generic: add test for truncate/collapse range race

This case tests truncate/collapse range race. If the race occurs, it
will trigger a BUG_ON(). And this kernel patch has fixed this race:
    23fffa9 fs: move falloc collapse range check into the filesystem methods

Signed-off-by: Xiaoguang Wang <wangxg.fnst@cn.fujitsu.com>
Signed-off-by: Xing Gu <gux.fnst@cn.fujitsu.com>
Reviewed-by: Lukas Czerner <lczerner@redhat.com>
Reviewed-by: Eryu Guan <eguan@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

tests/generic/072

@@ -0,0 +1,70 @@
+#! /bin/bash
+# FS QA Test No. 072
+#
+# Test truncate/collapse range race.
+# And this test is also a regression test for kernel commit 23fffa9,
+#    fs: move falloc collapse range check into the filesystem methods
+# If the race occurs, it will trigger a BUG_ON().
+#
+#-----------------------------------------------------------------------
+# Copyright (c) 2015 Fujitsu.  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 $tmp.*
+}
+
+trap "_cleanup; exit \$status" 0 1 2 3 15
+
+# get standard environment, filters and checks
+. ./common/rc
+. ./common/filter
+
+# real QA test starts here
+_supported_os Linux
+_supported_fs generic
+_require_test
+_require_xfs_io_command "fcollapse"
+
+testfile=$TEST_DIR/testfile.$seq
+NCPUS=`$here/src/feature -o`
+OUTER_LOOPS=$((10 * $NCPUS * $LOAD_FACTOR))
+INNER_LOOPS=$((50 * $NCPUS * $LOAD_FACTOR))
+# fcollapse/truncate continuously and simultaneously a same file
+for ((i=1; i <= OUTER_LOOPS; i++)); do
+	for ((i=1; i <= INNER_LOOPS; i++)); do
+		$XFS_IO_PROG -f -c 'truncate 100k' \
+			-c 'fcollapse 0 16k' $testfile > /dev/null 2>&1
+	done &
+	for ((i=1; i <= INNER_LOOPS; i++)); do
+		$XFS_IO_PROG -f -c 'truncate 0' $testfile > /dev/null 2>&1
+	done &
+done
+wait
+
+echo "Silence is golden"
+status=0
+exit

tests/generic/072.out

@@ -0,0 +1,2 @@
+QA output created by 072
+Silence is golden

tests/generic/group

@@ -74,6 +74,7 @@
 069 rw udf auto quick
 070 attr udf auto quick stress
 071 auto quick prealloc
+072 auto metadata stress
 074 rw udf auto
 075 rw udf auto quick
 076 metadata rw udf auto quick stress