From: Liam R. Howlett <Liam.Howlett@Oracle.com>
Date: Fri, 11 Jan 2019 02:01:25 +0000 (-0500)
Subject: maple_tree: Avoid allocating a node in coalescing until necessary
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=8f66e5c0aa3ea6410da4f2f938fccd94e50290ea;p=users%2Fjedix%2Flinux-maple.git

maple_tree: Avoid allocating a node in coalescing until necessary

When looping through a node, don't create a new node if there is no need
to do so.

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

diff --git a/lib/maple_tree.c b/lib/maple_tree.c
index c088620ffad7..13958fa73eb9 100644
--- a/lib/maple_tree.c
+++ b/lib/maple_tree.c
@@ -446,31 +446,47 @@ static int mas_coalesce(struct ma_state *mas)
 	struct maple_range_64 *src = &mt_to_node(mas->node)->mr64;
 	unsigned char s_slot, d_slot = 0;
 	unsigned long last = mas->max;
-	struct maple_range_64 *dst;
+	struct maple_range_64 *dst = NULL;
 	struct maple_node *mn;
 
-	/* Allocate a new node */
-	mas_node_cnt(mas, 1);
-	if (mas_is_err(mas))
-		return 0;
-
-	mn = ma_next_alloc(mas);
-	dst = &mn->mr64;
-	mas->node = mt_mk_node(mn, maple_leaf_64);
 
 	for (s_slot = 0; s_slot < MAPLE_RANGE64_SLOTS; s_slot++) {
 		if (s_slot < MAPLE_RANGE64_SLOTS - 1) {
-			if (last == src->pivot[s_slot])
+			if (last == src->pivot[s_slot]) {
+				if (!dst) {
+					int i = 0;
+					/* Allocate a new node */
+					mas_node_cnt(mas, 1);
+					if (mas_is_err(mas))
+						return 0;
+
+					mn = ma_next_alloc(mas);
+					dst = &mn->mr64;
+					mn->parent = src->parent;
+					for (i = 0; i <= s_slot;i++)
+					{
+						RCU_INIT_POINTER(dst->slot[i],
+								 src->slot[i]);
+						dst->pivot[i] = src->pivot[i];
+					}
+					d_slot = s_slot;
+					mas->node = mt_mk_node(mn,
+							       maple_leaf_64);
+				}
 				continue;
+			}
 
 			if (s_slot != 0 && src->pivot[s_slot] == 0)
 				break;
 
-			dst->pivot[d_slot] = src->pivot[s_slot];
-		}
+			last = src->pivot[s_slot];
 
-		RCU_INIT_POINTER(dst->slot[d_slot], src->slot[s_slot]);
-		last = dst->pivot[d_slot++];
+			if (dst)
+				dst->pivot[d_slot] = src->pivot[s_slot];
+		}
+		if (dst)
+			RCU_INIT_POINTER(dst->slot[d_slot++],
+					 src->slot[s_slot]);
 	}
 	return s_slot - d_slot;
 }