[SERVER] Automatically connect a dnbd3 device for a relayed image

[SERVER] Automatically disconnect dnbd3 device if local cache copy is complete
[SERVER] Pre-allocate disk space for cache file
[KERNEL] Refuse connection if server reports disk size < 4096 bytes

2 files changed, 37 insertions, 24 deletions

diff --git a/src/kernel/blk.c b/src/kernel/blk.c
index 388f8b6..938a0e8 100644
--- a/src/kernel/blk.c
+++ b/src/kernel/blk.c
@@ -99,34 +99,39 @@ struct block_device_operations dnbd3_blk_ops =
 
 int dnbd3_blk_ioctl(struct block_device *bdev, fmode_t mode, unsigned int cmd, unsigned long arg)
 {
-	int result = 0;
+	int result = -100;
 	dnbd3_device_t *dev = bdev->bd_disk->private_data;
 	struct request_queue *blk_queue = dev->disk->queue;
 	char *imgname = NULL;
-	dnbd3_ioctl_t *msg = kmalloc(sizeof(*msg), GFP_KERNEL);
-	unsigned long irqflags;
+	dnbd3_ioctl_t *msg = NULL;
+	//unsigned long irqflags;
 
-	if (msg == NULL) return -ENOMEM;
-	copy_from_user((char *)msg, (char *)arg, 2);
-	if (msg->len != sizeof(*msg))
+	if (arg != 0)
 	{
-		result = -ENOEXEC;
-		goto cleanup_return;
-	}
-	copy_from_user((char *)msg, (char *)arg, sizeof(*msg));
-	if (msg->imgname != NULL && msg->imgnamelen > 0)
-	{
-		imgname = kmalloc(msg->imgnamelen + 1, GFP_KERNEL);
-		if (imgname == NULL)
+		msg = kmalloc(sizeof(*msg), GFP_KERNEL);
+		if (msg == NULL) return -ENOMEM;
+		copy_from_user((char *)msg, (char *)arg, 2);
+		if (msg->len != sizeof(*msg))
 		{
-			result = -ENOMEM;
+			result = -ENOEXEC;
 			goto cleanup_return;
 		}
-		copy_from_user(imgname, msg->imgname, msg->imgnamelen);
-		imgname[msg->imgnamelen] = '\0';
-		//printk("IOCTL Image name of len %d is %s\n", (int)msg->imgnamelen, imgname);
+		copy_from_user((char *)msg, (char *)arg, sizeof(*msg));
+		if (msg->imgname != NULL && msg->imgnamelen > 0)
+		{
+			imgname = kmalloc(msg->imgnamelen + 1, GFP_KERNEL);
+			if (imgname == NULL)
+			{
+				result = -ENOMEM;
+				goto cleanup_return;
+			}
+			copy_from_user(imgname, msg->imgname, msg->imgnamelen);
+			imgname[msg->imgnamelen] = '\0';
+			//printk("IOCTL Image name of len %d is %s\n", (int)msg->imgnamelen, imgname);
+		}
 	}
 
+
 	switch (cmd)
 	{
 	case IOCTL_OPEN:
@@ -196,7 +201,6 @@ int dnbd3_blk_ioctl(struct block_device *bdev, fmode_t mode, unsigned int cmd, u
 		}
 		else
 		{
-			spin_lock_irqsave(&dev->blk_lock, irqflags);
 			if (dev->new_servers_num >= NUMBER_SERVERS)
 				result = -EAGAIN;
 			else
@@ -206,11 +210,11 @@ int dnbd3_blk_ioctl(struct block_device *bdev, fmode_t mode, unsigned int cmd, u
 				++dev->new_servers_num;
 				result = 0;
 			}
-			spin_unlock_irqrestore(&dev->blk_lock, irqflags);
 		}
 		break;
 
 	case BLKFLSBUF:
+		result = 0;
 		break;
 
 	default:
diff --git a/src/kernel/net.c b/src/kernel/net.c
index 67a4b17..d6ebb32 100644
--- a/src/kernel/net.c
+++ b/src/kernel/net.c
@@ -231,6 +231,8 @@ int dnbd3_net_connect(dnbd3_device_t *dev)
 			error_dev_va("FATAL: Server provides rid %d, requested was %d.", (int)rid, (int)dev->rid);
 		dev->rid = rid;
 		dev->reported_size = serializer_get_uint64(&dev->payload_buffer);
+		if (dev->reported_size < 4096)
+			error_dev("ERROR: Reported size by server is < 4096");
 		// store image information
 		set_capacity(dev->disk, dev->reported_size >> 9); /* 512 Byte blocks */
 		debug_dev_va("INFO: Filesize: %llu.", dev->reported_size);
@@ -442,6 +444,9 @@ int dnbd3_net_discover(void *data)
 			continue;
 		dev->discover = 0;
 
+		if (dev->reported_size < 4096)
+			continue;
+
 		// Check if the list of alt servers needs to be updated and do so if neccessary
 		if (dev->new_servers_num)
 		{
@@ -457,6 +462,7 @@ int dnbd3_net_discover(void *data)
 					{
 						// REMOVE request
 						alt_server->host.type = 0;
+						debug_dev_va("Removing alt server %pI4", alt_server->host.addr);
 						continue;
 					}
 					// ADD, so just reset fail counter
@@ -469,9 +475,8 @@ int dnbd3_net_discover(void *data)
 				if (alt_server == NULL) // All NUMBER_SERVERS slots are taken, ignore entry
 					continue;
 				// Add new server entry
-				memcpy(alt_server->host.addr, dev->new_servers[i].host.addr, 16);
-				alt_server->host.type = dev->new_servers[i].host.type;
-				alt_server->host.port = dev->new_servers[i].host.port;
+				alt_server->host = dev->new_servers[i].host;
+				debug_dev_va("Adding alt server %pI4", alt_server->host.addr);
 				alt_server->rtts[0] = alt_server->rtts[1]
 				                      = alt_server->rtts[2] = alt_server->rtts[3]
 				                              = RTT_UNREACHABLE;
@@ -576,7 +581,11 @@ int dnbd3_net_discover(void *data)
 			// Request block
 			dnbd3_request.cmd = CMD_GET_BLOCK;
 			// Pick random block
-			if (sizeof(size_t) >= 8)
+			if (dev->reported_size == 0)
+			{
+				dnbd3_request.offset = 0;
+			}
+			else if (sizeof(size_t) >= 8)
 			{
 				dnbd3_request.offset = ((((start.tv_usec << 12) ^ start.tv_usec) << 4) % dev->reported_size) & ~(uint64_t)(RTT_BLOCK_SIZE-1);
 				//printk("Random offset 64bit: %lluMiB\n", (unsigned long long)(dnbd3_request.offset >> 20));