linux-kernel - Re: [PATCH 2.6.19 5/5] fs: freeze

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Message-ID: <20061110103835.GF3196@elf.ucw.cz>
Date:	Fri, 10 Nov 2006 11:38:35 +0100
From:	Pavel Machek <pavel@....cz>
To:	David Chinner <dgc@....com>
Cc:	"Rafael J. Wysocki" <rjw@...k.pl>,
	Alasdair G Kergon <agk@...hat.com>,
	Eric Sandeen <sandeen@...hat.com>,
	Andrew Morton <akpm@...l.org>, linux-kernel@...r.kernel.org,
	dm-devel@...hat.com, Srinivasa DS <srinivasa@...ibm.com>,
	Nigel Cunningham <nigel@...pend2.net>
Subject: Re: [PATCH 2.6.19 5/5] fs: freeze_bdev with semaphore not mutex

Hi!

> > > OTOH I have no idea _how_ we can tell xfs that the processes have been
> > > frozen.  Should we introduce a global flag for that or something?
> > 
> > I guess XFS should just do all the writes from process context, and
> > refuse any writing when its threads are frozen... I actually still
> > believe it is doing the right thing, because you can't really write to
> > disk from timer.
> 
> As per the recent thread about this, XFS threads suspend correctly
> and XFS doesn't issue I/O from timers.
> 
> The problem appears to be per-cpu workqueues that don't get
> suspended because suspend does not shut down workqueue threads. You

Workqueues should be easy to handle. current->flags &= ~PF_NONFREEZE,
and problem should be solved.
								Pavel

-- 
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