#! /bin/bash
# SPDX-License-Identifier: GPL-2.0
# Copyright (C) 2018 CTERA Networks. All Rights Reserved.
#
# FS QA Test 059
#
# Test multiple origin references to the same lower file.
#
# Multiple origin references to the same lower file from upper files that
# are not hardlinks will falsely return the same st_ino/st_dev for two
# different overlay files and will cause 'diff' to falsely report that
# content of files is the same when it is not.
#
# This test checks that overlayfs detects and fails lookup of a multiply
# referenced origin.
#
# The check for multiply referenced origin was a by-product of kernel
# commit 31747eda41ef ("ovl: hash directory inodes for fsnotify")
#
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.*
}

# Rename lower file to create copy up with origin xattr
create_origin_ref()
{
	local ref=$1

	touch $lowerdir/origin

	# Enabling redirect_dir may seem irrelevant to rename of non-dir,
	# but with upcoming 'metacopy' feature, redirects will be set also
	# on non-dir and may also create multiple redirects.
	_scratch_mount -o redirect_dir=on
	mv $SCRATCH_MNT/origin $SCRATCH_MNT/$ref

	$UMOUNT_PROG $SCRATCH_MNT
}

# get standard environment, filters and checks
. ./common/rc
. ./common/filter

rm -f $seqres.full

# real QA test starts here
_supported_fs overlay
_supported_os Linux
_require_scratch_nocheck
_require_scratch_feature redirect_dir

# remove all files from previous runs
_scratch_mkfs

upperdir=$OVL_BASE_SCRATCH_MNT/$OVL_UPPER
lowerdir=$OVL_BASE_SCRATCH_MNT/$OVL_LOWER

# Create copied up file with origin xattr
create_origin_ref ref1
# Duplicate the copied up file
cp -a $upperdir/ref1 $upperdir/ref2

# Diverge the content of the two copies of file
# and the content of two copies of redirected dir
echo right >> $upperdir/ref1
echo wrong >> $upperdir/ref2

_scratch_mount -o redirect_dir=on

# If both copies of file use the same st_dev/st_ino in overlay
# diff won't detect that their content differs
diff -q $SCRATCH_MNT/ref1 $SCRATCH_MNT/ref2 &>/dev/null && \
	echo "diff on duplicated upper files doesn't know right from wrong!"

# success, all done
echo "Silence is golden"
status=0
exit