qemu: driver: Move around code to avoid need to rollback

qemuDomainChangeDiskLive rolled back few changes to the disk definition
if changing of the media failed. This can be avoided by moving some code
around.

src/qemu/qemu_driver.c

@@ -7655,8 +7655,6 @@ qemuDomainChangeDiskLive(virConnectPtr conn,
 {
     virDomainDiskDefPtr disk = dev->data.disk;
     virDomainDiskDefPtr orig_disk = NULL;
-    int startupPolicy;
-    int snapshot;
     int ret = -1;
 
     if (virStorageTranslateDiskSourcePool(conn, disk) < 0)
@@ -7674,18 +7672,12 @@ qemuDomainChangeDiskLive(virConnectPtr conn,
         goto cleanup;
     }
 
-    startupPolicy = orig_disk->startupPolicy;
-    snapshot = orig_disk->snapshot;
-
     switch ((virDomainDiskDevice) disk->device) {
     case VIR_DOMAIN_DISK_DEVICE_CDROM:
     case VIR_DOMAIN_DISK_DEVICE_FLOPPY:
         if (!qemuDomainDiskChangeSupported(disk, orig_disk))
             goto cleanup;
 
-        orig_disk->startupPolicy = dev->data.disk->startupPolicy;
-        orig_disk->snapshot = dev->data.disk->snapshot;
-
         if (qemuDomainDiskSourceDiffers(disk, orig_disk)) {
             /* Add the new disk src into shared disk hash table */
             if (qemuAddSharedDevice(driver, dev, vm->def->name) < 0)
@@ -7696,11 +7688,14 @@ qemuDomainChangeDiskLive(virConnectPtr conn,
                                                force) < 0) {
                 ignore_value(qemuRemoveSharedDisk(driver, dev->data.disk,
                                                   vm->def->name));
-                goto rollback;
+                goto cleanup;
             }
 
             dev->data.disk->src = NULL;
         }
+
+        orig_disk->startupPolicy = dev->data.disk->startupPolicy;
+        orig_disk->snapshot = dev->data.disk->snapshot;
         break;
 
     case VIR_DOMAIN_DISK_DEVICE_DISK:
@@ -7719,11 +7714,6 @@ qemuDomainChangeDiskLive(virConnectPtr conn,
     ret = 0;
  cleanup:
     return ret;
-
- rollback:
-    orig_disk->snapshot = snapshot;
-    orig_disk->startupPolicy = startupPolicy;
-    goto cleanup;
 }
 
 static int