Re: question on freeze and aio

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

On Friday, 9 February 2007 23:03, Alan Stern wrote:
> On Sat, 10 Feb 2007, Nigel Cunningham wrote:
> 
> > Hi.
> > 
> > On Fri, 2007-02-09 at 17:04 +0100, Oliver Neukum 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...

No, workqueues are not frozen unless they are explicitly declared as
freezeable.  Which currently is only done by XFS, AFAIKS.

Greetings,
Rafael


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