diff --git a/fs/btrfs/Makefile b/fs/btrfs/Makefile
index a4e2df66bdbb74c2fbecdc1084b63240f63bcbe1..9321438c5eefec21a193ede271bd6a130d5fa774 100644
--- a/fs/btrfs/Makefile
+++ b/fs/btrfs/Makefile
@@ -4,7 +4,7 @@ ifneq ($(KERNELRELEASE),)
 obj-m  := btrfs.o
 btrfs-y := super.o ctree.o extent-tree.o print-tree.o root-tree.o dir-item.o \
 	   hash.o file-item.o inode-item.o inode-map.o disk-io.o \
-	   transaction.o bit-radix.o inode.o file.o
+	   transaction.o bit-radix.o inode.o file.o tree-defrag.o
 
 #btrfs-y := ctree.o disk-io.o radix-tree.o extent-tree.o print-tree.o \
 #	  root-tree.o dir-item.o hash.o file-item.o inode-item.o \
diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index 7a08491e208e1b788a550f99f9caae0a7a59f372..c7e47e77723ff413c5350a7949fdeb02500b3a4b 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -65,44 +65,44 @@ void btrfs_release_path(struct btrfs_root *root, struct btrfs_path *p)
 	memset(p, 0, sizeof(*p));
 }
 
-static int btrfs_cow_block(struct btrfs_trans_handle *trans, struct btrfs_root
+static int __btrfs_cow_block(struct btrfs_trans_handle *trans, struct btrfs_root
 			   *root, struct buffer_head *buf, struct buffer_head
 			   *parent, int parent_slot, struct buffer_head
-			   **cow_ret)
+			   **cow_ret, u64 search_start, u64 empty_size)
 {
 	struct buffer_head *cow;
 	struct btrfs_node *cow_node;
-	int ret;
+	int ret = 0;
+	int different_trans = 0;
 
+	WARN_ON(root->ref_cows && trans->transid != root->last_trans);
 	WARN_ON(!buffer_uptodate(buf));
-	if (trans->transaction != root->fs_info->running_transaction) {
-		printk(KERN_CRIT "trans %Lu running %Lu\n", trans->transid,
-		       root->fs_info->running_transaction->transid);
-		WARN_ON(1);
-	}
-	if (trans->transid != root->fs_info->generation) {
-		printk(KERN_CRIT "trans %Lu running %Lu\n", trans->transid,
-		       root->fs_info->generation);
-		WARN_ON(1);
-	}
-	if (btrfs_header_generation(btrfs_buffer_header(buf)) ==
-				    trans->transid) {
-		*cow_ret = buf;
-		return 0;
-	}
-	cow = btrfs_alloc_free_block(trans, root, buf->b_blocknr);
+	cow = btrfs_alloc_free_block(trans, root, search_start, empty_size);
 	if (IS_ERR(cow))
 		return PTR_ERR(cow);
+
 	cow_node = btrfs_buffer_node(cow);
 	if (buf->b_size != root->blocksize || cow->b_size != root->blocksize)
 		WARN_ON(1);
+
 	memcpy(cow_node, btrfs_buffer_node(buf), root->blocksize);
 	btrfs_set_header_blocknr(&cow_node->header, bh_blocknr(cow));
 	btrfs_set_header_generation(&cow_node->header, trans->transid);
 	btrfs_set_header_owner(&cow_node->header, root->root_key.objectid);
-	ret = btrfs_inc_ref(trans, root, buf);
-	if (ret)
-		return ret;
+
+	WARN_ON(btrfs_header_generation(btrfs_buffer_header(buf)) >
+		trans->transid);
+	if (btrfs_header_generation(btrfs_buffer_header(buf)) !=
+				    trans->transid) {
+		different_trans = 1;
+		ret = btrfs_inc_ref(trans, root, buf);
+		if (ret)
+			return ret;
+	} else {
+		WARN_ON(!root->ref_cows);
+		clean_tree_block(trans, root, buf);
+	}
+
 	if (buf == root->node) {
 		root->node = cow;
 		get_bh(cow);
@@ -114,6 +114,8 @@ static int btrfs_cow_block(struct btrfs_trans_handle *trans, struct btrfs_root
 		btrfs_set_node_blockptr(btrfs_buffer_node(parent), parent_slot,
 					bh_blocknr(cow));
 		btrfs_mark_buffer_dirty(parent);
+		WARN_ON(btrfs_header_generation(btrfs_buffer_header(parent)) !=
+				    trans->transid);
 		btrfs_free_extent(trans, root, bh_blocknr(buf), 1, 1);
 	}
 	btrfs_block_release(root, buf);
@@ -122,6 +124,115 @@ static int btrfs_cow_block(struct btrfs_trans_handle *trans, struct btrfs_root
 	return 0;
 }
 
