Apologies for the delayed response. We currently do not have the documentation for the minimum required permissions for Cinder to work with 7-mode. You do need to ensure that volumes corresponding to exports have read/write permissions set on the Data ONTAP controllers. You can also find more information on other available parameters that affect the behavior of NetApp's NFS driver HERE.
Kindly let us know if you're running into a specific problem during the configuration process, and we'll try to help you sort it out.