linux-ext4 - Re: ext4 lock ordering patch

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Date:	Tue, 27 May 2008 14:13:37 +0200
From:	Jan Kara <jack@...e.cz>
To:	"Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>
Cc:	cmm@...ibm.com, linux-ext4@...r.kernel.org
Subject: Re: ext4 lock ordering patch

On Mon 26-05-08 23:21:09, Aneesh Kumar K.V wrote:
> On Mon, May 26, 2008 at 07:34:52PM +0200, Jan Kara wrote:
> >   Hi Mingming,
> > 
> >   I've noticed you removed the patch reversing locking order of page lock
> > and transaction start from ext4 patch queue. Was this because of that
> > reported performance problem or for some other reason? As far as I've
> > understood that problem has been just in the patch fixing the delalloc mode
> > part so just removing that patch would be enough AFAICT.
> >   Anyway, the problem is I have now ordered mode rewrite for JBD2/ext4
> > which depends on this patch so the question is how to proceed... Should we
> > first fix that delalloc problem (are you looking into that?) or do we merge
> > all the changes and then fixup the delalloc code?
> > 
> That was due to delalloc interaction with locking order change patches.
  What kind of interaction do you mean? My patch actually didn't handle
delalloc at all - Mingming had a patch to workaround that.

> I am right now testing some changes for delalloc. But I still have file
> system hang with fsstress. So I haven't posted the latest changes yet.
  OK and do these changes count with reversion of the locking order or
not? Because my feeling when I last looked at delalloc was that with the
lock-ordering reversed it would be better to do da_writepages() and similar
stuff differently...
								Honza
-- 
Jan Kara <jack@...e.cz>
SUSE Labs, CR
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