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lvm2/daemons/lvmdbusd/objectmanager.py
Tony Asleson 063265eacd lvmdbusd: Allow PV device names to be '[unknown]'
When a PV device is missing lvm will return '[unknown]' for the device
path.  The object manager keeps a hash table lookup for uuid and for PV's
device name.  When we had multiple PVs with the same device path we
we only had 1 key in the table for the lvm id (device path).  This caused
a problem when the PV device transitioned from '[unknown]' to known as any
subsequent transitions would cause an exception:

Traceback (most recent call last):
  File "/usr/lib/python3.5/site-packages/lvmdbusd/request.py", line 66, in run_cmd
    result = self.method(*self.arguments)
  File "/usr/lib/python3.5/site-packages/lvmdbusd/manager.py", line 205, in _pv_scan
    cfg.load()
  File "/usr/lib/python3.5/site-packages/lvmdbusd/fetch.py", line 24, in load
    cache_refresh=False)[1]
  File "/usr/lib/python3.5/site-packages/lvmdbusd/pv.py", line 48, in load_pvs
    emit_signal, cache_refresh)
  File "/usr/lib/python3.5/site-packages/lvmdbusd/loader.py", line 80, in common
    cfg.om.remove_object(cfg.om.get_object_by_path(k), True)
  File "/usr/lib/python3.5/site-packages/lvmdbusd/objectmanager.py", line 153, in remove_object
    self._lookup_remove(path)
  File "/usr/lib/python3.5/site-packages/lvmdbusd/objectmanager.py", line 97, in _lookup_remove
    del self._id_to_object_path[lvm_id]
KeyError: '[unknown]'

when trying to delete a key that wasn't present.  In this case we don't add a
lookup key for the device path and the PV can only be located by UUID.

Ref: https://bugzilla.redhat.com/show_bug.cgi?id=1379357
2016-09-27 13:28:54 -05:00

