fs/ext4/migrate.c - kernel/msm-4.9 - Gitiles

 /*
  * Copyright IBM Corporation, 2007
  * Author Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
  *
  * This program is free software; you can redistribute it and/or modify it
  * under the terms of version 2.1 of the GNU Lesser General Public License
  * as published by the Free Software Foundation.
  *
  * This program is distributed in the hope that it would be useful, but
  * WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
  *
  */

 #include <linux/module.h>
 #include <linux/ext4_jbd2.h>
 #include <linux/ext4_fs_extents.h>

 /*
  * The contiguous blocks details which can be
  * represented by a single extent
  */
 struct list_blocks_struct {
 	ext4_lblk_t first_block, last_block;
 	ext4_fsblk_t first_pblock, last_pblock;
 };

 static int finish_range(handle_t *handle, struct inode *inode,
 				struct list_blocks_struct *lb)

 {
 	int retval = 0, needed;
 	struct ext4_extent newext;
 	struct ext4_ext_path *path;
 	if (lb->first_pblock == 0)
 		return 0;

 	/* Add the extent to temp inode*/
 	newext.ee_block = cpu_to_le32(lb->first_block);
 	newext.ee_len   = cpu_to_le16(lb->last_block - lb->first_block + 1);
 	ext4_ext_store_pblock(&newext, lb->first_pblock);
 	path = ext4_ext_find_extent(inode, lb->first_block, NULL);

 	if (IS_ERR(path)) {
 		retval = PTR_ERR(path);
 		goto err_out;
 	}

 	/*
 	 * Calculate the credit needed to inserting this extent
 	 * Since we are doing this in loop we may accumalate extra
 	 * credit. But below we try to not accumalate too much
 	 * of them by restarting the journal.
 	 */
 	needed = ext4_ext_calc_credits_for_insert(inode, path);

 	/*
 	 * Make sure the credit we accumalated is not really high
 	 */
 	if (needed && handle->h_buffer_credits >= EXT4_RESERVE_TRANS_BLOCKS) {
 		retval = ext4_journal_restart(handle, needed);
 		if (retval)
 			goto err_out;
 	}
 	if (needed) {
 		retval = ext4_journal_extend(handle, needed);
 		if (retval != 0) {
 			/*
 			 * IF not able to extend the journal restart the journal
 			 */
 			retval = ext4_journal_restart(handle, needed);
 			if (retval)
 				goto err_out;
 		}
 	}
 	retval = ext4_ext_insert_extent(handle, inode, path, &newext);
 err_out:
 	lb->first_pblock = 0;
 	return retval;
 }

 static int update_extent_range(handle_t *handle, struct inode *inode,
 				ext4_fsblk_t pblock, ext4_lblk_t blk_num,
 				struct list_blocks_struct *lb)
 {
 	int retval;
 	/*
 	 * See if we can add on to the existing range (if it exists)
 	 */
 	if (lb->first_pblock &&
 		(lb->last_pblock+1 == pblock) &&
 		(lb->last_block+1 == blk_num)) {
 		lb->last_pblock = pblock;
 		lb->last_block = blk_num;
 		return 0;
 	}
 	/*
 	 * Start a new range.
 	 */
 	retval = finish_range(handle, inode, lb);
 	lb->first_pblock = lb->last_pblock = pblock;
 	lb->first_block = lb->last_block = blk_num;

 	return retval;
 }

 static int update_ind_extent_range(handle_t *handle, struct inode *inode,
 				   ext4_fsblk_t pblock, ext4_lblk_t *blk_nump,
 				   struct list_blocks_struct *lb)
 {
 	struct buffer_head *bh;
 	__le32 *i_data;
 	int i, retval = 0;
 	ext4_lblk_t blk_count = *blk_nump;
 	unsigned long max_entries = inode->i_sb->s_blocksize >> 2;

 	if (!pblock) {
 		/* Only update the file block number */
 		*blk_nump += max_entries;
 		return 0;
 	}

 	bh = sb_bread(inode->i_sb, pblock);
 	if (!bh)
 		return -EIO;

 	i_data = (__le32 *)bh->b_data;
 	for (i = 0; i < max_entries; i++, blk_count++) {
 		if (i_data[i]) {
 			retval = update_extent_range(handle, inode,
 						le32_to_cpu(i_data[i]),
 						blk_count, lb);
 			if (retval)
 				break;
 		}
 	}

 	/* Update the file block number */
 	*blk_nump = blk_count;
 	put_bh(bh);
 	return retval;

