1、mania/share/manager.py 2144行，调用delete_share_instance删除share instance

    def delete_share_instance(self, context, share_instance_id, force=False):
        """Delete a share instance."""
        context = context.elevated()
        share_instance = self._get_share_instance(context, share_instance_id)
        share_server = self._get_share_server(context, share_instance)

        try:
            self.access_helper.update_access_rules(
                context,
                share_instance_id,
                delete_rules="all",
                share_server=share_server
            )
        except exception.ShareResourceNotFound:
            LOG.warning(_LW("Share instance %s does not exist in the "
                            "backend."), share_instance_id)
        except Exception:
            with excutils.save_and_reraise_exception() as exc_context:
                if force:
                    msg = _LE("The driver was unable to delete access rules "
                              "for the instance: %s. Will attempt to delete "
                              "the instance anyway.")
                    LOG.error(msg, share_instance_id)
                    exc_context.reraise = False
                else:
                    self.db.share_instance_update(
                        context,
                        share_instance_id,
                        {'status': constants.STATUS_ERROR_DELETING})

        try:
            self.driver.delete_share(context, share_instance,
                                     share_server=share_server)
        except exception.ShareResourceNotFound:
            LOG.warning(_LW("Share instance %s does not exist in the "
                            "backend."), share_instance_id)
        except Exception:
            with excutils.save_and_reraise_exception() as exc_context:
                if force:
                    msg = _LE("The driver was unable to delete the share "
                              "instance: %s on the backend. Since this "
                              "operation is forced, the instance will be "
                              "deleted from Manila's database. A cleanup on "
                              "the backend may be necessary.")
                    LOG.error(msg, share_instance_id)
                    exc_context.reraise = False
                else:
                    self.db.share_instance_update(
                        context,
                        share_instance_id,
                        {'status': constants.STATUS_ERROR_DELETING})

        self.db.share_instance_delete(context, share_instance_id)
        LOG.info(_LI("Share instance %s: deleted successfully."),
                 share_instance_id)

        self._check_delete_share_server(context, share_instance)

2、在2175行，有如下方法

self.driver.delete_share(context, share_instance,
             share_server=share_server)

3、self.driver.delete_share调用mania/share/drivers/generic.py中的delete_share

    def delete_share(self, context, share, share_server=None):
        """Deletes share."""
        helper = self._get_helper(share)
        if not self.driver_handles_share_servers:
            share_server = self.service_instance_manager.get_common_server()
        if self._is_share_server_active(context, share_server):
            helper.remove_export(
                share_server['backend_details'], share['name'])
            self._unmount_device(share, share_server['backend_details'])
            self._detach_volume(self.admin_context, share,
                                share_server['backend_details'])
        # Note(jun): It is an intended breakage to deal with the cases
        # with any reason that caused absence of Nova instances.
        self._deallocate_container(self.admin_context, share)
        self.private_storage.delete(share['id'])

4、generic.py中的delete_share执行如下操作:

  1. remove_export:移除所有nfs export，remove_export位于mania/share/drivers/helpers.py156行，remove_export没有做实际操作，remove_export实际由manager.py中delete_share_instance方法2151行，self.access_helper.update_access_rules完成

  2. 卸载volume文件系统:self._umount_device

  3. 卸载cinder volume:self._detach_volume

  4. 删除cinder volume，保留nova instance，如果有新的share instance 创建，会将保留的nova instance用于提供share instance

5、manager.py中delete_share_instance方法2151行，self.access_helper.update_access_rules 调用，mania/share/access.py中的update_access_rules

    def update_access_rules(self, context, share_instance_id, add_rules=None,
                            delete_rules=None, share_server=None):
        """Update access rules in driver and database for given share instance.

        :param context: current context
        :param share_instance_id: Id of the share instance model
        :param add_rules: list with ShareAccessMapping models or None - rules
        which should be added
        :param delete_rules: list with ShareAccessMapping models, "all", None
        - rules which should be deleted. If "all" is provided - all rules will
        be deleted.
        :param share_server: Share server model or None
        """
        share_instance = self.db.share_instance_get(
            context, share_instance_id, with_share_data=True)
        share_id = share_instance["share_id"]

        @utils.synchronized(
            "update_access_rules_for_share_%s" % share_id, external=True)
        def _update_access_rules_locked(*args, **kwargs):
            return self._update_access_rules(*args, **kwargs)

        _update_access_rules_locked(
            context=context,
            share_instance_id=share_instance_id,
            add_rules=add_rules,
            delete_rules=delete_rules,
            share_server=share_server,
        )

6、update_access_rules通过self._update_access_rules方法，调用self.driver.update_access完成access的删除

7、self.driver.update_access即generic.py中的upate_access，genery.py update_access调用mania/share/drivers/helpers.py中class NFSHelper的upate_access方法完成access的删除

delete_share_instance(manager.py)------>update_access_rules(access.py)
                          |                     |
                          |                     |
                          |                     |
                          |                     ------>upate_access(generic.py)
                          |                     |
                          |                     |
                          |                     |
                          |                     ------>update_access(helpers.py,NFSHelper)
                          |
                          |
                          | 
                          |
                          ------>delete_share(generic.py)