Re: torrent hash failures since 3.9.0-rc1

From: Markus Trippelsdorf
Date: Mon Mar 11 2013 - 19:12:35 EST


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@xxxxxxxxxx>
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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