linux-ext4 - Re: fsfuzzer: exabyte file sizes

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Message-Id: <7A91398C-F5FF-4A8E-AD44-291B6DFA68A5@dilger.ca>
Date:	Fri, 25 Nov 2011 22:26:17 -0700
From:	Andreas Dilger <adilger@...ger.ca>
To:	Dan Carpenter <dan.carpenter@...cle.com>
Cc:	linux-ext4@...r.kernel.org
Subject: Re: fsfuzzer: exabyte file sizes

On 2011-11-22, at 3:10 AM, Dan Carpenter wrote:
> I'm messing with fsfuzzer and it created a filesystem with a huge
> exabyte file which is larger than ext4 supports.
> 
> root@...on:/tmp# mount -o loop ext4_exabyte_file.img mnt/
> root@...on:/tmp# ls -l mnt/
> ls: cannot access mnt/config.h: Input/output error
> ls: cannot access mnt/configure: Input/output error
> -rw-r--r--     1 root root 9583660007044417438 Nov 21 18:03 config.h.in

I don't know that there is much to be done with this at the ext4 level.
Of course e2fsck should fix this, but that isn't what is being tested here.
I think the best that can be expected of ext4 is that it doesn't crash or
lock up when encountering such files.

It wouldn't be a terrible exercise to run fsfuzzer against some filesystem
and then run e2fsck on it.  It should be able to fix any problem in the
first run, and the filesystem should be totally clean on the second run.

Cheers, Andreas

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