Date:	Tue, 27 Nov 2012 18:40:53 +0000
From:	Adam Huffman <adam.huffman@...il.com>
To:	"Theodore Ts'o" <tytso@....edu>
Cc:	linux-ext4 <linux-ext4@...r.kernel.org>
Subject: Re: Filesystem corruption on Fedora 17

On Tue, Nov 27, 2012 at 5:31 PM, Theodore Ts'o <tytso@....edu> wrote:
> On Tue, Nov 27, 2012 at 04:59:05PM +0000, Adam Huffman wrote:
>>
>> I took a copy using dd_rescue yesterday, and that's what I've been
>> running fsck against.
>> (After that I tried mkfs.ext4 -S on the disk itself, which wasn't successful...)
>
> On the disk itself?  Instead of another copy of the disk?  That was
> unfortunate.... mke2fs -S is very destructive when it doesn't work
> out.... and what happened after you tried that, BTW?  What were the

It's fair to say I was desperate at that point...

Effectively, that filesystem was wiped.

> e2fsck failures that you were seeing?  If you're seeing the same
> repeated journal failures, you might as well go for broke and see if
> zapping the journal helps:
>
>         debugfs -w /dev/XXXX -R "clri <8>"
>
> Again, I always recommend issuing these sorts of commands on copies,
> and to never tamper with the initial image backup of the file
> system....
>

Indeed.

>> The images comprises an LVM PV and VG, so I've used kpartx to make it
>> available, if that makes a difference.
>>
>> There is one person claiming that it does:
>>
>> http://j-b.livejournal.com/334065.html
>
> Hmm... I don't see why that would make a difference.  At this point
> what I'd really need is an e2image dump of the file system.  Please
> read the e2image man page, especially the sections regarding a raw
> e2image dump and a qcow e2image dump.  If you are willing to send me a
> copy of your metadata blocks, please send me a qcow e2image dump and
> I'll take a look at it.
>
>> Do you have any ideas about this error, with a different LV from the same disk?:
>>
>> Pass 1: Checking inodes, blocks, and sizes
>> Inode 4122234 has illegal block(s).  Clear? yes
>>
>> Illegal block #256918621 (1313286244) in inode 4122234.  CLEARED.
>> Error storing directory block information (inode=4122234, block=0,
>> num=78646612): Memory allocation failed
>
> That's the sign of a very badly corrupted inode data structure.  We
> should do a better job of handling this case automatically.
>
> Can you send me a copy of the output of:
>
> debugfs -w /dev/XXXX
> debugfs: stat <4122234>
>
> Then what I'd recommend doing is to use the debugfs command "clri
> <4122234>" to zap the the corrupted inode, and then rerunning e2fsck.
> This is relatively safe thing to try as these things go, so I won't
> strongly recommend that you take an image backup of the file system
> image in question before proceeding --- but in general, it's still a
> good idea if you are paranoid.  :-)
>
> The fact that you are seeing multiple errors like this really makes me
> wonder.... what kind of storage device is this?  An external USB
> drive?  A SATA drive?  A software raid device?  Something else?
>

I tried to mount the image once more, and this time it worked.  There
were system log errors about a specific inode, but everything else
copied to a different disk intact.  Hence I'll try to get the machine
back up and running.  Once I've done that, I'll send you the
information and files you asked for, if you're still interested.

Thanks again,
Adam
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