text: /*
   * 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"
  #include "ext4_extents.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;
  
  	/*
  	 * Worst case we can touch the allocation bitmaps, a bgd
  	 * block, and a block to link in the orphan list.  We do need
  	 * need to worry about credits for modifying the quota inode.
  	 */
  	handle = ext4_journal_start(inode, EXT4_HT_MIGRATE,
  		4 + EXT4_MAXQUOTAS_TRANS_BLOCKS(inode->i_sb));
  
  	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] = i_uid_read(inode);
  	owner[1] = i_gid_read(inode);
  	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(tmp_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, EXT4_HT_MIGRATE, 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;
  }
  
  /*
   * Migrate a simple extent-based inode to use the i_blocks[] array
   */
  int ext4_ind_migrate(struct inode *inode)
  {
  	struct ext4_extent_header	*eh;
  	struct ext4_super_block		*es = EXT4_SB(inode->i_sb)->s_es;
  	struct ext4_inode_info		*ei = EXT4_I(inode);
  	struct ext4_extent		*ex;
  	unsigned int			i, len;
  	ext4_lblk_t			start, end;
  	ext4_fsblk_t			blk;
  	handle_t			*handle;
  	int				ret;
  
  	if (!EXT4_HAS_INCOMPAT_FEATURE(inode->i_sb,
  				       EXT4_FEATURE_INCOMPAT_EXTENTS) ||
  	    (!ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)))
  		return -EINVAL;
  
  	if (EXT4_HAS_RO_COMPAT_FEATURE(inode->i_sb,
  				       EXT4_FEATURE_RO_COMPAT_BIGALLOC))
  		return -EOPNOTSUPP;
  
  	/*
  	 * In order to get correct extent info, force all delayed allocation
  	 * blocks to be allocated, otherwise delayed allocation blocks may not
  	 * be reflected and bypass the checks on extent header.
  	 */
  	if (test_opt(inode->i_sb, DELALLOC))
  		ext4_alloc_da_blocks(inode);
  
  	handle = ext4_journal_start(inode, EXT4_HT_MIGRATE, 1);
  	if (IS_ERR(handle))
  		return PTR_ERR(handle);
  
  	down_write(&EXT4_I(inode)->i_data_sem);
  	ret = ext4_ext_check_inode(inode);
  	if (ret)
  		goto errout;
  
  	eh = ext_inode_hdr(inode);
  	ex  = EXT_FIRST_EXTENT(eh);
  	if (ext4_blocks_count(es) > EXT4_MAX_BLOCK_FILE_PHYS ||
  	    eh->eh_depth != 0 || le16_to_cpu(eh->eh_entries) > 1) {
  		ret = -EOPNOTSUPP;
  		goto errout;
  	}
  	if (eh->eh_entries == 0)
  		blk = len = start = end = 0;
  	else {
  		len = le16_to_cpu(ex->ee_len);
  		blk = ext4_ext_pblock(ex);
  		start = le32_to_cpu(ex->ee_block);
  		end = start + len - 1;
  		if (end >= EXT4_NDIR_BLOCKS) {
  			ret = -EOPNOTSUPP;
  			goto errout;
  		}
  	}
  
  	ext4_clear_inode_flag(inode, EXT4_INODE_EXTENTS);
  	memset(ei->i_data, 0, sizeof(ei->i_data));
  	for (i = start; i <= end; i++)
  		ei->i_data[i] = cpu_to_le32(blk++);
  	ext4_mark_inode_dirty(handle, inode);
  errout:
  	ext4_journal_stop(handle);
  	up_write(&EXT4_I(inode)->i_data_sem);
  	return ret;
  }
  