/*
   * 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/slab.h>

  #include "ext4_jbd2.h"

  
  /*
   * The contiguous blocks details which can be
   * represented by a single extent
   */

  struct migrate_struct {
  	ext4_lblk_t first_block, last_block, curr_block;

  	ext4_fsblk_t first_pblock, last_pblock;
  };
  
  static int finish_range(handle_t *handle, struct inode *inode,

  				struct migrate_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);

  		path = NULL;

  		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_single_extent(inode,
  		    lb->last_block - lb->first_block + 1, path);

  
  	/*
  	 * Make sure the credit we accumalated is not really high
  	 */

  	if (needed && ext4_handle_has_enough_credits(handle,
  						EXT4_RESERVE_TRANS_BLOCKS)) {

  		retval = ext4_journal_restart(handle, needed);
  		if (retval)
  			goto err_out;

  	} else if (needed) {

  		retval = ext4_journal_extend(handle, needed);

  		if (retval) {

  			/*
  			 * 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, 0);

  err_out:

  	if (path) {
  		ext4_ext_drop_refs(path);
  		kfree(path);
  	}

  	lb->first_pblock = 0;
  	return retval;
  }
  
  static int update_extent_range(handle_t *handle, struct inode *inode,

  			       ext4_fsblk_t pblock, struct migrate_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 == lb->curr_block)) {

  		lb->last_pblock = pblock;

  		lb->last_block = lb->curr_block;
  		lb->curr_block++;

  		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 = lb->curr_block;
  	lb->curr_block++;

  	return retval;
  }
  
  static int update_ind_extent_range(handle_t *handle, struct inode *inode,

  				   ext4_fsblk_t pblock,
  				   struct migrate_struct *lb)

  {
  	struct buffer_head *bh;
  	__le32 *i_data;
  	int i, retval = 0;

  	unsigned long max_entries = inode->i_sb->s_blocksize >> 2;

  	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_extent_range(handle, inode,

  						le32_to_cpu(i_data[i]), lb);

  			if (retval)
  				break;

  		} else {
  			lb->curr_block++;

  		}
  	}

  	put_bh(bh);
  	return retval;
  
  }
  
  static int update_dind_extent_range(handle_t *handle, struct inode *inode,

  				    ext4_fsblk_t pblock,
  				    struct migrate_struct *lb)

  {
  	struct buffer_head *bh;
  	__le32 *i_data;
  	int i, retval = 0;

  	unsigned long max_entries = inode->i_sb->s_blocksize >> 2;

  	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]), lb);

  			if (retval)
  				break;
  		} else {
  			/* Only update the file block number */

  			lb->curr_block += max_entries;

  		}
  	}

  	put_bh(bh);
  	return retval;
  
  }
  
  static int update_tind_extent_range(handle_t *handle, struct inode *inode,

  				    ext4_fsblk_t pblock,
  				    struct migrate_struct *lb)

  {
  	struct buffer_head *bh;
  	__le32 *i_data;
  	int i, retval = 0;

  	unsigned long max_entries = inode->i_sb->s_blocksize >> 2;

  	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]), lb);

  			if (retval)
  				break;

  		} else {

  			/* Only update the file block number */

  			lb->curr_block += max_entries * max_entries;
  		}

  	}

  	put_bh(bh);
  	return retval;
  
  }

  static int extend_credit_for_blkdel(handle_t *handle, struct inode *inode)
  {
  	int retval = 0, needed;

  	if (ext4_handle_has_enough_credits(handle, EXT4_RESERVE_TRANS_BLOCKS+1))

  		return 0;
  	/*
  	 * We are freeing a blocks. During this we touch
  	 * superblock, group descriptor and block bitmap.
  	 * So allocate a credit of 3. We may update
  	 * quota (user and group).
  	 */

  	needed = 3 + EXT4_MAXQUOTAS_TRANS_BLOCKS(inode->i_sb);

  
  	if (ext4_journal_extend(handle, needed) != 0)
  		retval = ext4_journal_restart(handle, needed);
  
  	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]) {
  			extend_credit_for_blkdel(handle, inode);

  			ext4_free_blocks(handle, inode, NULL,

  					 le32_to_cpu(tmp_idata[i]), 1,
  					 EXT4_FREE_BLOCKS_METADATA |
  					 EXT4_FREE_BLOCKS_FORGET);

