GFS2: Merge lock_dlm module into GFS2

This is the big patch that I've been working on for some time
now. There are many reasons for wanting to make this change
such as:
 o Reducing overhead by eliminating duplicated fields between structures
 o Simplifcation of the code (reduces the code size by a fair bit)
 o The locking interface is now the DLM interface itself as proposed
   some time ago.
 o Fewer lookups of glocks when processing replies from the DLM
 o Fewer memory allocations/deallocations for each glock
 o Scope to do further optimisations in the future (but this patch is
   more than big enough for now!)

Please note that (a) this patch relates to the lock_dlm module and
not the DLM itself, that is still a separate module; and (b) that
we retain the ability to build GFS2 as a standalone single node
filesystem with out requiring the DLM.

This patch needs a lot of testing, hence my keeping it I restarted
my -git tree after the last merge window. That way, this has the maximum
exposure before its merged. This is (modulo a few minor bug fixes) the
same patch that I've been posting on and off the the last three months
and its passed a number of different tests so far.

Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

fs/gfs2/glops.c

@@ -12,7 +12,6 @@
 #include <linux/completion.h>
 #include <linux/buffer_head.h>
 #include <linux/gfs2_ondisk.h>
-#include <linux/lm_interface.h>
 #include <linux/bio.h>
 
 #include "gfs2.h"
@@ -390,18 +389,6 @@ static int trans_go_demote_ok(const struct gfs2_glock *gl)
 	return 0;
 }
 
-/**
- * quota_go_demote_ok - Check to see if it's ok to unlock a quota glock
- * @gl: the glock
- *
- * Returns: 1 if it's ok
- */
-
-static int quota_go_demote_ok(const struct gfs2_glock *gl)
-{
-	return !atomic_read(&gl->gl_lvb_count);
-}
-
 const struct gfs2_glock_operations gfs2_meta_glops = {
 	.go_xmote_th = meta_go_sync,
 	.go_type = LM_TYPE_META,
@@ -448,7 +435,6 @@ const struct gfs2_glock_operations gfs2_nondisk_glops = {
 };
 
 const struct gfs2_glock_operations gfs2_quota_glops = {
-	.go_demote_ok = quota_go_demote_ok,
 	.go_type = LM_TYPE_QUOTA,
 };