Re: [PATCH v2] Documentation: block: zloop: clarify capacity alignment

[Damien Le Moal]

On 8/4/26 12:41, raoxu wrote:
> From: Xu Rao <raoxu@xxxxxxxxxxxxx>
> 
> zloop divides the requested capacity by the zone size to determine the
> number of zones. Since it uses one zone size for all zones, a smaller last
> zone is not supported and an unaligned capacity is rounded down.
> 
> The capacity_mb description incorrectly states that the capacity is rounded
> up. Correct it to document the actual behavior.
> 
> Fixes: 9e4f11c1228c ("Documentation: Document the new zoned loop block device driver")
> Suggested-by: Damien Le Moal <dlemoal@xxxxxxxxxx>
> Signed-off-by: Xu Rao <raoxu@xxxxxxxxxxxxx>
> ---
> Changes in v2:
> - Replace the code change with a documentation correction.
> - State that a smaller last zone is unsupported and that an unaligned
>   capacity is rounded down.
> 
>  Documentation/admin-guide/blockdev/zoned_loop.rst | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/Documentation/admin-guide/blockdev/zoned_loop.rst b/Documentation/admin-guide/blockdev/zoned_loop.rst
> index f4f1f31..fd99e5c 100644
> --- a/Documentation/admin-guide/blockdev/zoned_loop.rst
> +++ b/Documentation/admin-guide/blockdev/zoned_loop.rst
> @@ -71,8 +71,9 @@ follows.
>  ===================   =========================================================
>  id                    Device number (the X in /dev/zloopX).
>                        Default: automatically assigned.
> -capacity_mb           Device total capacity in MiB. This is always rounded up
> -                      to the nearest higher multiple of the zone size.
> +capacity_mb           Device total capacity in MiB. A smaller last zone is not
> +                      supported, so an unaligned value is rounded down to a
> +                      zone-size multiple.

Let's make this a proper sentence:

capacity_mb		Device total capacity in MiB. A smaller last zone is not
			supported, so a capacity value that is not multiple of
			the zone size is rounded down to the closest multiple of
			the zone-size.

With that,

Reviewed-by: Damien Le Moal <dlemoal@xxxxxxxxxx>

>                        Default: 16384 MiB (16 GiB).
>  zone_size_mb          Device zone size in MiB. Default: 256 MiB.
>  zone_capacity_mb      Device zone capacity (must always be equal to or lower
> --
> 2.47.3
> 
> 


-- 
Damien Le Moal
Western Digital Research