Re: What happened to data=guarded?

From: Jan Kara
Date: Tue Aug 11 2009 - 11:34:34 EST


> Frans Pop <elendil@xxxxxxxxx> writes:
>
> > On Tuesday 11 August 2009, Chris Mason wrote:
> >> On Tue, Aug 11, 2009 at 03:35:36PM +0200, Frans Pop wrote:
> >> > Somewhat unrelated, but what happened to the data=guarded patches
> >> > Chris Mason proposed back in April?
> >>
> >> I missed 2.6.31 but plan on sending for 2.6.32. I promised to send
> >> along a forward port of the patches a while back, but I finally have
> >> one in testing here. It should go out shortly.
> >
> > Good to hear. I've so far stayed with data=ordered as I think I'd prefer
> > data=guarded over data=writeback. I'll certainly give it a try when it's
> > available.
>
> Same here. data=writeback already cost me a few files after crashes here :/
In this regard, data=guarded need not be better than data=writeback.
We push out the data in guarded mode as late as in writeback mode
(that's where the performance benefit comes from ;). The difference is
that we increase i_size only after data are safely on disk so we cannot
expose old data.
So security-wise, guarded mode is as safe as ordered mode but in other
aspects its more like data=writeback.

Honza
--
Jan Kara <jack@xxxxxxx>
SuSE CR Labs
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