+int btrfs_cow_block(struct btrfs_trans_handle *trans, struct btrfs_root
+			   *root, struct buffer_head *buf, struct buffer_head
+			   *parent, int parent_slot, struct buffer_head
+			   **cow_ret)
+{
+	u64 search_start;
+	if (trans->transaction != root->fs_info->running_transaction) {
+		printk(KERN_CRIT "trans %Lu running %Lu\n", trans->transid,
+		       root->fs_info->running_transaction->transid);
+		WARN_ON(1);
+	}
+	if (trans->transid != root->fs_info->generation) {
+		printk(KERN_CRIT "trans %Lu running %Lu\n", trans->transid,
+		       root->fs_info->generation);
+		WARN_ON(1);
+	}
+	if (btrfs_header_generation(btrfs_buffer_header(buf)) ==
+				    trans->transid) {
+		*cow_ret = buf;
+		return 0;
+	}
+
+	search_start = bh_blocknr(buf) & ~((u64)65535);
+	return __btrfs_cow_block(trans, root, buf, parent,
+				 parent_slot, cow_ret, search_start, 0);
+}
+
+static int close_blocks(u64 blocknr, u64 other)
+{
+	if (blocknr < other && other - blocknr < 8)
+		return 1;
+	if (blocknr > other && blocknr - other < 8)
+		return 1;
+	return 0;
+}
+
+int btrfs_realloc_node(struct btrfs_trans_handle *trans,
+		       struct btrfs_root *root, struct buffer_head *parent,
+		       int cache_only)
+{
+	struct btrfs_node *parent_node;
+	struct buffer_head *cur_bh;
+	struct buffer_head *tmp_bh;
+	u64 blocknr;
+	u64 search_start = 0;
+	u64 other;
+	u32 parent_nritems;
+	int start_slot;
+	int end_slot;
+	int i;
+	int err = 0;
+
+	if (trans->transaction != root->fs_info->running_transaction) {
+		printk(KERN_CRIT "trans %Lu running %Lu\n", trans->transid,
+		       root->fs_info->running_transaction->transid);
+		WARN_ON(1);
+	}
+	if (trans->transid != root->fs_info->generation) {
+		printk(KERN_CRIT "trans %Lu running %Lu\n", trans->transid,
+		       root->fs_info->generation);
+		WARN_ON(1);
+	}
+	parent_node = btrfs_buffer_node(parent);
+	parent_nritems = btrfs_header_nritems(&parent_node->header);
+
+	start_slot = 0;
+	end_slot = parent_nritems;
+
+	if (parent_nritems == 1)
+		return 0;
+
+	for (i = start_slot; i < end_slot; i++) {
+		int close = 1;
+		blocknr = btrfs_node_blockptr(parent_node, i);
+		if (i > 0) {
+			other = btrfs_node_blockptr(parent_node, i - 1);
+			close = close_blocks(blocknr, other);
+		}
+		if (close && i < end_slot - 1) {
+			other = btrfs_node_blockptr(parent_node, i + 1);
+			close = close_blocks(blocknr, other);
+		}
+		if (close)
+			continue;
+
+		cur_bh = btrfs_find_tree_block(root, blocknr);
+		if (!cur_bh || !buffer_uptodate(cur_bh) ||
+		    buffer_locked(cur_bh)) {
+			if (cache_only) {
+				brelse(cur_bh);
+				continue;
+			}
+			brelse(cur_bh);
+			cur_bh = read_tree_block(root, blocknr);
+		}
+		if (search_start == 0) {
+			search_start = bh_blocknr(cur_bh) & ~((u64)65535);
+		}
+		err = __btrfs_cow_block(trans, root, cur_bh, parent, i,
+					&tmp_bh, search_start,
+					min(8, end_slot - i));
+		if (err)
+			break;
+		search_start = bh_blocknr(tmp_bh);
+		brelse(tmp_bh);
+	}
+	return err;
+}
+
 /*
  * The leaf data grows from end-to-front in the node.
  * this returns the address of the start of the last item,
@@ -221,6 +332,7 @@ static int check_leaf(struct btrfs_root *root, struct btrfs_path *path,
 
 		parent_slot = path->slots[level + 1];
 		parent_key = &parent->ptrs[parent_slot].key;
+
 		BUG_ON(memcmp(parent_key, &leaf->items[0].key,
 		       sizeof(struct btrfs_disk_key)));
 		BUG_ON(btrfs_node_blockptr(parent, parent_slot) !=
@@ -643,7 +755,7 @@ static int push_nodes_for_insert(struct btrfs_trans_handle *trans,
  * readahead one full node of leaves
  */
 static void reada_for_search(struct btrfs_root *root, struct btrfs_path *path,
-			     int slot)
+			     int level, int slot)
 {
 	struct btrfs_node *node;
 	int i;
@@ -659,10 +771,13 @@ static void reada_for_search(struct btrfs_root *root, struct btrfs_path *path,
 	unsigned long gang[8];
 	struct buffer_head *bh;
 
-	if (!path->nodes[1])
+	if (level == 0)
+		return;
+
+	if (!path->nodes[level])
 		return;
 
-	node = btrfs_buffer_node(path->nodes[1]);
+	node = btrfs_buffer_node(path->nodes[level]);
 	search = btrfs_node_blockptr(node, slot);
 	bh = btrfs_find_tree_block(root, search);
 	if (bh) {
@@ -690,7 +805,7 @@ static void reada_for_search(struct btrfs_root *root, struct btrfs_path *path,
 		for (i = 0; i < ret; i++) {
 			blocknr = gang[i];
 			clear_radix_bit(&found, blocknr);
-			if (nread > 64)
+			if (nread > 32)
 				continue;
 			if (direction > 0 && cluster_start <= blocknr &&
 			    cluster_start + 8 > blocknr) {
@@ -726,7 +841,6 @@ int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root
 	struct buffer_head *b;
 	struct buffer_head *cow_buf;
 	struct btrfs_node *c;
-	struct btrfs_root_item *root_item = &root->root_item;
 	u64 blocknr;
 	int slot;
 	int ret;
@@ -734,11 +848,8 @@ int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root
 	int should_reada = p->reada;
 	u8 lowest_level = 0;
 
-	if (btrfs_root_refs(root_item) == 0 && root->ref_cows) {
-		lowest_level = root_item->drop_level;
-		WARN_ON(ins_len || cow);
-	}
-
+	lowest_level = p->lowest_level;
+	WARN_ON(lowest_level && ins_len);
 	WARN_ON(p->nodes[0] != NULL);
 	WARN_ON(!mutex_is_locked(&root->fs_info->fs_mutex));
 again:
@@ -798,8 +909,8 @@ int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root
 			if (level == lowest_level)
 				break;
 			blocknr = btrfs_node_blockptr(c, slot);
-			if (level == 1 && should_reada)
-				reada_for_search(root, p, slot);
+			if (should_reada)
+				reada_for_search(root, p, level, slot);
 			b = read_tree_block(root, btrfs_node_blockptr(c, slot));
 
 		} else {
@@ -960,7 +1071,7 @@ static int insert_new_root(struct btrfs_trans_handle *trans, struct btrfs_root
 	BUG_ON(path->nodes[level]);
 	BUG_ON(path->nodes[level-1] != root->node);
 
