qemuDomainBlockPivot: Move check prior to executing the pivot steps

Move the check whether the job is already synchronised to the beginning
of the function so that we don't try to do some of the steps necessary
for pivoting prior to actually wanting to pivot.
Signed-off-by: NPeter Krempa <pkrempa@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>

src/qemu/qemu_driver.c

@@ -17236,6 +17236,13 @@ qemuDomainBlockPivot(virQEMUDriverPtr driver,
     bool blockdev = virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_BLOCKDEV);
     g_autoptr(virJSONValue) actions = NULL;
 
+    if (job->state != QEMU_BLOCKJOB_STATE_READY) {
+        virReportError(VIR_ERR_BLOCK_COPY_ACTIVE,
+                       _("block job '%s' not ready for pivot yet"),
+                       job->name);
+        return -1;
+    }
+
     switch ((qemuBlockJobType) job->type) {
     case QEMU_BLOCKJOB_TYPE_NONE:
     case QEMU_BLOCKJOB_TYPE_LAST:
@@ -17273,13 +17280,6 @@ qemuDomainBlockPivot(virQEMUDriverPtr driver,
         break;
     }
 
-    if (job->state != QEMU_BLOCKJOB_STATE_READY) {
-        virReportError(VIR_ERR_BLOCK_COPY_ACTIVE,
-                       _("block job '%s' not ready for pivot yet"),
-                       job->name);
-        return -1;
-    }
-
     qemuDomainObjEnterMonitor(driver, vm);
     if (blockdev) {
         int rc = 0;