linux-ext4 - Re: ext4: (2.6.34-rc4): This should not happen!! Data will be lost

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Message-ID: <20100417223854.GD25507@skl-net.de>
Date:	Sun, 18 Apr 2010 00:38:54 +0200
From:	Andre Noll <maan@...temlinux.org>
To:	Eric Sandeen <sandeen@...hat.com>
Cc:	Bernd Schubert <bernd.schubert@...tmail.fm>,
	Andrew Vasquez <andrew.vasquez@...gic.com>,
	"linux-ext4@...r.kernel.org" <linux-ext4@...r.kernel.org>,
	Linux Driver <Linux-Driver@...gic.com>,
	Thomas Helle <Helle@...bingen.mpg.de>
Subject: Re: ext4: (2.6.34-rc4): This should not happen!!  Data will be lost

On 15:45, Eric Sandeen wrote:
> Interesting that it only happens at enospc time though - the fs would
> be sending barriers in general usage.
> 
> Although, as ext4 fills, it does do more syncing/flushing to try to
> eke out that last bit of space.... hmm....
> 
> Andre, just for fun, you might try mounting -o nodelalloc, fill it again,
> and see if you see the same behavior.

Will do. This will take some time though as I destroyed the fs by
writing directly to the device, so I had to recreate it and start from
scratch. I'm currently filling the new fs using a 60s device timeout as
suggested by Andrew.

> If not, you might do it again w/ defaults, and capture blktrace data, which
> I think will trace barrier requests as well.
> 
> (or, maybe also try testing with -o nobarrier)
> 
> I still don't think it's likely a filesystem problem but maybe you can
> pinpoint the fs behavior that triggers it.

I'll try to reproduce the problem using different timeout values and the
ext4 options you suggest. If I can find a reliable reproducer, I'll run
blktrace and post the results.

Regards
Andre
-- 
The only person who always got his work done by Friday was Robinson Crusoe

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