Ocfs2 devel - Jan 2010 - [PATCH 0/3] ocfs2: add freeze/thaw support

limitations:
1) only the THAW from the node from which FREEZE is issued takes effect.
those from other nodes are ignored.

2) a nested cross cluster FREEZE is not supported. that means if a FREEZE
is requested when the cluster is in frozen state(frozen from node A in
the cluster) from a node other than node A, the request its self can
succeed but it can't ensure ocfs2 volume consistency.

the following 3 patches are based on tiger's patch for freeze/thaw.
since there are lots of differences, please review carefully ;)