tests/qemu-iotests/228

   1 #!/usr/bin/env python3
   2 #
   3 # Test for when a backing file is considered overridden (thus, a
   4 # json:{} filename is generated for the overlay) and when it is not
   5 #
   6 # Copyright (C) 2018 Red Hat, Inc.
   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 # Creator/Owner: Max Reitz <mreitz@redhat.com>
  22
  23 import iotests
  24 from iotests import log, qemu_img, filter_testfiles, filter_imgfmt, \
  25         filter_qmp_testfiles, filter_qmp_imgfmt
  26
  27 # Need backing file and change-backing-file support
  28 iotests.verify_image_format(supported_fmts=['qcow2', 'qed'])
  29 iotests.verify_platform(['linux'])
  30
  31
  32 def log_node_info(node):
  33     log('')
  34
  35     log('bs->filename: ' + node['image']['filename'],
  36         filters=[filter_testfiles, filter_imgfmt])
  37     log('bs->backing_file: ' + node['backing_file'],
  38         filters=[filter_testfiles, filter_imgfmt])
  39
  40     if 'backing-image' in node['image']:
  41         log('bs->backing->bs->filename: ' +
  42             node['image']['backing-image']['filename'],
  43             filters=[filter_testfiles, filter_imgfmt])
  44     else:
  45         log('bs->backing: (none)')
  46
  47     log('')
  48
  49
  50 with iotests.FilePath('base.img') as base_img_path, \
  51      iotests.FilePath('top.img') as top_img_path, \
  52      iotests.VM() as vm:
  53
  54     assert qemu_img('create', '-f', iotests.imgfmt, base_img_path, '64M') == 0
  55     # Choose a funny way to describe the backing filename
  56     assert qemu_img('create', '-f', iotests.imgfmt, '-b',
  57                     'file:' + base_img_path, top_img_path) == 0
  58
  59     vm.launch()
  60
  61     log('--- Implicit backing file ---')
  62     log('')
  63
  64     vm.qmp_log('blockdev-add',
  65                 node_name='node0',
  66                 driver=iotests.imgfmt,
  67                 file={
  68                     'driver': 'file',
  69                     'filename': top_img_path
  70                 },
  71                 filters=[filter_qmp_testfiles, filter_qmp_imgfmt])
  72
  73     # Filename should be plain, and the backing filename should not
  74     # contain the "file:" prefix
  75     log_node_info(vm.node_info('node0'))
  76
  77     vm.qmp_log('blockdev-del', node_name='node0')
  78
  79     log('')
  80     log('--- change-backing-file ---')
  81     log('')
  82
  83     vm.qmp_log('blockdev-add',
  84                node_name='node0',
  85                driver=iotests.imgfmt,
  86                file={
  87                    'driver': 'file',
  88                    'filename': top_img_path
  89                },
  90                filters=[filter_qmp_testfiles, filter_qmp_imgfmt])
  91
  92     # Changing the backing file to a qemu-reported filename should
  93     # result in qemu accepting the corresponding BDS as the implicit
  94     # backing BDS (and thus not generate a json:{} filename).
  95     # So, first, query the backing filename.
  96
  97     backing_filename = \
  98         vm.node_info('node0')['image']['backing-image']['filename']
  99
 100     # Next, change the backing file to something different
 101
 102     vm.qmp_log('change-backing-file',
 103                image_node_name='node0',
 104                device='node0',
 105                backing_file='null-co://',
 106                filters=[filter_qmp_testfiles])
 107
 108     # Now, verify that we get a json:{} filename
 109     # (Image header says "null-co://", actual backing file still is
 110     # base_img_path)
 111
 112     log_node_info(vm.node_info('node0'))
 113
 114     # Change it back
 115     # (To get header and backing file in sync)
 116
 117     vm.qmp_log('change-backing-file',
 118                image_node_name='node0',
 119                device='node0',
 120                backing_file=backing_filename,
 121                filters=[filter_qmp_testfiles])
 122
 123     # And verify that we get our original results
 124
 125     log_node_info(vm.node_info('node0'))
 126
 127     # Finally, try a "file:" prefix.  While this is actually what we
 128     # originally had in the image header, qemu will not reopen the
 129     # backing file here, so it cannot verify that this filename
 130     # "resolves" to the actual backing BDS's filename and will thus
 131     # consider both to be different.
