installer: Flush all disk buffers after the installation has finished.

src/installer/hw.c

@@ -969,3 +969,9 @@ int hw_write_fstab(struct hw_destination* dest) {
 
 	return 0;
 }
+
+void hw_sync() {
+	sync();
+	sync();
+	sync();
+}

src/installer/hw.h

@@ -124,4 +124,6 @@ int hw_stop_all_raid_arrays();
 int hw_install_bootloader(struct hw_destination* dest);
 int hw_write_fstab(struct hw_destination* dest);
 
+void hw_sync();
+
 #endif /* HEADER_HW_H */

src/installer/main.c

@@ -676,6 +676,8 @@ EXIT:
 	free(sourcedrive);
 
 	if (destination) {
+		hw_sync();
+
 		hw_umount_filesystems(destination, DESTINATION_MOUNT_PATH);
 		free(destination);
 	}