  		}

  	}
  	put_bh(bh);

  	extend_credit_for_blkdel(handle, inode);

  	ext4_free_blocks(handle, inode, NULL, le32_to_cpu(i_data), 1,

  			 EXT4_FREE_BLOCKS_METADATA |
  			 EXT4_FREE_BLOCKS_FORGET);

  	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);

  	extend_credit_for_blkdel(handle, inode);

  	ext4_free_blocks(handle, inode, NULL, le32_to_cpu(i_data), 1,

  			 EXT4_FREE_BLOCKS_METADATA |
  			 EXT4_FREE_BLOCKS_FORGET);

  	return 0;
  }

  static int free_ind_block(handle_t *handle, struct inode *inode, __le32 *i_data)

  {
  	int retval;

  	/* ei->i_data[EXT4_IND_BLOCK] */
  	if (i_data[0]) {
  		extend_credit_for_blkdel(handle, inode);

  		ext4_free_blocks(handle, inode, NULL,

  				le32_to_cpu(i_data[0]), 1,
  				 EXT4_FREE_BLOCKS_METADATA |
  				 EXT4_FREE_BLOCKS_FORGET);

  	}

  	/* ei->i_data[EXT4_DIND_BLOCK] */
  	if (i_data[1]) {
  		retval = free_dind_blocks(handle, inode, i_data[1]);

  		if (retval)
  			return retval;
  	}

  	/* ei->i_data[EXT4_TIND_BLOCK] */
  	if (i_data[2]) {
  		retval = free_tind_blocks(handle, inode, i_data[2]);

  		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;
  	__le32	i_data[3];

  	struct ext4_inode_info *ei = EXT4_I(inode);
  	struct ext4_inode_info *tmp_ei = EXT4_I(tmp_inode);

  	/*
  	 * One credit accounted for writing the
  	 * i_data field of the original inode
  	 */
  	retval = ext4_journal_extend(handle, 1);

  	if (retval) {

  		retval = ext4_journal_restart(handle, 1);
  		if (retval)
  			goto err_out;
  	}

  	i_data[0] = ei->i_data[EXT4_IND_BLOCK];
  	i_data[1] = ei->i_data[EXT4_DIND_BLOCK];
  	i_data[2] = ei->i_data[EXT4_TIND_BLOCK];
  
  	down_write(&EXT4_I(inode)->i_data_sem);

  	/*

  	 * if EXT4_STATE_EXT_MIGRATE is cleared a block allocation

  	 * happened after we started the migrate. We need to
  	 * fail the migrate
  	 */

  	if (!ext4_test_inode_state(inode, EXT4_STATE_EXT_MIGRATE)) {

  		retval = -EAGAIN;
  		up_write(&EXT4_I(inode)->i_data_sem);
  		goto err_out;
  	} else

  		ext4_clear_inode_state(inode, EXT4_STATE_EXT_MIGRATE);

  	/*

  	 * We have the extent map build with the tmp inode.
  	 * Now copy the i_data across
  	 */

  	ext4_set_inode_flag(inode, EXT4_INODE_EXTENTS);

  	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);

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

  	/*
  	 * We mark the inode dirty after, because we decrement the
  	 * i_blocks when freeing the indirect meta-data blocks
  	 */
  	retval = free_ind_block(handle, inode, i_data);

  	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 = ext4_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);

  	extend_credit_for_blkdel(handle, inode);

  	ext4_free_blocks(handle, inode, NULL, block, 1,

  			 EXT4_FREE_BLOCKS_METADATA | EXT4_FREE_BLOCKS_FORGET);

  	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)

  {
  	handle_t *handle;
  	int retval = 0, i;
  	__le32 *i_data;

  	struct ext4_inode_info *ei;
  	struct inode *tmp_inode = NULL;

  	struct migrate_struct lb;

  	unsigned long max_entries;

  	__u32 goal;

  	uid_t owner[2];

  	/*
  	 * If the filesystem does not support extents, or the inode
  	 * already is extent-based, error out.
  	 */
  	if (!EXT4_HAS_INCOMPAT_FEATURE(inode->i_sb,
  				       EXT4_FEATURE_INCOMPAT_EXTENTS) ||

