linux-ext4 - Re: xfstests failures w/ metadata

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Message-ID: <20141201220209.GS10043@birch.djwong.org>
Date:	Mon, 1 Dec 2014 14:02:09 -0800
From:	"Darrick J. Wong" <darrick.wong@...cle.com>
To:	"Theodore Ts'o" <tytso@....edu>
Cc:	linux-ext4@...r.kernel.org, Eric Whitney <enwlinux@...il.com>
Subject: Re: xfstests failures w/ metadata_csum

CRAP.

The real cause of the regression that Eric reported is: The first time we
enable journal_checksum on a journal, we fail to set the checksum seed because
the seed calculation is gated on jbd2_journal_has_csum_v2or3() ... before we
actually set the superblock feature fields!  Yikes!

The fix is to get rid of the braindead check and always calculate the seed.

I will have a regression fix for 3.18-rc7 out shortly.

(I'll also post a patch to complain loudly, but that isn't critical.)

--D

On Mon, Dec 01, 2014 at 12:20:45PM -0800, Darrick J. Wong wrote:
> Hi Eric,
> 
> Could you remind me which xfstests are failing in 3.18-rc3+ with metadata_csum
> enabled?  I think you said generic/034, generic/321, and generic/322, but were
> there more?
> 
> AFAICT the ext4 mount fails because it can't load the journal, and the journal
> can't replay because jbd2_descr_block_csum_verify() fails; the 034 test appears
> to drop all the writes related to the umount.  recovery.c doesn't say anything
> when the journal descriptor block fails csum verification, though it should.
> Not sure why we end up with corrupt-looking descriptor blocks.
> 
> The reason why this appears in -rc3 is because that's when we added the patch
> that forces journal_checksum on whenever metadata_csum is on, and I guess
> few people were testing journal_checksum with xfstests before that.
> 
> --D
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