diff --git a/Makefile b/Makefile
index 62a43b93..63514021 100644
--- a/Makefile
+++ b/Makefile
@@ -47,8 +47,11 @@ dir-test: $(objects) dir-test.o
 quick-test: $(objects) quick-test.o
 	gcc $(CFLAGS) -o quick-test $(objects) quick-test.o $(LDFLAGS)
 
+convert: $(objects) convert.o utils.o
+	gcc $(CFLAGS) -o btrfs-convert $(objects) convert.o utils.o -luuid -lext2fs $(LDFLAGS)
+
 clean :
-	rm -f $(progs) cscope.out *.o .*.d
+	rm -f $(progs) cscope.out *.o .*.d btrfs-convert
 
 install: $(progs)
 	$(INSTALL) -m755 -d $(DESTDIR)$(bindir)
diff --git a/convert.c b/convert.c
new file mode 100644
index 00000000..343866e1
--- /dev/null
+++ b/convert.c
@@ -0,0 +1,1279 @@
+/*
+ * 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.
+ */
+
+#define _XOPEN_SOURCE 500
+#ifndef __CHECKER__
+#include <sys/ioctl.h>
+#include <sys/mount.h>
+#endif
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <uuid/uuid.h>
+#include <linux/fs.h>
+#include "kerncompat.h"
+#include "ctree.h"
+#include "disk-io.h"
+#include "transaction.h"
+#include "utils.h"
+#include "ext2fs/ext2_fs.h"
+#include "ext2fs/ext2fs.h"
+
+#define INO_OFFSET (BTRFS_FIRST_FREE_OBJECTID - EXT2_ROOT_INO)
+
+/*
+ * Open Ext2fs in readonly mode, read block allocation bitmap and
+ * inode bitmap into memory.
+ */
+static int open_ext2fs(char *name, ext2_filsys *ret_fs)
+{
+	int mnt_flags;
+	errcode_t ret;
+	ext2_filsys ext2_fs;
+
+	ret = ext2fs_check_if_mounted(name, &mnt_flags);
+	if (ret) {
+		fprintf(stderr, "ext2fs_check_if_mounted: %s\n",
+			error_message(ret));
+		return -1;
+	}
+	if (mnt_flags & EXT2_MF_MOUNTED) {
+		fprintf(stderr, "%s is mounted\n", name);
+		return -1;
+	}
+	ret = ext2fs_open(name, 0, 0, 0, unix_io_manager, &ext2_fs);
+	if (ret) {
+		fprintf(stderr, "ext2fs_open: %s\n", error_message(ret));
+		goto fail;
+	}
+	ret = ext2fs_read_inode_bitmap(ext2_fs);
+	if (ret) {
+		fprintf(stderr, "ext2fs_read_inode_bitmap: %s\n",
+			error_message(ret));
+		goto fail;
+	}
+	ret = ext2fs_read_block_bitmap(ext2_fs);
+	if (ret) {
+		fprintf(stderr, "ext2fs_read_block_bitmap: %s\n",
+			error_message(ret));
+		goto fail;
+	}
+	*ret_fs = ext2_fs;
+	return 0;
+fail:
+	return -1;
+}
+
+static int close_ext2fs(ext2_filsys fs)
+{
+	ext2fs_close(fs);
+	return 0;
+}
+
+/*
+ * Stupid algorithm, search forward starting from the first free block.
+ */
+static int ext2_alloc_block(ext2_filsys fs, u64 goal, u64 *block_ret)
+{
+	blk_t block;
+
+	if (!ext2fs_new_block(fs, goal, NULL, &block)) {
+		ext2fs_fast_mark_block_bitmap(fs->block_map, block);
+		*block_ret = block;
+		return 0;
+	}
+	return -ENOSPC;
+}
+
+static int ext2_free_block(ext2_filsys fs, u64 block)
+{
+	BUG_ON(block != (blk_t)block);
+	ext2fs_fast_unmark_block_bitmap(fs->block_map, block);
+	return 0;
+}
+
+static int custom_alloc_extent(struct btrfs_root *root, u64 num_bytes,
+			       u64 hint_byte, struct btrfs_key *ins)
+{
+	ext2_filsys fs = (ext2_filsys)root->fs_info->priv_data;
+	u32 blocksize = fs->blocksize;
+	u64 block;
+	u64 bytenr;
+	int ret;
+
+	block = hint_byte / blocksize;
+	BUG_ON(block != (blk_t)block);
+	BUG_ON(num_bytes != blocksize);
+	while (1) {
+		ret = ext2_alloc_block(fs, block, &block);
+		if (ret)
+			return ret;
+
+		bytenr = block * blocksize;
+		if (!test_range_bit(&root->fs_info->pinned_extents, bytenr,
+				    bytenr + blocksize - 1, EXTENT_DIRTY, 0))
+			break;
+
+		ext2_free_block(fs, block);
+		block++;
+	}
+	ins->objectid = bytenr;
+	ins->offset = blocksize;
+	btrfs_set_key_type(ins, BTRFS_EXTENT_ITEM_KEY);
+	return 0;
+}
+
+static int custom_free_extent(struct btrfs_root *root, u64 bytenr,
+			      u64 num_bytes)
+{
+	u64 block;
+	ext2_filsys fs = (ext2_filsys)root->fs_info->priv_data;
