/*
 * This file is part of the Distributed Network Block Device 3
 *
 * Copyright(c) 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.
 *
 */

#include "clientconfig.h"
#include "blk.h"
#include "net.h"
#include "sysfs.h"

#include <linux/pagemap.h>

#if LINUX_VERSION_CODE >= KERNEL_VERSION(4, 11, 0)
#define dnbd3_req_read(req) \
	req_op(req) == REQ_OP_READ
#define dnbd3_req_fs(req) \
	dnbd3_req_read(req) || req_op(req) == REQ_OP_WRITE
#define dnbd3_req_special(req) \
	blk_rq_is_private(req)
#else
#define dnbd3_req_read(req) \
	rq_data_dir(req) == READ
#define dnbd3_req_fs(req) \
	req->cmd_type == REQ_TYPE_FS
#define dnbd3_req_special(req) \
	req->cmd_type == REQ_TYPE_SPECIAL
#endif

int dnbd3_blk_add_device(dnbd3_device_t *dev, int minor)
{
	struct gendisk *disk;
	struct request_queue *blk_queue;

	init_waitqueue_head(&dev->process_queue_send);
	init_waitqueue_head(&dev->process_queue_receive);
	init_waitqueue_head(&dev->process_queue_discover);
	INIT_LIST_HEAD(&dev->request_queue_send);
	INIT_LIST_HEAD(&dev->request_queue_receive);

	memset(&dev->cur_server, 0, sizeof(dev->cur_server));
	memset(&dev->initial_server, 0, sizeof(dev->initial_server));
	dev->better_sock = NULL;

	dev->imgname = NULL;
	dev->rid = 0;
	dev->update_available = 0;
	memset(dev->alt_servers, 0, sizeof(dev->alt_servers[0])*NUMBER_SERVERS);
	dev->thread_send = NULL;
	dev->thread_receive = NULL;
	dev->thread_discover = NULL;
	dev->discover = 0;
	dev->disconnecting = 0;
	dev->panic = 0;
	dev->panic_count = 0;
	dev->reported_size = 0;

	if (!(disk = alloc_disk(1)))
	{
		printk("ERROR: dnbd3 alloc_disk failed.\n");
		return -EIO;
	}

	disk->major = major;
	disk->first_minor = minor;
	sprintf(disk->disk_name, "dnbd%d", minor);
	set_capacity(disk, 0);
	set_disk_ro(disk, 1);
	disk->fops = &dnbd3_blk_ops;

	spin_lock_init(&dev->blk_lock);
	if ((blk_queue = blk_init_queue(&dnbd3_blk_request, &dev->blk_lock)) == NULL)
	{
		printk("ERROR: dnbd3 blk_init_queue failed.\n");
		return -EIO;
	}

	blk_queue_logical_block_size(blk_queue, DNBD3_BLOCK_SIZE);
	blk_queue_physical_block_size(blk_queue, DNBD3_BLOCK_SIZE);

	disk->queue = blk_queue;
	disk->private_data = dev;
#if LINUX_VERSION_CODE >= KERNEL_VERSION(4, 17, 0)
	blk_queue_flag_set(QUEUE_FLAG_NONROT, disk->queue);
	blk_queue_flag_clear(QUEUE_FLAG_ADD_RANDOM, disk->queue);
#else
	queue_flag_set_unlocked(QUEUE_FLAG_NONROT, disk->queue);
#endif
#define ONE_MEG (1048576)
	blk_queue_max_segment_size(disk->queue, ONE_MEG);
	blk_queue_max_segments(disk->queue, 0xffff);
	blk_queue_max_hw_sectors(disk->queue, ONE_MEG / DNBD3_BLOCK_SIZE);
	disk->queue->limits.max_sectors = 512;
	dev->disk = disk;
#undef ONE_MEG

	add_disk(disk);
	dnbd3_sysfs_init(dev);
	return 0;
}

int dnbd3_blk_del_device(dnbd3_device_t *dev)
{
	dnbd3_sysfs_exit(dev);
	dnbd3_net_disconnect(dev);
	del_gendisk(dev->disk);
	put_disk(dev->disk);
	blk_cleanup_queue(dev->disk->queue);
	return 0;
}

struct block_device_operations dnbd3_blk_ops =
	{ .owner = THIS_MODULE, .ioctl = dnbd3_blk_ioctl, };

int dnbd3_blk_ioctl(struct block_device *bdev, fmode_t mode, unsigned int cmd, unsigned long arg)
{
	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 = NULL;
	//unsigned long irqflags;

	while (dev->disconnecting)
	{
		// do nothing
	}

	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))
		{
			result = -ENOEXEC;
			goto cleanup_return;
		}
		if (copy_from_user((char *)msg, (char *)arg, sizeof(*msg)) != 0)
		{
			result = -ENOENT;
			goto cleanup_return;
		}
		if (msg->imgname != NULL && msg->imgnamelen > 0)
		{
			imgname = kmalloc(msg->imgnamelen + 1, GFP_KERNEL);
			if (imgname == NULL)
			{
				result = -ENOMEM;
				goto cleanup_return;
			}
			if (copy_from_user(imgname, msg->imgname, msg->imgnamelen) != 0)
			{
				result = -ENOENT;
				goto cleanup_return;
			}
			imgname[msg->imgnamelen] = '\0';
			//printk("IOCTL Image name of len %d is %s\n", (int)msg->imgnamelen, imgname);
		}
	}


