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/*
 * This file is part of the Distributed Network Block Device 3
 *
 * Copyright(c) 2019 Frederic Robra <frederic@robra.org>
 * Parts copyright 2011-2012 Johann Latocha <johann@latocha.de>
 *
 * This file may be licensed under the terms of of the
 * GNU General Public License Version 2 (the ``GPL'').
 *
 * Software distributed under the License is distributed
 * on an ``AS IS'' basis, WITHOUT WARRANTY OF ANY KIND, either
 * express or implied. See the GPL for the specific language
 * governing rights and limitations.
 *
 * You should have received a copy of the GPL along with this
 * program. If not, go to http://www.gnu.org/licenses/gpl.html
 * or write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 *
 */
#ifndef DNBD_H_
#define DNBD_H_

#include <linux/blk-mq.h>
#include <linux/types.h>
#include <linux/refcount.h>
#include <linux/blkdev.h>

#define KERNEL_MODULE
#include "types.h"
#include "serialize.h"


/**
 * factor to which the next server is choosen or the same
 */
#define RTT_FACTOR(rtt) (((rtt) * 3) / 2)


/**
 * turn on/off debug information (1/0)
 */
#define DEBUG 1
/**
 * turn on/off file and line information (1/0)
 */
#define DEBUG_FILE 1


//TODO test with ip tables regel. jedes x paket an port 58007 zerstoeren
// iptables -A OUTPUT -p tcp -m statistic --mode random --probability 0.1 -j REJECT  --reject-with tcp-reset
//TODO setup mit 2 vms eine langsam eine schnell tc (traffic control)
// -> geschwindigkkeit sollte in Richtung schnellen VM gehen mit 2 Queues

extern struct workqueue_struct *dnbd3_wq;

/**
 * struct dnbd3_server - defining a server for dnbd3
 * @host: host of this server
 * @rtts: last four round trip time measurements in microseconds
 * @protocol_version: dnbd3 protocol version of this server
 * @failures: how many times the server was unreachable
 */
struct dnbd3_server {
	dnbd3_host_t host;
	uint64_t rtts[4];
	uint64_t avg_rtt;
	uint16_t protocol_version;
	uint16_t failures;
};

/**
 * struct dnbd3_sock - defining a socket for dnbd3
 * @sock_nr: nr of this socket
 * @device: the dnbd3_device this socket belongs to
 * @server: the server this socket is connected to, 'NULL' if not connected
 * @tx_lock: mutex to lock when sending
 * @sock: the socket, 'NULL' if not connected
 * @panic: 'true' if it is not possible to send or receive
 * @cookie: is incremented for every send, used to find the mq request in the
 *          receiver
 * @keepalive_worker: worker to send a keepalive package
 * @receive_worker: worker to handle the incoming packages
 * @pending: the pending request which is going to be send
 */
struct dnbd3_sock {
	uint8_t sock_nr;
	struct dnbd3_device *device;
	struct dnbd3_server *server;

	struct mutex tx_lock;
	struct socket *sock;

//	bool panic;
	uint32_t cookie;

	struct work_struct keepalive_worker;
	struct work_struct receive_worker;

	struct request *pending;
};

/**
 * struct dnbd3_device - defining a dnbd3 device
 * @minor: minor number of this device
 * @tag_set: the blk mq tag set
 * @list: list of previous and next dnbd3_device
 * @disk: the gendisk
 * @kobj: the kobject
 * @device_lock: mutex to lock when device changes
 * @socks: array of dnbd3_sock to connect to
 * @imgname: the connected image name
 * @initial_server: the server which was configured with ioctl, will not be
 *                  overriden
 * @alt_servers: array of alternative servers
 * @new_servers_num: number of new alternative servers that are waiting to be
 *                   copied to above array
 * @new_servers: pending new alternative servers
 * @update_available: 'true' if the rid has changes
 * @use_server_provided_alts: 'true' if the alt_servers array is upated by the
 *                             alternatives provided by the server
 * @rid: the revision ID
 * @reported_size: the size of the image
 * @panic_worker: worker to handle panics and to connect if all connections are
 *                down
 * @discovery_worker: worker to update the alt_servers, make rtt meassurement
 *                    and reconnect to better servers
 * @discovery_count: counter for the discovery worker
 * @timer: timer to start the appropriate workers
 * @timer_count: counter for the timer
 */
struct dnbd3_device {
	int minor;
	struct blk_mq_tag_set tag_set;
	struct list_head list;

	struct gendisk *disk;

	struct kobject kobj;

	struct mutex device_lock;

	bool connected;
	uint8_t number_connections;
	struct dnbd3_sock *socks;
	char *imgname;
	struct dnbd3_server initial_server;
	struct dnbd3_server alt_servers[NUMBER_SERVERS];//TODO just add server to list do not remove
	int new_servers_num;
	dnbd3_server_entry_t new_servers[NUMBER_SERVERS];
	bool update_available;
	bool use_server_provided_alts;
	uint16_t rid;
	uint64_t reported_size;

	struct work_struct panic_worker;
	struct work_struct discovery_worker;
	uint8_t discovery_count;
	struct timer_list timer;
	uint8_t timer_count;
};


/**
 * struct dnbd3_cmd - defines a mq cmd for dnbd3
 * @dnbd3: the dnbd3 device this command belongs to
 * @lock: mutex to lock the cmd
 * @cookie: the cookie of the command, this is set by the socket when sending
 * @status: the status of the command
 * @requed: 'true' if the command is requed
 */
struct dnbd3_cmd {
	struct dnbd3_device *dnbd3;
	struct mutex lock;
	uint32_t cookie;
	uint32_t index;
	bool requed;
};





