Re: [PATCH v3 3/9] fstests: add test for inotify isolation on cloned devices

On Mon, Apr 27, 2026 at 12:20 PM Anand Jain <[email protected]> wrote:
>
> Add a new test, to verify that the kernel correctly differentiates between
> two block devices sharing the same FSID/UUID.
>
> Signed-off-by: Anand Jain <[email protected]>

Reviewed-by: Amir Goldstein <[email protected]>

> ---
>  common/config         |  1 +
>  tests/generic/800     | 88 +++++++++++++++++++++++++++++++++++++++++++
>  tests/generic/800.out |  7 ++++
>  3 files changed, 96 insertions(+)
>  create mode 100644 tests/generic/800
>  create mode 100644 tests/generic/800.out
>
> diff --git a/common/config b/common/config
> index 4fd4c2c8af11..605a57947a40 100644
> --- a/common/config
> +++ b/common/config
> @@ -242,6 +242,7 @@ export BTRFS_MAP_LOGICAL_PROG=$(type -P btrfs-map-logical)
>  export PARTED_PROG="$(type -P parted)"
>  export XFS_PROPERTY_PROG="$(type -P xfs_property)"
>  export FSCRYPTCTL_PROG="$(type -P fscryptctl)"
> +export INOTIFYWAIT_PROG="$(type -P inotifywait)"
>
>  # udev wait functions.
>  #
> diff --git a/tests/generic/800 b/tests/generic/800
> new file mode 100644
> index 000000000000..16bc1159a2e1
> --- /dev/null
> +++ b/tests/generic/800
> @@ -0,0 +1,88 @@
> +#! /bin/bash
> +# SPDX-License-Identifier: GPL-2.0
> +# Copyright (c) 2026 Anand Jain <[email protected]>.  All Rights Reserved.
> +#
> +# FS QA Test 800
> +#
> +# Verify if the kernel or userspace becomes confused when two block devices
> +# share the same fid/fsid/uuid. Create inotify on both original and cloned
> +# filesystem. Monitor the notification in the respective logs.
> +
> +. ./common/preamble
> +
> +_begin_fstest auto quick mount clone
> +
> +_require_test
> +_require_loop
> +_require_command "$INOTIFYWAIT_PROG" inotifywait
> +
> +_cleanup()
> +{
> +       cd /
> +       [[ -n $pid1 ]] && { kill -TERM "$pid1" 2> /dev/null; wait $pid1; }
> +       [[ -n $pid2 ]] && { kill -TERM "$pid2" 2> /dev/null; wait $pid2; }
> +       rm -r -f $tmp.*
> +       _unmount $mnt1 2>/dev/null
> +       _unmount $mnt2 2>/dev/null
> +       _loop_image_destroy "${devs[@]}" 2> /dev/null
> +}
> +
> +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
> +
> +_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]} $mnt2 || \
> +                                               _fail "Failed to mount dev2"
> +
> +log1=$tmp.inotify1
> +log2=$tmp.inotify2
> +
> +pid1=""
> +pid2=""
> +echo "Setup inotify watchers on both mnt1 and mnt2"
> +$INOTIFYWAIT_PROG -m -e create --format '%f' $mnt1 > $log1 2>&1 &
> +pid1=$!
> +$INOTIFYWAIT_PROG -m -e create --format '%f' $mnt2 > $log2 2>&1 &
> +pid2=$!
> +sleep 2
> +
> +echo "Trigger file creation on mnt1"
> +touch $mnt1/file_on_mnt1
> +sync
> +sleep 1
> +
> +echo "Trigger file creation on mnt2"
> +touch $mnt2/file_on_mnt2
> +sync
> +sleep 1
> +
> +echo "Verify inotify isolation"
> +kill $pid1 $pid2
> +wait $pid1 $pid2 2>/dev/null
> +pid1=""
> +pid2=""
> +
> +if grep -q "file_on_mnt1" $log1 && ! grep -q "file_on_mnt2" $log1; then
> +       echo "SUCCESS: mnt1 events isolated."
> +else
> +       echo "FAIL: mnt1 inotify confusion!"
> +       [ ! -s $log1 ] && echo "  - mnt1 received no events."
> +       grep -q "file_on_mnt2" $log1 && echo "  - mnt1 received event from mnt2."
> +fi
> +
> +if grep -q "file_on_mnt2" $log2 && ! grep -q "file_on_mnt1" $log2; then
> +       echo "SUCCESS: mnt2 events isolated."
> +else
> +       echo "FAIL: mnt2 inotify confusion!"
> +       [ ! -s $log2 ] && echo "  - mnt2 received no events."
> +       grep -q "file_on_mnt1" $log2 && echo "  - mnt2 received event from mnt1."
> +fi
> +
> +status=0
> +exit
> diff --git a/tests/generic/800.out b/tests/generic/800.out
> new file mode 100644
> index 000000000000..b10842a31210
> --- /dev/null
> +++ b/tests/generic/800.out
> @@ -0,0 +1,7 @@
> +QA output created by 800
> +Setup inotify watchers on both mnt1 and mnt2
> +Trigger file creation on mnt1
> +Trigger file creation on mnt2
> +Verify inotify isolation
> +SUCCESS: mnt1 events isolated.
> +SUCCESS: mnt2 events isolated.
> --
> 2.43.0
>