diff -r eb4767aa190e ref-cache.c
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/ref-cache.c	Fri Jul 25 21:56:56 2008 +0800
@@ -0,0 +1,195 @@
+/*
+ * Copyright (C) 2008 Oracle.  All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License v2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this program; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 021110-1307, USA.
+ */
+
+#include "ctree.h"
+#include "ref-cache.h"
+#include "transaction.h"
+
+struct btrfs_leaf_ref *btrfs_alloc_leaf_ref(int nr_extents)
+{
+	struct btrfs_leaf_ref *ref;
+
+	ref = kmalloc(btrfs_leaf_ref_size(nr_extents), GFP_NOFS);
+	if (ref) {
+		memset(ref, 0, sizeof(*ref));
+		atomic_set(&ref->usage, 1);
+	}
+	return ref;
+}
+
+void btrfs_free_leaf_ref(struct btrfs_leaf_ref *ref)
+{
+	if (!ref)
+		return;
+	WARN_ON(atomic_read(&ref->usage) == 0);
+	if (atomic_dec_and_test(&ref->usage)) {
+		BUG_ON(ref->in_tree);
+		kfree(ref);
+	}
+}
+
+static int comp_keys(struct btrfs_key *k1, struct btrfs_key *k2)
+{
+	if (k1->objectid > k2->objectid)
+		return 1;
+	if (k1->objectid < k2->objectid)
+		return -1;
+	if (k1->type > k2->type)
+		return 1;
+	if (k1->type < k2->type)
+		return -1;
+	if (k1->offset > k2->offset)
+		return 1;
+	if (k1->offset < k2->offset)
+		return -1;
+	return 0;
+}
+
+static struct rb_node *tree_insert(struct rb_root *root, struct btrfs_key *key,
+				   struct rb_node *node)
+{
+	struct rb_node ** p = &root->rb_node;
+	struct rb_node * parent = NULL;
+	struct btrfs_leaf_ref *entry;
+	int ret;
+
+	while(*p) {
+		parent = *p;
+		entry = rb_entry(parent, struct btrfs_leaf_ref, rb_node);
+		WARN_ON(!entry->in_tree);
+
+		ret = comp_keys(key, &entry->key);
+		if (ret < 0)
+			p = &(*p)->rb_left;
+		else if (ret > 0)
+			p = &(*p)->rb_right;
+		else
+			return parent;
+	}
+	
+	entry = rb_entry(node, struct btrfs_leaf_ref, rb_node);
+	entry->in_tree = 1;
+	rb_link_node(node, parent, p);
+	rb_insert_color(node, root);
+	return NULL;
+}
+
+static struct rb_node *tree_search(struct rb_root *root, struct btrfs_key *key)
+{
+	struct rb_node * n = root->rb_node;
+	struct btrfs_leaf_ref *entry;
+	int ret;
+
+	while(n) {
+		entry = rb_entry(n, struct btrfs_leaf_ref, rb_node);
+		WARN_ON(!entry->in_tree);
+
+		ret = comp_keys(key, &entry->key);
+		if (ret < 0)
+			n = n->rb_left;
+		else if (ret > 0)
+			n = n->rb_right;
+		else
+			return n;
+	}
+	return NULL;
+}
+
+struct btrfs_leaf_ref *btrfs_lookup_leaf_ref(struct btrfs_root *root,
+					     struct btrfs_key *key)
+{
+	struct rb_node *rb;
+	struct btrfs_leaf_ref *ref = NULL;
+	struct btrfs_leaf_ref_tree *tree = root->ref_tree;
+
+	if (!tree)
+		return NULL;
+
+	spin_lock(&tree->lock);
+	if (tree->last && comp_keys(key, &tree->last->key) == 0) {
+		ref = tree->last;
+	} else {
+		rb = tree_search(&tree->root, key);
+		if (rb) {
+			ref = rb_entry(rb, struct btrfs_leaf_ref, rb_node);
+			tree->last = ref;
+		}
+	}
+	if (ref)
+		atomic_inc(&ref->usage);
+	spin_unlock(&tree->lock);
+	return ref;
+}
+
+int btrfs_add_leaf_ref(struct btrfs_root *root, struct btrfs_leaf_ref *ref)
+{
+	int ret = 0;
+	struct rb_node *rb;
+	size_t size = btrfs_leaf_ref_size(ref->nritems);
+	struct btrfs_leaf_ref_tree *tree = root->ref_tree;
