static void ocfs2_calc_trunc_pos(struct inode *inode,
				 struct ocfs2_extent_list *el,
				 struct ocfs2_extent_rec *rec,
				 u32 trunc_start, u32 *trunc_cpos,
				 u32 *trunc_len, u32 *trunc_end,
				 u64 *blkno, int *done)
{
	int ret = 0;
	u32 coff, range;

	range = le32_to_cpu(rec->e_cpos) + ocfs2_rec_clusters(el, rec);

	if (le32_to_cpu(rec->e_cpos) >= trunc_start) {
		/*
		 * remove an entire extent record.
		 */
		*trunc_cpos = le32_to_cpu(rec->e_cpos);
		/*
		 * Skip holes if any.
		 */
		if (range < *trunc_end)
			*trunc_end = range;
		*trunc_len = *trunc_end - le32_to_cpu(rec->e_cpos);
		*blkno = le64_to_cpu(rec->e_blkno);
		*trunc_end = le32_to_cpu(rec->e_cpos);
	} else if (range > trunc_start) {
		/*
		 * remove a partial extent record, which means we're
		 * removing the last extent record.
		 */
		*trunc_cpos = trunc_start;
		/*
		 * skip hole if any.
		 */
		if (range < *trunc_end)
			*trunc_end = range;
		*trunc_len = *trunc_end - trunc_start;
		coff = trunc_start - le32_to_cpu(rec->e_cpos);
		*blkno = le64_to_cpu(rec->e_blkno) +
				ocfs2_clusters_to_blocks(inode->i_sb, coff);
		*trunc_end = trunc_start;
	} else {
		/*
		 * It may have two following possibilities:
		 *
		 * - last record has been removed
		 * - trunc_start was within a hole
		 *
		 * both two cases mean the completion of hole punching.
		 */
		ret = 1;
	}

	*done = ret;
}

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