Re: [PATCH v2] nfsd: Fix races between nfsd4_cb_release() and nfsd4_shutdown_callback()

[Trond Myklebust <trondmy@hammerspace.com>]

On Thu, 2019-11-07 at 17:27 -0500, J. Bruce Fields wrote:
> On Tue, Oct 29, 2019 at 05:47:05PM -0400, J. Bruce Fields wrote:
> > On Fri, Oct 25, 2019 at 11:33:36AM -0400, bfields wrote:
> > > On Fri, Oct 25, 2019 at 11:21:19AM -0400, J. Bruce Fields wrote:
> > > > I thought I was running v2, let me double-check....
> > > 
> > > Yes, with v2 I'm getting a hang on generic/013.
> > > 
> > > I checked quickly and didn't see anything interesting in the
> > > logs,
> > > otherwise I haven't done any digging.
> > 
> > Reproduceable just with ./check -nfs generic/013.  The last thing I
> > see
> > in wireshark is an asynchronous COPY call and reply.  Which means
> > it's
> > probably trying to do a CB_OFFLOAD.  Hm.
> 
> Oh, I think it just needs the following.
> 
> --b.
> 
> diff --git a/fs/nfsd/nfs4callback.c b/fs/nfsd/nfs4callback.c
> index fb71e7f9d0d9..e49604701a71 100644
> --- a/fs/nfsd/nfs4callback.c
> +++ b/fs/nfsd/nfs4callback.c
> @@ -1026,8 +1026,8 @@ static bool nfsd41_cb_get_slot(struct
> nfsd4_callback *cb, struct rpc_task *task)
>  			return false;
>  		}
>  		rpc_wake_up_queued_task(&clp->cl_cb_waitq, task);
> -		cb->cb_holds_slot = true;
>  	}
> +	cb->cb_holds_slot = true;
>  	return true;
>  }
>  

Doh! Thanks for spotting that.

-- 
Trond Myklebust
Linux NFS client maintainer, Hammerspace
trond.myklebust@hammerspace.com