[libvirt] [PATCH] snapshot: affect persistent xml after disk snapshot

[Eric Blake]

On 09/16/2011 10:11 PM, Eric Blake wrote:
> For external snapshots to be useful on persistent domains, we must
> alter the persistent definition alongside the running definition.
> Thanks to the possibility of disk hotplug as well as of edits that
> only affect the persistent xml, we can't assume that vm->def and
> vm->newDef have the same disk at the same index, so we can only
> update the persistent copy if the device destination matches up.
>
> * src/qemu/qemu_driver.c (qemuDomainSnapshotCreateDiskActive)
> (qemuDomainSnapshotCreateSingleDiskActive): Also affect newDef, if
> present.
> ---
>
> This is worth including in 0.9.5 - without it, the new feature of
> disk snapshots on a persistent domain are lost the moment the domain
> stops running, which is likely to cause data corruption for guests.

I'm squashing this in, so that the persistent changes are preserved over 
libvirtd restarts.

diff --git i/src/qemu/qemu_driver.c w/src/qemu/qemu_driver.c
index cbe28d8..2a1e5ea 100644
--- i/src/qemu/qemu_driver.c
+++ w/src/qemu/qemu_driver.c
@@ -9221,6 +9221,7 @@ qemuDomainSnapshotCreateDiskActive(virConnectPtr conn,
      bool resume = false;
      int ret = -1;
      int i;
+    bool persist = false;

      if (qemuDomainObjBeginJobWithDriver(driver, vm, QEMU_JOB_MODIFY) < 0)
          return -1;
@@ -9259,8 +9260,10 @@ qemuDomainSnapshotCreateDiskActive(virConnectPtr 
conn,
              int indx = virDomainDiskIndexByName(vm->newDef,
                                                  vm->def->disks[i]->dst,
                                                  false);
-            if (indx >= 0)
+            if (indx >= 0) {
                  persistDisk = vm->newDef->disks[indx];
+                persist = true;
+            }
          }

          ret = qemuDomainSnapshotCreateSingleDiskActive(driver, vm,
@@ -9301,7 +9304,9 @@ cleanup:
      }

      if (vm) {
-        if (virDomainSaveStatus(driver->caps, driver->stateDir, vm) < 0)
+        if (virDomainSaveStatus(driver->caps, driver->stateDir, vm) < 0 ||
+            (persist &&
+             virDomainSaveConfig(driver->configDir, vm->newDef) < 0))
              ret = -1;
          if (qemuDomainObjEndJob(driver, vm) == 0) {
              /* Only possible if a transient vm quit while our locks 
were down,

-- 
Eric Blake   eblake at redhat.com    +1-801-349-2682
Libvirt virtualization library http://libvirt.org