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Date: Fri, 1 Apr 2016 10:44:19 +0200
From: David Sterba <dsterba@suse.cz>
To: Qu Wenruo <quwenruo@cn.fujitsu.com>
Cc: linux-btrfs@vger.kernel.org
Subject: Re: [PATCH] btrfs-progs: fsck: Fix a false metadata extent warning
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On Fri, Apr 01, 2016 at 08:28:18AM +0800, Qu Wenruo wrote:
> 
> 
> David Sterba wrote on 2016/03/31 18:30 +0200:
> > On Thu, Mar 31, 2016 at 10:19:34AM +0800, Qu Wenruo wrote:
> >> At least 2 user from mail list reported btrfsck reported false alert of
> >> "bad metadata [XXXX,YYYY) crossing stripe boundary".
> >>
> >> While the reported number are all inside the same 64K boundary.
> >> After some check, all the false alert have the same bytenr feature,
> >> which can be divided by stripe size (64K).
> >>
> >> The result seems to be initial 'max_size' can be 0, causing 'start' +
> >> 'max_size' - 1, to cross the stripe boundary.
> >>
> >> Fix it by always update extent_record->cross_stripe when the
> >> extent_record is updated, to avoid temporary false alert to be reported.
> >>
> >> Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
> >
> > Applied, thanks.
> >
> > Do you have a test image for that?
> >
> >
> Unfortunately, no.
> 
> Although I figured out the cause the the false alert, I still didn't 
> find a image/method to reproduce it, except the images of reporters.
> 
> I can dig a little further trying to make a image.

After another look, why don't we use nodesize directly? Or stripesize
where applies. With max_size == 0 the test does not make sense, we ought
to know the alignment.