+
+	BUG_ON(bytenr & (fs->blocksize - 1));
+	block = bytenr / fs->blocksize;
+	while (num_bytes > 0) {
+		ext2_free_block(fs, block);
+		block++;
+		num_bytes -= fs->blocksize;
+	}
+	return 0;
+}
+
+struct btrfs_extent_ops extent_ops = {
+	.alloc_extent = custom_alloc_extent,
+	.free_extent = custom_free_extent,
+};
+
+struct dir_iterate_data {
+	struct btrfs_trans_handle *trans;
+	struct btrfs_root *root;
+	struct btrfs_inode_item *inode;
+	u64 objectid;
+	u32 parent;
+	int errcode;
+};
+
+static u8 filetype_conversion_table[EXT2_FT_MAX] = {
+	[EXT2_FT_UNKNOWN]	= BTRFS_FT_UNKNOWN,
+	[EXT2_FT_REG_FILE]	= BTRFS_FT_REG_FILE,
+	[EXT2_FT_DIR]		= BTRFS_FT_DIR,
+	[EXT2_FT_CHRDEV]	= BTRFS_FT_CHRDEV,
+	[EXT2_FT_BLKDEV]	= BTRFS_FT_BLKDEV,
+	[EXT2_FT_FIFO]		= BTRFS_FT_FIFO,
+	[EXT2_FT_SOCK]		= BTRFS_FT_SOCK,
+	[EXT2_FT_SYMLINK]	= BTRFS_FT_SYMLINK,
+};
+
+static int dir_iterate_proc(ext2_ino_t dir, int entry,
+			    struct ext2_dir_entry *old,
+			    int offset, int blocksize,
+			    char *buf,void *priv_data)
+{
+	int ret;
+	int file_type;
+	u64 objectid;
+        u64 inode_size;
+	char dotdot[] = "..";
+	struct btrfs_key location;
+	struct ext2_dir_entry_2 *dirent = (struct ext2_dir_entry_2 *)old;
+	struct dir_iterate_data *idata = (struct dir_iterate_data *)priv_data;
+
+	objectid = dirent->inode + INO_OFFSET;
+	if (!strncmp(dirent->name, dotdot, dirent->name_len)) {
+		if (dirent->name_len == 2) {
+			BUG_ON(idata->parent != 0);
+			idata->parent = objectid;
+		}
+		return 0;
+	}
+	if (dirent->inode < EXT2_GOOD_OLD_FIRST_INO)
+		return 0;
+
+	location.objectid = objectid;
+	location.offset = 0;
+	btrfs_set_key_type(&location, BTRFS_INODE_ITEM_KEY);
+
+	file_type = dirent->file_type;
+	BUG_ON(file_type > EXT2_FT_SYMLINK);
+	ret = btrfs_insert_dir_item(idata->trans, idata->root,
+				    dirent->name, dirent->name_len,
+				    idata->objectid, &location,
+				    filetype_conversion_table[file_type]);
+	if (ret)
+		goto fail;
+	ret = btrfs_insert_inode_ref(idata->trans, idata->root,
+				     dirent->name, dirent->name_len,
+				     objectid, idata->objectid);
+	if (ret)
+		goto fail;
+	inode_size = btrfs_stack_inode_size(idata->inode) +
+		     dirent->name_len * 2;
+	btrfs_set_stack_inode_size(idata->inode, inode_size);
+	return 0;
+fail:
+	idata->errcode = ret;
+	return BLOCK_ABORT;
+}
+
+static int create_dir_entries(struct btrfs_trans_handle *trans,
+			      struct btrfs_root *root, u64 objectid,
+			      struct btrfs_inode_item *btrfs_inode,
+			      ext2_filsys ext2_fs, ext2_ino_t ext2_ino)
+{
+	int ret;
+	errcode_t err;
+	struct dir_iterate_data data = {
+		.trans		= trans,
+		.root		= root,
+		.inode		= btrfs_inode,
+		.objectid	= objectid,
+		.parent		= 0,
+		.errcode	= 0,
+	};
+
+	err = ext2fs_dir_iterate2(ext2_fs, ext2_ino, 0, NULL,
+				  dir_iterate_proc, &data);
+	if (err)
+		goto error;
+	ret = data.errcode;
+	if (ret == 0 && data.parent == objectid) {
+		ret = btrfs_insert_inode_ref(trans, root, "..", 2,
+					     objectid, objectid);
+	}
+	return ret;
+error:
+	fprintf(stderr, "ext2fs_dir_iterate2: %s\n", error_message(err));
+	return -1;
+}
+
+static int read_disk_extent(struct btrfs_root *root, u64 bytenr,
+		            u32 num_bytes, char *buffer)
+{
+	int ret;
+	struct btrfs_fs_info *fs_info = root->fs_info;
+
+	ret = pread(fs_info->fp, buffer, num_bytes, bytenr);
+	if (ret != num_bytes)
+		goto fail;
+	ret = 0;
+fail:
+	if (ret > 0)
+		ret = -1;
+	return ret;
+}
+
+/*
+ * record a single file extent. do all required works:
+ * 1. insert a btrfs_file_extent_item into fs tree.
+ * 2. compute checksum and insert btrfs_csum_item into fs tree.
+ * 3. insert extent item and extent backref into extent tree.
