Motivation:
according to rfc 7862 minimal nfs v4.2 server should accept minorversion
2 requests and can respond 'not supported' to all in the spec defined
operations.

Modification:
accept minorversion 2 and respond 'not supported' to

- ALLOCATE
- COPY
- COPY_NOTIFY
- DEALLOCATE
- IO_ADVISE
- OFFLOAD_CANCEL
- OFFLOAD_STATUS
- READ_PLUS
- SEEK
- WRITE_SAME
- CLONE

Result:

'Noop' spec compliant nfs 4.2 implementation

Acked-by: Lea Morschel
Target: master