openstack
/
nova
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[libvirt] Live migration fails when config_drive_format=iso9660 

This patch enables block live migration with read-only config drive.
Basically it copies config drive to destination host prior to migration
start, so that QEMU will not try to write to read-only device and
therefore it will not raise an exception.

Co-Authored-By: Bartosz Fic <bartosz.fic@intel.com>
Co-Authored-By: Michael Still <mikal@stillhq.com>

Change-Id: I9ddaef658e3d9a77e4982275d7df9e56b0a5459f
Closes-Bug: #1246201
This commit is contained in:
Pawel Koniszewski 2016-07-06 11:04:16 +02:00
parent 3f700b5a5a
commit bc4b9980fa
2 changed files with 48 additions and 31 deletions
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50
nova/tests/unit/virt/libvirt/test_driver.py
View File

@ -84,7 +84,6 @@ from nova.tests import uuidsentinel as uuids
from nova import utils
from nova import version
from nova.virt import block_device as driver_block_device
from nova.virt import configdrive
from nova.virt.disk import api as disk
from nova.virt import driver
from nova.virt import fake
@ -9426,27 +9425,48 @@ class LibvirtConnTestCase(test.NoDBTestCase):
pre_migration_result=True)['pre_live_migration_result'],
target_ret)
def test_pre_live_migration_block_with_config_drive_mocked(self):
# Creating testdata
@mock.patch.object(os, 'mkdir')
@mock.patch('nova.virt.libvirt.utils.get_instance_path_at_destination')
@mock.patch('nova.virt.libvirt.driver.remotefs.'
'RemoteFilesystem.copy_file')
@mock.patch('nova.virt.driver.block_device_info_get_mapping')
@mock.patch('nova.virt.configdrive.required_by', return_value=True)
def test_pre_live_migration_block_with_config_drive_success(
self, mock_required_by, block_device_info_get_mapping,
mock_copy_file, mock_get_instance_path, mock_mkdir):
self.flags(config_drive_format='iso9660')
vol = {'block_device_mapping': [
{'connection_info': 'dummy', 'mount_device': '/dev/sda'},
{'connection_info': 'dummy', 'mount_device': '/dev/sdb'}]}
fake_instance_path = os.path.join(cfg.CONF.instances_path,
'/fake_instance_uuid')
mock_get_instance_path.return_value = fake_instance_path
drvr = libvirt_driver.LibvirtDriver(fake.FakeVirtAPI(), False)
def fake_true(*args, **kwargs):
return True
self.stubs.Set(configdrive, 'required_by', fake_true)
instance = objects.Instance(**self.test_instance)
c = context.get_admin_context()
migrate_data = objects.LibvirtLiveMigrateData()
migrate_data.is_shared_instance_path = False
migrate_data.is_shared_block_storage = False
migrate_data.block_migration = True
migrate_data.instance_relative_path = 'foo'
src = "%s:%s/disk.config" % (instance.host, fake_instance_path)
self.assertRaises(exception.NoLiveMigrationForConfigDriveInLibVirt,
drvr.pre_live_migration, c, instance, vol, None,
None, {'is_shared_instance_path': False,
'is_shared_block_storage': False,
'block_migration': False,
'instance_relative_path': 'foo'})
result = drvr.pre_live_migration(
self.context, instance, vol, [], None, migrate_data)
block_device_info_get_mapping.assert_called_once_with(
{'block_device_mapping': [
{'connection_info': 'dummy', 'mount_device': '/dev/sda'},
{'connection_info': 'dummy', 'mount_device': '/dev/sdb'}
]}
)
mock_copy_file.assert_called_once_with(src, fake_instance_path)
migrate_data.graphics_listen_addrs_vnc = '127.0.0.1'
migrate_data.graphics_listen_addrs_spice = '127.0.0.1'
migrate_data.serial_listen_addr = '127.0.0.1'
self.assertEqual(migrate_data, result)
@mock.patch('nova.virt.driver.block_device_info_get_mapping',
return_value=())

29
nova/virt/libvirt/driver.py
View File

@ -6446,22 +6446,6 @@ class LibvirtDriver(driver.ComputeDriver):
is_shared_instance_path = migrate_data.is_shared_instance_path
is_block_migration = migrate_data.block_migration
if configdrive.required_by(instance):
# NOTE(sileht): configdrive is stored into the block storage
# kvm is a block device, live migration will work
# NOTE(sileht): the configdrive is stored into a shared path
# kvm don't need to migrate it, live migration will work
# NOTE(dims): Using config drive with iso format does not work
# because of a bug in libvirt with read only devices. However
# one can use vfat as config_drive_format which works fine.
# Please see bug/1246201 for details on the libvirt bug.
if (is_shared_block_storage or
is_shared_instance_path or
CONF.config_drive_format == 'vfat'):
pass
else:
raise exception.NoLiveMigrationForConfigDriveInLibVirt()
if not is_shared_instance_path:
instance_dir = libvirt_utils.get_instance_path_at_destination(
instance, migrate_data)
@ -6498,6 +6482,19 @@ class LibvirtDriver(driver.ComputeDriver):
self._create_images_and_backing(
context, instance, instance_dir, disk_info,
fallback_from_host=instance.host)
if (configdrive.required_by(instance) and
CONF.config_drive_format == 'iso9660'):
# NOTE(pkoniszewski): Due to a bug in libvirt iso config
# drive needs to be copied to destination prior to
# migration when instance path is not shared and block
# storage is not shared. Files that are already present
# on destination are excluded from a list of files that
# need to be copied to destination. If we don't do that
# live migration will fail on copying iso config drive to
# destination and writing to read-only device.
# Please see bug/1246201 for more details.
src = "%s:%s/disk.config" % (instance.host, instance_dir)
self._remotefs.copy_file(src, instance_dir)
if not is_block_migration:
# NOTE(angdraug): when block storage is shared between source