Re: [PATCH 1/2] btrfs: test qgroup limit handling on fsverity rollback

[Qu Wenruo <wqu@suse.com>]

在 2026/9/15 15:08, Daniel Linjama 写道:
> Test that the subvolume and the filesystem stay writable when an fsverity
> enable and its rollback hit the qgroup limit, and that the subvolume is
> still reachable after a remount with no verity or orphan items left behind.
> 
> This exercises a bug fixed by the kernel patch with subject:
> "btrfs: handle lack of space when cleaning up verity items"
> 
> Assisted-by: LLM
> Signed-off-by: Daniel Linjama <daniel@dev.linjama.com>
> ---
>   tests/btrfs/354     | 131 ++++++++++++++++++++++++++++++++++++++++++++
>   tests/btrfs/354.out |   2 +
>   2 files changed, 133 insertions(+)
>   create mode 100755 tests/btrfs/354
>   create mode 100644 tests/btrfs/354.out
> 
> diff --git a/tests/btrfs/354 b/tests/btrfs/354
> new file mode 100755
> index 0000000..e3f6716
> --- /dev/null
> +++ b/tests/btrfs/354
> @@ -0,0 +1,131 @@
> +#! /bin/bash
> +# SPDX-License-Identifier: GPL-2.0
> +# Copyright (c) 2026 Daniel Linjama.  All Rights Reserved.
> +#
> +# FS QA Test 354
> +#
> +# Test that a failed fsverity enable in a subvolume whose qgroup is at its
> +# limit leaves the filesystem usable.
> +#
> +. ./common/preamble
> +_begin_fstest auto quick qgroup limit verity
> +
> +# Override the default cleanup function.
> +_cleanup()
> +{
> +	cd /
> +	_restore_fsverity_signatures
> +	rm -f $tmp.*
> +}
> +
> +# Import common functions.
> +. ./common/filter
> +. ./common/verity
> +
> +# real QA test starts here
> +
> +_require_scratch_verity
> +_require_btrfs_command inspect-internal dump-tree
> +_require_btrfs_command quota

_require_btrfs_command quota rescan -w


> +_require_no_compress
> +_require_scratch_size $((2 * 1024 * 1024))
> +_disable_fsverity_signatures
> +
> +_fixed_by_kernel_commit xxxxxxxxxxxx \
> +	"btrfs: handle lack of space when cleaning up verity items"
> +
> +subv=$SCRATCH_MNT/sub
> +target=$subv/target
> +
> +prepare()
> +{
> +	_scratch_mkfs_verity &>> $seqres.full
> +	_scratch_mount
> +	$BTRFS_UTIL_PROG quota enable $SCRATCH_MNT >> $seqres.full 2>&1
> +	_qgroup_rescan $SCRATCH_MNT >> $seqres.full 2>&1

Use "-w" option, or the rescan may not finish in time before the workload.

> +	_btrfs subvolume create $subv
> +	subvolid=$(_btrfs_get_subvolid $SCRATCH_MNT sub)
> +	$BTRFS_UTIL_PROG qgroup limit 200M 0/$subvolid $SCRATCH_MNT >> $seqres.full 2>&1
> +}
> +
> +create_target()
> +{
> +	dd if=/dev/zero of=$target bs=1M count=128 status=none
> +	sync
> +}
> +
> +fill_qgroup()
> +{
> +	local i=0
> +
> +	while dd if=/dev/zero of=$subv/filler.$i bs=1M count=4 status=none 2>/dev/null; do
> +		sync
> +		i=$((i + 1))
> +		[ $i -gt 200 ] && break

This is so hard to read.

Why not just a regular for loop?
And what the point of doing 200 loops?

If you just want to make sure to hit the quota limit, you don't need so 
many loops.
You can just do a 40MiB write (which should fail halfway), sync, retry 
the write until the write failed to write any bytes.

> +	done
> +	sync
> +	echo "fillers written: $i" >> $seqres.full
> +	$BTRFS_UTIL_PROG qgroup show -re $SCRATCH_MNT >> $seqres.full 2>&1
> +}
> +
> +enable_fsverity()
> +{
> +	if _fsv_enable $target >> $seqres.full 2>&1; then
> +		_notrun "could not exhaust the qgroup limit, verity enable succeeded"
> +	fi
> +}
> +
> +check_rollback()
> +{
> +	touch $SCRATCH_MNT/canary 2>> $seqres.full || \
> +		echo "filesystem was forced read-only by the failed verity enable"
> +	if $FSVERITY_PROG measure $target >> $seqres.full 2>&1; then
> +		echo "verity is enabled on the target after a failed enable"
> +	fi
> +}
> +
> +check_remount()
> +{
> +	_scratch_unmount
> +	_try_scratch_mount >> $seqres.full 2>&1 || \
> +		_fail "cannot mount the filesystem after the failed verity enable"
> +	ls $subv >/dev/null 2>> $seqres.full || \
> +		echo "cannot read the subvolume after the failed verity enable"
> +	dd if=$target of=/dev/null bs=1M count=1 status=none 2>> $seqres.full || \
> +		echo "cannot read the target file after the failed verity enable"
> +	_scratch_unmount
> +}
> +
> +check_leftover_items()
> +{
> +	local dump=$($BTRFS_UTIL_PROG inspect-internal dump-tree -t $subvolid $SCRATCH_DEV)
> +	local verity_items=$(echo "$dump" | grep -c 'VERITY_\(DESC\|MERKLE\)_ITEM')
> +	local orphans=$(echo "$dump" | grep -c 'ORPHAN_ITEM')
> +
> +	echo "$dump" >> $seqres.full
> +	[ "$verity_items" -eq 0 ] || \
> +		echo "$verity_items verity items left behind by the failed enable"
> +	[ "$orphans" -eq 0 ] || \
> +		echo "$orphans orphan items left behind by the failed enable"
> +}
> +
> +check_subvol_mount()
> +{
> +	_try_scratch_mount -o subvol=sub >> $seqres.full 2>&1 || \
> +		_fail "cannot mount the quota limited subvolume on its own"
> +}
> +
> +prepare
> +create_target
> +fill_qgroup
> +enable_fsverity
> +check_rollback
> +check_remount
> +check_leftover_items
> +check_subvol_mount
> +
> +echo "Silence is golden"
> +
> +# success, all done
> +status=0
> +exit
> diff --git a/tests/btrfs/354.out b/tests/btrfs/354.out
> new file mode 100644
> index 0000000..8bc7ecf
> --- /dev/null
> +++ b/tests/btrfs/354.out
> @@ -0,0 +1,2 @@
> +QA output created by 354
> +Silence is golden