cinder侧卸载卷分析，存储类型以lvm+iscsi的方式为分析基础
在虚机卸载卷的过程中，主要涉及如下三个函数
1)cinder.volume.api.begin_detaching 把volume的状态改为detaching，阻止其它节点执行挂载操作
2)cinder.volume.api.terminate_connection 进行target,lun等信息的清理
3)cinder.volume.api.detach 更新cinder数据库，设置卷的状态为available
1、nova侧调用cinderclient的begin_detaching方法，
nova/compute/api.py:API def _check_and_begin_detach(self, context, volume, instance): self.volume_api.check_detach(context, volume, instance=instance) self.volume_api.begin_detaching(context, volume['id'])
1)cinderclient端接受到nova发送的begin_detaching操作的http请求，其入口处理函数为
cinder/api/contrib/volume_actions.py:VolumeActionsController def _begin_detaching(self, req, id, body): """Update volume status to 'detaching'.""" context = req.environ['cinder.context'] # Not found exception will be handled at the wsgi level volume = self.volume_api.get(context, id) self.volume_api.begin_detaching(context, volume) return webob.Response(status_int=http_client.ACCEPTED) 该函数的主要作用是通过volume 的uuid，获取volume实例信息，并调用volume目录下的api模块
2)进一步调用cinder volume的api模块的begin_detaching函数，进行数据库的操作，更新卷的状态为detaching,防止其他api对这个卷操作
@wrap_check_policy def begin_detaching(self, context, volume): # If we are in the middle of a volume migration, we don't want the # user to see that the volume is 'detaching'. Having # 'migration_status' set will have the same effect internally. expected = {'status': 'in-use', 'attach_status': fields.VolumeAttachStatus.ATTACHED, 'migration_status': self.AVAILABLE_MIGRATION_STATUS} result = volume.conditional_update({'status': 'detaching'}, expected) if not (result or self._is_volume_migrating(volume)): msg = _("Unable to detach volume. Volume status must be 'in-use' " "and attach_status must be 'attached' to detach.") LOG.error(msg) raise exception.InvalidVolume(reason=msg) LOG.info(_LI("Begin detaching volume completed successfully."), resource=volume)
2、nova侧向cinder发送terminate_connection请求，请求删除卷的连接信息
def _detach_volume(self, context, volume_id, instance, destroy_bdm=True,attachment_id=None):
......
self.volume_api.terminate_connection(context, volume_id, connector)
......
self.volume_api.detach(context.elevated(), volume_id, instance.uuid,attachment_id)
1)cinderclient接受nova发送过来的os-terminate_connection请求
@wsgi.action('os-terminate_connection') def _terminate_connection(self, req, id, body): """Terminate volume attachment.""" context = req.environ['cinder.context'] # Not found exception will be handled at the wsgi level volume = self.volume_api.get(context, id) try: connector = body['os-terminate_connection']['connector'] except KeyError: raise webob.exc.HTTPBadRequest( explanation=_("Must specify 'connector'")) try: self.volume_api.terminate_connection(context, volume, connector) except exception.VolumeBackendAPIException: msg = _("Unable to terminate volume connection from backend.") raise webob.exc.HTTPInternalServerError(explanation=msg) return webob.Response(status_int=http_client.ACCEPTED)
2)进一步调用volume目录下api模块的 terminate_connection 函数,对该请求进行处理
cinder/volume/api.py:API类 @wrap_check_policy def terminate_connection(self, context, volume, connector, force=False): step 1: self.volume_rpcapi.terminate_connection(context,volume,connector,force) step 2 :self.unreserve_volume(context, volume)
step 1:cinder api进一步发送RPC请求给volume所在的cinder-volume服务节点，最终在cinder-volume节点，
由cinder/volume/manager.py:VolumeManager的terminate_connection处理，该函数的处理，主要包括如下内容
def terminate_connection(self, context, volume_id, connector, force=False): utils.require_driver_initialized(self.driver)----获取对应的驱动信息 volume_ref = self.db.volume_get(context, volume_id)-----从数据库中获取卷的信息 try: step 1.1 self.driver.terminate_connection(volume_ref, connector, force=force)-----调用对应的驱动的terminate_connection函数
step 1.1 :
使用lvm+lio的方式，代码跳转过程如下：drivers/lvm.py -> targets/lio.py，从target 的acl中删除initiator，从而有效的在 target侧关闭iscis session连接
def terminate_connection(self, volume, connector, **kwargs): volume_iqn = volume['provider_location'].split(' ')[1] # Delete initiator iqns from target ACL try: self._execute('cinder-rtstool', 'delete-initiator', volume_iqn, connector['initiator'], run_as_root=True) except putils.ProcessExecutionError: LOG.exception( _LE("Failed to delete initiator iqn %s from target."), connector['initiator']) raise exception.ISCSITargetDetachFailed(volume_id=volume['id']) # We make changes persistent self._persist_configuration(volume['id'])
3、nova给cinderclient发送os-detach命令，更改cinder数据库
