/*
 *
 * Copyright (c) 2009, Microsoft Corporation.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program; if not, write to the Free Software Foundation, Inc., 59 Temple
 * Place - Suite 330, Boston, MA 02111-1307 USA.
 *
 * Authors:
 *   Hank Janssen  <hjanssen@microsoft.com>
 *
 */

#define KERNEL_2_6_27

#include <linux/init.h>
#include <linux/module.h>
#include <linux/device.h>
#include <linux/blkdev.h>
#include <linux/major.h>
#include <linux/delay.h>
#include <linux/hdreg.h>

#include <scsi/scsi.h>
#include <scsi/scsi_cmnd.h>
#include <scsi/scsi_eh.h>
#include <scsi/scsi_dbg.h>

#include "include/logging.h"
#include "include/vmbus.h"

#include "include/StorVscApi.h"

//
// #defines
//
#define BLKVSC_MINORS	64

//
// Data types
//
enum blkvsc_device_type {
	UNKNOWN_DEV_TYPE,
	HARDDISK_TYPE,
	DVD_TYPE,
};

// This request ties the struct request and struct blkvsc_request/STORVSC_REQUEST together
// A struct request may be represented by 1 or more struct blkvsc_request
struct blkvsc_request_group {
	int					outstanding;
	int					status;

	struct list_head	blkvsc_req_list;	// list of blkvsc_requests
};


struct blkvsc_request {
	struct list_head	req_entry;			// blkvsc_request_group.blkvsc_req_list

	struct list_head	pend_entry;			// block_device_context.pending_list

	struct request		*req;				// This may be null if we generate a request internally
	struct block_device_context	*dev;
	struct blkvsc_request_group	*group;		// The group this request is part of. Maybe null

	wait_queue_head_t	wevent;
	int cond;

	int					write;
	sector_t			sector_start;
	unsigned long		sector_count;

	unsigned char sense_buffer[SCSI_SENSE_BUFFERSIZE];
	unsigned char cmd_len;
	unsigned char cmnd[MAX_COMMAND_SIZE];

	STORVSC_REQUEST		request;
	// !!!DO NOT ADD ANYTHING BELOW HERE!!! Otherwise, memory can overlap, because -
	// The extension buffer falls right here and is pointed to by request.Extension;
};

// Per device structure
struct block_device_context {
	struct device_context	*device_ctx; // point back to our device context
	struct kmem_cache	*request_pool;
	spinlock_t				lock;
	struct gendisk			*gd;
	enum blkvsc_device_type	device_type;
	struct list_head		pending_list;

	unsigned char			device_id[64];
	unsigned int			device_id_len;
	int						num_outstanding_reqs;
	int						shutting_down;
	int						media_not_present;
	unsigned int			sector_size;
	sector_t				capacity;
	unsigned int			port;
	unsigned char			path;
	unsigned char			target;
	int						users;
};

// Per driver
struct blkvsc_driver_context {
	// !! These must be the first 2 fields !!
	struct driver_context	drv_ctx;
	STORVSC_DRIVER_OBJECT	drv_obj;
};

// Static decl
static int blkvsc_probe(struct device *dev);
static int blkvsc_remove(struct device *device);
static void blkvsc_shutdown(struct device *device);

static int blkvsc_open(struct inode *inode, struct file *filep);
static int blkvsc_release(struct inode *inode, struct file *filep);
static int blkvsc_media_changed(struct gendisk *gd);
static int blkvsc_revalidate_disk(struct gendisk *gd);
static int blkvsc_getgeo(struct block_device *bd, struct hd_geometry *hg);
static int blkvsc_ioctl(struct inode *inode, struct file *filep, unsigned cmd, unsigned long arg);

static void blkvsc_request(struct request_queue *queue);
static void blkvsc_request_completion(STORVSC_REQUEST* request);
static int blkvsc_do_request(struct block_device_context *blkdev, struct request *req);
static int blkvsc_submit_request(struct blkvsc_request *blkvsc_req, void (*request_completion)(STORVSC_REQUEST*) );
static void blkvsc_init_rw(struct blkvsc_request *blkvsc_req);
static void blkvsc_cmd_completion(STORVSC_REQUEST* request);
static int blkvsc_do_inquiry(struct block_device_context *blkdev);
static int blkvsc_do_read_capacity(struct block_device_context *blkdev);
static int blkvsc_do_read_capacity16(struct block_device_context *blkdev);
static int blkvsc_do_flush(struct block_device_context *blkdev);
static int blkvsc_cancel_pending_reqs(struct block_device_context *blkdev);
static int blkvsc_do_pending_reqs(struct block_device_context *blkdev);


static int blkvsc_ringbuffer_size = BLKVSC_RING_BUFFER_SIZE;

// The one and only one
static struct blkvsc_driver_context g_blkvsc_drv;


static struct block_device_operations block_ops =
{
	.owner = THIS_MODULE,
	.open = blkvsc_open,
	.release = blkvsc_release,
	.media_changed = blkvsc_media_changed,
	.revalidate_disk = blkvsc_revalidate_disk,
	.getgeo = blkvsc_getgeo,
	.ioctl  = blkvsc_ioctl,
};

/*++

Name:	blkvsc_drv_init()

Desc:	BlkVsc driver initialization.

--*/
int blkvsc_drv_init(PFN_DRIVERINITIALIZE pfn_drv_init)
{
	int ret=0;
	STORVSC_DRIVER_OBJECT *storvsc_drv_obj=&g_blkvsc_drv.drv_obj;
	struct driver_context *drv_ctx=&g_blkvsc_drv.drv_ctx;

	DPRINT_ENTER(BLKVSC_DRV);

	vmbus_get_interface(&storvsc_drv_obj->Base.VmbusChannelInterface);

	storvsc_drv_obj->RingBufferSize = blkvsc_ringbuffer_size;

	// Callback to client driver to complete the initialization
	pfn_drv_init(&storvsc_drv_obj->Base);

	drv_ctx->driver.name = storvsc_drv_obj->Base.name;
	memcpy(&drv_ctx->class_id, &storvsc_drv_obj->Base.deviceType, sizeof(GUID));

#if defined(KERNEL_2_6_5) || defined(KERNEL_2_6_9)
	drv_ctx->driver.probe = blkvsc_probe;
	drv_ctx->driver.remove = blkvsc_remove;
#else
	drv_ctx->probe = blkvsc_probe;
	drv_ctx->remove = blkvsc_remove;
	drv_ctx->shutdown = blkvsc_shutdown;
#endif

