xref: /qemu/tests/qemu-iotests/283 (revision 727385c4) 
1#!/usr/bin/env python3
2# group: auto quick
3#
4# Test for copy-before-write filter permission conflict
5#
6# Copyright (c) 2019 Virtuozzo International GmbH.
7#
8# This program is free software; you can redistribute it and/or modify
9# it under the terms of the GNU General Public License as published by
10# the Free Software Foundation; either version 2 of the License, or
11# (at your option) any later version.
12#
13# This program is distributed in the hope that it will be useful,
14# but WITHOUT ANY WARRANTY; without even the implied warranty of
15# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
16# GNU General Public License for more details.
17#
18# You should have received a copy of the GNU General Public License
19# along with this program.  If not, see <http://www.gnu.org/licenses/>.
20#
21
22import iotests
23
24# The test is unrelated to formats, restrict it to qcow2 to avoid extra runs
25iotests.script_initialize(
26    supported_fmts=['qcow2'],
27)
28
29size = 1024 * 1024
30
31""" Test description
32
33When performing a backup, all writes on the source subtree must go through the
34copy-before-write filter so it can copy all data to the target before it is
35changed.  copy-before-write filter is appended above source node, to achieve
36this thing, so all parents of source node are handled. A configuration with
37side parents of source sub-tree with write permission is unsupported (we'd have
38append several copy-before-write filter like nodes to handle such parents). The
39test create an example of such configuration and checks that a backup is then
40not allowed (blockdev-backup command should fail).
41
42The configuration:
43
44    ┌────────┐  target  ┌─────────────┐
45    │ target │ ◀─────── │ backup_top  │
46    └────────┘          └─────────────┘
47                            │
48                            │ backing
49                            ▼
50                        ┌─────────────┐
51                        │   source    │
52                        └─────────────┘
53                            │
54                            │ file
55                            ▼
56                        ┌─────────────┐  write perm   ┌───────┐
57                        │    base     │ ◀──────────── │ other │
58                        └─────────────┘               └───────┘
59
60copy-before-write filter wants to unshare write permission on its source child.
61Write unsharing will be propagated to the "source->base" link and will conflict
62with other node write permission. So permission update will fail and backup job
63will not be started.
64
65Note, that the only thing which prevents backup of running on such
66configuration is default permission propagation scheme. It may be altered by
67different block drivers, so backup will run in invalid configuration. But
68something is better than nothing. Also, before the previous commit (commit
69preceding this test creation), starting backup on such configuration led to
70crash, so current "something" is a lot better, and this test actual goal is
71to check that crash is fixed :)
72"""
73
74vm = iotests.VM()
75vm.launch()
76
77vm.qmp_log('blockdev-add', **{
78    'node-name': 'target',
79    'driver': 'null-co',
80    'size': size,
81})
82
83vm.qmp_log('blockdev-add', **{
84    'node-name': 'source',
85    'driver': 'blkdebug',
86    'image': {'node-name': 'base', 'driver': 'null-co', 'size': size}
87})
88
89vm.qmp_log('blockdev-add', **{
90    'node-name': 'other',
91    'driver': 'blkdebug',
92    'image': 'base',
93    'take-child-perms': ['write']
94})
95
96vm.qmp_log('blockdev-backup', sync='full', device='source', target='target')
97
98vm.shutdown()
99
100
101print('\n=== copy-before-write filter should be gone after job-finalize ===\n')
102
103# Check that the copy-before-write node is gone after job-finalize.
104
105vm = iotests.VM()
106vm.launch()
107
108vm.qmp_log('blockdev-add', **{
109    'node-name': 'source',
110    'driver': 'null-co',
111})
112
113vm.qmp_log('blockdev-add', **{
114    'node-name': 'target',
115    'driver': 'null-co',
116})
117
118vm.qmp_log('blockdev-backup',
119           job_id='backup',
120           device='source',
121           target='target',
122           sync='full',
123           filter_node_name='backup-filter',
124           auto_finalize=False,
125           auto_dismiss=False)
126
127vm.event_wait('BLOCK_JOB_PENDING', 5.0)
128
129# The copy-before-write filter should still be present prior to finalization
130assert vm.node_info('backup-filter') is not None
131
132vm.qmp_log('job-finalize', id='backup')
133vm.event_wait('BLOCK_JOB_COMPLETED', 5.0)
134
135# The filter should be gone now.  Check that by trying to access it
136# with qemu-io (which will most likely crash qemu if it is still
137# there.).
138vm.qmp_log('human-monitor-command',
139           command_line='qemu-io backup-filter "write 0 1M"')
140
141# (Also, do an explicit check.)
142assert vm.node_info('backup-filter') is None
143
144vm.qmp_log('job-dismiss', id='backup')
145vm.event_wait('JOB_STATUS_CHANGE', 5.0, {'data': {'status': 'null'}})
146
147vm.shutdown()
148