diff --git a/fs/btrfs/mkfs.c b/fs/btrfs/mkfs.c
index fc19233..dd14ed4 100644
--- a/fs/btrfs/mkfs.c
+++ b/fs/btrfs/mkfs.c
@@ -10,6 +10,120 @@
 #include "ctree.h"
 #include "disk-io.h"
 
+int mkfs(int fd, u64 num_blocks, u16 blocksize)
+{
+	struct btrfs_super_block super;
+	struct btrfs_leaf empty_leaf;
+	struct btrfs_root_item root_item;
+	struct btrfs_item item;
+	struct btrfs_extent_item extent_item;
+	char *block;
+	int ret;
+	u16 itemoff;
+
+	btrfs_set_super_blocknr(&super, 16);
+	btrfs_set_super_root(&super, 17);
+	strcpy((char *)(&super.magic), BTRFS_MAGIC);
+	btrfs_set_super_blocksize(&super, blocksize);
+	btrfs_set_super_total_blocks(&super, num_blocks);
+	btrfs_set_super_blocks_used(&super, 0);
+
+	block = malloc(blocksize);
+	memset(block, 0, blocksize);
+	BUG_ON(sizeof(super) > blocksize);
+	memcpy(block, &super, sizeof(super));
+	ret = pwrite(fd, block, blocksize, BTRFS_SUPER_INFO_OFFSET(blocksize));
+	BUG_ON(ret != blocksize);
+
+	/* create the tree of root objects */
+	memset(&empty_leaf, 0, sizeof(empty_leaf));
+	btrfs_set_header_parentid(&empty_leaf.header, BTRFS_ROOT_TREE_OBJECTID);
+	btrfs_set_header_blocknr(&empty_leaf.header, 17);
+	btrfs_set_header_nritems(&empty_leaf.header, 2);
+
+	/* create the items for the root tree */
+	btrfs_set_root_blocknr(&root_item, 18);
+	btrfs_set_root_refs(&root_item, 1);
+	itemoff = LEAF_DATA_SIZE - sizeof(root_item);
+	btrfs_set_item_offset(&item, itemoff);
+	btrfs_set_item_size(&item, sizeof(root_item));
+	btrfs_set_key_objectid(&item.key, BTRFS_EXTENT_TREE_OBJECTID);
+	btrfs_set_key_offset(&item.key, 0);
+	btrfs_set_key_flags(&item.key, 0);
+	memcpy(empty_leaf.items, &item, sizeof(item));
+	memcpy(empty_leaf.data + itemoff, &root_item, sizeof(root_item));
+
+	btrfs_set_root_blocknr(&root_item, 19);
+	itemoff = itemoff - sizeof(root_item);
+	btrfs_set_item_offset(&item, itemoff);
+	btrfs_set_key_objectid(&item.key, BTRFS_FS_TREE_OBJECTID);
+	memcpy(empty_leaf.items + 1, &item, sizeof(item));
+	memcpy(empty_leaf.data + itemoff, &root_item, sizeof(root_item));
+	ret = pwrite(fd, &empty_leaf, blocksize, 17 * blocksize);
+
+	/* create the items for the extent tree */
+	btrfs_set_header_parentid(&empty_leaf.header,
+				  BTRFS_EXTENT_TREE_OBJECTID);
+	btrfs_set_header_blocknr(&empty_leaf.header, 18);
+	btrfs_set_header_nritems(&empty_leaf.header, 4);
+
+	/* item1, reserve blocks 0-16 */
+	btrfs_set_key_objectid(&item.key, 0);
+	btrfs_set_key_offset(&item.key, 17);
+	btrfs_set_key_flags(&item.key, 0);
+	itemoff = LEAF_DATA_SIZE - sizeof(struct btrfs_extent_item);
+	btrfs_set_item_offset(&item, itemoff);
+	btrfs_set_item_size(&item, sizeof(struct btrfs_extent_item));
