[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>

1 files changed, 6 insertions, 1 deletions

diff --git a/include/linux/mm.h b/include/linux/mm.h
index f2018775b995..856f0ee7e84a 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -499,12 +499,17 @@ static inline struct zone *page_zone(struct page *page)
         return zone_table[page_zone_id(page)];
 }
 
+static inline unsigned long zone_to_nid(struct zone *zone)
+{
+        return zone->zone_pgdat->node_id;
+}
+
 static inline unsigned long page_to_nid(struct page *page)
 {
         if (FLAGS_HAS_NODE)
                 return (page->flags >> NODES_PGSHIFT) & NODES_MASK;
         else
-                return page_zone(page)->zone_pgdat->node_id;
+                return zone_to_nid(page_zone(page));
 }
 static inline unsigned long page_to_section(struct page *page)
 {