-	t = btrfs_alloc_free_block(trans, root, root->node->b_blocknr);
+	t = btrfs_alloc_free_block(trans, root, root->node->b_blocknr, 0);
 	if (IS_ERR(t))
 		return PTR_ERR(t);
 	c = btrfs_buffer_node(t);
@@ -1070,7 +1181,7 @@ static int split_node(struct btrfs_trans_handle *trans, struct btrfs_root
 	}
 
 	c_nritems = btrfs_header_nritems(&c->header);
-	split_buffer = btrfs_alloc_free_block(trans, root, t->b_blocknr);
+	split_buffer = btrfs_alloc_free_block(trans, root, t->b_blocknr, 0);
 	if (IS_ERR(split_buffer))
 		return PTR_ERR(split_buffer);
 
@@ -1461,7 +1572,7 @@ static int split_leaf(struct btrfs_trans_handle *trans, struct btrfs_root
 	nritems = btrfs_header_nritems(&l->header);
 	mid = (nritems + 1)/ 2;
 
-	right_buffer = btrfs_alloc_free_block(trans, root, l_buf->b_blocknr);
+	right_buffer = btrfs_alloc_free_block(trans, root, l_buf->b_blocknr, 0);
 	if (IS_ERR(right_buffer))
 		return PTR_ERR(right_buffer);
 
@@ -1560,7 +1671,7 @@ static int split_leaf(struct btrfs_trans_handle *trans, struct btrfs_root
 
 	if (!double_split)
 		return ret;
-	right_buffer = btrfs_alloc_free_block(trans, root, l_buf->b_blocknr);
+	right_buffer = btrfs_alloc_free_block(trans, root, l_buf->b_blocknr, 0);
 	if (IS_ERR(right_buffer))
 		return PTR_ERR(right_buffer);
 
@@ -1988,8 +2099,8 @@ int btrfs_next_leaf(struct btrfs_root *root, struct btrfs_path *path)
 		blocknr = btrfs_node_blockptr(c_node, slot);
 		if (next)
 			btrfs_block_release(root, next);
-		if (level == 1 && path->reada)
-			reada_for_search(root, path, slot);
+		if (path->reada)
+			reada_for_search(root, path, level, slot);
 		next = read_tree_block(root, blocknr);
 		break;
 	}
@@ -2002,8 +2113,8 @@ int btrfs_next_leaf(struct btrfs_root *root, struct btrfs_path *path)
 		path->slots[level] = 0;
 		if (!level)
 			break;
-		if (level == 1 && path->reada)
-			reada_for_search(root, path, slot);
+		if (path->reada)
+			reada_for_search(root, path, level, slot);
 		next = read_tree_block(root,
 		       btrfs_node_blockptr(btrfs_buffer_node(next), 0));
 	}
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index c5a18d5d7f7c244b73795e7c6567529f014ff654..42aa20301bc9b27e571413788cd6fc5d4ef5b469 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -178,6 +178,7 @@ struct btrfs_path {
 	struct buffer_head *nodes[BTRFS_MAX_LEVEL];
 	int slots[BTRFS_MAX_LEVEL];
 	int reada;
+	int lowest_level;
 };
 
 /*
@@ -338,6 +339,9 @@ struct btrfs_root {
 	u64 highest_inode;
 	u64 last_inode_alloc;
 	int ref_cows;
+	struct btrfs_key defrag_progress;
+	int defrag_running;
+	int defrag_level;
 };
 
 /* the lower bits in the key flags defines the item type */
@@ -1031,10 +1035,11 @@ struct btrfs_block_group_cache *btrfs_find_block_group(struct btrfs_root *root,
 int btrfs_inc_root_ref(struct btrfs_trans_handle *trans,
 		       struct btrfs_root *root);
 struct buffer_head *btrfs_alloc_free_block(struct btrfs_trans_handle *trans,
-					    struct btrfs_root *root, u64 hint);
+					    struct btrfs_root *root, u64 hint,
+					    u64 empty_size);
 int btrfs_alloc_extent(struct btrfs_trans_handle *trans,
 		       struct btrfs_root *root, u64 owner,
-		       u64 num_blocks, u64 search_start,
+		       u64 num_blocks, u64 empty_size, u64 search_start,
 		       u64 search_end, struct btrfs_key *ins, int data);
 int btrfs_inc_ref(struct btrfs_trans_handle *trans, struct btrfs_root *root,
 		  struct buffer_head *buf);
@@ -1051,6 +1056,10 @@ int btrfs_write_dirty_block_groups(struct btrfs_trans_handle *trans,
 int btrfs_free_block_groups(struct btrfs_fs_info *info);
 int btrfs_read_block_groups(struct btrfs_root *root);
 /* ctree.c */
+int btrfs_cow_block(struct btrfs_trans_handle *trans, struct btrfs_root
+			   *root, struct buffer_head *buf, struct buffer_head
+			   *parent, int parent_slot, struct buffer_head
+			   **cow_ret);
 int btrfs_extend_item(struct btrfs_trans_handle *trans, struct btrfs_root
 		      *root, struct btrfs_path *path, u32 data_size);
 int btrfs_truncate_item(struct btrfs_trans_handle *trans,
@@ -1060,6 +1069,9 @@ int btrfs_truncate_item(struct btrfs_trans_handle *trans,
 int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root
 		      *root, struct btrfs_key *key, struct btrfs_path *p, int
 		      ins_len, int cow);
+int btrfs_realloc_node(struct btrfs_trans_handle *trans,
+		       struct btrfs_root *root, struct buffer_head *parent,
+		       int cache_only);
 void btrfs_release_path(struct btrfs_root *root, struct btrfs_path *p);
 struct btrfs_path *btrfs_alloc_path(void);
 void btrfs_free_path(struct btrfs_path *p);
@@ -1171,4 +1183,7 @@ extern struct file_operations btrfs_file_operations;
 int btrfs_drop_extents(struct btrfs_trans_handle *trans,
 		       struct btrfs_root *root, struct inode *inode,
 		       u64 start, u64 end, u64 *hint_block);
+/* tree-defrag.c */
+int btrfs_defrag_leaves(struct btrfs_trans_handle *trans,
+			struct btrfs_root *root, int cache_only);
 #endif
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 60db85bc4ba8d70a11267f22453a484bd9758bb4..c948416fea3aca8f9673ef98eca60e3c85a77eb1 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -273,7 +273,9 @@ int clean_tree_block(struct btrfs_trans_handle *trans, struct btrfs_root *root,
 		     struct buffer_head *buf)
 {
 	WARN_ON(atomic_read(&buf->b_count) == 0);
+	lock_buffer(buf);
 	clear_buffer_dirty(buf);
+	unlock_buffer(buf);
 	return 0;
 }
 
