Re: [PATCH v3 1/3] fs: add umount notifier chain for filesystem unmount notification

[Chuck Lever <cel@kernel.org>]

On 3/1/26 11:09 PM, NeilBrown wrote:
> On Mon, 02 Mar 2026, Chuck Lever wrote:
>>
>> On Sun, Mar 1, 2026, at 1:09 PM, Amir Goldstein wrote:
>>> On Sun, Mar 1, 2026 at 6:21 PM Chuck Lever <cel@kernel.org> wrote:
>>>> Perhaps that description nails down too much implementation detail,
>>>> and it might be stale. A broader description is this user story:
>>>>
>>>> "As a system administrator, I'd like to be able to unexport an NFSD
>>>
>>> Doesn't "unexporting" involve communicating to nfsd?
>>> Meaning calling to svc_export_put() to path_put() the
>>> share root path?
>>>
>>>> share that is being accessed by NFSv4 clients, and then unmount it,
>>>> reliably (for example, via automation). Currently the umount step
>>>> hangs if there are still outstanding delegations granted to the NFSv4
>>>> clients."
>>>
>>> Can't svc_export_put() be the trigger for nfsd to release all resources
>>> associated with this share?
>>
>> Currently unexport does not revoke NFSv4 state. So, that would
>> be a user-visible behavior change. I suggested that approach a
>> few months ago to linux-nfs@ and there was push-back.
>>
> 
> Could we add a "-F" or similar flag to "exportfs -u" which implements the
> desired semantic?  i.e.  asking nfsd to release all locks and close all
> state on the filesystem.

That meets my needs, but should be passed by the linux-nfs@ review
committee.

-F could probably just use the existing "unlock filesystem" API
after it does the unexport.


-- 
Chuck Lever