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From:   Damien Le Moal <Damien.LeMoal@wdc.com>
To:     Niklas Cassel <Niklas.Cassel@wdc.com>,
        Jonathan Corbet <corbet@lwn.net>, Jens Axboe <axboe@kernel.dk>,
        Keith Busch <kbusch@kernel.org>,
        Christoph Hellwig <hch@lst.de>,
        Sagi Grimberg <sagi@grimberg.me>,
        "James E.J. Bottomley" <jejb@linux.ibm.com>,
        "Martin K. Petersen" <martin.petersen@oracle.com>
CC:     =?iso-8859-1?Q?Javier_Gonz=E1lez?= <javier@javigon.com>,
        "linux-doc@vger.kernel.org" <linux-doc@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>,
        "linux-scsi@vger.kernel.org" <linux-scsi@vger.kernel.org>
Subject: Re: [PATCH v2 2/2] block: add max_active_zones to blk-sysfs
Thread-Topic: [PATCH v2 2/2] block: add max_active_zones to blk-sysfs
Thread-Index: AQHWUJ1p06hnAS8BF0W4ErHH9Q9yUQ==
Date:   Fri, 3 Jul 2020 05:04:29 +0000
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References: <20200702181922.24190-1-niklas.cassel@wdc.com>
 <20200702181922.24190-3-niklas.cassel@wdc.com>
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On 2020/07/03 3:20, Niklas Cassel wrote:=0A=
> Add a new max_active zones definition in the sysfs documentation.=0A=
> This definition will be common for all devices utilizing the zoned block=
=0A=
> device support in the kernel.=0A=
> =0A=
> Export max_active_zones according to this new definition for NVMe Zoned=
=0A=
> Namespace devices, ZAC ATA devices (which are treated as SCSI devices by=
=0A=
> the kernel), and ZBC SCSI devices.=0A=
> =0A=
> Add the new max_active_zones member to struct request_queue, rather=0A=
> than as a queue limit, since this property cannot be split across stackin=
g=0A=
> drivers.=0A=
> =0A=
> For SCSI devices, even though max active zones is not part of the ZBC/ZAC=
=0A=
> spec, export max_active_zones as 0, signifying "no limit".=0A=
> =0A=
> Signed-off-by: Niklas Cassel <niklas.cassel@wdc.com>=0A=
> Reviewed-by: Javier Gonz=E1lez <javier@javigon.com>=0A=
> ---=0A=
>  Documentation/block/queue-sysfs.rst |  7 +++++++=0A=
>  block/blk-sysfs.c                   | 14 +++++++++++++-=0A=
>  drivers/nvme/host/zns.c             |  1 +=0A=
>  drivers/scsi/sd_zbc.c               |  1 +=0A=
>  include/linux/blkdev.h              | 16 ++++++++++++++++=0A=
>  5 files changed, 38 insertions(+), 1 deletion(-)=0A=
> =0A=
> diff --git a/Documentation/block/queue-sysfs.rst b/Documentation/block/qu=
eue-sysfs.rst=0A=
> index f01cf8530ae4..f261a5c84170 100644=0A=
> --- a/Documentation/block/queue-sysfs.rst=0A=
> +++ b/Documentation/block/queue-sysfs.rst=0A=
> @@ -117,6 +117,13 @@ Maximum number of elements in a DMA scatter/gather l=
ist with integrity=0A=
>  data that will be submitted by the block layer core to the associated=0A=
>  block driver.=0A=
>  =0A=
> +max_active_zones (RO)=0A=
> +---------------------=0A=
> +For zoned block devices (zoned attribute indicating "host-managed" or=0A=
> +"host-aware"), the sum of zones belonging to any of the zone states:=0A=
> +EXPLICIT OPEN, IMPLICIT OPEN or CLOSED, is limited by this value.=0A=
> +If this value is 0, there is no limit.=0A=
> +=0A=
>  max_open_zones (RO)=0A=
>  -------------------=0A=
>  For zoned block devices (zoned attribute indicating "host-managed" or=0A=
> diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c=0A=
> index fa42961e9678..624bb4d85fc7 100644=0A=
> --- a/block/blk-sysfs.c=0A=
> +++ b/block/blk-sysfs.c=0A=
> @@ -310,6 +310,11 @@ static ssize_t queue_max_open_zones_show(struct requ=
est_queue *q, char *page)=0A=
