added documentation

1 files changed, 131 insertions, 50 deletions

diff --git a/src/kernel/core.c b/src/kernel/core.c
index b945a55..cc19b58 100644
--- a/src/kernel/core.c
+++ b/src/kernel/core.c
@@ -52,7 +52,6 @@
 #include "clientconfig.h"
 #include "net.h"
 
-#define DNBD3_CMD_REQUEUED 1
 
 
 struct workqueue_struct *dnbd3_wq;
@@ -63,7 +62,10 @@ static unsigned int max_devs = NUMBER_DEVICES;
 static struct dnbd3_device *device;
 int major;
 
-
+/**
+ * dnbd3_requeue_cmd - requeue a command once
+ * @cmd: the command to requeue
+ */
 static void dnbd3_requeue_cmd(struct dnbd3_cmd *cmd)
 {
 	struct request *req = blk_mq_rq_from_pdu(cmd);
@@ -73,23 +75,25 @@ static void dnbd3_requeue_cmd(struct dnbd3_cmd *cmd)
 	}
 }
 
+/**
+ * dnbd3_handle_cmd - handles a mq command
+ * @cmd: the cmd to send
+ * @index: the index of the queue
+ */
 static int dnbd3_handle_cmd(struct dnbd3_cmd *cmd, int index)
 {
 	struct request *req = blk_mq_rq_from_pdu(cmd);
 	struct dnbd3_device *dev = cmd->dnbd3;
 	struct dnbd3_sock *sock = NULL;
+	bool first_try = true;
 	int ret = -1;
 	int i;
 	int sock_alive = 0;
 
-	debug_dev(dev, "handle request at position %lu, size %d, index %d", blk_rq_pos(req), blk_rq_bytes(req), index);
+	debug_dev(dev, "handle request at position %lu, size %d, index %d",
+			blk_rq_pos(req), blk_rq_bytes(req), index);
 
-//	if (index >= 1) { // TODO use next server with good rtt for this request
-//		printk(KERN_INFO "dnbd3: index is %d", index);
-//		dev_err_ratelimited(disk_to_dev(dev->disk), "attempted send on invalid socket\n");
-//		blk_mq_start_request(req);
-//		return -EINVAL;
-//	}
+again:
 
 	for (i = 0; i < NUMBER_CONNECTIONS; i++) {
 		if (dnbd3_is_sock_alive(dev->socks[i])) {
@@ -109,6 +113,13 @@ static int dnbd3_handle_cmd(struct dnbd3_cmd *cmd, int index)
 			ret = 0;
 			goto out;
 		}
+		if (first_try) {
+			debug_dev(dev, "no socket found, going to sleep");
+			msleep(SOCKET_TIMEOUT_CLIENT_DATA * 1000);
+			first_try = false;
+			goto again;
+		}
+		error_dev(dev, "failed to find a socket, end request");
 		blk_mq_end_request(req, BLK_STS_IOERR);
 		return -EINVAL;
 	}
@@ -141,7 +152,13 @@ out:
 	return ret;
 }
 
-static blk_status_t dnbd3_queue_rq(struct blk_mq_hw_ctx *hctx, const struct blk_mq_queue_data *bd)
+/**
+ * dnbd3_queue_rq - queue request
+ * @hctx: state for a hardware queue facing the hardware block device
+ * @bd: the queue data including the request
+ */
+static blk_status_t dnbd3_queue_rq(struct blk_mq_hw_ctx *hctx,
+		const struct blk_mq_queue_data *bd)
 {
 	struct dnbd3_cmd *cmd = blk_mq_rq_to_pdu(bd->rq);
 	int ret;
@@ -160,7 +177,15 @@ static blk_status_t dnbd3_queue_rq(struct blk_mq_hw_ctx *hctx, const struct blk_
 	return ret;
 }
 
-static int dnbd3_init_request(struct blk_mq_tag_set *set, struct request *rq, unsigned int hctx_idx, unsigned int numa_node)
+/**
+ * dnbd3_init_request - init a mq request
+ * @set: the mq tag set
+ * @rq: the request
+ * @hctx_idx:
+ * @numa_node:
+ */
+static int dnbd3_init_request(struct blk_mq_tag_set *set, struct request *rq,
+		unsigned int hctx_idx, unsigned int numa_node)
 {
 	struct dnbd3_cmd *cmd = blk_mq_rq_to_pdu(rq);
 	cmd->dnbd3 = set->driver_data;
@@ -168,7 +193,14 @@ static int dnbd3_init_request(struct blk_mq_tag_set *set, struct request *rq, un
 	mutex_init(&cmd->lock);
 	return 0;
 }
-static enum blk_eh_timer_return dnbd3_xmit_timeout(struct request *req, bool reserved)
+
+/**
+ * dnbd3_xmit_timeout - timeout function for mq
+ * @req: the timedout request
+ * @reserved:
+ */
+static enum blk_eh_timer_return dnbd3_xmit_timeout(struct request *req,
+		bool reserved)
 {
 	struct dnbd3_cmd *cmd = blk_mq_rq_to_pdu(req);
 	struct dnbd3_device *dev = cmd->dnbd3;
@@ -194,7 +226,10 @@ static enum blk_eh_timer_return dnbd3_xmit_timeout(struct request *req, bool res
 	return BLK_EH_DONE;
 }
 
