maple_tree: add regression test for spanning store bug

	check_nomem(&tree);

}

static unsigned long get_last_index(struct ma_state *mas)

{

	struct maple_node *node = mas_mn(mas);

	enum maple_type mt = mte_node_type(mas->node);

	unsigned long *pivots = ma_pivots(node, mt);

	unsigned long last_index = mas_data_end(mas);

	BUG_ON(last_index == 0);

	return pivots[last_index - 1] + 1;

}

/*

 * Assert that we handle spanning stores that consume the entirety of the right

 * leaf node correctly.

 */

static void test_spanning_store_regression(void)

{

	unsigned long from = 0, to = 0;

	DEFINE_MTREE(tree);

	MA_STATE(mas, &tree, 0, 0);

	/*

	 * Build a 3-level tree. We require a parent node below the root node

	 * and 2 leaf nodes under it, so we can span the entirety of the right

	 * hand node.

	 */

	build_full_tree(&tree, 0, 3);

	/* Descend into position at depth 2. */

	mas_reset(&mas);

	mas_start(&mas);

	mas_descend(&mas);

	mas_descend(&mas);

	/*

	 * We need to establish a tree like the below.

	 *

	 * Then we can try a store in [from, to] which results in a spanned

	 * store across nodes B and C, with the maple state at the time of the

	 * write being such that only the subtree at A and below is considered.

	 *

	 * Height

	 *  0                              Root Node

	 *                                  /      \

	 *                    pivot = to   /        \ pivot = ULONG_MAX

	 *                                /          \

	 *   1                       A [-----]       ...

	 *                              /   \

	 *                pivot = from /     \ pivot = to

	 *                            /       \

	 *   2 (LEAVES)          B [-----]  [-----] C

	 *                                       ^--- Last pivot to.

	 */

	while (true) {

		unsigned long tmp = get_last_index(&mas);

		if (mas_next_sibling(&mas)) {

			from = tmp;

			to = mas.max;

		} else {

			break;

		}

	}

	BUG_ON(from == 0 && to == 0);

	/* Perform the store. */

	mas_set_range(&mas, from, to);

	mas_store_gfp(&mas, xa_mk_value(0xdead), GFP_KERNEL);

	/* If the regression occurs, the validation will fail. */

	mt_validate(&tree);

	/* Cleanup. */

	__mt_destroy(&tree);

}

static void regression_tests(void)

{

	test_spanning_store_regression();

}

void maple_tree_tests(void)

{

#if !defined(BENCH)

	regression_tests();

	farmer_tests();

#endif

	maple_tree_seed();