It should not be /tmp/.hdfs-nfs, which is by default used by NFS gateway as a temporary file dump area. Currently the NFS gateway shares only one export “/” (can be configured to a different sub-directory).
The client could mount the export at any local directory.
For the error you have got, it’s because the port is already used. You can check if the portmap/rpcbind or nfsd already running on the machine by doing “rpcinfo -p localhost”.
Thanks,
Brandon