NFSD: convert callback RPC program to per-net namespace

The callback channel's rpc_program, rpc_version, rpc_stat,
and per-procedure counts are declared as file-scope statics in
nfs4callback.c, shared across all network namespaces.
Forechannel RPC statistics are already maintained per-netns
(via nfsd_svcstats in struct nfsd_net); the backchannel
has no such separation. When backchannel statistics are
eventually surfaced to userspace, the global counters would
expose cross-namespace data.

Allocate per-netns copies of these structures through a new
opaque struct nfsd_net_cb, managed by nfsd_net_cb_init()
and nfsd_net_cb_shutdown(). The struct definition is private
to nfs4callback.c; struct nfsd_net holds only a pointer.

Signed-off-by: Dai Ngo <dai.ngo@oracle.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

Author: daimngo

fs/nfsd/netns.h

@@ -25,6 +25,7 @@
 #define SESSION_HASH_SIZE	512
 
 struct cld_net;
+struct nfsd_net_cb;
 struct nfsd4_client_tracking_ops;
 
 enum {
@@ -228,6 +229,8 @@ struct nfsd_net {
 	struct list_head	local_clients;
 #endif
 	siphash_key_t		*fh_key;
+
+	struct nfsd_net_cb	*nfsd_cb;
 };
 
 /* Simple check to find out if a given net was properly initialized */

fs/nfsd/nfs4callback.c

@@ -1032,39 +1032,14 @@ static const struct rpc_procinfo nfs4_cb_procedures[] = {
 	PROC(CB_GETATTR,	COMPOUND,	cb_getattr,	cb_getattr),
 };
 
-static unsigned int nfs4_cb_counts[ARRAY_SIZE(nfs4_cb_procedures)];
-static const struct rpc_version nfs_cb_version4 = {
-/*
- * Note on the callback rpc program version number: despite language in rfc
- * 5661 section 18.36.3 requiring servers to use 4 in this field, the
- * official xdr descriptions for both 4.0 and 4.1 specify version 1, and
- * in practice that appears to be what implementations use.  The section
- * 18.36.3 language is expected to be fixed in an erratum.
- */
-	.number			= 1,
-	.nrprocs		= ARRAY_SIZE(nfs4_cb_procedures),
-	.procs			= nfs4_cb_procedures,
-	.counts			= nfs4_cb_counts,
-};
-
-static const struct rpc_version *nfs_cb_version[2] = {
-	[1] = &nfs_cb_version4,
-};
-
-static const struct rpc_program cb_program;
-
-static struct rpc_stat cb_stats = {
-	.program		= &cb_program
-};
-
-#define NFS4_CALLBACK 0x40000000
-static const struct rpc_program cb_program = {
-	.name			= "nfs4_cb",
-	.number			= NFS4_CALLBACK,
-	.nrvers			= ARRAY_SIZE(nfs_cb_version),
-	.version		= nfs_cb_version,
-	.stats			= &cb_stats,
-	.pipe_dir_name		= "nfsd4_cb",
+#define NFS4_CB_PROGRAM	0x40000000
+#define NFS4_CB_VERSION	1
+
+struct nfsd_net_cb {
+	struct rpc_version	version4;
+	const struct rpc_version *versions[NFS4_CB_VERSION + 1];
+	struct rpc_program	program;
+	struct rpc_stat		stat;
 };
 
 static int max_cb_time(struct net *net)
@@ -1140,6 +1115,7 @@ static const struct cred *get_backchannel_cred(struct nfs4_client *clp, struct r
 
 static int setup_callback_client(struct nfs4_client *clp, struct nfs4_cb_conn *conn, struct nfsd4_session *ses)
 {
+	struct nfsd_net *nn = net_generic(clp->net, nfsd_net_id);
 	int maxtime = max_cb_time(clp->net);
 	struct rpc_timeout	timeparms = {
 		.to_initval	= maxtime,
@@ -1152,14 +1128,14 @@ static int setup_callback_client(struct nfs4_client *clp, struct nfs4_cb_conn *c
 		.addrsize	= conn->cb_addrlen,
 		.saddress	= (struct sockaddr *) &conn->cb_saddr,
 		.timeout	= &timeparms,
-		.program	= &cb_program,
-		.version	= 1,
+		.version	= NFS4_CB_VERSION,
 		.flags		= (RPC_CLNT_CREATE_NOPING | RPC_CLNT_CREATE_QUIET),
 		.cred		= current_cred(),
 	};
 	struct rpc_clnt *client;
 	const struct cred *cred;
 
