The support for incremental backup (not the backup api itself) was gated
on support for migrating bitmaps. As the ability to migrate bitmaps was
added in qemu-6.0 we can now assume that all supported qemu versions
support incremental backup.

Remove the interlocking.

Signed-off-by: Peter Krempa <pkrempa@redhat.com>
---
 src/qemu/qemu_backup.c       | 18 ------------------
 src/qemu/qemu_capabilities.c |  2 +-
 src/qemu/qemu_checkpoint.c   | 12 ------------
 src/qemu/qemu_domain.c       | 11 +----------
 4 files changed, 2 insertions(+), 41 deletions(-)

diff --git a/src/qemu/qemu_backup.c b/src/qemu/qemu_backup.c
index f64639d501..43576d135b 100644
--- a/src/qemu/qemu_backup.c
+++ b/src/qemu/qemu_backup.c
@@ -806,24 +806,6 @@ qemuBackupBegin(virDomainObj *vm,
     if (virDomainBackupAlignDisks(def, vm->def, suffix) < 0)
         goto endjob;

-    if (!virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_INCREMENTAL_BACKUP)) {
-        size_t i;
-
-        if (chkdef) {
-            virReportError(VIR_ERR_OPERATION_UNSUPPORTED, "%s",
-                           _("creating checkpoint for incremental backup is not supported yet"));
-            goto endjob;
-        }
-
-        for (i = 0; i < def->ndisks; i++) {
-            if (def->disks[i].backupmode == VIR_DOMAIN_BACKUP_DISK_BACKUP_MODE_INCREMENTAL) {
-                virReportError(VIR_ERR_OPERATION_UNSUPPORTED, "%s",
-                               _("incremental backup is not supported yet"));
-                goto endjob;
-            }
-        }
-    }
-
     if (priv->backup) {
         virReportError(VIR_ERR_OPERATION_INVALID, "%s",
                        _("another backup job is already running"));
diff --git a/src/qemu/qemu_capabilities.c b/src/qemu/qemu_capabilities.c
index 615efbf021..117648f03f 100644
--- a/src/qemu/qemu_capabilities.c
+++ b/src/qemu/qemu_capabilities.c
@@ -6392,7 +6392,7 @@ static const struct virQEMUCapsDomainFeatureCapabilityTuple domCapsTuples[] = {
     { VIR_DOMAIN_CAPS_FEATURE_VMCOREINFO, QEMU_CAPS_DEVICE_VMCOREINFO },
     { VIR_DOMAIN_CAPS_FEATURE_GENID, QEMU_CAPS_DEVICE_VMGENID },
     { VIR_DOMAIN_CAPS_FEATURE_BACKING_STORE_INPUT, QEMU_CAPS_LAST },
-    { VIR_DOMAIN_CAPS_FEATURE_BACKUP, QEMU_CAPS_INCREMENTAL_BACKUP },
+    { VIR_DOMAIN_CAPS_FEATURE_BACKUP, QEMU_CAPS_LAST },
     { VIR_DOMAIN_CAPS_FEATURE_ASYNC_TEARDOWN, QEMU_CAPS_RUN_WITH_ASYNC_TEARDOWN },
 };

diff --git a/src/qemu/qemu_checkpoint.c b/src/qemu/qemu_checkpoint.c
index b05aaa246e..cf44e45aa1 100644
--- a/src/qemu/qemu_checkpoint.c
+++ b/src/qemu/qemu_checkpoint.c
@@ -588,12 +588,6 @@ qemuCheckpointCreateXML(virDomainPtr domain,
                            _("cannot create checkpoint for inactive domain"));
             return NULL;
         }
-
-        if (!virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_INCREMENTAL_BACKUP)) {
-            virReportError(VIR_ERR_OPERATION_UNSUPPORTED, "%s",
-                           _("incremental backup is not supported yet"));
-            return NULL;
-        }
     }

     if (!(def = virDomainCheckpointDefParseString(xmlDesc, driver->xmlopt,
@@ -855,12 +849,6 @@ qemuCheckpointDelete(virDomainObj *vm,
                            _("cannot delete checkpoint for inactive domain"));
             goto endjob;
         }
-
-        if (!virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_INCREMENTAL_BACKUP)) {
-            virReportError(VIR_ERR_OPERATION_UNSUPPORTED, "%s",
-                           _("incremental backup is not supported yet"));
-            goto endjob;
-        }
     }

     if (!(chk = qemuCheckpointObjFromCheckpoint(vm, checkpoint)))
diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c
index 8be2181156..ea29765c61 100644
--- a/src/qemu/qemu_domain.c
+++ b/src/qemu/qemu_domain.c
@@ -10178,17 +10178,8 @@ qemuDomainDefHasManagedPR(virDomainObj *vm)
  * 0 in case everything is supported.
  */
 int
-qemuDomainSupportsCheckpointsBlockjobs(virDomainObj *vm)
+qemuDomainSupportsCheckpointsBlockjobs(virDomainObj *vm G_GNUC_UNUSED)
 {
-    qemuDomainObjPrivate *priv = vm->privateData;
-
-    if (!virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_INCREMENTAL_BACKUP) &&
-        virDomainListCheckpoints(vm->checkpoints, NULL, NULL, NULL, 0) > 0) {
-        virReportError(VIR_ERR_OPERATION_UNSUPPORTED, "%s",
-                       _("cannot perform block operations while checkpoint exists"));
-        return -1;
-    }
-
     return 0;
 }

-- 
2.48.1