1)cinder侧接受nova更新cinder数据库的入口函数
cinder/api/contrib/volume_actions.py @wsgi.action('os-detach') def _detach(self, req, id, body): volume = self.volume_api.get(context, id) attachment_id = None if body['os-detach']: attachment_id = body['os-detach'].get('attachment_id', None) try: self.volume_api.detach(context, volume, attachment_id)
2)最后cinder-api通过RPC请求到cinder-volume节点，调用remove_export,移除target信息，更新数据库，把volume状态改为available，attach_status状态为detached
cindervolumeapi.py @wrap_check_policy def detach(self, context, volume, attachment_id): if volume['status'] == 'maintenance': LOG.info(_LI('Unable to detach volume, ' 'because it is in maintenance.'), resource=volume) msg = _("The volume cannot be detached in maintenance mode.") raise exception.InvalidVolume(reason=msg) detach_results = self.volume_rpcapi.detach_volume(context, volume, attachment_id) LOG.info(_LI("Detach volume completed successfully."), resource=volume) return detach_results
最终调用cinder-volume服务的manage.py文件中的detach_volume接口
@coordination.synchronized('{volume_id}-{f_name}') def detach_volume(self, context, volume_id, attachment_id=None, volume=None): """Updates db to show volume is detached.""" # TODO(vish): refactor this into a more general "unreserve" # FIXME(lixiaoy1): Remove this in v4.0 of RPC API. if volume is None: # For older clients, mimic the old behavior and look up the volume # by its volume_id. volume = objects.Volume.get_by_id(context, volume_id) if attachment_id: try: attachment = objects.VolumeAttachment.get_by_id(context, attachment_id) except exception.VolumeAttachmentNotFound: LOG.info(_LI("Volume detach called, but volume not attached."), resource=volume) # We need to make sure the volume status is set to the correct # status. It could be in detaching status now, and we don't # want to leave it there. volume.finish_detach(attachment_id) return else: # We can try and degrade gracefully here by trying to detach # a volume without the attachment_id here if the volume only has # one attachment. This is for backwards compatibility. attachments = volume.volume_attachment if len(attachments) > 1: # There are more than 1 attachments for this volume # we have to have an attachment id. msg = _("Detach volume failed: More than one attachment, " "but no attachment_id provided.") LOG.error(msg, resource=volume) raise exception.InvalidVolume(reason=msg) elif len(attachments) == 1: attachment = attachments[0] else: # there aren't any attachments for this volume. # so set the status to available and move on. LOG.info(_LI("Volume detach called, but volume not attached."), resource=volume) volume.status = 'available' volume.attach_status = fields.VolumeAttachStatus.DETACHED volume.save() return self._notify_about_volume_usage(context, volume, "detach.start") try: # NOTE(flaper87): Verify the driver is enabled # before going forward. The exception will be caught # and the volume status updated. utils.require_driver_initialized(self.driver) LOG.info(_LI('Detaching volume %(volume_id)s from instance ' '%(instance)s.'), {'volume_id': volume_id, 'instance': attachment.get('instance_uuid')}, resource=volume) self.driver.detach_volume(context, volume, attachment) except Exception as ex: with excutils.save_and_reraise_exception(): self.db.volume_attachment_update( context, attachment.get('id'), { 'attach_status': fields.VolumeAttachStatus.ERROR_DETACHING}) self.db.volume_metadata_update(context, volume_id, {'error': six.text_type(ex)}, False) # NOTE(jdg): We used to do an ensure export here to # catch upgrades while volumes were attached (E->F) # this was necessary to convert in-use volumes from # int ID's to UUID's. Don't need this any longer # We're going to remove the export here # (delete the iscsi target) try: utils.require_driver_initialized(self.driver) self.driver.remove_export(context.elevated(), volume) except exception.DriverNotInitialized: with excutils.save_and_reraise_exception(): LOG.exception(_LE("Detach volume failed, due to " "uninitialized driver."), resource=volume) except Exception as ex: LOG.exception(_LE("Detach volume failed, due to " "remove-export failure."), resource=volume) raise exception.RemoveExportException(volume=volume_id, reason=six.text_type(ex)) volume.finish_detach(attachment.id) self._notify_about_volume_usage(context, volume, "detach.end") LOG.info(_LI("Detach volume completed successfully."), resource=volume)