ocfs2: use the new DLM operation callbacks while requesting new lockspace

ocfs2: use the new DLM operation callbacks while requesting new lockspace

Attempt to use the new DLM operations.  If it is not supported, use the
traditional ocfs2_controld.

To exchange ocfs2 versioning, we use the LVB of the version dlm lock.  It
first attempts to take the lock in EX mode (non-blocking).  If successful
(which means it is the first mount), it writes the version number and
downconverts to PR lock.  If it is unsuccessful, it reads the version from
the lock.

If this becomes the standard (with o2cb as well), it could simplify
userspace tools to check if the filesystem is mounted on other nodes.

Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Mark Fasheh <mfasheh@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>