NFSv4: Cache the NFSv4/v4.1 client owner_id in the struct nfs_client

Ensure that we cache the NFSv4/v4.1 client owner_id so that we can
verify it when we're doing trunking detection.
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>

fs/nfs/nfs4client.c

@@ -228,6 +228,7 @@ static void nfs4_shutdown_client(struct nfs_client *clp)
 	kfree(clp->cl_serverowner);
 	kfree(clp->cl_serverscope);
 	kfree(clp->cl_implid);
+	kfree(clp->cl_owner_id);
 }
 
 void nfs4_free_client(struct nfs_client *clp)

fs/nfs/nfs4proc.c

@@ -4917,11 +4917,14 @@ static void nfs4_init_boot_verifier(const struct nfs_client *clp,
 }
 
 static unsigned int
-nfs4_init_nonuniform_client_string(const struct nfs_client *clp,
+nfs4_init_nonuniform_client_string(struct nfs_client *clp,
 				   char *buf, size_t len)
 {
 	unsigned int result;
 
+	if (clp->cl_owner_id != NULL)
+		return strlcpy(buf, clp->cl_owner_id, len);
+
 	rcu_read_lock();
 	result = scnprintf(buf, len, "Linux NFSv4.0 %s/%s %s",
 				clp->cl_ipaddr,
@@ -4930,24 +4933,32 @@ nfs4_init_nonuniform_client_string(const struct nfs_client *clp,
 				rpc_peeraddr2str(clp->cl_rpcclient,
 							RPC_DISPLAY_PROTO));
 	rcu_read_unlock();
+	clp->cl_owner_id = kstrdup(buf, GFP_KERNEL);
 	return result;
 }
 
 static unsigned int
-nfs4_init_uniform_client_string(const struct nfs_client *clp,
+nfs4_init_uniform_client_string(struct nfs_client *clp,
 				char *buf, size_t len)
 {
 	const char *nodename = clp->cl_rpcclient->cl_nodename;
+	unsigned int result;
+
+	if (clp->cl_owner_id != NULL)
+		return strlcpy(buf, clp->cl_owner_id, len);
 
 	if (nfs4_client_id_uniquifier[0] != '\0')
-		return scnprintf(buf, len, "Linux NFSv%u.%u %s/%s",
+		result = scnprintf(buf, len, "Linux NFSv%u.%u %s/%s",
 				clp->rpc_ops->version,
 				clp->cl_minorversion,
 				nfs4_client_id_uniquifier,
 				nodename);
-	return scnprintf(buf, len, "Linux NFSv%u.%u %s",
+	else
+		result = scnprintf(buf, len, "Linux NFSv%u.%u %s",
 				clp->rpc_ops->version, clp->cl_minorversion,
 				nodename);
+	clp->cl_owner_id = kstrdup(buf, GFP_KERNEL);
+	return result;
 }
 
 /*

include/linux/nfs_fs_sb.h

@@ -74,6 +74,9 @@ struct nfs_client {
 	/* idmapper */
 	struct idmap *		cl_idmap;
 
+	/* Client owner identifier */
+	const char *		cl_owner_id;
+
 	/* Our own IP address, as a null-terminated string.
 	 * This is used to generate the mv0 callback address.
 	 */