Migrating lustre from 2.9.x to 2.10.x: Network setup

If you upgrade the Lustre 2.9.0 to 2.10, the service lnet will fail due to the miss-configured /etc/lnet.conf  which is comming with the lustre-2.10.0-1.el7.x86_64 server package.
In 2.9 usually the line "options lnet networks=o2ib(ib0),o2ib3(ib0)" in the /etc/modprobe.d/lnt.conf brings the network up for the lnet but for the 2.10 it is simply ignored. It is due to the new network management in 2.10.x and above.
Digging littlebit more looks like a daemon unable to load /etc/lnet.conf .

The temporal solution what I found is manually setting the lnet network:

lnetctl net add --net o2ib --if ib0

Then dump Yaml file of the working configuration and restart the lnet:

lnetctl net show --verbose >/etc/lnet.conf
service lnet stop
service lnet start