kvm: suspend a VM before snapshot deletion (see PR apache#3193) (apache#3194)

To make sure that a qemu2-image won't be corrupted by the snapshot deletion procedure which is being performed after copying the snapshot to a secondary store, I'd propose to put a VM in to suspended state.

Additional reference: https://bugzilla.redhat.com/show_bug.cgi?id=920020#c5

Fixes apache#3193

Author: Vladimir Melnik

plugins/hypervisors/kvm/src/com/cloud/hypervisor/kvm/storage/KVMStorageProcessor.java

@@ -996,6 +996,12 @@ public Answer backupSnapshot(final CopyCommand cmd) {
                             primaryStore.getUuid());
                     if (state == DomainInfo.DomainState.VIR_DOMAIN_RUNNING && !primaryStorage.isExternalSnapshot()) {
                         final DomainSnapshot snap = vm.snapshotLookupByName(snapshotName);
+                        try {
+                            vm.suspend();
+                        } catch(final Exception e) {
+                            s_logger.debug("Failed to suspend the VM: " + e);
+                            throw e;
+                        }
                         snap.delete(0);
 
                         /*

ui/l10n/en.js

@@ -1922,7 +1922,7 @@ var dictionary = {"ICMP.code":"ICMP Code",
 "message.action.take.snapshot":"Please confirm that you want to take a snapshot of this volume.",
 "message.action.unmanage.cluster":"Please confirm that you want to unmanage the cluster.",
 "message.action.vmsnapshot.create":"Please confirm that you want to take a snapshot of this instance. <br>Please notice that the instance will be paused during the snapshoting, and resumed after snapshotting, if it runs on KVM.",
-"message.action.vmsnapshot.delete":"Please confirm that you want to delete this VM snapshot.",
+"message.action.vmsnapshot.delete":"Please confirm that you want to delete this VM snapshot. <br>Please notice that the instance will be paused before the snapshot deletion, and resumed after deletion, if it runs on KVM.",
 "message.action.vmsnapshot.revert":"Revert VM snapshot",
 "message.activate.project":"Are you sure you want to activate this project?",
 "message.add.VPN.gateway":"Please confirm that you want to add a VPN Gateway",