From: Liam R. Howlett <Liam.Howlett@oracle.com>
Date: Mon, 17 Apr 2023 16:10:57 +0000 (-0400)
Subject: maple_tree: Avoid unnecessary ascending
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=5620a4d985f2bdcf292a020cdac0037d9dfa52fd;p=users%2Fjedix%2Flinux-maple.git

maple_tree: Avoid unnecessary ascending

The maple tree node limits are implied by the parent.  When walking up
the tree, the limit may not be known until a slot that does not have
implied limits are encountered.  However, if the node is the left-most
or right-most node, the walking up to find that limit can be skipped.

This commit also fixes the debug/testing code that was not setting the
limit on walking down the tree as that optimization is not compatible
with this change.

Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
---

diff --git a/lib/maple_tree.c b/lib/maple_tree.c
index ac0245dd88dad..60bae5be008a6 100644
--- a/lib/maple_tree.c
+++ b/lib/maple_tree.c
@@ -1132,6 +1132,12 @@ static int mas_ascend(struct ma_state *mas)
 		return 0;
 	}
 
+	if (!mas->min)
+		set_min = true;
+
+	if (mas->max == ULONG_MAX)
+		set_max = true;
+
 	min = 0;
 	max = ULONG_MAX;
 	do {
diff --git a/tools/testing/radix-tree/maple.c b/tools/testing/radix-tree/maple.c
index 9286d3baa12d6..75df543e019c9 100644
--- a/tools/testing/radix-tree/maple.c
+++ b/tools/testing/radix-tree/maple.c
@@ -35259,6 +35259,7 @@ static void mas_dfs_preorder(struct ma_state *mas)
 
 	struct maple_enode *prev;
 	unsigned char end, slot = 0;
+	unsigned long *pivots;
 
 	if (mas->node == MAS_START) {
 		mas_start(mas);
@@ -35291,6 +35292,9 @@ walk_up:
 		mas_ascend(mas);
 		goto walk_up;
 	}
+	pivots = ma_pivots(mte_to_node(prev), mte_node_type(prev));
+	mas->max = mas_safe_pivot(mas, pivots, slot, mte_node_type(prev));
+	mas->min = mas_safe_min(mas, pivots, slot);
 
 	return;
 done: