[nova] I would like to add another option for cross_az_attach

Hello all, In nova with setting [cinder]/ cross_az_attach option to false, nova creates instance and volume in same AZ. but some of usecase (in my case), we need to attach new volume in different AZ to the instance. so I need two options. one is for nova block device mapping and attaching volume and another is for attaching volume in specified AZ. [cinder] cross_az_attach = False enable_az_attach_list = AZ1,AZ2 how do you all think of it? Best, Kiseok