 }

 static int update_dind_extent_range(handle_t *handle, struct inode *inode,
 				    ext4_fsblk_t pblock, ext4_lblk_t *blk_nump,
 				    struct list_blocks_struct *lb)
 {
 	struct buffer_head *bh;
 	__le32 *i_data;
 	int i, retval = 0;
 	ext4_lblk_t blk_count = *blk_nump;
 	unsigned long max_entries = inode->i_sb->s_blocksize >> 2;

 	if (!pblock) {
 		/* Only update the file block number */
 		*blk_nump += max_entries * max_entries;
 		return 0;
 	}
 	bh = sb_bread(inode->i_sb, pblock);
 	if (!bh)
 		return -EIO;

 	i_data = (__le32 *)bh->b_data;
 	for (i = 0; i < max_entries; i++) {
 		if (i_data[i]) {
 			retval = update_ind_extent_range(handle, inode,
 						le32_to_cpu(i_data[i]),
 						&blk_count, lb);
 			if (retval)
 				break;
 		} else {
 			/* Only update the file block number */
 			blk_count += max_entries;
 		}
 	}

 	/* Update the file block number */
 	*blk_nump = blk_count;
 	put_bh(bh);
 	return retval;

 }

 static int update_tind_extent_range(handle_t *handle, struct inode *inode,
 				     ext4_fsblk_t pblock, ext4_lblk_t *blk_nump,
 				     struct list_blocks_struct *lb)
 {
 	struct buffer_head *bh;
 	__le32 *i_data;
 	int i, retval = 0;
 	ext4_lblk_t blk_count = *blk_nump;
 	unsigned long max_entries = inode->i_sb->s_blocksize >> 2;

 	if (!pblock) {
 		/* Only update the file block number */
 		*blk_nump += max_entries * max_entries * max_entries;
 		return 0;
 	}
 	bh = sb_bread(inode->i_sb, pblock);
 	if (!bh)
 		return -EIO;

 	i_data = (__le32 *)bh->b_data;
 	for (i = 0; i < max_entries; i++) {
 		if (i_data[i]) {
 			retval = update_dind_extent_range(handle, inode,
 						le32_to_cpu(i_data[i]),
 						&blk_count, lb);
 			if (retval)
 				break;
 		} else
 			/* Only update the file block number */
 			blk_count += max_entries * max_entries;
 	}
 	/* Update the file block number */
 	*blk_nump = blk_count;
 	put_bh(bh);
 	return retval;

 }

 static int free_dind_blocks(handle_t *handle,
 				struct inode *inode, __le32 i_data)
 {
 	int i;
 	__le32 *tmp_idata;
 	struct buffer_head *bh;
 	unsigned long max_entries = inode->i_sb->s_blocksize >> 2;

 	bh = sb_bread(inode->i_sb, le32_to_cpu(i_data));
 	if (!bh)
 		return -EIO;

 	tmp_idata = (__le32 *)bh->b_data;
 	for (i = 0; i < max_entries; i++) {
 		if (tmp_idata[i])
 			ext4_free_blocks(handle, inode,
 					le32_to_cpu(tmp_idata[i]), 1, 1);
 	}
 	put_bh(bh);
 	ext4_free_blocks(handle, inode, le32_to_cpu(i_data), 1, 1);
 	return 0;
 }

 static int free_tind_blocks(handle_t *handle,
 				struct inode *inode, __le32 i_data)
 {
 	int i, retval = 0;
 	__le32 *tmp_idata;
 	struct buffer_head *bh;
 	unsigned long max_entries = inode->i_sb->s_blocksize >> 2;

 	bh = sb_bread(inode->i_sb, le32_to_cpu(i_data));
 	if (!bh)
 		return -EIO;

 	tmp_idata = (__le32 *)bh->b_data;
 	for (i = 0; i < max_entries; i++) {
 		if (tmp_idata[i]) {
 			retval = free_dind_blocks(handle,
 					inode, tmp_idata[i]);
 			if (retval) {
 				put_bh(bh);
 				return retval;
 			}
 		}
 	}
 	put_bh(bh);
 	ext4_free_blocks(handle, inode, le32_to_cpu(i_data), 1, 1);
 	return 0;
 }

 static int free_ind_block(handle_t *handle, struct inode *inode)
 {
 	int retval;
 	struct ext4_inode_info *ei = EXT4_I(inode);

 	if (ei->i_data[EXT4_IND_BLOCK])
 		ext4_free_blocks(handle, inode,
 				le32_to_cpu(ei->i_data[EXT4_IND_BLOCK]), 1, 1);

