Re: [PATCH v3] btrfs/255: add test for quota disable in parallel with balance

[Filipe Manana <fdmanana@kernel.org>]

On Wed, Jan 19, 2022 at 11:25:31AM +0900, Shin'ichiro Kawasaki wrote:
> Test quota disable during btrfs balance and confirm it does not cause
> kernel hang. This is a regression test for the problem reported to
> linux-btrfs list [1]. The hang was recreated using the test case and
> memory backed null_blk device with 5GB size as the scratch device.
> 
> [1] https://lore.kernel.org/linux-btrfs/20220115053012.941761-1-shinichiro.kawasaki@wdc.com/
> 
> Signed-off-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>

Reviewed-by: Filipe Manana <fdmanana@suse.com>

Looks good now, thanks.

> ---
> Changes from v2:
> * Added wait for balance operation finish
> 
> Changes from v1:
> * Put more stress by repeating quota enable/disable and btrfs balance
> * Reflected other comments on the list
> 
>  tests/btrfs/255     | 50 +++++++++++++++++++++++++++++++++++++++++++++
>  tests/btrfs/255.out |  2 ++
>  2 files changed, 52 insertions(+)
>  create mode 100755 tests/btrfs/255
>  create mode 100644 tests/btrfs/255.out
> 
> diff --git a/tests/btrfs/255 b/tests/btrfs/255
> new file mode 100755
> index 00000000..74aa9769
> --- /dev/null
> +++ b/tests/btrfs/255
> @@ -0,0 +1,50 @@
> +#! /bin/bash
> +# SPDX-License-Identifier: GPL-2.0
> +# Copyright (c) 2022 Western Digital Corporation or its affiliates.
> +#
> +# FS QA Test No. btrfs/255
> +#
> +# Confirm that disabling quota during balance does not hang
> +#
> +. ./common/preamble
> +_begin_fstest auto qgroup balance
> +
> +# real QA test starts here
> +_supported_fs btrfs
> +_require_scratch
> +
> +_scratch_mkfs >> $seqres.full 2>&1
> +_scratch_mount
> +
> +# Fill 40% of the device or 2GB
> +fill_percent=40
> +max_fillsize=$((2 * 1024 * 1024 * 1024))
> +
> +devsize=$(($(_get_device_size $SCRATCH_DEV) * 512))
> +fillsize=$((devsize * fill_percent / 100))
> +((fillsize > max_fillsize)) && fillsize=$max_fillsize
> +
> +fs=$((4096 * 1024))
> +for ((i = 0; i * fs < fillsize; i++)); do
> +	dd if=/dev/zero of=$SCRATCH_MNT/file.$i bs=$fs count=1 \
> +	   >> $seqres.full 2>&1
> +done
> +
> +# Run btrfs balance and quota enable/disable in parallel
> +_btrfs_stress_balance $SCRATCH_MNT >> $seqres.full &
> +balance_pid=$!
> +echo $balance_pid >> $seqres.full
> +for ((i = 0; i < 20; i++)); do
> +	$BTRFS_UTIL_PROG quota enable $SCRATCH_MNT
> +	$BTRFS_UTIL_PROG quota disable $SCRATCH_MNT
> +done
> +kill $balance_pid &> /dev/null
> +wait
> +# wait for the balance operation to finish
> +while ps aux | grep "balance start" | grep -qv grep; do
> +	sleep 1
> +done
> +
> +echo "Silence is golden"
> +status=0
> +exit
> diff --git a/tests/btrfs/255.out b/tests/btrfs/255.out
> new file mode 100644
> index 00000000..7eefb828
> --- /dev/null
> +++ b/tests/btrfs/255.out
> @@ -0,0 +1,2 @@
> +QA output created by 255
> +Silence is golden
> -- 
> 2.33.1
>