>  	return queue_var_show(queue_max_open_zones(q), page);=0A=
>  }=0A=
>  =0A=
> +static ssize_t queue_max_active_zones_show(struct request_queue *q, char=
 *page)=0A=
> +{=0A=
> +	return queue_var_show(queue_max_active_zones(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=
> @@ -677,6 +682,11 @@ static struct queue_sysfs_entry queue_max_open_zones=
_entry =3D {=0A=
>  	.show =3D queue_max_open_zones_show,=0A=
>  };=0A=
>  =0A=
> +static struct queue_sysfs_entry queue_max_active_zones_entry =3D {=0A=
> +	.attr =3D {.name =3D "max_active_zones", .mode =3D 0444 },=0A=
> +	.show =3D queue_max_active_zones_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=
> @@ -776,6 +786,7 @@ static struct attribute *queue_attrs[] =3D {=0A=
>  	&queue_zoned_entry.attr,=0A=
>  	&queue_nr_zones_entry.attr,=0A=
>  	&queue_max_open_zones_entry.attr,=0A=
> +	&queue_max_active_zones_entry.attr,=0A=
>  	&queue_nomerges_entry.attr,=0A=
>  	&queue_rq_affinity_entry.attr,=0A=
>  	&queue_iostats_entry.attr,=0A=
> @@ -803,7 +814,8 @@ static umode_t queue_attr_visible(struct kobject *kob=
j, struct attribute *attr,=0A=
>  		(!q->mq_ops || !q->mq_ops->timeout))=0A=
>  			return 0;=0A=
>  =0A=
> -	if (attr =3D=3D &queue_max_open_zones_entry.attr &&=0A=
> +	if ((attr =3D=3D &queue_max_open_zones_entry.attr ||=0A=
> +	     attr =3D=3D &queue_max_active_zones_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 3d80b9cf6bfc..57cfd78731fb 100644=0A=
> --- a/drivers/nvme/host/zns.c=0A=
> +++ b/drivers/nvme/host/zns.c=0A=
> @@ -97,6 +97,7 @@ int nvme_update_zone_info(struct gendisk *disk, struct =
nvme_ns *ns,=0A=
>  	q->limits.zoned =3D BLK_ZONED_HM;=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=
>  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 aa3564139b40..d8b2c49d645b 100644=0A=
> --- a/drivers/scsi/sd_zbc.c=0A=
> +++ b/drivers/scsi/sd_zbc.c=0A=
> @@ -721,6 +721,7 @@ int sd_zbc_read_zones(struct scsi_disk *sdkp, unsigne=
d char *buf)=0A=
>  		blk_queue_max_open_zones(q, 0);=0A=
>  	else=0A=
>  		blk_queue_max_open_zones(q, sdkp->zones_max_open);=0A=
> +	blk_queue_max_active_zones(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 fe168abcfdda..bb9e6eb6a7e6 100644=0A=
> --- a/include/linux/blkdev.h=0A=
> +++ b/include/linux/blkdev.h=0A=
> @@ -521,6 +521,7 @@ struct request_queue {=0A=
>  	unsigned long		*conv_zones_bitmap;=0A=
>  	unsigned long		*seq_zones_wlock;=0A=
>  	unsigned int		max_open_zones;=0A=
> +	unsigned int		max_active_zones;=0A=
>  #endif /* CONFIG_BLK_DEV_ZONED */=0A=
>  =0A=
>  	/*=0A=
> @@ -741,6 +742,17 @@ static inline unsigned int queue_max_open_zones(cons=
t struct request_queue *q)=0A=
>  {=0A=
>  	return q->max_open_zones;=0A=
>  }=0A=
> +=0A=
> +static inline void blk_queue_max_active_zones(struct request_queue *q,=
=0A=
> +		unsigned int max_active_zones)=0A=
> +{=0A=
> +	q->max_active_zones =3D max_active_zones;=0A=
> +}=0A=
> +=0A=
> +static inline unsigned int queue_max_active_zones(const struct request_q=
ueue *q)=0A=
> +{=0A=
> +	return q->max_active_zones;=0A=
> +}=0A=
>  #else /* CONFIG_BLK_DEV_ZONED */=0A=
>  static inline unsigned int blk_queue_nr_zones(struct request_queue *q)=
=0A=
>  {=0A=
> @@ -760,6 +772,10 @@ static inline unsigned int queue_max_open_zones(cons=
t struct request_queue *q)=0A=
>  {=0A=
>  	return 0;=0A=
>  }=0A=
> +static inline unsigned int queue_max_active_zones(const struct request_q=
ueue *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=
Looks good to me.=0A=
=0A=
Reviewed-by: Damien Le Moal <damien.lemoal@wdc.com>=0A=
=0A=
=0A=
-- =0A=
Damien Le Moal=0A=
Western Digital Research=0A=