+	args.program = &nn->nfsd_cb->program;
 	if (clp->cl_minorversion == 0) {
 		if (!clp->cl_cred.cr_principal &&
 		    (clp->cl_cred.cr_flavor >= RPC_AUTH_GSS_KRB5)) {
@@ -1786,3 +1762,70 @@ bool nfsd4_run_cb(struct nfsd4_callback *cb)
 		nfsd41_cb_inflight_end(clp);
 	return queued;
 }
+
+/**
+ * nfsd_net_cb_shutdown - release per-netns callback RPC program resources
+ * @nn: NFS server network namespace
+ *
+ * Frees resources allocated by nfsd_net_cb_init().
+ */
+void nfsd_net_cb_shutdown(struct nfsd_net *nn)
+{
+	struct nfsd_net_cb *cb = nn->nfsd_cb;
+
+	if (cb) {
+		kfree(cb->version4.counts);
+		kfree(cb);
+		nn->nfsd_cb = NULL;
+	}
+}
+
+/**
+ * nfsd_net_cb_init - initialize per-netns callback RPC program
+ * @nn: NFS server network namespace
+ *
+ * Sets up the callback RPC program, version table, procedure
+ * counts, and statistics structure for @nn. Caller must release
+ * these resources using nfsd_net_cb_shutdown().
+ *
+ * Return: 0 on success, or -ENOMEM if allocation fails.
+ */
+int nfsd_net_cb_init(struct nfsd_net *nn)
+{
+	struct nfsd_net_cb *cb;
+
+	cb = kzalloc(sizeof(*cb), GFP_KERNEL);
+	if (!cb)
+		return -ENOMEM;
+
+	cb->version4.counts = kzalloc_objs(unsigned int,
+			ARRAY_SIZE(nfs4_cb_procedures), GFP_KERNEL);
+	if (!cb->version4.counts) {
+		kfree(cb);
+		return -ENOMEM;
+	}
+	/*
+	 * Note on the callback rpc program version number: despite language
+	 * in rfc 5661 section 18.36.3 requiring servers to use 4 in this
+	 * field, the official xdr descriptions for both 4.0 and 4.1 specify
+	 * version 1, and in practice that appears to be what implementations
+	 * use. The section 18.36.3 language is expected to be fixed in an
+	 * erratum.
+	 */
+	cb->version4.number = NFS4_CB_VERSION;
+	cb->version4.nrprocs = ARRAY_SIZE(nfs4_cb_procedures);
+	cb->version4.procs = nfs4_cb_procedures;
+	cb->versions[NFS4_CB_VERSION] = &cb->version4;
+
+	cb->program.name = "nfs4_cb";
+	cb->program.number = NFS4_CB_PROGRAM;
+	cb->program.nrvers = ARRAY_SIZE(cb->versions);
+	cb->program.version = &cb->versions[0];
+	cb->program.pipe_dir_name = "nfsd4_cb";
+	cb->program.stats = &cb->stat;
+	cb->stat.program = &cb->program;
+
+	nn->nfsd_cb = cb;
+
+	return 0;
+}

fs/nfsd/nfsctl.c

@@ -2203,6 +2203,9 @@ static __net_init int nfsd_net_init(struct net *net)
 	int retval;
 	int i;
 
+	retval = nfsd_net_cb_init(nn);
+	if (retval)
+		return retval;
 	retval = nfsd_export_init(net);
 	if (retval)
 		goto out_export_error;
@@ -2243,6 +2246,7 @@ static __net_init int nfsd_net_init(struct net *net)
 out_idmap_error:
 	nfsd_export_shutdown(net);
 out_export_error:
+	nfsd_net_cb_shutdown(nn);
 	return retval;
 }
 
@@ -2273,6 +2277,7 @@ static __net_exit void nfsd_net_exit(struct net *net)
 	struct nfsd_net *nn = net_generic(net, nfsd_net_id);
 
 	kfree_sensitive(nn->fh_key);
+	nfsd_net_cb_shutdown(nn);
 	nfsd_proc_stat_shutdown(net);
 	percpu_counter_destroy_many(nn->counter, NFSD_STATS_COUNTERS_NUM);
 	nfsd_idmap_shutdown(net);

fs/nfsd/state.h

@@ -862,13 +862,22 @@ struct nfsd_file *find_any_file(struct nfs4_file *f);
 #ifdef CONFIG_NFSD_V4
 void nfsd4_revoke_states(struct nfsd_net *nn, struct super_block *sb);
 void nfsd4_cancel_copy_by_sb(struct net *net, struct super_block *sb);
+int nfsd_net_cb_init(struct nfsd_net *nn);
+void nfsd_net_cb_shutdown(struct nfsd_net *nn);
 #else
 static inline void nfsd4_revoke_states(struct nfsd_net *nn, struct super_block *sb)
 {
 }
 static inline void nfsd4_cancel_copy_by_sb(struct net *net, struct super_block *sb)
 {
 }
+static inline int nfsd_net_cb_init(struct nfsd_net *nn)
+{
+	return 0;
+}
+static inline void nfsd_net_cb_shutdown(struct nfsd_net *nn)
+{
+}
 #endif
 
 /* grace period management */