tests/qemu-iotests/216

   1 #!/usr/bin/env python3
   2 # group: rw quick
   3 #
   4 # Copy-on-read tests using a COR filter node
   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: Hanna Reitz <hreitz@redhat.com>
  22
  23 import iotests
  24 from iotests import log, qemu_img, qemu_io
  25
  26 # Need backing file support
  27 iotests.script_initialize(supported_fmts=['qcow2', 'qcow', 'qed', 'vmdk'],
  28                           supported_platforms=['linux'])
  29
  30 log('')
  31 log('=== Copy-on-read across nodes ===')
  32 log('')
  33
  34 # The old copy-on-read mechanism without a filter node cannot request
  35 # WRITE_UNCHANGED permissions for its child.  Therefore it just tries
  36 # to sneak its write by the usual permission system and holds its
  37 # fingers crossed.  However, that sneaking does not work so well when
  38 # there is a filter node in the way: That will receive the write
  39 # request and re-issue a new one to its child, which this time is a
  40 # proper write request that will make the permission system cough --
  41 # unless there is someone at the top (like a guest device) that has
  42 # requested write permissions.
  43 #
  44 # A COR filter node, however, can request the proper permissions for
  45 # its child and therefore is not hit by this issue.
  46
  47 with iotests.FilePath('base.img') as base_img_path, \
  48      iotests.FilePath('top.img') as top_img_path, \
  49      iotests.VM() as vm:
  50
  51     log('--- Setting up images ---')
  52     log('')
  53
  54     qemu_img('create', '-f', iotests.imgfmt, base_img_path, '64M')
  55     qemu_io(base_img_path, '-c', 'write -P 1 0M 1M')
  56     qemu_img('create', '-f', iotests.imgfmt, '-b', base_img_path,
  57              '-F', iotests.imgfmt, top_img_path)
  58     qemu_io(top_img_path,  '-c', 'write -P 2 1M 1M')
  59
  60     log('Done')
  61
  62     log('')
  63     log('--- Doing COR ---')
  64     log('')
  65
  66     # Compare with e.g. the following:
  67     #   vm.add_drive_raw('if=none,node-name=node0,copy-on-read=on,driver=raw,' \
  68     #                    'file.driver=%s,file.file.filename=%s' %
  69     #                       (iotests.imgfmt, top_img_path))
  70     # (Remove the blockdev-add instead.)
  71     # ((Not tested here because it hits an assertion in the permission
  72     #   system.))
  73
  74     vm.launch()
  75
  76     log(vm.qmp('blockdev-add',
  77                     node_name='node0',
  78                     driver='copy-on-read',
  79                     file={
  80                         'driver': 'raw',
  81                         'file': {
  82                             'driver': 'copy-on-read',
  83                             'file': {
  84                                 'driver': 'raw',
  85                                 'file': {
  86                                     'driver': iotests.imgfmt,
  87                                     'file': {
  88                                         'driver': 'file',
  89                                         'filename': top_img_path
  90                                     },
  91                                     'backing': {
  92                                         'driver': iotests.imgfmt,
  93                                         'file': {
  94                                             'driver': 'file',
  95                                             'filename': base_img_path
  96                                         }
  97                                     }
  98                                 }
  99                             }
 100                         }
 101                     }))
 102
 103     # Trigger COR
 104     log(vm.qmp('human-monitor-command',
 105                command_line='qemu-io node0 "read 0 64M"'))
 106
 107     vm.shutdown()
 108
 109     log('')
 110     log('--- Checking COR result ---')
 111     log('')
 112
 113     qemu_io(base_img_path, '-c', 'discard 0 64M')
 114     qemu_io(top_img_path,  '-c', 'read -P 1 0M 1M')
 115     qemu_io(top_img_path,  '-c', 'read -P 2 1M 1M')
 116
 117     log('Done')