Re: ext4 lock ordering patch

Jan Kara
2008-05-27T12:13:39Z

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@suse.cz>
SUSE Labs, CR