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.script_initialize(
  29     supported_fmts=['qcow2', 'qed'],
  30     supported_platforms=['linux'],
  31 )
  32
  33
  34 def log_node_info(node):
  35     log('')
  36
  37     log('bs->filename: ' + node['image']['filename'],
  38         filters=[filter_testfiles, filter_imgfmt])
  39     log('bs->backing_file: ' + node['backing_file'],
  40         filters=[filter_testfiles, filter_imgfmt])
  41
  42     if 'backing-image' in node['image']:
  43         log('bs->backing->bs->filename: ' +
  44             node['image']['backing-image']['filename'],
  45             filters=[filter_testfiles, filter_imgfmt])
  46     else:
  47         log('bs->backing: (none)')
  48
  49     log('')
  50
  51
  52 with iotests.FilePath('base.img') as base_img_path, \
  53      iotests.FilePath('top.img') as top_img_path, \
  54      iotests.VM() as vm:
  55
  56     assert qemu_img('create', '-f', iotests.imgfmt, base_img_path, '64M') == 0
  57     # Choose a funny way to describe the backing filename
  58     assert qemu_img('create', '-f', iotests.imgfmt, '-b',
  59                     'file:' + base_img_path, '-F', iotests.imgfmt,
  60                     top_img_path) == 0
  61
  62     vm.launch()
  63
  64     log('--- Implicit backing file ---')
  65     log('')
  66
  67     vm.qmp_log('blockdev-add',
  68                 node_name='node0',
  69                 driver=iotests.imgfmt,
  70                 file={
  71                     'driver': 'file',
  72                     'filename': top_img_path
  73                 },
  74                 filters=[filter_qmp_testfiles, filter_qmp_imgfmt])
  75
  76     # Filename should be plain, and the backing filename should not
  77     # contain the "file:" prefix
  78     log_node_info(vm.node_info('node0'))
  79
  80     vm.qmp_log('blockdev-del', node_name='node0')
  81
  82     log('')
  83     log('--- change-backing-file ---')
  84     log('')
  85
  86     vm.qmp_log('blockdev-add',
  87                node_name='node0',
  88                driver=iotests.imgfmt,
  89                file={
  90                    'driver': 'file',
  91                    'filename': top_img_path
  92                },
  93                filters=[filter_qmp_testfiles, filter_qmp_imgfmt])
  94
  95     # Changing the backing file to a qemu-reported filename should
  96     # result in qemu accepting the corresponding BDS as the implicit
  97     # backing BDS (and thus not generate a json:{} filename).
  98     # So, first, query the backing filename.
  99
 100     backing_filename = \
 101         vm.node_info('node0')['image']['backing-image']['filename']
 102
 103     # Next, change the backing file to something different
 104
 105     vm.qmp_log('change-backing-file',
 106                image_node_name='node0',
 107                device='node0',
 108                backing_file='null-co://',
 109                filters=[filter_qmp_testfiles])
 110
 111     # Now, verify that we get a json:{} filename
 112     # (Image header says "null-co://", actual backing file still is
 113     # base_img_path)
 114
 115     log_node_info(vm.node_info('node0'))
 116
 117     # Change it back
 118     # (To get header and backing file in sync)
 119
 120     vm.qmp_log('change-backing-file',
 121                image_node_name='node0',
 122                device='node0',
 123                backing_file=backing_filename,
 124                filters=[filter_qmp_testfiles])
 125
 126     # And verify that we get our original results
 127
 128     log_node_info(vm.node_info('node0'))
 129
 130     # Finally, try a "file:" prefix.  While this is actually what we
 131     # originally had in the image header, qemu will not reopen the
 132     # backing file here, so it cannot verify that this filename
 133     # "resolves" to the actual backing BDS's filename and will thus
 134     # consider both to be different.
 135     # (This may be fixed in the future.)
 136
 137     vm.qmp_log('change-backing-file',
 138                image_node_name='node0',
 139                device='node0',
 140                backing_file=('file:' + backing_filename),
 141                filters=[filter_qmp_testfiles])
 142
 143     # So now we should get a json:{} filename
 144
 145     log_node_info(vm.node_info('node0'))
 146
 147     # Remove and re-attach so we can see that (as in our first try),
 148     # opening the image anew helps qemu resolve the header backing
 149     # filename.
 150
 151     vm.qmp_log('blockdev-del', node_name='node0')
 152
 153     vm.qmp_log('blockdev-add',
 154                node_name='node0',
 155                driver=iotests.imgfmt,
 156                file={
 157                    'driver': 'file',
 158                    'filename': top_img_path
 159                },
 160                filters=[filter_qmp_testfiles, filter_qmp_imgfmt])
 161
 162     log_node_info(vm.node_info('node0'))
 163
 164     vm.qmp_log('blockdev-del', node_name='node0')
 165
 166     log('')
 167     log('--- Override backing file ---')
 168     log('')
 169
 170     # For this test, we need the plain filename in the image header
 171     # (because qemu cannot "canonicalize"/"resolve" the backing
 172     # filename unless the backing file is opened implicitly with the
 173     # overlay)
 174     assert qemu_img('create', '-f', iotests.imgfmt, '-b', base_img_path,
 175                     '-F', iotests.imgfmt, top_img_path) == 0
 176
 177     # You can only reliably override backing options by using a node
 178     # reference (or by specifying file.filename, but, well...)
 179     vm.qmp_log('blockdev-add', node_name='null', driver='null-co')
 180
 181     vm.qmp_log('blockdev-add',
 182                node_name='node0',
 183                driver=iotests.imgfmt,
 184                file={
 185                    'driver': 'file',
 186                    'filename': top_img_path
 187                },
 188                backing='null',
 189                filters=[filter_qmp_testfiles, filter_qmp_imgfmt])
 190
 191     # Should get a json:{} filename (and bs->backing_file is
 192     # null-co://, because that field actually has not much to do
 193     # with the header backing filename (except that it is changed by
 194     # change-backing-file))
 195
 196     log_node_info(vm.node_info('node0'))
 197
 198     # Detach the backing file by reopening the whole thing
 199
 200     vm.qmp_log('blockdev-del', node_name='node0')
 201     vm.qmp_log('blockdev-del', node_name='null')
 202
 203     vm.qmp_log('blockdev-add',
 204                node_name='node0',
 205                driver=iotests.imgfmt,
 206                file={
 207                    'driver': 'file',
 208                    'filename': top_img_path
 209                },
 210                backing=None,
 211                filters=[filter_qmp_testfiles, filter_qmp_imgfmt])
 212
 213     # Should get a json:{} filename (because we overrode the backing
 214     # file to not be there)
 215
 216     log_node_info(vm.node_info('node0'))
 217
 218     # Open the original backing file
 219
 220     vm.qmp_log('blockdev-add',
 221                node_name='original-backing',
 222                driver=iotests.imgfmt,
 223                file={
 224                    'driver': 'file',
 225                    'filename': base_img_path
 226                },
 227                filters=[filter_qmp_testfiles, filter_qmp_imgfmt])
 228
 229     # Attach the original backing file to its overlay
 230
 231     vm.qmp_log('blockdev-snapshot',
 232                node='original-backing',
 233                overlay='node0')
 234
 235     # This should give us the original plain result
 236
 237     log_node_info(vm.node_info('node0'))
 238
 239     vm.qmp_log('blockdev-del', node_name='node0')
 240     vm.qmp_log('blockdev-del', node_name='original-backing')
 241
 242     vm.shutdown()