From: Eric Sandeen <sandeen@redhat.com>
Subject: Re: fio test triggering bad data on ext4
Date: Fri, 18 Jun 2010 09:59:13 -0500
Message-ID: <4C1B89C1.6090408@redhat.com>
References: <4C1B292C.2080205@fusionio.com> <4C1B7C73.505@redhat.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: 7bit
Cc: tytso@mit.edu, adilger@sun.com, linux-ext4@vger.kernel.org
To: Jens Axboe <jaxboe@fusionio.com>
In-Reply-To: <4C1B7C73.505@redhat.com>
Sender: linux-ext4-owner@vger.kernel.org

Eric Sandeen wrote:
> Jens Axboe wrote:
>> Hi,
>>
>> I was writing a small fio job file to do writes and read verifies on a
>> device. It forks 32 processes, each writing randomly to 4 files with a
>> block size between 4k and 16k. When it has written 1024 of those blocks,
>> it'll verify the oldest 512 of them. Each block is checksummed for every
>> 512b. It uses libaio and O_DIRECT.
>>
>> It works on ext2 and btrfs. I haven't run it to completion yet, but they
>> survive 15-20 minutes just fine. ext4 doesn't even go a full minutes
>> before this triggers:
> 
> Jens, can you try XFS too?  Since ext3 can't do direct IO to a hole,
> (and I'm not sure about btrfs in that regard), ext4 may be most similar
> to xfs's behavior on the test ... wondering how it fares.
> 
> Thanks,
> -Eric

Actually mingming had a patch for direct-io.c which may be related, I'll
test that out.

-Eric