Test that timing out a write causes a disconnect and a reconnect

src/mirror.c

@@ -189,7 +189,8 @@ int mirror_pass(struct server * serve, int should_lock, uint64_t *written)
 						current,
 						run,
 						0,
-						serve->mirror->mapped + current);
+						serve->mirror->mapped + current,
+						MS_REQUEST_LIMIT_SECS);
 
 				/* now mark it clean */
 				bitset_clear_range(map, current, run);

src/mirror.h

@@ -10,12 +10,14 @@
 enum mirror_state;
 #include "serve.h"
 
+
 /* MS_CONNECT_TIME_SECS
  * The length of time after which the sender will assume a connect() to
  * the destination has failed.
  */
 #define MS_CONNECT_TIME_SECS 60
 
+
 /* MS_HELLO_TIME_SECS
  * The length of time the sender will wait for the NBD hello message
  * after connect() before aborting the connection attempt.
@@ -29,6 +31,16 @@ enum mirror_state;
  */
 #define MS_RETRY_DELAY_SECS 1
 
+
+/* MS_REQUEST_LIMIT_SECS
+ * We must receive a reply to a request within this time.  For a read
+ * request, this is the time between the end of the NBD request and the
+ * start of the NBD reply.  For a write request, this is the time
+ * between the end of the written data and the start of the NBD reply.
+ */
+#define MS_REQUEST_LIMIT_SECS 4
+
+
 enum mirror_finish_action {
 	ACTION_EXIT,
 	ACTION_NOTHING

src/readwrite.c

@@ -81,7 +81,24 @@ void read_reply(int fd, struct nbd_request *request, struct nbd_reply *reply)
 	}
 }
 
-void socket_nbd_read(int fd, off64_t from, int len, int out_fd, void* out_buf)
+void wait_for_data( int fd, int timeout_secs )
+{
+	fd_set fds;
+	struct timeval tv = {timeout_secs, 0};
+	int selected;
+
+	FD_ZERO( &fds );
+	FD_SET( fd, &fds );
+	selected = select( FD_SETSIZE, 
+			&fds, NULL, NULL, 
+			timeout_secs >=0 ? &tv : NULL );
+
+	FATAL_IF( -1 == selected, "Select failed" );
+	ERROR_IF(  0 == selected, "Timed out waiting for reply" );
+}
+
+
+void socket_nbd_read(int fd, off64_t from, int len, int out_fd, void* out_buf, int timeout_secs)
 {
 	struct nbd_request request;
 	struct nbd_reply   reply;
@@ -89,6 +106,8 @@ void socket_nbd_read(int fd, off64_t from, int len, int out_fd, void* out_buf)
 	fill_request(&request, REQUEST_READ, from, len);
 	FATAL_IF_NEGATIVE(writeloop(fd, &request, sizeof(request)),
 	  "Couldn't write request");
+
+	wait_for_data( fd, timeout_secs );
 	read_reply(fd, &request, &reply);
 	
 	if (out_buf) {
@@ -103,7 +122,7 @@ void socket_nbd_read(int fd, off64_t from, int len, int out_fd, void* out_buf)
 	}
 }
 
-void socket_nbd_write(int fd, off64_t from, int len, int in_fd, void* in_buf)
+void socket_nbd_write(int fd, off64_t from, int len, int in_fd, void* in_buf, int timeout_secs)
 {
 	struct nbd_request request;
 	struct nbd_reply   reply;
@@ -123,6 +142,7 @@ void socket_nbd_write(int fd, off64_t from, int len, int in_fd, void* in_buf)
 		);
 	}
 	
+	wait_for_data( fd, timeout_secs );
 	read_reply(fd, &request, &reply);
 }
 
@@ -175,7 +195,7 @@ void do_read(struct mode_readwrite_params* params)
 	FATAL_IF_NEGATIVE( params->client, "Couldn't connect." );
 	CHECK_RANGE("read");
 	socket_nbd_read(params->client, params->from, params->len, 
-	  params->data_fd, NULL);
+	  params->data_fd, NULL, 10);
 	close(params->client);
 }
 
@@ -185,7 +205,7 @@ void do_write(struct mode_readwrite_params* params)
 	FATAL_IF_NEGATIVE( params->client, "Couldn't connect." );
 	CHECK_RANGE("write");
 	socket_nbd_write(params->client, params->from, params->len, 
-	  params->data_fd, NULL);
+	  params->data_fd, NULL, 10);
 	close(params->client);
 }
 

src/readwrite.h

@@ -7,8 +7,8 @@
 
 int socket_connect(struct sockaddr* to, struct sockaddr* from);
 int socket_nbd_read_hello(int fd, off64_t * size);
-void socket_nbd_read(int fd, off64_t from, int len, int out_fd, void* out_buf);
-void socket_nbd_write(int fd, off64_t from, int len, int out_fd, void* out_buf);
+void socket_nbd_read(int fd, off64_t from, int len, int out_fd, void* out_buf, int timeout_secs);
+void socket_nbd_write(int fd, off64_t from, int len, int out_fd, void* out_buf, int timeout_secs);
 void socket_nbd_entrust(int fd);
 int socket_nbd_disconnect( int fd );
 

tests/fakes/dest/hang_after_write.rb

@@ -0,0 +1,27 @@
+#!/usr/bin/env ruby
+# encoding: utf-8
+
+# Open a socket, say hello, receive a write, then sleep for > 6
+# seconds. This should tell the source that the write has gone MIA,
+# and we expect a reconnect.
+
+require 'flexnbd/fake_dest'
+include FlexNBD::FakeDest
+
+sock = serve( *ARGV )
+client_sock1 = accept( sock )
+write_hello( client_sock1 )
+read_request( client_sock1 )
+
+t = Thread.start do
+  client_sock2 = accept( sock, "Timed out waiting for a reconnection",
+                        FlexNBD::MS_REQUEST_LIMIT_SECS + 1 )
+  client_sock2.close
+end
+
+sleep( FlexNBD::MS_REQUEST_LIMIT_SECS + 2 )
+client_sock1.close
+
+t.join
+
+exit(0)

tests/flexnbd/fake_dest.rb

@@ -13,7 +13,7 @@ module FlexNBD
     end
 
 
-    def accept( sock, err_msg, timeout=2 )
+    def accept( sock, err_msg = "Timed out waiting for a connection", timeout=2 )
       client_sock = nil
 
       begin
@@ -47,5 +47,11 @@ module FlexNBD
       client_sock.write( "\x00" * 128 )
     end
 
-  end
+
+    def read_request( client_sock )
+      client_sock.read(28)
+    end
+
+
+  end # module FakeDest
 end # module FlexNBD

tests/nbd_scenarios

@@ -274,6 +274,14 @@ class NBDConnectSourceFailureScenarios < Test::Unit::TestCase
   end
 
 
+  def test_write_times_out_causes_retry
+    @env.run_fake( "dest/hang_after_write", @env.ip, @env.port2 )
+    stdout, stderr = @env.mirror12_unchecked
+
+    assert @env.fake_reports_success, "Fake failed."
+  end
+
+
 end