lockd: optionally use hostnames for identifying peers

Index: build/fs/lockd/host.c
===================================================================
@@ -498,6 +498,11 @@ __nsm_find(const struct sockaddr_in *sin
 	list_for_each(pos, &nsm_handles) {
 		nsm = list_entry(pos, struct nsm_handle, sm_link);
 
+		if (hostname && nsm_use_hostnames) {
+			if (strlen(nsm->sm_name) != hostname_len
+			 || memcmp(nsm->sm_name, hostname, hostname_len))
+				continue;
+		} else
 		if (!nlm_cmp_addr(&nsm->sm_addr, sin))
 			continue;
 		atomic_inc(&nsm->sm_count);

Index: build/fs/lockd/mon.c
===================================================================
@@ -47,6 +47,7 @@ nsm_mon_unmon(struct nsm_handle *nsm, u3
 	}
 
 	memset(&args, 0, sizeof(args));
+	args.mon_name = nsm->sm_name;
 	args.addr = nsm->sm_addr.sin_addr.s_addr;
 	args.prog = NLM_PROGRAM;
 	args.vers = 3;

@@ -157,7 +158,7 @@ out_err:
 static u32 *
 xdr_encode_common(struct rpc_rqst *rqstp, u32 *p, struct nsm_args *argp)
 {
-	char	buffer[20];
+	char	buffer[20], *name;
 
 	/*
 	 * Use the dotted-quad IP address of the remote host as

@@ -165,8 +166,13 @@ xdr_encode_common(struct rpc_rqst *rqstp
 	 * hostname first for whatever remote hostname it receives,
 	 * so this works alright.
 	 */
-	sprintf(buffer, "%u.%u.%u.%u", NIPQUAD(argp->addr));
-	if (!(p = xdr_encode_string(p, buffer))
+	if (nsm_use_hostnames) {
+		name = argp->mon_name;
+	} else {
+		sprintf(buffer, "%u.%u.%u.%u", NIPQUAD(argp->addr));
+		name = buffer;
+	}
+	if (!(p = xdr_encode_string(p, name))
 	 || !(p = xdr_encode_string(p, system_utsname.nodename)))
 		return ERR_PTR(-EIO);
 	*p++ = htonl(argp->prog);

Index: build/fs/lockd/svc.c
===================================================================
@@ -60,6 +60,7 @@ static unsigned long		nlm_grace_period;
 static unsigned long		nlm_timeout = LOCKD_DFLT_TIMEO;
 static int			nlm_udpport, nlm_tcpport;
 int				nlm_max_hosts = 256;
+int				nsm_use_hostnames = 0;
 
 /*
  * Constants needed for the sysctl interface.

@@ -376,6 +377,14 @@ static ctl_table nlm_sysctls[] = {
 		.mode		= 0644,
 		.proc_handler	= &proc_dointvec,
 	},
+	{
+		.ctl_name	= CTL_UNNUMBERED,
+		.procname	= "nsm_use_hostnames",
+		.data		= &nsm_use_hostnames,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= &proc_dointvec,
+	},
 
 	{ .ctl_name = 0 }
 };

Index: build/include/linux/lockd/lockd.h
===================================================================
@@ -144,6 +144,7 @@ extern struct svc_procedure	nlmsvc_proce
 extern int			nlmsvc_grace_period;
 extern unsigned long		nlmsvc_timeout;
 extern int			nlm_max_hosts;
+extern int			nsm_use_hostnames;
 
 /*
  * Lockd client functions

Index: build/include/linux/lockd/sm_inter.h
===================================================================
@@ -28,6 +28,8 @@ struct nsm_args {
 	u32		prog;		/* RPC callback info */
 	u32		vers;
 	u32		proc;
+
+	char *		mon_name;
 };
 
 /*