+	struct btrfs_transaction *trans = root->fs_info->running_transaction;
+
+	spin_lock(&tree->lock);
+	rb = tree_insert(&tree->root, &ref->key, &ref->rb_node);
+	if (rb) {
+		ret = -EEXIST;
+	} else {
+		spin_lock(&root->fs_info->ref_cache_lock);
+		root->fs_info->total_ref_cache_size += size;
+		if (trans && tree->generation == trans->transid)
+			root->fs_info->running_ref_cache_size += size;
+		spin_unlock(&root->fs_info->ref_cache_lock);
+
+		tree->last = ref;
+		atomic_inc(&ref->usage);
+	}
+	spin_unlock(&tree->lock);
+	return ret;
+}
+
+int btrfs_remove_leaf_ref(struct btrfs_root *root, struct btrfs_leaf_ref *ref)
+{
+	size_t size = btrfs_leaf_ref_size(ref->nritems);
+	struct btrfs_leaf_ref_tree *tree = root->ref_tree;
+	struct btrfs_transaction *trans = root->fs_info->running_transaction;
+
+	BUG_ON(!ref->in_tree);
+	spin_lock(&tree->lock);
+	rb_erase(&ref->rb_node, &tree->root);
+	ref->in_tree = 0;
+	
+	spin_lock(&root->fs_info->ref_cache_lock);
+	root->fs_info->total_ref_cache_size -= size;
+	if (trans && tree->generation == trans->transid)
+		root->fs_info->running_ref_cache_size -= size;
+	spin_unlock(&root->fs_info->ref_cache_lock);
+
+	if (tree->last == ref) {
+		struct rb_node *next = rb_next(&ref->rb_node);
+		if (next) {
+			tree->last = rb_entry(next, struct btrfs_leaf_ref,
+					      rb_node);
+		} else
+			tree->last = NULL;
+	}
+	spin_unlock(&tree->lock);
+
+	btrfs_free_leaf_ref(ref);
+	return 0;
+}
+
diff -r eb4767aa190e ref-cache.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/ref-cache.h	Fri Jul 25 21:58:24 2008 +0800
@@ -0,0 +1,71 @@
+/*
+ * Copyright (C) 2008 Oracle.  All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License v2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this program; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 021110-1307, USA.
+ */
+
+struct btrfs_extent_info {
+	u64 bytenr;
+	u64 num_bytes;
+	u64 objectid;
+	u64 offset;
+};
+
+struct btrfs_leaf_ref {
+	struct rb_node rb_node;
+	struct btrfs_key key;
+	int in_tree;
+	atomic_t usage;
+
+	u64 bytenr;
+	u64 owner;
+	u64 generation;
+	int nritems;
+	struct btrfs_extent_info extents[];
+};
+
+struct btrfs_leaf_ref_tree {
+	struct rb_root root;
+	struct btrfs_leaf_ref *last;
+	u64 generation;
+	spinlock_t lock;
+};
+
+static inline size_t btrfs_leaf_ref_size(int nr_extents)
+{
+	return sizeof(struct btrfs_leaf_ref) + 
+	       sizeof(struct btrfs_extent_info) * nr_extents;
+}
+
+static inline void btrfs_leaf_ref_tree_init(struct btrfs_leaf_ref_tree *tree)
+{
+	tree->root.rb_node = NULL;
+	tree->last = NULL;
+	tree->generation = 0;
+	spin_lock_init(&tree->lock);
+}
+
+static inline int btrfs_leaf_ref_tree_empty(struct btrfs_leaf_ref_tree *tree)
+{
+	return RB_EMPTY_ROOT(&tree->root);
+}
+
+void btrfs_leaf_ref_tree_init(struct btrfs_leaf_ref_tree *tree);
+struct btrfs_leaf_ref *btrfs_alloc_leaf_ref(int nr_extents);
+void btrfs_free_leaf_ref(struct btrfs_leaf_ref *ref);
+struct btrfs_leaf_ref *btrfs_lookup_leaf_ref(struct btrfs_root *root,
+					     struct btrfs_key *key);
+int btrfs_add_leaf_ref(struct btrfs_root *root, struct btrfs_leaf_ref *ref);
+int btrfs_remove_leaf_ref(struct btrfs_root *root, struct btrfs_leaf_ref *ref);