maple_tree: use height and depth consistently

For the maple tree, the root node is defined to have a depth of 0 with a
height of 1.  Each level down from the node, these values are incremented
by 1.  Various code paths define a root with depth 1 which is inconsisent
with the definition.  Modify the code to be consistent with this
definition.

In mas_spanning_rebalance(), l_mas.depth was being used to track the
height based on the number of iterations done in the main loop.  This
information was then used in mas_put_in_tree() to set the height.  Rather
than overload the l_mas.depth field to track height, simply keep track of
height in the local variable new_height and directly pass this to
mas_wmb_replace() which will be passed into mas_put_in_tree().  This
allows up to remove writes to l_mas.depth.

Link: https://lkml.kernel.org/r/20250410191446.2474640-3-sidhartha.kumar@oracle.com
Signed-off-by: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Wei Yang <richard.weiyang@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

1 files changed, 19 insertions, 0 deletions

diff --git a/tools/testing/radix-tree/maple.c b/tools/testing/radix-tree/maple.c
index bc30050227fd..e0f8fabe8821 100644
--- a/tools/testing/radix-tree/maple.c
+++ b/tools/testing/radix-tree/maple.c
@@ -36248,6 +36248,21 @@ static noinline void __init check_mtree_dup(struct maple_tree *mt)
 
 extern void test_kmem_cache_bulk(void);
 
+static inline void check_spanning_store_height(struct maple_tree *mt)
+{
+	int index = 0;
+	MA_STATE(mas, mt, 0, 0);
+	mas_lock(&mas);
+	while (mt_height(mt) != 3) {
+		mas_store_gfp(&mas, xa_mk_value(index), GFP_KERNEL);
+		mas_set(&mas, ++index);
+	}
+	mas_set_range(&mas, 90, 140);
+	mas_store_gfp(&mas, xa_mk_value(index), GFP_KERNEL);
+	MT_BUG_ON(mt, mas_mt_height(&mas) != 2);
+	mas_unlock(&mas);
+}
+
 /* callback function used for check_nomem_writer_race() */
 static void writer2(void *maple_tree)
 {
@@ -36415,6 +36430,10 @@ void farmer_tests(void)
 	mtree_destroy(&tree);
 
 	mt_init_flags(&tree, MT_FLAGS_ALLOC_RANGE);
+	check_spanning_store_height(&tree);
+	mtree_destroy(&tree);
+
+	mt_init_flags(&tree, MT_FLAGS_ALLOC_RANGE);
 	check_null_expand(&tree);
 	mtree_destroy(&tree);