From: Liam R. Howlett <Liam.Howlett@Oracle.com>
Date: Mon, 7 Dec 2020 00:53:05 +0000 (-0500)
Subject: maple_tree: mas_first_entry() optimization
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=a9078db976b69596ec66aa0a5aabdd4140377154;p=users%2Fjedix%2Flinux-maple.git

maple_tree: mas_first_entry() optimization

Remove loop in favour of checking pivot 0 or 1 as one mus have a value.

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

diff --git a/lib/maple_tree.c b/lib/maple_tree.c
index 8d8e16f8eb36..f3cc0b571789 100644
--- a/lib/maple_tree.c
+++ b/lib/maple_tree.c
@@ -1275,9 +1275,12 @@ static inline void mas_update_gap(struct ma_state *mas)
 static inline unsigned long mas_first_entry(struct ma_state *mas,
 		unsigned long limit)
 {
-	void **slots, *entry;
 	unsigned long max = mas->max, range_start = mas->min;
 	unsigned char offset;
+	unsigned long *pivots;
+	struct maple_node *mn;
+	void **slots;
+	enum maple_type mt;
 
 	while (likely(!mte_is_leaf(mas->node))) {
 		max = mte_pivot(mas->node, 0);
@@ -1285,18 +1288,29 @@ static inline unsigned long mas_first_entry(struct ma_state *mas,
 	}
 
 	mas->max = max;
-	slots = ma_slots(mte_to_node(mas->node), mte_node_type(mas->node));
+	mn = mas_mn(mas);
+	mt = mte_node_type(mas->node);
+	slots = ma_slots(mn, mt);
 
+	/* 0 or 1 must be set */
 	offset = 0;
-	while ((range_start < limit) &&
-	       (offset < mt_slot_count(mas->node))) {
-		entry = mas_slot(mas, slots, offset);
-		if (entry)
-			goto done;
-		range_start = mas_safe_pivot(mas, offset) + 1;
-		offset++;
-	}
+	range_start = mas->min;
+	if (range_start > limit)
+		goto none;
+
+	if(likely(mas_slot(mas, slots, offset)))
+		goto done;
+
+	pivots = ma_pivots(mn, mt);
+	range_start = pivots[0] + 1;
+
+	if (range_start > limit)
+		goto none;
+
+	if(likely(mas_slot(mas, slots, ++offset)))
+		goto done;
 
+none:
 	mas->node = MAS_NONE;
 done:
 	mas->offset = offset;