gantt/nova/block_device.py
Vishvananda Ishaya 0bc5d56093 Allow nova to guess device if not passed to attach
partial fix for bug 1004328

Only the xen hypervisor actually respects the device name that
is passed in attach_volume. For other hypervisors it makes much
more sense to automatically generate a unique name.

This patch generates a non-conflicting device name if one is not
passed to attach_volume. It also validates the passed in volume
name to make sure another device isn't already attached there.

A corresponding change to novaclient and horizon will greatly
improve the user experience of attaching a volume.

It moves some common code out of metadata/base so that it can
be used to get a list of block devices. The code was functionally
tested as well and block device name generation works properly.

This adds a new method to the rpcapi to validate a device name. It
also adds server_id to the volumes extension, since it was omitted
by mistake.

The next step is to modify the libvirt driver to match the serial
number of the device to the volume uuid so that the volume can
always be found at /dev/disk/by-id/virtio-<uuid>.

DocImpact

Change-Id: I0b9454fc50a5c93b4aea38545dcee98f68d7e511
2012-08-15 14:22:05 -07:00

134 lines
3.9 KiB
Python

# vim: tabstop=4 shiftwidth=4 softtabstop=4
# Copyright 2011 Isaku Yamahata <yamahata@valinux co jp>
# 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 re
DEFAULT_ROOT_DEV_NAME = '/dev/sda1'
_DEFAULT_MAPPINGS = {'ami': 'sda1',
'ephemeral0': 'sda2',
'root': DEFAULT_ROOT_DEV_NAME,
'swap': 'sda3'}
def properties_root_device_name(properties):
"""get root device name from image meta data.
If it isn't specified, return None.
"""
root_device_name = None
# NOTE(yamahata): see image_service.s3.s3create()
for bdm in properties.get('mappings', []):
if bdm['virtual'] == 'root':
root_device_name = bdm['device']
# NOTE(yamahata): register_image's command line can override
# <machine>.manifest.xml
if 'root_device_name' in properties:
root_device_name = properties['root_device_name']
return root_device_name
_ephemeral = re.compile('^ephemeral(\d|[1-9]\d+)$')
def is_ephemeral(device_name):
return _ephemeral.match(device_name)
def ephemeral_num(ephemeral_name):
assert is_ephemeral(ephemeral_name)
return int(_ephemeral.sub('\\1', ephemeral_name))
def is_swap_or_ephemeral(device_name):
return device_name == 'swap' or is_ephemeral(device_name)
def mappings_prepend_dev(mappings):
"""Prepend '/dev/' to 'device' entry of swap/ephemeral virtual type"""
for m in mappings:
virtual = m['virtual']
if (is_swap_or_ephemeral(virtual) and
(not m['device'].startswith('/'))):
m['device'] = '/dev/' + m['device']
return mappings
_dev = re.compile('^/dev/')
def strip_dev(device_name):
"""remove leading '/dev/'"""
return _dev.sub('', device_name) if device_name else device_name
_pref = re.compile('^((x?v|s)d)')
def strip_prefix(device_name):
""" remove both leading /dev/ and xvd or sd or vd """
device_name = strip_dev(device_name)
return _pref.sub('', device_name)
def instance_block_mapping(instance, bdms):
root_device_name = instance['root_device_name']
if root_device_name is None:
return _DEFAULT_MAPPINGS
mappings = {}
mappings['ami'] = strip_dev(root_device_name)
mappings['root'] = root_device_name
default_ephemeral_device = instance.get('default_ephemeral_device')
if default_ephemeral_device:
mappings['ephemeral0'] = default_ephemeral_device
default_swap_device = instance.get('default_swap_device')
if default_swap_device:
mappings['swap'] = default_swap_device
ebs_devices = []
# 'ephemeralN', 'swap' and ebs
for bdm in bdms:
if bdm['no_device']:
continue
# ebs volume case
if (bdm['volume_id'] or bdm['snapshot_id']):
ebs_devices.append(bdm['device_name'])
continue
virtual_name = bdm['virtual_name']
if not virtual_name:
continue
if is_swap_or_ephemeral(virtual_name):
mappings[virtual_name] = bdm['device_name']
# NOTE(yamahata): I'm not sure how ebs device should be numbered.
# Right now sort by device name for deterministic
# result.
if ebs_devices:
nebs = 0
ebs_devices.sort()
for ebs in ebs_devices:
mappings['ebs%d' % nebs] = ebs
nebs += 1
return mappings