#! /bin/bash
# SPDX-License-Identifier: GPL-2.0
# Copyright (C) 2020 SUSE Linux Products GmbH. All Rights Reserved.
#
# FS QA Test 213
#
# Test if canceling a running balance can lead to dead looping balance
#
. ./common/preamble
_begin_fstest auto balance

# Override the default cleanup function.
_cleanup()
{
	cd /
	kill $write_pid &> /dev/null
	rm -f $tmp.*
}

. ./common/filter

_supported_fs btrfs
_require_scratch
_require_xfs_io_command pwrite -D

_fixed_by_kernel_commit 1dae7e0e58b4 \
	"btrfs: reloc: clear DEAD_RELOC_TREE bit for orphan roots to prevent runaway balance"

_scratch_mkfs >> $seqres.full
_scratch_mount

max_space=$(_get_total_space $SCRATCH_MNT)
max_space=$(( max_space / 2 ))

# Create enough IO so that we need around 8 seconds to relocate it.
start_ts=$(_wallclock)
$TIMEOUT_PROG 8s $XFS_IO_PROG -f -c "pwrite -D -b 1M 0 $max_space" \
	"$SCRATCH_MNT/file" > /dev/null 2>&1
stop_ts=$(_wallclock)

runtime=$(( stop_ts - start_ts ))

# Unmount and mount again the fs to clear any cached data and metadata, so that
# it's less likely balance has already finished when we try to cancel it below.
_scratch_cycle_mount

# Now balance should take at least $runtime seconds, we can cancel it at
# $runtime/4 to ensure a success cancel.
_run_btrfs_balance_start -d --bg "$SCRATCH_MNT"
sleep $(($runtime / 4))
# It's possible that balance has already completed. It's unlikely but often
# it may happen due to virtualization, caching and other factors, so ignore
# any error about no balance currently running.
$BTRFS_UTIL_PROG balance cancel "$SCRATCH_MNT" 2>&1 | grep -iq 'not in progress'
if [ $? -eq 0 ]; then
	_notrun "balance finished before we could cancel it"
fi

# Now check if we can finish relocating metadata, which should finish very
# quickly.
$BTRFS_UTIL_PROG balance start -m "$SCRATCH_MNT" >> $seqres.full

echo "Silence is golden"

# success, all done
status=0
exit