 	if (ei->i_data[EXT4_DIND_BLOCK]) {
 		retval = free_dind_blocks(handle, inode,
 						ei->i_data[EXT4_DIND_BLOCK]);
 		if (retval)
 			return retval;
 	}

 	if (ei->i_data[EXT4_TIND_BLOCK]) {
 		retval = free_tind_blocks(handle, inode,
 						ei->i_data[EXT4_TIND_BLOCK]);
 		if (retval)
 			return retval;
 	}
 	return 0;
 }

 static int ext4_ext_swap_inode_data(handle_t *handle, struct inode *inode,
 				struct inode *tmp_inode, int retval)
 {
 	struct ext4_inode_info *ei = EXT4_I(inode);
 	struct ext4_inode_info *tmp_ei = EXT4_I(tmp_inode);

 	retval = free_ind_block(handle, inode);
 	if (retval)
 		goto err_out;

 	/*
 	 * One credit accounted for writing the
 	 * i_data field of the original inode
 	 */
 	retval = ext4_journal_extend(handle, 1);
 	if (retval != 0) {
 		retval = ext4_journal_restart(handle, 1);
 		if (retval)
 			goto err_out;
 	}

 	/*
 	 * We have the extent map build with the tmp inode.
 	 * Now copy the i_data across
 	 */
 	ei->i_flags |= EXT4_EXTENTS_FL;
 	memcpy(ei->i_data, tmp_ei->i_data, sizeof(ei->i_data));

 	/*
 	 * Update i_blocks with the new blocks that got
 	 * allocated while adding extents for extent index
 	 * blocks.
 	 *
 	 * While converting to extents we need not
 	 * update the orignal inode i_blocks for extent blocks
 	 * via quota APIs. The quota update happened via tmp_inode already.
 	 */
 	spin_lock(&inode->i_lock);
 	inode->i_blocks += tmp_inode->i_blocks;
 	spin_unlock(&inode->i_lock);

 	ext4_mark_inode_dirty(handle, inode);
 err_out:
 	return retval;
 }

 static int free_ext_idx(handle_t *handle, struct inode *inode,
 					struct ext4_extent_idx *ix)
 {
 	int i, retval = 0;
 	ext4_fsblk_t block;
 	struct buffer_head *bh;
 	struct ext4_extent_header *eh;

 	block = idx_pblock(ix);
 	bh = sb_bread(inode->i_sb, block);
 	if (!bh)
 		return -EIO;

 	eh = (struct ext4_extent_header *)bh->b_data;
 	if (eh->eh_depth != 0) {
 		ix = EXT_FIRST_INDEX(eh);
 		for (i = 0; i < le16_to_cpu(eh->eh_entries); i++, ix++) {
 			retval = free_ext_idx(handle, inode, ix);
 			if (retval)
 				break;
 		}
 	}
 	put_bh(bh);
 	ext4_free_blocks(handle, inode, block, 1, 1);
 	return retval;
 }

 /*
  * Free the extent meta data blocks only
  */
 static int free_ext_block(handle_t *handle, struct inode *inode)
 {
 	int i, retval = 0;
 	struct ext4_inode_info *ei = EXT4_I(inode);
 	struct ext4_extent_header *eh = (struct ext4_extent_header *)ei->i_data;
 	struct ext4_extent_idx *ix;
 	if (eh->eh_depth == 0)
 		/*
 		 * No extra blocks allocated for extent meta data
 		 */
 		return 0;
 	ix = EXT_FIRST_INDEX(eh);
 	for (i = 0; i < le16_to_cpu(eh->eh_entries); i++, ix++) {
 		retval = free_ext_idx(handle, inode, ix);
 		if (retval)
 			return retval;
 	}
 	return retval;

 }

 int ext4_ext_migrate(struct inode *inode, struct file *filp,
 				unsigned int cmd, unsigned long arg)
 {
 	handle_t *handle;
 	int retval = 0, i;
 	__le32 *i_data;
 	ext4_lblk_t blk_count = 0;
 	struct ext4_inode_info *ei;
 	struct inode *tmp_inode = NULL;
 	struct list_blocks_struct lb;
 	unsigned long max_entries;

 	if (!test_opt(inode->i_sb, EXTENTS))
 		/*
 		 * if mounted with noextents we don't allow the migrate
 		 */
 		return -EINVAL;

 	if ((EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL))
 		return -EINVAL;

