qemu/tests/qemu-iotests/tests/backup-discard-source

#!/usr/bin/env python3
#
# Test backup discard-source parameter
#
# Copyright (c) Virtuozzo International GmbH.
# Copyright (c) Yandex
#
# 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 <http://www.gnu.org/licenses/>.
#

import os

import iotests
from iotests import qemu_img_create, qemu_img_map, qemu_io


temp_img = os.path.join(iotests.test_dir, 'temp')
source_img = os.path.join(iotests.test_dir, 'source')
target_img = os.path.join(iotests.test_dir, 'target')
size = 1024 * 1024


class TestBackup(iotests.QMPTestCase):
    def setUp(self):
        qemu_img_create('-f', iotests.imgfmt, source_img, str(size))
        qemu_img_create('-f', iotests.imgfmt, temp_img, str(size))
        qemu_img_create('-f', iotests.imgfmt, target_img, str(size))
        qemu_io('-c', 'write 0 1M', source_img)

        self.vm = iotests.VM()
        self.vm.launch()

        self.vm.cmd('blockdev-add', {
            'node-name': 'cbw',
            'driver': 'copy-before-write',
            'file': {
                'driver': iotests.imgfmt,
                'file': {
                    'driver': 'file',
                    'filename': source_img,
                }
            },
            'target': {
                'driver': iotests.imgfmt,
                'discard': 'unmap',
                'node-name': 'temp',
                'file': {
                    'driver': 'file',
                    'filename': temp_img
                }
            }
        })

        self.vm.cmd('blockdev-add', {
            'node-name': 'access',
            'discard': 'unmap',
            'driver': 'snapshot-access',
            'file': 'cbw'
        })

        self.vm.cmd('blockdev-add', {
            'driver': iotests.imgfmt,
            'node-name': 'target',
            'file': {
                'driver': 'file',
                'filename': target_img
            }
        })

        self.bitmap = {
            'node': 'temp',
            'name': 'bitmap0'
        }

        self.vm.cmd('block-dirty-bitmap-add', self.bitmap)

    def tearDown(self):
        # That should fail, because region is discarded
        self.vm.hmp_qemu_io('access', 'read 0 1M')

        self.vm.shutdown()

        self.assertTrue('read failed: Permission denied' in self.vm.get_log())

        # Final check that temp image is empty
        mapping = qemu_img_map(temp_img)
        self.assertEqual(len(mapping), 1)
        self.assertEqual(mapping[0]['start'], 0)
        self.assertEqual(mapping[0]['length'], size)
        self.assertEqual(mapping[0]['data'], False)

        os.remove(temp_img)
        os.remove(source_img)
        os.remove(target_img)

    def do_backup(self):
        self.vm.cmd('blockdev-backup', device='access',
                    sync='full', target='target',
                    job_id='backup0',
                    discard_source=True)

        self.vm.event_wait(name='BLOCK_JOB_COMPLETED')

    def get_bitmap_count(self):
        nodes = self.vm.cmd('query-named-block-nodes', flat=True)
        temp = next(n for n in nodes if n['node-name'] == 'temp')
        bitmap = temp['dirty-bitmaps'][0]
        assert bitmap['name'] == self.bitmap['name']
        return bitmap['count']

    def test_discard_written(self):
        """
        1. Guest writes
        2. copy-before-write operation, data is stored to temp
        3. start backup(discard_source=True), check that data is
           removed from temp
        """
        # Trigger copy-before-write operation
        result = self.vm.hmp_qemu_io('cbw', 'write 0 1M')
        self.assert_qmp(result, 'return', '')

        # Check that data is written to temporary image
        self.assertEqual(self.get_bitmap_count(), size)

        self.do_backup()

    def test_discard_cbw(self):
        """
        1. do backup(discard_source=True), which should inform
           copy-before-write that data is not needed anymore
        2. Guest writes
        3. Check that copy-before-write operation is not done
        """
        self.do_backup()

        # backup job did discard operation and pollute the bitmap,
        # we have to clean the bitmap, to check next write
        self.assertEqual(self.get_bitmap_count(), size)
        self.vm.cmd('block-dirty-bitmap-clear', self.bitmap)

        # Try trigger copy-before-write operation
        result = self.vm.hmp_qemu_io('cbw', 'write 0 1M')
        self.assert_qmp(result, 'return', '')

        # Check that data is not written to temporary image, as region
        # is discarded from copy-before-write process
        self.assertEqual(self.get_bitmap_count(), 0)


if __name__ == '__main__':
    iotests.main(supported_fmts=['qcow2'],
                 supported_protocols=['file'])