Readdir w/offset validation.

Verify using xfs_io that readdir offsets match expected output.

Signed-off-by: Auke Kok <auke.kok@versity.com>

tests/tests/simple-readdir.sh

@@ -0,0 +1,37 @@
+#
+# verify d_off output of xfs_io is consistent.
+#
+
+t_require_commands xfs_io
+
+filt()
+{
+	grep d_off | cut -d ' ' -f 1,4-
+}
+
+echo "== create content"
+for s in $(seq 1 7 250); do
+	f=$(printf '%*s' $s | tr ' ' 'a')
+	touch ${T_D0}/$f
+done
+
+echo "== readdir all"
+xfs_io -c "readdir -v" $T_D0 | filt
+
+echo "== readdir offset"
+xfs_io -c "readdir -v -o 20" $T_D0 | filt
+
+echo "== readdir len (bytes)"
+xfs_io -c "readdir -v -l 193" $T_D0 | filt
+
+echo "== introduce gap"
+for s in $(seq 57 7 120); do
+	f=$(printf '%*s' $s | tr ' ' 'a')
+	rm -f ${T_D0}/$f
+done
+xfs_io -c "readdir -v" $T_D0 | filt
+
+echo "== cleanup"
+rm -rf $T_D0
+
+t_pass