 	down_write(&EXT4_I(inode)->i_data_sem);
 	handle = ext4_journal_start(inode,
 					EXT4_DATA_TRANS_BLOCKS(inode->i_sb) +
 					EXT4_INDEX_EXTRA_TRANS_BLOCKS + 3 +
 					2 * EXT4_QUOTA_INIT_BLOCKS(inode->i_sb)
 					+ 1);
 	if (IS_ERR(handle)) {
 		retval = PTR_ERR(handle);
 		goto err_out;
 	}
 	tmp_inode = ext4_new_inode(handle,
 				inode->i_sb->s_root->d_inode,
 				S_IFREG);
 	if (IS_ERR(tmp_inode)) {
 		retval = -ENOMEM;
 		ext4_journal_stop(handle);
 		tmp_inode = NULL;
 		goto err_out;
 	}
 	i_size_write(tmp_inode, i_size_read(inode));
 	/*
 	 * We don't want the inode to be reclaimed
 	 * if we got interrupted in between. We have
 	 * this tmp inode carrying reference to the
 	 * data blocks of the original file. We set
 	 * the i_nlink to zero at the last stage after
 	 * switching the original file to extent format
 	 */
 	tmp_inode->i_nlink = 1;

 	ext4_ext_tree_init(handle, tmp_inode);
 	ext4_orphan_add(handle, tmp_inode);
 	ext4_journal_stop(handle);

 	ei = EXT4_I(inode);
 	i_data = ei->i_data;
 	memset(&lb, 0, sizeof(lb));

 	/* 32 bit block address 4 bytes */
 	max_entries = inode->i_sb->s_blocksize >> 2;

 	/*
 	 * start with one credit accounted for
 	 * superblock modification.
 	 *
 	 * For the tmp_inode we already have commited the
 	 * trascation that created the inode. Later as and
 	 * when we add extents we extent the journal
 	 */
 	handle = ext4_journal_start(inode, 1);
 	for (i = 0; i < EXT4_NDIR_BLOCKS; i++, blk_count++) {
 		if (i_data[i]) {
 			retval = update_extent_range(handle, tmp_inode,
 						le32_to_cpu(i_data[i]),
 						blk_count, &lb);
 			if (retval)
 				goto err_out;
 		}
 	}
 	if (i_data[EXT4_IND_BLOCK]) {
 		retval = update_ind_extent_range(handle, tmp_inode,
 					le32_to_cpu(i_data[EXT4_IND_BLOCK]),
 					&blk_count, &lb);
 			if (retval)
 				goto err_out;
 	} else
 		blk_count +=  max_entries;
 	if (i_data[EXT4_DIND_BLOCK]) {
 		retval = update_dind_extent_range(handle, tmp_inode,
 					le32_to_cpu(i_data[EXT4_DIND_BLOCK]),
 					&blk_count, &lb);
 			if (retval)
 				goto err_out;
 	} else
 		blk_count += max_entries * max_entries;
 	if (i_data[EXT4_TIND_BLOCK]) {
 		retval = update_tind_extent_range(handle, tmp_inode,
 					le32_to_cpu(i_data[EXT4_TIND_BLOCK]),
 					&blk_count, &lb);
 			if (retval)
 				goto err_out;
 	}
 	/*
 	 * Build the last extent
 	 */
 	retval = finish_range(handle, tmp_inode, &lb);
 err_out:
 	/*
 	 * We are either freeing extent information or indirect
 	 * blocks. During this we touch superblock, group descriptor
 	 * and block bitmap. Later we mark the tmp_inode dirty
 	 * via ext4_ext_tree_init. So allocate a credit of 4
 	 * We may update quota (user and group).
 	 *
 	 * FIXME!! we may be touching bitmaps in different block groups.
 	 */
 	if (ext4_journal_extend(handle,
 			4 + 2*EXT4_QUOTA_TRANS_BLOCKS(inode->i_sb)) != 0)
 		ext4_journal_restart(handle,
 				4 + 2*EXT4_QUOTA_TRANS_BLOCKS(inode->i_sb));
 	if (retval)
 		/*
 		 * Failure case delete the extent information with the
 		 * tmp_inode
 		 */
 		free_ext_block(handle, tmp_inode);
 	else
 		retval = ext4_ext_swap_inode_data(handle, inode,
 							tmp_inode, retval);

 	/*
 	 * Mark the tmp_inode as of size zero
 	 */
 	i_size_write(tmp_inode, 0);

