qemuDomainBlockCommit: Move checks depending on capabilities after liveness check

Since capabilities are not present for inactive VMs we'd report that we
don't support '--delete' or committing while checkpoints exist rather
than the proper error.
Signed-off-by: NPeter Krempa <pkrempa@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>

src/qemu/qemu_driver.c

@@ -18413,9 +18413,6 @@ qemuDomainBlockCommit(virDomainPtr dom,
     if (virDomainBlockCommitEnsureACL(dom->conn, vm->def) < 0)
         goto cleanup;
 
-    if (qemuDomainSupportsCheckpointsBlockjobs(vm) < 0)
-        goto cleanup;
-
     if (qemuDomainObjBeginJob(driver, vm, QEMU_JOB_MODIFY) < 0)
         goto cleanup;
 
@@ -18424,12 +18421,6 @@ qemuDomainBlockCommit(virDomainPtr dom,
 
     blockdev = virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_BLOCKDEV);
 
-    if (!blockdev && (flags & VIR_DOMAIN_BLOCK_COMMIT_DELETE)) {
-        virReportError(VIR_ERR_OPERATION_UNSUPPORTED, "%s",
-                       _("deleting committed images is not supported by this VM"));
-        goto endjob;
-    }
-
     /* Convert bandwidth MiB to bytes, if necessary */
     if (!(flags & VIR_DOMAIN_BLOCK_COMMIT_BANDWIDTH_BYTES)) {
         if (speed > LLONG_MAX >> 20) {
@@ -18454,6 +18445,15 @@ qemuDomainBlockCommit(virDomainPtr dom,
     if (qemuDomainDiskBlockJobIsActive(disk))
         goto endjob;
 
+    if (qemuDomainSupportsCheckpointsBlockjobs(vm) < 0)
+        goto endjob;
+
+    if (!blockdev && (flags & VIR_DOMAIN_BLOCK_COMMIT_DELETE)) {
+        virReportError(VIR_ERR_OPERATION_UNSUPPORTED, "%s",
+                       _("deleting committed images is not supported by this VM"));
+        goto endjob;
+    }
+
     if (!top || STREQ(top, disk->dst))
         topSource = disk->src;
     else if (virStorageFileParseChainIndex(disk->dst, top, &topIndex) < 0 ||