[KERNEL/CLIENT] Several minor tweaks and changes

- Disable panic timeout that reports errors to block layer by default
- Get rid of "is_server" used by old proxy mode, introduce
  "honor_server_alts" that just controls whether we use alts provided by
  the server
- Allow switching servers when we only have 3 RTT measurements
- If using alts provided by server, don't ignore those that come from
  other servers than the initial one

3 files changed, 13 insertions, 13 deletions

diff --git a/src/kernel/blk.c b/src/kernel/blk.c
index e55de25..3e3cdd7 100644
--- a/src/kernel/blk.c
+++ b/src/kernel/blk.c
@@ -169,7 +169,7 @@ int dnbd3_blk_ioctl(struct block_device *bdev, fmode_t mode, unsigned int cmd, u
 			memcpy(&dev->initial_server, &dev->cur_server, sizeof(dev->initial_server));
 			dev->imgname = imgname;
 			dev->rid = msg->rid;
-			dev->is_server = msg->is_server;
+			dev->use_server_provided_alts = msg->use_server_provided_alts;
 			// Forget all alt servers on explicit connect, set first al server to initial server
 			memset(dev->alt_servers, 0, sizeof(dev->alt_servers[0])*NUMBER_SERVERS);
 			memcpy(dev->alt_servers, &dev->initial_server, sizeof(dev->alt_servers[0]));
@@ -266,7 +266,7 @@ void dnbd3_blk_request(struct request_queue *q)
 			continue;
 		}
 
-		if (dev->panic_count >= PROBE_COUNT_TIMEOUT)
+		if (PROBE_COUNT_TIMEOUT > 0 && dev->panic_count >= PROBE_COUNT_TIMEOUT)
 		{
 			__blk_end_request_all(req, -EIO);
 			continue;
diff --git a/src/kernel/dnbd3.h b/src/kernel/dnbd3.h
index c0c7f4d..f8af69f 100644
--- a/src/kernel/dnbd3.h
+++ b/src/kernel/dnbd3.h
@@ -60,7 +60,8 @@ typedef struct
 	dnbd3_server_t alt_servers[NUMBER_SERVERS]; // array of alt servers
 	int new_servers_num;	// number of new alt servers that are waiting to be copied to above array
 	dnbd3_server_entry_t new_servers[NUMBER_SERVERS]; // pending new alt servers
-	uint8_t discover, panic, disconnecting, is_server, update_available, panic_count;
+	uint8_t discover, panic, disconnecting, update_available, panic_count;
+	uint8_t use_server_provided_alts;
 	uint16_t rid;
 	uint32_t heartbeat_count;
 	uint64_t reported_size;
diff --git a/src/kernel/net.c b/src/kernel/net.c
index 3392feb..58b4664 100644
--- a/src/kernel/net.c
+++ b/src/kernel/net.c
@@ -210,7 +210,7 @@ int dnbd3_net_connect(dnbd3_device_t *dev)
 		serializer_put_uint16(&dev->payload_buffer, PROTOCOL_VERSION);
 		serializer_put_string(&dev->payload_buffer, dev->imgname);
 		serializer_put_uint16(&dev->payload_buffer, dev->rid);
-		serializer_put_uint8(&dev->payload_buffer, dev->is_server);
+		serializer_put_uint8(&dev->payload_buffer, 0); // is_server = false
 		iov[1].iov_base = &dev->payload_buffer;
 		dnbd3_request.size = iov[1].iov_len = serializer_get_written_length(&dev->payload_buffer);
 		fixup_request(dnbd3_request);
@@ -731,7 +731,7 @@ int dnbd3_net_discover(void *data)
 		if (dev->panic)
 		{
 			// After 21 retries, bail out by reporting errors to block layer
-			if (dev->panic_count < 255 && ++dev->panic_count == PROBE_COUNT_TIMEOUT + 1)
+			if (PROBE_COUNT_TIMEOUT > 0 && dev->panic_count < 255 && ++dev->panic_count == PROBE_COUNT_TIMEOUT + 1)
 				dnbd3_blk_fail_all_requests(dev);
 		}
 
@@ -745,7 +745,7 @@ int dnbd3_net_discover(void *data)
 			continue;
 		}
 
-		do_change = !dev->is_server && ready && best_server != current_server && (start.tv_usec & 3) != 0
+		do_change = ready && best_server != current_server && (start.tv_usec & 3) != 0
 				   && RTT_THRESHOLD_FACTOR(dev->cur_rtt) > best_rtt + 1500;
 
 		if (ready && !do_change) {
@@ -765,7 +765,7 @@ int dnbd3_net_discover(void *data)
 			spin_unlock_irqrestore(&dev->blk_lock, irqflags);
 		}
 
-		// take server with lowest rtt (only if in client mode)
+		// take server with lowest rtt
 		if (do_change)
 		{
 			printk("INFO: Server %d on %s is faster (%lluµs vs. %lluµs)\n", best_server, dev->disk->disk_name,
@@ -787,9 +787,9 @@ int dnbd3_net_discover(void *data)
 			best_sock = NULL;
 		}
 
-		if (!ready || (start.tv_usec & 7) != 0)
+		if (!ready || (start.tv_usec & 15) != 0)
 			turn = (turn + 1) % 4;
-		if (turn == 3)
+		if (turn == 2) // Set ready when we only have 2 of 4 measurements for quicker load balancing
 			ready = 1;
 
 	}
@@ -1002,11 +1002,10 @@ int dnbd3_net_receive(void *data)
 			continue;
 
 		case CMD_GET_SERVERS:
-			if (dev->is_server || !is_same_server(&dev->cur_server, &dev->initial_server))
+			if (!dev->use_server_provided_alts)
 			{
-				// If not connected to initial server, or device is in proxy mode, ignore this message
 				remaining = dnbd3_reply.size;
-				goto clear_remaining_payload;
+				goto consume_payload;
 			}
 			spin_lock_irqsave(&dev->blk_lock, irqflags);
 			dev->new_servers_num = 0;
@@ -1026,7 +1025,7 @@ int dnbd3_net_receive(void *data)
 			}
 			// If there were more servers than accepted, remove the remaining data from the socket buffer
 			remaining = dnbd3_reply.size - (count * sizeof(dnbd3_server_entry_t));
-			clear_remaining_payload: while (remaining > 0)
+			consume_payload: while (remaining > 0)
 			{
 				count = MIN(sizeof(dnbd3_reply), remaining); // Abuse the reply struct as the receive buffer
 				iov.iov_base = &dnbd3_reply;