btrfs: test snapshot create with invalid parent qgroup

Test that an invalid parent qgroup does not cause snapshot create to
force the FS readonly.

In btrfs, create_pending_snapshot() will go readonly on _any_ error return
from
btrfs_qgroup_inherit(). If qgroups are enabled, a user can crash their fs by
just making a snapshot and asking it to inherit from an invalid qgroup.

This patch does exactly that test. If the FS goes readonly that will be
reported and we will know that a regression was introduced.

The btrfs fix this patch relates to can be found at the following url:
http://thread.gmane.org/gmane.comp.file-systems.btrfs/54755

Thanks,
	--Mark

Signed-off-by: Mark Fasheh <mfasheh@suse.de>
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

tests/btrfs/121

@@ -0,0 +1,68 @@
+#! /bin/bash
+# FS QA Test No. btrfs/121
+#
+# Test that an invalid parent qgroup does not cause snapshot create to
+# force the FS readonly.
+#
+# This issue is fixed by the following btrfs patch:
+#  [PATCH] btrfs: handle non-fatal errors in btrfs_qgroup_inherit()
+#  http://thread.gmane.org/gmane.comp.file-systems.btrfs/54755
+#
+#-----------------------------------------------------------------------
+# Copyright (C) 2016 SUSE Linux Products GmbH. 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
+
+# real QA test starts here
+_supported_fs btrfs
+_supported_os Linux
+_require_scratch
+
+rm -f $seqres.full
+
+_scratch_mkfs
+_scratch_mount
+_run_btrfs_util_prog quota enable $SCRATCH_MNT
+# The qgroup '1/10' does not exist and should be silently ignored
+_run_btrfs_util_prog subvolume snapshot -i 1/10 $SCRATCH_MNT $SCRATCH_MNT/snap1
+
+echo "Silence is golden"
+
+status=0
+exit

tests/btrfs/121.out

@@ -0,0 +1,2 @@
+QA output created by 121
+Silence is golden

tests/btrfs/group

@@ -121,3 +121,4 @@
 118 auto quick snapshot metadata
 119 auto quick snapshot metadata qgroup
 120 auto quick snapshot metadata
+121 auto quick snapshot qgroup