Re: [PATCH v6 0/6] block/md/dm: set chunk_sectors from stacked dev stripe size

[Hannes Reinecke <hare@suse.de>]

On 7/14/25 08:13, Christoph Hellwig wrote:
> On Mon, Jul 14, 2025 at 03:00:57PM +0900, Damien Le Moal wrote:
>> Agreed, it would be nice to clean that up. BUT, the chunk_sectors sysfs
>> attribute file is reporting the zone size today. Changing that may break
>> applications. So I am not sure if we can actually do that, unless the sysfs
>> interface is considered as "unstable" ?
> 
> Good point.  I don't think it is considered unstable.
>
Hmm. It does, but really the meaning of 'chunk_sectors' (ie a boundary 
which I/O requests may not cross) hasn't changed. And that's also
the original use-case for the mapping of zone size to chunk_sectors,
namely to ensure that the block layer generates valid I/O.
So from that standpoint I guess we can change it; in the end, there may
(and will) be setups where 'chunk_sectors' is smaller than the zone
size.
We would need to have another attribute for the zone size, though :-)
But arguably we should have that even if we don't follow the above
reasoning.

Cheers,

Hannes
-- 
Dr. Hannes Reinecke                  Kernel Storage Architect
hare@suse.de                                +49 911 74053 688
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