  	    (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)))

  		return -EINVAL;

  	if (S_ISLNK(inode->i_mode) && inode->i_blocks == 0)
  		/*
  		 * don't migrate fast symlink
  		 */
  		return retval;

  	handle = ext4_journal_start(inode,
  					EXT4_DATA_TRANS_BLOCKS(inode->i_sb) +
  					EXT4_INDEX_EXTRA_TRANS_BLOCKS + 3 +

  					EXT4_MAXQUOTAS_INIT_BLOCKS(inode->i_sb)

  					+ 1);
  	if (IS_ERR(handle)) {
  		retval = PTR_ERR(handle);

  		return retval;

  	}

  	goal = (((inode->i_ino - 1) / EXT4_INODES_PER_GROUP(inode->i_sb)) *
  		EXT4_INODES_PER_GROUP(inode->i_sb)) + 1;

  	owner[0] = inode->i_uid;
  	owner[1] = inode->i_gid;

  	tmp_inode = ext4_new_inode(handle, inode->i_sb->s_root->d_inode,

  				   S_IFREG, NULL, goal, owner);

  	if (IS_ERR(tmp_inode)) {

  		retval = PTR_ERR(inode);

  		ext4_journal_stop(handle);

  		return retval;

  	}
  	i_size_write(tmp_inode, i_size_read(inode));
  	/*

  	 * Set the i_nlink to zero so it will be deleted later
  	 * when we drop inode reference.

  	 */

  	clear_nlink(tmp_inode);

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

  	/*
  	 * start with one credit accounted for
  	 * superblock modification.
  	 *

  	 * For the tmp_inode we already have committed the

  	 * trascation that created the inode. Later as and
  	 * when we add extents we extent the journal
  	 */

  	/*

  	 * Even though we take i_mutex we can still cause block
  	 * allocation via mmap write to holes. If we have allocated
  	 * new blocks we fail migrate.  New block allocation will
  	 * clear EXT4_STATE_EXT_MIGRATE flag.  The flag is updated
  	 * with i_data_sem held to prevent racing with block
  	 * allocation.

  	 */
  	down_read((&EXT4_I(inode)->i_data_sem));

  	ext4_set_inode_state(inode, EXT4_STATE_EXT_MIGRATE);

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

  	handle = ext4_journal_start(inode, 1);

  	if (IS_ERR(handle)) {
  		/*
  		 * It is impossible to update on-disk structures without
  		 * a handle, so just rollback in-core changes and live other
  		 * work to orphan_list_cleanup()
  		 */
  		ext4_orphan_del(NULL, tmp_inode);
  		retval = PTR_ERR(handle);
  		goto out;
  	}

  
  	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;

  	for (i = 0; i < EXT4_NDIR_BLOCKS; i++) {

  		if (i_data[i]) {
  			retval = update_extent_range(handle, tmp_inode,

  						le32_to_cpu(i_data[i]), &lb);

  			if (retval)
  				goto err_out;

  		} else
  			lb.curr_block++;

  	}
  	if (i_data[EXT4_IND_BLOCK]) {
  		retval = update_ind_extent_range(handle, tmp_inode,

  				le32_to_cpu(i_data[EXT4_IND_BLOCK]), &lb);

  			if (retval)
  				goto err_out;
  	} else

  		lb.curr_block += max_entries;

  	if (i_data[EXT4_DIND_BLOCK]) {
  		retval = update_dind_extent_range(handle, tmp_inode,

  				le32_to_cpu(i_data[EXT4_DIND_BLOCK]), &lb);

  			if (retval)
  				goto err_out;
  	} else

  		lb.curr_block += 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]), &lb);

  			if (retval)
  				goto err_out;
  	}
  	/*
  	 * Build the last extent
  	 */
  	retval = finish_range(handle, tmp_inode, &lb);
  err_out:

  	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);
  		if (retval)
  			/*
  			 * if we fail to swap inode data free the extent
  			 * details of the tmp inode
  			 */
  			free_ext_block(handle, tmp_inode);
  	}

  
  	/* We mark the tmp_inode dirty via ext4_ext_tree_init. */
  	if (ext4_journal_extend(handle, 1) != 0)
  		ext4_journal_restart(handle, 1);

  
  	/*
  	 * 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);

  	ext4_journal_stop(handle);

  out:

  	unlock_new_inode(tmp_inode);

  	iput(tmp_inode);

  
  	return retval;
  }