There is no standard way to collect file system inode usage via SNMP. However, it can be easily achieved by adding the following line to the snmpd.conf file on any system using the Net SNMP agent (which is most Linux systems, current Solaris, etc) and restarting the snmp daemon.
extend lm-inodes /bin/df -ilTP -x tmpfs
After snmpd is restarted with the above line, run Active Discovery on the host in LogicMonitor. The datasource Linux Disk Inodes- should then discover all file systems, and monitor them for inode usage, alerting when inodes are becoming low. (You may need to import this datasource from the LogicMonitor core repository.)