#! /bin/bash
# SPDX-License-Identifier: GPL-2.0
# Copyright (C) 2018 CTERA Networks. All Rights Reserved.
#
# FS QA Test 049
#
# Test multiple redirects to the same lower dir.
#
# Multiple redirects to the same lower dir will falsely return the same
# st_ino/st_dev for two different upper dirs and will cause 'diff' to
# falsely report that content of directories is the same when it is not.
#
# This test checks that overlayfs detects and fails lookup of a multiply
# redirected dir.
#
# The check for multiply redirected dir 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 dir to create a redirected upper dir and
# touch lower file to create copy up with origin xattr
create_redirect()
{
	local redirect=$1

	mkdir -p $lowerdir/origin
	touch $lowerdir/origin/file

	_scratch_mount -o redirect_dir=on
	touch $SCRATCH_MNT/origin/file
	mv $SCRATCH_MNT/origin $SCRATCH_MNT/$redirect

	$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
_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 redirected dir with copied up file
create_redirect redirect1
# Duplicate the redirected dir and copied up file
cp -a $upperdir/redirect1 $upperdir/redirect2

# Diverge the content of the two copies of file
# and the content of two copies of redirected dir
echo right >> $upperdir/redirect1/file
touch $upperdir/redirect1/right
echo wrong >> $upperdir/redirect2/file
touch $upperdir/redirect2/wrong

_scratch_mount -o redirect_dir=on

# If both copies of file/dir use the same st_dev/st_ino in overlay
# diff won't detect that their content differs
diff -q $SCRATCH_MNT/redirect1/file $SCRATCH_MNT/redirect2/file &>/dev/null && \
	echo "diff on files inside duplicate redirect parent doesn't know right from wrong!"

diff -q $SCRATCH_MNT/redirect1 $SCRATCH_MNT/redirect2 &> /dev/null && \
	echo "diff on duplicate redirect dirs doesn't know right from wrong!"

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