qemu: checkpoint: Forbid creating checkpoints until we support backups

Checkpoints by themselves are not very useful for anything else than
testing the few bitmap interactions that are currently implemented.

It's very unlikely that anybody used this feature and thus we can
disable it until we have a more complete implementation ready.

Additionally the code for deleting checkpoints has many broken failure
scenarios which should be fixed first. This will require support of
deleting a bitmap in a qemu 'transaction' which was not released yet.

Curious users obviously can use the qemu namespace in the XML to enable
this for experiments:

  <domain type='kvm' xmlns:qemu='http://libvirt.org/schemas/domain/qemu/1.0'>
    ...
    <qemu:capabilities>
      <qemu:add capability='incremental-backup'/>
    </qemu:capabilities>
  </domain>

Signed-off-by: Peter Krempa <pkrempa@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>

diff --git a/src/qemu/qemu_checkpoint.c b/src/qemu/qemu_checkpoint.c
index 60ac8fff0d70f44c17d37c65b710621eb5c6f77d..ac6328afa9aef60ec7d18ca1900c2c5a29f0dd68 100644 (file)
--- a/src/qemu/qemu_checkpoint.c
+++ b/src/qemu/qemu_checkpoint.c
@@ -383,9 +383,9 @@ qemuCheckpointCreateXML(virDomainPtr domain,
         return NULL;
     }
 
-    if (!virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_BITMAP_MERGE)) {
-        virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
-                       _("qemu binary lacks persistent bitmaps support"));
+    if (!virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_INCREMENTAL_BACKUP)) {
+        virReportError(VIR_ERR_OPERATION_UNSUPPORTED, "%s",
+                       _("incremental backup is not supported yet"));
         return NULL;
     }
 
@@ -570,14 +570,15 @@ qemuCheckpointDelete(virDomainObjPtr vm,
         return -1;
 
     if (!metadata_only) {
-        if (!virDomainObjIsActive(vm)) {
+        if (!virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_INCREMENTAL_BACKUP)) {
             virReportError(VIR_ERR_OPERATION_UNSUPPORTED, "%s",
-                           _("cannot delete checkpoint for inactive domain"));
+                           _("incremental backup is not supported yet"));
             goto endjob;
         }
-        if (!virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_BITMAP_MERGE)) {
-            virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
-                           _("qemu binary lacks persistent bitmaps support"));
+
+        if (!virDomainObjIsActive(vm)) {
+            virReportError(VIR_ERR_OPERATION_UNSUPPORTED, "%s",
+                           _("cannot delete checkpoint for inactive domain"));
             goto endjob;
         }
     }