Re: [PATCH v1 1/3] ublk: reject non-power-of-2 zone sizes in SET_PARAMS

On Thu, Aug 13, 2026 at 9:33 PM Yao Sang <[email protected]> wrote:
>
> UBLK_F_ZONED uses params.basic.chunk_sectors as zone size. ublk uses
> ilog2(chunk_sectors) to get number of zones, so the value must be power
> of 2.
>
> If chunk_sectors is 96 and dev_sectors is 96 * 16, userspace asks for
> 16 zones. But the shift calculation gets 24 zones.
>
> Block layer rejects such zone size when the disk is started. But
> SET_PARAMS has already returned success, which is confusing for
> userspace. Reject it in SET_PARAMS with other zoned parameter checks.
>
> Fixes: 29802d7ca33b ("ublk: enable zoned storage support")
> Signed-off-by: Yao Sang <[email protected]>
> ---
>  drivers/block/ublk_drv.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c
> index 853cd40a3403..193f6ebc3b37 100644
> --- a/drivers/block/ublk_drv.c
> +++ b/drivers/block/ublk_drv.c
> @@ -980,7 +980,7 @@ static int ublk_validate_params(const struct ublk_device *ub)
>                 if (p->max_sectors < PAGE_SECTORS)
>                         return -EINVAL;
>
> -               if (ublk_dev_is_zoned(ub) && !p->chunk_sectors)
> +               if (ublk_dev_is_zoned(ub) && !is_power_of_2(p->chunk_sectors))

Looks fine,  and is_power_of_2() returns false for 0.

Thanks,
Ming Lei