qemu: snapshot: Don't attempt to resume cpus if they were not paused

External disk-only snapshots with recent enough qemu don't require
libvirt to pause the VM. The logic determining when to resume cpus was
slightly flawed and attempted to resume them even if they were not
paused by the snapshot code. This normally was not a problem, but with
locking enabled the code would attempt to acquire the lock twice.

The fallout of this bug would be a error from the API, but the actual
snapshot being created. The bug was introduced with when adding support
for external snapshots with memory (checkpoints) in commit f569b87.

Resolves problems described by:
https://bugzilla.redhat.com/show_bug.cgi?id=1403691

diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index ea44f1f39200d58c4020e3ccbf61113f21e036bf..8dc318a3884f956daea2881c0dc7d79e1e59786d 100644 (file)
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -14472,8 +14472,6 @@ qemuDomainSnapshotCreateActiveExternal(virConnectPtr conn,
     if (virDomainObjGetState(vm, NULL) == VIR_DOMAIN_PMSUSPENDED) {
         pmsuspended = true;
     } else if (virDomainObjGetState(vm, NULL) == VIR_DOMAIN_RUNNING) {
-        resume = true;
-
         /* For external checkpoints (those with memory), the guest
          * must pause (either by libvirt up front, or by qemu after
          * _LIVE converges).  For disk-only snapshots with multiple
@@ -14496,6 +14494,8 @@ qemuDomainSnapshotCreateActiveExternal(virConnectPtr conn,
                                _("guest unexpectedly quit"));
                 goto cleanup;
             }
+
+            resume = true;
         }
     }