tests/overlay/044

#! /bin/bash
# FSQA Test No. 044
#
# Test hardlink breakage on non-samefs setup
# This is a variant of overlay/018 to test.
#
# This simple test demonstrates a known issue with overlayfs:
# - file A and B are hardlinked in lower
# - modify A to trigger copy up
# - file A is no longer a hardlink of file B
#
#-----------------------------------------------------------------------
#
# Copyright (C) 2017 IBM Corporation. All Rights Reserved.
# Author: Chandan Rajendra <chandan@linux.vnet.ibm.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"

tmp=/tmp/$$
status=1	# failure is the default!
trap "_cleanup; exit \$status" 0 1 2 3 15

_cleanup()
{
	rm -f $tmp.*
}

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

# real QA test starts here
_supported_fs overlay
_supported_os Linux
# Use non-default scratch underlying overlay dirs, we need to check
# them explicity after test.
_require_scratch_nocheck
_require_test
_require_scratch_feature index
_require_test_program "t_dir_type"

rm -f $seqres.full

# Record inode numbers in format <ino> <nlink>
function record_ino_nlink()
{
	ls -li $FILES | awk '{ print $1, $3, $10}' > $1
}

# Check inode numbers match recorded inode numbers
function check_ino_nlink()
{
	dir=$1
	before=$2
	after=$3

	record_ino_nlink $after

	# Test constant stat(2) st_ino/st_nlink -
	#   Compare before..after - expect silence
	# We use diff -u so out.bad will tell us which stage failed
	diff -u $before $after

	# Test constant readdir(3)/getdents(2) d_ino -
	#   Expect to find file by inode number
	cat $before | while read ino nlink f; do
		$here/src/t_dir_type $dir $ino | grep -q $(basename $f) || \
			echo "$(basename $f) not found by ino $ino (from $before)"
	done
}

lowerdir=$OVL_BASE_TEST_DIR/$seq-ovl-lower
rm -rf $lowerdir
mkdir $lowerdir

# Create 2 hardlinked files in lower
echo "zero" >> $lowerdir/foo
ln $lowerdir/foo $lowerdir/bar

_scratch_mkfs >>$seqres.full 2>&1

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

# Enable overlay index feature to prevent breaking hardlinks on copy up.
# Enabling xino in this test requires that base filesystem inode numbers will
# not use bit 63 in inode number of the test files, because bit 63 is used by
# overlayfs to indicate the layer. Let's just assume that this is true for all
# tested filesystems and if we are wrong, the test may fail.
_overlay_scratch_mount_dirs $lowerdir $upperdir $workdir -o index=on,xino=on || \
	_notrun "cannot mount overlay with xino=on option"
_fs_options $SCRATCH_DEV | grep -q "xino=on" || \
	_notrun "cannot enable xino feature"

rm -f $tmp.*

foo=$SCRATCH_MNT/foo
bar=$SCRATCH_MNT/bar

FILES="$foo $bar"

echo "== Before copy up =="
cat $FILES
record_ino_nlink $tmp.before

# Modify content of one of the hardlinks
# Intentionally modify the last hardlink in $FILES, so after mount cycle
# when reading the first file in $FILES, last file won't be in inode/dcache
echo "one" >> $bar

echo "== After write one =="
cat $FILES
check_ino_nlink $SCRATCH_MNT $tmp.before $tmp.after_one

# Verify that the hardlinks survive a mount cycle
$UMOUNT_PROG $SCRATCH_MNT
_overlay_check_scratch_dirs $lowerdir $upperdir $workdir -o index=on,xino=on
_overlay_scratch_mount_dirs $lowerdir $upperdir $workdir -o index=on,xino=on

echo "== After mount cycle =="
cat $FILES
check_ino_nlink $SCRATCH_MNT $tmp.after_one $tmp.after_cycle

# Drop caches to get the copied up hardlink out of cache
echo 3 > /proc/sys/vm/drop_caches

# Modify content of the other hardlink
echo "two" >> $foo

echo "== After write two =="
cat $FILES
check_ino_nlink $SCRATCH_MNT $tmp.after_one $tmp.after_two

# check overlayfs
_overlay_check_scratch_dirs $lowerdir $upperdir $workdir -o index=on

status=0
exit