NFSD: Refactor transport removal out of __write_ports()

Clean up: Refactor transport removal out of __write_ports() to make it
easier to understand and maintain.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>

fs/nfsd/nfsctl.c

@@ -910,6 +910,31 @@ static ssize_t write_versions(struct file *file, char *buf, size_t size)
 	return rv;
 }
 
+/*
+ * A transport listener is removed by writing a "-", it's transport
+ * name, and it's port number.
+ */
+static ssize_t __write_ports_delxprt(char *buf)
+{
+	struct svc_xprt *xprt;
+	char transport[16];
+	int port;
+
+	if (sscanf(&buf[1], "%15s %4u", transport, &port) != 2)
+		return -EINVAL;
+
+	if (port < 1 || port > USHORT_MAX || nfsd_serv == NULL)
+		return -EINVAL;
+
+	xprt = svc_find_xprt(nfsd_serv, transport, AF_UNSPEC, port);
+	if (xprt == NULL)
+		return -ENOTCONN;
+
+	svc_close_xprt(xprt);
+	svc_xprt_put(xprt);
+	return 0;
+}
+
 static ssize_t __write_ports(struct file *file, char *buf, size_t size)
 {
 	if (size == 0) {
@@ -984,30 +1009,10 @@ static ssize_t __write_ports(struct file *file, char *buf, size_t size)
 			return err < 0 ? err : 0;
 		}
 	}
-	/*
-	 * Remove a transport by writing it's transport name and port number
-	 */
-	if (buf[0] == '-' && isalpha(buf[1])) {
-		struct svc_xprt *xprt;
-		int err = -EINVAL;
-		char transport[16];
-		int port;
-		if (sscanf(&buf[1], "%15s %4d", transport, &port) == 2) {
-			if (port < 1 || port > 65535)
-				return -EINVAL;
-			if (nfsd_serv) {
-				xprt = svc_find_xprt(nfsd_serv, transport,
-						     AF_UNSPEC, port);
-				if (xprt) {
-					svc_close_xprt(xprt);
-					svc_xprt_put(xprt);
-					err = 0;
-				} else
-					err = -ENOTCONN;
-			}
-			return err < 0 ? err : 0;
-		}
-	}
+
+	if (buf[0] == '-' && isalpha(buf[1]))
+		return __write_ports_delxprt(buf);
+
 	return -EINVAL;
 }