Re: [PATCH v2] fstests: test premature ENOSPC in zoned garbage collection

On Tue, Apr 14, 2026 at 2:50 PM Johannes Thumshirn
<[email protected]> 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 <[email protected]>
> ---
> Changes to v1:
> - Rebased onto patches-in-queue
> - Use "generic/999" to avoid any conflicts
> - Change the number of loops to number of seq zones
> - Remove bogus "2>&1"
>
> Link to v1:
> https://lore.kernel.org/all/[email protected]/
>
>
>  tests/generic/999     | 48 +++++++++++++++++++++++++++++++++++++++++++
>  tests/generic/999.out |  2 ++
>  2 files changed, 50 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..4ac6c0ff935c
> --- /dev/null
> +++ b/tests/generic/999
> @@ -0,0 +1,48 @@
> +#! /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 bugifx.
> +
> +. ./common/preamble
> +_begin_fstest auto quick zone
> +
> +. ./common/filter
> +
> +_require_scratch_size $((16 * 1024 * 1024))
> +_require_zoned_device "$SCRATCH_DEV"
> +
> +# This test requires specific data space usage, skip if we have compression
> +# enabled.
> +_require_no_compress
> +
> +
> +_fixed_by_fs_commit XXXXXXXXXXXX \
> +       "btrfs: zoned: cap delayed refs metadata reservation to avoid overcommit"
> +_fixed_by_fs_commit XXXXXXXXXXXX \
> +       "btrfs: zoned: move partially zone_unusable block groups to reclaim list"

Already in Linus' tree, commit hash 258e46a6385c.

> +_fixed_by_fs_commit XXXXXXXXXXXX \
> +       "btrfs: zoned: add zone reclaim flush state for DATA space_info"

Also in Linus' tree, commit hash e2a7fd22378f.

> +
> +
> +_scratch_mkfs_sized $((16 * 1024 * 1024 * 1024)) &>>$seqres.full
> +_scratch_mount
> +
> +blocks="$(df -TB 1G $SCRATCH_DEV |\
> +       $AWK_PROG -v fstyp="$FSTYP" 'match($2, fstyp) {print $3}')"
> +
> +loops=$(echo "$blocks * 4 - 2" | bc)

nit: why pipe to bc? Wouldn't a simple bash expression like the following work?

loops=$(( blocks * 4 - 2 ))

Otherwise it looks fine to me, thanks.

> +
> +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
>
>