[PATCHv4 2/5] null_blk: introduce zone capacity for zoned device

[Himanshu Madhani]

> On Jun 29, 2020, at 2:06 PM, Keith Busch <kbusch at kernel.org> wrote:
> 
> From: Aravind Ramesh <aravind.ramesh at wdc.com>
> 
> Allow emulation of a zoned device with a per zone capacity smaller than
> the zone size as as defined in the Zoned Namespace (ZNS) Command Set
> specification. The zone capacity defaults to the zone size if not
> specified and must be smaller than the zone size otherwise.
> 
> Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni at wdc.com>
> Reviewed-by: Matias Bjørling <matias.bjorling at wdc.com>
> Reviewed-by: Daniel Wagner <dwagner at suse.de>
> Reviewed-by: Martin K. Petersen <martin.petersen at oracle.com>
> Reviewed-by: Johannes Thumshirn <johannes.thumshirn at wdc.com>
> Reviewed-by: Hannes Reinecke <hare at suse.de>
> Signed-off-by: Aravind Ramesh <aravind.ramesh at wdc.com>
> ---
> drivers/block/null_blk.h       |  1 +
> drivers/block/null_blk_main.c  | 10 +++++++++-
> drivers/block/null_blk_zoned.c | 16 ++++++++++++++--
> 3 files changed, 24 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/block/null_blk.h b/drivers/block/null_blk.h
> index 81b311c9d781..daed4a9c3436 100644
> --- a/drivers/block/null_blk.h
> +++ b/drivers/block/null_blk.h
> @@ -49,6 +49,7 @@ struct nullb_device {
> 	unsigned long completion_nsec; /* time in ns to complete a request */
> 	unsigned long cache_size; /* disk cache size in MB */
> 	unsigned long zone_size; /* zone size in MB if device is zoned */
> +	unsigned long zone_capacity; /* zone capacity in MB if device is zoned */
> 	unsigned int zone_nr_conv; /* number of conventional zones */
> 	unsigned int submit_queues; /* number of submission queues */
> 	unsigned int home_node; /* home node for the device */
> diff --git a/drivers/block/null_blk_main.c b/drivers/block/null_blk_main.c
> index 82259242b9b5..96d1adf6b818 100644
> --- a/drivers/block/null_blk_main.c
> +++ b/drivers/block/null_blk_main.c
> @@ -200,6 +200,10 @@ static unsigned long g_zone_size = 256;
> module_param_named(zone_size, g_zone_size, ulong, S_IRUGO);
> MODULE_PARM_DESC(zone_size, "Zone size in MB when block device is zoned. Must be power-of-two: Default: 256");
> 
> +static unsigned long g_zone_capacity;
> +module_param_named(zone_capacity, g_zone_capacity, ulong, 0444);
> +MODULE_PARM_DESC(zone_capacity, "Zone capacity in MB when block device is zoned. Can be less than or equal to zone size. Default: Zone size");
> +
> static unsigned int g_zone_nr_conv;
> module_param_named(zone_nr_conv, g_zone_nr_conv, uint, 0444);
> MODULE_PARM_DESC(zone_nr_conv, "Number of conventional zones when block device is zoned. Default: 0");
> @@ -341,6 +345,7 @@ NULLB_DEVICE_ATTR(mbps, uint, NULL);
> NULLB_DEVICE_ATTR(cache_size, ulong, NULL);
> NULLB_DEVICE_ATTR(zoned, bool, NULL);
> NULLB_DEVICE_ATTR(zone_size, ulong, NULL);
> +NULLB_DEVICE_ATTR(zone_capacity, ulong, NULL);
> NULLB_DEVICE_ATTR(zone_nr_conv, uint, NULL);
