Following the steps from Comment 8 ,
Deployed a ceph 3.1 cluster with nfs role on a dedicated node,it worked fine,Moving to to verified state.
version: ceph-ansible 3.1.0-0.1.rc17.el7cp,ceph 12.2.5-39.el7cp.x86_64
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.
For information on the advisory, and where to find the updated
files, follow the link below.
If the solution does not work for you, open a new bug report.
https://access.redhat.com/errata/RHBA-2018:2819