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SubjectRe: [RFC] ext3 freeze feature
On Sat, Jan 26, 2008 at 04:35:26PM +1100, David Chinner wrote:
> On Fri, Jan 25, 2008 at 07:59:38PM +0900, Takashi Sato wrote:
> > The points of the implementation are followings.
> > - Add calls of the freeze function (freeze_bdev) and
> > the unfreeze function (thaw_bdev) in ext3_ioctl().
> >
> > - ext3_freeze_timeout() which calls the unfreeze function (thaw_bdev)
> > is registered to the delayed work queue to unfreeze the filesystem
> > automatically after the lapse of the specified time.
> Seems like pointless complexity to me - what happens if a
> timeout occurs while the filsystem is still freezing?
> It's not uncommon for a freeze to take minutes if memory
> is full of dirty data that needs to be flushed out, esp. if
> dm-snap is doing COWs for every write issued....

Sorry, ignore this bit - I just realised the timer is set
up after the freeze has occurred....

Still, that makes it potentially dangerous to whatever is being
done while the filesystem is frozen....


Dave Chinner
Principal Engineer
SGI Australian Software Group

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