[v3,1/2] generic: test data corruption on ext4 caused by written/delayed extent

diff --git a/tests/generic/082 b/tests/generic/082
new file mode 100755
index 0000000..6d3d5df
--- /dev/null
+++ b/tests/generic/082
@@ -0,0 +1,85 @@ 
+#! /bin/bash
+# FS QA Test 082
+#
+# This test exercises the problem with unwritten and delayed extents
+# in ext4 extent status tree where we might in some cases lose a block
+# worth of data. Even though this was a ext4 specific problem the
+# reproducer can be easily run on any file system so let's do that just
+# in case.
+#
+# This test exercises the problem fixed in kernel with commit
+# "ext4: Fix data corruption caused by unwritten and delayed extents"
+#
+#-----------------------------------------------------------------------
+# Copyright (c) 2015 Red Hat, Inc., Lukas Czerner <lczerner@redhat.com>
+#
+# 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 $tmp.*
+}
+
+# get standard environment, filters and checks
+. ./common/rc
+. ./common/filter
+
+# real QA test starts here
+
+# Modify as appropriate.
+_supported_fs generic
+_supported_os IRIX Linux
+_require_test
+_require_xfs_io_command "falloc"
+
+test_file=${TEST_DIR}/testfile-$seq
+
+rm -f $test_file
+
+# The first write creates a delayed extent, fallocate creates
+# unwritten extent which will be marked as delayed in ext4
+# extent status tree. Second write will convert unwritten/delayed
+# block into written/delayed.
+$XFS_IO_PROG -f -c "pwrite -S 0xaa 4096 2048" \
+		-c "falloc 0 131072" \
+		-c "pwrite -S 0xbb 65536 2048" \
+		-c "fsync"  $test_file > $seqres.full 2>&1
+
+# Drop the caches to evict dirty buffers from memory
+echo 3 > /proc/sys/vm/drop_caches
+
+# Write into the second part of the block with 0xbb write from before
+# will create new empty! buffer because the block is still marked as
+# delayed even though it's already written - resulting in
+# overwriting previous data.
+$XFS_IO_PROG -c "pwrite -S 0xdd 67584 2048" $test_file >> $seqres.full 2>&1
+
+# On a faulty ext4 oxbb data will be missing, overwritten by zeroes.
+hexdump -C $test_file
+
+# success, all done
+status=0
+exit
diff --git a/tests/generic/082.out b/tests/generic/082.out
new file mode 100644
index 0000000..ef28b9a
--- /dev/null
+++ b/tests/generic/082.out
@@ -0,0 +1,14 @@ 
+QA output created by 082
+00000000  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
+*
+00001000  aa aa aa aa aa aa aa aa  aa aa aa aa aa aa aa aa  |................|
+*
+00001800  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
+*
+00010000  bb bb bb bb bb bb bb bb  bb bb bb bb bb bb bb bb  |................|
+*
+00010800  dd dd dd dd dd dd dd dd  dd dd dd dd dd dd dd dd  |................|
+*
+00011000  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
+*
+00020000
diff --git a/tests/generic/group b/tests/generic/group
index 63b883c..c6ea3d8 100644
--- a/tests/generic/group
+++ b/tests/generic/group
@@ -84,6 +84,7 @@ 
 079 acl attr ioctl metadata auto quick
 080 auto quick
 081 auto quick
+082 auto prealloc preallocrw quick
 083 rw auto enospc stress
 088 perms auto quick
 089 metadata auto