#! /bin/bash
# SPDX-License-Identifier: GPL-2.0
# Copyright (C) 2017 CTERA Networks. All Rights Reserved.
#
# FS QA Test 036
#
# Test mount error cases with exclusive directories
#
# Overlayfs is often used to mount several mounts that share a single
# lower dir, but every overlayfs mount should have its own private
# upperdir and private workdir.
#
# Overlayfs mount on kernel <= v4.12 does not check if upper/work dirs
# are currently in-use by another overlayfs mount on the system and bad
# things can happen with such configuration.
#
# Commit 2cac0c00a6cd ("ovl: get exclusive ownership on upper/work dirs")
# in kernel v4.13 enforces upper/work dir in-use for any overlayfs mount.
# Later stable fix commit 85fdee1eef1a ("ovl: fix regression caused by
# exclusive upper/work dir protection") relaxes mount failure to a warning
# for index=off mount and fails mount with EBUSY for index=on mount.
#
# This test expects success with index=off and EBUSY with index=on
# when trying to mount overlay with:
# - Upper dir is in-use by another overlay mount
# - Work dir is in-use by another overlay mount
#
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.*
	# unmount the two extra mounts in case they did not fail
	$UMOUNT_PROG $SCRATCH_MNT 2>/dev/null
	$UMOUNT_PROG $SCRATCH_MNT 2>/dev/null
}

# 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
# Use non-default scratch underlying overlay dirs, we need to check
# them explicity after test.
_require_scratch_nocheck
_require_scratch_feature index

# Remove all files from previous tests
_scratch_mkfs

# Create multiple lowerdirs, upperdirs and workdirs
lowerdir=$OVL_BASE_SCRATCH_MNT/lower
lowerdir2=$OVL_BASE_SCRATCH_MNT/lower2
upperdir=$OVL_BASE_SCRATCH_MNT/upper
upperdir2=$OVL_BASE_SCRATCH_MNT/upper2
workdir=$OVL_BASE_SCRATCH_MNT/workdir
workdir2=$OVL_BASE_SCRATCH_MNT/workdir2
mkdir -p $lowerdir $lowerdir2 $upperdir $upperdir2 $workdir $workdir2

# Mount overlay with lowerdir, upperdir, workdir
_overlay_mount_dirs $lowerdir $upperdir $workdir \
		    overlay $SCRATCH_MNT

# Try to mount another overlay with the same upperdir
# with index=off - expect success
_overlay_mount_dirs $lowerdir $upperdir $workdir2 \
		    overlay0 $SCRATCH_MNT -oindex=off && \
		    $UMOUNT_PROG $SCRATCH_MNT

# Try to mount another overlay with the same workdir
# with index=off - expect success
_overlay_mount_dirs $lowerdir2 $upperdir2 $workdir \
		    overlay1 $SCRATCH_MNT -oindex=off && \
		    $UMOUNT_PROG $SCRATCH_MNT

# Try to mount another overlay with the same upperdir
# with index=on - expect EBUSY
_overlay_mount_dirs $lowerdir $upperdir $workdir2 \
	    overlay2 $SCRATCH_MNT -oindex=on 2>&1 | _filter_busy_mount

# Try to mount another overlay with the same workdir
# with index=on - expect EBUSY
_overlay_mount_dirs $lowerdir2 $upperdir2 $workdir \
	    overlay3 $SCRATCH_MNT -oindex=on 2>&1 | _filter_busy_mount

# check overlayfs
_overlay_check_scratch_dirs $lowerdir $upperdir $workdir

# success, all done
status=0
exit