linux-ext4 - Re: More ext4 corruption

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Date:	Sat, 4 Apr 2009 12:23:35 -0400
From:	Theodore Tso <tytso@....edu>
To:	Kevin Shanahan <kmshanah@...b.org.au>
Cc:	Eric Sandeen <sandeen@...hat.com>, linux-ext4@...r.kernel.org
Subject: Re: More ext4 corruption

Hmm, what kernel version are you running at this point?  Going through
your old e-mails I saw kernel log from 2.6.29-rc6; is that what you
are still running?

The symptoms seem to be the same as before --- something is writing
garbage into (apparently) a single 4k block, smashing part of your
inode table.  It always seems to be a relatively low-numbered block.
This time, affecting inode numbers in the range of 369-375.  

I don't remember if we've been through this procedure with you yet,
but if you haven't run fsck yet, find out the block number containing
the corrupted part of the inode table:

debugfs /dev/XXX
debugfs: imap <375>
Inode 375 is part of block group 0
      located at block 88, offset 0x0600

And then do extract out the named block number like so:

dd if=/dev/XXX of=block88.dump bs=4k skip=88 count=1

then send us the 4k dump file, and let's see if we can see where it
came from.  Maybe that will be a hint as to who or what wrote the
garbage to that location on disk.

				- Ted
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