+ */
+static int record_file_extent(struct btrfs_trans_handle *trans,
+			      struct btrfs_root *root, u64 objectid,
+			      struct btrfs_inode_item *inode,
+			      u64 file_pos, u64 disk_bytenr,
+			      u64 num_bytes, int checksum)
+{
+	int ret;
+	struct btrfs_fs_info *info = root->fs_info;
+	struct btrfs_root *extent_root = info->extent_root;
+	struct btrfs_key ins_key;
+	struct btrfs_path path;
+	struct btrfs_extent_item extent_item;
+	u32 blocksize = root->sectorsize;
+	u64 nblocks;
+	u64 bytes_used;
+
+	ret = btrfs_insert_file_extent(trans, root, objectid, file_pos,
+				       disk_bytenr, num_bytes, num_bytes);
+	if (ret || disk_bytenr == 0)
+		return ret;
+
+	nblocks = btrfs_stack_inode_nblocks(inode) + num_bytes / 512;
+	btrfs_set_stack_inode_nblocks(inode, nblocks);
+	if (checksum) {
+		u64 offset;
+		char *buffer;
+
+		ret = -ENOMEM;
+		buffer = malloc(blocksize);
+		if (!buffer)
+			goto fail;
+		for (offset = 0; offset < num_bytes; offset += blocksize) {
+			ret = read_disk_extent(root, disk_bytenr + offset,
+						blocksize, buffer);
+			if (ret)
+				break;
+			ret = btrfs_csum_file_block(trans, root, inode,
+						objectid, file_pos + offset,
+						buffer, blocksize);
+			if (ret)
+				break;
+		}
+		free(buffer);
+		if (ret)
+			goto fail;
+	}
+
+	bytes_used = btrfs_root_used(&root->root_item);
+	btrfs_set_root_used(&root->root_item, bytes_used + num_bytes);
+	ins_key.objectid = disk_bytenr;
+	ins_key.offset = num_bytes;
+	btrfs_set_key_type(&ins_key, BTRFS_EXTENT_ITEM_KEY);
+	btrfs_set_stack_extent_refs(&extent_item, 1);
+	ret = btrfs_insert_item(trans, extent_root, &ins_key,
+				&extent_item, sizeof(extent_item));
+	if (ret == 0) {
+		bytes_used = btrfs_super_bytes_used(&info->super_copy);
+		btrfs_set_super_bytes_used(&info->super_copy, bytes_used +
+					   num_bytes);
+		btrfs_init_path(&path);
+		ret = btrfs_insert_extent_backref(trans, extent_root, &path,
+					disk_bytenr, root->root_key.objectid,
+					trans->transid, objectid, file_pos);
+		if (ret)
+			goto fail;
+		ret = btrfs_update_block_group(trans, root, disk_bytenr,
+					       num_bytes, 1, 0, 1);
+	} else if (ret == -EEXIST) {
+		ret = btrfs_inc_extent_ref(trans, root, disk_bytenr, num_bytes,
+					   root->root_key.objectid,
+					   trans->transid, objectid, file_pos);
+	}
+	if (ret)
+		goto fail;
+	btrfs_extent_post_op(trans, extent_root);
+	return 0;
+fail:
+	return ret;
+}
+
+static int record_file_blocks(struct btrfs_trans_handle *trans,
+			      struct btrfs_root *root, u64 objectid,
+			      struct btrfs_inode_item *inode,
+			      u64 file_block, u64 disk_block,
+			      u64 num_blocks, int checksum)
+{
+	u64 file_pos = file_block * root->sectorsize;
+	u64 disk_bytenr = disk_block * root->sectorsize;
+	u64 num_bytes = num_blocks * root->sectorsize;
+	return record_file_extent(trans, root, objectid, inode, file_pos,
+				  disk_bytenr, num_bytes, checksum);
+}
+
+struct blk_iterate_data {
+	struct btrfs_trans_handle *trans;
+	struct btrfs_root *root;
+	struct btrfs_inode_item *inode;
+	u64 objectid;
+	u64 first_block;
+	u64 disk_block;
+	u64 num_blocks;
+	int checksum;
+	int errcode;
+};
+
+static int block_iterate_proc(ext2_filsys ext2_fs,
+			      u64 disk_block, u64 file_block,
+		              struct blk_iterate_data *idata)
+{
+	int ret;
+	u32 blocksize = ext2_fs->blocksize;
+	struct btrfs_root *root = idata->root;
+	struct btrfs_trans_handle *trans = idata->trans;
+
+	if ((file_block > idata->first_block + idata->num_blocks) ||
+	    (disk_block != idata->disk_block + idata->num_blocks) ||
+	    (idata->num_blocks >= BTRFS_BLOCK_GROUP_SIZE / blocksize)) {
+		if (idata->num_blocks > 0) {
+			ret = record_file_blocks(trans, root, idata->objectid,
+					idata->inode, idata->first_block,
+					idata->disk_block, idata->num_blocks,
+					idata->checksum);
+			if (ret)
+				goto fail;
+			idata->first_block += idata->num_blocks;
+			idata->num_blocks = 0;
+		}
+		if (file_block > idata->first_block) {
+			ret = record_file_blocks(trans, root, idata->objectid,
+					idata->inode, idata->first_block,
+					0, file_block - idata->first_block,
+					idata->checksum);
+			if (ret)
+				goto fail;
+		}
+		idata->first_block = file_block;
+		idata->disk_block = disk_block;
+	}
+	idata->num_blocks++;
+	return 0;
+fail:
+	idata->errcode = ret;
+	return BLOCK_ABORT;
+}
+
+static int __block_iterate_proc(ext2_filsys fs, blk_t *blocknr,
+			        e2_blkcnt_t blockcnt, blk_t ref_block,
+			        int ref_offset, void *priv_data)
+{
+	struct blk_iterate_data *idata;
+	idata = (struct blk_iterate_data *)priv_data;
+	return block_iterate_proc(fs, *blocknr, blockcnt, idata);
+}
+
+/*
+ * traverse file's data blocks, record these data blocks as file extents.