	// The driver belongs to vmbus
	vmbus_child_driver_register(drv_ctx);

	DPRINT_EXIT(BLKVSC_DRV);

	return ret;
}


static int blkvsc_drv_exit_cb(struct device *dev, void *data)
{
	struct device **curr = (struct device **)data;
	*curr = dev;
	return 1; // stop iterating
}

/*++

Name:	blkvsc_drv_exit()

Desc:

--*/
void blkvsc_drv_exit(void)
{
	STORVSC_DRIVER_OBJECT *storvsc_drv_obj=&g_blkvsc_drv.drv_obj;
	struct driver_context *drv_ctx=&g_blkvsc_drv.drv_ctx;

	struct device *current_dev=NULL;

#if defined(KERNEL_2_6_5) || defined(KERNEL_2_6_9)
#define driver_for_each_device(drv, start, data, fn) \
	struct list_head *ptr, *n; \
	list_for_each_safe(ptr, n, &((drv)->devices)) {\
		struct device *curr_dev;\
		curr_dev = list_entry(ptr, struct device, driver_list);\
		fn(curr_dev, data);\
	}
#endif // KERNEL_2_6_9

	DPRINT_ENTER(BLKVSC_DRV);

	while (1)
	{
		current_dev = NULL;

		// Get the device
		driver_for_each_device(&drv_ctx->driver, NULL, (void*)&current_dev, blkvsc_drv_exit_cb);

		if (current_dev == NULL)
			break;

		// Initiate removal from the top-down
		device_unregister(current_dev);
	}

	if (storvsc_drv_obj->Base.OnCleanup)
		storvsc_drv_obj->Base.OnCleanup(&storvsc_drv_obj->Base);

	vmbus_child_driver_unregister(drv_ctx);

	DPRINT_EXIT(BLKVSC_DRV);

	return;
}

/*++

Name:	blkvsc_probe()

Desc:	Add a new device for this driver

--*/
static int blkvsc_probe(struct device *device)
{
	int ret=0;

	struct driver_context *driver_ctx = driver_to_driver_context(device->driver);
	struct blkvsc_driver_context *blkvsc_drv_ctx = (struct blkvsc_driver_context*)driver_ctx;
	STORVSC_DRIVER_OBJECT* storvsc_drv_obj = &blkvsc_drv_ctx->drv_obj;

	struct device_context *device_ctx = device_to_device_context(device);
	DEVICE_OBJECT* device_obj = &device_ctx->device_obj;

	struct block_device_context *blkdev=NULL;
	STORVSC_DEVICE_INFO device_info;
	int major=0;
	int devnum=0;

	static int ide0_registered=0;
	static int ide1_registered=0;

	DPRINT_ENTER(BLKVSC_DRV);

	DPRINT_DBG(BLKVSC_DRV, "blkvsc_probe - enter");

	if (!storvsc_drv_obj->Base.OnDeviceAdd)
	{
		DPRINT_ERR(BLKVSC_DRV, "OnDeviceAdd() not set");

		ret = -1;
		goto Cleanup;
	}

	blkdev = kzalloc(sizeof(struct block_device_context), GFP_KERNEL);
	if (!blkdev)
	{
		ret = -ENOMEM;
		goto Cleanup;
	}

	INIT_LIST_HEAD(&blkdev->pending_list);

	// Initialize what we can here
	spin_lock_init(&blkdev->lock);

	ASSERT(sizeof(struct blkvsc_request_group) <= sizeof(struct blkvsc_request));

#ifdef KERNEL_2_6_27
        blkdev->request_pool = kmem_cache_create(dev_name(&device_ctx->device),
                sizeof(struct blkvsc_request) + storvsc_drv_obj->RequestExtSize, 0,
                SLAB_HWCACHE_ALIGN, NULL);
#else
	blkdev->request_pool = kmem_cache_create(device_ctx->device.bus_id,
		sizeof(struct blkvsc_request) + storvsc_drv_obj->RequestExtSize, 0,
		SLAB_HWCACHE_ALIGN, NULL, NULL);
#endif
	if (!blkdev->request_pool)
	{
		ret = -ENOMEM;
		goto Cleanup;
	}


	// Call to the vsc driver to add the device
	ret = storvsc_drv_obj->Base.OnDeviceAdd(device_obj, &device_info);
	if (ret != 0)
	{
		DPRINT_ERR(BLKVSC_DRV, "unable to add blkvsc device");
		goto Cleanup;
	}

	blkdev->device_ctx = device_ctx;
	blkdev->target = device_info.TargetId; // this identified the device 0 or 1
	blkdev->path = device_info.PathId; // this identified the ide ctrl 0 or 1

	dev_set_drvdata(device, blkdev);

	// Calculate the major and device num
	if (blkdev->path == 0)
	{
		major = IDE0_MAJOR;
		devnum = blkdev->path + blkdev->target;		// 0 or 1

		if (!ide0_registered)
		{
			ret = register_blkdev(major, "ide");
			if (ret != 0)
			{
				DPRINT_ERR(BLKVSC_DRV, "register_blkdev() failed! ret %d", ret);
				goto Remove;
			}

			ide0_registered = 1;
		}
	}
	else if (blkdev->path == 1)
	{
		major = IDE1_MAJOR;
		devnum = blkdev->path + blkdev->target + 1; // 2 or 3

		if (!ide1_registered)
		{
			ret = register_blkdev(major, "ide");
			if (ret != 0)
			{
				DPRINT_ERR(BLKVSC_DRV, "register_blkdev() failed! ret %d", ret);
				goto Remove;
			}

			ide1_registered = 1;
		}

	}
	else
	{
		DPRINT_ERR(BLKVSC_DRV, "invalid pathid");
		ret = -1;
		goto Cleanup;
	}

