# Copyright (C) 2012-2013 Red Hat, Inc. # # 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. """ Handling of block device information and mapping. This module contains helper methods for interpreting the block device information and determining the suitable mapping to guest devices and libvirt XML. Throughout these methods there are a number of standard variables / types used * 'mapping': a dict contains the storage device mapping. For the default disk types it will contain the following keys & values: 'disk' -> disk_info 'disk.rescue' -> disk_info 'disk.local' -> disk_info 'disk.swap' -> disk_info 'disk.config' -> disk_info If any of the default disks are overridden by the block device info mappings, the hash value will be None For any ephemeral device there will also be a dict entry 'disk.eph$NUM' -> disk_info For any volume device there will also be a dict entry: $path -> disk_info Finally a special key will refer to the root device: 'root' -> disk_info * 'disk_info': a tuple specifying disk configuration It contains the following 3 fields (disk bus, disk dev, device type) and possibly these optional fields: ('format',) * 'disk_bus': the guest bus type ('ide', 'virtio', 'scsi', etc) * 'disk_dev': the device name 'vda', 'hdc', 'sdf', 'xvde' etc * 'device_type': type of device eg 'disk', 'cdrom', 'floppy' * 'format': Which format to apply to the device if applicable * 'boot_index': Number designating the boot order of the device """ import itertools import operator from oslo_config import cfg import six from nova import block_device from nova.compute import arch from nova.compute import vm_mode from nova import exception from nova.i18n import _ from nova.objects import base as obj_base from nova.virt import configdrive from nova.virt import driver from nova.virt.libvirt import utils as libvirt_utils CONF = cfg.CONF SUPPORTED_DEVICE_TYPES = ('disk', 'cdrom', 'floppy', 'lun') BOOT_DEV_FOR_TYPE = {'disk': 'hd', 'cdrom': 'cdrom', 'floppy': 'fd'} def has_disk_dev(mapping, disk_dev): """Determine if a disk device name has already been used. Looks at all the keys in mapping to see if any corresponding disk_info tuple has a device name matching disk_dev Returns True if the disk_dev is in use. """ for disk in mapping: info = mapping[disk] if info['dev'] == disk_dev: return True return False def get_dev_prefix_for_disk_bus(disk_bus): """Determine the dev prefix for a disk bus. Determine the dev prefix to be combined with a disk number to fix a disk_dev. eg 'hd' for 'ide' bus can be used to form a disk dev 'hda' Returns the dev prefix or raises an exception if the disk bus is unknown. """ if CONF.libvirt.disk_prefix: return CONF.libvirt.disk_prefix if disk_bus == "ide": return "hd" elif disk_bus == "virtio": return "vd" elif disk_bus == "xen": return "xvd" elif disk_bus == "scsi": return "sd" elif disk_bus == "usb": return "sd" elif disk_bus == "fdc": return "fd" elif disk_bus == "uml": return "ubd" elif disk_bus == "lxc": return None elif disk_bus == "sata": return "sd" else: raise exception.NovaException( _("Unable to determine disk prefix for %s") % disk_bus) def get_dev_count_for_disk_bus(disk_bus): """Determine the number disks supported. Determine how many disks can be supported in a single VM for a particular disk bus. Returns the number of disks supported. """ if disk_bus == "ide": return 4 else: return 26 def find_disk_dev_for_disk_bus(mapping, bus, last_device=False): """Identify a free disk dev name for a bus. Determines the possible disk dev names for the bus, and then checks them in order until it identifies one that is not yet used in the disk mapping. If 'last_device' is set, it will only consider the last available disk dev name. Returns the chosen disk_dev name, or raises an exception if none is available. """ dev_prefix = get_dev_prefix_for_disk_bus(bus) if dev_prefix is None: return None max_dev = get_dev_count_for_disk_bus(bus) if last_device: devs = [max_dev - 1] else: devs = range(max_dev) for idx in devs: disk_dev = dev_prefix + chr(ord('a') + idx) if