-
+/**
+ * struct blk_mq_ops - dnbd3_mq_ops
+ * multiqueue operations
+ */
 static struct blk_mq_ops dnbd3_mq_ops = {
 	.queue_rq = dnbd3_queue_rq,
 	.init_request = dnbd3_init_request,
@@ -203,8 +238,15 @@ static struct blk_mq_ops dnbd3_mq_ops = {
 
 
 
-
-static int dnbd3_ioctl(struct block_device *bdev, fmode_t mode, unsigned int cmd, unsigned long arg)
+/**
+ * dnbd3_ioctl - the ioctl function of the dnbd3 kernel modul
+ * @bdev: the block device
+ * @mode:
+ * @cmd: the ioctl command
+ * @arg: the user data
+ */
+static int dnbd3_ioctl(struct block_device *bdev, fmode_t mode,
+		unsigned int cmd, unsigned long arg)
 {
 	int result = -EIO;
 	struct dnbd3_device *dev = bdev->bd_disk->private_data;
@@ -216,28 +258,35 @@ static int dnbd3_ioctl(struct block_device *bdev, fmode_t mode, unsigned int cmd
 
 	if (arg != 0) {
 		msg = kmalloc(sizeof(*msg), GFP_KERNEL);
-		if (msg == NULL) return -ENOMEM;
-		if (copy_from_user((char *)msg, (char *)arg, 2) != 0 || msg->len != sizeof(*msg)) {
+		if (msg == NULL) {
+			return -ENOMEM;
+		}
+		result = copy_from_user((char *)msg, (char *)arg, 2);
+		if (result != 0	|| msg->len != sizeof(*msg)) {
 			result = -ENOEXEC;
-			goto cleanup_return;
+			goto error;
 		}
-		if (copy_from_user((char *)msg, (char *)arg, sizeof(*msg)) != 0) {
+		result = copy_from_user((char *)msg, (char *)arg, sizeof(*msg));
+		if (result != 0) {
 			result = -ENOENT;
-			goto cleanup_return;
+			goto error;
 		}
 		if (msg->imgname != NULL && msg->imgnamelen > 0) {
 			imgname = kmalloc(msg->imgnamelen + 1, GFP_KERNEL);
 			if (imgname == NULL) {
 				result = -ENOMEM;
-				goto cleanup_return;
+				goto error;
 			}
-			if (copy_from_user(imgname, msg->imgname, msg->imgnamelen) != 0) {
+			result = copy_from_user(
+					imgname, msg->imgname, msg->imgnamelen);
+			if (result != 0) {
 				result = -ENOENT;
-				goto cleanup_return;
+				goto error;
 			}
 			imgname[msg->imgnamelen] = '\0';
 
-			debug_dev(dev, "ioctl image name of len %i is %s", (int)msg->imgnamelen, imgname);
+			debug_dev(dev, "ioctl image name of len %i is %s",
+					(int)msg->imgnamelen, imgname);
 		}
 	}
 
@@ -255,16 +304,22 @@ static int dnbd3_ioctl(struct block_device *bdev, fmode_t mode, unsigned int cmd
 			if (sizeof(msg->host) != sizeof(dev->initial_server.host)) {
 				warn_dev(dev, "odd size bug#1 triggered in ioctl");
 			}
-			memcpy(&dev->initial_server.host, &msg->host, sizeof(msg->host));
+			memcpy(&dev->initial_server.host, &msg->host,
+					sizeof(msg->host));
 			dev->initial_server.failures = 0;
-			dev->initial_server.rtts[0] = dev->initial_server.rtts[1] = dev->initial_server.rtts[2] = dev->initial_server.rtts[3] = RTT_UNREACHABLE;
-//			memcpy(&dev->initial_server, &dev->cur_server, sizeof(dev->initial_server));
+			dnbd3_set_rtt_unreachable(&dev->initial_server)
 			dev->imgname = imgname;
 			dev->rid = msg->rid;
-			dev->use_server_provided_alts = msg->use_server_provided_alts;
-			// Forget all alt servers on explicit connect, set first alt 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]));
+			dev->use_server_provided_alts =
+					msg->use_server_provided_alts;
+			/*
+			 * forget all alt servers on explicit connect, set first
+			 * alt 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]));
 			result = dnbd3_net_connect(dev);
 			imgname = NULL;
 		}
@@ -297,8 +352,11 @@ static int dnbd3_ioctl(struct block_device *bdev, fmode_t mode, unsigned int cmd
 		} else if (msg == NULL) {
 			result = -EINVAL;
 		} else {
-			memcpy(&dev->new_servers[dev->new_servers_num].host, &msg->host, sizeof(msg->host));
-			dev->new_servers[dev->new_servers_num].failures = (cmd == IOCTL_ADD_SRV ? 0 : 1); // 0 = ADD, 1 = REM
+			memcpy(&dev->new_servers[dev->new_servers_num].host,
+					&msg->host, sizeof(msg->host));
+			/* 0 = ADD, 1 = REM */
+			dev->new_servers[dev->new_servers_num].failures =
+					(cmd == IOCTL_ADD_SRV ? 0 : 1);
 			++dev->new_servers_num;
 			result = 0;
 		}
@@ -315,7 +373,7 @@ static int dnbd3_ioctl(struct block_device *bdev, fmode_t mode, unsigned int cmd
 		break;
 	}
 	mutex_unlock(&dev->device_lock);
-cleanup_return:
+error:
 	if (msg) kfree(msg);
 	if (imgname) kfree(imgname);
 	return result;
@@ -323,7 +381,10 @@ cleanup_return:
 }
 
