At unmount time, we would generally like to explicitly unlock as few
glocks as possible for efficiency.  We are already skipping glocks that
don't have a lock value block (LVB), but we can also skip glocks which
are not held in DLM_LOCK_EX or DLM_LOCK_PW mode (of which gfs2 only uses
DLM_LOCK_EX under the name LM_ST_EXCLUSIVE).
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Cc: David Teigland <teigland@redhat.com>