 	/*
 	 * set the  i_blocks count to zero
 	 * so that the ext4_delete_inode does the
 	 * right job
 	 *
 	 * We don't need to take the i_lock because
 	 * the inode is not visible to user space.
 	 */
 	tmp_inode->i_blocks = 0;

 	/* Reset the extent details */
 	ext4_ext_tree_init(handle, tmp_inode);

 	/*
 	 * Set the i_nlink to zero so that
 	 * generic_drop_inode really deletes the
 	 * inode
 	 */
 	tmp_inode->i_nlink = 0;

 	ext4_journal_stop(handle);

 	up_write(&EXT4_I(inode)->i_data_sem);

 	if (tmp_inode)
 		iput(tmp_inode);

 	return retval;
 }
	/*
	* Copyright IBM Corporation, 2007
	* Author Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
	*
	* This program is free software; you can redistribute it and/or modify it
	* under the terms of version 2.1 of the GNU Lesser General Public License
	* as published by the Free Software Foundation.
	*
	* This program is distributed in the hope that it would be useful, but
	* WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
	*
	*/

	#include <linux/module.h>
	#include <linux/ext4_jbd2.h>
	#include <linux/ext4_fs_extents.h>

	/*
	* The contiguous blocks details which can be
	* represented by a single extent
	*/
	struct list_blocks_struct {
	ext4_lblk_t first_block, last_block;
	ext4_fsblk_t first_pblock, last_pblock;
	};

	static int finish_range(handle_t handle, struct inode inode,
	struct list_blocks_struct *lb)

	{
	int retval = 0, needed;
	struct ext4_extent newext;
	struct ext4_ext_path *path;
	if (lb->first_pblock == 0)
	return 0;

	/* Add the extent to temp inode*/
	newext.ee_block = cpu_to_le32(lb->first_block);
	newext.ee_len = cpu_to_le16(lb->last_block - lb->first_block + 1);
	ext4_ext_store_pblock(&newext, lb->first_pblock);
	path = ext4_ext_find_extent(inode, lb->first_block, NULL);

	if (IS_ERR(path)) {
	retval = PTR_ERR(path);
	goto err_out;
	}

	/*
	* Calculate the credit needed to inserting this extent
	* Since we are doing this in loop we may accumalate extra
	* credit. But below we try to not accumalate too much
	* of them by restarting the journal.
	*/
	needed = ext4_ext_calc_credits_for_insert(inode, path);

	/*
	* Make sure the credit we accumalated is not really high
	*/
	if (needed && handle->h_buffer_credits >= EXT4_RESERVE_TRANS_BLOCKS) {
	retval = ext4_journal_restart(handle, needed);
	if (retval)
	goto err_out;
	}
	if (needed) {
	retval = ext4_journal_extend(handle, needed);
	if (retval != 0) {
	/*
	* IF not able to extend the journal restart the journal
	*/
	retval = ext4_journal_restart(handle, needed);
	if (retval)
	goto err_out;
	}
	}
	retval = ext4_ext_insert_extent(handle, inode, path, &newext);
	err_out:
	lb->first_pblock = 0;
	return retval;
	}

	static int update_extent_range(handle_t handle, struct inode inode,
	ext4_fsblk_t pblock, ext4_lblk_t blk_num,
	struct list_blocks_struct *lb)
	{
	int retval;
	/*
	* See if we can add on to the existing range (if it exists)
	*/
	if (lb->first_pblock &&
	(lb->last_pblock+1 == pblock) &&
	(lb->last_block+1 == blk_num)) {
	lb->last_pblock = pblock;
	lb->last_block = blk_num;
	return 0;
	}
	/*
	* Start a new range.
	*/
	retval = finish_range(handle, inode, lb);
	lb->first_pblock = lb->last_pblock = pblock;
	lb->first_block = lb->last_block = blk_num;

	return retval;
	}

	static int update_ind_extent_range(handle_t handle, struct inode inode,
	ext4_fsblk_t pblock, ext4_lblk_t *blk_nump,
	struct list_blocks_struct *lb)
	{
	struct buffer_head *bh;
	__le32 *i_data;
	int i, retval = 0;
	ext4_lblk_t blk_count = *blk_nump;
	unsigned long max_entries = inode->i_sb->s_blocksize >> 2;

	if (!pblock) {
	/* Only update the file block number */
	*blk_nump += max_entries;
	return 0;
	}

	bh = sb_bread(inode->i_sb, pblock);
	if (!bh)
	return -EIO;

	i_data = (__le32 *)bh->b_data;
	for (i = 0; i < max_entries; i++, blk_count++) {
	if (i_data[i]) {
	retval = update_extent_range(handle, inode,
	le32_to_cpu(i_data[i]),
	blk_count, lb);
	if (retval)
	break;
	}
	}

