[PATCH] remove zone_mem_map

This patch removes zone_mem_map.

pfn_to_page uses pgdat, page_to_pfn uses zone.  page_to_pfn can use pgdat
instead of zone, which is only one user of zone_mem_map.  By modifing it,
we can remove zone_mem_map.

Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Dave Hansen <haveblue@us.ibm.com>
Cc: Christoph Lameter <christoph@lameter.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/include/asm-generic/memory_model.h b/include/asm-generic/memory_model.h
index a7bb497..0cfb086 100644
--- a/include/asm-generic/memory_model.h
+++ b/include/asm-generic/memory_model.h
@@ -45,11 +45,11 @@
 	NODE_DATA(__nid)->node_mem_map + arch_local_page_offset(__pfn, __nid);\
 })
 
-#define page_to_pfn(pg)			\
-({	struct page *__pg = (pg);		\
-	struct zone *__zone = page_zone(__pg);	\
-	(unsigned long)(__pg - __zone->zone_mem_map) +	\
-	 __zone->zone_start_pfn;			\
+#define page_to_pfn(pg)							\
+({	struct page *__pg = (pg);					\
+	struct pglist_data *__pgdat = NODE_DATA(page_to_nid(__pg));	\
+	(unsigned long)(__pg - __pgdat->node_mem_map) +			\
+	 __pgdat->node_start_pfn;					\
 })
 
 #elif defined(CONFIG_SPARSEMEM)