maple_tree: add a test checking storing null

Add a test to assert that, when storing null to am empty tree or a
single entry tree it will not result into:

  * a root node with range [0, ULONG_MAX] set to NULL
  * a root node with consecutive slot set to NULL

Link: https://lkml.kernel.org/r/20241031231627.14316-6-richard.weiyang@gmail.com
Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Cc: Liam R. Howlett <Liam.Howlett@Oracle.com>
Cc: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/lib/test_maple_tree.c b/lib/test_maple_tree.c
index 31561e0e1a0d4aaf42342e04913355615eb44092..6f76093170bb848605904b604ad0efee09a65d6a 100644 (file)
--- a/lib/test_maple_tree.c
+++ b/lib/test_maple_tree.c
@@ -1387,6 +1387,92 @@ static noinline void __init check_prev_entry(struct maple_tree *mt)
        mas_unlock(&mas);
 }
 
+static noinline void __init check_store_null(struct maple_tree *mt)
+{
+       MA_STATE(mas, mt, 0, ULONG_MAX);
+
+       /*
+        * Store NULL at range [0, ULONG_MAX] to an empty tree should result
+        * in an empty tree
+        */
+       mt_init_flags(mt, MT_FLAGS_ALLOC_RANGE);
+       mas_lock(&mas);
+       mas_store_gfp(&mas, NULL, GFP_KERNEL);
+       MT_BUG_ON(mt, !mtree_empty(mt));
+       mas_unlock(&mas);
+       mtree_destroy(mt);
+
+       /*
+        * Store NULL at any range to an empty tree should result in an empty
+        * tree
+        */
+       mt_init_flags(mt, MT_FLAGS_ALLOC_RANGE);
+       mas_lock(&mas);
+       mas_set_range(&mas, 3, 10);
+       mas_store_gfp(&mas, NULL, GFP_KERNEL);
+       MT_BUG_ON(mt, !mtree_empty(mt));
+       mas_unlock(&mas);
+       mtree_destroy(mt);
+
+       /*
+        * Store NULL at range [0, ULONG_MAX] to a single entry tree should
+        * result in an empty tree
+        */
+       mt_init_flags(mt, MT_FLAGS_ALLOC_RANGE);
+       mas_lock(&mas);
+       mas_set(&mas, 0);
+       mas_store_gfp(&mas, &mas, GFP_KERNEL);
+       mas_set_range(&mas, 0, ULONG_MAX);
+       mas_store_gfp(&mas, NULL, GFP_KERNEL);
+       MT_BUG_ON(mt, !mtree_empty(mt));
+       mas_unlock(&mas);
+       mtree_destroy(mt);
+
+       /*
+        * Store NULL at range [0, n] to a single entry tree should
+        * result in an empty tree
+        */
+       mt_init_flags(mt, MT_FLAGS_ALLOC_RANGE);
+       mas_lock(&mas);
+       mas_set(&mas, 0);
+       mas_store_gfp(&mas, &mas, GFP_KERNEL);
+       mas_set_range(&mas, 0, 5);
+       mas_store_gfp(&mas, NULL, GFP_KERNEL);
+       MT_BUG_ON(mt, !mtree_empty(mt));
+       mas_unlock(&mas);
+       mtree_destroy(mt);
+
+       /*
+        * Store NULL at range [m, n] where m > 0 to a single entry tree
+        * should still be a single entry tree
+        */
+       mt_init_flags(mt, MT_FLAGS_ALLOC_RANGE);
+       mas_lock(&mas);
+       mas_set(&mas, 0);
+       mas_store_gfp(&mas, &mas, GFP_KERNEL);
+       mas_set_range(&mas, 2, 5);
+       mas_store_gfp(&mas, NULL, GFP_KERNEL);
+       MT_BUG_ON(mt, mtree_empty(mt));
+       MT_BUG_ON(mt, xa_is_node(mas_root(&mas)));
+       mas_unlock(&mas);
+       mtree_destroy(mt);
+
+       /*
+        * Store NULL at range [0, ULONG_MAX] to a tree with node should
+        * result in an empty tree
+        */
+       mt_init_flags(mt, MT_FLAGS_ALLOC_RANGE);
+       mas_lock(&mas);
+       mas_set_range(&mas, 1, 3);
+       mas_store_gfp(&mas, &mas, GFP_KERNEL);
+       MT_BUG_ON(mt, !xa_is_node(mas_root(&mas)));
+       mas_set_range(&mas, 0, ULONG_MAX);
+       mas_store_gfp(&mas, NULL, GFP_KERNEL);
+       MT_BUG_ON(mt, !mtree_empty(mt));
+       mas_unlock(&mas);
+       mtree_destroy(mt);
+}
+
 static noinline void __init check_root_expand(struct maple_tree *mt)
 {
        MA_STATE(mas, mt, 0, 0);
@@ -3710,6 +3796,10 @@ static int __init maple_tree_seed(void)
        goto skip;
 #endif
 
+       mt_init_flags(&tree, MT_FLAGS_ALLOC_RANGE);
+       check_store_null(&tree);
+       mtree_destroy(&tree);
+
        mt_init_flags(&tree, MT_FLAGS_ALLOC_RANGE);
        check_root_expand(&tree);
        mtree_destroy(&tree);