	/* Update the file block number */
	*blk_nump = blk_count;
	put_bh(bh);
	return retval;

	}

	static int update_dind_extent_range(handle_t handle, struct inode inode,
	ext4_fsblk_t pblock, ext4_lblk_t *blk_nump,
	struct list_blocks_struct *lb)
	{
	struct buffer_head *bh;
	__le32 *i_data;
	int i, retval = 0;
	ext4_lblk_t blk_count = *blk_nump;
	unsigned long max_entries = inode->i_sb->s_blocksize >> 2;

	if (!pblock) {
	/* Only update the file block number */
	blk_nump += max_entries max_entries;
	return 0;
	}
	bh = sb_bread(inode->i_sb, pblock);
	if (!bh)
	return -EIO;

	i_data = (__le32 *)bh->b_data;
	for (i = 0; i < max_entries; i++) {
	if (i_data[i]) {
	retval = update_ind_extent_range(handle, inode,
	le32_to_cpu(i_data[i]),
	&blk_count, lb);
	if (retval)
	break;
	} else {
	/* Only update the file block number */
	blk_count += max_entries;
	}
	}

	/* Update the file block number */
	*blk_nump = blk_count;
	put_bh(bh);
	return retval;

	}

	static int update_tind_extent_range(handle_t handle, struct inode inode,
	ext4_fsblk_t pblock, ext4_lblk_t *blk_nump,
	struct list_blocks_struct *lb)
	{
	struct buffer_head *bh;
	__le32 *i_data;
	int i, retval = 0;
	ext4_lblk_t blk_count = *blk_nump;
	unsigned long max_entries = inode->i_sb->s_blocksize >> 2;

	if (!pblock) {
	/* Only update the file block number */
	blk_nump += max_entries max_entries * max_entries;
	return 0;
	}
	bh = sb_bread(inode->i_sb, pblock);
	if (!bh)
	return -EIO;

	i_data = (__le32 *)bh->b_data;
	for (i = 0; i < max_entries; i++) {
	if (i_data[i]) {
	retval = update_dind_extent_range(handle, inode,
	le32_to_cpu(i_data[i]),
	&blk_count, lb);
	if (retval)
	break;
	} else
	/* Only update the file block number */
	blk_count += max_entries * max_entries;
	}
	/* Update the file block number */
	*blk_nump = blk_count;
	put_bh(bh);
	return retval;

	}

	static int free_dind_blocks(handle_t *handle,
	struct inode *inode, __le32 i_data)
	{
	int i;
	__le32 *tmp_idata;
	struct buffer_head *bh;
	unsigned long max_entries = inode->i_sb->s_blocksize >> 2;

	bh = sb_bread(inode->i_sb, le32_to_cpu(i_data));
	if (!bh)
	return -EIO;

	tmp_idata = (__le32 *)bh->b_data;
	for (i = 0; i < max_entries; i++) {
	if (tmp_idata[i])
	ext4_free_blocks(handle, inode,
	le32_to_cpu(tmp_idata[i]), 1, 1);
	}
	put_bh(bh);
	ext4_free_blocks(handle, inode, le32_to_cpu(i_data), 1, 1);
	return 0;
	}

	static int free_tind_blocks(handle_t *handle,
	struct inode *inode, __le32 i_data)
	{
	int i, retval = 0;
	__le32 *tmp_idata;
	struct buffer_head *bh;
	unsigned long max_entries = inode->i_sb->s_blocksize >> 2;

	bh = sb_bread(inode->i_sb, le32_to_cpu(i_data));
	if (!bh)
	return -EIO;

	tmp_idata = (__le32 *)bh->b_data;
	for (i = 0; i < max_entries; i++) {
	if (tmp_idata[i]) {
	retval = free_dind_blocks(handle,
	inode, tmp_idata[i]);
	if (retval) {
	put_bh(bh);
	return retval;
	}
	}
	}
	put_bh(bh);
	ext4_free_blocks(handle, inode, le32_to_cpu(i_data), 1, 1);
	return 0;
	}

	static int free_ind_block(handle_t handle, struct inode inode)
	{
	int retval;
	struct ext4_inode_info *ei = EXT4_I(inode);