@@ -294,6 +296,9 @@ static int __setup_root(int blocksize,
 	root->last_inode_alloc = 0;
 	memset(&root->root_key, 0, sizeof(root->root_key));
 	memset(&root->root_item, 0, sizeof(root->root_item));
+	memset(&root->defrag_progress, 0, sizeof(root->defrag_progress));
+	root->defrag_running = 0;
+	root->defrag_level = 0;
 	root->root_key.objectid = objectid;
 	return 0;
 }
@@ -585,6 +590,7 @@ int close_ctree(struct btrfs_root *root)
 	fs_info->closing = 1;
 	btrfs_transaction_flush_work(root);
 	mutex_lock(&fs_info->fs_mutex);
+	btrfs_defrag_dirty_roots(root->fs_info);
 	trans = btrfs_start_transaction(root, 1);
 	ret = btrfs_commit_transaction(trans, root);
 	/* run commit again to  drop the original snapshot */
@@ -616,7 +622,9 @@ void btrfs_mark_buffer_dirty(struct buffer_head *bh)
 {
 	struct btrfs_root *root = BTRFS_I(bh->b_page->mapping->host)->root;
 	u64 transid = btrfs_header_generation(btrfs_buffer_header(bh));
+
 	WARN_ON(!atomic_read(&bh->b_count));
+
 	if (transid != root->fs_info->generation) {
 		printk(KERN_CRIT "transid mismatch buffer %llu, found %Lu running %Lu\n",
 			(unsigned long long)bh->b_blocknr,
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 5d4d5d8db8efa3f7cc3a9e23bc98affee85aa215..26b8d340649128d232ab3ba41e7a2f76a0905a79 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -23,7 +23,8 @@
 #include "transaction.h"
 
 static int find_free_extent(struct btrfs_trans_handle *trans, struct btrfs_root
-			    *orig_root, u64 num_blocks, u64 search_start,
+			    *orig_root, u64 num_blocks, u64 empty_size,
+			    u64 search_start,
 			    u64 search_end, u64 hint_block,
 			    struct btrfs_key *ins, u64 exclude_start,
 			    u64 exclude_nr, int data);
@@ -379,7 +380,7 @@ int btrfs_inc_extent_ref(struct btrfs_trans_handle *trans,
 	path = btrfs_alloc_path();
 	if (!path)
 		return -ENOMEM;
-	ret = find_free_extent(trans, root->fs_info->extent_root, 0, 0,
+	ret = find_free_extent(trans, root->fs_info->extent_root, 0, 0, 0,
 			       (u64)-1, 0, &ins, 0, 0, 0);
 	if (ret) {
 		btrfs_free_path(path);
@@ -533,7 +534,7 @@ static int write_one_cache_group(struct btrfs_trans_handle *trans,
 	struct btrfs_block_group_item *bi;
 	struct btrfs_key ins;
 
-	ret = find_free_extent(trans, extent_root, 0, 0, (u64)-1, 0, &ins,
+	ret = find_free_extent(trans, extent_root, 0, 0, 0, (u64)-1, 0, &ins,
 			       0, 0, 0);
 	/* FIXME, set bit to recalc cache groups on next mount */
 	if (ret)
@@ -708,6 +709,7 @@ static int update_block_group(struct btrfs_trans_handle *trans,
 static int try_remove_page(struct address_space *mapping, unsigned long index)
 {
 	int ret;
+	return 0;
 	ret = invalidate_mapping_pages(mapping, index, index);
 	return ret;
 }
@@ -866,7 +868,7 @@ static int __free_extent(struct btrfs_trans_handle *trans, struct btrfs_root
 	if (!path)
 		return -ENOMEM;
 
-	ret = find_free_extent(trans, root, 0, 0, (u64)-1, 0, &ins, 0, 0, 0);
+	ret = find_free_extent(trans, root, 0, 0, 0, (u64)-1, 0, &ins, 0, 0, 0);
 	if (ret) {
 		btrfs_free_path(path);
 		return ret;
@@ -983,8 +985,8 @@ int btrfs_free_extent(struct btrfs_trans_handle *trans, struct btrfs_root
  * Any available blocks before search_start are skipped.
  */
 static int find_free_extent(struct btrfs_trans_handle *trans, struct btrfs_root
-			    *orig_root, u64 num_blocks, u64 search_start, u64
-			    search_end, u64 hint_block,
+			    *orig_root, u64 num_blocks, u64 empty_size,
+			    u64 search_start, u64 search_end, u64 hint_block,
 			    struct btrfs_key *ins, u64 exclude_start,
 			    u64 exclude_nr, int data)
 {
@@ -1042,6 +1044,7 @@ static int find_free_extent(struct btrfs_trans_handle *trans, struct btrfs_root
 						     data, 1);
 	}
 