+ */
+static int create_file_extents(struct btrfs_trans_handle *trans,
+			       struct btrfs_root *root, u64 objectid,
+			       struct btrfs_inode_item *btrfs_inode,
+			       ext2_filsys ext2_fs, ext2_ino_t ext2_ino,
+			       struct ext2_inode *ext2_inode)
+{
+	int ret;
+	char *buffer = NULL;
+	errcode_t err;
+	u32 last_block;
+	u32 sectorsize = root->sectorsize;
+	u64 inode_size = btrfs_stack_inode_size(btrfs_inode);
+	struct blk_iterate_data data = {
+		.trans		= trans,
+		.root		= root,
+		.inode		= btrfs_inode,
+		.objectid	= objectid,
+		.first_block	= 0,
+		.disk_block	= 0,
+		.num_blocks	= 0,
+		.checksum	= 1,
+		.errcode	= 0,
+	};
+
+	err = ext2fs_block_iterate2(ext2_fs, ext2_ino, BLOCK_FLAG_DATA_ONLY,
+				    NULL, __block_iterate_proc, &data);
+	if (err)
+		goto error;
+	ret = data.errcode;
+	if (ret)
+		goto fail;
+
+	if (data.first_block == 0 && data.num_blocks > 0 &&
+	    inode_size <= BTRFS_MAX_INLINE_DATA_SIZE(root)) {
+		u64 num_bytes = data.num_blocks * sectorsize;
+		u64 disk_bytenr = data.disk_block * sectorsize;
+
+		buffer = malloc(num_bytes);
+		if (!buffer)
+			return -ENOMEM;
+		ret = read_disk_extent(root, disk_bytenr, num_bytes, buffer);
+		if (ret)
+			goto fail;
+		if (num_bytes > inode_size)
+			num_bytes = inode_size;
+		ret = btrfs_insert_inline_extent(trans, root, objectid,
+						 0, buffer, num_bytes);
+		if (ret)
+			goto fail;
+	} else if (data.num_blocks > 0) {
+		ret = record_file_blocks(trans, root, objectid, btrfs_inode,
+					 data.first_block, data.disk_block,
+					 data.num_blocks, 1);
+		if (ret)
+			goto fail;
+	}
+	data.first_block += data.num_blocks;
+	last_block = (inode_size + sectorsize - 1) / sectorsize;
+	if (last_block > data.first_block) {
+		ret = record_file_blocks(trans, root, objectid, btrfs_inode,
+					 data.first_block, 0, last_block -
+					 data.first_block, 1);
+	}
+fail:
+	if (buffer)
+		free(buffer);
+	return ret;
+error:
+	fprintf(stderr, "ext2fs_block_iterate2: %s\n", error_message(err));
+	return -1;
+}
+
+static int create_symbol_link(struct btrfs_trans_handle *trans,
+			      struct btrfs_root *root, u64 objectid,
+			      struct btrfs_inode_item *btrfs_inode,
+			      ext2_filsys ext2_fs, ext2_ino_t ext2_ino,
+			      struct ext2_inode *ext2_inode)
+{
+	int ret;
+	char *pathname;
+	u64 inode_size = btrfs_stack_inode_size(btrfs_inode);
+
+	if (ext2fs_inode_data_blocks(ext2_fs, ext2_inode)) {
+		btrfs_set_stack_inode_size(btrfs_inode, inode_size + 1);
+		ret = create_file_extents(trans, root, objectid, btrfs_inode,
+					  ext2_fs, ext2_ino, ext2_inode);
+		btrfs_set_stack_inode_size(btrfs_inode, inode_size);
+		return ret;
+	}
+
+	pathname = (char *)&(ext2_inode->i_block[0]);
+	BUG_ON(pathname[inode_size] != 0);
+	ret = btrfs_insert_inline_extent(trans, root, objectid, 0,
+					 pathname, inode_size + 1);
+	return ret;
+}
+
+#define MINORBITS	20
+#define MKDEV(ma, mi)	(((ma) << MINORBITS) | (mi))
+
+static inline dev_t old_decode_dev(u16 val)
+{
+	return MKDEV((val >> 8) & 255, val & 255);
+}
+
+static inline dev_t new_decode_dev(u32 dev)
+{
+	unsigned major = (dev & 0xfff00) >> 8;
+	unsigned minor = (dev & 0xff) | ((dev >> 12) & 0xfff00);
+	return MKDEV(major, minor);
+}
+
+static int copy_inode_item(struct btrfs_inode_item *dst,
+			   struct ext2_inode *src)
+{
+	btrfs_set_stack_inode_generation(dst, 0);
+	btrfs_set_stack_inode_size(dst, src->i_size);
+	btrfs_set_stack_inode_nblocks(dst, src->i_blocks);
+	btrfs_set_stack_inode_block_group(dst, 0);
+	btrfs_set_stack_inode_nblocks(dst, 0);
+	btrfs_set_stack_inode_nlink(dst, src->i_links_count);
+	btrfs_set_stack_inode_uid(dst, src->i_uid | (src->i_uid_high << 16));
+	btrfs_set_stack_inode_gid(dst, src->i_gid | (src->i_gid_high << 16));
+	btrfs_set_stack_inode_mode(dst, src->i_mode);
+	btrfs_set_stack_inode_rdev(dst, 0);
+	btrfs_set_stack_inode_flags(dst, 0);
+	btrfs_set_stack_inode_compat_flags(dst, 0);
+	btrfs_set_stack_timespec_sec(&dst->atime, src->i_atime);
+	btrfs_set_stack_timespec_nsec(&dst->atime, 0);
+	btrfs_set_stack_timespec_sec(&dst->ctime, src->i_ctime);
+	btrfs_set_stack_timespec_nsec(&dst->ctime, 0);
+	btrfs_set_stack_timespec_sec(&dst->mtime, src->i_mtime);
+	btrfs_set_stack_timespec_nsec(&dst->mtime, 0);
+	btrfs_set_stack_timespec_sec(&dst->otime, 0);
+	btrfs_set_stack_timespec_nsec(&dst->otime, 0);
+
+	if (S_ISDIR(src->i_mode)) {
+		btrfs_set_stack_inode_size(dst, 0);
+		btrfs_set_stack_inode_nlink(dst, 1);
+	}
+	if (!S_ISREG(src->i_mode) && !S_ISDIR(src->i_mode) &&
+	    !S_ISLNK(src->i_mode)) {
+		if (src->i_block[0]) {
+			btrfs_set_stack_inode_rdev(dst,
+				old_decode_dev(src->i_block[0]));
+		} else {
+			btrfs_set_stack_inode_rdev(dst,
+				new_decode_dev(src->i_block[1]));
+		}
+	}
+	return 0;
+}
+
+/*
+ * copy a single inode. do all the required works, such as cloning
+ * inode item, creating file extents and creating directory entries.
