tests/btrfs/086

#! /bin/bash
# FS QA Test No. btrfs/086
#
# Test cloning a file range with a length of zero into a destination offset
# greater than zero.
#
# This made btrfs create an extent state record with a start offset greater than
# the end offset, resulting in chaos such as an infinite loop when evicting an
# inode.
#
# This issue was fixed by the following linux kernel patch:
#
#   Btrfs: fix inode eviction infinite loop after cloning into it
#
#-----------------------------------------------------------------------
# Copyright (C) 2015 SUSE Linux Products GmbH. All Rights Reserved.
# Author: Filipe Manana <fdmanana@suse.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 btrfs
_supported_os Linux
_require_scratch
_require_cloner

rm -f $seqres.full

_scratch_mkfs >>$seqres.full 2>&1
_scratch_mount

touch $SCRATCH_MNT/foo
touch $SCRATCH_MNT/bar

# Now attempt to clone foo into bar. Because we pass a length of zero, the
# clone ioctl will adjust the length to match the size of the file foo (minus
# the source offset which is zero) - because the adjusted length value is
# zero, it made btrfs create an extent state record for file bar with a start
# offset (64k) greater then its end offset (64k - 1), which is something never
# supposed to happen and for example it made inode eviction enter an infinite
# loop that dumped a warning trace on each iteration.
$CLONER_PROG -s 0 -d 65536 -l 0 $SCRATCH_MNT/foo $SCRATCH_MNT/bar
echo "bar file size after clone operation: $(stat -c %s $SCRATCH_MNT/bar)"

status=0
exit