Re: [PATCH v6 06/11] fstests: verify f_fsid for cloned filesystems

On 29/5/26 12:39, Darrick J. Wong wrote:
> On Thu, May 28, 2026 at 12:05:37PM +0800, Anand Jain wrote:
>> Verify that the cloned filesystem provides an f_fsid that is persistent
>> across mount cycles, yet unique from the original filesystem's f_fsid.
> 
> Might want to add that last part to the test description itself, because
> otherwise I don't know what 'verify' means.
> 


Looks like there's going to be v7, I have updated the test description..

-------
+# Check that the cloned filesystem provides an f_fsid that is persistent
+# across mount cycles if the block device maj:min remains unchanged.
-------

>> Signed-off-by: Anand Jain <[email protected]>
>> ---
>>  tests/generic/802     | 67 +++++++++++++++++++++++++++++++++++++++++++
>>  tests/generic/802.out |  7 +++++
>>  2 files changed, 74 insertions(+)
>>  create mode 100644 tests/generic/802
>>  create mode 100644 tests/generic/802.out
>>
>> diff --git a/tests/generic/802 b/tests/generic/802
>> new file mode 100644
>> index 000000000000..653e74e11b53
>> --- /dev/null
>> +++ b/tests/generic/802
>> @@ -0,0 +1,67 @@
>> +#! /bin/bash
>> +# SPDX-License-Identifier: GPL-2.0
>> +# Copyright (c) 2026 Anand Jain <[email protected]>.  All Rights Reserved.
>> +#
>> +# FS QA Test 802
>> +# Verify f_fsid and s_uuid of cloned filesystems across mount cycle.
>> +
>> +. ./common/preamble
>> +
>> +_begin_fstest auto quick mount clone
>> +
>> +_require_test
>> +_require_block_device $TEST_DEV
>> +_require_loop
>> +
>> +[ "$FSTYP" = "btrfs" ] && _fixed_by_kernel_commit xxxxxxxxxxxx \
>> +	"btrfs: use on-disk uuid for s_uuid in temp_fsid mounts"
>> +[ "$FSTYP" = "btrfs" ] && _fixed_by_kernel_commit xxxxxxxxxxxx \
>> +	"btrfs: derive f_fsid from on-disk fsuuid and dev_t"
> 
> _fixed_by_fs_commit?
> 

Oh right! I completely forgot about the new helper _fixed_by_fs_commit.
Now fixed. Thanks.

-[ "$FSTYP" = "btrfs" ] && _fixed_by_kernel_commit xxxxxxxxxxxx \
+_fixed_by_fs_commit btrfs xxxxxxxxxxxx \
         "btrfs: use on-disk uuid for s_uuid in temp_fsid mounts"
-[ "$FSTYP" = "btrfs" ] && _fixed_by_kernel_commit xxxxxxxxxxxx \
+_fixed_by_fs_commit btrfs xxxxxxxxxxxx \
         "btrfs: derive f_fsid from on-disk fsuuid and dev_t"

>> +
>> +_cleanup()
>> +{
>> +	cd /
>> +	rm -r -f $tmp.*
>> +	umount $mnt1 $mnt2 2>/dev/null
>> +	_loop_image_destroy "${devs[@]}" 2> /dev/null
>> +}
>> +
>> +# 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
>> +
>> +# Mount both filesystems simultaneously using mandatory clone mount options
>> +_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]} $mnt2 || \
>> +						_fail "Failed to mount dev2"
>> +
>> +# Capture baseline filesystem IDs for comparison
>> +fsid_scratch=$(stat -f -c "%i" $mnt1)
>> +fsid_clone=$(stat -f -c "%i" $mnt2)
>> +
>> +echo "**** fsid initially ****"
>> +echo $fsid_scratch | sed -e "s/$fsid_scratch/FSID_SCRATCH/g"
>> +echo $fsid_clone | sed -e "s/$fsid_clone/FSID_CLONE/g"
> 
> Why echo only to sed?
> 

I tried to keep both the .out log and the script readable.
Since a bare echo FSID_SCRATCH and echo FSID_CLONE has no
clear reference to $fsid_scratch and $fsid_clone, I just
added a little extra code around them.

However, I'm completely fine with removing both viz,
expected output and its script (for the first mount part).
As I'm pretty sure there will be a v7 now, ;-)
I can make those changes.

Thanks, Anand

>> +
>> +# Verify that the fsids remain stable after a mount cycle, even when the
>> +# mount order is reversed.
>> +echo "**** fsid after 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"
>> +
>> +# Compare post mount-cycle values against the baseline
>> +stat -f -c "%i" $mnt1 | sed -e "s/$fsid_scratch/FSID_SCRATCH/g"
>> +stat -f -c "%i" $mnt2 | sed -e "s/$fsid_clone/FSID_CLONE/g"
>> +
>> +status=0
>> +exit
>> diff --git a/tests/generic/802.out b/tests/generic/802.out
>> new file mode 100644
>> index 000000000000..d1e008f122bb
>> --- /dev/null
>> +++ b/tests/generic/802.out
>> @@ -0,0 +1,7 @@
>> +QA output created by 802
>> +**** fsid initially ****
>> +FSID_SCRATCH
>> +FSID_CLONE
>> +**** fsid after mount cycle ****
>> +FSID_SCRATCH
>> +FSID_CLONE
>> -- 
>> 2.43.0
>>
>>