[dm-devel] Re: [PATCH 2.6.19 5/5] fs: freeze_bdev with semaphore not mutex
Rafael J. Wysocki
rjw at sisk.pl
Thu Nov 9 15:52:33 UTC 2006
Hi,
On Wednesday, 8 November 2006 19:09, Pavel Machek wrote:
> Hi!
>
> > > swsusp-freeze-filesystems-during-suspend-rev-2.patch
> > >
> > > I think you need to give more thought to device-mapper
> > > interactions here. If an underlying device is suspended
> > > by device-mapper without freezing the filesystem (the
> > > normal state) and you issue a freeze_bdev on a device
> > > above it, the freeze_bdev may never return if it attempts
> > > any synchronous I/O (as it should).
> >
> > Well, it looks like the interactions with dm add quite a bit of
> > complexity here.
>
> What about just fixing xfs (thou shall not write to disk when kernel
> threads are frozen), and getting rid of blockdev freezing?
Well, first I must admit you were absolutely right being suspicious with
respect to this stuff.
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?
Rafael
--
You never change things by fighting the existing reality.
R. Buckminster Fuller
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