svc: Add svc_xprt_names service to replace svc_sock_names

Create a transport independent version of the svc_sock_names function.

The toclose capability of the svc_sock_names service can be implemented
using the svc_xprt_find and svc_xprt_close services.

Signed-off-by: Tom Tucker <[e-mail]>
Acked-by: Neil Brown <[e-mail]>
Reviewed-by: Chuck Lever <[e-mail]>
Reviewed-by: Greg Banks <[e-mail]>
Signed-off-by: J. Bruce Fields <[e-mail]>

fs/nfsd/nfsctl.c

···
 		int len = 0;
 		lock_kernel();
 		if (nfsd_serv)
-			len = svc_sock_names(buf, nfsd_serv, NULL);
+			len = svc_xprt_names(nfsd_serv, buf, 0);
 		unlock_kernel();
 		return len;
 	}

include/linux/sunrpc/svc_xprt.h

···
 int	svc_port_is_privileged(struct sockaddr *sin);
 int	svc_print_xprts(char *buf, int maxlen);
 struct	svc_xprt *svc_find_xprt(struct svc_serv *, char *, int, int);
+int	svc_xprt_names(struct svc_serv *serv, char *buf, int buflen);
 
 static inline void svc_xprt_get(struct svc_xprt *xprt)
 {

net/sunrpc/svc_xprt.c

···
 	return found;
 }
 EXPORT_SYMBOL_GPL(svc_find_xprt);
+
+/*
+ * Format a buffer with a list of the active transports. A zero for
+ * the buflen parameter disables target buffer overflow checking.
+ */
+int svc_xprt_names(struct svc_serv *serv, char *buf, int buflen)
+{
+	struct svc_xprt *xprt;
+	char xprt_str[64];
+	int totlen = 0;
+	int len;
+
+	/* Sanity check args */
+	if (!serv)
+		return 0;
+
+	spin_lock_bh(&serv->sv_lock);
+	list_for_each_entry(xprt, &serv->sv_permsocks, xpt_list) {
+		len = snprintf(xprt_str, sizeof(xprt_str),
+			       "%s %d\n", xprt->xpt_class->xcl_name,
+			       svc_xprt_local_port(xprt));
+		/* If the string was truncated, replace with error string */
+		if (len >= sizeof(xprt_str))
+			strcpy(xprt_str, "name-too-long\n");
+		/* Don't overflow buffer */
+		len = strlen(xprt_str);
+		if (buflen && (len + totlen >= buflen))
+			break;
+		strcpy(buf+totlen, xprt_str);
+		totlen += len;
+	}
+	spin_unlock_bh(&serv->sv_lock);
+	return totlen;
+}
+EXPORT_SYMBOL_GPL(svc_xprt_names);