+	btrfs_set_extent_refs(&extent_item, 1);
+	btrfs_set_extent_owner(&extent_item, 0);
+	memcpy(empty_leaf.items, &item, sizeof(item));
+	memcpy(empty_leaf.data + btrfs_item_offset(&item), &extent_item,
+		btrfs_item_size(&item));
+
+	/* item2, give block 17 to the root */
+	btrfs_set_key_objectid(&item.key, 17);
+	btrfs_set_key_offset(&item.key, 1);
+	itemoff = itemoff - sizeof(struct btrfs_extent_item);
+	btrfs_set_item_offset(&item, itemoff);
+	btrfs_set_extent_owner(&extent_item, BTRFS_ROOT_TREE_OBJECTID);
+	memcpy(empty_leaf.items + 1, &item, sizeof(item));
+	memcpy(empty_leaf.data + btrfs_item_offset(&item), &extent_item,
+		btrfs_item_size(&item));
+
+	/* item3, give block 18 to the extent root */
+	btrfs_set_key_objectid(&item.key, 18);
+	btrfs_set_key_offset(&item.key, 1);
+	itemoff = itemoff - sizeof(struct btrfs_extent_item);
+	btrfs_set_item_offset(&item, itemoff);
+	btrfs_set_extent_owner(&extent_item, BTRFS_EXTENT_TREE_OBJECTID);
+	memcpy(empty_leaf.items + 2, &item, sizeof(item));
+	memcpy(empty_leaf.data + btrfs_item_offset(&item), &extent_item,
+		btrfs_item_size(&item));
+
+	/* item4, give block 19 to the FS root */
+	btrfs_set_key_objectid(&item.key, 19);
+	btrfs_set_key_offset(&item.key, 1);
+	itemoff = itemoff - sizeof(struct btrfs_extent_item);
+	btrfs_set_item_offset(&item, itemoff);
+	btrfs_set_extent_owner(&extent_item, BTRFS_FS_TREE_OBJECTID);
+	memcpy(empty_leaf.items + 3, &item, sizeof(item));
+	memcpy(empty_leaf.data + btrfs_item_offset(&item), &extent_item,
+		btrfs_item_size(&item));
+	ret = pwrite(fd, &empty_leaf, blocksize, 18 * blocksize);
+	if (ret != sizeof(empty_leaf))
+		return -1;
+
+	/* finally create the FS root */
+	btrfs_set_header_parentid(&empty_leaf.header, BTRFS_FS_TREE_OBJECTID);
+	btrfs_set_header_blocknr(&empty_leaf.header, 19);
+	btrfs_set_header_nritems(&empty_leaf.header, 0);
+	ret = pwrite(fd, &empty_leaf, blocksize, 19 * blocksize);
+	if (ret != sizeof(empty_leaf))
+		return -1;
+	return 0;
+}
+
+#if 0
 int mkfs(int fd)
 {
 	struct btrfs_root_info info[2];
@@ -20,13 +134,14 @@
 
 	/* setup the super block area */
 	memset(info, 0, sizeof(info));
-	info[0].blocknr = 16;
-	info[0].objectid = 1;
-	info[0].tree_root = 17;
+	btrfs_set_root_blocknr(info, 16);
+	btrfs_set_root_objectid(info, 1);
+	btrfs_set_root_tree_root(info, 17);
 
-	info[1].blocknr = 16;
-	info[1].objectid = 2;
-	info[1].tree_root = 18;
+	btrfs_set_root_blocknr(info + 1, 16);
+	btrfs_set_root_objectid(info + 1, 2);
+	btrfs_set_root_tree_root(info + 1, 18);
+
 	ret = pwrite(fd, info, sizeof(info),
 		     BTRFS_SUPER_INFO_OFFSET(BTRFS_BLOCKSIZE));
 	if (ret != sizeof(info))
@@ -81,3 +196,4 @@
 		return -1;
 	return 0;
 }
+#endif