xfstests: btrfs/013 regression test for prealloc with balance

We had a regression where we were not copying csums properly when balancing a
prealloc extent.  Unfortunately the way this showed up the most was with the
csum simply missing, which doesn't result in an error to userspace.  So I've
copied what generic/310 does and check dmesg for csum errors when the test
starts and then compare that count to the csum errors after the test finishes to
see if there was a problem.  This approach caught the error without my fix, and
then passed fine with my fix in place but with the previous errors still in
dmesg.  Thanks,

[rjohnston: changed test number to 13]

Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Reviewed-by: Stefan Behrens <sbehrens@giantdisaster.de>
Signed-off-by: Rich Johnston <rjohnston@sgi.com>

tests/btrfs/013

@@ -0,0 +1,87 @@
+#! /bin/bash
+# FS QA Test No. btrfs/013
+#
+# Regression test for balance with prealloc extents.  This checks to make sure
+# we are balacing prealloc'ed extents properly by making sure we don't have any
+# csum errors.  Unfortunately this manifests itself with no csum which means
+# userspace doesn't get an error when reading the file back so we have to grok
+# dmesg to see if there was a csum error.
+#
+#-----------------------------------------------------------------------
+# Copyright (c) 2013 Fusion IO.  All Rights Reserved.
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License as
+# published by the Free Software Foundation.
+#
+# This program is distributed in the hope that it would be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write the Free Software Foundation,
+# Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+#
+#-----------------------------------------------------------------------
+#
+
+seq=`basename $0`
+seqres=$RESULT_DIR/$seq
+echo "QA output created by $seq"
+
+here=`pwd`
+tmp=/tmp/$$
+
+status=1	# failure is the default!
+
+_cleanup()
+{
+	rm -f $tmp.*
+}
+
+trap "_cleanup ; exit \$status" 0 1 2 3 15
+
+# get standard environment, filters and checks
+. ./common/rc
+. ./common/filter
+
+# real QA test starts here
+_supported_fs btrfs
+_supported_os Linux
+_require_scratch
+
+rm -f $seqres.full
+
+_scratch_mkfs > /dev/null 2>&1
+_scratch_mount
+
+nr_csum_no_found=$(dmesg | grep -c "no csum found")
+nr_csum_failed=$(dmesg | grep -c "csum failed")
+
+_check_csum_error()
+{
+	new_csum_no_found=$(dmesg | grep -c "no csum found")
+	new_csum_failed=$(dmesg | grep -c "csum failed")
+
+	if [ $nr_csum_no_found -eq $new_csum_no_found -a \
+	     $nr_csum_failed -eq $new_csum_failed ]; then
+		return 0
+	fi
+	return 1
+}
+$XFS_IO_PROG -f -c "falloc 0 1M" -c "pwrite 16k 8k" -c "fsync" \
+	$SCRATCH_MNT/foo > $seqres.full 2>&1
+$BTRFS_UTIL_PROG fi ba $SCRATCH_MNT >> $seqres.full 2>&1 || \
+	_fail "balance failed"
+_scratch_unmount
+_scratch_mount
+$XFS_IO_PROG -c "pread 0 1M" $SCRATCH_MNT/foo >> $seqres.full 2>&1 || \
+	_fail "pread failed"
+
+# This sucks but unfortunately it is the only way to be sure something didn't go
+# wrong.
+_check_csum_error || _fail "csum detected, please check dmesg"
+
+echo "Silence is golden"
+status=0 ; exit

tests/btrfs/013.out

@@ -0,0 +1,2 @@
+QA output created by 013
+Silence is golden

tests/btrfs/group

@@ -15,3 +15,4 @@
 010 auto quick
 011 auto
 012 auto
+013 auto quick