Synnefo » snf-ganeti

def CheckDiskAccessModeValidity(parameters):

  """Checks if the access parameter is legal.

  @see: L{CheckDiskAccessModeConsistency} for cluster consistency checks.

  @raise errors.OpPrereqError: if the check fails.

  """

  if constants.DT_RBD in parameters:

    access = parameters[constants.DT_RBD].get(constants.RBD_ACCESS,

                                              constants.DISK_KERNELSPACE)

    if access not in constants.DISK_VALID_ACCESS_MODES:

      valid_vals_str = utils.CommaJoin(constants.DISK_VALID_ACCESS_MODES)

      raise errors.OpPrereqError("Invalid value of '{d}:{a}': '{v}' (expected"

                                 " one of {o})".format(d=constants.DT_RBD,

                                                       a=constants.RBD_ACCESS,

                                                       v=access,

                                                       o=valid_vals_str))

def CheckDiskAccessModeConsistency(parameters, cfg, group=None):

  """Checks if the access param is consistent with the cluster configuration.

  @note: requires a configuration lock to run.

  @param parameters: the parameters to validate

  @param cfg: the cfg object of the cluster

  @param group: if set, only check for consistency within this group.

  @raise errors.OpPrereqError: if the LU attempts to change the access parameter

                               to an invalid value, such as "pink bunny".

  @raise errors.OpPrereqError: if the LU attempts to change the access parameter

                               to an inconsistent value, such as asking for RBD

                               userspace access to the chroot hypervisor.

  """

  CheckDiskAccessModeValidity(parameters)

  if constants.DT_RBD in parameters:

    access = parameters[constants.DT_RBD].get(constants.RBD_ACCESS,

                                              constants.DISK_KERNELSPACE)

    #Check the combination of instance hypervisor, disk template and access

    #protocol is sane.

    inst_uuids = cfg.GetNodeGroupInstances(group) if group else \

                 cfg.GetInstanceList()

    for entry in inst_uuids:

      #hyp, disk, access

      inst = cfg.GetInstanceInfo(entry)

      hv = inst.hypervisor

      dt = inst.disk_template

      #do not check for disk types that don't have this setting.

      if dt != constants.DT_RBD:

        continue

      if not IsValidDiskAccessModeCombination(hv, dt, access):

        raise errors.OpPrereqError("Instance {i}: cannot use '{a}' access"

                                   " setting with {h} hypervisor and {d} disk"

                                   " type.".format(i=inst.name,

                                                   a=access,

                                                   h=hv,

                                                   d=dt))

def IsValidDiskAccessModeCombination(hv, disk_template, mode):

  """Checks if an hypervisor can read a disk template with given mode.

  @param hv: the hypervisor that will access the data

  @param disk_template: the disk template the data is stored as

  @param mode: how the hypervisor should access the data

  @return: True if the hypervisor can read a given read disk_template

           in the specified mode.

  """

  if mode == constants.DISK_KERNELSPACE:

    return True

  if (hv == constants.HT_KVM and

      disk_template == constants.DT_RBD and

      mode == constants.DISK_USERSPACE):

    return True

  # Everything else:

  return False