static int ocfs2_zero_extend_range(struct inode *inode, u64 range_start,
				   u64 range_end, struct buffer_head *di_bh)
{
	int rc = 0;
	u64 next_pos;
	u64 zero_pos = range_start;

	trace_ocfs2_zero_extend_range(
			(unsigned long long)OCFS2_I(inode)->ip_blkno,
			(unsigned long long)range_start,
			(unsigned long long)range_end);
	BUG_ON(range_start >= range_end);

	while (zero_pos < range_end) {
		next_pos = (zero_pos & PAGE_MASK) + PAGE_SIZE;
		if (next_pos > range_end)
			next_pos = range_end;
		rc = ocfs2_write_zero_page(inode, zero_pos, next_pos, di_bh);
		if (rc < 0) {
			mlog_errno(rc);
			break;
		}
		zero_pos = next_pos;

		/*
		 * Very large extends have the potential to lock up
		 * the cpu for extended periods of time.
		 */
		cond_resched();
	}

	return rc;
}
static int ocfs2_zero_extend_range(struct inode *inode, u64 range_start,
				   u64 range_end, struct buffer_head *di_bh)
{
	int rc = 0;
	u64 next_pos;
	u64 zero_pos = range_start;

	trace_ocfs2_zero_extend_range(
			(unsigned long long)OCFS2_I(inode)->ip_blkno,
			(unsigned long long)range_start,
			(unsigned long long)range_end);
	BUG_ON(range_start >= range_end);

	while (zero_pos < range_end) {
		next_pos = (zero_pos & PAGE_MASK) + PAGE_SIZE;
		if (next_pos > range_end)
			next_pos = range_end;
		rc = ocfs2_write_zero_page(inode, zero_pos, next_pos, di_bh);
		if (rc < 0) {
			mlog_errno(rc);
			break;
		}
		zero_pos = next_pos;

		 
		cond_resched();
	}

	return rc;
}