+ */
+static int copy_single_inode(struct btrfs_trans_handle *trans,
+			     struct btrfs_root *root, u64 objectid,
+			     ext2_filsys ext2_fs, ext2_ino_t ext2_ino)
+{
+	int ret;
+	errcode_t err;
+	struct ext2_inode ext2_inode;
+	struct btrfs_key inode_key;
+	struct btrfs_inode_item btrfs_inode;
+
+	err = ext2fs_read_inode(ext2_fs, ext2_ino, &ext2_inode);
+	if (err)
+		goto error;
+
+	if (!ext2_inode.i_links_count &&
+	    (!ext2_inode.i_mode || ext2_inode.i_dtime)) {
+		printf("skip inode %u\n", ext2_ino);
+		return 0;
+	}
+
+	copy_inode_item(&btrfs_inode, &ext2_inode);
+
+	ret = 0;
+	switch (ext2_inode.i_mode & S_IFMT) {
+	case S_IFREG:
+		ret = create_file_extents(trans, root, objectid, &btrfs_inode,
+					  ext2_fs, ext2_ino, &ext2_inode);
+		break;
+	case S_IFLNK:
+		ret = create_symbol_link(trans, root, objectid, &btrfs_inode,
+					 ext2_fs, ext2_ino, &ext2_inode);
+		break;
+	case S_IFDIR:
+		ret = create_dir_entries(trans, root, objectid,
+					 &btrfs_inode, ext2_fs, ext2_ino);
+		break;
+	default:
+		ret = 0;
+		break;
+	}
+	if (ret)
+		return ret;
+	inode_key.objectid = objectid;
+	inode_key.offset = 0;
+	btrfs_set_key_type(&inode_key, BTRFS_INODE_ITEM_KEY);
+	ret = btrfs_insert_inode(trans, root, objectid, &btrfs_inode);
+	return ret;
+error:
+	fprintf(stderr, "ext2fs_read_inode: %s\n", error_message(err));
+	return -1;
+}
+
+static int copy_disk_extent(struct btrfs_root *root, u64 dst_bytenr,
+		            u64 src_bytenr, u32 num_bytes)
+{
+	int ret;
+	char *buffer;
+	struct btrfs_fs_info *fs_info = root->fs_info;
+
+	buffer = malloc(num_bytes);
+	if (!buffer)
+		return -ENOMEM;
+	ret = pread(fs_info->fp, buffer, num_bytes, src_bytenr);
+	if (ret != num_bytes)
+		goto fail;
+	ret = pwrite(fs_info->fp, buffer, num_bytes, dst_bytenr);
+	if (ret != num_bytes)
+		goto fail;
+	ret = 0;
+fail:
+	free(buffer);
+	if (ret > 0)
+		ret = -1;
+	return ret;
+}
+
+/*
+ * scan ext2's inode bitmap and copy all used inode.
+ */
+static int copy_inodes(struct btrfs_root *root, ext2_filsys ext2_fs)
+{
+	int ret;
+	ext2_ino_t ext2_ino;
+	u64 objectid;
+	struct btrfs_trans_handle *trans;
+
+	trans = btrfs_start_transaction(root, 1);
+	if (!trans)
+		return -ENOMEM;
+	ext2_ino = ext2_fs->inode_map->start;
+	for (; ext2_ino <= ext2_fs->inode_map->end; ext2_ino++) {
+		if (ext2fs_fast_test_inode_bitmap(ext2_fs->inode_map,
+						  ext2_ino)) {
+			/* skip special inode in ext2fs */
+			if (ext2_ino < EXT2_GOOD_OLD_FIRST_INO &&
+			    ext2_ino != EXT2_ROOT_INO)
+				continue;
+			objectid = ext2_ino + INO_OFFSET;
+			ret = copy_single_inode(trans, root, objectid,
+						ext2_fs, ext2_ino);
+			if (ret)
+				return ret;
+		}
+		if (trans->blocks_used >= 8192) {
+			ret = btrfs_commit_transaction(trans, root);
+			BUG_ON(ret);
+			trans = btrfs_start_transaction(root, 1);
+			BUG_ON(!trans);
+		}
+	}
+	ret = btrfs_commit_transaction(trans, root);
+	BUG_ON(ret);
+
+	return ret;
+}
+
+static int lookup_extent_ref(struct btrfs_trans_handle *trans,
+			     struct btrfs_root *root,
+			     u64 bytenr, u64 num_bytes)
+{
+	int ret;
+	struct btrfs_key key;
+	struct btrfs_path path;
+
+	btrfs_init_path(&path);
+	key.objectid = bytenr;
+	key.type = BTRFS_EXTENT_ITEM_KEY;
+	key.offset = num_bytes;
+	ret = btrfs_search_slot(trans, root->fs_info->extent_root,
+				&key, &path, 0, 0);
+	btrfs_release_path(root, &path);
+	return ret;
+}
+
+/*
+ * Construct a range of ext2fs image file.
+ * scan block allocation bitmap, find all blocks used by the ext2fs
+ * in this range and create file extents that point to these blocks.
+ */
+static int create_image_file_range(struct btrfs_trans_handle *trans,
+				   struct btrfs_root *root, u64 objectid,
+				   struct btrfs_inode_item *inode,
+				   u64 start_byte, u64 end_byte,
+				   ext2_filsys ext2_fs)
+{
+	u64 bytenr;
+	u32 blocksize = ext2_fs->blocksize;
+	u32 block = start_byte / blocksize;
+	u32 last_block = (end_byte + blocksize - 1) / blocksize;
+	int ret;
+	struct blk_iterate_data data = {
+		.trans		= trans,
+		.root		= root,
+		.inode		= inode,
+		.objectid	= objectid,
+		.first_block	= block,
+		.disk_block	= block,
+		.num_blocks	= 0,
+		.checksum	= 1,
+		.errcode	= 0,
+	};
+
+	for (; start_byte < end_byte; block++, start_byte += blocksize) {
+		if (!ext2fs_fast_test_block_bitmap(ext2_fs->block_map, block))
+			continue;
+		/* the bit may be set by us, check extent tree */
+		bytenr = (u64)block * blocksize;
+		ret = lookup_extent_ref(trans, root, bytenr, blocksize);
+		if (ret < 0)
+			goto fail;
+		if (ret == 0)
+			continue;
+
+		ret = block_iterate_proc(ext2_fs, block, block, &data);
+		if (ret & BLOCK_ABORT)
+			break;
+	}
+	ret = data.errcode;
+	if (ret)
+		return ret;
+	if (data.num_blocks > 0) {
+		ret = record_file_blocks(trans, root, objectid, inode,
+					 data.first_block, data.disk_block,
+					 data.num_blocks, 1);
+		if (ret)
+			return ret;
+		data.first_block += data.num_blocks;
+	}
+	if (last_block > data.first_block) {
+		ret = record_file_blocks(trans, root, objectid, inode,
+					 data.first_block, 0, last_block -
+					 data.first_block, 1);
+		if (ret)
+			return ret;
+	}
+fail:
+	return 0;
+}
+
+/*
+ * Create the ext2fs image file.
