File virtinst-set-cache-mode-unsafe-for-install.patch of Package virt-manager

Set cache mode for target installation disk to unsafe for better
performance.
Index: virt-manager-3.3.0/virtinst/install/installer.py
===================================================================
--- virt-manager-3.3.0.orig/virtinst/install/installer.py
+++ virt-manager-3.3.0/virtinst/install/installer.py
@@ -567,16 +567,29 @@ class Installer(object):
 
     def _build_postboot_xml(self, final_xml, meter):
         initial_guest = Guest(self.conn, parsexml=final_xml)
+        # At install time set the target disk to 'unsafe' for
+        # better performance if the target is not a block device
+        saved_cache = "None"
+        if initial_guest.devices.disk:
+            target_disk = initial_guest.devices.disk[0]
+            saved_cache = target_disk.driver_cache
+            if target_disk.type != DeviceDisk.TYPE_BLOCK and target_disk.driver_io != "native":
+                target_disk.driver_cache = DeviceDisk.CACHE_MODE_UNSAFE
+
         self._alter_bootconfig(initial_guest)
         self._alter_install_resources(initial_guest, meter)
         if self.has_cloudinit():
             initial_guest.set_smbios_serial_cloudinit()
 
+        install_xml = initial_guest.get_xml()
+        if saved_cache != "None":
+            target_disk.driver_cache = saved_cache
+
         final_guest = Guest(self.conn, parsexml=final_xml)
         self._remove_install_cdrom_media(final_guest)
         self._remove_unattended_install_cdrom_device(final_guest)
 
-        return initial_guest.get_xml(), final_guest.get_xml()
+        return install_xml, final_guest.get_xml()
 
     def _build_xml(self, guest, meter):
         initial_xml = None