[PATCH] create memblk_online_map

From Matthew Dobson.

Create and use memblk_online_map.

This patch creates a memblk_online_map, much like cpu_online_map.  It
also creates the standard helper functions, ie: memblk_online(),
num_online_memblks(), memblk_set_online(), memblk_set_offline().

This is used by driverFS topology to keep track of which memory blocks
are in the system and online.

arch/i386/mach-generic/topology.c

@@ -48,7 +48,7 @@ static int __init topology_init(void)
 		arch_register_node(i);
 	for (i = 0; i < NR_CPUS; i++)
 		if (cpu_possible(i)) arch_register_cpu(i);
-	for (i = 0; i < numnodes; i++)
+	for (i = 0; i < num_online_memblks(); i++)
 		arch_register_memblk(i);
 	return 0;
 }

include/linux/mmzone.h

@@ -279,6 +279,38 @@ extern struct pglist_data contig_page_data;
 
 #endif /* !CONFIG_DISCONTIGMEM */
 
+
+extern DECLARE_BITMAP(memblk_online_map, MAX_NR_MEMBLKS);
+
+#if defined(CONFIG_DISCONTIGMEM) || defined(CONFIG_NUMA)
+
+#define memblk_online(memblk)		test_bit(memblk, memblk_online_map)
+#define memblk_set_online(memblk)	set_bit(memblk, memblk_online_map)
+#define memblk_set_offline(memblk)	clear_bit(memblk, memblk_online_map)
+static inline unsigned int num_online_memblks(void)
+{
+	int i, num = 0;
+
+	for(i = 0; i < MAX_NR_MEMBLKS; i++){
+		if (memblk_online(i))
+			num++;
+	}
+	return num;
+}
+
+#else /* !CONFIG_DISCONTIGMEM && !CONFIG_NUMA */
+
+#define memblk_online(memblk) \
+	({ BUG_ON((memblk) != 0); test_bit(memblk, memblk_online_map); })
+#define memblk_set_online(memblk) \
+	({ BUG_ON((memblk) != 0); set_bit(memblk, memblk_online_map); })
+#define memblk_set_offline(memblk) \
+	({ BUG_ON((memblk) != 0); clear_bit(memblk, memblk_online_map); })
+#define num_online_memblks()		1
+
+#endif /* CONFIG_DISCONTIGMEM || CONFIG_NUMA */
+
+
 #define MAP_ALIGN(x)	((((x) % sizeof(struct page)) == 0) ? (x) : ((x) + \
 		sizeof(struct page) - ((x) % sizeof(struct page))))
 

mm/page_alloc.c

@@ -29,6 +29,9 @@
 #include <linux/slab.h>
 #include <linux/notifier.h>
 
+#include <asm/topology.h>
+
+DECLARE_BITMAP(memblk_online_map, MAX_NR_MEMBLKS);
 struct pglist_data *pgdat_list;
 unsigned long totalram_pages;
 unsigned long totalhigh_pages;
@@ -1164,6 +1167,7 @@ void __init free_area_init_node(int nid, struct pglist_data *pgdat,
 	pgdat->node_mem_map = node_mem_map;
 
 	free_area_init_core(pgdat, zones_size, zholes_size);
+	memblk_set_online(__node_to_memblk(nid));
 
 	calculate_zone_bitmap(pgdat, zones_size);
 }