Re: [libvirt] [PATCH] snapshot: make quiesce a bit safer

On 16.03.2012 21:49, Eric Blake wrote: > If a guest is paused, we were silently ignoring the quiesce flag, > which results in unclean snapshots, contrary to the intent of the > flag. Since we can't quiesce without guest agent support, we should > instead fail if the guest is not running. > > Meanwhile, if we attempt a quiesce command, but the guest agent > doesn't respond, and we time out, we may have left the command > pending on the guest's queue, and when the guest resumes parsing > commands, it will freeze even though our command is no longer > around to issue a thaw. To be safe, we must _always_ pair every > quiesce call with a counterpart thaw, even if the quiesce call > failed due to a timeout, so that if a guest wakes up and starts > processing a command backlog, it will not get stuck in a frozen > state. > > * src/qemu/qemu_driver.c (qemuDomainSnapshotCreateDiskActive): > Always issue thaw after a quiesce, even if quiesce failed. > (qemuDomainSnapshotFSThaw): Add a parameter. > --- > > See also: https://bugzilla.redhat.com/show_bug.cgi?id=804210 > https://www.redhat.com/archives/libvir-list/2012-March/msg00708.html > > src/qemu/qemu_driver.c | 51 +++++++++++++++++++++++++++++++++-------------- > 1 files changed, 36 insertions(+), 15 deletions(-) > ACK this and the follow up patch as well.