	DPRINT_INFO(BLKVSC_DRV, "blkvsc registered for major %d!!", major);

	blkdev->gd = alloc_disk(BLKVSC_MINORS);
	if (!blkdev->gd)
	{
		DPRINT_ERR(BLKVSC_DRV, "register_blkdev() failed! ret %d", ret);
		ret = -1;
		goto Cleanup;
	}

	blkdev->gd->queue = blk_init_queue(blkvsc_request, &blkdev->lock);

	blk_queue_max_segment_size(blkdev->gd->queue, PAGE_SIZE);
	blk_queue_max_phys_segments(blkdev->gd->queue, MAX_MULTIPAGE_BUFFER_COUNT);
	blk_queue_max_hw_segments(blkdev->gd->queue, MAX_MULTIPAGE_BUFFER_COUNT);
	blk_queue_segment_boundary(blkdev->gd->queue, PAGE_SIZE-1);
	blk_queue_bounce_limit(blkdev->gd->queue, BLK_BOUNCE_ANY);
	blk_queue_dma_alignment(blkdev->gd->queue, 511);

	blkdev->gd->major = major;
	if (devnum == 1 || devnum == 3)
		blkdev->gd->first_minor = BLKVSC_MINORS;
	else
		blkdev->gd->first_minor = 0;
	blkdev->gd->fops = &block_ops;
	blkdev->gd->private_data = blkdev;
	sprintf(blkdev->gd->disk_name, "hd%c", 'a'+ devnum);

	blkvsc_do_inquiry(blkdev);
	if (blkdev->device_type == DVD_TYPE)
	{
		set_disk_ro(blkdev->gd, 1);
		blkdev->gd->flags |= GENHD_FL_REMOVABLE;
		blkvsc_do_read_capacity(blkdev);
	}
	else
	{
		blkvsc_do_read_capacity16(blkdev);
	}

	set_capacity(blkdev->gd, blkdev->capacity * (blkdev->sector_size/512));
	blk_queue_logical_block_size(blkdev->gd->queue, blkdev->sector_size);
	// go!
	add_disk(blkdev->gd);

	DPRINT_INFO(BLKVSC_DRV, "%s added!! capacity %llu sector_size %d", blkdev->gd->disk_name, blkdev->capacity, blkdev->sector_size);

	return ret;

Remove:
	storvsc_drv_obj->Base.OnDeviceRemove(device_obj);

Cleanup:
	if (blkdev)
	{
		if (blkdev->request_pool)
		{
			kmem_cache_destroy(blkdev->request_pool);
			blkdev->request_pool = NULL;
		}
		kfree(blkdev);
		blkdev = NULL;
	}

	DPRINT_EXIT(BLKVSC_DRV);

	return ret;
}

static void blkvsc_shutdown(struct device *device)
{
	struct block_device_context *blkdev = dev_get_drvdata(device);
	unsigned long flags;

	if (!blkdev)
		return;

	DPRINT_DBG(BLKVSC_DRV, "blkvsc_shutdown - users %d disk %s\n", blkdev->users, blkdev->gd->disk_name);

	spin_lock_irqsave(&blkdev->lock, flags);

	blkdev->shutting_down = 1;

	blk_stop_queue(blkdev->gd->queue);

	spin_unlock_irqrestore(&blkdev->lock, flags);

	while (blkdev->num_outstanding_reqs)
	{
		DPRINT_INFO(STORVSC, "waiting for %d requests to complete...", blkdev->num_outstanding_reqs);

		udelay(100);
	}

	blkvsc_do_flush(blkdev);

	spin_lock_irqsave(&blkdev->lock, flags);

	blkvsc_cancel_pending_reqs(blkdev);

	spin_unlock_irqrestore(&blkdev->lock, flags);
}

static int blkvsc_do_flush(struct block_device_context *blkdev)
{
	struct blkvsc_request *blkvsc_req=NULL;

	DPRINT_DBG(BLKVSC_DRV, "blkvsc_do_flush()\n");

	if (blkdev->device_type != HARDDISK_TYPE)
		return 0;

	blkvsc_req = kmem_cache_alloc(blkdev->request_pool, GFP_KERNEL);
	if (!blkvsc_req)
	{
		return -ENOMEM;
	}

	memset(blkvsc_req, 0, sizeof(struct blkvsc_request));
	init_waitqueue_head(&blkvsc_req->wevent);
	blkvsc_req->dev = blkdev;
	blkvsc_req->req = NULL;
	blkvsc_req->write = 0;

	blkvsc_req->request.DataBuffer.PfnArray[0] = 0;
	blkvsc_req->request.DataBuffer.Offset = 0;
	blkvsc_req->request.DataBuffer.Length = 0;

	blkvsc_req->cmnd[0] = SYNCHRONIZE_CACHE;
	blkvsc_req->cmd_len = 10;

	// Set this here since the completion routine may be invoked and completed before we return
	blkvsc_req->cond =0;
	blkvsc_submit_request(blkvsc_req, blkvsc_cmd_completion);

	wait_event_interruptible(blkvsc_req->wevent, blkvsc_req->cond);

	kmem_cache_free(blkvsc_req->dev->request_pool, blkvsc_req);

	return 0;
}

// Do a scsi INQUIRY cmd here to get the device type (ie disk or dvd)
static int blkvsc_do_inquiry(struct block_device_context *blkdev)
{
	struct blkvsc_request *blkvsc_req=NULL;
	struct page *page_buf;
	unsigned char *buf;
	unsigned char device_type;

	DPRINT_DBG(BLKVSC_DRV, "blkvsc_do_inquiry()\n");

	blkvsc_req = kmem_cache_alloc(blkdev->request_pool, GFP_KERNEL);
	if (!blkvsc_req)
	{
		return -ENOMEM;
	}

	memset(blkvsc_req, 0, sizeof(struct blkvsc_request));
	page_buf = alloc_page(GFP_KERNEL);
	if (!page_buf)
	{
		kmem_cache_free(blkvsc_req->dev->request_pool, blkvsc_req);
		return -ENOMEM;
	}

	init_waitqueue_head(&blkvsc_req->wevent);
	blkvsc_req->dev = blkdev;
	blkvsc_req->req = NULL;
	blkvsc_req->write = 0;

	blkvsc_req->request.DataBuffer.PfnArray[0] = page_to_pfn(page_buf);
	blkvsc_req->request.DataBuffer.Offset = 0;
	blkvsc_req->request.DataBuffer.Length = 64;

	blkvsc_req->cmnd[0] = INQUIRY;
	blkvsc_req->cmnd[1] = 0x1;		// Get product data
	blkvsc_req->cmnd[2] = 0x83;		// mode page 83
	blkvsc_req->cmnd[4] = 64;
	blkvsc_req->cmd_len = 6;

