Can mount nfs dir, but unable to mount subdir?

Question

Have an odd issue where am able to mount a dir via NFS, but not able to mount any of that same dir's subdirs. Eg. On host server (CentOS Linux release 7.4.1708 (Core)), have dirs

[root@hwdatalake datalake]# pwd
/datalake

[root@hwdatalake datalake]# ls -lha .
total 8.0K
drwxrwx---. 14 root    etlusers     4.0K Dec 24 10:03 .
dr-xr-xr-x. 18 root    root          240 Dec 12 10:24 ..
dr-xr-x---.  2 root    root           29 Dec 16 11:08 CUPSS_HI
dr-xr-x---.  2 root    root           29 Dec 16 11:16 CUPSS_NAT
dr-xr-x---.  2 root    root           26 Dec 16 11:17 NAT_BRFSS

and have /etc/exports as

/datalake       airflowetl(rw,fsid=0,root_squash,sync)
/datalake/HI_BRFSS      airflowetl(ro,root_squash,sync)

On the client named airflowetl server (CentOS Linux release 7.4.1708 (Core)), am able to successfully mount the toplevel dir from the nfs server...

[root@airflowetl airflow]# mount -v hwdatalake.co.local:/datalake /dlnfs
mount.nfs: timeout set for Mon Dec 30 13:04:59 2019
mount.nfs: trying text-based options 'vers=4.1,addr=172.18.4.97,clientaddr=172.18.4.69'=

but also see

[root@airflowetl airflow]# umount /dlnfs
[root@airflowetl airflow]# showmount -e hwdatalake
clnt_create: RPC: Port mapper failure - Unable to receive: errno 113 (No route to host)

and when trying to mount the subdir instead, we see

[root@airflowetl airflow]# mount -v hwdatalake.co.local:/datalake/HI_BRFSS /dlnfs
mount.nfs: timeout set for Mon Dec 30 13:12:55 2019
mount.nfs: trying text-based options 'vers=4.1,addr=172.18.4.97,clientaddr=172.18.4.69'
mount.nfs: mount(2): Permission denied
mount.nfs: trying text-based options 'vers=4.0,addr=172.18.4.97,clientaddr=172.18.4.69'
mount.nfs: mount(2): Permission denied
mount.nfs: trying text-based options 'addr=172.18.4.97'
mount.nfs: prog 100003, trying vers=3, prot=6
mount.nfs: portmap query failed: RPC: Remote system error - No route to host
mount.nfs: trying text-based options 'vers=4.0,addr=172.18.4.97,clientaddr=172.18.4.69'

Yet the previous dir was able to be mounted and already have firewall setting ostensibly configured...

firewall-cmd --permanent --zone=public --add-service=ssh
firewall-cmd --permanent --zone=public --add-service=nfs
firewall-cmd --reload

Not really sure what to make of this. Anyone with more experience have any further debugging tips or know what's going wrong here?

Answer 1

After some searching, based on

showmount -e hwdatalake
RPC: Remote system errorRPC: Port mapper failure - RPC: Timed out.

did...

firewall-cmd --permanent --zone=public --add-service=mountd
firewall-cmd --permanent --zone=public --add-service=rpc-bind
firewall-cmd --reload

to check that the rpc service was not getting caught in the firewall, which fixed both the problem with showmount and being able to mount the lower level dirs.

Used this article (was previously using similar article here that omitted these steps)