#! /bin/bash
# FS QA Test No. btrfs/037
#
# Test for a btrfs data corruption when using compressed files/extents.
# Under certain cases, it was possible for reads to return random data
# (content from a previously used page) instead of zeroes. This also
# caused partial updates to those regions that were supposed to be filled
# with zeroes to save random (and invalid) data into the file extents.
#
# This is fixed by the commit for the linux kernel titled:
#
#   Btrfs: fix data corruption when reading/updating compressed extents
#
#-----------------------------------------------------------------------
# Copyright (c) 2014 Filipe Manana.  All Rights Reserved.
#
# 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=`mktemp -d`

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

_cleanup()
{
    rm -fr $tmp
}

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

# real QA test starts here
_supported_fs btrfs
_supported_os Linux
_require_scratch

rm -f $seqres.full

_scratch_mkfs >/dev/null 2>&1
_scratch_mount "-o compress-force=lzo"

$XFS_IO_PROG -f -c "pwrite -S 0x06 -b 18670 266978 18670" \
    $SCRATCH_MNT/foobar | _filter_xfs_io
$XFS_IO_PROG -c "falloc 26450 665194" $SCRATCH_MNT/foobar | _filter_xfs_io
$XFS_IO_PROG -c "truncate 542872" $SCRATCH_MNT/foobar | _filter_xfs_io
$XFS_IO_PROG -c "fsync" $SCRATCH_MNT/foobar | _filter_xfs_io

# Expected file items in the fs tree are (from btrfs-debug-tree):
#
#   item 4 key (257 INODE_ITEM 0) itemoff 15879 itemsize 160
#       inode generation 6 transid 6 size 542872 block group 0 mode 100600
#   item 5 key (257 INODE_REF 256) itemoff 15863 itemsize 16
#       inode ref index 2 namelen 6 name: foobar
#   item 6 key (257 EXTENT_DATA 0) itemoff 15810 itemsize 53
#       extent data disk byte 0 nr 0 gen 6
#       extent data offset 0 nr 24576 ram 266240
#       extent compression 0
#   item 7 key (257 EXTENT_DATA 24576) itemoff 15757 itemsize 53
#       prealloc data disk byte 12849152 nr 241664 gen 6
#       prealloc data offset 0 nr 241664
#   item 8 key (257 EXTENT_DATA 266240) itemoff 15704 itemsize 53
#       extent data disk byte 12845056 nr 4096 gen 6
#       extent data offset 0 nr 20480 ram 20480
#       extent compression 2
#   item 9 key (257 EXTENT_DATA 286720) itemoff 15651 itemsize 53
#       prealloc data disk byte 13090816 nr 405504 gen 6
#       prealloc data offset 0 nr 258048
#
# The on disk extent at 266240, contains 5 compressed chunks of file data.
# Each of the first 4 chunks compress 4096 bytes of file data, while the last
# one compresses only 3024 bytes of file data. Because this extent item is not
# the last one in the file, as it followed by a prealloc extent, reads into
# the region [285648 ; 286720[ (length = 4096 - 3024) should return zeroes.

_scratch_unmount
_check_btrfs_filesystem $SCRATCH_DEV

EXPECTED_MD5="b8b0dbb8e02f94123c741c23659a1c0a"

for i in `seq 1 27`
do
    _scratch_mount "-o ro"
    MD5=`md5sum $SCRATCH_MNT/foobar | cut -f 1 -d ' '`
    _scratch_unmount
    if [ "${MD5}x" != "${EXPECTED_MD5}x" ]
    then
	echo "Unexpected file digest (wanted $EXPECTED_MD5, got $MD5)"
    fi
done

status=0
exit