	// Set this here since the completion routine may be invoked and completed before we return
	blkvsc_req->cond =0;

	blkvsc_submit_request(blkvsc_req, blkvsc_cmd_completion);

	DPRINT_DBG(BLKVSC_DRV, "waiting %p to complete - cond %d\n", blkvsc_req, blkvsc_req->cond);

	wait_event_interruptible(blkvsc_req->wevent, blkvsc_req->cond);

	buf = kmap(page_buf);

	//PrintBytes(buf, 64);
	// be to le
	device_type = buf[0] & 0x1F;

	if (device_type == 0x0)
	{
		blkdev->device_type = HARDDISK_TYPE;
	}
	else if (device_type == 0x5)
	{
		blkdev->device_type = DVD_TYPE;
	}
	else
	{
		// TODO: this is currently unsupported device type
		blkdev->device_type = UNKNOWN_DEV_TYPE;
	}

	DPRINT_DBG(BLKVSC_DRV, "device type %d \n", device_type);

	blkdev->device_id_len = buf[7];
	if (blkdev->device_id_len > 64)
		blkdev->device_id_len = 64;

	memcpy(blkdev->device_id, &buf[8], blkdev->device_id_len);
	//PrintBytes(blkdev->device_id, blkdev->device_id_len);

	kunmap(page_buf);

	__free_page(page_buf);

	kmem_cache_free(blkvsc_req->dev->request_pool, blkvsc_req);

	return 0;
}

// Do a scsi READ_CAPACITY cmd here to get the size of the disk
static int blkvsc_do_read_capacity(struct block_device_context *blkdev)
{
	struct blkvsc_request *blkvsc_req=NULL;
	struct page *page_buf;
	unsigned char *buf;
	struct scsi_sense_hdr sense_hdr;

	DPRINT_DBG(BLKVSC_DRV, "blkvsc_do_read_capacity()\n");

	blkdev->sector_size = 0;
	blkdev->capacity = 0;
	blkdev->media_not_present = 0; // assume a disk is present

	blkvsc_req = kmem_cache_alloc(blkdev->request_pool, GFP_KERNEL);
	if (!blkvsc_req)
	{
		return -ENOMEM;
	}

	memset(blkvsc_req, 0, sizeof(struct blkvsc_request));
	page_buf = alloc_page(GFP_KERNEL);
	if (!page_buf)
	{
		kmem_cache_free(blkvsc_req->dev->request_pool, blkvsc_req);
		return -ENOMEM;
	}

	init_waitqueue_head(&blkvsc_req->wevent);
	blkvsc_req->dev = blkdev;
	blkvsc_req->req = NULL;
	blkvsc_req->write = 0;

	blkvsc_req->request.DataBuffer.PfnArray[0] = page_to_pfn(page_buf);
	blkvsc_req->request.DataBuffer.Offset = 0;
	blkvsc_req->request.DataBuffer.Length = 8;

	blkvsc_req->cmnd[0] = READ_CAPACITY;
	blkvsc_req->cmd_len = 16;

	// Set this here since the completion routine may be invoked and completed before we return
	blkvsc_req->cond =0;

	blkvsc_submit_request(blkvsc_req, blkvsc_cmd_completion);

	DPRINT_DBG(BLKVSC_DRV, "waiting %p to complete - cond %d\n", blkvsc_req, blkvsc_req->cond);

	wait_event_interruptible(blkvsc_req->wevent, blkvsc_req->cond);

	// check error
	if (blkvsc_req->request.Status)
	{
		scsi_normalize_sense(blkvsc_req->sense_buffer, SCSI_SENSE_BUFFERSIZE, &sense_hdr);

		if (sense_hdr.asc == 0x3A) // Medium not present
		{
			blkdev->media_not_present = 1;
		}

		return 0;
	}
	buf = kmap(page_buf);

	// be to le
	blkdev->capacity = ((buf[0] << 24) | (buf[1] << 16) | (buf[2] << 8) | buf[3]) + 1;
	blkdev->sector_size = (buf[4] << 24) | (buf[5] << 16) | (buf[6] << 8) | buf[7];

	kunmap(page_buf);

	__free_page(page_buf);

	kmem_cache_free(blkvsc_req->dev->request_pool, blkvsc_req);

	return 0;
}


static int blkvsc_do_read_capacity16(struct block_device_context *blkdev)
{
	struct blkvsc_request *blkvsc_req=NULL;
	struct page *page_buf;
	unsigned char *buf;
	struct scsi_sense_hdr sense_hdr;

	DPRINT_DBG(BLKVSC_DRV, "blkvsc_do_read_capacity16()\n");

	blkdev->sector_size = 0;
	blkdev->capacity = 0;
	blkdev->media_not_present = 0; // assume a disk is present

	blkvsc_req = kmem_cache_alloc(blkdev->request_pool, GFP_KERNEL);
	if (!blkvsc_req)
	{
		return -ENOMEM;
	}

	memset(blkvsc_req, 0, sizeof(struct blkvsc_request));
	page_buf = alloc_page(GFP_KERNEL);
	if (!page_buf)
	{
		kmem_cache_free(blkvsc_req->dev->request_pool, blkvsc_req);
		return -ENOMEM;
	}

	init_waitqueue_head(&blkvsc_req->wevent);
	blkvsc_req->dev = blkdev;
	blkvsc_req->req = NULL;
	blkvsc_req->write = 0;

	blkvsc_req->request.DataBuffer.PfnArray[0] = page_to_pfn(page_buf);
	blkvsc_req->request.DataBuffer.Offset = 0;
	blkvsc_req->request.DataBuffer.Length = 12;

	blkvsc_req->cmnd[0] = 0x9E; //READ_CAPACITY16;
	blkvsc_req->cmd_len = 16;

	// Set this here since the completion routine may be invoked and completed before we return
	blkvsc_req->cond =0;

	blkvsc_submit_request(blkvsc_req, blkvsc_cmd_completion);

	DPRINT_DBG(BLKVSC_DRV, "waiting %p to complete - cond %d\n", blkvsc_req, blkvsc_req->cond);

	wait_event_interruptible(blkvsc_req->wevent, blkvsc_req->cond);

	// check error
	if (blkvsc_req->request.Status)
	{
		scsi_normalize_sense(blkvsc_req->sense_buffer, SCSI_SENSE_BUFFERSIZE, &sense_hdr);

		if (sense_hdr.asc == 0x3A) // Medium not present
		{
			blkdev->media_not_present = 1;
		}

		return 0;
	}
	buf = kmap(page_buf);

