openstack
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nova
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nova/nova/virt/libvirt/lvm.py

279 lines
9.5 KiB
Python
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# Copyright 2010 United States Government as represented by the
# Administrator of the National Aeronautics and Space Administration.
# All Rights Reserved.
# Copyright (c) 2010 Citrix Systems, Inc.
# Copyright (c) 2011 Piston Cloud Computing, Inc
# Copyright (c) 2011 OpenStack Foundation
# (c) Copyright 2013 Hewlett-Packard Development Company, L.P.
#
# 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 functools
from oslo.config import cfg
from oslo.utils import units
from oslo_concurrency import processutils
import six
from nova import exception
from nova.i18n import _
from nova.i18n import _LE
from nova.i18n import _LW
from nova.openstack.common import log as logging
from nova import utils as nova_utils
from nova.virt.libvirt import utils
lvm_opts = [
cfg.StrOpt('volume_clear',
default='zero',
help='Method used to wipe old volumes (valid options are: '
'none, zero, shred)'),
cfg.IntOpt('volume_clear_size',
default=0,
help='Size in MiB to wipe at start of old volumes. 0 => all'),
]
CONF = cfg.CONF
CONF.register_opts(lvm_opts, 'libvirt')
CONF.import_opt('instances_path', 'nova.compute.manager')
LOG = logging.getLogger(__name__)
@nova_utils.expects_func_args('path')
def wrap_no_device_error(function):
"""Wraps a method to catch exceptions related to volume BDM not found.
This decorator wraps a method to catch ProcessExecutionError having to do
with a missing volume block device mapping. It translates the error to a
VolumeBDMPathNotFound exception.
"""
@functools.wraps(function)
def decorated_function(path):
try:
return function(path)
except processutils.ProcessExecutionError as e:
if 'No such device or address' in e.stderr:
raise exception.VolumeBDMPathNotFound(path=path)
else:
raise
return decorated_function
def create_volume(vg, lv, size, sparse=False):
"""Create LVM image.
Creates a LVM image with given size.
:param vg: existing volume group which should hold this image
:param lv: name for this image (logical volume)
:size: size of image in bytes
:sparse: create sparse logical volume
"""
vg_info = get_volume_group_info(vg)
free_space = vg_info['free']
def check_size(vg, lv, size):
if size > free_space:
raise RuntimeError(_('Insufficient Space on Volume Group %(vg)s.'
' Only %(free_space)db available,'
' but %(size)db required'
' by volume %(lv)s.') %
{'vg': vg,
'free_space': free_space,
'size': size,
'lv': lv})
if sparse:
preallocated_space = 64 * units.Mi
check_size(vg, lv, preallocated_space)
if free_space < size:
LOG.warn(_LW('Volume group %(vg)s will not be able'
' to hold sparse volume %(lv)s.'
' Virtual volume size is %(size)db,'
' but free space on volume group is'
' only %(free_space)db.'),
{'vg': vg,
'free_space': free_space,
'size': size,
'lv': lv})
cmd = ('lvcreate', '-L', '%db' % preallocated_space,
'--virtualsize', '%db' % size, '-n', lv, vg)
else:
check_size(vg, lv, size)
cmd = ('lvcreate', '-L', '%db' % size, '-n', lv, vg)
utils.execute(*cmd, run_as_root=True, attempts=3)
def get_volume_group_info(vg):
"""Return free/used/total space info for a volume group in bytes
:param vg: volume group name
:returns: A dict containing:
:total: How big the filesystem is (in bytes)
:free: How much space is free (in bytes)
:used: How much space is used (in bytes)
"""
out, err = utils.execute('vgs', '--noheadings', '--nosuffix',
'--separator', '|',
'--units', 'b', '-o', 'vg_size,vg_free', vg,
run_as_root=True)
info = out.split('|')
if len(info) != 2:
raise RuntimeError(_("vg %s must be LVM volume group") % vg)
return {'total': int(info[0]),
'free': int(info[1]),
'used': int(info[0]) - int(info[1])}
def list_volumes(vg):
"""List logical volumes paths for given volume group.
