bootmem: Move contig_page_data definition to bootmem.c/nobootmem.c

Now that bootmem.c and nobootmem.c are separate, it's cleaner to
define contig_page_data in each file than in page_alloc.c with #ifdef.
Move it.

This patch doesn't introduce any behavior change.

-v2: According to Andrew, fixed the struct layout.
-tj: Updated commit description.
Signed-off-by: NYinghai Lu <yinghai@kernel.org>
Acked-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NTejun Heo <tj@kernel.org>

mm/bootmem.c

@@ -23,6 +23,13 @@
 
 #include "internal.h"
 
+#ifndef CONFIG_NEED_MULTIPLE_NODES
+struct pglist_data __refdata contig_page_data = {
+	.bdata = &bootmem_node_data[0]
+};
+EXPORT_SYMBOL(contig_page_data);
+#endif
+
 unsigned long max_low_pfn;
 unsigned long min_low_pfn;
 unsigned long max_pfn;

mm/nobootmem.c

@@ -23,6 +23,11 @@
 
 #include "internal.h"
 
+#ifndef CONFIG_NEED_MULTIPLE_NODES
+struct pglist_data __refdata contig_page_data;
+EXPORT_SYMBOL(contig_page_data);
+#endif
+
 unsigned long max_low_pfn;
 unsigned long min_low_pfn;
 unsigned long max_pfn;

mm/page_alloc.c

@@ -4841,15 +4841,6 @@ void __init set_dma_reserve(unsigned long new_dma_reserve)
 	dma_reserve = new_dma_reserve;
 }
 
-#ifndef CONFIG_NEED_MULTIPLE_NODES
-struct pglist_data __refdata contig_page_data = {
-#ifndef CONFIG_NO_BOOTMEM
- .bdata = &bootmem_node_data[0]
-#endif
- };
-EXPORT_SYMBOL(contig_page_data);
-#endif
-
 void __init free_area_init(unsigned long *zones_size)
 {
 	free_area_init_node(0, zones_size,