Enable POSIX file locking API

modulename: locks.ko

configname: CONFIG_FILE_LOCKING

Linux Kernel Configuration
└─>File systems
└─>Enable POSIX file locking API
In linux kernel since version 2.6.28 (release Date: 2008-12-24)  
This option enables standard file locking support, required
for filesystems like NFS and for the flock() system
call. Disabling this option saves about 11k.

source code:
is selected by
CONFIG_NFS_FS
CONFIG_NFSD