maple_tree: add a test case to check maple_alloc

Add a test case to check whether the number of maple_alloc structures is
actually equal to mas->alloc->total.

Link: https://lkml.kernel.org/r/20230411041005.26205-2-zhangpeng.00@bytedance.com
Signed-off-by: Peng Zhang <zhangpeng.00@bytedance.com>
Cc: Liam R. Howlett <Liam.Howlett@Oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

tools/testing/radix-tree/maple.c

@@ -55,6 +55,28 @@ struct rcu_reader_struct {
 	struct rcu_test_struct2 *test;
 };
 
+static int get_alloc_node_count(struct ma_state *mas)
+{
+	int count = 1;
+	struct maple_alloc *node = mas->alloc;
+
+	if (!node || ((unsigned long)node & 0x1))
+		return 0;
+	while (node->node_count) {
+		count += node->node_count;
+		node = node->slot[0];
+	}
+	return count;
+}
+
+static void check_mas_alloc_node_count(struct ma_state *mas)
+{
+	mas_node_count_gfp(mas, MAPLE_ALLOC_SLOTS + 1, GFP_KERNEL);
+	mas_node_count_gfp(mas, MAPLE_ALLOC_SLOTS + 3, GFP_KERNEL);
+	MT_BUG_ON(mas->tree, get_alloc_node_count(mas) != mas->alloc->total);
+	mas_destroy(mas);
+}
+
 /*
  * check_new_node() - Check the creation of new nodes and error path
  * verification.
@@ -69,6 +91,8 @@ static noinline void check_new_node(struct maple_tree *mt)
 
 	MA_STATE(mas, mt, 0, 0);
 
+	check_mas_alloc_node_count(&mas);
+
 	/* Try allocating 3 nodes */
 	mtree_lock(mt);
 	mt_set_non_kernel(0);