+ */
+static int create_ext2_image(struct btrfs_root *root, char *name,
+			     int namelen, ext2_filsys ext2_fs)
+{
+	int ret;
+	struct btrfs_key key;
+	struct btrfs_key location;
+	struct btrfs_path path;
+	struct btrfs_inode_item btrfs_inode;
+	struct extent_buffer *leaf;
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	struct btrfs_root *extent_root = fs_info->extent_root;
+	struct btrfs_trans_handle *trans;
+	struct btrfs_extent_ref *ref_item;
+	u64 bytenr;
+	u64 num_bytes;
+	u64 ref_root;
+	u64 ref_owner;
+	u64 objectid;
+	u64 new_block;
+	u64 last_byte;
+	u64 first_free;
+	u64 total_bytes;
+	u32 sectorsize = root->sectorsize;
+	int slot;
+	int file_extent;
+
+	total_bytes = btrfs_super_total_bytes(&fs_info->super_copy);
+	first_free =  BTRFS_SUPER_INFO_OFFSET + sectorsize * 2 - 1;
+	first_free &= ~((u64)sectorsize - 1);
+
+	memset(&btrfs_inode, 0, sizeof(btrfs_inode));
+	btrfs_set_stack_inode_generation(&btrfs_inode, 1);
+	btrfs_set_stack_inode_size(&btrfs_inode, total_bytes);
+	btrfs_set_stack_inode_nlink(&btrfs_inode, 1);
+	btrfs_set_stack_inode_nblocks(&btrfs_inode, 0);
+	btrfs_set_stack_inode_mode(&btrfs_inode, S_IFREG | 0444);
+
+	btrfs_init_path(&path);
+	trans = btrfs_start_transaction(root, 1);
+	BUG_ON(!trans);
+
+	objectid = btrfs_root_dirid(&root->root_item);
+	ret = btrfs_find_free_objectid(trans, root, objectid, &objectid);
+	if (ret)
+		goto fail;
+
+	/*
+	 * copy the first a few blocks to new positions. the relocation is
+	 * reuqired for block 0 and default btrfs super block.
+	 */
+	for (last_byte = 0; last_byte < first_free; last_byte += sectorsize) {
+		ret = ext2_alloc_block(ext2_fs, 0, &new_block);
+		if (ret)
+			goto fail;
+		new_block *= sectorsize;
+		ret = copy_disk_extent(root, new_block, last_byte, sectorsize);
+		if (ret)
+			goto fail;
+		ret = record_file_extent(trans, root, objectid,
+					 &btrfs_inode, last_byte,
+					 new_block, sectorsize, 1);
+		if (ret)
+			goto fail;
+	}
+again:
+	if (trans->blocks_used >= 8192) {
+		ret = btrfs_commit_transaction(trans, root);
+		BUG_ON(ret);
+		trans = btrfs_start_transaction(root, 1);
+		BUG_ON(!trans);
+	}
+
+	key.objectid = last_byte;
+	key.offset = 0;
+	btrfs_set_key_type(&key, BTRFS_EXTENT_ITEM_KEY);
+	btrfs_release_path(extent_root, &path);
+	ret = btrfs_search_slot(trans, fs_info->extent_root,
+				&key, &path, 0, 0);
+	if (ret < 0)
+		goto fail;
+
+	leaf = path.nodes[0];
+	slot = path.slots[0];
+	while(1) {
+		if (slot >= btrfs_header_nritems(leaf)) {
+			ret = btrfs_next_leaf(extent_root, &path);
+			if (ret < 0)
+				goto fail;
+			if (ret > 0)
+				break;
+			leaf = path.nodes[0];
+			slot = path.slots[0];
+		}
+		btrfs_item_key_to_cpu(leaf, &key, slot);
+		if (last_byte > key.objectid ||
+		    key.type != BTRFS_EXTENT_ITEM_KEY) {
+			slot++;
+			continue;
+		}
+
+		bytenr = key.objectid;
+		num_bytes = key.offset;
+		file_extent = 0;
+		while (1) {
+			if (slot >= btrfs_header_nritems(leaf)) {
+				ret = btrfs_next_leaf(extent_root, &path);
+				if (ret > 0)
+					break;
+				if (ret < 0)
+					goto fail;
+				leaf = path.nodes[0];
+				slot = path.slots[0];
+			}
+			btrfs_item_key_to_cpu(leaf, &key, slot);
+			if (key.objectid != bytenr)
+				break;
+			if (key.type != BTRFS_EXTENT_REF_KEY) {
+				slot++;
+				continue;
+			}
+			ref_item = btrfs_item_ptr(leaf, slot,
+						  struct btrfs_extent_ref);
+			ref_root = btrfs_ref_root(leaf, ref_item);
+			ref_owner = btrfs_ref_objectid(leaf, ref_item);
+			if ((ref_root == BTRFS_FS_TREE_OBJECTID) &&
+			    (ref_owner >= BTRFS_FIRST_FREE_OBJECTID)) {
+				file_extent = 1;
+				break;
+			}
+			slot++;
+		}
+		if (!file_extent)
+			continue;
+
+		if (bytenr > last_byte) {
+			ret = create_image_file_range(trans, root, objectid,
+						      &btrfs_inode, last_byte,
+						      bytenr, ext2_fs);
+			if (ret)
+				goto fail;
+		}
+		ret = record_file_extent(trans, root, objectid, &btrfs_inode,
+					 bytenr, bytenr, num_bytes, 1);
+		if (ret)
+			goto fail;
+		last_byte = bytenr + num_bytes;
+		goto again;
+	}
+	if (total_bytes > last_byte) {
+		ret = create_image_file_range(trans, root, objectid,
+					      &btrfs_inode, last_byte,
+					      total_bytes, ext2_fs);
+		if (ret)
+			goto fail;
+	}
+
+	ret = btrfs_insert_inode(trans, root, objectid, &btrfs_inode);
+	if (ret)
+		goto fail;
+
+	location.objectid = objectid;
+	location.offset = 0;
+	btrfs_set_key_type(&location, BTRFS_INODE_ITEM_KEY);
+	ret = btrfs_insert_dir_item(trans, root, name, namelen,
+				    btrfs_root_dirid(&root->root_item),
+				    &location, EXT2_FT_REG_FILE);
+	if (ret)
+		goto fail;
+	ret = btrfs_insert_inode_ref(trans, root, name, namelen, objectid,
+				     btrfs_root_dirid(&root->root_item));
+	if (ret)
+		goto fail;