	// be to le
	blkdev->capacity = be64_to_cpu(*(unsigned long long*) &buf[0]) + 1;
	blkdev->sector_size = be32_to_cpu(*(unsigned int*)&buf[8]);

	//blkdev->capacity = ((buf[0] << 24) | (buf[1] << 16) | (buf[2] << 8) | buf[3]) + 1;
	//blkdev->sector_size = (buf[4] << 24) | (buf[5] << 16) | (buf[6] << 8) | buf[7];

	kunmap(page_buf);

	__free_page(page_buf);

	kmem_cache_free(blkvsc_req->dev->request_pool, blkvsc_req);

	return 0;
}

/*++

Name:	blkvsc_remove()

Desc:	Callback when our device is removed

--*/
static int blkvsc_remove(struct device *device)
{
	int ret=0;

	struct driver_context *driver_ctx = driver_to_driver_context(device->driver);
	struct blkvsc_driver_context *blkvsc_drv_ctx = (struct blkvsc_driver_context*)driver_ctx;
	STORVSC_DRIVER_OBJECT* storvsc_drv_obj = &blkvsc_drv_ctx->drv_obj;

	struct device_context *device_ctx = device_to_device_context(device);
	DEVICE_OBJECT* device_obj = &device_ctx->device_obj;
	struct block_device_context *blkdev = dev_get_drvdata(device);
	unsigned long flags;

	DPRINT_ENTER(BLKVSC_DRV);

	DPRINT_DBG(BLKVSC_DRV, "blkvsc_remove()\n");

	if (!storvsc_drv_obj->Base.OnDeviceRemove)
	{
		DPRINT_EXIT(BLKVSC_DRV);
		return -1;
	}

	// Call to the vsc driver to let it know that the device is being removed
	ret = storvsc_drv_obj->Base.OnDeviceRemove(device_obj);
	if (ret != 0)
	{
		// TODO:
		DPRINT_ERR(BLKVSC_DRV, "unable to remove blkvsc device (ret %d)", ret);
	}

	// Get to a known state
	spin_lock_irqsave(&blkdev->lock, flags);

	blkdev->shutting_down = 1;

	blk_stop_queue(blkdev->gd->queue);

	spin_unlock_irqrestore(&blkdev->lock, flags);

	while (blkdev->num_outstanding_reqs)
	{
		DPRINT_INFO(STORVSC, "waiting for %d requests to complete...", blkdev->num_outstanding_reqs);

		udelay(100);
	}

	blkvsc_do_flush(blkdev);

	spin_lock_irqsave(&blkdev->lock, flags);

	blkvsc_cancel_pending_reqs(blkdev);

	spin_unlock_irqrestore(&blkdev->lock, flags);

	blk_cleanup_queue(blkdev->gd->queue);

	del_gendisk(blkdev->gd);

	kmem_cache_destroy(blkdev->request_pool);

	kfree(blkdev);

	DPRINT_EXIT(BLKVSC_DRV);

	return ret;
}

static void blkvsc_init_rw(struct blkvsc_request *blkvsc_req)
{
	ASSERT(blkvsc_req->req);
	ASSERT(blkvsc_req->sector_count <= (MAX_MULTIPAGE_BUFFER_COUNT*8));

	blkvsc_req->cmd_len = 16;

	if (blkvsc_req->sector_start > 0xffffffff)
	{
		if (rq_data_dir(blkvsc_req->req))
		{
			blkvsc_req->write = 1;
			blkvsc_req->cmnd[0] = WRITE_16;
		}
		else
		{
			blkvsc_req->write = 0;
			blkvsc_req->cmnd[0] = READ_16;
		}

		blkvsc_req->cmnd[1] |= blk_fua_rq(blkvsc_req->req) ? 0x8 : 0;

		*(unsigned long long*)&blkvsc_req->cmnd[2] = cpu_to_be64(blkvsc_req->sector_start);
		*(unsigned int*)&blkvsc_req->cmnd[10] = cpu_to_be32(blkvsc_req->sector_count);
	}
	else if ((blkvsc_req->sector_count > 0xff) || (blkvsc_req->sector_start > 0x1fffff))
	{
		if (rq_data_dir(blkvsc_req->req))
		{
			blkvsc_req->write = 1;
			blkvsc_req->cmnd[0] = WRITE_10;
		}
		else
		{
			blkvsc_req->write = 0;
			blkvsc_req->cmnd[0] = READ_10;
		}

		blkvsc_req->cmnd[1] |= blk_fua_rq(blkvsc_req->req) ? 0x8 : 0;

		*(unsigned int *)&blkvsc_req->cmnd[2] = cpu_to_be32(blkvsc_req->sector_start);
		*(unsigned short*)&blkvsc_req->cmnd[7] = cpu_to_be16(blkvsc_req->sector_count);
    }
	else
	{
		if (rq_data_dir(blkvsc_req->req))
		{
			blkvsc_req->write = 1;
			blkvsc_req->cmnd[0] = WRITE_6;
		}
		else
		{
			blkvsc_req->write = 0;
			blkvsc_req->cmnd[0] = READ_6;
		}

		*(unsigned int *)&blkvsc_req->cmnd[1] = cpu_to_be32(blkvsc_req->sector_start) >> 8;
		blkvsc_req->cmnd[1] &= 0x1f;
		blkvsc_req->cmnd[4] = (unsigned char) blkvsc_req->sector_count;
	}
}

static int blkvsc_submit_request(struct blkvsc_request *blkvsc_req, void (*request_completion)(STORVSC_REQUEST*) )
{
	struct block_device_context *blkdev = blkvsc_req->dev;
	struct device_context *device_ctx=blkdev->device_ctx;
	struct driver_context *driver_ctx = driver_to_driver_context(device_ctx->device.driver);
	struct blkvsc_driver_context *blkvsc_drv_ctx = (struct blkvsc_driver_context*)driver_ctx;
	STORVSC_DRIVER_OBJECT* storvsc_drv_obj = &blkvsc_drv_ctx->drv_obj;
	int ret =0;

	STORVSC_REQUEST *storvsc_req;

