On Wed, Aug 24, 2011 at 09:22:20AM -0600, Eric Blake wrote:
> qemuDomainSnapshotRevertInactive has the same FIXMEs as
> qemuDomainSnapshotCreateInactive, so algorithmic fixes to properly
> handle partial loop iterations should be applied later to both
> functions, but we're not making the situation any worse in
> this patch.
>
> * src/qemu/qemu_driver.c (qemuDomainRevertToSnapshot): Use
> qemu-img rather than 'qemu -loadvm' to revert to offline snapshot.
> (qemuDomainSnapshotRevertInactive): New helper.
> ---
> src/qemu/qemu_driver.c | 65 +++++++++++++++++++++++++++++++++++++++++------
> 1 files changed, 56 insertions(+), 9 deletions(-)
>
> diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
> index 7950aff..1caa870 100644
> --- a/src/qemu/qemu_driver.c
> +++ b/src/qemu/qemu_driver.c
> @@ -8738,6 +8738,52 @@ cleanup:
> return xml;
> }
>
> +/* The domain is expected to be locked and inactive. */
> +static int
> +qemuDomainSnapshotRevertInactive(virDomainObjPtr vm,
> + virDomainSnapshotObjPtr snap)
> +{
> + const char *qemuimgarg[] = { NULL, "snapshot", "-a", NULL, NULL, NULL };
> + int ret = -1;
> + int i;
> +
> + qemuimgarg[0] = qemuFindQemuImgBinary();
> + if (qemuimgarg[0] == NULL) {
> + /* qemuFindQemuImgBinary set the error */
> + goto cleanup;
> + }
> +
> + qemuimgarg[3] = snap->def->name;
> +
> + for (i = 0; i < vm->def->ndisks; i++) {
> + /* FIXME: we also need to handle LVM here */
> + /* FIXME: if we fail halfway through this loop, we are in an
> + * inconsistent state. I'm not quite sure what to do about that
> + */
> + if (vm->def->disks[i]->device == VIR_DOMAIN_DISK_DEVICE_DISK) {
> + if (!vm->def->disks[i]->driverType ||
> + STRNEQ(vm->def->disks[i]->driverType, "qcow2")) {
> + qemuReportError(VIR_ERR_OPERATION_INVALID,
> + _("Disk device '%s' does not support"
> + " snapshotting"),
> + vm->def->disks[i]->info.alias);
> + goto cleanup;
> + }
> +
> + qemuimgarg[4] = vm->def->disks[i]->src;
> +
> + if (virRun(qemuimgarg, NULL) < 0)
> + goto cleanup;
> + }
> + }
> +
> + ret = 0;
> +
> +cleanup:
> + VIR_FREE(qemuimgarg[0]);
> + return ret;
> +}
I know that virRun is implemented in terms of virCommand, but should
be we aiming to convert virRun uses over to directly use virCommand ?
> @@ -8844,14 +8890,9 @@ static int qemuDomainRevertToSnapshot(virDomainSnapshotPtr snapshot,
> VIR_DOMAIN_EVENT_STARTED_FROM_SNAPSHOT);
> }
> } else {
> - /* qemu is a little funny with running guests and the restoration
> - * of snapshots. If the snapshot was taken online,
> - * then after a "loadvm" monitor command, the VM is set running
> - * again. If the snapshot was taken offline, then after a "loadvm"
> - * monitor command the VM is left paused. Unpausing it leads to
> - * the memory state *before* the loadvm with the disk *after* the
> - * loadvm, which obviously is bound to corrupt something.
> - * Therefore we destroy the domain and set it to "off" in this case.
> + /* Newer qemu -loadvm refuses to revert to the state of a snapshot
> + * created by qemu-img snapshot -c. If the domain is running, we
> + * must take it offline; then do the revert using qemu-img.
> */
>
> if (virDomainObjIsActive(vm)) {
> @@ -8861,6 +8902,12 @@ static int qemuDomainRevertToSnapshot(virDomainSnapshotPtr snapshot,
> VIR_DOMAIN_EVENT_STOPPED,
> VIR_DOMAIN_EVENT_STOPPED_FROM_SNAPSHOT);
> if (!vm->persistent) {
> + /* XXX it should be impossible to create an offline snapshot
> + * of a transient domain. Once we fix 'undefine' to convert
> + * a defined domain back to transient, that transition should
> + * be rejected if any offline snapshots exist. For now, we
> + * just stop the transient domain and quit, without reverting
> + * any disk state. */
> if (qemuDomainObjEndJob(driver, vm) > 0)
> virDomainRemoveInactive(&driver->domains, vm);
> vm = NULL;
> @@ -8868,7 +8915,7 @@ static int qemuDomainRevertToSnapshot(virDomainSnapshotPtr snapshot,
> }
> }
>
> - if (qemuDomainSnapshotSetCurrentActive(vm, driver->snapshotDir) < 0)
> + if (qemuDomainSnapshotRevertInactive(vm, snap) < 0)
> goto endjob;
> }
>
ACK
Daniel
--
|: http://berrange.com -o- http://www.flickr.com/photos/dberrange/ :|
|: http://libvirt.org -o- http://virt-manager.org :|
|: http://autobuild.org -o- http://search.cpan.org/~danberr/ :|
|: http://entangle-photo.org -o- http://live.gnome.org/gtk-vnc :|
--
libvir-list mailing list
libvir-list@xxxxxxxxxx
https://www.redhat.com/mailman/listinfo/libvir-list