Re: [PATCH RFC v22 1/7] NFSD: add courteous server support for thread with only delegation

["J. Bruce Fields" <bfields@fieldses.org>]

On Wed, Apr 27, 2022 at 01:52:47AM -0700, Dai Ngo wrote:
> +	if (!try_to_expire_client(clp)) {
> +		nn = net_generic(clp->net, nfsd_net_id);
> +		mod_delayed_work(laundry_wq, &nn->laundromat_work, 0);
> +	}
...
> +static inline bool try_to_expire_client(struct nfs4_client *clp)
> +{
> +	bool ret;
> +
> +	ret = NFSD4_ACTIVE ==
> +		cmpxchg(&clp->cl_state, NFSD4_COURTESY, NFSD4_EXPIRABLE);
> +	return ret;
> +}

Hm, this feels a little backwards to me.  I'd expect
"try_to_expire_client" to return true on success.  Maybe call it
"client_is_expirable()" to make that clear?  Or stick with
"try_to_expire_client and make it return 0/-EAGAIN.

If "NFSD4_ACTIVE != cmpxchg(...)" is too confusing, I don't think we
really even need the atomic return of the previous value, I think it
would be OK just to do:

	cmpschg(&clp->cl_state, NFSD4_COURTESY, NFSD4_EXPIRABLE);
	return clp->cl_state == NFSD4_EXPIRABLE;

--b.