Date: Mon, 16 Oct 2006 18:54:11 +0200
From: Jan Kara <jack@suse.cz>
To: Eric Sandeen <esandeen@redhat.com>
Cc: Badari Pulavarty <pbadari@us.ibm.com>, Andrew Morton <akpm@osdl.org>,
       Eric Sandeen <sandeen@sandeen.net>, Dave Jones <davej@redhat.com>,
       Linux Kernel <linux-kernel@vger.kernel.org>
Subject: Re: 2.6.18 ext3 panic.
Message-ID: <20061016165411.GI6803@atrey.karlin.mff.cuni.cz>
References: <452CF523.5090708@sandeen.net> <20061011142205.GB24508@atrey.karlin.mff.cuni.cz> <1160589284.1447.19.camel@dyn9047017100.beaverton.ibm.com> <452DAA26.6080200@redhat.com> <20061012122820.GK9495@atrey.karlin.mff.cuni.cz> <20061012094036.e1a3f9f1.akpm@osdl.org> <452EA06F.4060701@redhat.com> <452EB9C5.4000404@us.ibm.com> <20061013075613.GB29170@atrey.karlin.mff.cuni.cz> <452FB9EF.1050109@redhat.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <452FB9EF.1050109@redhat.com>
User-Agent: Mutt/1.5.9i
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 2033
Lines: 43

> Jan Kara wrote:
> 
> >> This is exactly  the solution I proposed earlier (to check 
> >> buffer_mapped() before calling submit_bh()).
> >> But at that time, Jan pointed out that the whole handling is wrong.
> >   Yes, and it was. However it turned out that there are more problems
> > than I thought ;).
> > 
> >> But if this is the only case we need to handle, I am okay with this band 
> >> aid :)
> >   I think Eric's patch may be a part of it. But we still need to check whether
> > the buffer is not after EOF before submitting it (or better said just
> > after we manage to lock the buffer). Because while we are waiting for
> > the buffer lock, journal_unmap_buffer() can still come and steal the
> > buffer - at least the write-out in journal_dirty_data() definitely needs
> > the check if I haven't overlooked something.
> 
> Ok, let me think on that today.  My first reaction is that if we have
> the bh state lock and pay attention to mapped in journal_dirty_data(),
> then any blocks past EOF which have gotten unmapped by
> journal_unmap_buffer will be recognized as such (because they are now
> unmapped... without needing to check for past EOF...) and we'll be fine.
  Hmm, yes, you're right. If we do the test in journal_dirty_data() we
should not file unmapped buffer into transaction's list and hence we
should be safe. Fine. In case we eventually hit the assertion, we can
think further ;).

> As a datapoint, davej's stresstest (several fsx's and fsstresses)
> survived an overnight run on his box, which used to panic in < 2 hrs.
> Survived about 6 hours on my box until I intentionally stopped it; my
> box had added a write/truncate test in a loop, with a bunch of periodic
> syncs as well....
  Perfect :).

								Honza
-- 
Jan Kara <jack@suse.cz>
SuSE CR Labs
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/