Re: [PATCH 00/16] support non power of 2 zoned devices

[Pankaj Raghav]

On 2022-05-04 23:14, David Sterba wrote:
>> This commit: `btrfs: zoned: relax the alignment constraint for zoned
>> devices` makes sure the zone size is BTRFS_STRIPE_LEN aligned (64K). So
>> even the npo2 zoned device should be aligned to `fs_info->sectorsize`,
>> which is typically 4k.
>>
>> This was one of the comment that came from David Sterba:
>> https://lore.kernel.org/all/20220315142740.GU12643@xxxxxxxxxxxxx/
>> where he suggested to have some sane alignment for the zone sizes.
> 
> My idea of 'sane' value would be 1M, that we have 4K for sectors is
> because of the 1:1 mapping to pages, but RAM sizes are on a different
> scale than storage devices. The 4K is absolute minimum but if the page
> size is taken as a basic constraint, ARM has 64K and there are some 256K
> arches.

That is a good point. I think it is safe to have 1MB as the minimum
alignment so that it covers all architecture's page sizes. Thanks. I
will queue this up.