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# Copyright 2018 Red Hat, Inc.
# All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.
import contextlib
import os
from typing import Generator
from oslo_concurrency import lockutils
from oslo_concurrency import processutils as putils
def check_manual_scan() -> bool:
if os.name == 'nt':
return False
try:
putils.execute('grep', '-F', 'node.session.scan', '/sbin/iscsiadm')
except putils.ProcessExecutionError:
return False
return True
ISCSI_SUPPORTS_MANUAL_SCAN = check_manual_scan()
@contextlib.contextmanager
def guard_connection(device: dict) -> Generator:
"""Context Manager handling locks for attach/detach operations.
In Cinder microversion 3.69 the shared_targets field for volumes are
tristate:
- True ==> Lock if iSCSI initiator doesn't support manual scans
- False ==> Never lock.
- None ==> Always lock.
"""
shared = device.get('shared_targets', False)
if (shared is not None and ISCSI_SUPPORTS_MANUAL_SCAN) or shared is False:
yield
else:
# Cinder passes an OVO, but Nova passes a dictionary, so we use dict
# key access that works with both.
with lockutils.lock(device['service_uuid'], 'os-brick-',
external=True):
yield
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