tests/overlay/073

#! /bin/bash
# SPDX-License-Identifier: GPL-2.0
# Copyright (c) 2020 Chengguang Xu <cgxu519@mykernel.net>.
# All Rights Reserved.
#
# FS QA Test 073
#
# Test whiteout inode sharing functionality.
#
# A "whiteout" is an object that has special meaning in overlayfs.
# A whiteout on an upper layer will effectively hide a matching file
# in the lower layer, making it appear as if the file didn't exist.
#
# Whiteout inode sharing means multiple whiteout objects will share
# one inode in upper layer, without this feature every whiteout object
# will consume one inode in upper layer.

. ./common/preamble
_begin_fstest auto quick whiteout

# Import common functions.
. ./common/filter

# real QA test starts here
_supported_fs overlay
_require_scratch
# Require index dir to test if workdir/work is not in use
# which implies that whiteout sharing is supported
_require_scratch_overlay_features index

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

# Make some testing files in lowerdir.
# Argument:
# $1: Testing file number
make_lower_files()
{
	mkdir $lowerdir/dir
	for name in `seq ${1}`; do
		touch $lowerdir/${name} &>/dev/null
	done
}

# Delete all copied-up files in upperdir.
make_whiteout_files()
{
	# whiteout inode sharing implies that workdir/work is not in use
	# If workdir/work is in use, delete of lower dir will fail and
	# we won't run the test.
	rmdir $workdir/work
	rmdir $SCRATCH_MNT/dir &>/dev/null || \
		_notrun "overlay does not support whiteout inode sharing"
	rm $SCRATCH_MNT/* &>/dev/null
}

# Check link count of whiteout files.
# Arguments:
# $1: Testing file number
# $2: Expected link count
check_whiteout_files()
{
	for name in dir `seq ${1}`; do
		local real_count=`stat -c %h $upperdir/${name} 2>/dev/null`
		if [[ ${2} != $real_count ]]; then
			echo "Expected link count is ${2} but real count is $real_count, file name is ${name}"
		fi
	done
	local tmpfile_count=`ls $workdir/index/\#* 2>/dev/null |wc -l 2>/dev/null`
	if [[ -n "$tmpfile_count" && $tmpfile_count > 1 ]]; then
		echo "There are more than one whiteout tmpfile in index dir!"
		ls -l $workdir/index/\#* 2>/dev/null
	fi
}

# Run test case with specific arguments.
# Arguments:
# $1: Testing file number
# $2: Expected link count
run_test_case()
{
	_scratch_mkfs
	make_lower_files ${1}
	# There will be extra hard links with nfs_export enabled which
	# is expected. Turn it off explicitly to avoid the false alarm.
	_scratch_mount -o "index=on,nfs_export=off"
	make_whiteout_files
	check_whiteout_files ${1} ${2}
	_scratch_unmount
}

# Test case
file_count=10
# +1 for dir +1 for temp whiteout
link_count=12
run_test_case $file_count $link_count

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