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Re: [PATCH] Freeze bdevs when freezing processes.

To: Christoph Hellwig <hch@xxxxxxxxxxxxx>, "Rafael J. Wysocki" <rjw@xxxxxxx>, David Chinner <dgc@xxxxxxx>, Nigel Cunningham <ncunningham@xxxxxxxxxxxxx>, Andrew Morton <akpm@xxxxxxxx>, LKML <linux-kernel@xxxxxxxxxxxxxxx>, xfs@xxxxxxxxxxx
Subject: Re: [PATCH] Freeze bdevs when freezing processes.
From: Pavel Machek <pavel@xxxxxx>
Date: Tue, 24 Oct 2006 23:26:48 +0200
In-reply-to: <20061024170633.GA17956@xxxxxxxxxxxxx>
References: <1161576735.3466.7.camel@xxxxxxxxxxxxxxxxxx> <200610231236.54317.rjw@xxxxxxx> <20061024144446.GD11034@xxxxxxxxxxxxxxxxx> <200610241730.00488.rjw@xxxxxxx> <20061024170633.GA17956@xxxxxxxxxxxxx>
Sender: xfs-bounce@xxxxxxxxxxx
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Hi!

On Tue 2006-10-24 18:06:33, Christoph Hellwig wrote:
> On Tue, Oct 24, 2006 at 05:29:59PM +0200, Rafael J. Wysocki wrote:
> > Do you mean calling sys_sync() after the userspace has been frozen
> > may not be sufficient?
> 
> No, that's definitly not enough.  You need to freeze_bdev to make sure
> data is on disk in the place it's expected by the filesystem without
> starting a log recovery.

I believe log recovery is okay in this case.

It can only happen when kernel dies during suspend or during
resume... And log recovery seems okay in that case. We even guarantee
that user did not loose any data -- by using sys_sync() after userland
is stopped -- but let's not overdo over protections.
                                                                Pavel

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) 
http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html


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