346 lines
10 KiB
Python

# Copyright (C) 2015-2016 Red Hat, Inc. All rights reserved.
#
# This copyrighted material is made available to anyone wishing to use,
# modify, copy, or redistribute it subject to the terms and conditions
# of the GNU General Public License v.2.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
import sys
import threading
import traceback
import dbus
import os
from . import cfg
from .utils import log_debug, pv_obj_path_generate
from .automatedproperties import AutomatedProperties
# noinspection PyPep8Naming
class ObjectManager(AutomatedProperties):
"""
Implements the org.freedesktop.DBus.ObjectManager interface
"""
def __init__(self, object_path, interface):
super(ObjectManager, self).__init__(object_path, interface)
self.set_interface(interface)
self._ap_o_path = object_path
self._objects = {}
self._id_to_object_path = {}
self.rlock = threading.RLock()
@dbus.service.method(
dbus_interface="org.freedesktop.DBus.ObjectManager",
out_signature='a{oa{sa{sv}}}')
def GetManagedObjects(self):
with self.rlock:
rc = {}
try:
for k, v in list(self._objects.items()):
path, props = v[0].emit_data()
rc[path] = props
except Exception:
traceback.print_exc(file=sys.stdout)
sys.exit(1)
return rc
def locked(self):
"""
If some external code need to run across a number of different
calls into ObjectManager while blocking others they can use this method
to lock others out.
:return:
"""
return ObjectManagerLock(self.rlock)
@dbus.service.signal(
dbus_interface="org.freedesktop.DBus.ObjectManager",
signature='oa{sa{sv}}')
def InterfacesAdded(self, object_path, int_name_prop_dict):
log_debug(
('SIGNAL: InterfacesAdded(%s, %s)' %
(str(object_path), str(int_name_prop_dict))))
@dbus.service.signal(
dbus_interface="org.freedesktop.DBus.ObjectManager",
signature='oas')
def InterfacesRemoved(self, object_path, interface_list):
log_debug(('SIGNAL: InterfacesRemoved(%s, %s)' %
(str(object_path), str(interface_list))))
def _lookup_add(self, obj, path, lvm_id, uuid):
"""
Store information about what we added to the caches so that we
can remove it cleanly
:param obj: The dbus object we are storing
:param lvm_id: The lvm id for the asset
:param uuid: The uuid for the asset
:return:
"""
# Note: Only called internally, lock implied
# We could have a temp entry from the forward creation of a path
self._lookup_remove(path)
self._objects[path] = (obj, lvm_id, uuid)
# Make sure we have one or the other
assert lvm_id or uuid
if lvm_id:
self._id_to_object_path[lvm_id] = path
if uuid:
self._id_to_object_path[uuid] = path
def _lookup_remove(self, obj_path):
# Note: Only called internally, lock implied
if obj_path in self._objects:
(obj, lvm_id, uuid) = self._objects[obj_path]
if lvm_id in self._id_to_object_path:
del self._id_to_object_path[lvm_id]
if uuid in self._id_to_object_path:
del self._id_to_object_path[uuid]
del self._objects[obj_path]
def lookup_update(self, dbus_obj, new_uuid, new_lvm_id):
with self.rlock:
obj_path = dbus_obj.dbus_object_path()
self._lookup_remove(obj_path)
self._lookup_add(
dbus_obj, obj_path,
new_lvm_id, new_uuid)
def object_paths_by_type(self, o_type):
with self.rlock:
rc = {}
for k, v in list(self._objects.items()):
if isinstance(v[0], o_type):
rc[k] = True
return rc
def register_object(self, dbus_object, emit_signal=False):
"""
Given a dbus object add it to the collection
:param dbus_object: Dbus object to register
:param emit_signal: If true emit a signal for interfaces added
"""
with self.rlock:
path, props = dbus_object.emit_data()
# print('Registering object path %s for %s' %
# (path, dbus_object.lvm_id))
# We want fast access to the object by a number of different ways
# so we use multiple hashs with different keys
self._lookup_add(dbus_object, path, dbus_object.lvm_id,
dbus_object.Uuid)
if emit_signal:
self.InterfacesAdded(path, props)
def remove_object(self, dbus_object, emit_signal=False):
"""
Given a dbus object, remove it from the collection and remove it
from the dbus framework as well
:param dbus_object: Dbus object to remove
:param emit_signal: If true emit the interfaces removed signal
"""
with self.rlock:
# Store off the object path and the interface first
path = dbus_object.dbus_object_path()
interfaces = dbus_object.interface()
# print 'UN-Registering object path %s for %s' % \
# (path, dbus_object.lvm_id)
self._lookup_remove(path)
# Remove from dbus library
dbus_object.remove_from_connection(cfg.bus, path)
# Optionally emit a signal
if emit_signal:
self.InterfacesRemoved(path, interfaces)
def get_object_by_path(self, path):
"""
Given a dbus path return the object registered for it
:param path: The dbus path
:return: The object
"""
with self.rlock:
if path in self._objects:
return self._objects[path][0]
