linux-kernel - Re: 2.6.19 file content corruption on ext3

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Date:	Tue, 19 Dec 2006 04:04:02 +0200
From:	Andrei Popa <andrei.popa@...eo.ro>
To:	Andrew Morton <akpm@...l.org>
Cc:	Linus Torvalds <torvalds@...l.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Hugh Dickins <hugh@...itas.com>,
	Florian Weimer <fw@...eb.enyo.de>,
	Marc Haber <mh+linux-kernel@...schlus.de>,
	Martin Michlmayr <tbm@...ius.com>
Subject: Re: 2.6.19 file content corruption on ext3


> > > If all of test_clear_page_dirty() has been commented out then the page will
> > > never become clean hence will never fall out of pagecache, so unless Andrei
> > > is doing a reboot before checking for corruption, perhaps the underlying
> > > data on-disk is incorrect, but we can't see it.
> > 
> > if I do a sync and echo 1 > /proc/sys/vm/drop_caches
> 
> OK, that works.
> 
> >  does the reboot is
> > still necesary ?
> 
> It might be necessary to reboot in this case - if we're leaving the
> pagecache dirty, writing to drop_caches won't remove it.  And you probably
> won't be able to get a clean reboot either.
> 
> > > 
> > > Andrei, how _are_ you running this test?    What's the exact sequence of steps?
> > > 
> > > In particular, are you doing anything which would cause the corrupted file
> > > to be evicted from memory, thus forcing a read from disk?  Such as
> > > unmounting and then remounting the filesystem?
> > 
> > I boot linux, I start rtorrent and start the download, while it's
> > downloading I start evolution and i check my mail(my mbox is very large,
> > several hundered megabytes), I close evolution(I use evolution just to
> > have another application witch uses the filesystem and the memory), I
> > start evolution again. I start firefox. The download is complete.
> > Rtorrent says if the hash is good or not. I do a "unrar t qwe.rar" to
> > test that all 84 downloaded rar files are ok and see the result.
> > 
> > > 
> > > The point of my question is to check that the data is really incorrect
> > > on-disk, or whether it is incorrect in pagecache.

I rebooted and the files are still broken after reboot(tested twice) so
the data is incorrect on disk.

> > > 
> > > Also, it'd be useful if you could determine whether the bug appears with
> > > the ext2 filesystem: do s/ext3/ext2/ in /etc/fstab, or boot with
> > > rootfstype=ext2 if it's the root filesystem.
> > 
> > I will test.

Will test In a couple of hours, I have some work to do...

> 
> ok, thanks.

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