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Date:   Wed, 27 Apr 2022 12:12:21 -0400
From:   "J. Bruce Fields" <bfields@fieldses.org>
To:     Dai Ngo <dai.ngo@oracle.com>
Cc:     chuck.lever@oracle.com, jlayton@redhat.com,
        viro@zeniv.linux.org.uk, linux-nfs@vger.kernel.org,
        linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH RFC v22 1/7] NFSD: add courteous server support for
 thread with only delegation
Message-ID: <20220427161221.GD13471@fieldses.org>
References: <1651049573-29552-1-git-send-email-dai.ngo@oracle.com>
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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.