not has_disk_dev(mapping, disk_dev): return disk_dev raise exception.NovaException( _("No free disk device names for prefix '%s'"), dev_prefix) def is_disk_bus_valid_for_virt(virt_type, disk_bus): valid_bus = { 'qemu': ['virtio', 'scsi', 'ide', 'usb', 'fdc'], 'kvm': ['virtio', 'scsi', 'ide', 'usb', 'fdc'], 'xen': ['xen', 'ide'], 'uml': ['uml'], 'lxc': ['lxc'], 'parallels': ['ide', 'scsi', 'sata'] } if virt_type not in valid_bus: raise exception.UnsupportedVirtType(virt=virt_type) return disk_bus in valid_bus[virt_type] def get_disk_bus_for_device_type(virt_type, image_meta, device_type="disk", instance=None): """Determine the best disk bus to use for a device type. Considering the currently configured virtualization type, return the optimal disk_bus to use for a given device type. For example, for a disk on KVM it will return 'virtio', while for a CDROM it will return 'ide' on x86_64 and 'scsi' on ppc64. Returns the disk_bus, or returns None if the device type is not supported for this virtualization """ # Prefer a disk bus set against the image first of all key = "hw_" + device_type + "_bus" disk_bus = image_meta.get('properties', {}).get(key) if disk_bus is not None: if not is_disk_bus_valid_for_virt(virt_type, disk_bus): raise exception.UnsupportedHardware(model=disk_bus, virt=virt_type) return disk_bus # Otherwise pick a hypervisor default disk bus if virt_type == "uml": if device_type == "disk": return "uml" elif virt_type == "lxc": return "lxc" elif virt_type == "xen": guest_vm_mode = None if instance: guest_vm_mode = vm_mode.get_from_instance(instance) if guest_vm_mode == vm_mode.HVM: return "ide" else: return "xen" elif virt_type in ("qemu", "kvm"): if device_type == "cdrom": guestarch = libvirt_utils.get_arch(image_meta) if guestarch in (arch.PPC, arch.PPC64, arch.S390, arch.S390X): return "scsi" else: return "ide" elif device_type == "disk": return "virtio" elif device_type == "floppy": return "fdc" elif virt_type == "parallels": if device_type == "cdrom": return "ide" elif device_type == "disk": return "sata" else: # If virt-type not in list then it is unsupported raise exception.UnsupportedVirtType(virt=virt_type) return None def get_disk_bus_for_disk_dev(virt_type, disk_dev): """Determine the disk bus for a disk device. Given a disk device like 'hda', 'sdf', 'xvdb', etc guess what the most appropriate disk bus is for the currently configured virtualization technology Returns the disk bus, or raises an Exception if the disk device prefix is unknown. """ if disk_dev[:2] == 'hd': return "ide" elif disk_dev[:2] == 'sd': # Reverse mapping 'sd' is not reliable # there are many possible mappings. So # this picks the most likely mappings if virt_type == "xen": return "xen" elif virt_type == "parallels": return "sata" else: return "scsi" elif disk_dev[:2] == 'vd': return "virtio" elif disk_dev[:2] == 'fd': return "fdc" elif disk_dev[:3] == 'xvd': return "xen" elif disk_dev[:3] == 'ubd': return "uml" else: raise exception.NovaException( _("Unable to determine disk bus for '%s'") % disk_dev[:1]) def get_next_disk_info(mapping, disk_bus, device_type='disk', last_device=False, boot_index=None): """Determine the disk info for the next device on disk_bus. Considering the disks already listed in the disk mapping, determine the next available disk dev that can be assigned for the disk bus. Returns the disk_info for the next available disk. """ disk_dev = find_disk_dev_for_disk_bus(mapping, disk_bus, last_device) info = {'bus': disk_bus, 'dev': disk_dev, 'type': device_type} if boot_index is not None and boot_index >= 0: info['boot_index'] = str(boot_index) return info def get_eph_disk(index): return 'disk.eph' + str(index) def get_config_drive_type(): """Determine the type of config drive. If config_drive_format is set to iso9660 then the config drive will be 'cdrom', otherwise 'disk'. Returns a string indicating the config drive type. """ if CONF.config_drive_format == 'iso9660': config_drive_type = 'cdrom' elif CONF.config_drive_format == 'vfat': config_drive_type = 