openstack-cinder-虚机挂载云盘cinder侧过程以及源码分析

本文基于openstack Stein 版本

上文分析nova挂载云盘过程中，提到调用cinder initialize_connection, 返回volume 的连接信息，比如rbd ceph 的connection info, 同时在 _parse_connection_options 中基于volume type 添加cinder io qos 信息

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cinder.volume.manager.VolumeManager.initialize_connection
def initialize_connection(self, context, volume, connector):
   ...............................................
        try:
            conn_info = self.driver.initialize_connection(volume, connector)
        except Exception as err:
            err_msg = (_("Driver initialize connection failed "
                         "(error: %(err)s).") % {'err': six.text_type(err)})
            LOG.exception(err_msg, resource=volume)

            self.driver.remove_export(context.elevated(), volume)

            raise exception.VolumeBackendAPIException(data=err_msg)

        conn_info = self._parse_connection_options(context, volume, conn_info)
        LOG.info("Initialize volume connection completed successfully.",
                 resource=volume)
        return conn_info
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def _parse_connection_options(self, context, volume, conn_info):
       # Add qos_specs to connection info
       typeid = volume.volume_type_id
       specs = None
       if typeid:
           res = volume_types.get_volume_type_qos_specs(typeid)
           qos = res['qos_specs']
           # only pass qos_specs that is designated to be consumed by
           # front-end, or both front-end and back-end.
           if qos and qos.get('consumer') in ['front-end', 'both']:
               specs = qos.get('specs')

           # NOTE(mnaser): The following configures for per-GB QoS
           if specs is not None:
               volume_size = int(volume.size)
               tune_opts = ('read_iops_sec', 'read_bytes_sec',
                            'write_iops_sec', 'write_bytes_sec',
                            'total_iops_sec', 'total_bytes_sec')

               for option in tune_opts:
                   option_per_gb = '%s_per_gb' % option
                   option_per_gb_min = '%s_per_gb_min' % option
                   option_max = '%s_max' % option
                   option_base = '%s_base' % option
                   if option_per_gb in specs:
                       minimum_value = int(specs.pop(option_per_gb_min, 0))
                       value = int(specs[option_per_gb]) * volume_size
                       per_gb_value = max(minimum_value, value)
                       base_value = int(specs.pop(option_base, 0))
                       final_value = base_value + per_gb_value
                       max_value = int(specs.pop(option_max, final_value))
                       specs[option] = min(final_value, max_value)
                       specs.pop(option_per_gb)

       qos_spec = dict(qos_specs=specs)
       conn_info['data'].update(qos_spec)
       ...............................................

connection info 返回给了nova，nova侧使用即可，至于attachment 只是数据库里面变更一下记录而已。