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git://sourceware.org/git/lvm2.git
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b4c3382990
When we have two logical volumes which switch their names at the same time we are left with incorrect lookups. Anytime we find an entry by doing a lookup by UUID or by name we will ensure that the lookups are indeed correct. Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1642176
366 lines
11 KiB
Python
366 lines
11 KiB
Python
# Copyright (C) 2015-2016 Red Hat, Inc. All rights reserved.
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#
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# This copyrighted material is made available to anyone wishing to use,
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# modify, copy, or redistribute it subject to the terms and conditions
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# of the GNU General Public License v.2.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program. If not, see <http://www.gnu.org/licenses/>.
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import sys
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import threading
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import traceback
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import dbus
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import os
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import copy
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from . import cfg
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from .utils import log_debug, pv_obj_path_generate, log_error
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from .automatedproperties import AutomatedProperties
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# noinspection PyPep8Naming
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class ObjectManager(AutomatedProperties):
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"""
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Implements the org.freedesktop.DBus.ObjectManager interface
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"""
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def __init__(self, object_path, interface):
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super(ObjectManager, self).__init__(object_path, interface)
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self.set_interface(interface)
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self._ap_o_path = object_path
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self._objects = {}
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self._id_to_object_path = {}
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self.rlock = threading.RLock()
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@staticmethod
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def _get_managed_objects(obj):
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with obj.rlock:
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rc = {}
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try:
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for k, v in list(obj._objects.items()):
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path, props = v[0].emit_data()
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rc[path] = props
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except Exception:
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traceback.print_exc(file=sys.stdout)
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sys.exit(1)
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return rc
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@dbus.service.method(
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dbus_interface="org.freedesktop.DBus.ObjectManager",
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out_signature='a{oa{sa{sv}}}', async_callbacks=('cb', 'cbe'))
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def GetManagedObjects(self, cb, cbe):
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r = cfg.create_request_entry(-1, ObjectManager._get_managed_objects,
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(self, ), cb, cbe, False)
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cfg.worker_q.put(r)
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def locked(self):
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"""
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If some external code need to run across a number of different
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calls into ObjectManager while blocking others they can use this method
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to lock others out.
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:return:
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"""
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return ObjectManagerLock(self.rlock)
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@dbus.service.signal(
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dbus_interface="org.freedesktop.DBus.ObjectManager",
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signature='oa{sa{sv}}')
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def InterfacesAdded(self, object_path, int_name_prop_dict):
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log_debug(
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('SIGNAL: InterfacesAdded(%s, %s)' %
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(str(object_path), str(int_name_prop_dict))))
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@dbus.service.signal(
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dbus_interface="org.freedesktop.DBus.ObjectManager",
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signature='oas')
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def InterfacesRemoved(self, object_path, interface_list):
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log_debug(('SIGNAL: InterfacesRemoved(%s, %s)' %
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(str(object_path), str(interface_list))))
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def validate_lookups(self):
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with self.rlock:
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tmp_lookups = copy.deepcopy(self._id_to_object_path)
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# iterate over all we know, removing from the copy. If all is well
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# we will have zero items left over
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for path, md in self._objects.items():
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obj, lvm_id, uuid = md
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if lvm_id:
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assert path == tmp_lookups[lvm_id]
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del tmp_lookups[lvm_id]
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if uuid:
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assert path == tmp_lookups[uuid]
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del tmp_lookups[uuid]
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rc = len(tmp_lookups)
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if rc:
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# Error condition
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log_error("_id_to_object_path has extraneous lookups!")
