#! /bin/bash
# SPDX-License-Identifier: GPL-2.0
# Copyright (c) 2017 Oracle.  All Rights Reserved.
#
# FS QA Test 157
#
# The test case is to reproduce a bug in raid6 reconstruction process that
# would end up with read failure if there is data corruption on two disks in
# the same horizontal stripe, e.g.  due to bitrot.
#
# The bug happens when
# a) all disks are good to read,
# b) there is corrupted data on two disks in the same horizontal stripe due to
# something like bitrot,
# c) when rebuilding data after crc fails, btrfs is not able to tell whether
# other copies are good or corrupted because btrfs doesn't have crc for
# unallocated blocks.
#
# The kernel fixes are
# Btrfs: do not merge rbios if their fail stripe index are not identical
# Btrfs: make raid6 rebuild retry more
#
. ./common/preamble
_begin_fstest auto quick raid read_repair

# Import common functions.
. ./common/filter

# real QA test starts here

# Modify as appropriate.
_supported_fs btrfs
_require_scratch_dev_pool 4
_require_btrfs_command inspect-internal dump-tree
_require_btrfs_fs_feature raid56

get_physical()
{
	local stripe=$1
	$BTRFS_UTIL_PROG inspect-internal dump-tree -t 3 $SCRATCH_DEV | \
		grep " DATA\|RAID6" -A 10 | \
		$AWK_PROG "(\$1 ~ /stripe/ && \$3 ~ /devid/ && \$2 ~ /$stripe/) { print \$6 }"
}

get_devid()
{
	local stripe=$1
	$BTRFS_UTIL_PROG inspect-internal dump-tree -t 3 $SCRATCH_DEV | \
		grep " DATA\|RAID6" -A 10 | \
		$AWK_PROG "(\$1 ~ /stripe/ && \$3 ~ /devid/ && \$2 ~ /$stripe/) { print \$4 }"
}

get_device_path()
{
	local devid=$1
	echo "$SCRATCH_DEV_POOL" | $AWK_PROG "{print \$$devid}"
}

_scratch_dev_pool_get 4
# step 1: create a raid6 btrfs and create a 128K file
echo "step 1......mkfs.btrfs" >>$seqres.full

_check_minimal_fs_size $(( 1024 * 1024 * 1024 ))
mkfs_opts="-d raid6 -b 1G"
_scratch_pool_mkfs $mkfs_opts >>$seqres.full 2>&1

# make sure data is written to the start position of the data chunk
_scratch_mount $(_btrfs_no_v1_cache_opt)

# [0,64K) is written to stripe 0 and [64K, 128K) is written to stripe 1
$XFS_IO_PROG -f -d -c "pwrite -S 0xaa 0 128K" -c "fsync" \
	"$SCRATCH_MNT/foobar" | _filter_xfs_io

logical=$(_btrfs_get_first_logical $SCRATCH_MNT/foobar)
_scratch_unmount

phy0=$(get_physical 0)
devid0=$(get_devid 0)
devpath0=$(get_device_path $devid0)
phy1=$(get_physical 1)
devid1=$(get_devid 1)
devpath1=$(get_device_path $devid1)

# step 2: corrupt stripe #0 and #1
echo "step 2......simulate bitrot at:" >>$seqres.full
echo "      ......stripe #0: devid $devid0 devpath $devpath0 phy $phy0" \
	>>$seqres.full
echo "      ......stripe #1: devid $devid1 devpath $devpath1 phy $phy1" \
	>>$seqres.full

$XFS_IO_PROG -f -d -c "pwrite -S 0xbb $phy0 64K" $devpath0 > /dev/null
$XFS_IO_PROG -f -d -c "pwrite -S 0xbb $phy1 64K" $devpath1 > /dev/null

# step 3: read foobar to repair the bitrot
echo "step 3......repair the bitrot" >> $seqres.full
_scratch_mount $(_btrfs_no_v1_cache_opt)

# read the 2nd stripe, i.e. [64K, 128K), to trigger repair
od -x -j 64K $SCRATCH_MNT/foobar

_scratch_dev_pool_put

# success, all done
status=0
exit