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Date:	Wed, 5 Nov 2008 14:34:25 +0100
From:	Cryptooctoploid <>
To:	"Theodore Tso" <>
Cc:	"Roc Valles" <>,
Subject: Re: data corruption with ext4 (from exposed by rtorrent

On Mon, Nov 3, 2008 at 2:40 PM, Theodore Tso <> wrote:
> On Mon, Nov 03, 2008 at 12:42:11PM +0000, Roc Valles wrote:
>> Some person already reported this. I'm having the same problem.
>> rtorrent is a bittorrent client that makes heavy use of mmap instead
>> of read/write to avoid needless duplication of data. It has exposed
>> other bugs in the past (mmap bug in 2.6.19).
>> Downloading a big torrent (>2GB) with rtorrent triggers it more times
>> than not. The bigger the torrent, the higher the likeliness of
>> failure. When the torrent is finished, if a hash check is forced by
>> pressing control-r on the torrent, some blocks will fail.
> Can both of you send the output of "dumpe2fs -h /dev/<disk device>" of
> the filesystem in question?  The thing which I'm most interested in is
> whether the extents feature was enabled or not.  (i.e., was this a
> freshly made ext4 filesystem, or a ext3 filesystem mounted under ext4,
> and with which features eanbled?)

I tested this further and it turned out that this bug is not extents
related. I get the same hash failures on a partition formatted with:
-O "^extent".

Besides the torrent failures,  ext4 also managed to corrupt two
dspam sqlite3 databases on my system. (After the corruption I
get the following error:
*** glibc detected *** dspam: free(): invalid pointer: 0x0000000001e71c58 ***
======= Backtrace: =========
and the only solution is to restore the database from ext3 backup)

My conclusion is that ext4 is not yet ready for prime time.
I moved all my data back to ext3.
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