Re: [PATCH 2/2] block: fix the length of a smaller last zone in blkdev_get_zone_info()

[shashank Jain]

On Mon, Oct 12, 2026, Christoph Hellwig wrote:
> Can you add this to blktests as a reproducer?

Will do. I'll send a blktests test under tests/zbd/ that sets up a zoned
null_blk device with a smaller last zone and checks that BLKREPORTZONEV2
without BLK_ZONE_REP_CACHED matches BLKREPORTZONE, and that the cached
report's last-zone length does not extend past the device. I'll post it
to the blktests project separately and reference this series.

Thanks,
Shashank

On Mon, Oct 12, 2026 at 5:51 PM Christoph Hellwig <hch@xxxxxx> wrote:
>
> On Sun, Oct 11, 2026 at 10:49:06AM +0530, Shashank Mohan Jain wrote:
> > blkdev_get_zone_info() sets the length of every zone to the zone size
> > of the device. The last zone of a zoned block device may be smaller
> > than the others: blk_revalidate_zone_cb() accepts that and remembers
> > the capacity of that zone in disk->last_zone_capacity. For such a zone
> > the length reported from the cached information is too large, and
> > start + len is beyond the end of the device. A conventional last zone
> > is also given the capacity of a full zone.
> >
> > Example with a zoned null_blk device of 10 MiB (20480 sectors) with
> > 4 MiB zones, last zone:
> >
> >   BLKREPORTZONE:       start 16384 len 4096 capacity 4096
> >   BLKREPORTZONEV2 with
> >   BLK_ZONE_REP_CACHED: start 16384 len 8192 capacity 4096
>
> Can you add this to blktests as a reproducer?
>
> The patch looks good:
>
>
> Reviewed-by: Christoph Hellwig <hch@xxxxxx>