 132     # (This may be fixed in the future.)
 133
 134     vm.qmp_log('change-backing-file',
 135                image_node_name='node0',
 136                device='node0',
 137                backing_file=('file:' + backing_filename),
 138                filters=[filter_qmp_testfiles])
 139
 140     # So now we should get a json:{} filename
 141
 142     log_node_info(vm.node_info('node0'))
 143
 144     # Remove and re-attach so we can see that (as in our first try),
 145     # opening the image anew helps qemu resolve the header backing
 146     # filename.
 147
 148     vm.qmp_log('blockdev-del', node_name='node0')
 149
 150     vm.qmp_log('blockdev-add',
 151                node_name='node0',
 152                driver=iotests.imgfmt,
 153                file={
 154                    'driver': 'file',
 155                    'filename': top_img_path
 156                },
 157                filters=[filter_qmp_testfiles, filter_qmp_imgfmt])
 158
 159     log_node_info(vm.node_info('node0'))
 160
 161     vm.qmp_log('blockdev-del', node_name='node0')
 162
 163     log('')
 164     log('--- Override backing file ---')
 165     log('')
 166
 167     # For this test, we need the plain filename in the image header
 168     # (because qemu cannot "canonicalize"/"resolve" the backing
 169     # filename unless the backing file is opened implicitly with the
 170     # overlay)
 171     assert qemu_img('create', '-f', iotests.imgfmt, '-b', base_img_path,
 172                     top_img_path) == 0
 173
 174     # You can only reliably override backing options by using a node
 175     # reference (or by specifying file.filename, but, well...)
 176     vm.qmp_log('blockdev-add', node_name='null', driver='null-co')
 177
 178     vm.qmp_log('blockdev-add',
 179                node_name='node0',
 180                driver=iotests.imgfmt,
 181                file={
 182                    'driver': 'file',
 183                    'filename': top_img_path
 184                },
 185                backing='null',
 186                filters=[filter_qmp_testfiles, filter_qmp_imgfmt])
 187
 188     # Should get a json:{} filename (and bs->backing_file is
 189     # null-co://, because that field actually has not much to do
 190     # with the header backing filename (except that it is changed by
 191     # change-backing-file))
 192
 193     log_node_info(vm.node_info('node0'))
 194
 195     # Detach the backing file by reopening the whole thing
 196
 197     vm.qmp_log('blockdev-del', node_name='node0')
 198     vm.qmp_log('blockdev-del', node_name='null')
 199
 200     vm.qmp_log('blockdev-add',
 201                node_name='node0',
 202                driver=iotests.imgfmt,
 203                file={
 204                    'driver': 'file',
 205                    'filename': top_img_path
 206                },
 207                backing=None,
 208                filters=[filter_qmp_testfiles, filter_qmp_imgfmt])
 209
 210     # Should get a json:{} filename (because we overrode the backing
 211     # file to not be there)
 212
 213     log_node_info(vm.node_info('node0'))
 214
 215     # Open the original backing file
 216
 217     vm.qmp_log('blockdev-add',
 218                node_name='original-backing',
 219                driver=iotests.imgfmt,
 220                file={
 221                    'driver': 'file',
 222                    'filename': base_img_path
 223                },
 224                filters=[filter_qmp_testfiles, filter_qmp_imgfmt])
 225
 226     # Attach the original backing file to its overlay
 227
 228     vm.qmp_log('blockdev-snapshot',
 229                node='original-backing',
 230                overlay='node0')
 231
 232     # This should give us the original plain result
 233
 234     log_node_info(vm.node_info('node0'))
 235
 236     vm.qmp_log('blockdev-del', node_name='node0')
 237     vm.qmp_log('blockdev-del', node_name='original-backing')
 238
 239     vm.shutdown()