Re: [Question]nfs: never returned delegation

Trond Myklebust
2026-03-06T04:49:43Z

On Fri, 2026-03-06 at 10:46 +0800, zhangjian (CG) wrote:
> Hi experts on NFS:
>
> Recently we meet an error:
> 1.Nfs wait for sunrpc
> 2.Sunrpc send OPEN message and hang the rpc task onto sunrpc pending
> queue.
> 3.Server never reply, and since NFS_CS_NO_RETRANS_TIMEOUT is forced
> and
> connection is ESTABLISHED, task will never be retransmitted.
> This cause procedures waiting on this file hang forever.
> I know using "umount -f " to kill rpc task works. And the key to the
> problem most likely lies in the network layer. But should nfs
> retransmit
> it after waiting for so long?
>
> Wish for reply. Thanks
>
> Zhangjian
>
Please read the NFSv4 spec. It very clearly states that the client
should never retransmit unless the connection breaks.

IOW: the problem here is your broken server, not the client.
--
Trond Myklebust
Linux NFS client maintainer, Hammerspace
trondmy@kernel.org, trond.myklebust@hammerspace.com