Re: question on freeze and aio

["Rafael J. Wysocki" <rjw@sisk.pl>]

On Tuesday, 13 February 2007 11:17, Pavel Machek wrote:
> Hi!
> 
> > > > can there be running aio requests if all tasks are frozen?
> > > 
> > > Since tasks are frozen, no new aio requests would be submitted. We do a
> > > sync to ssek to complete existing requests; I haven't looked to see
> > > whether that would need extending to flush aio as well, but don't think
> > > that would be the case. Given everyone else's silence, so far, you might
> > > be better to ask the author(s) of the aio code.
> > 
> > I believe Nigel is basically correct.  However sync will only flush aio 
> > for block devices.  Other types of aio will remain active.
> > 
> > aio callbacks are interrupt-driven and execute in a workqueue (see
> > fs/aio.c), and as far as I can tell that workqueue doesn't freeze.  
> > Unless some general facility freezes all workqueues...
> 
> If this is so... we need to make that particular workqueue
> freezeable. (And we should really make most workqueues freezeable).

Except for the ones that are needed to save the image.  Do we know which
ones they are?

Rafael