+	total_needed += empty_size;
 	path = btrfs_alloc_path();
 
 check_failed:
@@ -1157,9 +1160,11 @@ static int find_free_extent(struct btrfs_trans_handle *trans, struct btrfs_root
 			goto error;
 		}
 		search_start = orig_search_start;
-		if (wrapped)
+		if (wrapped) {
+			if (!full_scan)
+				total_needed -= empty_size;
 			full_scan = 1;
-		else
+		} else
 			wrapped = 1;
 		goto new_group;
 	}
@@ -1238,9 +1243,11 @@ static int find_free_extent(struct btrfs_trans_handle *trans, struct btrfs_root
 			ret = -ENOSPC;
 			goto error;
 		}
-		if (wrapped)
+		if (wrapped) {
+			if (!full_scan)
+				total_needed -= empty_size;
 			full_scan = 1;
-		else
+		} else
 			wrapped = 1;
 	}
 	block_group = btrfs_lookup_block_group(info, search_start);
@@ -1264,7 +1271,7 @@ static int find_free_extent(struct btrfs_trans_handle *trans, struct btrfs_root
  */
 int btrfs_alloc_extent(struct btrfs_trans_handle *trans,
 		       struct btrfs_root *root, u64 owner,
-		       u64 num_blocks, u64 hint_block,
+		       u64 num_blocks, u64 empty_size, u64 hint_block,
 		       u64 search_end, struct btrfs_key *ins, int data)
 {
 	int ret;
@@ -1303,7 +1310,7 @@ int btrfs_alloc_extent(struct btrfs_trans_handle *trans,
 	 * in the correct block group.
 	 */
 	if (data) {
-		ret = find_free_extent(trans, root, 0, 0,
+		ret = find_free_extent(trans, root, 0, 0, 0,
 				       search_end, 0, &prealloc_key, 0, 0, 0);
 		BUG_ON(ret);
 		if (ret)
@@ -1313,8 +1320,8 @@ int btrfs_alloc_extent(struct btrfs_trans_handle *trans,
 	}
 
 	/* do the real allocation */
-	ret = find_free_extent(trans, root, num_blocks, search_start,
-			       search_end, hint_block, ins,
+	ret = find_free_extent(trans, root, num_blocks, empty_size,
+			       search_start, search_end, hint_block, ins,
 			       exclude_start, exclude_nr, data);
 	BUG_ON(ret);
 	if (ret)
@@ -1333,7 +1340,7 @@ int btrfs_alloc_extent(struct btrfs_trans_handle *trans,
 		exclude_start = ins->objectid;
 		exclude_nr = ins->offset;
 		hint_block = exclude_start + exclude_nr;
-		ret = find_free_extent(trans, root, 0, search_start,
+		ret = find_free_extent(trans, root, 0, 0, search_start,
 				       search_end, hint_block,
 				       &prealloc_key, exclude_start,
 				       exclude_nr, 0);
@@ -1368,14 +1375,16 @@ int btrfs_alloc_extent(struct btrfs_trans_handle *trans,
  * returns the tree buffer or NULL.
  */
 struct buffer_head *btrfs_alloc_free_block(struct btrfs_trans_handle *trans,
-					   struct btrfs_root *root, u64 hint)
+					   struct btrfs_root *root, u64 hint,
+					   u64 empty_size)
 {
 	struct btrfs_key ins;
 	int ret;
 	struct buffer_head *buf;
 
 	ret = btrfs_alloc_extent(trans, root, root->root_key.objectid,
-				 1, hint, (unsigned long)-1, &ins, 0);
+				 1, empty_size, hint,
+				 (unsigned long)-1, &ins, 0);
 	if (ret) {
 		BUG_ON(ret > 0);
 		return ERR_PTR(ret);
@@ -1385,6 +1394,7 @@ struct buffer_head *btrfs_alloc_free_block(struct btrfs_trans_handle *trans,
 		btrfs_free_extent(trans, root, ins.objectid, 1, 0);
 		return ERR_PTR(-ENOMEM);
 	}
+	WARN_ON(buffer_dirty(buf));
 	set_buffer_uptodate(buf);
 	set_buffer_checked(buf);
 	set_radix_bit(&trans->transaction->dirty_pages, buf->b_page->index);
@@ -1591,13 +1601,15 @@ int btrfs_drop_snapshot(struct btrfs_trans_handle *trans, struct btrfs_root
 		struct btrfs_key key;
 		struct btrfs_disk_key *found_key;
 		struct btrfs_node *node;
+
 		btrfs_disk_key_to_cpu(&key, &root_item->drop_progress);
+		level = root_item->drop_level;
+		path->lowest_level = level;
 		wret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
-		if (ret < 0) {
+		if (wret < 0) {
 			ret = wret;
 			goto out;
 		}
-		level = root_item->drop_level;
 		node = btrfs_buffer_node(path->nodes[level]);
 		found_key = &node->ptrs[path->slots[level]].key;
 		WARN_ON(memcmp(found_key, &root_item->drop_progress,
@@ -1617,8 +1629,6 @@ int btrfs_drop_snapshot(struct btrfs_trans_handle *trans, struct btrfs_root
 			ret = wret;
 		num_walks++;
 		if (num_walks > 10) {
-			struct btrfs_key key;
-			btrfs_disk_key_to_cpu(&key, &root_item->drop_progress);
 			ret = -EAGAIN;
 			get_bh(root->node);
 			break;
@@ -1627,6 +1637,7 @@ int btrfs_drop_snapshot(struct btrfs_trans_handle *trans, struct btrfs_root
 	for (i = 0; i <= orig_level; i++) {
 		if (path->nodes[i]) {
 			btrfs_block_release(root, path->nodes[i]);
+			path->nodes[i] = 0;
 		}
 	}
 out:
diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index 1fe38fe841502d3a1e40394b6f559f186759968f..00b118a2db6925ba0810a461bd484dfa7a855391 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -512,7 +512,7 @@ static int prepare_pages(struct btrfs_root *root,
 	if (isize >= PAGE_CACHE_SIZE || pos + write_bytes < inode->i_size ||
 	    pos + write_bytes - start_pos > BTRFS_MAX_INLINE_DATA_SIZE(root)) {
 		err = btrfs_alloc_extent(trans, root, inode->i_ino,
-					 num_blocks, hint_block, (u64)-1,
+					 num_blocks, 0, hint_block, (u64)-1,
 					 &ins, 1);
 		if (err)
 			goto failed_truncate;
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 3889032fc449762ec2cfa11307390b591a774919..12aa043b9f6f2e7fad6eaeb64dde8ae6d683d5f4 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -554,7 +554,7 @@ static int btrfs_truncate_page(struct address_space *mapping, loff_t from)
 				 &alloc_hint);
 	if (ret)
 		goto out;
-	ret = btrfs_alloc_extent(trans, root, inode->i_ino, 1,
+	ret = btrfs_alloc_extent(trans, root, inode->i_ino, 1, 0,
 				 alloc_hint, (u64)-1, &ins, 1);
 	if (ret)
 		goto out;
@@ -1360,7 +1360,7 @@ static int btrfs_get_block_lock(struct inode *inode, sector_t iblock,
 	if (create & BTRFS_GET_BLOCK_CREATE) {
 		struct btrfs_key ins;
 		ret = btrfs_alloc_extent(trans, root, inode->i_ino,
-					 1, alloc_hint, (u64)-1,
+					 1, 0, alloc_hint, (u64)-1,
 					 &ins, 1);
 		if (ret) {
 			err = ret;
@@ -1998,7 +1998,7 @@ static int create_subvol(struct btrfs_root *root, char *name, int namelen)
 	trans = btrfs_start_transaction(root, 1);
 	BUG_ON(!trans);
 