+	ret = btrfs_commit_transaction(trans, root);
+	BUG_ON(ret);
+fail:
+	btrfs_release_path(root, &path);
+	return ret;
+}
+
+struct btrfs_root *create_subvol(struct btrfs_root *root,
+				 char *name, int namelen)
+{
+	int ret;
+	u64 objectid;
+	struct btrfs_key location;
+	struct btrfs_root_item root_item;
+	struct btrfs_trans_handle *trans;
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	struct btrfs_root *tree_root = fs_info->tree_root;
+	struct btrfs_root *new_root;
+	struct extent_buffer *tmp;
+
+	trans = btrfs_start_transaction(root, 1);
+	BUG_ON(!trans);
+
+	objectid = btrfs_super_root_dir(&fs_info->super_copy);
+	ret = btrfs_find_free_objectid(trans, root, objectid, &objectid);
+	if (ret)
+		goto fail;
+	ret = btrfs_copy_root(trans, root, root->node, &tmp, objectid);
+	if (ret)
+		goto fail;
+	memcpy(&root_item, &root->root_item, sizeof(root_item));
+	btrfs_set_root_bytenr(&root_item, tmp->start);
+	btrfs_set_root_level(&root_item, btrfs_header_level(tmp));
+	free_extent_buffer(tmp);
+
+	location.objectid = objectid;
+	location.offset = 1;
+	btrfs_set_key_type(&location, BTRFS_ROOT_ITEM_KEY);
+	ret = btrfs_insert_root(trans, root->fs_info->tree_root,
+				&location, &root_item);
+	if (ret)
+		goto fail;
+	location.offset = (u64)-1;
+	ret = btrfs_insert_dir_item(trans, tree_root, name, namelen,
+				    btrfs_super_root_dir(&fs_info->super_copy),
+				    &location, BTRFS_FT_DIR);
+	if (ret)
+		goto fail;
+	ret = btrfs_insert_inode_ref(trans, tree_root, name, namelen, objectid,
+				     btrfs_super_root_dir(&fs_info->super_copy));
+	if (ret)
+		goto fail;
+	ret = btrfs_commit_transaction(trans, root);
+	BUG_ON(ret);
+
+	new_root = btrfs_read_fs_root(fs_info, &location);
+	if (!new_root) {
+		return NULL;
+	}
+
+	trans = btrfs_start_transaction(new_root, 1);
+	BUG_ON(!trans);
+	ret = btrfs_make_root_dir(trans, new_root, BTRFS_FIRST_FREE_OBJECTID);
+	if (ret)
+		goto fail;
+	ret = btrfs_commit_transaction(trans, new_root);
+	BUG_ON(ret);
+	return new_root;
+fail:
+	return NULL;
+}
+
+/*
+ * Fixup block accounting. The initial block accounting created by
+ * make_block_groups isn't accuracy in this case.
+ */
+static int fixup_block_accounting(struct btrfs_trans_handle *trans,
+				  struct btrfs_root *root)
+{
+	int ret;
+	int slot;
+	u64 start = 0;
+	u64 bytes_used = 0;
+	struct btrfs_path path;
+	struct btrfs_key key;
+	struct extent_buffer *leaf;
+	struct btrfs_block_group_cache *cache;
+	struct btrfs_fs_info *fs_info = root->fs_info;
+
+	while(1) {
+		cache = btrfs_lookup_block_group(fs_info, start);
+		if (!cache)
+			break;
+		start = cache->key.objectid + cache->key.offset;
+		btrfs_set_block_group_used(&cache->item, 0);
+	}
+
+	btrfs_init_path(&path);
+	key.offset = 0;
+	key.objectid = 0;
+	btrfs_set_key_type(&key, BTRFS_EXTENT_ITEM_KEY);
+	ret = btrfs_search_slot(trans, root->fs_info->extent_root,
+				&key, &path, 0, 0);
+	if (ret < 0)
+		return ret;
+	while(1) {
+		leaf = path.nodes[0];
+		slot = path.slots[0];
+		if (slot >= btrfs_header_nritems(leaf)) {
+			ret = btrfs_next_leaf(root, &path);
+			if (ret < 0)
+				return ret;
+			if (ret > 0)
+				break;
+			leaf = path.nodes[0];
+			slot = path.slots[0];
+		}
+		btrfs_item_key_to_cpu(leaf, &key, slot);
+		if (key.type == BTRFS_EXTENT_ITEM_KEY) {
+			bytes_used += key.offset;
+			ret = btrfs_update_block_group(trans, root,
+				  key.objectid, key.offset, 1, 0, 1);
+			BUG_ON(ret);
+		}
+		path.slots[0]++;
+	}
+	btrfs_set_super_bytes_used(&root->fs_info->super_copy, bytes_used);
+	btrfs_release_path(root, &path);
+	return 0;
+}
+
+static int init_btrfs(struct btrfs_root *root)
+{
+	int ret;
+	struct btrfs_key location;
+	struct btrfs_trans_handle *trans;
+	struct btrfs_fs_info *fs_info = root->fs_info;
+
+	trans = btrfs_start_transaction(root, 1);
+	BUG_ON(!trans);
+	ret = btrfs_make_block_groups(trans, root);
+	if (ret)
+		goto err;
+	ret = fixup_block_accounting(trans, root);
+	if (ret)
+		goto err;
+	ret = btrfs_make_root_dir(trans, fs_info->tree_root,
+				  BTRFS_ROOT_TREE_DIR_OBJECTID);
+	if (ret)
+		goto err;
+	memcpy(&location, &root->root_key, sizeof(location));
+	location.offset = (u64)-1;
+	ret = btrfs_insert_dir_item(trans, fs_info->tree_root, "default", 7,
+				btrfs_super_root_dir(&fs_info->super_copy),
+				&location, BTRFS_FT_DIR);
+	if (ret)
+		goto err;
+	ret = btrfs_insert_inode_ref(trans, fs_info->tree_root, "default", 7,
+				location.objectid,
+				btrfs_super_root_dir(&fs_info->super_copy));
+	if (ret)
+		goto err;
+	btrfs_set_root_dirid(&fs_info->fs_root->root_item,
+			     BTRFS_FIRST_FREE_OBJECTID);
+	ret = btrfs_commit_transaction(trans, root);
+	BUG_ON(ret);
+err:
+	return ret;
+}
+
+/*
+ * Migrate super block to it's default position.
