1 files changed, 47 insertions, 33 deletions

diff --git a/fs/btrfs/ulist.c b/fs/btrfs/ulist.c
index 183863f4bfa4..7e16a253fb35 100644
--- a/fs/btrfs/ulist.c
+++ b/fs/btrfs/ulist.c
@@ -50,6 +50,7 @@ void ulist_init(struct ulist *ulist)
 	INIT_LIST_HEAD(&ulist->nodes);
 	ulist->root = RB_ROOT;
 	ulist->nnodes = 0;
+	ulist->prealloc = NULL;
 }
 
 /*
@@ -68,6 +69,8 @@ void ulist_release(struct ulist *ulist)
 	list_for_each_entry_safe(node, next, &ulist->nodes, list) {
 		kfree(node);
 	}
+	kfree(ulist->prealloc);
+	ulist->prealloc = NULL;
 	ulist->root = RB_ROOT;
 	INIT_LIST_HEAD(&ulist->nodes);
 }
@@ -105,6 +108,12 @@ struct ulist *ulist_alloc(gfp_t gfp_mask)
 	return ulist;
 }
 
+void ulist_prealloc(struct ulist *ulist, gfp_t gfp_mask)
+{
+	if (!ulist->prealloc)
+		ulist->prealloc = kzalloc(sizeof(*ulist->prealloc), gfp_mask);
+}
+
 /*
  * Free dynamically allocated ulist.
  *
@@ -120,21 +129,25 @@ void ulist_free(struct ulist *ulist)
 	kfree(ulist);
 }
 
+static int ulist_node_val_key_cmp(const void *key, const struct rb_node *node)
+{
+	const u64 *val = key;
+	const struct ulist_node *unode = rb_entry(node, struct ulist_node, rb_node);
+
+	if (unode->val < *val)
+		return 1;
+	else if (unode->val > *val)
+		return -1;
+
+	return 0;
+}
+
 static struct ulist_node *ulist_rbtree_search(struct ulist *ulist, u64 val)
 {
-	struct rb_node *n = ulist->root.rb_node;
-	struct ulist_node *u = NULL;
-
-	while (n) {
-		u = rb_entry(n, struct ulist_node, rb_node);
-		if (u->val < val)
-			n = n->rb_right;
-		else if (u->val > val)
-			n = n->rb_left;
-		else
-			return u;
-	}
-	return NULL;
+	struct rb_node *node;
+
+	node = rb_find(&val, &ulist->root, ulist_node_val_key_cmp);
+	return rb_entry_safe(node, struct ulist_node, rb_node);
 }
 
 static void ulist_rbtree_erase(struct ulist *ulist, struct ulist_node *node)
@@ -146,25 +159,20 @@ static void ulist_rbtree_erase(struct ulist *ulist, struct ulist_node *node)
 	ulist->nnodes--;
 }
 
+static int ulist_node_val_cmp(struct rb_node *new, const struct rb_node *existing)
+{
+	const struct ulist_node *unode = rb_entry(new, struct ulist_node, rb_node);
+
+	return ulist_node_val_key_cmp(&unode->val, existing);
+}
+
 static int ulist_rbtree_insert(struct ulist *ulist, struct ulist_node *ins)
 {
-	struct rb_node **p = &ulist->root.rb_node;
-	struct rb_node *parent = NULL;
-	struct ulist_node *cur = NULL;
-
-	while (*p) {
-		parent = *p;
-		cur = rb_entry(parent, struct ulist_node, rb_node);
-
-		if (cur->val < ins->val)
-			p = &(*p)->rb_right;
-		else if (cur->val > ins->val)
-			p = &(*p)->rb_left;
-		else
-			return -EEXIST;
-	}
-	rb_link_node(&ins->rb_node, parent, p);
-	rb_insert_color(&ins->rb_node, &ulist->root);
+	struct rb_node *node;
+
+	node = rb_find_add(&ins->rb_node, &ulist->root, ulist_node_val_cmp);
+	if (node)
+		return -EEXIST;
 	return 0;
 }
 
@@ -206,9 +214,15 @@ int ulist_add_merge(struct ulist *ulist, u64 val, u64 aux,
 			*old_aux = node->aux;
 		return 0;
 	}
-	node = kmalloc(sizeof(*node), gfp_mask);
-	if (!node)
-		return -ENOMEM;
+
+	if (ulist->prealloc) {
+		node = ulist->prealloc;
+		ulist->prealloc = NULL;
+	} else {
+		node = kmalloc(sizeof(*node), gfp_mask);
+		if (!node)
+			return -ENOMEM;
+	}
 
 	node->val = val;
 	node->aux = aux;