listen: Turn off CLIENT_MAX_WAIT_SECS

The idea behind this feature was to avoid the client thread in a listen
server getting stuck forever if the mirroring thread in the source died.
However, it breaks any sane implementation of max_Bps in that thread,
and there are lingering concerns over how it might operate under normal
conditions anyway.

Specifically, if iterating over the bitmap takes a long time, or even just
reading the requisite 8MB from the disc in order to send it, then the
5-second timeout could be hit, causing mirroring to fail unnecessarily.

src/client.c

@@ -192,14 +192,19 @@ int client_read_request( struct client * client , struct nbd_request *out_reques
 
 	struct nbd_request_raw request_raw;
 	fd_set                 fds;
-	struct timeval         tv = {CLIENT_MAX_WAIT_SECS, 0};
-	struct timeval *       ptv;
+	struct timeval *       ptv = NULL;
 	int                    fd_count;
 
-	/* We want a timeout if this is an inbound migration, but not
-	 * otherwise
+	/* We want a timeout if this is an inbound migration, but not otherwise.
+	 * This is compile-time selectable, as it will break mirror max_bps
 	 */
-	ptv = server_is_in_control( client->serve ) ? NULL : &tv;
+#ifdef HAS_LISTEN_TIMEOUT
+	struct timeval         tv = {CLIENT_MAX_WAIT_SECS, 0};
+
+	if ( !server_is_in_control( client->serve ) ) {
+		ptv = &tv;
+	}
+#endif
 
 	FD_ZERO(&fds);
 	FD_SET(client->socket, &fds);

src/client.h

@@ -4,6 +4,8 @@
 #include <signal.h>
 #include <time.h>
 
+#ifdef HAS_LISTEN_TIMEOUT
+
 /** CLIENT_MAX_WAIT_SECS
  * This is the length of time an inbound migration will wait for a fresh
  * write before assuming the source has Gone Away.  Note: it is *not*
@@ -12,6 +14,8 @@
  */
 #define CLIENT_MAX_WAIT_SECS 5
 
+#endif
+
 /** CLIENT_HANDLER_TIMEOUT
  * This is the length of time (in seconds) any request can be outstanding for.
  * If we spend longer than this in a request, the whole server is killed.

tests/acceptance/test_dest_error_handling.rb

@@ -21,12 +21,13 @@ class TestDestErrorHandling  < Test::Unit::TestCase
     assert_no_control
   end
 
-
+=begin
+  # This is disabled while CLIENT_MAX_WAIT_SECS is removed
   def test_hello_goes_astray_causes_timeout_error
     run_fake( "source/hang_after_hello" )
     assert_no_control
   end
-
+=end
 
   def test_sigterm_has_bad_exit_status
     @env.nbd1.can_die(1)
@@ -99,3 +100,4 @@ class TestDestErrorHandling  < Test::Unit::TestCase
   end
 
 end # class TestDestErrorHandling
+