Date: Tue, 12 Mar 2013 00:12:27 +0100
From: Markus Trippelsdorf <markus@trippelsdorf.de>
To: "Theodore Ts'o" <tytso@mit.edu>, Dave Jones <davej@redhat.com>,
        linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org,
        Zheng Liu <wenqing.lz@taobao.com>
Subject: Re: torrent hash failures since 3.9.0-rc1
Message-ID: <20130311231227.GA319@x4>
References: <20130311171824.GA434@x4>
 <20130311191753.GA439@x4>
 <20130311194159.GB3579@redhat.com>
 <20130311201334.GA444@x4>
 <20130311203738.GB15478@thunk.org>
 <20130311204625.GA433@x4>
 <20130311211833.GC15478@thunk.org>
 <20130311213837.GA438@x4>
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On 2013.03.11 at 22:38 +0100, Markus Trippelsdorf wrote:
> On 2013.03.11 at 17:18 -0400, Theodore Ts'o wrote:
> > On Mon, Mar 11, 2013 at 09:46:25PM +0100, Markus Trippelsdorf wrote:
> > > > BTW, I'm currently running 3.9-rc2 with some additional fixes from the
> > > > ext4 dev branch, and I'm not able to reproduce the problem using
> > > > rtorrent on my laptop.  How reliably is it reproducing for you?  Are
> > > > you seeing the problem every time you try this?
> > > 
> > > Yes, it's 100% reproducible for me. If I boot a 3.8 kernel the issue
> > > vanishes.
> > 
> > Would you be willing to try an experiment? 
> > 
> > Try pulling down the master branch from the ext4 git tree here:
> > 
> > git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4.git
> > 
> > This contains all of the ext4 changes which are in 3.9-rc1, based on
> > top of 3.8-rc3.  See if it reproduces there.  If it does, then it
> > would tend to confirm the hypothesis that the issue was introduced by
> > one of the ext4 patches that we merged during the 3.9-rc1 merge
> > window... and then, since if you can reproduce the problem, if you
> > could do a git bisect to find the guilty commit, that would really
> > greatly appreciated.
> > 
> > If you can't reproduce it from the ext4.git tree, then the problem is
> > probably caused by some other change that was introduced between 3.8
> > and 3.9-rc1.
> 
> I've started a full bisection from v3.8 to todays git tree. It will take
> ~13 steps. However it's already late here in Germany. I will continue
> the bisection tomorrow and report back.

The issue started with:

74cd15cd02708c7188581f279f33a98b2ae8d322 is the first bad commit
commit 74cd15cd02708c7188581f279f33a98b2ae8d322
Author: Zheng Liu <wenqing.lz@taobao.com>
Date:   Mon Feb 18 00:32:55 2013 -0500

    ext4: reclaim extents from extent status tree

Please note that my local rtorrent version was configured with
"--with-posix-fallocate". I'm not sure if distributions also enable this
flag, but it could explain why Ted and Dave weren't able to reproduce
the problem so far.

-- 
Markus
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