| 1 | #!/usr/bin/env python3 |
| 2 | # group: rw migration |
| 3 | # |
| 4 | # Migrate a VM with a BDS with backing nodes, which runs |
| 5 | # bdrv_invalidate_cache(), which for qcow2 and qed triggers reading the |
| 6 | # backing file string from the image header. Check whether this |
| 7 | # interferes with bdrv_backing_overridden(). |
| 8 | # |
| 9 | # Copyright (C) 2022 Red Hat, Inc. |
| 10 | # |
| 11 | # This program is free software; you can redistribute it and/or modify |
| 12 | # it under the terms of the GNU General Public License as published by |
| 13 | # the Free Software Foundation; either version 2 of the License, or |
| 14 | # (at your option) any later version. |
| 15 | # |
| 16 | # This program is distributed in the hope that it will be useful, |
| 17 | # but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 18 | # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 19 | # GNU General Public License for more details. |
| 20 | # |
| 21 | # You should have received a copy of the GNU General Public License |
| 22 | # along with this program. If not, see <http://www.gnu.org/licenses/>. |
| 23 | # |
| 24 | |
| 25 | import json |
| 26 | import os |
| 27 | from typing import Optional |
| 28 | |
| 29 | import iotests |
| 30 | from iotests import qemu_img_create, qemu_img_info |
| 31 | |
| 32 | |
| 33 | image_size = 1 * 1024 * 1024 |
| 34 | imgs = [os.path.join(iotests.test_dir, f'{i}.img') for i in range(0, 4)] |
| 35 | |
| 36 | mig_sock = os.path.join(iotests.sock_dir, 'mig.sock') |
| 37 | |
| 38 | |
| 39 | class TestPostMigrateFilename(iotests.QMPTestCase): |
| 40 | vm_s: Optional[iotests.VM] = None |
| 41 | vm_d: Optional[iotests.VM] = None |
| 42 | |
| 43 | def setUp(self) -> None: |
| 44 | # Create backing chain of three images, where the backing file strings |
| 45 | # are json:{} filenames |
| 46 | qemu_img_create('-f', iotests.imgfmt, imgs[0], str(image_size)) |
| 47 | for i in range(1, 3): |
| 48 | backing = { |
| 49 | 'driver': iotests.imgfmt, |
| 50 | 'file': { |
| 51 | 'driver': 'file', |
| 52 | 'filename': imgs[i - 1] |
| 53 | } |
| 54 | } |
| 55 | qemu_img_create('-f', iotests.imgfmt, '-F', iotests.imgfmt, |
| 56 | '-b', 'json:' + json.dumps(backing), |
| 57 | imgs[i], str(image_size)) |
| 58 | |
| 59 | def tearDown(self) -> None: |
| 60 | if self.vm_s is not None: |
| 61 | self.vm_s.shutdown() |
| 62 | if self.vm_d is not None: |
| 63 | self.vm_d.shutdown() |
| 64 | |
| 65 | for img in imgs: |
| 66 | try: |
| 67 | os.remove(img) |
| 68 | except OSError: |
| 69 | pass |
| 70 | try: |
| 71 | os.remove(mig_sock) |
| 72 | except OSError: |
| 73 | pass |
| 74 | |
| 75 | def test_migration(self) -> None: |
| 76 | """ |
| 77 | Migrate a VM with the backing chain created in setUp() attached. At |
| 78 | the end of the migration process, the destination will run |
| 79 | bdrv_invalidate_cache(), which for some image formats (qcow2 and qed) |
| 80 | means the backing file string is re-read from the image header. If |
| 81 | this overwrites bs->auto_backing_file, doing so may cause |
| 82 | bdrv_backing_overridden() to become true: The image header reports a |
| 83 | json:{} filename, but when opening it, bdrv_refresh_filename() will |
| 84 | simplify it to a plain simple filename; and when bs->auto_backing_file |
| 85 | and bs->backing->bs->filename differ, bdrv_backing_overridden() becomes |
| 86 | true. |
| 87 | If bdrv_backing_overridden() is true, the BDS will be forced to get a |
| 88 | json:{} filename, which in general is not the end of the world, but not |
| 89 | great. Check whether that happens, i.e. whether migration changes the |
| 90 | node's filename. |
| 91 | """ |
| 92 | |
| 93 | blockdev = { |
| 94 | 'node-name': 'node0', |
| 95 | 'driver': iotests.imgfmt, |
| 96 | 'file': { |
| 97 | 'driver': 'file', |
| 98 | 'filename': imgs[2] |
| 99 | } |
| 100 | } |
| 101 | |
| 102 | self.vm_s = iotests.VM(path_suffix='a') \ |
| 103 | .add_blockdev(json.dumps(blockdev)) |
| 104 | self.vm_d = iotests.VM(path_suffix='b') \ |
| 105 | .add_blockdev(json.dumps(blockdev)) \ |
| 106 | .add_incoming(f'unix:{mig_sock}') |
| 107 | |
| 108 | assert self.vm_s is not None |
| 109 | assert self.vm_d is not None |
| 110 | |
| 111 | self.vm_s.launch() |
| 112 | self.vm_d.launch() |
| 113 | |
| 114 | pre_mig_filename = self.vm_s.node_info('node0')['file'] |
| 115 | |
| 116 | self.vm_s.qmp('migrate', uri=f'unix:{mig_sock}') |
| 117 | |
| 118 | # Wait for migration to be done |
| 119 | self.vm_s.event_wait('STOP') |
| 120 | self.vm_d.event_wait('RESUME') |
| 121 | |
| 122 | post_mig_filename = self.vm_d.node_info('node0')['file'] |
| 123 | |
| 124 | # Verify that the filename hasn't changed from before the migration |
| 125 | self.assertEqual(pre_mig_filename, post_mig_filename) |
| 126 | |
| 127 | self.vm_s.shutdown() |
| 128 | self.vm_s = None |
| 129 | |
| 130 | # For good measure, try creating an overlay and check its backing |
| 131 | # chain below. This is how the issue was originally found. |
| 132 | self.vm_d.cmd('blockdev-snapshot-sync', |
| 133 | format=iotests.imgfmt, |
| 134 | snapshot_file=imgs[3], |
| 135 | node_name='node0', |
| 136 | snapshot_node_name='node0-overlay') |
| 137 | |
| 138 | self.vm_d.shutdown() |
| 139 | self.vm_d = None |
| 140 | |
| 141 | # Check the newly created overlay's backing chain |
| 142 | chain = qemu_img_info('--backing-chain', imgs[3]) |
| 143 | for index, image in enumerate(chain): |
| 144 | self.assertEqual(image['filename'], imgs[3 - index]) |
| 145 | |
| 146 | |
| 147 | if __name__ == '__main__': |
| 148 | # These are the image formats that run their open() function from their |
| 149 | # .bdrv_co_invaliate_cache() implementations, so test them |
| 150 | iotests.main(supported_fmts=['qcow2', 'qed'], |
| 151 | supported_protocols=['file']) |