[PATCH] NUMA: Add zone_to_nid function

There are many places where we need to determine the node of a zone.
Currently we use a difficult to read sequence of pointer dereferencing.
Put that into an inline function and use throughout VM.  Maybe we can find
a way to optimize the lookup in the future.

Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/arch/i386/mm/discontig.c b/arch/i386/mm/discontig.c
index 07c300f..fb5d8b7 100644
--- a/arch/i386/mm/discontig.c
+++ b/arch/i386/mm/discontig.c
@@ -422,7 +422,7 @@
 		zone_end_pfn = zone_start_pfn + zone->spanned_pages;
 
 		printk("Initializing %s for node %d (%08lx:%08lx)\n",
-				zone->name, zone->zone_pgdat->node_id,
+				zone->name, zone_to_nid(zone),
 				zone_start_pfn, zone_end_pfn);
 
 		for (node_pfn = zone_start_pfn; node_pfn < zone_end_pfn; node_pfn++) {