 
-
+/**
+ * struct block_device_operations - dnbd3_fops
+ * device operations for ioctl
+ */
 static struct block_device_operations dnbd3_fops =
 {
 	.owner = THIS_MODULE,
@@ -334,7 +395,11 @@ static struct block_device_operations dnbd3_fops =
 
 
 
-
+/**
+ * dnbd3_add_device - add a dnbd3 device
+ * @dev: the device
+ * @minor: the minor number of the device
+ */
 int dnbd3_add_device(struct dnbd3_device *dev, int minor)
 {
 	struct gendisk *disk;
@@ -369,7 +434,8 @@ int dnbd3_add_device(struct dnbd3_device *dev, int minor)
 	dev->minor = minor;
 	dev->disk = disk;
 	dev->tag_set.ops = &dnbd3_mq_ops;
-	dev->tag_set.nr_hw_queues = 1; // this can be changed later with blk_mq_update_nr_hw_queues()
+	/* this can be changed later with blk_mq_update_nr_hw_queues() */
+	dev->tag_set.nr_hw_queues = 1;
 	dev->tag_set.queue_depth = 128;
 	dev->tag_set.numa_node = NUMA_NO_NODE;
 	dev->tag_set.cmd_size = sizeof(struct dnbd3_cmd);
@@ -428,13 +494,22 @@ out_free_dnbd3:
 
 
 
-
+/**
+ * dnbd3_init - init the dnbd3 kernel modul
+ */
 static int __init dnbd3_init(void)
 {
 	int i;
 	debug("starting kernel module");
 
-	dnbd3_wq = alloc_workqueue("kdnbd3", WQ_MEM_RECLAIM | WQ_FREEZABLE | WQ_UNBOUND, 0);
+	/*
+	 * allocate a workqueue/thread for this modul
+	 * WQ_MEM_RECLAIM - it is allowed to allocate memory
+	 * WQ_FREEZABLE - can go to sleep
+	 * WQ_UNBOUND - not bound to a certain CPU
+	 */
+	dnbd3_wq = alloc_workqueue("kdnbd3",
+			WQ_MEM_RECLAIM | WQ_FREEZABLE | WQ_UNBOUND, 0);
 
 	if (max_devs < 0) {
 		error("max_devs must be >= 0");
@@ -469,7 +544,12 @@ static int __init dnbd3_init(void)
 	return 0;
 }
 
-
+/**
+ * dnbd3_exit_cb - callback function for idr_for_each
+ * @id: the id
+ * @ptr: the entry
+ * @data: the callback data
+ */
 static int dnbd3_exit_cb(int id, void *ptr, void *data)
 {
 	struct list_head *list = (struct list_head *)data;
@@ -479,6 +559,10 @@ static int dnbd3_exit_cb(int id, void *ptr, void *data)
 	return 0;
 }
 
+/**
+ * dnbd3_dev_remove - remove the dnbd3 device
+ * @dev: the device to remove
+ */
 static void dnbd3_dev_remove(struct dnbd3_device *dev)
 {
 	struct gendisk *disk = dev->disk;
@@ -501,15 +585,9 @@ static void dnbd3_dev_remove(struct dnbd3_device *dev)
 	mutex_destroy(&dev->device_lock);
 }
 
-static void dnbd3_put(struct dnbd3_device *dnbd3)
-{
-	mutex_lock(&dnbd3_index_mutex);
-	idr_remove(&dnbd3_index_idr, dnbd3->minor);
-	mutex_unlock(&dnbd3_index_mutex);
-	dnbd3_dev_remove(dnbd3);
-}
-
-
+/**
+ * dnbd3_exit - exit the dnbd3 modul
+ */
 static void __exit dnbd3_exit(void)
 {
 	struct dnbd3_device *dnbd3;
@@ -524,7 +602,10 @@ static void __exit dnbd3_exit(void)
 		dnbd3 = list_first_entry(&del_list, struct dnbd3_device, list);
 		dnbd3_sysfs_exit(dnbd3);
 		list_del_init(&dnbd3->list);
-		dnbd3_put(dnbd3);
+		mutex_lock(&dnbd3_index_mutex);
+		idr_remove(&dnbd3_index_idr, dnbd3->minor);
+		mutex_unlock(&dnbd3_index_mutex);
+		dnbd3_dev_remove(dnbd3);
 	}
 
 	idr_destroy(&dnbd3_index_idr);