Hi! > On Fri, Nov 10, 2006 at 12:11:46AM +0100, Pavel Machek wrote: > > ? Not sure if I quite understand, but if dm breaks sync... something > > is teribly wrong with dm. And we do simple sys_sync()... so I do not > > think we have a problem. > > If you want to handle arbitrary kernel state, you might have a device-mapper > device somewhere lower down the stack of devices that is queueing any I/O > that reaches it. So anything waiting for I/O completion will wait until > the dm process that suspended that device has finished whatever it is doing > - and that might be a quick thing carried out by a userspace lvm tool, or > a long thing carried out by an administrator using dmsetup. > > I'm guessing you need a way of detecting such state lower down the stack > then optionally either aborting the operation telling the user it can't be > done at present; waiting for however long it takes (perhaps for ever if > the admin disappeared); or more probably skipping those devices on a > 'best endeavours' basis. Okay, so you claim that sys_sync can stall, waiting for administator? In such case we can simply do one sys_sync() before we start freezing userspace... or just more the only sys_sync() there. That way, admin has chance to unlock his system. Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
