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Re: xfsdump SGI_FS_BULKSTAT errno = 22, how could this IRIX bug get into

To: Dave Chinner <david@xxxxxxxxxxxxx>
Subject: Re: xfsdump SGI_FS_BULKSTAT errno = 22, how could this IRIX bug get into Ubuntu 10.04 Lucid between kernels 2.6.32-27 and 2.6.32-26?
From: Bill Kendall <wkendall@xxxxxxx>
Date: Tue, 08 Feb 2011 19:24:45 -0600
Cc: Michael Lueck <mlueck@xxxxxxxxxxxxxxxxxxxx>, linux-xfs@xxxxxxxxxxx, Dann Frazier <dannf@xxxxxxxxxx>
In-reply-to: <20110207220421.GD2559@dastard>
References: <iibmah$dlp$1@xxxxxxxxxxxxxxx> <4D49A35B.6030009@xxxxxxx> <20110203045836.GV11040@dastard> <4D4ABEF7.7000400@xxxxxxxxxxxxxxxxxxxx> <20110204000823.GW11040@dastard> <4D4C0965.9010905@xxxxxxxxxxxxxxxxxxxx> <20110204204927.GZ11040@dastard> <4D505C48.8050203@xxxxxxx> <20110207212320.GC2559@dastard> <4D506744.9010303@xxxxxxx> <20110207220421.GD2559@dastard>
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On 02/07/2011 04:04 PM, Dave Chinner wrote:
On Mon, Feb 07, 2011 at 03:42:28PM -0600, Bill Kendall wrote:
On 02/07/2011 03:23 PM, Dave Chinner wrote:
On Mon, Feb 07, 2011 at 02:55:36PM -0600, Bill Kendall wrote:
On 02/04/2011 02:49 PM, Dave Chinner wrote:
On Fri, Feb 04, 2011 at 09:12:53AM -0500, Michael Lueck wrote:
Dave Chinner wrote:
Ok, so xfsdump i seeing a short bulkstat, then an EINVAL returned
>from the next bulkstat. That's not a race condition, and makes me
think you have some kind of on-disk corruption.

Very odd that some kind of on-disk corruption is suddenly causing
xfsdump problems starting with Ubuntu 10.04 (Lucid) kernel
2.6.32-27 and persisting in 2.6.32-28.

Not really. The newer kernels have code in them that does more
validity checks than previous kernels, so older kernels would have
erroneously and silently returned unlinked files to xfsdump and have
them backed up. IOWs, you'd never notice such a corruption with
xfsdump. On the new kernel, xfsdump gets an EINVAL error to such
occurrences, which it should have in the first place.

And there is one other person who confirmed this xfsdump problem
running Lucid with kernel 2.6.32-28. They reported their "me too"
in the Ubuntu bug tracker.

Could it be that 2.6.32-26 and prior managed to write something to
disk corrupted, and the newer code is tripping on it?

That's what I'm trying to find out. Or it could be something as
simple as your disk has had an undetected bit error that has flipped
a bit in the inode allocation btree.

Hi Dave,

I am able to reproduce this on a system running Ubuntu 10.4
(2.6.32-28). I took a metadump of the filesystem and moved it to
a system running 10.10 (2.6.35-25), and was able to successfully
dump it there. Likewise it dumps fine on 2.6.38-rc1. So this
suggests an issue with the Ubuntu 10.4 kernel.

2.6.35 hasn't had the untrusted inode lookup patches back ported to
it, so it's no surprise that it isn't having problems - it's just
like the older 2.6.32 kernels.

I thought it landed in 2.6.35 and then a regression was fixed in
2.6.36. The untrusted inode lookup changes are referenced here:

My bad, I just checked the regression fix. I have no idea if it got
back ported to 2.6.35-stable or not - it probably didn't judging by
your results.....

Hmmm, can you find out if there is any specific pattern to the inode
numbers that are returning EINVAL? Maybe the inode allocbt freespace
record checks aren't quite correct in the backport (like the
original bogus alignment assumption I made).

I'll take a look.

The failing bulkstats, at least the ones I've checked so far, are hitting this path in xfs_bulkstat():

 * Skip if this inode is free.
if (XFS_INOBT_MASK(chunkidx) & irbp->ir_free) {
        lastino = ino;

The backport of the 4 untrusted inode lookup commits looks okay to
me, however I think they depend on commit
7dce11dbac54fce777eea0f5fb25b2694ccd7900 (xfs: always use iget in
bulkstat), which was checked in shortly before the untrusted
inode lookup changes. When that commit is added to the Ubuntu
2.6.32-28 kernel, xfsdump runs fine on the 2 filesystems of mine
that were exhibiting the problem.


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