#! /bin/bash
# SPDX-License-Identifier: GPL-2.0
# Copyright (C) 2023 SUSE Linux Products GmbH. All Rights Reserved.
#
# FS QA Test 282
#
# Make sure scrub speed limitation works as expected.
#
. ./common/preamble
_begin_fstest auto scrub

. ./common/filter

_supported_fs btrfs
_wants_kernel_commit eb3b50536642 \
	"btrfs: scrub: per-device bandwidth control"

# We want at least 5G for the scratch device.
_require_scratch_size $(( 5 * 1024 * 1024))

# Make sure we can create scrub progress data file
if [ -e /var/lib/btrfs ]; then
	test -w /var/lib/btrfs || _notrun '/var/lib/btrfs is not writable'
else
	test -w /var/lib || _notrun '/var/lib/btrfs cannot be created'
fi

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

uuid=$(findmnt -n -o UUID $SCRATCH_MNT)

devinfo_dir="/sys/fs/btrfs/${uuid}/devinfo/1"

# Check if we have the sysfs interface first.
if [ ! -f "${devinfo_dir}/scrub_speed_max" ]; then
	_notrun "No sysfs interface for scrub speed throttle"
fi

# Create a 2G file for later scrub workload.
# The 2G size is chosen to fit even DUP on a 5G disk.
$XFS_IO_PROG -f -c "pwrite -i /dev/urandom 0 2G" $SCRATCH_MNT/file | _filter_xfs_io

# Writeback above data, as scrub only verify the committed data.
sync

# The first scrub, mostly to grab the speed of the scrub.
$BTRFS_UTIL_PROG scrub start -B $SCRATCH_MNT >> $seqres.full

# We grab the rate from "scrub status" which supports raw bytes reporting
#
# The output looks like this:
# UUID:             62eaabc5-93e8-445f-b8a7-6f027934aea7
# Scrub started:    Thu Jan  5 14:59:12 2023
# Status:           finished
# Duration:         0:00:02
# Total to scrub:   1076166656
# Rate:             538083328/s
# Error summary:    no errors found
#
# What we care is that Rate line.
init_speed=$($BTRFS_UTIL_PROG scrub status --raw $SCRATCH_MNT | grep "Rate:" |\
	     $AWK_PROG '{print $2}' | cut -f1 -d\/)

# This can happen for older progs
if [ -z "$init_speed" ]; then
	_notrun "btrfs-progs doesn't support scrub rate reporting"
fi

# Cycle mount to drop any possible cache.
_scratch_cycle_mount

target_speed=$(( $init_speed / 2 ))
echo "$target_speed" > "${devinfo_dir}/scrub_speed_max"

# The second scrub, to check the throttled speed.
$BTRFS_UTIL_PROG scrub start -B $SCRATCH_MNT >> $seqres.full
speed=$($BTRFS_UTIL_PROG scrub status --raw $SCRATCH_MNT | grep "Rate:" |\
	     $AWK_PROG '{print $2}' | cut -f1 -d\/)

# We gave a +- 10% tolerance for the throttle
if [ "$speed" -gt "$(( $target_speed * 11 / 10 ))" -o \
     "$speed" -lt "$(( $target_speed * 9 / 10))" ]; then
	echo "scrub speed $speed Bytes/s is not properly throttled, target is $target_speed Bytes/s"
fi

# success, all done
status=0
exit