[PATCH v2 06/28] block: Remember zone capacity when revalidating zones

[Damien Le Moal <dlemoal@kernel.org>]

In preparation for adding zone write plugging, modify
blk_revalidate_disk_zones() to get the capacity of zones of a zoned
block device. This capacity value as a number of 512B sectors is stored
in the gendisk zone_capacity field.

Given that host-managed SMR disks (including zoned UFS drives) and all
known NVMe ZNS devices have the same zone capacity for all zones
blk_revalidate_disk_zones() returns an error if different capacities are
detected for different zones.

Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
---
 block/blk-zoned.c      | 15 +++++++++++++++
 include/linux/blkdev.h |  1 +
 2 files changed, 16 insertions(+)

diff --git a/block/blk-zoned.c b/block/blk-zoned.c
index da0f4b2a8fa0..88110a1329cd 100644
--- a/block/blk-zoned.c
+++ b/block/blk-zoned.c
@@ -438,6 +438,7 @@ struct blk_revalidate_zone_args {
 	unsigned long	*conv_zones_bitmap;
 	unsigned long	*seq_zones_wlock;
 	unsigned int	nr_zones;
+	unsigned int	zone_capacity;
 	sector_t	sector;
 };
 
@@ -500,6 +501,18 @@ static int blk_revalidate_zone_cb(struct blk_zone *zone, unsigned int idx,
 			if (!args->seq_zones_wlock)
 				return -ENOMEM;
 		}
+
+		/*
+		 * Remember the capacity of the first sequential zone and check
+		 * if it is constant for all zones.
+		 */
+		if (!args->zone_capacity)
+			args->zone_capacity = zone->capacity;
+		if (zone->capacity != args->zone_capacity) {
+			pr_warn("%s: Invalid variable zone capacity\n",
+				disk->disk_name);
+			return -ENODEV;
+		}
 		break;
 	case BLK_ZONE_TYPE_SEQWRITE_PREF:
 	default:
@@ -597,6 +610,7 @@ int blk_revalidate_disk_zones(struct gendisk *disk,
 		disk->nr_zones = args.nr_zones;
 		swap(disk->seq_zones_wlock, args.seq_zones_wlock);
 		swap(disk->conv_zones_bitmap, args.conv_zones_bitmap);
+		disk->zone_capacity = args.zone_capacity;
 		if (update_driver_data)
 			update_driver_data(disk);
 		ret = 0;
@@ -608,6 +622,7 @@ int blk_revalidate_disk_zones(struct gendisk *disk,
 
 	kfree(args.seq_zones_wlock);
 	kfree(args.conv_zones_bitmap);
+
 	return ret;
 }
 EXPORT_SYMBOL_GPL(blk_revalidate_disk_zones);
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 93f93f352b54..b57244ee74f0 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -191,6 +191,7 @@ struct gendisk {
 	 * blk_mq_unfreeze_queue().
 	 */
 	unsigned int		nr_zones;
+	unsigned int		zone_capacity;
 	unsigned long		*conv_zones_bitmap;
 	unsigned long		*seq_zones_wlock;
 #endif /* CONFIG_BLK_DEV_ZONED */
-- 
2.44.0