+ * This function is dangerous, it modifies a block used by ext2fs.
+ */
+static int migrate_super_block(struct btrfs_root *root, u64 sb_offset)
+{
+	int ret = -1;
+	struct extent_buffer *old_eb;
+	struct extent_buffer *sb_buffer;
+	struct btrfs_trans_handle *trans;
+
+	BUG_ON(sb_offset != BTRFS_SUPER_INFO_OFFSET);
+	sb_buffer = read_tree_block(root, sb_offset, 512);
+	if (!sb_buffer)
+		goto fail;
+	memset_extent_buffer(sb_buffer, 0, 0, sb_buffer->len);
+	old_eb = root->fs_info->sb_buffer;
+	root->fs_info->sb_buffer = sb_buffer;
+	btrfs_set_super_bytenr(&root->fs_info->super_copy, sb_offset);
+	trans = btrfs_start_transaction(root, 1);
+	BUG_ON(!trans);
+	ret = btrfs_free_extent(trans, root, old_eb->start, root->leafsize,
+				0, 0, 0, 0, 1);
+	if (ret)
+		goto fail;
+	ret = btrfs_commit_transaction(trans, root);
+	free_extent_buffer(old_eb);
+	BUG_ON(ret);
+fail:
+	return ret;
+}
+
+int main(int argc, char *argv[])
+{
+	int i, fd, ret;
+	u32 blocksize;
+	u64 blocks[4];
+	u64 total_bytes;
+	u64 super_bytenr;
+	ext2_filsys ext2_fs;
+	struct btrfs_root *root;
+	struct btrfs_root *snap_root;
+
+	if (argc != 2) {
+		fprintf(stderr, "usage: %s device\n", argv[0]);
+		exit(1);
+	}
+	ret = open_ext2fs(argv[1], &ext2_fs);
+	if (ret) {
+		fprintf(stderr, "failed to open the Ext2fs\n");
+		goto fail;
+	}
+	blocksize = ext2_fs->blocksize;
+	total_bytes = (u64)ext2_fs->super->s_blocks_count * blocksize;
+	if (blocksize < 4096) {
+		fprintf(stderr, "block size is too small\n");
+		goto fail;
+	}
+	if (!(ext2_fs->super->s_feature_incompat &
+	      EXT2_FEATURE_INCOMPAT_FILETYPE)) {
+		fprintf(stderr, "missing filetype feature\n");
+		goto fail;
+	}
+	for (i = 0; i < 4; i++) {
+		ret = ext2_alloc_block(ext2_fs, 0, blocks + i);
+		if (ret) {
+			fprintf(stderr, "free space isn't enough\n");
+			goto fail;
+		}
+		blocks[i] *= blocksize;
+	}
+	super_bytenr = blocks[0];
+
+	fd = open(argv[1], O_RDWR);
+	if (fd < 0) {
+		fprintf(stderr, "unable to open %s\n", argv[1]);
+		goto fail;
+	}
+	ret = make_btrfs(fd, blocks, total_bytes, blocksize,
+			 blocksize, blocksize, blocksize);
+	if (ret) {
+		fprintf(stderr, "failed to create ctree\n");
+		goto fail;
+	}
+	root = open_ctree_fd(fd, super_bytenr);
+	if (!root) {
+		fprintf(stderr, "failed to open ctree\n");
+		goto fail;
+	}
+
+	root->fs_info->priv_data = ext2_fs;
+	root->fs_info->extent_ops = &extent_ops;
+
+	ret = init_btrfs(root);
+	if (ret) {
+		fprintf(stderr, "failed to setup the root tree\n");
+		goto fail;
+	}
+	snap_root = create_subvol(root, "ext2_saved", 10);
+	if (!snap_root) {
+		fprintf(stderr, "failed to create subvol\n");
+		goto fail;
+	}
+	printf("creating btrfs metadata.\n");
+	ret = copy_inodes(root, ext2_fs);
+	if (ret) {
+		fprintf(stderr, "error during copy_inodes %d\n", ret);
+		goto fail;
+	}
+	printf("creating ext2fs image file.\n");
+	ret = create_ext2_image(snap_root, "image", 5, ext2_fs);
+	if (ret) {
+		fprintf(stderr, "failed to create fs image\n");
+		goto fail;
+	}
+	ret = migrate_super_block(root, BTRFS_SUPER_INFO_OFFSET);
+	if (ret) {
+		fprintf(stderr, "failed to update super block\n");
+		goto fail;
+	}
+	btrfs_free_fs_root(snap_root->fs_info, snap_root);
+	ret = close_ctree(root);
+	if (ret) {
+		fprintf(stderr, "error during close_ctree %d\n", ret);
+		goto fail;
+	}
+	close_ext2fs(ext2_fs);
+	printf("conversion complete.\n");
+	exit(0);
+fail:
+	fprintf(stderr, "conversion abort.\n");
+	exit(1);
+}