generic/224: filter out expected XFS warnings for mixed direct/buffer I/O

generic/224 is doing concurrent direct and buffered I/O to the same
set of files, and this triggers some expected warnings on XFS. So
filter out these warnings just like what we did in generic/095 and
generic/247.

Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Eryu Guan <eguan@redhat.com>

tests/generic/224

@@ -82,5 +82,14 @@ for i in `seq 0 1 $FILES`; do
 done
 wait
 echo "*** Silence is golden ***"
-status=0
+
+# unmount and check dmesg, filtering out expected XFS warnings about mixed
+# direct and buffered I/O
+_scratch_unmount
+if [ "$FSTYP" == "xfs" ]; then
+	_check_dmesg _filter_xfs_dmesg
+else
+	_check_dmesg
+fi
+status=$?
 exit