numa: Generalize numa_map_to_online_node()

The function in fact searches the nearest node for a given one,
based on a N_ONLINE state. This is a common pattern to search
for a nearest node.

This patch converts numa_map_to_online_node() to numa_nearest_node()
so that others won't need to opencode the logic.
Signed-off-by: Yury Norov <yury.norov@gmail.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Mel Gorman <mgorman@suse.de>
Link: https://lore.kernel.org/r/20230819141239.287290-2-yury.norov@gmail.com

include/linux/numa.h

@@ -25,7 +25,7 @@
 #include <asm/sparsemem.h>
 
 /* Generic implementation available */
-int numa_map_to_online_node(int node);
+int numa_nearest_node(int node, unsigned int state);
 
 #ifndef memory_add_physaddr_to_nid
 static inline int memory_add_physaddr_to_nid(u64 start)
@@ -44,10 +44,11 @@ static inline int phys_to_target_node(u64 start)
 }
 #endif
 #else /* !CONFIG_NUMA */
-static inline int numa_map_to_online_node(int node)
+static inline int numa_nearest_node(int node, unsigned int state)
 {
 	return NUMA_NO_NODE;
 }
+
 static inline int memory_add_physaddr_to_nid(u64 start)
 {
 	return 0;
@@ -58,6 +59,8 @@ static inline int phys_to_target_node(u64 start)
 }
 #endif
 
+#define numa_map_to_online_node(node) numa_nearest_node(node, N_ONLINE)
+
 #ifdef CONFIG_HAVE_ARCH_NODE_DEV_GROUP
 extern const struct attribute_group arch_node_dev_group;
 #endif

mm/mempolicy.c

@@ -131,22 +131,26 @@ static struct mempolicy default_policy = {
 static struct mempolicy preferred_node_policy[MAX_NUMNODES];
 
 /**
- * numa_map_to_online_node - Find closest online node
+ * numa_nearest_node - Find nearest node by state
  * @node: Node id to start the search
+ * @state: State to filter the search
  *
- * Lookup the next closest node by distance if @nid is not online.
+ * Lookup the closest node by distance if @nid is not in state.
  *
- * Return: this @node if it is online, otherwise the closest node by distance
+ * Return: this @node if it is in state, otherwise the closest node by distance
  */
-int numa_map_to_online_node(int node)
+int numa_nearest_node(int node, unsigned int state)
 {
 	int min_dist = INT_MAX, dist, n, min_node;
 
-	if (node == NUMA_NO_NODE || node_online(node))
+	if (state >= NR_NODE_STATES)
+		return -EINVAL;
+
+	if (node == NUMA_NO_NODE || node_state(node, state))
 		return node;
 
 	min_node = node;
-	for_each_online_node(n) {
+	for_each_node_state(n, state) {
 		dist = node_distance(node, n);
 		if (dist < min_dist) {
 			min_dist = dist;
@@ -156,7 +160,7 @@ int numa_map_to_online_node(int node)
 
 	return min_node;
 }
-EXPORT_SYMBOL_GPL(numa_map_to_online_node);
+EXPORT_SYMBOL_GPL(numa_nearest_node);
 
 struct mempolicy *get_task_policy(struct task_struct *p)
 {