overlay: test cases that force read-only mount

Verify that overlay is mounted read-only and that it cannot
be remounted rw.

- Mount with no upper dir
- Failure to create work dir

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Eryu Guan <eguan@redhat.com>
Signed-off-by: Eryu Guan <eguan@redhat.com>

tests/overlay/035

@@ -0,0 +1,87 @@
+#! /bin/bash
+# FS QA Test 035
+#
+# Test cases that force read-only mount
+#
+# - No upper dir
+# - Failure to create work dir
+#
+#-----------------------------------------------------------------------
+# Copyright (C) 2017 CTERA Networks. All Rights Reserved.
+# Author: Amir Goldstein <amir73il@gmail.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 /
+	$CHATTR_PROG -i $workdir
+	rm -f $tmp.*
+}
+
+# get standard environment, filters and checks
+. ./common/rc
+. ./common/filter
+
+# remove previous $seqres.full before test
+rm -f $seqres.full
+
+# real QA test starts here
+_supported_fs overlay
+_supported_os Linux
+_require_scratch
+_require_chattr i
+
+# Remove all files from previous tests
+_scratch_mkfs
+
+# Create multiple lowerdirs and upperdir, workdir
+lowerdir1=$OVL_BASE_SCRATCH_MNT/lower1
+lowerdir2=$OVL_BASE_SCRATCH_MNT/lower2
+upperdir=$OVL_BASE_SCRATCH_MNT/upper
+workdir=$OVL_BASE_SCRATCH_MNT/workdir
+mkdir -p $lowerdir1 $lowerdir2 $upperdir $workdir
+
+# Mount overlay with lower layers only.
+# Verify that overlay is mounted read-only and that it cannot be remounted rw.
+$MOUNT_PROG -t overlay -o"lowerdir=$lowerdir2:$lowerdir1" \
+			$OVL_BASE_SCRATCH_MNT $SCRATCH_MNT
+touch $SCRATCH_MNT/foo 2>&1 | _filter_scratch
+_scratch_remount rw 2>&1 | _filter_scratch
+$UMOUNT_PROG $SCRATCH_MNT
+
+# Make workdir immutable to prevent workdir re-create on mount
+$CHATTR_PROG +i $workdir
+
+# Mount overlay with upper and workdir and expect failure to re-create workdir.
+# Verify that overlay is mounted read-only and that it cannot be remounted rw.
+_overlay_mount_dirs $lowerdir2 $upperdir $workdir \
+		    $OVL_BASE_SCRATCH_MNT $SCRATCH_MNT
+touch $SCRATCH_MNT/bar 2>&1 | _filter_scratch
+_scratch_remount rw 2>&1 | _filter_scratch
+
+# success, all done
+status=0
+exit

tests/overlay/035.out

@@ -0,0 +1,5 @@
+QA output created by 035
+touch: cannot touch 'SCRATCH_MNT/foo': Read-only file system
+mount: cannot remount SCRATCH_DEV read-write, is write-protected
+touch: cannot touch 'SCRATCH_MNT/bar': Read-only file system
+mount: cannot remount SCRATCH_DEV read-write, is write-protected

tests/overlay/group

@@ -37,3 +37,4 @@
 032 auto quick copyup hardlink
 033 auto quick copyup hardlink
 034 auto quick copyup hardlink
+035 auto quick mount