	DPRINT_DBG(BLKVSC_DRV, "blkvsc_submit_request() - req %p type %s start_sector %llu count %d offset %d len %d\n",
		blkvsc_req,
		(blkvsc_req->write)?"WRITE":"READ",
		blkvsc_req->sector_start,
		blkvsc_req->sector_count,
		blkvsc_req->request.DataBuffer.Offset,
		blkvsc_req->request.DataBuffer.Length);

	/*for (i=0; i < (blkvsc_req->request.DataBuffer.Length >> 12); i++)
	{
		DPRINT_DBG(BLKVSC_DRV, "blkvsc_submit_request() - req %p pfn[%d] %llx\n",
		blkvsc_req,
		i,
		blkvsc_req->request.DataBuffer.PfnArray[i]);
	}*/

	storvsc_req = &blkvsc_req->request;
	storvsc_req->Extension = (void*)((unsigned long)blkvsc_req + sizeof(struct blkvsc_request));

	storvsc_req->Type = blkvsc_req->write? WRITE_TYPE : READ_TYPE;

	storvsc_req->OnIOCompletion = request_completion;
	storvsc_req->Context = blkvsc_req;

	storvsc_req->Host = blkdev->port;
	storvsc_req->Bus = blkdev->path;
	storvsc_req->TargetId = blkdev->target;
	storvsc_req->LunId = 0;	 // this is not really used at all

	storvsc_req->CdbLen = blkvsc_req->cmd_len;
	storvsc_req->Cdb = blkvsc_req->cmnd;

	storvsc_req->SenseBuffer = blkvsc_req->sense_buffer;
	storvsc_req->SenseBufferSize = SCSI_SENSE_BUFFERSIZE;

	ret = storvsc_drv_obj->OnIORequest(&blkdev->device_ctx->device_obj, &blkvsc_req->request);
	if (ret == 0)
	{
		blkdev->num_outstanding_reqs++;
	}

	return ret;
}

//
// We break the request into 1 or more blkvsc_requests and submit them.
// If we cant submit them all, we put them on the pending_list. The
// blkvsc_request() will work on the pending_list.
//
static int blkvsc_do_request(struct block_device_context *blkdev, struct request *req)
{
	struct bio *bio=NULL;
	struct bio_vec *bvec=NULL;
	struct bio_vec *prev_bvec=NULL;

	struct blkvsc_request *blkvsc_req=NULL;
	struct blkvsc_request *tmp;
	int databuf_idx=0;
	int seg_idx=0;

	sector_t start_sector;
	unsigned long num_sectors = 0;
	int ret=0;
	int pending=0;
	struct blkvsc_request_group *group=NULL;

	DPRINT_DBG(BLKVSC_DRV, "blkdev %p req %p sect %llu \n", blkdev, req, blk_rq_pos(req));

	// Create a group to tie req to list of blkvsc_reqs
	group = (struct blkvsc_request_group*)kmem_cache_alloc(blkdev->request_pool, GFP_ATOMIC);
	if (!group)
	{
		return -ENOMEM;
	}

	INIT_LIST_HEAD(&group->blkvsc_req_list);
	group->outstanding = group->status = 0;

	start_sector = blk_rq_pos(req);

	// foreach bio in the request
	if (req->bio)
	 for (bio = req->bio; bio; bio = bio->bi_next)
	{
		// Map this bio into an existing or new storvsc request
		bio_for_each_segment (bvec, bio, seg_idx)
		{
			DPRINT_DBG(BLKVSC_DRV, "bio_for_each_segment() - req %p bio %p bvec %p seg_idx %d databuf_idx %d\n",
							req, bio, bvec, seg_idx, databuf_idx);

			// Get a new storvsc request
			if ( (!blkvsc_req) ||									// 1st-time
				 (databuf_idx >= MAX_MULTIPAGE_BUFFER_COUNT) ||
				 (bvec->bv_offset != 0) ||							// hole at the begin of page
				 (prev_bvec && (prev_bvec->bv_len != PAGE_SIZE)) )	// hold at the end of page
			{
				// submit the prev one
				if (blkvsc_req)
				{
					blkvsc_req->sector_start = start_sector;
					sector_div(blkvsc_req->sector_start, (blkdev->sector_size >> 9));

					blkvsc_req->sector_count = num_sectors / (blkdev->sector_size >> 9);

					blkvsc_init_rw(blkvsc_req);
				}

				// Create new blkvsc_req to represent the current bvec
				blkvsc_req = kmem_cache_alloc(blkdev->request_pool, GFP_ATOMIC);
				if (!blkvsc_req)
				{
					// free up everything
					list_for_each_entry_safe(blkvsc_req, tmp, &group->blkvsc_req_list, req_entry)
					{
						list_del(&blkvsc_req->req_entry);
						kmem_cache_free(blkdev->request_pool, blkvsc_req);
					}

					kmem_cache_free(blkdev->request_pool, group);
					return -ENOMEM;
				}

				memset(blkvsc_req, 0, sizeof(struct blkvsc_request));

				blkvsc_req->dev = blkdev;
				blkvsc_req->req = req;
				blkvsc_req->request.DataBuffer.Offset = bvec->bv_offset;
				blkvsc_req->request.DataBuffer.Length = 0;

				// Add to the group
				blkvsc_req->group = group;
				blkvsc_req->group->outstanding++;
				list_add_tail(&blkvsc_req->req_entry, &blkvsc_req->group->blkvsc_req_list);

				start_sector += num_sectors;
				num_sectors = 0;
				databuf_idx = 0;
			}

			// Add the curr bvec/segment to the curr blkvsc_req
			blkvsc_req->request.DataBuffer.PfnArray[databuf_idx] = page_to_pfn(bvec->bv_page);
			blkvsc_req->request.DataBuffer.Length += bvec->bv_len;

			prev_bvec = bvec;

			databuf_idx++;
			num_sectors += bvec->bv_len >> 9;

