int nilfs_ifile_read(struct super_block *sb, struct nilfs_root *root,
		     size_t inode_size, struct nilfs_inode *raw_inode,
		     struct inode **inodep)
{
	struct inode *ifile;
	int err;

	ifile = nilfs_iget_locked(sb, root, NILFS_IFILE_INO);
	if (unlikely(!ifile))
		return -ENOMEM;
	if (!(ifile->i_state & I_NEW))
		goto out;

	err = nilfs_mdt_init(ifile, NILFS_MDT_GFP,
			     sizeof(struct nilfs_ifile_info));
	if (err)
		goto failed;

	err = nilfs_palloc_init_blockgroup(ifile, inode_size);
	if (err)
		goto failed;

	nilfs_palloc_setup_cache(ifile, &NILFS_IFILE_I(ifile)->palloc_cache);

	err = nilfs_read_inode_common(ifile, raw_inode);
	if (err)
		goto failed;

	unlock_new_inode(ifile);
 out:
	*inodep = ifile;
	return 0;
 failed:
	iget_failed(ifile);
	return err;
}
/**
 * nilfs_sufile_read - read or get sufile inode
 * @sb: super block instance
 * @susize: size of a segment usage entry
 * @raw_inode: on-disk sufile inode
 * @inodep: buffer to store the inode
 */
int nilfs_sufile_read(struct super_block *sb, size_t susize,
		      struct nilfs_inode *raw_inode, struct inode **inodep)
{
	struct inode *sufile;
	struct nilfs_sufile_info *sui;
	struct buffer_head *header_bh;
	struct nilfs_sufile_header *header;
	void *kaddr;
	int err;

	if (susize > sb->s_blocksize) {
		printk(KERN_ERR
		       "NILFS: too large segment usage size: %zu bytes.\n",
		       susize);
		return -EINVAL;
	} else if (susize < NILFS_MIN_SEGMENT_USAGE_SIZE) {
		printk(KERN_ERR
		       "NILFS: too small segment usage size: %zu bytes.\n",
		       susize);
		return -EINVAL;
	}

	sufile = nilfs_iget_locked(sb, NULL, NILFS_SUFILE_INO);
	if (unlikely(!sufile))
		return -ENOMEM;
	if (!(sufile->i_state & I_NEW))
		goto out;

	err = nilfs_mdt_init(sufile, NILFS_MDT_GFP, sizeof(*sui));
	if (err)
		goto failed;

	nilfs_mdt_set_entry_size(sufile, susize,
				 sizeof(struct nilfs_sufile_header));

	err = nilfs_read_inode_common(sufile, raw_inode);
	if (err)
		goto failed;

	err = nilfs_sufile_get_header_block(sufile, &header_bh);
	if (err)
		goto failed;

	sui = NILFS_SUI(sufile);
	kaddr = kmap_atomic(header_bh->b_page, KM_USER0);
	header = kaddr + bh_offset(header_bh);
	sui->ncleansegs = le64_to_cpu(header->sh_ncleansegs);
	kunmap_atomic(kaddr, KM_USER0);
	brelse(header_bh);

	sui->allocmax = nilfs_sufile_get_nsegments(sufile) - 1;
	sui->allocmin = 0;

	unlock_new_inode(sufile);
 out:
	*inodep = sufile;
	return 0;
 failed:
	iget_failed(sufile);
	return err;
}