[PATCH 3/3] vmalloc: Use for_each_vmap_node() in purge-vmap-area

["Uladzislau Rezki (Sony)" <urezki@gmail.com>]

Update a __purge_vmap_area_lazy() to use introduced helper.
This is last place in vmalloc code. Also this patch introduces
an extra function which is node_to_id() that converts a vmap_node
pointer to an index in array.

__purge_vmap_area_lazy() requires that extra function.

Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
---
 mm/vmalloc.c | 19 +++++++++++++++----
 1 file changed, 15 insertions(+), 4 deletions(-)

diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 3ff9acd64c077..409b8f372647f 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -923,6 +923,19 @@ id_to_node(unsigned int id)
 	return &vmap_nodes[id % nr_vmap_nodes];
 }
 
+static inline unsigned int
+node_to_id(struct vmap_node *node)
+{
+	/* Pointer arithmetic. */
+	unsigned int id = node - vmap_nodes;
+
+	if (likely(id < nr_vmap_nodes))
+		return id;
+
+	WARN_ONCE(1, "An address 0x%p is out-of-bounds.\n", node);
+	return 0;
+}
+
 /*
  * We use the value 0 to represent "no node", that is why
  * an encoded value will be the node-id incremented by 1.
@@ -2259,9 +2272,7 @@ static bool __purge_vmap_area_lazy(unsigned long start, unsigned long end,
 	 */
 	purge_nodes = CPU_MASK_NONE;
 
-	for (i = 0; i < nr_vmap_nodes; i++) {
-		vn = &vmap_nodes[i];
-
+	for_each_vmap_node(vn) {
 		INIT_LIST_HEAD(&vn->purge_list);
 		vn->skip_populate = full_pool_decay;
 		decay_va_pool_node(vn, full_pool_decay);
@@ -2280,7 +2291,7 @@ static bool __purge_vmap_area_lazy(unsigned long start, unsigned long end,
 		end = max(end, list_last_entry(&vn->purge_list,
 			struct vmap_area, list)->va_end);
 
-		cpumask_set_cpu(i, &purge_nodes);
+		cpumask_set_cpu(node_to_id(vn), &purge_nodes);
 	}
 
 	nr_purge_nodes = cpumask_weight(&purge_nodes);
-- 
2.39.5