		} // bio_for_each_segment

	} // rq_for_each_bio

	// Handle the last one
	if (blkvsc_req)
	{
		DPRINT_DBG(BLKVSC_DRV, "blkdev %p req %p group %p count %d\n", blkdev, req, blkvsc_req->group, blkvsc_req->group->outstanding);

		blkvsc_req->sector_start = start_sector;
		sector_div(blkvsc_req->sector_start, (blkdev->sector_size >> 9));

		blkvsc_req->sector_count = num_sectors / (blkdev->sector_size >> 9);

		blkvsc_init_rw(blkvsc_req);
	}

	list_for_each_entry(blkvsc_req, &group->blkvsc_req_list, req_entry)
	{
		if (pending)
		{
			DPRINT_DBG(BLKVSC_DRV, "adding blkvsc_req to pending_list - blkvsc_req %p start_sect %llu sect_count %d (%llu %d)\n",
				blkvsc_req, blkvsc_req->sector_start, blkvsc_req->sector_count, start_sector, num_sectors);

			list_add_tail(&blkvsc_req->pend_entry, &blkdev->pending_list);
		}
		else
		{
			ret = blkvsc_submit_request(blkvsc_req, blkvsc_request_completion);
			if (ret == -1)
			{
				pending = 1;
				list_add_tail(&blkvsc_req->pend_entry, &blkdev->pending_list);
			}

			DPRINT_DBG(BLKVSC_DRV, "submitted blkvsc_req %p start_sect %llu sect_count %d (%llu %d) ret %d\n",
				blkvsc_req, blkvsc_req->sector_start, blkvsc_req->sector_count, start_sector, num_sectors, ret);
		}
	}

	return pending;
}

static void blkvsc_cmd_completion(STORVSC_REQUEST* request)
{
	struct blkvsc_request *blkvsc_req=(struct blkvsc_request*)request->Context;
	struct block_device_context *blkdev = (struct block_device_context*)blkvsc_req->dev;

	struct scsi_sense_hdr sense_hdr;

	DPRINT_DBG(BLKVSC_DRV, "blkvsc_cmd_completion() - req %p\n", blkvsc_req);

	blkdev->num_outstanding_reqs--;

	if (blkvsc_req->request.Status)
	{
		if (scsi_normalize_sense(blkvsc_req->sense_buffer, SCSI_SENSE_BUFFERSIZE, &sense_hdr))
		{
			scsi_print_sense_hdr("blkvsc", &sense_hdr);
		}
	}

	blkvsc_req->cond =1;
	wake_up_interruptible(&blkvsc_req->wevent);
}

static void blkvsc_request_completion(STORVSC_REQUEST* request)
{
	struct blkvsc_request *blkvsc_req=(struct blkvsc_request*)request->Context;
	struct block_device_context *blkdev = (struct block_device_context*)blkvsc_req->dev;
	unsigned long flags;
	struct blkvsc_request *comp_req, *tmp;

	ASSERT(blkvsc_req->group);

	DPRINT_DBG(BLKVSC_DRV, "blkdev %p blkvsc_req %p group %p type %s sect_start %llu sect_count %d len %d group outstd %d total outstd %d\n",
		blkdev,
		blkvsc_req,
		blkvsc_req->group,
		(blkvsc_req->write)?"WRITE":"READ",
		blkvsc_req->sector_start,
		blkvsc_req->sector_count,
		blkvsc_req->request.DataBuffer.Length,
		blkvsc_req->group->outstanding,
		blkdev->num_outstanding_reqs);

	spin_lock_irqsave(&blkdev->lock, flags);

	blkdev->num_outstanding_reqs--;
	blkvsc_req->group->outstanding--;

	// Only start processing when all the blkvsc_reqs are completed. This guarantees no out-of-order
	// blkvsc_req completion when calling end_that_request_first()
	if (blkvsc_req->group->outstanding == 0)
	{
		list_for_each_entry_safe(comp_req, tmp, &blkvsc_req->group->blkvsc_req_list, req_entry)
		{
			DPRINT_DBG(BLKVSC_DRV, "completing blkvsc_req %p sect_start %llu sect_count %d \n",
				comp_req,
				comp_req->sector_start,
				comp_req->sector_count);

			list_del(&comp_req->req_entry);

#ifdef KERNEL_2_6_27
			if (!__blk_end_request(
				comp_req->req,
				(!comp_req->request.Status ? 0: -EIO),
				comp_req->sector_count * blkdev->sector_size))
			{
				//All the sectors have been xferred ie the request is done
				DPRINT_DBG(BLKVSC_DRV, "req %p COMPLETED\n", comp_req->req);
				kmem_cache_free(blkdev->request_pool, comp_req->group);
			}
#else
			if (!end_that_request_first(comp_req->req, !comp_req->request.Status,  (comp_req->sector_count * (blkdev->sector_size >> 9))))
			{
				//All the sectors have been xferred ie the request is done
				DPRINT_DBG(BLKVSC_DRV, "req %p COMPLETED\n", comp_req->req);

				end_that_request_last(comp_req->req, !comp_req->request.Status);

				kmem_cache_free(blkdev->request_pool, comp_req->group);
			}
#endif

			kmem_cache_free(blkdev->request_pool, comp_req);
		}

		if (!blkdev->shutting_down)
		{
			blkvsc_do_pending_reqs(blkdev);
			blk_start_queue(blkdev->gd->queue);
			blkvsc_request(blkdev->gd->queue);
		}
	}

	spin_unlock_irqrestore(&blkdev->lock, flags);
}

static int blkvsc_cancel_pending_reqs(struct block_device_context *blkdev)
{
	struct blkvsc_request *pend_req, *tmp;
	struct blkvsc_request *comp_req, *tmp2;

	int ret=0;

	DPRINT_DBG(BLKVSC_DRV, "blkvsc_cancel_pending_reqs()");

	// Flush the pending list first
	list_for_each_entry_safe(pend_req, tmp, &blkdev->pending_list, pend_entry)
	{
		// The pend_req could be part of a partially completed request. If so, complete those req first
		// until we hit the pend_req
		list_for_each_entry_safe(comp_req, tmp2, &pend_req->group->blkvsc_req_list, req_entry)
		{
			DPRINT_DBG(BLKVSC_DRV, "completing blkvsc_req %p sect_start %llu sect_count %d \n",
				comp_req,
				comp_req->sector_start,
				comp_req->sector_count);

			if (comp_req == pend_req)
				break;

			list_del(&comp_req->req_entry);

			if (comp_req->req)
			{
#ifdef KERNEL_2_6_27
			ret = __blk_end_request(
			    comp_req->req,
			    (!comp_req->request.Status ? 0 : -EIO),
			    comp_req->sector_count * blkdev->sector_size);
#else
			ret = end_that_request_first(comp_req->req, !comp_req->request.Status,  (comp_req->sector_count * (blkdev->sector_size >> 9)));
#endif
			ASSERT(ret != 0);
			}

