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, you will need to enable one or more of
the below locking modules. Documentation and utilities for GFS2 can
be found here: http://sources.redhat.com/cluster

source code:

fs/gfs2/