#! /bin/bash
# SPDX-License-Identifier: GPL-2.0
# Copyright (c) 2017 Oracle.  All Rights Reserved.
#
# FS QA Test btrfs/150
#
# This is a regression test which ends up with a kernel oops in btrfs.
# It occurs when btrfs's read repair happens while reading a compressed
# extent.
# The patch to fix it is
#	Btrfs: fix kernel oops while reading compressed data
#
seq=`basename $0`
seqres=$RESULT_DIR/$seq
echo "QA output created by $seq"

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

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

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

# remove previous $seqres.full before test
rm -f $seqres.full

# real QA test starts here

# Modify as appropriate.
_supported_fs btrfs
_supported_os Linux
_require_scratch
_require_fail_make_request
_require_scratch_dev_pool 2
_scratch_dev_pool_get 2

SYSFS_BDEV=`_sysfs_dev $SCRATCH_DEV`
enable_io_failure()
{
	echo 100 > $DEBUGFS_MNT/fail_make_request/probability
	echo 1000 > $DEBUGFS_MNT/fail_make_request/times
	echo 0 > $DEBUGFS_MNT/fail_make_request/verbose
	echo 1 > $DEBUGFS_MNT/fail_make_request/task-filter
	echo 1 > $SYSFS_BDEV/make-it-fail
}

disable_io_failure()
{
	echo 0 > $DEBUGFS_MNT/fail_make_request/probability
	echo 0 > $DEBUGFS_MNT/fail_make_request/times
	echo 0 > $DEBUGFS_MNT/fail_make_request/task-filter
	echo 0 > $SYSFS_BDEV/make-it-fail
}

_scratch_pool_mkfs "-d raid1 -b 1G" >> $seqres.full 2>&1

# It doesn't matter which compression algorithm we use.
_scratch_mount -ocompress

# Create a file with all data being compressed
$XFS_IO_PROG -f -c "pwrite -W 0 8K" $SCRATCH_MNT/foobar | _filter_xfs_io

# Raid1 consists of two copies and btrfs decides which copy to read by reader's
# %pid.  Now we inject errors to copy #1 and copy #0 is good.  We want to read
# the bad copy to trigger read-repair.
while [[ -z $result ]]; do
	# invalidate the page cache
	$XFS_IO_PROG -f -c "fadvise -d 0 8K" $SCRATCH_MNT/foobar

	enable_io_failure

	result=$(bash -c "
	if [ \$((\$\$ % 2)) == 1 ]; then
		echo 1 > /proc/\$\$/make-it-fail
		exec $XFS_IO_PROG -c \"pread 0 8K\" \$SCRATCH_MNT/foobar
	fi")

	disable_io_failure
done

_scratch_dev_pool_put
# success, all done
status=0
exit