	switch (cmd)
	{
	case IOCTL_OPEN:
		if (dev->imgname != NULL)
		{
			result = -EBUSY;
		}
		else if (imgname == NULL)
		{
			result = -EINVAL;
		}
		else if (msg == NULL)
		{
			result = -EINVAL;
		}
		else
		{
			if (sizeof(msg->host) != sizeof(dev->cur_server.host))
				printk("Odd size bug#1 triggered in IOCTL\n");
			memcpy(&dev->cur_server.host, &msg->host, sizeof(msg->host));
			dev->cur_server.failures = 0;
			memcpy(&dev->initial_server, &dev->cur_server, sizeof(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 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]));
#if LINUX_VERSION_CODE >= KERNEL_VERSION(4, 11, 0)
			if (blk_queue->backing_dev_info != NULL) {
				blk_queue->backing_dev_info->ra_pages = (msg->read_ahead_kb * 1024) / PAGE_SIZE;
			}
#else
			blk_queue->backing_dev_info.ra_pages = (msg->read_ahead_kb * 1024) / PAGE_SIZE;
#endif
			if (dnbd3_net_connect(dev) == 0)
			{
				result = 0;
				imgname = NULL; // Prevent kfree at the end
			}
			else
			{
				result = -ENOENT;
				dev->imgname = NULL;
			}
		}
		break;

	case IOCTL_CLOSE:
		dnbd3_blk_fail_all_requests(dev);
		result = dnbd3_net_disconnect(dev);
		dnbd3_blk_fail_all_requests(dev);
		set_capacity(dev->disk, 0);
		if (dev->imgname)
		{
			kfree(dev->imgname);
			dev->imgname = NULL;
		}
		break;

	case IOCTL_SWITCH:
		result = -EINVAL;
		break;

	case IOCTL_ADD_SRV:
	case IOCTL_REM_SRV:
		if (dev->imgname == NULL)
		{
			result = -ENOENT;
		}
		else if (dev->new_servers_num >= NUMBER_SERVERS)
		{
			result = -EAGAIN;
		}
		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
			++dev->new_servers_num;
			result = 0;
		}
		break;

	case BLKFLSBUF:
		result = 0;
		break;

	default:
		result = -EIO;
		break;
	}

cleanup_return:
	if (msg) kfree(msg);
	if (imgname) kfree(imgname);
	return result;
}

/**
 * dev->blk_lock and q->queue_lock are being held
 * when this is called!
 */
void dnbd3_blk_request(struct request_queue *q)
{
	struct request *req;
	dnbd3_device_t *dev;

	while ((req = blk_fetch_request(q)) != NULL)
	{
		dev = req->rq_disk->private_data;

		if (dev->imgname == NULL)
		{
			__blk_end_request_all(req, -EIO);
			continue;
		}

		if (!(dnbd3_req_fs(req)))
		{
			__blk_end_request_all(req, 0);
			continue;
		}

		if (PROBE_COUNT_TIMEOUT > 0 && dev->panic_count >= PROBE_COUNT_TIMEOUT)
		{
			__blk_end_request_all(req, -EIO);
			continue;
		}

		if (!(dnbd3_req_read(req)))
		{
			__blk_end_request_all(req, -EACCES);
			continue;
		}

		list_add_tail(&req->queuelist, &dev->request_queue_send);
		spin_unlock_irq(q->queue_lock);
		wake_up(&dev->process_queue_send);
		spin_lock_irq(q->queue_lock);
	}
}

void dnbd3_blk_fail_all_requests(dnbd3_device_t *dev)
{
	struct request *blk_request, *tmp_request;
	struct request *blk_request2, *tmp_request2;
	unsigned long flags;
	struct list_head local_copy;
	int dup;
	INIT_LIST_HEAD(&local_copy);
	spin_lock_irqsave(&dev->blk_lock, flags);
	while (!list_empty(&dev->request_queue_receive))
	{
		list_for_each_entry_safe(blk_request, tmp_request, &dev->request_queue_receive, queuelist)
		{
			list_del_init(&blk_request->queuelist);
			dup = 0;
			list_for_each_entry_safe(blk_request2, tmp_request2, &local_copy, queuelist)
			{
				if (blk_request == blk_request2)
				{
					printk("WARNING: Request is in both lists!\n");
					dup = 1;
					break;
				}
			}
			if (!dup) list_add(&blk_request->queuelist, &local_copy);
		}
	}
	while (!list_empty(&dev->request_queue_send))
	{
		list_for_each_entry_safe(blk_request, tmp_request, &dev->request_queue_send, queuelist)
		{
			list_del_init(&blk_request->queuelist);
			dup = 0;
			list_for_each_entry_safe(blk_request2, tmp_request2, &local_copy, queuelist)
			{
				if (blk_request == blk_request2)
				{
					printk("WARNING: Request is in both lists!\n");
					dup = 1;
					break;
				}
			}
			if (!dup) list_add(&blk_request->queuelist, &local_copy);
		}
	}
	spin_unlock_irqrestore(&dev->blk_lock, flags);
	list_for_each_entry_safe(blk_request, tmp_request, &local_copy, queuelist)
	{
		list_del_init(&blk_request->queuelist);
		if (dnbd3_req_fs(blk_request))
		{
			spin_lock_irqsave(&dev->blk_lock, flags);
			__blk_end_request_all(blk_request, -EIO);
			spin_unlock_irqrestore(&dev->blk_lock, flags);
		}
		else if (dnbd3_req_special(blk_request))
		{
			kfree(blk_request);
		}
	}
}