Re: [PATCH v2 1/6] overlay: workaround libmount failure to remount,ro

["André Almeida" <andrealmeid@igalia.com>]

Hi Amir,

On 6/6/25 09:35, Amir Goldstein wrote:
> On Fri, Jun 6, 2025 at 3:12 AM Zorro Lang <zlang@redhat.com> wrote:
>> On Thu, Jun 05, 2025 at 08:30:53PM +0200, Amir Goldstein wrote:
>>> On Thu, Jun 5, 2025 at 7:51 PM Zorro Lang <zlang@redhat.com> wrote:
>>>> On Tue, Jun 03, 2025 at 12:07:40PM +0200, Amir Goldstein wrote:
>>>>> libmount >= v1.39 calls several unneeded fsconfig() calls to reconfigure
>>>>> lowerdir/upperdir when user requests only -o remount,ro.
>>>>>
>>>>> Those calls fail because overlayfs does not allow making any config
>>>>> changes with new mount api, besides MS_RDONLY.
>>>>>
>>>>> We workaround this problem with --options-mode ignore.
>>>>>
>>>>> Reported-by: André Almeida <andrealmeid@igalia.com>
>>>>> Suggested-by: Karel Zak <kzak@redhat.com>
>>>>> Link: https://lore.kernel.org/linux-fsdevel/20250521-ovl_ro-v1-1-2350b1493d94@igalia.com/
>>>>> Link: https://lore.kernel.org/fstests/CAJfpegtJ3SDKmC80B4AfWiC3JmtWdW2+78fRZVtsuhe-wSRPvg@mail.gmail.com/
>>>>> Signed-off-by: Amir Goldstein <amir73il@gmail.com>
>>>>> ---
>>>>>
>>>>> Changes since v1 [1]:
>>>>> - Change workaround from LIBMOUNT_FORCE_MOUNT2 to --options-mode=ignore
>>>>>
>>>>> [1] https://lore.kernel.org/fstests/20250526143500.1520660-1-amir73il@gmail.com/
>>>> I'm not sure if I understand clearly. Does overlay list are fixing this issue
>>>> on kernel side, then providing a workaround to fstests to avoid the issue be
>>>> triggered too?
>>>>
>>> Noone agreed to fix it on the kernel side.
>>> At least not yet.
>> If so, I have two questions:)
>> 1) Will overlay fix it on kernel or mount util side?
> This is not known at this time.

Do you know how calling fsconfig() in a "redundant" way behaves in other 
filesystems? Do they allow to call fsconfig() calls that doesn't change 
the state, like a noop?