xfs: eliminate the pos variable in xfs_file_dio_aio_write

	int			unaligned_io = 0;

	int			iolock;

	size_t			count = iov_iter_count(from);

	loff_t			pos = iocb->ki_pos;

	loff_t			end;

	struct iov_iter		data;

	struct xfs_buftarg	*target = XFS_IS_REALTIME_INODE(ip) ?

					mp->m_rtdev_targp : mp->m_ddev_targp;

	/* DIO must be aligned to device logical sector size */

	if (!IS_DAX(inode) && ((pos | count) & target->bt_logical_sectormask))

	if (!IS_DAX(inode) &&

	    ((iocb->ki_pos | count) & target->bt_logical_sectormask))

		return -EINVAL;

	/* "unaligned" here means not aligned to a filesystem block */

	if ((pos & mp->m_blockmask) || ((pos + count) & mp->m_blockmask))

	if ((iocb->ki_pos & mp->m_blockmask) ||

	    ((iocb->ki_pos + count) & mp->m_blockmask))

		unaligned_io = 1;

	/*

	if (ret)

		goto out;

	count = iov_iter_count(from);

	pos = iocb->ki_pos;

	end = pos + count - 1;

	end = iocb->ki_pos + count - 1;

	/*

	 * See xfs_file_read_iter() for why we do a full-file flush here.

	trace_xfs_file_direct_write(ip, count, iocb->ki_pos, 0);

	data = *from;

	ret = mapping->a_ops->direct_IO(iocb, &data, pos);

	ret = mapping->a_ops->direct_IO(iocb, &data, iocb->ki_pos);

	/* see generic_file_direct_write() for why this is necessary */

	if (mapping->nrpages) {

		invalidate_inode_pages2_range(mapping,

					      pos >> PAGE_SHIFT,

					      iocb->ki_pos >> PAGE_SHIFT,

					      end >> PAGE_SHIFT);

	}

	if (ret > 0) {

		pos += ret;

		iocb->ki_pos += ret;

		iov_iter_advance(from, ret);

		iocb->ki_pos = pos;

	}

out:

	xfs_rw_iunlock(ip, iolock);