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for key, path in tmp_lookups.items():
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log_error("Key= %s, path= %s" % (key, path))
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return rc
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def _lookup_add(self, obj, path, lvm_id, uuid):
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"""
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Store information about what we added to the caches so that we
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can remove it cleanly
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:param obj: The dbus object we are storing
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:param lvm_id: The lvm id for the asset
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:param uuid: The uuid for the asset
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:return:
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"""
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# Note: Only called internally, lock implied
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# We could have a temp entry from the forward creation of a path
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self._lookup_remove(path)
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self._objects[path] = (obj, lvm_id, uuid)
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# Make sure we have one or the other
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assert lvm_id or uuid
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if lvm_id:
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self._id_to_object_path[lvm_id] = path
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if uuid:
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self._id_to_object_path[uuid] = path
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def _lookup_remove(self, obj_path):
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# Note: Only called internally, lock implied
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if obj_path in self._objects:
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(obj, lvm_id, uuid) = self._objects[obj_path]
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if lvm_id in self._id_to_object_path:
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del self._id_to_object_path[lvm_id]
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if uuid in self._id_to_object_path:
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del self._id_to_object_path[uuid]
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del self._objects[obj_path]
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def lookup_update(self, dbus_obj, new_uuid, new_lvm_id):
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with self.rlock:
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obj_path = dbus_obj.dbus_object_path()
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self._lookup_remove(obj_path)
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self._lookup_add(
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dbus_obj, obj_path,
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new_lvm_id, new_uuid)
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def object_paths_by_type(self, o_type):
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with self.rlock:
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rc = {}
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for k, v in list(self._objects.items()):
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if isinstance(v[0], o_type):
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rc[k] = True
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return rc
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def register_object(self, dbus_object, emit_signal=False):
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"""
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Given a dbus object add it to the collection
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:param dbus_object: Dbus object to register
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:param emit_signal: If true emit a signal for interfaces added
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"""
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with self.rlock:
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path, props = dbus_object.emit_data()
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# print('Registering object path %s for %s' %
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# (path, dbus_object.lvm_id))
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# We want fast access to the object by a number of different ways
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# so we use multiple hashs with different keys
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self._lookup_add(dbus_object, path, dbus_object.lvm_id,
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dbus_object.Uuid)
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if emit_signal:
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self.InterfacesAdded(path, props)
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def remove_object(self, dbus_object, emit_signal=False):
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"""
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Given a dbus object, remove it from the collection and remove it
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from the dbus framework as well
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:param dbus_object: Dbus object to remove
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:param emit_signal: If true emit the interfaces removed signal
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"""
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with self.rlock:
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# Store off the object path and the interface first
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path = dbus_object.dbus_object_path()
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interfaces = dbus_object.interface()
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# print('UN-Registering object path %s for %s' %
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# (path, dbus_object.lvm_id))
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self._lookup_remove(path)
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# Remove from dbus library
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dbus_object.remove_from_connection(cfg.bus, path)
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# Optionally emit a signal
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if emit_signal:
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self.InterfacesRemoved(path, interfaces)
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def get_object_by_path(self, path):
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"""
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Given a dbus path return the object registered for it
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:param path: The dbus path
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:return: The object
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"""
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with self.rlock:
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if path in self._objects:
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return self._objects[path][0]
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return None
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def get_object_by_uuid_lvm_id(self, uuid, lvm_id):
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with self.rlock:
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return self.get_object_by_path(
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self.get_object_path_by_uuid_lvm_id(uuid, lvm_id))
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def get_object_by_lvm_id(self, lvm_id):
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"""
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Given an lvm identifier, return the object registered for it
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:param lvm_id: The lvm identifier
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"""
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with self.rlock:
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lookup_rc = self._id_lookup(lvm_id)
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if lookup_rc:
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return self.get_object_by_path(lookup_rc)
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return None
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def get_object_path_by_lvm_id(self, lvm_id):
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"""
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Given an lvm identifier, return the object path for it
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:param lvm_id: The lvm identifier
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:return: Object path or '/' if not found
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"""
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with self.rlock:
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lookup_rc = self._id_lookup(lvm_id)
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if lookup_rc:
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return lookup_rc
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return '/'
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def _id_verify(self, path, uuid, lvm_id):
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"""
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Ensure our lookups are correct
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NOTE: Internal call, assumes under object manager lock
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:param path: Path to object we looked up
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:param uuid: uuid lookup
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:param lvm_id: lvm_id lookup
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:return: None
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"""
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# There is no durable non-changeable name in lvm
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if lvm_id != uuid:
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obj = self.get_object_by_path(path)
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self._lookup_add(obj, path, lvm_id, uuid)
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def _id_lookup(self, the_id):
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path = None
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if the_id:
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# The _id_to_object_path contains hash keys for everything, so
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# uuid and lvm_id
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if the_id in self._id_to_object_path:
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path = self._id_to_object_path[the_id]
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else:
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if "/" in the_id:
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if the_id.startswith('/'):
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# We could have a pv device path lookup that failed,
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# lets try canonical form and try again.
