Re: [PATCH] btrfs: add test for subvolid reuse with squota

[Anand Jain <anand.jain@oracle.com>]

On 10/07/2024 01:51, Boris Burkov wrote:
> Squotas are likely to leave qgroups that outlive deleted subvolids.
> Before the kernel patch
> 2b8aa78cf127 ("btrfs: qgroup: fix qgroup id collision across mounts")
> this would lead to a repeated subvolid which would collide on an
> existing qgroup id and error out with EEXIST. In snapshot creation, this
> would lead to a read only fs.
> 
> Add a test which exercises the path that could create duplicate
> subvolids but with squotas enabled, which should avoid the trap.
> 
> Signed-off-by: Boris Burkov <boris@bur.io>


Reviewed-by: Anand Jain <anand.jain@oracle.com>

Applied.

Thanks, Anand

> ---
>   tests/btrfs/331     | 45 +++++++++++++++++++++++++++++++++++++++++++++
>   tests/btrfs/331.out |  2 ++
>   2 files changed, 47 insertions(+)
>   create mode 100755 tests/btrfs/331
>   create mode 100644 tests/btrfs/331.out
> 
> diff --git a/tests/btrfs/331 b/tests/btrfs/331
> new file mode 100755
> index 000000000..8a99d5527
> --- /dev/null
> +++ b/tests/btrfs/331
> @@ -0,0 +1,45 @@
> +#! /bin/bash
> +# SPDX-License-Identifier: GPL-2.0
> +# Copyright (c) 2024 Meta Platforms, Inc.  All Rights Reserved.
> +#
> +# FS QA Test 331
> +#
> +# Test that btrfs does not recycle subvolume ids across remounts in a way that
> +# breaks squotas.
> +#
> +. ./common/preamble
> +_begin_fstest auto quick qgroup snapshot
> +
> +_fixed_by_kernel_commit 2b8aa78cf127 \
> +	"btrfs: qgroup: fix qgroup id collision across mounts"
> +
> +. ./common/btrfs
> +_supported_fs btrfs
> +_require_scratch_enable_simple_quota
> +
> +_scratch_mkfs >> $seqres.full
> +_scratch_mount
> +$BTRFS_UTIL_PROG quota enable --simple $SCRATCH_MNT
> +
> +# Create a gap in the subvolume IDs
> +sv=$SCRATCH_MNT/sv
> +for i in $(seq 100); do
> +	$BTRFS_UTIL_PROG subvolume create $sv.$i >> $seqres.full
> +done
> +for i in $(seq 50 100); do
> +	$BTRFS_UTIL_PROG subvolume delete $sv.$i >> $seqres.full
> +done
> +
> +# Cycle mount triggers reading the tree_root's free objectid.
> +_scratch_cycle_mount
> +
> +# Create snapshots that could go into the used subvolid space.
> +$BTRFS_UTIL_PROG subvolume create $sv.BOOM >> $seqres.full
> +for i in $(seq 10); do
> +	$BTRFS_UTIL_PROG subvolume snapshot $sv.BOOM $sv.BOOM.$i >> $seqres.full
> +done
> +
> +# success, all done
> +echo "Silence is golden"
> +status=0
> +exit
> diff --git a/tests/btrfs/331.out b/tests/btrfs/331.out
> new file mode 100644
> index 000000000..0097e61d8
> --- /dev/null
> +++ b/tests/btrfs/331.out
> @@ -0,0 +1,2 @@
> +QA output created by 331
> +Silence is golden