xfs: use xfs_inode_buftarg in xfs_file_ioctl

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>

fs/xfs/xfs_ioctl.c

@@ -2135,10 +2135,8 @@ xfs_file_ioctl(
 		return xfs_ioc_space(filp, cmd, &bf);
 	}
 	case XFS_IOC_DIOINFO: {
-		struct dioattr	da;
-		xfs_buftarg_t	*target =
-			XFS_IS_REALTIME_INODE(ip) ?
-			mp->m_rtdev_targp : mp->m_ddev_targp;
+		struct xfs_buftarg	*target = xfs_inode_buftarg(ip);
+		struct dioattr		da;
 
 		da.d_mem =  da.d_miniosz = target->bt_logical_sectorsize;
 		da.d_maxiosz = INT_MAX & ~(da.d_miniosz - 1);