'disk' else: raise exception.ConfigDriveUnknownFormat( format=CONF.config_drive_format) return config_drive_type def get_info_from_bdm(virt_type, image_meta, bdm, mapping=None, disk_bus=None, dev_type=None, allowed_types=None, assigned_devices=None): mapping = mapping or {} allowed_types = allowed_types or SUPPORTED_DEVICE_TYPES device_name = block_device.strip_dev(get_device_name(bdm)) bdm_type = bdm.get('device_type') or dev_type if bdm_type not in allowed_types: bdm_type = 'disk' bdm_bus = bdm.get('disk_bus') or disk_bus if not is_disk_bus_valid_for_virt(virt_type, bdm_bus): if device_name: bdm_bus = get_disk_bus_for_disk_dev(virt_type, device_name) else: bdm_bus = get_disk_bus_for_device_type(virt_type, image_meta, bdm_type) if not device_name: if assigned_devices: padded_mapping = {dev: {'dev': dev} for dev in assigned_devices} padded_mapping.update(mapping) else: padded_mapping = mapping device_name = find_disk_dev_for_disk_bus(padded_mapping, bdm_bus) bdm_info = {'bus': bdm_bus, 'dev': device_name, 'type': bdm_type} bdm_format = bdm.get('guest_format') if bdm_format: bdm_info.update({'format': bdm_format}) boot_index = bdm.get('boot_index') if boot_index is not None and boot_index >= 0: # NOTE(ndipanov): libvirt starts ordering from 1, not 0 bdm_info['boot_index'] = str(boot_index + 1) return bdm_info def get_device_name(bdm): """Get the device name if present regardless of the bdm format.""" if isinstance(bdm, obj_base.NovaObject): return bdm.device_name else: return bdm.get('device_name') or bdm.get('mount_device') def get_root_info(virt_type, image_meta, root_bdm, disk_bus, cdrom_bus, root_device_name=None): # NOTE (ndipanov): This is a hack to avoid considering an image # BDM with local target, as we don't support them # yet. Only applies when passed non-driver format no_root_bdm = (not root_bdm or ( root_bdm.get('source_type') == 'image' and root_bdm.get('destination_type') == 'local')) if no_root_bdm: if image_meta.get('disk_format') == 'iso': root_device_bus = cdrom_bus root_device_type = 'cdrom' else: root_device_bus = disk_bus root_device_type = 'disk' if root_device_name: root_device_bus = get_disk_bus_for_disk_dev(virt_type, root_device_name) else: root_device_name = find_disk_dev_for_disk_bus({}, root_device_bus) return {'bus': root_device_bus, 'type': root_device_type, 'dev': block_device.strip_dev(root_device_name), 'boot_index': '1'} else: if not get_device_name(root_bdm) and root_device_name: root_bdm = root_bdm.copy() root_bdm['device_name'] = root_device_name return get_info_from_bdm(virt_type, image_meta, root_bdm, {}, disk_bus) def default_device_names(virt_type, context, instance, block_device_info, image_meta): get_disk_info(virt_type, instance, image_meta, block_device_info) for driver_bdm in itertools.chain(block_device_info['ephemerals'], [block_device_info['swap']] if block_device_info['swap'] else [], block_device_info['block_device_mapping']): driver_bdm.save() def has_default_ephemeral(instance, disk_bus, block_device_info, mapping): ephemerals = driver.block_device_info_get_ephemerals(block_device_info) if instance.ephemeral_gb <= 0 or ephemerals: return None else: info = get_next_disk_info(mapping, disk_bus) if block_device.volume_in_mapping(info['dev'], block_device_info): return None return info def update_bdm(bdm, info): device_name_field = ('device_name' if 'device_name' in bdm else 'mount_device') # Do not update the device name if it was already present bdm.update(dict(zip((device_name_field, 'disk_bus', 'device_type'), ((bdm.get(device_name_field) or block_device.prepend_dev(info['dev'])), info['bus'], info['type'])))) def get_disk_mapping(virt_type, instance, disk_bus, cdrom_bus, image_meta, block_device_info=None, rescue=False): """Determine how to map default disks to the virtual machine. This is about figuring out whether the default 'disk', 'disk.local', 'disk.swap' and 'disk.config' images have been overridden by the block device mapping. Returns the guest disk mapping for the devices. """ inst_type = instance.get_flavor() mapping = {} pre_assigned_device_names = \ [block_device.strip_dev(get_device_name(bdm)) for bdm in itertools.chain( driver.block_device_info_get_ephemerals(block_device_info), [driver.block_device_info_get_swap(block_device_info)], driver.block_device_info_get_mapping(block_device_info)) if get_device_name(bdm)] if rescue: rescue_info = get_next_disk_info(mapping, disk_bus, boot_index=1) mapping['disk.rescue'] = rescue_info mapping['root'] = rescue_info os_info = get_next_disk_info(mapping, disk_bus) mapping['disk'] = os_info return mapping # NOTE (ndipanov): root_bdm can be None when we boot from image # as there is no driver represenation of local targeted images # and they will not be in block_device_info list. root_bdm = block_device.get_root_bdm( driver.block_device_info_get_mapping(block_device_info)) root_device_name = block_device.strip_dev( driver.block_device_info_get_root(block_device_info)) root_info = get_root_info(virt_type, image_meta, root_bdm, disk_bus, cdrom_bus, root_device_name) mapping['root'] = root_info # NOTE (ndipanov): This implicitly relies on image->local BDMs not # being considered in the driver layer - so missing # bdm with boot_index 0 means - use image, unless it was # overridden. This can happen when using legacy syntax and # no root_device_name is set on the instance. if not root_bdm and not block_device.volume_in_mapping(root_info['dev'], block_device_info): mapping['disk'] = root_info default_eph = has_default_ephemeral(instance, disk_bus, block_device_info, mapping) if default_eph: mapping['disk.local'] = default_eph for idx, eph in enumerate(driver.block_device_info_get_ephemerals( block_device_info)): eph_info = get_info_from_bdm( virt_type, image_meta, eph, mapping, disk_bus, assigned_devices=pre_assigned_device_names) mapping[get_eph_disk(idx)] = eph_info update_bdm(eph, eph_info) swap = driver.block_device_info_get_swap(block_device_info) if swap and swap.get('swap_size', 0) > 0: swap_info = get_info_from_bdm(virt_type, image_meta, swap, mapping, disk_bus) mapping['disk.swap'] = swap_info update_bdm(swap, swap_info) elif inst_type['swap'] > 0: swap_info = get_next_disk_info(mapping, disk_bus) if not block_device.volume_in_mapping(swap_info['dev'], block_device_info): mapping['disk.swap'] = swap_info block_device_mapping = driver.block_device_info_get_mapping( block_device_info) for vol in block_device_mapping: vol_info = get_info_from_bdm( virt_type, image_meta, vol, mapping, assigned_devices=pre_assigned_device_names) mapping[block_device.prepend_dev(vol_info['dev'])] = vol_info update_bdm(vol, vol_info) if configdrive.required_by(instance): device_type = get_config_drive_type() disk_bus = get_disk_bus_for_device_type(virt_type, image_meta, device_type, instance=instance) config_info = get_next_disk_info(mapping, disk_bus, device_type, last_device=True) mapping['disk.config'] = config_info return mapping def get_disk_info(virt_type, instance, image_meta, block_device_info=None, rescue=False): """Determine guest disk mapping info. This is a wrapper around get_disk_mapping, which also returns the chosen disk_bus and cdrom_bus. The returned data is in a dict - disk_bus: the bus for harddisks - cdrom_bus: the bus for CDROMs - mapping: the disk mapping Returns the disk mapping disk. """ disk_bus = get_disk_bus_for_device_type(virt_type, image_meta, "disk", instance=instance) cdrom_bus = get_disk_bus_for_device_type(virt_type, image_meta, "cdrom", instance=instance) mapping = get_disk_mapping(virt_type, instance, disk_bus, cdrom_bus, image_meta, block_device_info, rescue) return {'disk_bus': disk_bus, 'cdrom_bus': cdrom_bus, 'mapping': mapping} def get_boot_order(disk_info): boot_mapping = (info for name, info in six.iteritems(disk_info['mapping']) if name != 'root' and info.get('boot_index') is not None) boot_devs_dup = (BOOT_DEV_FOR_TYPE[dev['type']] for dev in sorted(boot_mapping, key=operator.itemgetter('boot_index'))) def uniq(lst): s = set() return [el for el in lst if el not in s and not s.add(el)] return uniq(boot_devs_dup)