Re: [PATCH v8 09/13] fstests: verify libblkid resolution of duplicate UUIDs

[Zorro Lang <zlang@kernel.org>]

On Sat, Jul 25, 2026 at 03:39:06PM +0800, Anand Jain wrote:
> Verify how findmnt, df (libblkid) resolve device paths when multiple

I didn't find the `df` test part in this test case.

> block devices share the same FSUUID.
> 
> Signed-off-by: Anand Jain <asj@kernel.org>
> ---
>  tests/generic/803     | 72 +++++++++++++++++++++++++++++++++++++++++++
>  tests/generic/803.out |  6 ++++
>  2 files changed, 78 insertions(+)
>  create mode 100644 tests/generic/803
>  create mode 100644 tests/generic/803.out
> 
> diff --git a/tests/generic/803 b/tests/generic/803
> new file mode 100644
> index 000000000000..77901592366c
> --- /dev/null
> +++ b/tests/generic/803
> @@ -0,0 +1,72 @@
> +#! /bin/bash
> +# SPDX-License-Identifier: GPL-2.0
> +# Copyright (c) 2026 Anand Jain <asj@kernel.org>.  All Rights Reserved.
> +#
> +# FS QA Test 803
> +# Check if the mountinfo based findmnt would resolve to the common uuid
> +# as per the blkid (libblkid based).
> +
> +. ./common/preamble
> +. ./common/filter
> +
> +_begin_fstest auto quick mount clone
> +
> +_require_test
> +_require_block_device $TEST_DEV
> +_require_loop
> +
> +_cleanup()
> +{
> +	cd /
> +	rm -r -f $tmp.*
> +	umount $mnt1 $mnt2 2>/dev/null
> +	_loop_image_destroy "${devs[@]}" 2> /dev/null
> +}
> +
> +# Normalize pool devices and mount points names
> +filter_pool()
> +{
> +	sed -e "s|${devs[0]}|DEV1|g" -e "s|${mnt1}|MNT1|g" \
> +	    -e "s|${devs[1]}|DEV2|g" -e "s|${mnt2}|MNT2|g" | _filter_spaces
> +}
> +
> +# Setup base loop device and its clone
> +devs=()
> +_loop_image_create_clone devs
> +mkdir -p $TEST_DIR/$seq
> +mnt1=$TEST_DIR/$seq/mnt1
> +mnt2=$TEST_DIR/$seq/mnt2
> +mkdir -p $mnt1
> +mkdir -p $mnt2
> +
> +# Get the uuid from the source device
> +fsuuid=$(blkid -s UUID -o value ${devs[0]})
> +
> +# Mount both identical UUID filesystems simultaneously
> +_mount $(_common_dev_mount_options) $(_clone_mount_option) ${devs[0]} $mnt1 || \
> +						_fail "Failed to mount dev1"
> +_mount $(_common_dev_mount_options) $(_clone_mount_option) ${devs[1]} $mnt2 || \
> +						_fail "Failed to mount dev2"
> +
> +findmnt -o SOURCE,TARGET,UUID "${devs[0]}" | tail -n +2 | \
> +				sed -e "s/${fsuuid}/FSUUID/g" | filter_pool

findmnt -n (or --noheadings) can be used here (and below) to avoid piping to
`tail -n +2`.

> +findmnt -o SOURCE,TARGET,UUID "${devs[1]}" | tail -n +2 | \
> +				sed -e "s/${fsuuid}/FSUUID/g" | filter_pool

Same here

> +
> +# Btrfs assigned a random uuid for the clone fs before the fix.
> +# Cycle mounts and reverse the initialization (source and clone fs) order.
> +echo "**** mount cycle ****"
> +_unmount $mnt1
> +_unmount $mnt2
> +_mount $(_common_dev_mount_options) $(_clone_mount_option) ${devs[1]} $mnt2 || \
> +						_fail "Failed to mount dev2"
> +_mount $(_common_dev_mount_options) $(_clone_mount_option) ${devs[0]} $mnt1 || \
> +						_fail "Failed to mount dev1"
> +
> +findmnt -o SOURCE,TARGET,UUID "${devs[0]}" | tail -n +2 | \
> +				sed -e "s/${fsuuid}/FSUUID/g" | filter_pool

Same here

> +findmnt -o SOURCE,TARGET,UUID "${devs[1]}" | tail -n +2 | \
> +				sed -e "s/${fsuuid}/FSUUID/g" | filter_pool

Same here

> +
> +status=0
> +exit

_exit 0

> diff --git a/tests/generic/803.out b/tests/generic/803.out
> new file mode 100644
> index 000000000000..3a130c662430
> --- /dev/null
> +++ b/tests/generic/803.out
> @@ -0,0 +1,6 @@
> +QA output created by 803
> +DEV1 MNT1 FSUUID
> +DEV2 MNT2 FSUUID
> +**** mount cycle ****
> +DEV1 MNT1 FSUUID
> +DEV2 MNT2 FSUUID
> -- 
> 2.43.0
>