[PATCH] sparsemem: provide pfn_to_nid

Before SPARSEMEM is initialised we cannot provide an efficient pfn_to_nid()
implmentation; before initialisation is complete we use early_pfn_to_nid()
to provide location information.  Until recently there was no non-init user
of this functionality.  Provide a post init pfn_to_nid() implementation.

Note that this implmentation assumes that the pfn passed has been validated
with pfn_valid().  The current single user of this function already has
this check.
Signed-off-by: NAndy Whitcroft <apw@shadowen.org>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

include/linux/mmzone.h

@@ -596,7 +596,11 @@ static inline int pfn_valid(unsigned long pfn)
  * this restriction.
  */
 #ifdef CONFIG_NUMA
-#define pfn_to_nid		early_pfn_to_nid
+#define pfn_to_nid(pfn)							\
+({									\
+	unsigned long __pfn_to_nid_pfn = (pfn);				\
+	page_to_nid(pfn_to_page(__pfn_to_nid_pfn));			\
+})
 #else
 #define pfn_to_nid(pfn)		(0)
 #endif