Synnefo » snf-ganeti

import stat

class PersistentBlockDevice(BlockDev):

  """A block device with persistent node

  May be either directly attached, or exposed through DM (e.g. dm-multipath).

  udev helpers are probably required to give persistent, human-friendly

  names.

  For the time being, pathnames are required to lie under /dev.

  """

  def __init__(self, unique_id, children, size):

    """Attaches to a static block device.

    The unique_id is a path under /dev.

    """

    super(PersistentBlockDevice, self).__init__(unique_id, children, size)

    if not isinstance(unique_id, (tuple, list)) or len(unique_id) != 2:

      raise ValueError("Invalid configuration data %s" % str(unique_id))

    self.dev_path = unique_id[1]

    if not os.path.realpath(self.dev_path).startswith('/dev/'):

      raise ValueError("Full path '%s' lies outside /dev" %

                              os.path.realpath(self.dev_path))

    # TODO: this is just a safety guard checking that we only deal with devices

    # we know how to handle. In the future this will be integrated with

    # external storage backends and possible values will probably be collected

    # from the cluster configuration.

    if unique_id[0] != constants.BLOCKDEV_DRIVER_MANUAL:

      raise ValueError("Got persistent block device of invalid type: %s" %

                       unique_id[0])

    self.major = self.minor = None

    self.Attach()

  @classmethod

  def Create(cls, unique_id, children, size):

    """Create a new device

    This is a noop, we only return a PersistentBlockDevice instance

    """

    return PersistentBlockDevice(unique_id, children, 0)

  def Remove(self):

    """Remove a device

    This is a noop

    """

    pass

  def Rename(self, new_id):

    """Rename this device.

    """

    _ThrowError("Rename is not supported for PersistentBlockDev storage")

  def Attach(self):

    """Attach to an existing block device.

    """

    self.attached = False

    try:

      st = os.stat(self.dev_path)

    except OSError, err:

      logging.error("Error stat()'ing %s: %s", self.dev_path, str(err))

      return False

    if not stat.S_ISBLK(st.st_mode):

      logging.error("%s is not a block device", self.dev_path)

      return False

    self.major = os.major(st.st_rdev)

    self.minor = os.minor(st.st_rdev)

    self.attached = True

    return True

  def Assemble(self):

    """Assemble the device.

    """

    pass

  def Shutdown(self):

    """Shutdown the device.

    """

    pass

  def Open(self, force=False):

    """Make the device ready for I/O.

    """

    pass

  def Close(self):

    """Notifies that the device will no longer be used for I/O.

    """

    pass

  def Grow(self, amount):

    """Grow the logical volume.

    """

    _ThrowError("Grow is not supported for PersistentBlockDev storage")

  constants.LD_BLOCKDEV: PersistentBlockDevice,