On 11/19/2012 09:06 AM, Peter Krempa wrote:
Some hypervisors require a respawn of the hypervisor to allow reverting to some snapshot states. This patch adds flag to remove the default safe approach to not allow this. When this flag is specified the hypervisor driver should re-emit events to allow management apps to reconnect.
This flag is meant as a lesser way to enforce the restart of the hypervisor, that is a fairly common possibility compared to other meanings that the existing force flag has. --- Force now selects this flag and this flag can be used with internal snapshots too. ---
@@ -12129,7 +12129,11 @@ static int qemuDomainRevertToSnapshot(virDomainSnapshotPtr snapshot,
virCheckFlags(VIR_DOMAIN_SNAPSHOT_REVERT_RUNNING | VIR_DOMAIN_SNAPSHOT_REVERT_PAUSED | - VIR_DOMAIN_SNAPSHOT_REVERT_FORCE, -1); + VIR_DOMAIN_SNAPSHOT_REVERT_FORCE | + VIR_DOMAIN_SNAPSHOT_REVERT_RESPAWN, -1); + + if (flags & VIR_DOMAIN_SNAPSHOT_REVERT_FORCE) + flags |= VIR_DOMAIN_SNAPSHOT_REVERT_RESPAWN;
Up to here looks fine.
/* We have the following transitions, which create the following events: * 1. inactive -> inactive: none @@ -12249,7 +12253,7 @@ static int qemuDomainRevertToSnapshot(virDomainSnapshotPtr snapshot,
Hmm, this is incomplete. Earlier, inside a VIR_DOMAIN_SNAPSHOT_REVERT_FORCE check, we have: if (virDomainObjIsActive(vm) && !(snap->def->state == VIR_DOMAIN_RUNNING || snap->def->state == VIR_DOMAIN_PAUSED) && (flags & (VIR_DOMAIN_SNAPSHOT_REVERT_RUNNING | VIR_DOMAIN_SNAPSHOT_REVERT_PAUSED))) { virReportError(VIR_ERR_SNAPSHOT_REVERT_RISKY, "%s", _("must respawn qemu to start inactive snapshot")); goto cleanup; which should be converted to the new flag.
if (config && !virDomainDefCheckABIStability(vm->def, config)) { virErrorPtr err = virGetLastError();
- if (!(flags & VIR_DOMAIN_SNAPSHOT_REVERT_FORCE)) { + if (!(flags & VIR_DOMAIN_SNAPSHOT_REVERT_RESPAWN)) { /* Re-spawn error using correct category. */
I think this one is correct, though.
@@ -2830,6 +2830,10 @@ I<--running> or I<--paused> flags when reverting to a disk snapshot of a transient domain. The I<--stopped> flag cannot be used on snapshots of transient domains.
+Some snapshot revert approaches may require a respawn of the hypervisor +process. This is not allowed by default. You may specify I<--allow-respawn> +to override this limit.
It might be worth mentioning that --force implies --allow-respawn (that is, --force is a supserset of --allow-respawn, in that it can force situations that --allow-respawn will not). -- Eric Blake eblake@redhat.com +1-919-301-3266 Libvirt virtualization library http://libvirt.org