linux-kernel - [PATCH 3/3] nfsd: allow passing in array of thread counts via netlink

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Message-Id: <20240604-nfsd-next-v1-3-8df686ae61de@kernel.org>
Date: Tue, 04 Jun 2024 17:07:56 -0400
From: Jeff Layton <jlayton@...nel.org>
To: Chuck Lever <chuck.lever@...cle.com>, Neil Brown <neilb@...e.de>, 
 Olga Kornievskaia <kolga@...app.com>, Dai Ngo <Dai.Ngo@...cle.com>, 
 Tom Talpey <tom@...pey.com>, "David S. Miller" <davem@...emloft.net>, 
 Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, 
 Paolo Abeni <pabeni@...hat.com>
Cc: Trond Myklebust <trond.myklebust@...merspace.com>, 
 Anna Schumaker <anna@...nel.org>, linux-nfs@...r.kernel.org, 
 linux-kernel@...r.kernel.org, netdev@...r.kernel.org, 
 Jeff Layton <jlayton@...nel.org>
Subject: [PATCH 3/3] nfsd: allow passing in array of thread counts via
 netlink

Now that nfsd_svc can handle an array of thread counts, fix up the
netlink threads interface to construct one from the netlink call
and pass it through so we can start a pooled server the same way we
would start a normal one.

Note that any unspecified values in the array are considered zeroes,
so it's possible to shut down a pooled server by passing in a short
array that has only zeros, or even an empty array.

Signed-off-by: Jeff Layton <jlayton@...nel.org>
---
 fs/nfsd/nfsctl.c | 33 +++++++++++++++++++++------------
 fs/nfsd/nfssvc.c | 12 +++++++++++-
 2 files changed, 32 insertions(+), 13 deletions(-)

diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c
index 121b866125d4..54b98e569740 100644
--- a/fs/nfsd/nfsctl.c
+++ b/fs/nfsd/nfsctl.c
@@ -1673,7 +1673,8 @@ int nfsd_nl_rpc_status_get_done(struct netlink_callback *cb)
  */
 int nfsd_nl_threads_set_doit(struct sk_buff *skb, struct genl_info *info)
 {
-	int nthreads = 0, count = 0, nrpools, ret = -EOPNOTSUPP, rem;
+	int *nthreads, count = 0, nrpools, ret = -EOPNOTSUPP;
+	int rem, i, total = 0;
 	struct net *net = genl_info_net(info);
 	struct nfsd_net *nn = net_generic(net, nfsd_net_id);
 	const struct nlattr *attr;
@@ -1690,15 +1691,22 @@ int nfsd_nl_threads_set_doit(struct sk_buff *skb, struct genl_info *info)

 	mutex_lock(&nfsd_mutex);

-	nrpools = nfsd_nrpools(net);
-	if (nrpools && count > nrpools)
-		count = nrpools;
-
-	/* XXX: make this handle non-global pool-modes */
-	if (count > 1)
+	nrpools = max(count, nfsd_nrpools(net));
+	nthreads = kcalloc(nrpools, sizeof(int), GFP_KERNEL);
+	if (!nthreads) {
+		ret = -ENOMEM;
 		goto out_unlock;
+	}
+
+	i = 0;
+	nlmsg_for_each_attr(attr, info->nlhdr, GENL_HDRLEN, rem) {
+		if (nla_type(attr) == NFSD_A_SERVER_THREADS) {
+			total += nthreads[i++] = nla_get_u32(attr);
+			if (i >= count)
+				break;
+		}
+	}

-	nthreads = nla_get_u32(info->attrs[NFSD_A_SERVER_THREADS]);
 	if (info->attrs[NFSD_A_SERVER_GRACETIME] ||
 	    info->attrs[NFSD_A_SERVER_LEASETIME] ||
 	    info->attrs[NFSD_A_SERVER_SCOPE]) {
@@ -1732,12 +1740,13 @@ int nfsd_nl_threads_set_doit(struct sk_buff *skb, struct genl_info *info)
 			scope = nla_data(attr);
 	}

-	ret = nfsd_svc(1, &nthreads, net, get_current_cred(), scope);
-
+	ret = nfsd_svc(nrpools, nthreads, net, get_current_cred(), scope);
+	if (ret > 0)
+		ret = 0;
 out_unlock:
 	mutex_unlock(&nfsd_mutex);
-
-	return ret == nthreads ? 0 : ret;
+	kfree(nthreads);
+	return ret;
 }

 /**
diff --git a/fs/nfsd/nfssvc.c b/fs/nfsd/nfssvc.c
index 076f35dc17e4..6754cbc27c71 100644
--- a/fs/nfsd/nfssvc.c
+++ b/fs/nfsd/nfssvc.c
@@ -750,8 +750,18 @@ int nfsd_set_nrthreads(int n, int *nthreads, struct net *net)
 					  &nn->nfsd_serv->sv_pools[i],
 					  nthreads[i]);
 		if (err)
-			break;
+			goto out;
 	}
+
+	/* Anything undefined in array is considered to be 0 */
+	for (i = n; i < nn->nfsd_serv->sv_nrpools; ++i) {
+		err = svc_set_num_threads(nn->nfsd_serv,
+					  &nn->nfsd_serv->sv_pools[i],
+					  0);
+		if (err)
+			goto out;
+	}
+out:
 	return err;
 }

-- 
2.45.1