> 
> static ssize_t nullb_device_power_show(struct config_item *item, char *page)
> @@ -457,6 +462,7 @@ static struct configfs_attribute *nullb_device_attrs[] = {
> 	&nullb_device_attr_badblocks,
> 	&nullb_device_attr_zoned,
> 	&nullb_device_attr_zone_size,
> +	&nullb_device_attr_zone_capacity,
> 	&nullb_device_attr_zone_nr_conv,
> 	NULL,
> };
> @@ -510,7 +516,8 @@ nullb_group_drop_item(struct config_group *group, struct config_item *item)
> 
> static ssize_t memb_group_features_show(struct config_item *item, char *page)
> {
> -	return snprintf(page, PAGE_SIZE, "memory_backed,discard,bandwidth,cache,badblocks,zoned,zone_size,zone_nr_conv\n");
> +	return snprintf(page, PAGE_SIZE,
> +			"memory_backed,discard,bandwidth,cache,badblocks,zoned,zone_size,zone_capacity,zone_nr_conv\n");
> }
> 
> CONFIGFS_ATTR_RO(memb_group_, features);
> @@ -571,6 +578,7 @@ static struct nullb_device *null_alloc_dev(void)
> 	dev->use_per_node_hctx = g_use_per_node_hctx;
> 	dev->zoned = g_zoned;
> 	dev->zone_size = g_zone_size;
> +	dev->zone_capacity = g_zone_capacity;
> 	dev->zone_nr_conv = g_zone_nr_conv;
> 	return dev;
> }
> diff --git a/drivers/block/null_blk_zoned.c b/drivers/block/null_blk_zoned.c
> index 624aac09b005..3d25c9ad2383 100644
> --- a/drivers/block/null_blk_zoned.c
> +++ b/drivers/block/null_blk_zoned.c
> @@ -28,6 +28,15 @@ int null_init_zoned_dev(struct nullb_device *dev, struct request_queue *q)
> 		return -EINVAL;
> 	}
> 
> +	if (!dev->zone_capacity)
> +		dev->zone_capacity = dev->zone_size;
> +
> +	if (dev->zone_capacity > dev->zone_size) {
> +		pr_err("null_blk: zone capacity (%lu MB) larger than zone size (%lu MB)\n",
> +					dev->zone_capacity, dev->zone_size);
> +		return -EINVAL;
> +	}
> +
> 	dev->zone_size_sects = dev->zone_size << ZONE_SIZE_SHIFT;
> 	dev->nr_zones = dev_size >>
> 				(SECTOR_SHIFT + ilog2(dev->zone_size_sects));
> @@ -60,7 +69,7 @@ int null_init_zoned_dev(struct nullb_device *dev, struct request_queue *q)
> 
> 		zone->start = zone->wp = sector;
> 		zone->len = dev->zone_size_sects;
> -		zone->capacity = zone->len;
> +		zone->capacity = dev->zone_capacity << ZONE_SIZE_SHIFT;
> 		zone->type = BLK_ZONE_TYPE_SEQWRITE_REQ;
> 		zone->cond = BLK_ZONE_COND_EMPTY;
> 
> @@ -187,6 +196,9 @@ static blk_status_t null_zone_write(struct nullb_cmd *cmd, sector_t sector,
> 			return BLK_STS_IOERR;
> 		}
> 
> +		if (zone->wp + nr_sectors > zone->start + zone->capacity)
> +			return BLK_STS_IOERR;
> +
> 		if (zone->cond != BLK_ZONE_COND_EXP_OPEN)
> 			zone->cond = BLK_ZONE_COND_IMP_OPEN;
> 
> @@ -195,7 +207,7 @@ static blk_status_t null_zone_write(struct nullb_cmd *cmd, sector_t sector,
> 			return ret;
> 
> 		zone->wp += nr_sectors;
> -		if (zone->wp == zone->start + zone->len)
> +		if (zone->wp == zone->start + zone->capacity)
> 			zone->cond = BLK_ZONE_COND_FULL;
> 		return BLK_STS_OK;
> 	default:
> —
> 2.24.1
> 

Reviewed-by: Himanshu Madhani <himanshu.madhani at oracle.com>

--
Himanshu Madhani	Oracle Linux Engineering