test_maple_tree: testing the cyclic allocation

This tests the interactions of the cyclic allocations, the maple state
index and last, and overflow.

Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Link: https://lore.kernel.org/r/170820144894.6328.13052830860966450674.stgit@91.116.238.104.host.secureserver.net
Signed-off-by: Christian Brauner <brauner@kernel.org>

Author: howlett

lib/test_maple_tree.c

@@ -3599,6 +3599,45 @@ static noinline void __init check_state_handling(struct maple_tree *mt)
 	mas_unlock(&mas);
 }
 
+static noinline void __init alloc_cyclic_testing(struct maple_tree *mt)
+{
+	unsigned long location;
+	unsigned long next;
+	int ret = 0;
+	MA_STATE(mas, mt, 0, 0);
+
+	next = 0;
+	mtree_lock(mt);
+	for (int i = 0; i < 100; i++) {
+		mas_alloc_cyclic(&mas, &location, mt, 2, ULONG_MAX, &next, GFP_KERNEL);
+		MAS_BUG_ON(&mas, i != location - 2);
+		MAS_BUG_ON(&mas, mas.index != location);
+		MAS_BUG_ON(&mas, mas.last != location);
+		MAS_BUG_ON(&mas, i != next - 3);
+	}
+
+	mtree_unlock(mt);
+	mtree_destroy(mt);
+	next = 0;
+	mt_init_flags(mt, MT_FLAGS_ALLOC_RANGE);
+	for (int i = 0; i < 100; i++) {
+		mtree_alloc_cyclic(mt, &location, mt, 2, ULONG_MAX, &next, GFP_KERNEL);
+		MT_BUG_ON(mt, i != location - 2);
+		MT_BUG_ON(mt, i != next - 3);
+		MT_BUG_ON(mt, mtree_load(mt, location) != mt);
+	}
+
+	mtree_destroy(mt);
+	/* Overflow test */
+	next = ULONG_MAX - 1;
+	ret = mtree_alloc_cyclic(mt, &location, mt, 2, ULONG_MAX, &next, GFP_KERNEL);
+	MT_BUG_ON(mt, ret != 0);
+	ret = mtree_alloc_cyclic(mt, &location, mt, 2, ULONG_MAX, &next, GFP_KERNEL);
+	MT_BUG_ON(mt, ret != 0);
+	ret = mtree_alloc_cyclic(mt, &location, mt, 2, ULONG_MAX, &next, GFP_KERNEL);
+	MT_BUG_ON(mt, ret != 1);
+}
+
 static DEFINE_MTREE(tree);
 static int __init maple_tree_seed(void)
 {
@@ -3880,6 +3919,11 @@ static int __init maple_tree_seed(void)
 	check_state_handling(&tree);
 	mtree_destroy(&tree);
 
+	mt_init_flags(&tree, MT_FLAGS_ALLOC_RANGE);
+	alloc_cyclic_testing(&tree);
+	mtree_destroy(&tree);
+
+
 #if defined(BENCH)
 skip:
 #endif