nfs: getcwd() returns ENOENT in subdirectory of mount

Issue

• While running a python multiprocessing test case, a failure occurs on 'os.cwd()', which results in an ENOENT, when calling getcwd() in a subdirectory of a NFS mount.

• With RPC debugging enabled, the following error is observed:

  nfs_revalidate_inode: (0:44/12583329) getattr failed, error=-512
  

• This issue is not observed on RHEL 7.