-	subvol = btrfs_alloc_free_block(trans, root, 0);
+	subvol = btrfs_alloc_free_block(trans, root, 0, 0);
 	if (IS_ERR(subvol))
 		return PTR_ERR(subvol);
 	leaf = btrfs_buffer_leaf(subvol);
@@ -2159,7 +2159,9 @@ int btrfs_ioctl(struct inode *inode, struct file *filp, unsigned int
 {
 	struct btrfs_root *root = BTRFS_I(inode)->root;
 	struct btrfs_ioctl_vol_args vol_args;
+	struct btrfs_trans_handle *trans;
 	int ret = 0;
+	int err;
 	struct btrfs_dir_item *di;
 	int namelen;
 	struct btrfs_path *path;
@@ -2196,6 +2198,31 @@ int btrfs_ioctl(struct inode *inode, struct file *filp, unsigned int
 		else
 			ret = create_snapshot(root, vol_args.name, namelen);
 		break;
+
+	case BTRFS_IOC_DEFRAG:
+		mutex_lock(&root->fs_info->fs_mutex);
+		trans = btrfs_start_transaction(root, 1);
+		memset(&root->defrag_progress, 0,
+		       sizeof(root->defrag_progress));
+		while (1) {
+			root->defrag_running = 1;
+			err = btrfs_defrag_leaves(trans, root, 0);
+
+			btrfs_end_transaction(trans, root);
+			mutex_unlock(&root->fs_info->fs_mutex);
+
+			btrfs_btree_balance_dirty(root);
+
+			mutex_lock(&root->fs_info->fs_mutex);
+			trans = btrfs_start_transaction(root, 1);
+			if (err != -EAGAIN)
+				break;
+		}
+		root->defrag_running = 0;
+		btrfs_end_transaction(trans, root);
+		mutex_unlock(&root->fs_info->fs_mutex);
+		ret = 0;
+		break;
 	default:
 		return -ENOTTY;
 	}
diff --git a/fs/btrfs/ioctl.h b/fs/btrfs/ioctl.h
index 23bed48c51a7c28bcf5cbec03e7524bb4f6f4e71..8bc47dec2865eadfcfe36721c64b0ea59e99de68 100644
--- a/fs/btrfs/ioctl.h
+++ b/fs/btrfs/ioctl.h
@@ -28,6 +28,6 @@ struct btrfs_ioctl_vol_args {
 
 #define BTRFS_IOC_SNAP_CREATE _IOW(BTRFS_IOCTL_MAGIC, 1, \
 				   struct btrfs_ioctl_vol_args)
-#define BTRFS_IOC_ADD_DISK _IOW(BTRFS_IOCTL_MAGIC, 2, \
+#define BTRFS_IOC_DEFRAG _IOW(BTRFS_IOCTL_MAGIC, 2, \
 				   struct btrfs_ioctl_vol_args)
 #endif
diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index 498626470a049d57fa9cd269bb9e697ea852e8b4..338a7199363b12875868414a7336c1f25bd7449d 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -29,6 +29,7 @@ extern struct kmem_cache *btrfs_transaction_cachep;
 static struct workqueue_struct *trans_wq;
 
 #define BTRFS_ROOT_TRANS_TAG 0
+#define BTRFS_ROOT_DEFRAG_TAG 1
 
 static void put_transaction(struct btrfs_transaction *transaction)
 {
@@ -69,35 +70,41 @@ static int join_transaction(struct btrfs_root *root)
 	return 0;
 }
 
+static int record_root_in_trans(struct btrfs_root *root)
+{
+	u64 running_trans_id = root->fs_info->running_transaction->transid;
+	if (root->ref_cows && root->last_trans < running_trans_id) {
+		WARN_ON(root == root->fs_info->extent_root);
+		if (root->root_item.refs != 0) {
+			radix_tree_tag_set(&root->fs_info->fs_roots_radix,
+				   (unsigned long)root->root_key.objectid,
+				   BTRFS_ROOT_TRANS_TAG);
+			radix_tree_tag_set(&root->fs_info->fs_roots_radix,
+				   (unsigned long)root->root_key.objectid,
+				   BTRFS_ROOT_DEFRAG_TAG);
+			root->commit_root = root->node;
+			get_bh(root->node);
+		} else {
+			WARN_ON(1);
+		}
+		root->last_trans = running_trans_id;
+	}
+	return 0;
+}
+
 struct btrfs_trans_handle *btrfs_start_transaction(struct btrfs_root *root,
 						   int num_blocks)
 {
 	struct btrfs_trans_handle *h =
 		kmem_cache_alloc(btrfs_trans_handle_cachep, GFP_NOFS);
 	int ret;
-	u64 running_trans_id;
 
 	mutex_lock(&root->fs_info->trans_mutex);
 	ret = join_transaction(root);
 	BUG_ON(ret);
-	running_trans_id = root->fs_info->running_transaction->transid;
 
