review: xfstests/016 change

[Timothy Shimmin <tes@sgi.com>]

Hi there,

xfstests/016 has been failing for a while in many cases.
It was relying on the log traffic for create/rm to be unaltered
in XFS over the life of XFS.
Its initial purpose was to test out the writing of the log around
wrapping and checking that as we wrapped we didn't corrupt any data
after the end of the log.

The patch is to modify xfstest, 016, to take a sampling of the log traffic
to guestimate how many ops are needed to get to the end of the log,
instead of hard-coding in how many ops are expected to get there.

--Tim


===========================================================================
Index: xfstests/016
===========================================================================

--- a/xfstests/016	2008-05-05 11:26:50.000000000 +1000
+++ b/xfstests/016	2008-05-05 13:07:01.040000000 +1000
@@ -50,7 +50,7 @@ _init()
      echo "*** reset partition"
      $here/src/devzero -b 2048 -n 50 -v 198 $SCRATCH_DEV
      echo "*** mkfs"
-    force_opts="-dsize=50m -lsize=2097152"
+    force_opts="-dsize=50m -lsize=$log_size"
      echo mkfs_xfs $force_opts $SCRATCH_DEV >>$seq.full
      _scratch_mkfs_xfs $force_opts >$tmp.mkfs0 2>&1
      [ $? -ne 0 ] && \
@@ -156,6 +156,10 @@ _supported_os Linux

  rm -f $seq.full

+# mkfs sizes
+log_size=2097152
+log_size_bb=`expr $log_size / 512`
+
  _require_scratch
  _init

@@ -163,27 +167,47 @@ block=`_after_log $SCRATCH_DEV`
  echo "fsblock after log = $block"               >>$seq.full
  _check_corrupt $SCRATCH_DEV $block

-size=`_log_size`
-echo "log size = $size BB"                      >>$seq.full
+actual_log_size=`_log_size`
+echo "log size = $actual_log_size BB"                      >>$seq.full
  head=`_log_head`
  echo "log position = $head"                     >>$seq.full
  lsunit=`_log_sunit`
  echo "log sunit = $lsunit"			>>$seq.full

-[ $size -eq 4096 ] || \
+# sanity checks
+[ $actual_log_size -eq $log_size_bb ] || \
      _fail "!!! unexpected log size $size"
  [ $head -eq 2 -o $head -eq $((lsunit/512)) ] || \
      _fail "!!! unexpected initial log position $head vs. $((lsunit/512))"

-echo "    lots of traffic"                      >>$seq.full
-_log_traffic 850
+# find how how many blocks per op for 100 ops
+# ignore the fact that it will also include an unmount record etc...
+# this should be small overall
+echo "    lots of traffic for sampling" >>$seq.full
+sample_size_ops=100
+_log_traffic $sample_size_ops
+head1=`_log_head`
+num_blocks=`expr $head1 - $head`
+blocks_per_op=`echo "scale=3; $num_blocks / $sample_size_ops" | bc`
+echo "blocks_per_op = $blocks_per_op" >>$seq.full
+num_expected_ops=`echo "$log_size_bb / $blocks_per_op" | bc`
+echo "num_expected_ops = $num_expected_ops" >>$seq.full
+num_expected_to_go=`echo "$num_expected_ops - $sample_size_ops" | bc`
+echo "num_expected_to_go = $num_expected_to_go" >>$seq.full
+
+echo "    lots more traffic" >>$seq.full
+_log_traffic $num_expected_to_go
  head=`_log_head`
  echo "log position = $head"                     >>$seq.full

-[ $head -gt 3850 -a $head -lt 4050 ] || \
-    _fail "!!! unexpected log position $head"
+# e.g. 3891
+near_end_min=`echo "0.95 * $log_size_bb" | bc | sed 's/\..*//'`
+echo "near_end_min = $near_end_min" >>$seq.full
+
+[ $head -gt $near_end_min -a $head -lt $log_size_bb ] || \
+    _fail "!!! unexpected near end log position $head"

-for c in 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
+for c in `seq 0 20`
  do
      echo "   little traffic"            >>$seq.full
      _log_traffic 2
@@ -193,7 +217,7 @@ do
  done

  [ $head -lt 1000 ] || \
-    _fail "!!! unexpected log position $head"
+    _fail "!!! unexpected wrapped log position $head"

  # success, all done
  status=0