PowerScale OneFS: Unable to mount NFSv4 using FQDN with error "Operation not permitted"

An NFS client authenticated with Kerberos and possessing a valid GSS ticket tries to mount an export using an alias but encounters a failure.

# mount -t nfs4 fullyqualifieddomain:/aliases01  /mnt/test -vvvv
mount.nfs4: timeout set for Wed Apr 10 12:14:37 2024
mount.nfs4: trying text-based options 'vers=4.2,addr=x.x.x.x,clientaddr=x.x.x.x'
mount.nfs4: mount(2): Operation not permitted
mount.nfs4: trying text-based options 'vers=4,minorversion=1,addr=x.x.x.x,clientaddr=x.x.x.x'
mount.nfs4: mount(2): Operation not permitted
mount.nfs4: trying text-based options 'vers=4,addr=x.x.x.x,clientaddr=x.x.x.x'
mount.nfs4: mount(2): Operation not permitted
mount.nfs4: Operation not permitted

In packet captures, you see OneFS replies with no values to the SECINFO call:

Network File System
    [Program Version: 4]
    [V4 Procedure: COMPOUND (1)]
    GSS Data, Ops(2): PUTFH SECINFO
        Length: 36
        GSS Sequence Number: 3
        Status: NFS4_OK (0)
        Tag: <EMPTY>
            length: 0
            contents: <EMPTY>
        Operations (count: 2)
            Opcode: PUTFH (22)
                Status: NFS4_OK (0)
            Opcode: SECINFO (33)
                Status: NFS4_OK (0)
                Flavors Info
                    no values <<<<<<<<<<<<<<<<<<<<<<<<
        [Main Opcode: SECINFO (33)]

Usually, SECINFO provides selectable flavor values for valid FH (file handle) access during mount.

   The new SECINFO operation allows the client to determine, on a
   per filehandle basis, what security triple is to be used for server
   access.

However, due to a code defect, the client cannot obtain its real target over preliminary compound with the ROOTFH. As a result, OneFS replies with no flavors, and the session is destroyed.

Workarounds while a code fix is worked:

1. Specify RPC authentication flavor at the time of mount, for example: sec=sys
2. Use the full mount path vs. alias

Acronyms used in this KB:
NFS - Network File System

Generic Security Service (GSS) -- A framework for providing security services in a networked environment. It includes authentication, integrity, and confidentiality services.

Remote Procedure Call (RPC) is a communication protocol used in distributed computing.