-	if (root != root->fs_info->tree_root && root->last_trans <
-	    running_trans_id) {
-		WARN_ON(root == root->fs_info->extent_root);
-		WARN_ON(root->ref_cows != 1);
-		if (root->root_item.refs != 0) {
-			radix_tree_tag_set(&root->fs_info->fs_roots_radix,
-					   (unsigned long)root->root_key.objectid,
-					   BTRFS_ROOT_TRANS_TAG);
-			root->commit_root = root->node;
-			get_bh(root->node);
-		} else {
-			WARN_ON(1);
-		}
-	}
-	root->last_trans = running_trans_id;
-	h->transid = running_trans_id;
+	record_root_in_trans(root);
+	h->transid = root->fs_info->running_transaction->transid;
 	h->transaction = root->fs_info->running_transaction;
 	h->blocks_reserved = num_blocks;
 	h->blocks_used = 0;
@@ -155,6 +162,15 @@ int btrfs_write_and_wait_transaction(struct btrfs_trans_handle *trans,
 					      gang[i]);
 			if (!page)
 				continue;
+			if (PageWriteback(page)) {
+				if (PageDirty(page))
+					wait_on_page_writeback(page);
+				else {
+					unlock_page(page);
+					page_cache_release(page);
+					continue;
+				}
+			}
 			err = write_one_page(page, 0);
 			if (err)
 				werr = err;
@@ -299,6 +315,58 @@ static int add_dirty_roots(struct btrfs_trans_handle *trans,
 	return err;
 }
 
+int btrfs_defrag_dirty_roots(struct btrfs_fs_info *info)
+{
+	struct btrfs_root *gang[1];
+	struct btrfs_root *root;
+	struct btrfs_root *tree_root = info->tree_root;
+	struct btrfs_trans_handle *trans;
+	int i;
+	int ret;
+	int err = 0;
+	u64 last = 0;
+
+	trans = btrfs_start_transaction(tree_root, 1);
+	while(1) {
+		ret = radix_tree_gang_lookup_tag(&info->fs_roots_radix,
+						 (void **)gang, last,
+						 ARRAY_SIZE(gang),
+						 BTRFS_ROOT_DEFRAG_TAG);
+		if (ret == 0)
+			break;
+		for (i = 0; i < ret; i++) {
+			root = gang[i];
+			last = root->root_key.objectid + 1;
+			radix_tree_tag_clear(&info->fs_roots_radix,
+				     (unsigned long)root->root_key.objectid,
+				     BTRFS_ROOT_DEFRAG_TAG);
+			if (root->defrag_running)
+				continue;
+
+			while (1) {
+				mutex_lock(&root->fs_info->trans_mutex);
+				record_root_in_trans(root);
+				mutex_unlock(&root->fs_info->trans_mutex);
+
+				root->defrag_running = 1;
+				err = btrfs_defrag_leaves(trans, root, 1);
+				btrfs_end_transaction(trans, tree_root);
+				mutex_unlock(&info->fs_mutex);
+
+				btrfs_btree_balance_dirty(root);
+
+				mutex_lock(&info->fs_mutex);
+				trans = btrfs_start_transaction(tree_root, 1);
+				if (err != -EAGAIN)
+					break;
+			}
+			root->defrag_running = 0;
+		}
+	}
+	btrfs_end_transaction(trans, tree_root);
+	return err;
+}
+
 static int drop_dirty_roots(struct btrfs_root *tree_root,
 			    struct list_head *list)
 {
@@ -475,6 +543,7 @@ void btrfs_transaction_cleaner(struct work_struct *work)
 		goto out;
 	}
 	mutex_unlock(&root->fs_info->trans_mutex);
+	btrfs_defrag_dirty_roots(root->fs_info);
 	trans = btrfs_start_transaction(root, 1);
 	ret = btrfs_commit_transaction(trans, root);
 out:
diff --git a/fs/btrfs/transaction.h b/fs/btrfs/transaction.h
index ebf44f3e1118c0477b8311b23342885540fa79b9..8b2714e65562985ee64f01fb11c11e5e4eb8ea51 100644
--- a/fs/btrfs/transaction.h
+++ b/fs/btrfs/transaction.h
@@ -70,5 +70,6 @@ void btrfs_transaction_queue_work(struct btrfs_root *root, int delay);
 void btrfs_init_transaction_sys(void);
 void btrfs_exit_transaction_sys(void);
 int btrfs_add_dead_root(struct btrfs_root *root, struct list_head *dead_list);
+int btrfs_defrag_dirty_roots(struct btrfs_fs_info *info);
 
