From: Liam R. Howlett <Liam.Howlett@Oracle.com>
Date: Thu, 10 Jan 2019 20:18:01 +0000 (-0500)
Subject: maple_tree: Avoid coalescing on insert if it is not needed.
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=bbd08f83d3c07e136c2621a57d5d22dea000fa3b;p=users%2Fjedix%2Flinux-maple.git

maple_tree: Avoid coalescing on insert if it is not needed.

On insert, iterate over the pivots looking for matching ones to
determine if slots need to be coalesced.
Erase always needs to coalesce, so don't check there.

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

diff --git a/lib/maple_tree.c b/lib/maple_tree.c
index 343a7996765b4..c088620ffad72 100644
--- a/lib/maple_tree.c
+++ b/lib/maple_tree.c
@@ -564,7 +564,12 @@ bool ma_reserved(void *entry)
  */
 void mt_replace(struct ma_state *mas, void *p_entry, bool leaf)
 {
-	struct maple_node *mn = mt_to_node(mas->node);
+	struct maple_node *mn;
+
+	if (mas->node == p_entry)
+		return;
+
+	mn = mt_to_node(mas->node);
 	mn->parent = mt_to_node(p_entry)->parent;
 	if (!leaf)
 		ma_adopt_children(mn);
@@ -579,13 +584,18 @@ void mt_replace(struct ma_state *mas, void *p_entry, bool leaf)
 
 		RCU_INIT_POINTER(parent->slot[slot], mas->node);
 	}
-	mt_free(mt_to_node(p_entry));
 
+	mt_free(mt_to_node(p_entry));
 }
+
 void *ma_insert(struct ma_state *mas, void *entry)
 {
 	void *p_entry; // Previous entry.
 	unsigned char slot = MAPLE_NODE_SLOTS;
+	unsigned long last = mas->max;
+	struct maple_range_64 *src;
+	bool coalesce = false;
+	unsigned char s_slot;
 	bool leaf;
 
 
@@ -608,17 +618,28 @@ void *ma_insert(struct ma_state *mas, void *entry)
 
 	leaf = _mas_walk(mas);
 	slot = ma_get_slot(mas);
+	src = mt_to_node(mas->node);
 	if (leaf == true && slot != MAPLE_NODE_SLOTS) {
-		if (mt_to_node(mas->node)->slot[slot]) {
+		if (src->slot[slot]) {
 			mas_set_err(mas, -EEXIST);
 			goto exists;
 		}
 	}
 
 	p_entry = mas->node;
-	mas_coalesce(mas);
-	if (mas_is_err(mas))
-		goto error;
+	for (s_slot = 0; s_slot < MAPLE_RANGE64_SLOTS - 1; s_slot++) {
+		if (last == src->pivot[s_slot]) {
+			coalesce = true;
+			break;
+		}
+		last = src->pivot[s_slot];
+	}
+
+	if (coalesce) {
+		mas_coalesce(mas);
+		if (mas_is_err(mas))
+			goto error;
+	}
 
 	/* Do the insert */
 	_ma_insert(mas, entry, slot);
@@ -711,6 +732,7 @@ int ma_erase(struct ma_state *mas)
 	mas_coalesce(mas);
 	if (mas_is_err(mas))
 		goto error;
+
 	mt_replace(mas, p_entry, leaf);
 
 error:
@@ -940,6 +962,7 @@ void mt_dump(const struct maple_tree *mt)
 	else
 		mt_dump_node(entry, 0, mt_max[mt_node_type(entry)], 0);
 }
+
 void mt_set_non_kernel(unsigned int val)
 {
 	kmem_cache_set_non_kernel(maple_node_cache, val);