#!/usr/bin/env python3 # # Copy-on-read tests using a COR filter node # # Copyright (C) 2018 Red Hat, Inc. # # This program is free software; you can redistribute it and/or modify # it under the terms of the GNU General Public License as published by # the Free Software Foundation; either version 2 of the License, or # (at your option) any later version. # # This program is distributed in the hope that it will be useful, # but WITHOUT ANY WARRANTY; without even the implied warranty of # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the # GNU General Public License for more details. # # You should have received a copy of the GNU General Public License # along with this program. If not, see . # # Creator/Owner: Max Reitz import iotests from iotests import log, qemu_img, qemu_io_silent # Need backing file support iotests.verify_image_format(supported_fmts=['qcow2', 'qcow', 'qed', 'vmdk']) iotests.verify_platform(['linux']) log('') log('=== Copy-on-read across nodes ===') log('') # The old copy-on-read mechanism without a filter node cannot request # WRITE_UNCHANGED permissions for its child. Therefore it just tries # to sneak its write by the usual permission system and holds its # fingers crossed. However, that sneaking does not work so well when # there is a filter node in the way: That will receive the write # request and re-issue a new one to its child, which this time is a # proper write request that will make the permission system cough -- # unless there is someone at the top (like a guest device) that has # requested write permissions. # # A COR filter node, however, can request the proper permissions for # its child and therefore is not hit by this issue. with iotests.FilePath('base.img') as base_img_path, \ iotests.FilePath('top.img') as top_img_path, \ iotests.VM() as vm: log('--- Setting up images ---') log('') assert qemu_img('create', '-f', iotests.imgfmt, base_img_path, '64M') == 0 assert qemu_io_silent(base_img_path, '-c', 'write -P 1 0M 1M') == 0 assert qemu_img('create', '-f', iotests.imgfmt, '-b', base_img_path, top_img_path) == 0 assert qemu_io_silent(top_img_path, '-c', 'write -P 2 1M 1M') == 0 log('Done') log('') log('--- Doing COR ---') log('') # Compare with e.g. the following: # vm.add_drive_raw('if=none,node-name=node0,copy-on-read=on,driver=raw,' \ # 'file.driver=%s,file.file.filename=%s' % # (iotests.imgfmt, top_img_path)) # (Remove the blockdev-add instead.) # ((Not tested here because it hits an assertion in the permission # system.)) vm.launch() log(vm.qmp('blockdev-add', node_name='node0', driver='copy-on-read', file={ 'driver': 'raw', 'file': { 'driver': 'copy-on-read', 'file': { 'driver': 'raw', 'file': { 'driver': iotests.imgfmt, 'file': { 'driver': 'file', 'filename': top_img_path }, 'backing': { 'driver': iotests.imgfmt, 'file': { 'driver': 'file', 'filename': base_img_path } } } } } })) # Trigger COR log(vm.qmp('human-monitor-command', command_line='qemu-io node0 "read 0 64M"')) vm.shutdown() log('') log('--- Checking COR result ---') log('') assert qemu_io_silent(base_img_path, '-c', 'discard 0 64M') == 0 assert qemu_io_silent(top_img_path, '-c', 'read -P 1 0M 1M') == 0 assert qemu_io_silent(top_img_path, '-c', 'read -P 2 1M 1M') == 0 log('Done')