block: Remember zone capacity when revalidating zones

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.

This also adds check to verify that the values reported by the device
for zone capacities are correct, that is, that the zone capacity is
never 0, does not exceed the zone size and is equal to the zone size for
conventional zones.
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Tested-by: Hans Holmberg <hans.holmberg@wdc.com>
Tested-by: Dennis Maisenbacher <dennis.maisenbacher@wdc.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Link: https://lore.kernel.org/r/20240408014128.205141-7-dlemoal@kernel.orgSigned-off-by: Jens Axboe <axboe@kernel.dk>

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;
 };
 
@@ -482,9 +483,20 @@ static int blk_revalidate_zone_cb(struct blk_zone *zone, unsigned int idx,
 		return -ENODEV;
 	}
 
+	if (!zone->capacity || zone->capacity > zone->len) {
+		pr_warn("%s: Invalid zone capacity\n",
+			disk->disk_name);
+		return -ENODEV;
+	}
+
 	/* Check zone type */
 	switch (zone->type) {
 	case BLK_ZONE_TYPE_CONVENTIONAL:
+		if (zone->capacity != zone->len) {
+			pr_warn("%s: Invalid conventional zone capacity\n",
+				disk->disk_name);
+			return -ENODEV;
+		}
 		if (!args->conv_zones_bitmap) {
 			args->conv_zones_bitmap =
 				blk_alloc_zone_bitmap(q->node, args->nr_zones);
@@ -500,6 +512,18 @@ 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:
@@ -595,6 +619,7 @@ int blk_revalidate_disk_zones(struct gendisk *disk,
 	blk_mq_freeze_queue(q);
 	if (ret > 0) {
 		disk->nr_zones = args.nr_zones;
+		disk->zone_capacity = args.zone_capacity;
 		swap(disk->seq_zones_wlock, args.seq_zones_wlock);
 		swap(disk->conv_zones_bitmap, args.conv_zones_bitmap);
 		if (update_driver_data)
@@ -608,6 +633,7 @@ 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);

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 */