return None
def get_object_by_uuid_lvm_id(self, uuid, lvm_id):
with self.rlock:
return self.get_object_by_path(
self.get_object_path_by_uuid_lvm_id(uuid, lvm_id, None, False))
def get_object_by_lvm_id(self, lvm_id):
"""
Given an lvm identifier, return the object registered for it
:param lvm_id: The lvm identifier
"""
with self.rlock:
if lvm_id in self._id_to_object_path:
return self.get_object_by_path(self._id_to_object_path[lvm_id])
return None
def get_object_path_by_lvm_id(self, lvm_id):
"""
Given an lvm identifier, return the object path for it
:param lvm_id: The lvm identifier
:return: Object path or '/' if not found
"""
with self.rlock:
if lvm_id in self._id_to_object_path:
return self._id_to_object_path[lvm_id]
return '/'
def _uuid_verify(self, path, uuid, lvm_id):
"""
Ensure uuid is present for a successful lvm_id lookup
NOTE: Internal call, assumes under object manager lock
:param path: Path to object we looked up
:param uuid: lvm uuid to verify
:param lvm_id: lvm_id used to find object
:return: None
"""
# This gets called when we found an object based on lvm_id, ensure
# uuid is correct too, as they can change. There is no durable
# non-changeable name in lvm
if lvm_id != uuid:
if uuid and uuid not in self._id_to_object_path:
obj = self.get_object_by_path(path)
self._lookup_add(obj, path, lvm_id, uuid)
def _lvm_id_verify(self, path, uuid, lvm_id):
"""
Ensure lvm_id is present for a successful uuid lookup
NOTE: Internal call, assumes under object manager lock
:param path: Path to object we looked up
:param uuid: uuid used to find object
:param lvm_id: lvm_id to verify
:return: None
"""
# This gets called when we found an object based on uuid, ensure
# lvm_id is correct too, as they can change. There is no durable
# non-changeable name in lvm
if lvm_id != uuid:
if lvm_id and lvm_id not in self._id_to_object_path:
obj = self.get_object_by_path(path)
self._lookup_add(obj, path, lvm_id, uuid)
def _id_lookup(self, the_id):
path = None
if the_id:
# The _id_to_object_path contains hash keys for everything, so
# uuid and lvm_id
if the_id in self._id_to_object_path:
path = self._id_to_object_path[the_id]
else:
if "/" in the_id:
if the_id.startswith('/'):
# We could have a pv device path lookup that failed,
# lets try canonical form and try again.
canonical = os.path.realpath(the_id)
if canonical in self._id_to_object_path:
path = self._id_to_object_path[canonical]
else:
vg, lv = the_id.split("/", 1)
int_lvm_id = vg + "/" + ("[%s]" % lv)
if int_lvm_id in self._id_to_object_path:
path = self._id_to_object_path[int_lvm_id]
return path
def get_object_path_by_uuid_lvm_id(self, uuid, lvm_id, path_create=None,
gen_new=True):
"""
For a given lvm asset return the dbus object registered to it. If the
object is not found and gen_new == True and path_create is a valid
function we will create a new path, register it and return it.
:param uuid: The uuid for the lvm object
:param lvm_id: The lvm name
:param path_create: If true create an object path if not found
:param gen_new: The function used to create the new path
"""
with self.rlock:
assert lvm_id
assert uuid
if gen_new:
assert path_create
assert uuid != lvm_id
# Check for Manager.LookUpByLvmId query, we cannot
# check/verify/update the uuid and lvm_id lookups so don't!
if uuid == lvm_id:
path = self._id_lookup(lvm_id)
else:
# We have a uuid and a lvm_id we can do sanity checks to ensure
# that they are consistent
# If a PV is missing it's device path is '[unknown]'. When
# we see the lvm_id as such we will re-assign to None
if path_create == pv_obj_path_generate and \
lvm_id == '[unknown]':
lvm_id = None
# Lets check for the uuid first
path = self._id_lookup(uuid)
if path:
# Verify the lvm_id is sane
self._lvm_id_verify(path, uuid, lvm_id)
else:
# Unable to find by UUID, lets lookup by lvm_id
path = self._id_lookup(lvm_id)
if path:
# Verify the uuid is sane
self._uuid_verify(path, uuid, lvm_id)
else:
# We have exhausted all lookups, let's create if we can
if gen_new:
path = path_create()
self._lookup_add(None, path, lvm_id, uuid)
# print('get_object_path_by_lvm_id(%s, %s, %s, %s: return %s' %
# (uuid, lvm_id, str(path_create), str(gen_new), path))
return path
class ObjectManagerLock(object):
"""
The sole purpose of this class is to allow other code the ability to
lock the object manager using a `with` statement, eg.
with cfg.om.locked():
# Do stuff with object manager
This will ensure that the lock is always released (assuming this is done
correctly)
"""
def __init__(self, recursive_lock):
self._lock = recursive_lock
def __enter__(self):
# Acquire lock
self._lock.acquire()
# noinspection PyUnusedLocal
def __exit__(self, e_type, e_value, e_traceback):
# Release lock
self._lock.release()
self._lock = None