sockfd_lookup_light(): switch to fdget^W^Waway from fget_light

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

net/socket.c

@@ -450,16 +450,17 @@ EXPORT_SYMBOL(sockfd_lookup);
 
 static struct socket *sockfd_lookup_light(int fd, int *err, int *fput_needed)
 {
-	struct file *file;
+	struct fd f = fdget(fd);
 	struct socket *sock;
 
 	*err = -EBADF;
-	file = fget_light(fd, fput_needed);
-	if (file) {
-		sock = sock_from_file(file, err);
-		if (sock)
+	if (f.file) {
+		sock = sock_from_file(f.file, err);
+		if (likely(sock)) {
+			*fput_needed = f.flags;
 			return sock;
-		fput_light(file, *fput_needed);
+		}
+		fdput(f);
 	}
 	return NULL;
 }