On Thu, Jul 03, 2008 at 09:11:05PM +0900, Takashi Sato wrote: > If the freezer accesses the frozen filesystem and causes a deadlock, > the above ideas can't solve it But you could also say that if the 'freezer' process accesses the frozen filesystem and deadlocks then that's just a bug and that userspace code should be fixed and there's no need to introduce the complexity of a timeout parameter. > >Similarly if a device-mapper device is involved, how should the following > >sequence behave - A, B or C? > > > >1. dmsetup suspend (freezes) > >2. FIFREEZE > >3. FITHAW > >4. dmsetup resume (thaws) > [...] > >C: > > 1 succeeds, freezes > > 2 fails, remains frozen > > 3 fails (because device-mapper owns the freeze/thaw), remains frozen > > 4 succeeds, thaws > > I think C is appropriate and the following change makes it possible. > How do you think? The point I'm trying to make here is: Under what real-world circumstances might multiple concurrent freezing attempts occur, and which of A, B or C (or other variations) would be the most appropriate way of handling such situations? A common example is people running xfs_freeze followed by an lvm command which also attempts to freeze the filesystem. I can see a case for B or C, but personally I prefer A: > > 1 succeeds, freezes > > 2 succeeds, remains frozen > > 3 succeeds, remains frozen > > 4 succeeds, thaws Alasdair -- agk@xxxxxxxxxx -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
