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OpenStack Study: blockinfo.py**** CubicPower OpenStack Study **** 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
**** CubicPower OpenStack Study **** 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": # Two possible mappings for Xen, xvda or sda # which are interchangeable, so we pick sda return "sd" 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 else: raise exception.NovaException( _("Unable to determine disk prefix for %s") % disk_bus)
**** CubicPower OpenStack Study **** 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
**** CubicPower OpenStack Study **** 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)
**** CubicPower OpenStack Study **** 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'], } if virt_type not in valid_bus: raise exception.UnsupportedVirtType(virt=virt_type) return disk_bus in valid_bus[virt_type]
**** CubicPower OpenStack Study **** def get_disk_bus_for_device_type(virt_type, image_meta=None, device_type="disk"): """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 if image_meta: 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": if device_type == "cdrom": return "ide" elif device_type == "disk": return "xen" elif virt_type in ("qemu", "kvm"): if device_type == "cdrom": arch = libvirt_utils.get_arch(image_meta) if arch in ("ppc", "ppc64"): return "scsi" else: return "ide" elif device_type == "disk": return "virtio" elif device_type == "floppy": return "fdc" return None
**** CubicPower OpenStack Study **** 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" 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])
**** CubicPower OpenStack Study **** 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
**** CubicPower OpenStack Study **** def get_eph_disk(index): return 'disk.eph' + str(index)
**** CubicPower OpenStack Study **** 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
**** CubicPower OpenStack Study **** def get_info_from_bdm(virt_type, bdm, mapping={}, disk_bus=None, dev_type=None, allowed_types=None, assigned_devices=None): 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, None, bdm_type) if not device_name: if assigned_devices: padded_mapping = dict((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
**** CubicPower OpenStack Study **** def get_device_name(bdm): """Get the device name if present regardless of the bdm format.""" if isinstance(bdm, block_device_obj.BlockDeviceMapping): return bdm.device_name else: return bdm.get('device_name') or bdm.get('mount_device')
**** CubicPower OpenStack Study **** 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 and 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, root_bdm, {}, disk_bus)
**** CubicPower OpenStack Study **** def default_device_names(virt_type, context, instance, root_device_name, ephemerals, swap, block_device_mapping): block_device_info = { 'root_device_name': root_device_name, 'swap': driver_block_device.get_swap( driver_block_device.convert_swap(swap)), 'ephemerals': driver_block_device.convert_ephemerals(ephemerals), 'block_device_mapping': ( driver_block_device.convert_volumes( block_device_mapping) + driver_block_device.convert_snapshots( block_device_mapping)) } get_disk_info(virt_type, instance, 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(context)
**** CubicPower OpenStack Study **** 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
**** CubicPower OpenStack Study **** 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']))))
**** CubicPower OpenStack Study **** def get_disk_mapping(virt_type, instance, disk_bus, cdrom_bus, block_device_info=None, image_meta=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 = flavors.extract_flavor(instance) 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 virt_type == "lxc": # NOTE(zul): This information is not used by the libvirt driver # however we need to populate mapping so the image can be # created when the instance is started. This can # be removed when we convert LXC to use block devices. root_disk_bus = disk_bus root_device_type = 'disk' root_info = get_next_disk_info(mapping, root_disk_bus, root_device_type, boot_index=1) mapping['root'] = root_info mapping['disk'] = root_info return mapping 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 # overriden. 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, 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, 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, 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) config_info = get_next_disk_info(mapping, disk_bus, device_type, last_device=True) mapping['disk.config'] = config_info return mapping
**** CubicPower OpenStack Study **** def get_disk_info(virt_type, instance, block_device_info=None, image_meta=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") cdrom_bus = get_disk_bus_for_device_type(virt_type, image_meta, "cdrom") mapping = get_disk_mapping(virt_type, instance, disk_bus, cdrom_bus, block_device_info, image_meta, rescue) return {'disk_bus': disk_bus, 'cdrom_bus': cdrom_bus, 'mapping': mapping}
**** CubicPower OpenStack Study **** def get_boot_order(disk_info): boot_mapping = (info for name, info in disk_info['mapping'].iteritems() 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)
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