ext4: test for DAX + journaling corruption

Add a regression test for the following kernel commit:

  ext4: prevent data corruption with journaling + DAX

The test passes if either we successfully compare the data between
the mmap with journaling turned on and the one with journaling
turned off, or if we fail the chattr command to turn on or off
journaling.  The latter is how we prevent this issue in the kernel.

[eguan: add 'dax' group]

Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Reviewed-by: Eryu Guan <eguan@redhat.com>
Signed-off-by: Eryu Guan <eguan@redhat.com>

tests/ext4/030

@@ -0,0 +1,74 @@
+#! /bin/bash
+# FS QA Test ext4/030
+#
+# This is a regression test for kernel patch:
+#   ext4: prevent data corruption with journaling + DAX
+# created by Ross Zwisler <ross.zwisler@linux.intel.com>
+#
+#-----------------------------------------------------------------------
+# Copyright (c) 2017-2018 Intel Corporation.  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!
+trap "_cleanup; exit \$status" 0 1 2 3 15
+
+_cleanup()
+{
+	cd /
+	rm -f $tmp.*
+}
+
+# get standard environment, filters and checks
+. ./common/rc
+. ./common/filter
+
+# remove previous $seqres.full before test
+rm -f $seqres.full
+
+# Modify as appropriate.
+_supported_os Linux
+_supported_fs ext4
+_require_scratch_dax
+_require_test_program "t_ext4_dax_journal_corruption"
+_require_command "$CHATTR_PROG" chattr
+
+# real QA test starts here
+_scratch_mkfs > $seqres.full 2>&1
+
+# In order to get our failure condition consistently we need to turn off
+# delayed allocation.  With delayed allocation on this simple test will pass,
+# but we would almost certainly see data corruption down the road as the
+# contents of the journal would conflict with the DAX data.
+_scratch_mount "-o dax,nodelalloc" >> $seqres.full 2>&1
+
+$here/src/t_ext4_dax_journal_corruption $CHATTR_PROG $SCRATCH_MNT/testfile
+
+if [[ $? != 0 && $? != 77 ]]; then
+	echo "Test failed, status $?"
+	exit 1
+fi
+
+# success, all done
+echo "Silence is golden"
+status=0
+exit

tests/ext4/030.out

@@ -0,0 +1,2 @@
+QA output created by 030
+Silence is golden

tests/ext4/group

@@ -32,6 +32,7 @@
 027 auto quick fsmap
 028 auto quick fsmap
 029 auto quick fsmap
+030 auto quick dax
 271 auto rw quick
 301 aio auto ioctl rw stress defrag
 302 aio auto ioctl rw stress defrag