#define dnbd3_set_rtt_unreachable(server) \
	(server)->rtts[0] = (server)->rtts[1] = (server)->rtts[2] \
			= (server)->rtts[3] = (server)->avg_rtt = \
			RTT_UNREACHABLE;


#define dnbd3_set_rtt_unknown(server) \
	(server)->rtts[0] = (server)->rtts[1] = (server)->rtts[2] \
			= (server)->rtts[3] = 0;\
	(server)->avg_rtt = RTT_UNKNOWN;


/**
 * macros for logging
 * levels:
 * 	- debug
 * 	- info
 * 	- warn
 * 	- error
 * 	methods:
 * <level>(fmt,...)
 *         print fmt
 * <level>_dev(dev, fmt,...)
 *         print fmt, adds device information to the log
 * <level>_sock(sock, fmt,...)
 *         print fmt, adds sock and device information to log
 * <level>_server(dev, server, fmt,...)
 *         print fmt, adds device and appends server information to the log
 * DEBUG - 1/0 switch all debug messages on
 * DEBUG_FILE - 1/0 switch on file and line number information
 */


#if IS_ENABLED(DEBUG_FILE)

#define __print(level, fmt,...) \
	printk(level "%s:%d " fmt "\n", __FILE__, __LINE__, ## __VA_ARGS__)

#else

#define __print(level, fmt,...) \
	printk(level fmt "\n",  ## __VA_ARGS__)

#endif

#define __print_sock(level, sock, fmt, ...) \
	do { \
		if ((sock)->server->host.type == HOST_IP4) { \
			__print( \
					level, \
					"dnbd%d/%d %pI4:%d: " fmt, \
					(sock)->device->minor, \
					(sock)->sock_nr, \
					(sock)->server->host.addr, \
					(sock)->server->host.port, \
					## __VA_ARGS__); \
		} else { \
			__print( \
					level, \
					"dnbd%d/%d %pI6:%d: " fmt, \
					(sock)->device->minor, \
					(sock)->sock_nr, \
					(sock)->server->host.addr, \
					(sock)->server->host.port, \
					## __VA_ARGS__); \
		} \
	} while (0)

#define __print_server(level, dev, server, fmt, ...) \
	do { \
		if ((server)->host.type == HOST_IP4) { \
			__print( \
					level, \
					"dnbd%d: " fmt " %pI4:%d", \
					(dev)->minor, \
					## __VA_ARGS__, \
					(server)->host.addr, \
					(server)->host.port); \
		} else { \
			__print( \
					level, \
					"dnbd%d: " fmt " %pI6:%d", \
					(dev)->minor, \
					## __VA_ARGS__, \
					(server)->host.addr, \
					(server)->host.port); \
		} \
	} while (0)


#if IS_ENABLED(DEBUG)

#define debug(fmt, ...) \
	__print(KERN_DEBUG, "dnbd: " fmt, ## __VA_ARGS__)

#define debug_dev(dev, fmt, ...) \
	__print(KERN_DEBUG, "dnbd%d: " fmt, (dev)->minor, ## __VA_ARGS__)

#define debug_sock(sock, fmt, ...) \
	__print_sock(KERN_DEBUG, sock, fmt, ## __VA_ARGS__)

#define debug_server(dev, server, fmt, ...) \
	__print_server(KERN_DEBUG, dev, server, fmt, ## __VA_ARGS__)

#else

#define debug(fmt, ...)

#define debug_dev(dev, fmt, ...)

#define debug_sock(sock, fmt, ...)

#define debug_server(dev, server, fmt, ...)

#endif

#define info(fmt, ...) \
	__print(KERN_INFO, "dnbd: " fmt, ## __VA_ARGS__)

#define info_dev(dev, fmt, ...) \
	__print(KERN_INFO, "dnbd%d: " fmt, (dev)->minor, ## __VA_ARGS__)

#define info_sock(sock, fmt, ...) \
	__print_sock(KERN_INFO, sock, fmt, ## __VA_ARGS__)

#define info_server(dev, server, fmt, ...) \
	__print_server(KERN_INFO, dev, server, fmt, ## __VA_ARGS__)


#define warn(fmt, ...) \
	__print(KERN_WARNING, "dnbd: " fmt, ## __VA_ARGS__)

#define warn_dev(dev, fmt, ...) \
	__print(KERN_WARNING, "dnbd%d: " fmt, (dev)->minor, ## __VA_ARGS__)

#define warn_sock(sock, fmt, ...) \
	__print_sock(KERN_WARNING, sock, fmt, ## __VA_ARGS__)

#define warn_server(dev, server, fmt, ...) \
	__print_server(KERN_WARNING, dev, server, fmt, ## __VA_ARGS__)


#define error(fmt, ...) \
	__print(KERN_ERR, "dnbd: " fmt, ## __VA_ARGS__)

#define error_dev(dev, fmt, ...) \
	__print(KERN_ERR, "dnbd%d: " fmt, (dev)->minor, ## __VA_ARGS__)

#define error_sock(sock, fmt, ...) \
	__print_sock(KERN_ERR, sock, fmt, ## __VA_ARGS__)

#define error_server(dev, server, fmt, ...) \
	__print_server(KERN_ERR, dev, server, fmt, ## __VA_ARGS__)

#endif /* DNBD_H_ */