[PATCH] Replace highest_possible_node_id() with nr_node_ids

highest_possible_node_id() is currently used to calculate the last possible
node idso that the network subsystem can figure out how to size per node
arrays.

I think having the ability to determine the maximum amount of nodes in a
system at runtime is useful but then we should name this entry
correspondingly, it should return the number of node_ids, and the the value
needs to be setup only once on bootup.  The node_possible_map does not
change after bootup.

This patch introduces nr_node_ids and replaces the use of
highest_possible_node_id().  nr_node_ids is calculated on bootup when the
page allocators pagesets are initialized.

[deweerdt@free.fr: fix oops]
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Cc: Neil Brown <neilb@suse.de>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Signed-off-by: Frederik Deweerdt <frederik.deweerdt@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/nodemask.h

@@ -352,7 +352,7 @@ extern nodemask_t node_possible_map;
 #define node_possible(node)	node_isset((node), node_possible_map)
 #define first_online_node	first_node(node_online_map)
 #define next_online_node(nid)	next_node((nid), node_online_map)
-int highest_possible_node_id(void);
+extern int nr_node_ids;
 #else
 #define num_online_nodes()	1
 #define num_possible_nodes()	1
@@ -360,7 +360,7 @@ int highest_possible_node_id(void);
 #define node_possible(node)	((node) == 0)
 #define first_online_node	0
 #define next_online_node(nid)	(MAX_NUMNODES)
-#define highest_possible_node_id()	0
+#define nr_node_ids		1
 #endif
 
 #define any_online_node(mask)			\

mm/page_alloc.c

@@ -664,6 +664,26 @@ static int rmqueue_bulk(struct zone *zone, unsigned int order,
 	return i;
 }
 
+#if MAX_NUMNODES > 1
+int nr_node_ids __read_mostly;
+EXPORT_SYMBOL(nr_node_ids);
+
+/*
+ * Figure out the number of possible node ids.
+ */
+static void __init setup_nr_node_ids(void)
+{
+	unsigned int node;
+	unsigned int highest = 0;
+
+	for_each_node_mask(node, node_possible_map)
+		highest = node;
+	nr_node_ids = highest + 1;
+}
+#else
+static void __init setup_nr_node_ids(void) {}
+#endif
+
 #ifdef CONFIG_NUMA
 /*
  * Called from the slab reaper to drain pagesets on a particular node that
@@ -3169,6 +3189,7 @@ static int __init init_per_zone_pages_min(void)
 		min_free_kbytes = 65536;
 	setup_per_zone_pages_min();
 	setup_per_zone_lowmem_reserve();
+	setup_nr_node_ids();
 	return 0;
 }
 module_init(init_per_zone_pages_min)
@@ -3370,18 +3391,4 @@ EXPORT_SYMBOL(pfn_to_page);
 EXPORT_SYMBOL(page_to_pfn);
 #endif /* CONFIG_OUT_OF_LINE_PFN_TO_PAGE */
 
-#if MAX_NUMNODES > 1
-/*
- * Find the highest possible node id.
- */
-int highest_possible_node_id(void)
-{
-	unsigned int node;
-	unsigned int highest = 0;
 
-	for_each_node_mask(node, node_possible_map)
-		highest = node;
-	return highest;
-}
-EXPORT_SYMBOL(highest_possible_node_id);
-#endif

net/sunrpc/svc.c

@@ -115,7 +115,7 @@ fail:
 static int
 svc_pool_map_init_percpu(struct svc_pool_map *m)
 {
-	unsigned int maxpools = highest_possible_processor_id()+1;
+	unsigned int maxpools = highest_possible_processor_id() + 1;
 	unsigned int pidx = 0;
 	unsigned int cpu;
 	int err;
@@ -143,7 +143,7 @@ svc_pool_map_init_percpu(struct svc_pool_map *m)
 static int
 svc_pool_map_init_pernode(struct svc_pool_map *m)
 {
-	unsigned int maxpools = highest_possible_node_id()+1;
+	unsigned int maxpools = nr_node_ids;
 	unsigned int pidx = 0;
 	unsigned int node;
 	int err;