	if (ei->i_data[EXT4_IND_BLOCK])
	ext4_free_blocks(handle, inode,
	le32_to_cpu(ei->i_data[EXT4_IND_BLOCK]), 1, 1);

	if (ei->i_data[EXT4_DIND_BLOCK]) {
	retval = free_dind_blocks(handle, inode,
	ei->i_data[EXT4_DIND_BLOCK]);
	if (retval)
	return retval;
	}

	if (ei->i_data[EXT4_TIND_BLOCK]) {
	retval = free_tind_blocks(handle, inode,
	ei->i_data[EXT4_TIND_BLOCK]);
	if (retval)
	return retval;
	}
	return 0;
	}

	static int ext4_ext_swap_inode_data(handle_t handle, struct inode inode,
	struct inode *tmp_inode, int retval)
	{
	struct ext4_inode_info *ei = EXT4_I(inode);
	struct ext4_inode_info *tmp_ei = EXT4_I(tmp_inode);

	retval = free_ind_block(handle, inode);
	if (retval)
	goto err_out;

	/*
	* One credit accounted for writing the
	* i_data field of the original inode
	*/
	retval = ext4_journal_extend(handle, 1);
	if (retval != 0) {
	retval = ext4_journal_restart(handle, 1);
	if (retval)
	goto err_out;
	}

	/*
	* We have the extent map build with the tmp inode.
	* Now copy the i_data across
	*/
	ei->i_flags \|= EXT4_EXTENTS_FL;
	memcpy(ei->i_data, tmp_ei->i_data, sizeof(ei->i_data));

	/*
	* Update i_blocks with the new blocks that got
	* allocated while adding extents for extent index
	* blocks.
	*
	* While converting to extents we need not
	* update the orignal inode i_blocks for extent blocks
	* via quota APIs. The quota update happened via tmp_inode already.
	*/
	spin_lock(&inode->i_lock);
	inode->i_blocks += tmp_inode->i_blocks;
	spin_unlock(&inode->i_lock);

	ext4_mark_inode_dirty(handle, inode);
	err_out:
	return retval;
	}

	static int free_ext_idx(handle_t handle, struct inode inode,
	struct ext4_extent_idx *ix)
	{
	int i, retval = 0;
	ext4_fsblk_t block;
	struct buffer_head *bh;
	struct ext4_extent_header *eh;

	block = idx_pblock(ix);
	bh = sb_bread(inode->i_sb, block);
	if (!bh)
	return -EIO;

	eh = (struct ext4_extent_header *)bh->b_data;
	if (eh->eh_depth != 0) {
	ix = EXT_FIRST_INDEX(eh);
	for (i = 0; i < le16_to_cpu(eh->eh_entries); i++, ix++) {
	retval = free_ext_idx(handle, inode, ix);
	if (retval)
	break;
	}
	}
	put_bh(bh);
	ext4_free_blocks(handle, inode, block, 1, 1);
	return retval;
	}

	/*
	* Free the extent meta data blocks only
	*/
	static int free_ext_block(handle_t handle, struct inode inode)
	{
	int i, retval = 0;
	struct ext4_inode_info *ei = EXT4_I(inode);
	struct ext4_extent_header eh = (struct ext4_extent_header )ei->i_data;
	struct ext4_extent_idx *ix;
	if (eh->eh_depth == 0)
	/*
	* No extra blocks allocated for extent meta data
	*/
	return 0;
	ix = EXT_FIRST_INDEX(eh);
	for (i = 0; i < le16_to_cpu(eh->eh_entries); i++, ix++) {
	retval = free_ext_idx(handle, inode, ix);
	if (retval)
	return retval;
	}
	return retval;

	}

	int ext4_ext_migrate(struct inode inode, struct file filp,
	unsigned int cmd, unsigned long arg)
	{
	handle_t *handle;
	int retval = 0, i;
	__le32 *i_data;
	ext4_lblk_t blk_count = 0;
	struct ext4_inode_info *ei;
	struct inode *tmp_inode = NULL;
	struct list_blocks_struct lb;
	unsigned long max_entries;

	if (!test_opt(inode->i_sb, EXTENTS))
	/*
	* if mounted with noextents we don't allow the migrate
	*/
	return -EINVAL;

	if ((EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL))
	return -EINVAL;

