GFS2 DLM locking

configname: CONFIG_GFS2_FS_LOCKING_DLM

Linux Kernel Configuration
└─>File systems
└─>GFS2 DLM locking
In linux kernel since version 2.6.20 (release Date: 2007-02-04)  
Multiple node locking module for GFS2

Most users of GFS2 will require this. It provides the locking
interface between GFS2 and the DLM, which is required to use GFS2
in a cluster environment.