Re: Status of delegations feature in NFSv4 client

Hi Shyam,

On Mon, Jun 15, 2026, at 11:55 PM, Shyam Prasad N wrote:
> Hi Trond,
>
> I wanted to understand if the file delegations feature on the NFSv4
> client is stable enough on Linux to support it in production
> environments? It looks like this feature has been around on the client
> for a really long time now. We tried running some workloads and file
> delegations offer really good perf benefits.

Like you've said above, file delegations have been around for a long time
and I would expect them to be stable for production environments.

>
> At the same time, I'd like to understand about the stability of
> directory delegations feature on NFS (I understand that this is much
> newer and only a part of NFSv4.2?). If there are gaps that exist
> today, please let me know. I'd be interested to submit patches to fix
> those issues.

Directory delegations are still fairly new, and are used with NFS v4.1
and v4.2. We have recallable directory delegations as of Linux 6.19. Work
is underway for supporting the CB_NOTIFY callback, which will hopefully
be upstream soon (I have patches written for client support, but I need
to find time to clean them up a bit more before posting them).

I hope this helps!
Anna

>
> -- 
> Regards,
> Shyam