linux-kernel - Re: [PATCH v6 0/6] block/md/dm: set chunk

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <0a33bc37-bb9e-4e70-afd8-59366d46b250@suse.de>
Date: Tue, 15 Jul 2025 17:45:28 +0200
From: Hannes Reinecke <hare@...e.de>
To: Christoph Hellwig <hch@....de>, Damien Le Moal <dlemoal@...nel.org>
Cc: John Garry <john.g.garry@...cle.com>, agk@...hat.com, snitzer@...nel.org,
 mpatocka@...hat.com, song@...nel.org, yukuai3@...wei.com,
 nilay@...ux.ibm.com, axboe@...nel.dk, cem@...nel.org,
 dm-devel@...ts.linux.dev, linux-kernel@...r.kernel.org,
 linux-raid@...r.kernel.org, linux-block@...r.kernel.org,
 ojaswin@...ux.ibm.com, martin.petersen@...cle.com,
 akpm@...ux-foundation.org, linux-xfs@...r.kernel.org, djwong@...nel.org
Subject: Re: [PATCH v6 0/6] block/md/dm: set chunk_sectors from stacked dev
 stripe size

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@...e.de                                +49 911 74053 688
SUSE Software Solutions GmbH, Frankenstr. 146, 90461 Nürnberg
HRB 36809 (AG Nürnberg), GF: I. Totev, A. McDonald, W. Knoblich