[dm-devel] Re: [PATCH 2.6.19 5/5] fs: freeze_bdev with semaphore not mutex

[Pavel Machek]

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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