A cluster filesystem.

Allows a cluster of computers to simultaneously use a block device
that is shared between them (with FC, iSCSI, NBD, etc...). GFS reads
and writes to the block device like a local filesystem, but also uses
a lock module to allow the computers coordinate their I/O so
filesystem consistency is maintained. One of the nifty features of
GFS is perfect consistency -- changes made to the filesystem on one
machine show up immediately on all other machines in the cluster.

To use the GFS2 filesystem in a cluster, you will need to enable
the locking module below. Documentation and utilities for GFS2 can
be found here: http://sources.redhat.com/cluster

The "nolock" lock module is now built in to GFS2 by default. If
you want to use the DLM, be sure to enable HOTPLUG and IPv4/6
networking.

source code:

fs/gfs2/