linux-ext4 - Re: Bug#389772: e2fsprogs: e2fsck produces broken htree on ppc

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Message-ID: <20060930235717.GA3403@alea.gnuu.de>
Date:	Sun, 1 Oct 2006 01:57:17 +0200
From:	Jörg Sommer <joerg@...a.gnuu.de>
To:	Theodore Tso <tytso@....edu>
Cc:	Andreas Dilger <adilger@...sterfs.com>, 389772@...s.debian.org,
	paulus@...ibm.com, linux-ext4@...r.kernel.org
Subject: Re: Bug#389772: e2fsprogs: e2fsck produces broken htree on ppc

Hello Theodore,

Theodore Tso schrieb am Fri 29. Sep, 17:15 (-0400):
> If the filesystem is empty (or at least no no hashtree directories),
> then when the kernel creates new directories and expands to the point
> where they become indexed, they will be indexed with the PPC variant
> of the hash algorithm.  This will be self consistent, and everything
> will work fine --- until the filesystem gets corrupted to the point
> where e2fsprogs needs to rebuild one or more hashed directories.  At
> that point the directories will be rebuilt using the same conventions
> used by all other conventions, but the directories will no longer be
> useful on the PPC kernel.
> 
> Joerg, can you confirm this?

Yes.

> On a PPC machine, can you create a smallish ext3 filesystem (say, 4-8
> megabytes), create a directory with enough files in it that it becomes
> indexed (verify using lsattr), and show that it works just fine on a
> PPC.  Now take that image, and transfer it to an x86 machine;

I don't have a x86 machine.

> you should find that the kernel can't look up any of the directories on
> the x86 machine.  If you then run e2fsck -fD on that filesystem
> (running the e2fsck on either x86 or PPC; it shouldn't make a
> difference), then the resulting filesystem should work just fine on the
> x86, and fail on the PPC.

I put two files at http://www.minet.uni-jena.de/~joergs/ img-broken and
img-working. In the last image, img-working, I can access all files,
especially "test/broken fürß". The first image, img-broken, is the
image after running e2fsck -Df on img-working. So you can test if one
of these images work on x86, especially if the file "test/broken fürß"
is accessable.

Bye, Jörg.
-- 
Wer A sagt, muß nicht B sagen. Er kann auch erkennen, daß A falsch war.
      	    	      	       	       	    	(Erich Kästner)

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