From: Liam R. Howlett <Liam.Howlett@Oracle.com>
Date: Thu, 13 Aug 2020 16:29:42 +0000 (-0400)
Subject: maple_tree: Fix mas_awalk gap issues
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=fa5eaf3a0b37ae1a61faa6fa9d97a1460bd58409;p=users%2Fjedix%2Flinux-maple.git

maple_tree: Fix mas_awalk gap issues

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

diff --git a/lib/maple_tree.c b/lib/maple_tree.c
index 06807be04e563..22a60dcfe0e94 100644
--- a/lib/maple_tree.c
+++ b/lib/maple_tree.c
@@ -3621,7 +3621,7 @@ ascend:
 static inline bool _mas_awalk(struct ma_state *mas, unsigned long size)
 {
 	enum maple_type type = mte_node_type(mas->node);
-	unsigned long pivot, min, gap;
+	unsigned long pivot, min, gap = 0;
 	unsigned char slot = 0, pivot_cnt = mt_pivots[type];
 	bool found = false;
 
@@ -3641,23 +3641,15 @@ static inline bool _mas_awalk(struct ma_state *mas, unsigned long size)
 				goto next_slot;
 
 			if (ma_is_leaf(type)) {
-				if (!mt_is_empty(mas_get_rcu_slot(mas, slot)))
-					goto next_slot;
-
-				gap = pivot - mas->index;
-				if (!gap) // No entry, pivot = index.
-					gap = 1;
-
-				if (mas->last + size < pivot - gap) { // upper bound
-					mas_set_err(mas, -EBUSY);
-					return true;
-				}
-				if (mas->last < pivot - gap) // gap check
-					break;
+				gap = 0;
+				if (mt_is_empty(mas_get_rcu_slot(mas, slot)))
+					gap = min(pivot, mas->last) -
+						max(mas->index, min) + 1;
 			} else {
 				gap = mte_get_gap(mas->node, slot);
 			}
 
+next_slot:
 			if (gap >= size) {
 				if (ma_is_leaf(type)) {
 					found = true;
@@ -3670,7 +3662,6 @@ static inline bool _mas_awalk(struct ma_state *mas, unsigned long size)
 					break;
 				}
 			}
-next_slot:
 			min = pivot + 1;
 			if (mas->last < min) {
 				mas_set_err(mas, -EBUSY);