Re: [Question]nfs: should nfs timeout even with NFS_CS_NO_RETRANS_TIMEOUT ?

zhangjian (CG)
2026-03-12T04:19:55Z

On 3/6/2026 12:49 PM, Trond Myklebust wrote:
> 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.
>

NFSv4 spec said client should never retransmit, but not said client need
to wait forever. Maybe sunrpc should tell nfs -ETIMEOUT and nfs return
ERROR rather than retransmit.

> IOW: the problem here is your broken server, not the client.