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From: David Sterba <dsterba@suse.cz>
To: Qu Wenruo <wqu@suse.com>
Cc: linux-btrfs@vger.kernel.org
Subject: Re: [PATCH 0/2] btrfs-progs: check: avoid false alerts for --check-data-csum on RAID56
Date: Tue, 29 Mar 2022 23:02:37 +0200	[thread overview]
Message-ID: <20220329210237.GC2237@twin.jikos.cz> (raw)
In-Reply-To: <cover.1648546873.git.wqu@suse.com>

On Tue, Mar 29, 2022 at 05:44:24PM +0800, Qu Wenruo wrote:
> There is a long existing bug that btrfs-progs doesn't really support
> rebuilding its data using RAID56 P/Q.
> 
> This means any read with mirror_num > 1 for RAID56 won't work, and will
> just return the P/Q raw data directly.
> 
> The RAID56 ability in btrfs-progs is only for data write.
> 
> This will cause tons of false alerts for "btrfs check
> --check-data-csum", making it useless as an offline to verify RAID56
> data.
> 
> The proper fix will need way more code modification (btrfs-fuse supports
> that, so I believe it's possible).
> 
> But for now, let's just disable mirror_num > 1 read repair for progs.
> 
> Qu Wenruo (2):
>   btrfs-progs: avoid checking wrong RAID5/6 P/Q data
>   btrfs-progs: tests/fsck: add test case for data csum check on raid5

Added to devel with some fixups, thanks.

      parent reply	other threads:[~2022-03-29 21:06 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-03-29  9:44 [PATCH 0/2] btrfs-progs: check: avoid false alerts for --check-data-csum on RAID56 Qu Wenruo
2022-03-29  9:44 ` [PATCH 1/2] btrfs-progs: avoid checking wrong RAID5/6 P/Q data Qu Wenruo
2022-03-29 21:00   ` David Sterba
2022-03-29  9:44 ` [PATCH 2/2] btrfs-progs: tests/fsck: add test case for data csum check on raid5 Qu Wenruo
2022-03-29 21:01   ` David Sterba
2022-03-29 21:02 ` David Sterba [this message]

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