text: # 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 dict specifying disk configuration
  
     It contains the following 3 required fields
  
        bus (disk_bus), dev (disk_dev), type (device_type)
  
     and possibly these optional fields: ('format', 'boot_index')
  
   * '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
  
  
  from nova import block_device
  from nova import exception
  from nova.i18n import _
  from nova.objects import base as obj_base
  from nova.objects import fields as obj_fields
  from nova.virt import configdrive
  from nova.virt import driver
  from nova.virt.libvirt import utils as libvirt_utils
  from nova.virt import osinfo
  
  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.InternalError(
              _("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,
                                 assigned_devices=None):
      """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.
  
         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
  
      if assigned_devices is None:
          assigned_devices = []
  
      max_dev = get_dev_count_for_disk_bus(bus)
      devs = range(max_dev)
  
      for idx in devs:
          disk_dev = dev_prefix + chr(ord('a') + idx)
          if not has_disk_dev(mapping, disk_dev):
              if disk_dev not in assigned_devices:
                  return disk_dev
  
      msg = _("No free disk device names for prefix '%s'") % dev_prefix
      raise exception.InternalError(msg)
  
  
  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']
          }
  
      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(instance,
                                   virt_type,
                                   image_meta,
                                   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 device_type == "disk":
          disk_bus = osinfo.HardwareProperties(image_meta).disk_model
      else:
          key = "hw_" + device_type + "_bus"
          disk_bus = image_meta.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 = obj_fields.VMMode.get_from_instance(instance)
          if guest_vm_mode == obj_fields.VMMode.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 (
                      obj_fields.Architecture.PPC,
                      obj_fields.Architecture.PPC64,
                      obj_fields.Architecture.PPCLE,
                      obj_fields.Architecture.PPC64LE,
                      obj_fields.Architecture.S390,
                      obj_fields.Architecture.S390X,
                      obj_fields.Architecture.AARCH64):
                  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 "scsi"
      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.startswith('hd'):
          return "ide"
      elif disk_dev.startswith('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.startswith('vd'):
          return "virtio"
      elif disk_dev.startswith('fd'):
          return "fdc"
      elif disk_dev.startswith('xvd'):
          return "xen"
      elif disk_dev.startswith('ubd'):
          return "uml"
      else:
          msg = _("Unable to determine disk bus for '%s'") % disk_dev[:1]
          raise exception.InternalError(msg)
  
  
  def get_next_disk_info(mapping, disk_bus,
                         device_type='disk',
                         boot_index=None,
                         assigned_devices=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,
                                            assigned_devices)
      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(instance, 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(instance, 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(instance, 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:
          # NOTE(mriedem): In case the image_meta object was constructed from
          # an empty dict, like in the case of evacuate, we have to first check
          # if disk_format is set on the ImageMeta object.
          if (image_meta.obj_attr_is_set('disk_format') and
                  image_meta.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'}
  
      if not get_device_name(root_bdm) and root_device_name:
          root_bdm = root_bdm.copy()
          # it can happen, eg for libvirt+Xen, that the root_device_name is
          # incompatible with the disk bus. In that case fix the root_device_name
          if virt_type == 'xen':
              dev_prefix = get_dev_prefix_for_disk_bus(disk_bus)
              if not root_device_name.startswith(dev_prefix):
                  letter = block_device.get_device_letter(root_device_name)
                  root_device_name = '%s%s' % (dev_prefix, letter)
          root_bdm['device_name'] = root_device_name
      return get_info_from_bdm(instance, 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 get_default_ephemeral_info(instance, disk_bus, block_device_info, mapping):
      ephemerals = driver.block_device_info_get_ephemerals(block_device_info)
      if not instance.ephemeral_gb or 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.
      """
  
      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
  
          if configdrive.required_by(instance):
              device_type = get_config_drive_type()
              disk_bus = get_disk_bus_for_device_type(instance,
                                                      virt_type,
                                                      image_meta,
                                                      device_type)
              config_info = get_next_disk_info(mapping,
                                               disk_bus,
                                               device_type)
              mapping['disk.config.rescue'] = config_info
  
          return 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)]
  
      # NOTE (ndipanov): root_bdm can be None when we boot from image
      # as there is no driver representation 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(
          instance, 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
      elif root_bdm:
          # NOTE (ft): If device name is not set in root bdm, root_info has a
          # generated one. We have to copy device name to root bdm to prevent its
          # second generation in loop through bdms. If device name is already
          # set, nothing is changed.
          update_bdm(root_bdm, root_info)
  
      default_eph = get_default_ephemeral_info(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(
              instance, 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(
              instance, virt_type, image_meta,
              swap, mapping, disk_bus)
          mapping['disk.swap'] = swap_info
          update_bdm(swap, swap_info)
      elif instance.get_flavor()['swap'] > 0:
          swap_info = get_next_disk_info(mapping, disk_bus,
              assigned_devices=pre_assigned_device_names)
          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 bdm in block_device_mapping:
          vol_info = get_info_from_bdm(
              instance, virt_type, image_meta, bdm, mapping,
              assigned_devices=pre_assigned_device_names)
          mapping[block_device.prepend_dev(vol_info['dev'])] = vol_info
          update_bdm(bdm, vol_info)
  
      if configdrive.required_by(instance):
          device_type = get_config_drive_type()
          disk_bus = get_disk_bus_for_device_type(instance,
                                                  virt_type,
                                                  image_meta,
                                                  device_type)
          config_info = get_next_disk_info(mapping,
                                           disk_bus,
                                           device_type)
          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(instance, virt_type,
                                              image_meta, "disk")
      cdrom_bus = get_disk_bus_for_device_type(instance, virt_type,
                                               image_meta, "cdrom")
      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 disk_info['mapping'].items()
                      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)
  