Re: [PATCH 3/4] block: Fix zone write plugging handling of devices with a runt zone

[Niklas Cassel <cassel@kernel.org>]

On Thu, May 30, 2024 at 02:40:34PM +0900, Damien Le Moal wrote:
> A zoned device may have a last sequential write required zone that is
> smaller than other zones. However, all tests to check if a zone write
> plug write offset exceeds the zone capacity use the same capacity
> value stored in the gendisk zone_capacity field. This is incorrect for a
> zoned device with a last runt (smaller) zone.
> 
> Add the new field last_zone_capacity to struct gendisk to store the
> capacity of the last zone of the device. blk_revalidate_seq_zone() and
> blk_revalidate_conv_zone() are both modified to get this value when
> disk_zone_is_last() returns true. Similarly to zone_capacity, the value
> is first stored using the last_zone_capacity field of struct
> blk_revalidate_zone_args. Once zone revalidation of all zones is done,
> this is used to set the gendisk last_zone_capacity field.
> 
> The checks to determine if a zone is full or if a sector offset in a
> zone exceeds the zone capacity in disk_should_remove_zone_wplug(),
> disk_zone_wplug_abort_unaligned(), blk_zone_write_plug_init_request(),
> and blk_zone_wplug_prepare_bio() are modified to use the new helper
> functions disk_zone_is_full() and disk_zone_wplug_is_full().
> disk_zone_is_full() uses the zone index to determine if the zone being
> tested is the last one of the disk and uses the either the disk
> zone_capacity or last_zone_capacity accordingly.
> 
> Fixes: dd291d77cc90 ("block: Introduce zone write plugging")
> Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
> ---

Reviewed-by: Niklas Cassel <cassel@kernel.org>