generic: test fs freeze/unfreeze and mount/umount race

Exercise fs freeze/unfreeze and mount/umount race, which could lead to
use-after-free oops.

This commit fixed the issue:
1494583 fix get_active_super()/umount() race

This test case is based on a script from Monakhov Dmitriy.

Signed-off-by: Eryu Guan <eguan@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

tests/generic/085

@@ -0,0 +1,106 @@
+#! /bin/bash
+# FS QA Test No. 085
+#
+# Exercise fs freeze/unfreeze and mount/umount race, which could lead to
+# use-after-free oops.
+#
+# This commit fixed the issue:
+# 1494583 fix get_active_super()/umount() race
+#
+#-----------------------------------------------------------------------
+# Copyright (c) 2015 Red Hat Inc. 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.*
+	cleanup_dmdev
+}
+
+# get standard environment, filters and checks
+. ./common/rc
+. ./common/filter
+
+# real QA test starts here
+_supported_fs generic
+_supported_os Linux
+_require_scratch
+_require_block_device $SCRATCH_DEV
+_require_command $DMSETUP_PROG
+_require_freeze
+
+setup_dmdev()
+{
+	table="0 $size_in_sector linear $SCRATCH_DEV 0"
+	$DMSETUP_PROG create $node --table "$table" >>$seqres.full 2>&1 && \
+	$DMSETUP_PROG mknodes >/dev/null 2>&1
+	return $?
+}
+
+cleanup_dmdev()
+{
+	# in case it's still suspended and/or mounted
+	$DMSETUP_PROG resume $lvdev >/dev/null 2>&1
+	$UMOUNT_PROG $lvdev >/dev/null 2>&1
+
+	$DMSETUP_PROG remove $node >>$seqres.full 2>&1
+	$DMSETUP_PROG mknodes >/dev/null 2>&1
+}
+
+rm -f $seqres.full
+echo "Silence is golden"
+
+size=$((256 * 1024 * 1024))
+size_in_sector=$((size / 512))
+_scratch_mkfs_sized $size >>$seqres.full 2>&1
+
+node=$seq-test
+lvdev=/dev/mapper/$node
+setup_dmdev || _fail "setup dm device failed"
+
+# take use of dmsetup suspend to freeze the fs.
+# xfs_freeze/fsfreeze cannot be used in this test, because it can possibly
+# freeze the root fs of the host when SCRATCH_MNT is not mounted
+#
+# And the results of the racing commands (suspend/resume, mount/umount) are not
+# important, as long as they're racing with each other. So just throw away the
+# outputs and ignore the results.
+for ((i=0; i<100; i++)); do
+	$DMSETUP_PROG suspend $lvdev >/dev/null 2>&1
+	$DMSETUP_PROG resume $lvdev >/dev/null 2>&1
+done &
+pid=$!
+for ((i=0; i<100; i++)); do
+	$MOUNT_PROG $lvdev $SCRATCH_MNT >/dev/null 2>&1
+	$UMOUNT_PROG $lvdev >/dev/null 2>&1
+done &
+pid="$pid $!"
+
+wait $pid
+
+status=0
+exit

tests/generic/085.out

@@ -0,0 +1,2 @@
+QA output created by 085
+Silence is golden

tests/generic/group

@@ -87,6 +87,7 @@
 082 auto quick
 083 rw auto enospc stress
 084 auto metadata quick
+085 auto freeze mount
 088 perms auto quick
 089 metadata auto
 091 rw auto quick