsigned int		max_open_zones;=0A=
>  	unsigned int		max_active_zones;=0A=
> +	unsigned int		zone_desc_ext_bytes;=0A=
=0A=
Why is this not a queue limit ? This may need to be to be gracefully handle=
d by=0A=
device mapper for a target device using multiple zoned drives.=0A=
=0A=
>  #endif /* CONFIG_BLK_DEV_ZONED */=0A=
>  =0A=
>  	/*=0A=
> @@ -753,6 +754,18 @@ static inline unsigned int queue_max_active_zones(co=
nst struct request_queue *q)=0A=
>  {=0A=
>  	return q->max_active_zones;=0A=
>  }=0A=
> +=0A=
> +static inline void blk_queue_zone_desc_ext_bytes(struct request_queue *q=
,=0A=
> +		unsigned int zone_desc_ext_bytes)=0A=
> +{=0A=
> +	q->zone_desc_ext_bytes =3D zone_desc_ext_bytes;=0A=
> +}=0A=
> +=0A=
> +static inline unsigned int queue_zone_desc_ext_bytes(=0A=
> +		const struct request_queue *q)=0A=
> +{=0A=
> +	return q->zone_desc_ext_bytes;=0A=
> +}=0A=
>  #else /* CONFIG_BLK_DEV_ZONED */=0A=
>  static inline unsigned int blk_queue_nr_zones(struct request_queue *q)=
=0A=
>  {=0A=
> @@ -784,6 +797,15 @@ static inline unsigned int queue_max_active_zones(co=
nst struct request_queue *q)=0A=
>  {=0A=
>  	return 0;=0A=
>  }=0A=
> +static inline void blk_queue_zone_desc_ext_bytes(struct request_queue *q=
,=0A=
> +		unsigned int zone_desc_ext_bytes)=0A=
> +{=0A=
> +}=0A=
> +static inline unsigned int queue_zone_desc_ext_bytes(=0A=
> +		const struct request_queue *q)=0A=
> +{=0A=
> +	return 0;=0A=
> +}=0A=
>  #endif /* CONFIG_BLK_DEV_ZONED */=0A=
>  =0A=
>  static inline bool rq_is_sync(struct request *rq)=0A=
> =0A=
=0A=
=0A=
-- =0A=
Damien Le Moal=0A=
Western Digital Research=0A=