linux-ext4 - Re: Bug in delayed allocation: really bad block layouts!

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Message-ID: <20080810182231.GB15353@mit.edu>
Date:	Sun, 10 Aug 2008 14:22:31 -0400
From:	Theodore Tso <tytso@....edu>
To:	Eric Sandeen <sandeen@...hat.com>
Cc:	linux-ext4@...r.kernel.org
Subject: Re: Bug in delayed allocation: really bad block layouts!

On Sun, Aug 10, 2008 at 12:54:00PM -0500, Eric Sandeen wrote:
> 
> Hm, and I tried writing out 10 files in order as a simple test but
> umount/remount brought me back many 0-byte files, I need to update my
> patchset I guess.  :)
> 

One of the questions in my mind is whether this is a regression
triggered by the some of our most recent patches....  since I only
have 2.2% files reported a fragmented by e2fsck, and if this problem
had always been there, I would have expected a much higher
fragmentation number.  So if you have some older kernels, you might
want to see if you can replicate the problem.  I've since found that
just doing a copy via "(tar -cf - -C / usr/include ) | tar -C /mnt -xf -)"
is sufficient to see the problem.  Just add a "sync; sleep 5" before 
the umount.  :-)

							- Ted
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