 #endif
diff --git a/fs/btrfs/tree-defrag.c b/fs/btrfs/tree-defrag.c
new file mode 100644
index 0000000000000000000000000000000000000000..15d0a486fb593a706f3d4e4d41a85c8d5f34562b
--- /dev/null
+++ b/fs/btrfs/tree-defrag.c
@@ -0,0 +1,222 @@
+/*
+ * Copyright (C) 2007 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 <linux/sched.h>
+#include "ctree.h"
+#include "disk-io.h"
+#include "print-tree.h"
+#include "transaction.h"
+
+static void reada_defrag(struct btrfs_root *root,
+			 struct btrfs_node *node)
+{
+	int i;
+	u32 nritems;
+	u64 blocknr;
+	int ret;
+
+	nritems = btrfs_header_nritems(&node->header);
+	for (i = 0; i < nritems; i++) {
+		blocknr = btrfs_node_blockptr(node, i);
+		ret = readahead_tree_block(root, blocknr);
+		if (ret)
+			break;
+	}
+}
+
+static int defrag_walk_down(struct btrfs_trans_handle *trans,
+			    struct btrfs_root *root,
+			    struct btrfs_path *path, int *level,
+			    int cache_only)
+{
+	struct buffer_head *next;
+	struct buffer_head *cur;
+	u64 blocknr;
+	int ret = 0;
+
+	WARN_ON(*level < 0);
+	WARN_ON(*level >= BTRFS_MAX_LEVEL);
+
+	while(*level > 0) {
+		WARN_ON(*level < 0);
+		WARN_ON(*level >= BTRFS_MAX_LEVEL);
+		cur = path->nodes[*level];
+
+		if (!cache_only && *level > 1 && path->slots[*level] == 0)
+			reada_defrag(root, btrfs_buffer_node(cur));
+
+		if (btrfs_header_level(btrfs_buffer_header(cur)) != *level)
+			WARN_ON(1);
+
+		if (path->slots[*level] >=
+		    btrfs_header_nritems(btrfs_buffer_header(cur)))
+			break;
+
+		if (*level == 1) {
+			ret = btrfs_realloc_node(trans, root,
+						 path->nodes[*level],
+						 cache_only);
+			break;
+		}
+		blocknr = btrfs_node_blockptr(btrfs_buffer_node(cur),
+					      path->slots[*level]);
+
+		if (cache_only) {
+			next = btrfs_find_tree_block(root, blocknr);
+			if (!next || !buffer_uptodate(next) ||
+			   buffer_locked(next)) {
+				brelse(next);
+				path->slots[*level]++;
+				continue;
+			}
+		} else {
+			next = read_tree_block(root, blocknr);
+		}
+		ret = btrfs_cow_block(trans, root, next, path->nodes[*level],
+				      path->slots[*level], &next);
+		BUG_ON(ret);
+		ret = btrfs_realloc_node(trans, root, next, cache_only);
+		BUG_ON(ret);
+		WARN_ON(*level <= 0);
+		if (path->nodes[*level-1])
+			btrfs_block_release(root, path->nodes[*level-1]);
+		path->nodes[*level-1] = next;
+		*level = btrfs_header_level(btrfs_buffer_header(next));
+		path->slots[*level] = 0;
+	}
+	WARN_ON(*level < 0);
+	WARN_ON(*level >= BTRFS_MAX_LEVEL);
+	btrfs_block_release(root, path->nodes[*level]);
+	path->nodes[*level] = NULL;
+	*level += 1;
+	WARN_ON(ret);
+	return 0;
+}
+
+static int defrag_walk_up(struct btrfs_trans_handle *trans,
+			  struct btrfs_root *root,
+			  struct btrfs_path *path, int *level,
+			  int cache_only)
+{
+	int i;
+	int slot;
+	struct btrfs_node *node;
+
+	for(i = *level; i < BTRFS_MAX_LEVEL - 1 && path->nodes[i]; i++) {
+		slot = path->slots[i];
+		if (slot < btrfs_header_nritems(
+		    btrfs_buffer_header(path->nodes[i])) - 1) {
+			path->slots[i]++;
+			*level = i;
+			node = btrfs_buffer_node(path->nodes[i]);
+			WARN_ON(i == 0);
+			btrfs_disk_key_to_cpu(&root->defrag_progress,
+					      &node->ptrs[path->slots[i]].key);
+			root->defrag_level = i;
+			return 0;
+		} else {
+			btrfs_block_release(root, path->nodes[*level]);
+			path->nodes[*level] = NULL;
+			*level = i + 1;
+		}
+	}
+	return 1;
+}
+
+int btrfs_defrag_leaves(struct btrfs_trans_handle *trans,
+			struct btrfs_root *root, int cache_only)
+{
+	struct btrfs_path *path = NULL;
+	struct buffer_head *tmp;
+	int ret = 0;
+	int wret;
+	int level;
+	int orig_level;
+	int i;
+	int num_runs = 0;
+
+	if (root->ref_cows == 0) {
+		goto out;
+	}
+	path = btrfs_alloc_path();
+	if (!path)
+		return -ENOMEM;
+
+	level = btrfs_header_level(btrfs_buffer_header(root->node));
+	orig_level = level;
+	if (level == 0) {
+		goto out;
+	}
+	if (root->defrag_progress.objectid == 0) {
+		get_bh(root->node);
+		ret = btrfs_cow_block(trans, root, root->node, NULL, 0, &tmp);
+		BUG_ON(ret);
+		ret = btrfs_realloc_node(trans, root, root->node, cache_only);
+		BUG_ON(ret);
+		path->nodes[level] = root->node;
+		path->slots[level] = 0;
+	} else {
+		level = root->defrag_level;
+		path->lowest_level = level;
+		wret = btrfs_search_slot(trans, root, &root->defrag_progress,
+					 path, 0, 1);
+
+		if (wret < 0) {
+			ret = wret;
+			goto out;
+		}
+		while(level > 0 && !path->nodes[level])
+			level--;
+		if (!path->nodes[level]) {
+			ret = 0;
+			goto out;
+		}
+	}
+
+	while(1) {
+		wret = defrag_walk_down(trans, root, path, &level, cache_only);
+		if (wret > 0)
+			break;
+		if (wret < 0)
+			ret = wret;
+
+		wret = defrag_walk_up(trans, root, path, &level, cache_only);
+		if (wret > 0)
+			break;
+		if (wret < 0)
+			ret = wret;
+		if (num_runs++ > 8) {
+			ret = -EAGAIN;
+			break;
+		}
+	}
+	for (i = 0; i <= orig_level; i++) {
+		if (path->nodes[i]) {
+			btrfs_block_release(root, path->nodes[i]);
+			path->nodes[i] = 0;
+		}
+	}
+out:
+	if (path)
+		btrfs_free_path(path);
+	if (ret != -EAGAIN) {
+		memset(&root->defrag_progress, 0,
+		       sizeof(root->defrag_progress));
+	}
+	return ret;
+}