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



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


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