Re: [PATCH v4] fstests: test premature ENOSPC in zoned garbage collection

[Zorro Lang <zorro.lang@gmail.com>]

On Wed, Apr 15, 2026 at 12:40:15PM +0200, Johannes Thumshirn wrote:
> This test stresses garbage collection in zoned file systems by
> constantly overwriting the same file. It is inspired by a reproducer for
> a btrfs bugifx.
> 
> Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
> ---
> Changes to v3:
> - Distinguish between SCRATCH_DEV and SCRATCH_RTDEV so both BTRFS and
>   XFS work
> - Fix typo
> 
> Link to v3:
> https://lore.kernel.org/r/20260414143341.167875-1-johannes.thumshirn@wdc.com
> 
>  tests/generic/999     | 53 +++++++++++++++++++++++++++++++++++++++++++
>  tests/generic/999.out |  2 ++
>  2 files changed, 55 insertions(+)
>  create mode 100755 tests/generic/999
>  create mode 100644 tests/generic/999.out
> 
> diff --git a/tests/generic/999 b/tests/generic/999
> new file mode 100755
> index 000000000000..d3b38b676d37
> --- /dev/null
> +++ b/tests/generic/999
> @@ -0,0 +1,53 @@
> +#! /bin/bash
> +# SPDX-License-Identifier: GPL-2.0
> +# Copyright (c) 2026 Western Digital Corporation.  All Rights Reserved.
> +#
> +# FS QA Test 999
> +#
> +# This test stresses garbage collection in zoned file systems by constantly
> +# overwriting the same file. It is inspired by a reproducer for a btrfs bugfix.
> +
> +. ./common/preamble
> +_begin_fstest auto quick zone
> +
> +. ./common/filter
> +
> +
> +if [ -b "$SCRATCH_RTDEV" ]; then
> +	zoned_dev=$SCRATCH_RTDEV
> +else
> +	zoned_dev=$SCRATCH_DEV
> +fi


I'll move above lines further down, specifically after the _require_scratch_size
call, when I merge this patch. Others make sense to me.

Reviewed-by: Zorro Lang <zlang@kernel.org>

> +
> +_require_scratch_size $((16 * 1024 * 1024))
> +_require_zoned_device "$zoned_dev"
> +_require_command "$BLKZONE_PROG" blkzone
> +
> +# This test requires specific data space usage, skip if we have compression
> +# enabled.
> +_require_no_compress
> +
> +_fixed_by_fs_commit btrfs 7bcb04de982f \
> +	"btrfs: zoned: cap delayed refs metadata reservation to avoid overcommit"
> +_fixed_by_fs_commit btrfs 258e46a6385c \
> +	"btrfs: zoned: move partially zone_unusable block groups to reclaim list"
> +_fixed_by_fs_commit btrfs e2a7fd22378f \
> +	"btrfs: zoned: add zone reclaim flush state for DATA space_info"
> +
> +_scratch_mkfs_sized $((16 * 1024 * 1024 * 1024)) &>>$seqres.full
> +_scratch_mount
> +
> +# Overwrite the data "number of seq zones" times, this is arbitrarily chosen
> +# but triggers the original bug reliably
> +loops=$($BLKZONE_PROG report $zoned_dev | grep -c "SEQ_WRITE_REQUIRED")
> +
> +for (( i = 0; i < $loops; i++ )); do
> +	dd if=/dev/zero of=$SCRATCH_MNT/test bs=1M count=1024 status=none
> +	if [ $? -ne 0 ]; then
> +		_fail "Failed writing on iteration $i"
> +	fi
> +done
> +
> +echo "Silence is golden"
> +# success, all done
> +_exit 0
> diff --git a/tests/generic/999.out b/tests/generic/999.out
> new file mode 100644
> index 000000000000..3b276ca804fc
> --- /dev/null
> +++ b/tests/generic/999.out
> @@ -0,0 +1,2 @@
> +QA output created by 999
> +Silence is golden
> -- 
> 2.53.0
> 
>