From: Qu Wenruo <quwenruo.btrfs@gmx•com>
To: Christoph Hellwig <hch@lst•de>, "H. Peter Anvin" <hpa@zytor•com>
Cc: kreijack@inwind•it, David Sterba <dsterba@suse•cz>,
Andrew Morton <akpm@linux-foundation•org>,
Catalin Marinas <catalin.marinas@arm•com>,
Will Deacon <will@kernel•org>, Ard Biesheuvel <ardb@kernel•org>,
Huacai Chen <chenhuacai@kernel•org>,
WANG Xuerui <kernel@xen0n•name>,
Madhavan Srinivasan <maddy@linux•ibm.com>,
Michael Ellerman <mpe@ellerman•id.au>,
Nicholas Piggin <npiggin@gmail•com>,
"Christophe Leroy (CS GROUP)" <chleroy@kernel•org>,
Paul Walmsley <pjw@kernel•org>,
Palmer Dabbelt <palmer@dabbelt•com>,
Albert Ou <aou@eecs•berkeley.edu>,
Alexandre Ghiti <alex@ghiti•fr>,
Heiko Carstens <hca@linux•ibm.com>,
Vasily Gorbik <gor@linux•ibm.com>,
Alexander Gordeev <agordeev@linux•ibm.com>,
Christian Borntraeger <borntraeger@linux•ibm.com>,
Sven Schnelle <svens@linux•ibm.com>,
Thomas Gleixner <tglx@kernel•org>, Ingo Molnar <mingo@redhat•com>,
Borislav Petkov <bp@alien8•de>,
Dave Hansen <dave.hansen@linux•intel.com>,
x86@kernel•org, Herbert Xu <herbert@gondor•apana.org.au>,
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David Sterba <dsterba@suse•com>, Arnd Bergmann <arnd@arndb•de>,
Song Liu <song@kernel•org>,
Yu Kuai
<yukuai@alb-78bjiv52429oh8qptp•cn-shenzhen.alb.aliyuncs.com>,
Li Nan <linan122@huawei•com>,
linux-kernel@vger•kernel.org,
linux-arm-kernel@lists•infradead.org, loongarch@lists•linux.dev,
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linux-s390@vger•kernel.org, linux-crypto@vger•kernel.org,
linux-btrfs@vger•kernel.org, linux-arch@vger•kernel.org,
linux-raid@vger•kernel.org
Subject: Re: [PATCH 01/19] btrfs: require at least 4 devices for RAID 6
Date: Wed, 20 May 2026 18:11:09 +0930 [thread overview]
Message-ID: <f46636c8-80ba-4802-a6a0-74cbc35e7bee@gmx.com> (raw)
In-Reply-To: <20260518051207.GB9374@lst.de>
在 2026/5/18 14:42, Christoph Hellwig 写道:
> On Fri, May 15, 2026 at 12:59:34PM -0700, H. Peter Anvin wrote:
>> I don't think this is a good idea. Error out; it is the btrfs maintainers' job to ensure user data isn't lost.
>>
>> The RAID-6 code has *never* supported only 3 units, and if it ever worked for *any* of the implementations it was purely by accident. Speaking as the original author I should know; this was deliberate as in some cases the degenerate case (3) would have required extra trays in the code to no user benefit.
>>
>> I would not be surprised if the kernel crashed or corrupted the page cache in that case.
>
> It does, that's why I wanted to exclude it. Anyway, for the about to be
> resent version I'll drop this btrfs patch over the stated objection and
> will otherwise not change anything. This means the (IMHO hypothetical)
> users of this configuration will get a WARN_ON_ONCE triggered, but
> otherwise keep working (or rather not working) as before.
>
For the btrfs part, I believe I can get the current 2-disk-raid5 and
3-disk-raid6 to fallback to raid1 inside btrfs.
I hope the btrfs part can be finished and reach the next merge window,
but I'm not 100% sure.
What is the planned cycle to merge this raid5/6 cleanup?
Thanks,
Qu
next prev parent reply other threads:[~2026-05-20 8:43 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-05-12 5:20 cleanup the RAID6 P/Q library v2 Christoph Hellwig
2026-05-12 5:20 ` [PATCH 01/19] btrfs: require at least 4 devices for RAID 6 Christoph Hellwig
2026-05-12 11:42 ` David Sterba
2026-05-13 5:47 ` Christoph Hellwig
2026-05-13 20:19 ` David Sterba
2026-05-14 19:51 ` Goffredo Baroncelli
2026-05-14 19:57 ` H. Peter Anvin
2026-05-15 4:37 ` Christoph Hellwig
2026-05-15 14:51 ` David Sterba
2026-05-15 4:37 ` Christoph Hellwig
2026-05-15 16:50 ` Goffredo Baroncelli
2026-05-15 19:59 ` H. Peter Anvin
2026-05-18 5:12 ` Christoph Hellwig
2026-05-20 8:41 ` Qu Wenruo [this message]
2026-05-22 0:17 ` Andrew Morton
2026-05-22 0:27 ` Qu Wenruo
2026-05-13 16:14 ` H. Peter Anvin
2026-05-12 5:20 ` [PATCH 02/19] raid6: turn the userspace test harness into a kunit test Christoph Hellwig
2026-05-12 5:20 ` [PATCH 03/19] raid6: remove __KERNEL__ ifdefs Christoph Hellwig
2026-05-12 5:20 ` [PATCH 04/19] raid6: move to lib/raid/ Christoph Hellwig
2026-05-12 5:20 ` [PATCH 05/19] raid6: remove unused defines in pq.h Christoph Hellwig
2026-05-12 5:20 ` [PATCH 06/19] raid6: remove raid6_get_zero_page Christoph Hellwig
2026-05-12 5:20 ` [PATCH 07/19] raid6: use named initializers for struct raid6_calls Christoph Hellwig
2026-05-12 5:20 ` [PATCH 08/19] raid6: improve the public interface Christoph Hellwig
2026-05-12 5:20 ` [PATCH 09/19] raid6: hide internals Christoph Hellwig
2026-05-12 5:20 ` [PATCH 10/19] raid6: rework the init helpers Christoph Hellwig
2026-05-12 5:20 ` [PATCH 11/19] raid6: use static_call for gen_syndrom and xor_syndrom Christoph Hellwig
2026-05-12 5:20 ` [PATCH 12/19] raid6: use static_call for raid6_recov_2data and raid6_recov_datap Christoph Hellwig
2026-05-12 5:20 ` [PATCH 13/19] raid6: update top of file comments Christoph Hellwig
2026-05-12 5:20 ` [PATCH 14/19] raid6_kunit: use KUNIT_CASE_PARAM Christoph Hellwig
2026-05-12 5:20 ` [PATCH 15/19] raid6_kunit: dynamically allocate data buffers using vmalloc Christoph Hellwig
2026-05-12 5:20 ` [PATCH 16/19] raid6_kunit: cleanup dataptr handling Christoph Hellwig
2026-05-12 5:20 ` [PATCH 17/19] raid6_kunit: randomize parameters and increase limits Christoph Hellwig
2026-05-12 5:20 ` [PATCH 18/19] " Christoph Hellwig
2026-05-12 5:20 ` [PATCH 19/19] raid6_kunit: randomize buffer alignment Christoph Hellwig
2026-05-12 9:50 ` cleanup the RAID6 P/Q library v2 Ard Biesheuvel
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