:param vg: volume group name
:returns: Return a logical volume list for given volume group
: Data format example
: ['volume-aaa', 'volume-bbb', 'volume-ccc']
"""
out, err = utils.execute('lvs', '--noheadings', '-o', 'lv_name', vg,
run_as_root=True)
return [line.strip() for line in out.splitlines()]
def volume_info(path):
"""Get logical volume info.
:param path: logical volume path
:returns: Return a dict object including info of given logical volume
: Data format example
: {'#Seg': '1', 'Move': '', 'Log': '', 'Meta%': '', 'Min': '-1',
: ...
: 'Free': '9983', 'LV': 'volume-aaa', 'Host': 'xyz.com',
: 'Active': 'active', 'Path': '/dev/vg/volume-aaa', '#LV': '3',
: 'Maj': '-1', 'VSize': '50.00g', 'VFree': '39.00g', 'Pool': '',
: 'VG Tags': '', 'KMaj': '253', 'Convert': '', 'LProfile': '',
: '#Ext': '12799', 'Attr': '-wi-a-----', 'VG': 'vg',
: ...
: 'LSize': '1.00g', '#PV': '1', '#VMdaCps': 'unmanaged'}
"""
out, err = utils.execute('lvs', '-o', 'vg_all,lv_all',
'--separator', '|', path, run_as_root=True)
info = [line.split('|') for line in out.splitlines()]
if len(info) != 2:
raise RuntimeError(_("Path %s must be LVM logical volume") % path)
return dict(zip(*info))
@wrap_no_device_error
def get_volume_size(path):
"""Get logical volume size in bytes.
:param path: logical volume path
:raises: processutils.ProcessExecutionError if getting the volume size
fails in some unexpected way.
:raises: exception.VolumeBDMPathNotFound if the volume path does not exist.
"""
out, _err = utils.execute('blockdev', '--getsize64', path,
run_as_root=True)
return int(out)
def _zero_volume(path, volume_size):
"""Write zeros over the specified path
:param path: logical volume path
:param size: number of zeros to write
"""
bs = units.Mi
direct_flags = ('oflag=direct',)
sync_flags = ()
remaining_bytes = volume_size
# The loop efficiently writes zeros using dd,
# and caters for versions of dd that don't have
# the easier to use iflag=count_bytes option.
while remaining_bytes:
zero_blocks = remaining_bytes / bs
seek_blocks = (volume_size - remaining_bytes) / bs
zero_cmd = ('dd', 'bs=%s' % bs,
'if=/dev/zero', 'of=%s' % path,
'seek=%s' % seek_blocks, 'count=%s' % zero_blocks)
zero_cmd += direct_flags
zero_cmd += sync_flags
if zero_blocks:
utils.execute(*zero_cmd, run_as_root=True)
remaining_bytes %= bs
bs /= units.Ki # Limit to 3 iterations
# Use O_DIRECT with initial block size and fdatasync otherwise
direct_flags = ()
sync_flags = ('conv=fdatasync',)
def clear_volume(path):
"""Obfuscate the logical volume.
:param path: logical volume path
"""
volume_clear = CONF.libvirt.volume_clear
if volume_clear not in ('none', 'shred', 'zero'):
LOG.error(_LE("ignoring unrecognized volume_clear='%s' value"),
volume_clear)
volume_clear = 'zero'
if volume_clear == 'none':
return
volume_clear_size = int(CONF.libvirt.volume_clear_size) * units.Mi
volume_size = get_volume_size(path)
if volume_clear_size != 0 and volume_clear_size < volume_size:
volume_size = volume_clear_size
if volume_clear == 'zero':
# NOTE(p-draigbrady): we could use shred to do the zeroing
# with -n0 -z, however only versions >= 8.22 perform as well as dd
_zero_volume(path, volume_size)
elif volume_clear == 'shred':
utils.execute('shred', '-n3', '-s%d' % volume_size, path,
run_as_root=True)
else:
raise exception.Invalid(_("volume_clear='%s' is not handled")
% volume_clear)
def remove_volumes(paths):
"""Remove one or more logical volume."""
errors = []
for path in paths:
clear_volume(path)
lvremove = ('lvremove', '-f', path)
try:
utils.execute(*lvremove, attempts=3, run_as_root=True)
except processutils.ProcessExecutionError as exp:
errors.append(six.text_type(exp))
if errors:
raise exception.VolumesNotRemoved(reason=(', ').join(errors))
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