	down_write(&EXT4_I(inode)->i_data_sem);
	handle = ext4_journal_start(inode,
	EXT4_DATA_TRANS_BLOCKS(inode->i_sb) +
	EXT4_INDEX_EXTRA_TRANS_BLOCKS + 3 +
	2 * EXT4_QUOTA_INIT_BLOCKS(inode->i_sb)
	+ 1);
	if (IS_ERR(handle)) {
	retval = PTR_ERR(handle);
	goto err_out;
	}
	tmp_inode = ext4_new_inode(handle,
	inode->i_sb->s_root->d_inode,
	S_IFREG);
	if (IS_ERR(tmp_inode)) {
	retval = -ENOMEM;
	ext4_journal_stop(handle);
	tmp_inode = NULL;
	goto err_out;
	}
	i_size_write(tmp_inode, i_size_read(inode));
	/*
	* We don't want the inode to be reclaimed
	* if we got interrupted in between. We have
	* this tmp inode carrying reference to the
	* data blocks of the original file. We set
	* the i_nlink to zero at the last stage after
	* switching the original file to extent format
	*/
	tmp_inode->i_nlink = 1;

	ext4_ext_tree_init(handle, tmp_inode);
	ext4_orphan_add(handle, tmp_inode);
	ext4_journal_stop(handle);

	ei = EXT4_I(inode);
	i_data = ei->i_data;
	memset(&lb, 0, sizeof(lb));

	/* 32 bit block address 4 bytes */
	max_entries = inode->i_sb->s_blocksize >> 2;

	/*
	* start with one credit accounted for
	* superblock modification.
	*
	* For the tmp_inode we already have commited the
	* trascation that created the inode. Later as and
	* when we add extents we extent the journal
	*/
	handle = ext4_journal_start(inode, 1);
	for (i = 0; i < EXT4_NDIR_BLOCKS; i++, blk_count++) {
	if (i_data[i]) {
	retval = update_extent_range(handle, tmp_inode,
	le32_to_cpu(i_data[i]),
	blk_count, &lb);
	if (retval)
	goto err_out;
	}
	}
	if (i_data[EXT4_IND_BLOCK]) {
	retval = update_ind_extent_range(handle, tmp_inode,
	le32_to_cpu(i_data[EXT4_IND_BLOCK]),
	&blk_count, &lb);
	if (retval)
	goto err_out;
	} else
	blk_count += max_entries;
	if (i_data[EXT4_DIND_BLOCK]) {
	retval = update_dind_extent_range(handle, tmp_inode,
	le32_to_cpu(i_data[EXT4_DIND_BLOCK]),
	&blk_count, &lb);
	if (retval)
	goto err_out;
	} else
	blk_count += max_entries * max_entries;
	if (i_data[EXT4_TIND_BLOCK]) {
	retval = update_tind_extent_range(handle, tmp_inode,
	le32_to_cpu(i_data[EXT4_TIND_BLOCK]),
	&blk_count, &lb);
	if (retval)
	goto err_out;
	}
	/*
	* Build the last extent
	*/
	retval = finish_range(handle, tmp_inode, &lb);
	err_out:
	/*
	* We are either freeing extent information or indirect
	* blocks. During this we touch superblock, group descriptor
	* and block bitmap. Later we mark the tmp_inode dirty
	* via ext4_ext_tree_init. So allocate a credit of 4
	* We may update quota (user and group).
	*
	* FIXME!! we may be touching bitmaps in different block groups.
	*/
	if (ext4_journal_extend(handle,
	4 + 2*EXT4_QUOTA_TRANS_BLOCKS(inode->i_sb)) != 0)
	ext4_journal_restart(handle,
	4 + 2*EXT4_QUOTA_TRANS_BLOCKS(inode->i_sb));
	if (retval)
	/*
	* Failure case delete the extent information with the
	* tmp_inode
	*/
	free_ext_block(handle, tmp_inode);
	else
	retval = ext4_ext_swap_inode_data(handle, inode,
	tmp_inode, retval);

	/*
	* Mark the tmp_inode as of size zero
	*/
	i_size_write(tmp_inode, 0);

	/*
	* set the i_blocks count to zero
	* so that the ext4_delete_inode does the
	* right job
	*
	* We don't need to take the i_lock because
	* the inode is not visible to user space.
	*/
	tmp_inode->i_blocks = 0;

	/* Reset the extent details */
	ext4_ext_tree_init(handle, tmp_inode);

	/*
	* Set the i_nlink to zero so that
	* generic_drop_inode really deletes the
	* inode
	*/
	tmp_inode->i_nlink = 0;

	ext4_journal_stop(handle);

	up_write(&EXT4_I(inode)->i_data_sem);

	if (tmp_inode)
	iput(tmp_inode);

	return retval;
	}