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canonical = os.path.realpath(the_id)
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if canonical in self._id_to_object_path:
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path = self._id_to_object_path[canonical]
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else:
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vg, lv = the_id.split("/", 1)
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int_lvm_id = vg + "/" + ("[%s]" % lv)
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if int_lvm_id in self._id_to_object_path:
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path = self._id_to_object_path[int_lvm_id]
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return path
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def get_object_path_by_uuid_lvm_id(self, uuid, lvm_id, path_create=None):
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"""
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For a given lvm asset return the dbus object path registered for it.
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This method first looks up by uuid and then by lvm_id. You
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can search by just one by setting uuid == lvm_id (uuid or lvm_id).
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If the object is not found and path_create is a not None, the
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path_create function will be called to create a new object path and
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register it with the object manager for the specified uuid & lvm_id.
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Note: If path create is not None, uuid and lvm_id cannot be equal
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:param uuid: The uuid for the lvm object we are searching for
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:param lvm_id: The lvm name (eg. pv device path, vg name, lv full name)
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:param path_create: If not None, create the path using this function if
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we fail to find the object by uuid or lvm_id.
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:returns None if lvm asset not found and path_create == None otherwise
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a valid dbus object path
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"""
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with self.rlock:
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assert lvm_id
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assert uuid
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if path_create:
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assert uuid != lvm_id
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# Check for Manager.LookUpByLvmId query, we cannot
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# check/verify/update the uuid and lvm_id lookups so don't!
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if uuid == lvm_id:
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path = self._id_lookup(lvm_id)
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else:
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# We have a uuid and a lvm_id we can do sanity checks to ensure
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# that they are consistent
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# If a PV is missing it's device path is '[unknown]' or some
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# other text derivation of unknown. When we find that a PV is
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# missing we will clear out the lvm_id as it's likely not unique
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# and thus not useful and potentially harmful for lookups.
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if path_create == pv_obj_path_generate and \
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cfg.db.pv_missing(uuid):
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lvm_id = None
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# Lets check for the uuid first
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path = self._id_lookup(uuid)
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if path:
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# Ensure table lookups are correct
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self._id_verify(path, uuid, lvm_id)
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else:
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# Unable to find by UUID, lets lookup by lvm_id
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path = self._id_lookup(lvm_id)
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if path:
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# Ensure table lookups are correct
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self._id_verify(path, uuid, lvm_id)
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else:
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# We have exhausted all lookups, let's create if we can
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if path_create:
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path = path_create()
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self._lookup_add(None, path, lvm_id, uuid)
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# print('get_object_path_by_lvm_id(%s, %s, %s): return %s' %
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# (uuid, lvm_id, str(path_create), path))
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return path
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class ObjectManagerLock(object):
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"""
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The sole purpose of this class is to allow other code the ability to
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lock the object manager using a `with` statement, eg.
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with cfg.om.locked():
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# Do stuff with object manager
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This will ensure that the lock is always released (assuming this is done
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correctly)
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"""
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def __init__(self, recursive_lock):
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self._lock = recursive_lock
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def __enter__(self):
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# Acquire lock
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self._lock.acquire()
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# noinspection PyUnusedLocal
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def __exit__(self, e_type, e_value, e_traceback):
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# Release lock
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self._lock.release()
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self._lock = None
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