[libvirt PATCH 15/20] qemu_snapshot: delete: properly update parent snapshot with revert data

[Pavel Hrdina]

When deleting external snapshot and parent snapshot is the currently
active snapshot as user reverted to it we need to properly update the
parent snapshot metadata.

After the delete is done the new overlay files will be the currently
used files created when snapshot revert was done, replacing the original
overlay files.

Signed-off-by: Pavel Hrdina <phrdina at redhat.com>
---
 src/qemu/qemu_snapshot.c | 40 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 40 insertions(+)

diff --git a/src/qemu/qemu_snapshot.c b/src/qemu/qemu_snapshot.c
index dbcdf56758..513bcb5a86 100644
--- a/src/qemu/qemu_snapshot.c
+++ b/src/qemu/qemu_snapshot.c
@@ -3063,6 +3063,41 @@ qemuSnapshotDiscardExternal(virDomainObj *vm,
 }
 
 
+static int
+qemuSnapshotDeleteUpdateParent(virDomainObj *vm,
+                               virDomainMomentObj *parent)
+{
+    size_t i;
+    virQEMUDriver *driver = ((qemuDomainObjPrivate *) vm->privateData)->driver;
+    g_autoptr(virQEMUDriverConfig) cfg = virQEMUDriverGetConfig(driver);
+    virDomainSnapshotDef *parentDef = virDomainSnapshotObjGetDef(parent);
+
+    if (!parentDef)
+        return 0;
+
+    if (!parentDef->revertdisks)
+        return 0;
+
+    for (i = 0; i < parentDef->ndisks; i++) {
+        virDomainSnapshotDiskDefClear(&parentDef->disks[i]);
+    }
+    g_free(parentDef->disks);
+
+    parentDef->disks = g_steal_pointer(&parentDef->revertdisks);
+    parentDef->ndisks = parentDef->nrevertdisks;
+    parentDef->nrevertdisks = 0;
+
+    if (qemuDomainSnapshotWriteMetadata(vm,
+                                        parent,
+                                        driver->xmlopt,
+                                        cfg->snapshotDir) < 0) {
+        return -1;
+    }
+
+    return 0;
+}
+
+
 static int
 qemuSnapshotDiscardMetadata(virDomainObj *vm,
                             virDomainMomentObj *snap,
@@ -3102,6 +3137,11 @@ qemuSnapshotDiscardMetadata(virDomainObj *vm,
         virDomainMomentMoveChildren(snap, snap->parent);
     }
 
+    if (update_parent && snap->parent) {
+        if (qemuSnapshotDeleteUpdateParent(vm, snap->parent) < 0)
+            ret = -1;
+    }
+
     snapFile = g_strdup_printf("%s/%s/%s.xml", cfg->snapshotDir, vm->def->name,
                                snap->def->name);
 
-- 
2.39.2