			kmem_cache_free(blkdev->request_pool, comp_req);
		}

		DPRINT_DBG(BLKVSC_DRV, "cancelling pending request - %p\n", pend_req);

		list_del(&pend_req->pend_entry);

		list_del(&pend_req->req_entry);

		if (comp_req->req)
		{
#ifdef KERNEL_2_6_27
		if (!__blk_end_request(
			pend_req->req,
			-EIO,
			pend_req->sector_count * blkdev->sector_size))
		{
			//All the sectors have been xferred ie the request is done
			DPRINT_DBG(BLKVSC_DRV, "blkvsc_cancel_pending_reqs() - req %p COMPLETED\n", pend_req->req);
			kmem_cache_free(blkdev->request_pool, pend_req->group);
		}
#else
		if (!end_that_request_first(pend_req->req, 0,  (pend_req->sector_count * (blkdev->sector_size >> 9))))
		{
			//All the sectors have been xferred ie the request is done
			DPRINT_DBG(BLKVSC_DRV, "blkvsc_cancel_pending_reqs() - req %p COMPLETED\n", pend_req->req);

			end_that_request_last(pend_req->req, 0);

			kmem_cache_free(blkdev->request_pool, pend_req->group);
		}
#endif
		}

		kmem_cache_free(blkdev->request_pool, pend_req);
	}

	return ret;
}

static int blkvsc_do_pending_reqs(struct block_device_context *blkdev)
{
	struct blkvsc_request *pend_req, *tmp;
	int ret=0;

	// Flush the pending list first
	list_for_each_entry_safe(pend_req, tmp, &blkdev->pending_list, pend_entry)
	{
		DPRINT_DBG(BLKVSC_DRV, "working off pending_list - %p\n", pend_req);

		ret = blkvsc_submit_request(pend_req, blkvsc_request_completion);
		if (ret != 0)
		{
			break;
		}
		else
		{
			list_del(&pend_req->pend_entry);
		}
	}

	return ret;
}

static void blkvsc_request(struct request_queue *queue)
{
	struct block_device_context *blkdev = NULL;
	struct request *req;
	int ret=0;

	DPRINT_DBG(BLKVSC_DRV, "- enter \n");
	while ((req = blk_peek_request(queue)) != NULL)
	{
		DPRINT_DBG(BLKVSC_DRV, "- req %p\n", req);

		blkdev = req->rq_disk->private_data;
		if (blkdev->shutting_down || !blk_fs_request(req) || blkdev->media_not_present) {
			__blk_end_request_cur(req, 0);
			continue;
		}

		ret = blkvsc_do_pending_reqs(blkdev);

		if (ret != 0)
		{
			DPRINT_DBG(BLKVSC_DRV, "- stop queue - pending_list not empty\n");
			blk_stop_queue(queue);
			break;
		}

		blk_start_request(req);

		ret = blkvsc_do_request(blkdev, req);
		if (ret > 0)
		{
			DPRINT_DBG(BLKVSC_DRV, "- stop queue - no room\n");
			blk_stop_queue(queue);
			break;
		}
		else if (ret < 0)
		{
			DPRINT_DBG(BLKVSC_DRV, "- stop queue - no mem\n");
			blk_requeue_request(queue, req);
			blk_stop_queue(queue);
			break;
		}
	}
}

static int blkvsc_open(struct inode *inode, struct file *filep)
{
	struct block_device_context *blkdev = inode->i_bdev->bd_disk->private_data;

	DPRINT_DBG(BLKVSC_DRV, "- users %d disk %s\n", blkdev->users, blkdev->gd->disk_name);

	spin_lock(&blkdev->lock);

	if (!blkdev->users && blkdev->device_type == DVD_TYPE)
	{
		spin_unlock(&blkdev->lock);
		check_disk_change(inode->i_bdev);
		spin_lock(&blkdev->lock);
	}

	blkdev->users++;

	spin_unlock(&blkdev->lock);
	return 0;
}

static int blkvsc_release(struct inode *inode, struct file *filep)
{
	struct block_device_context *blkdev = inode->i_bdev->bd_disk->private_data;

	DPRINT_DBG(BLKVSC_DRV, "- users %d disk %s\n", blkdev->users, blkdev->gd->disk_name);

	spin_lock(&blkdev->lock);
	if (blkdev->users == 1)
	{
		spin_unlock(&blkdev->lock);
		blkvsc_do_flush(blkdev);
		spin_lock(&blkdev->lock);
	}

	blkdev->users--;

	spin_unlock(&blkdev->lock);
	return 0;
}

static int blkvsc_media_changed(struct gendisk *gd)
{
	DPRINT_DBG(BLKVSC_DRV, "- enter\n");

	return 1;
}

static int blkvsc_revalidate_disk(struct gendisk *gd)
{
	struct block_device_context *blkdev = gd->private_data;

	DPRINT_DBG(BLKVSC_DRV, "- enter\n");

	if (blkdev->device_type == DVD_TYPE)
	{
		blkvsc_do_read_capacity(blkdev);
		set_capacity(blkdev->gd, blkdev->capacity * (blkdev->sector_size/512));
		blk_queue_logical_block_size(gd->queue, blkdev->sector_size);
	}
	return 0;
}

int blkvsc_getgeo(struct block_device *bd, struct hd_geometry *hg)
{
	sector_t total_sectors = get_capacity(bd->bd_disk);
	sector_t cylinder_times_heads=0;
	sector_t temp=0;

	int sectors_per_track=0;
	int heads=0;
	int cylinders=0;
	int rem=0;

    if (total_sectors > (65535 * 16 * 255)) {
        total_sectors = (65535 * 16 * 255);
    }

    if (total_sectors >= (65535 * 16 * 63)) {
        sectors_per_track = 255;
        heads = 16;

		cylinder_times_heads = total_sectors;
		rem = sector_div(cylinder_times_heads, sectors_per_track); // sector_div stores the quotient in cylinder_times_heads
    }
	else
	{
        sectors_per_track = 17;

		cylinder_times_heads = total_sectors;
        rem = sector_div(cylinder_times_heads, sectors_per_track); 	// sector_div stores the quotient in cylinder_times_heads

		temp = cylinder_times_heads + 1023;
		rem = sector_div(temp, 1024); 	// sector_div stores the quotient in temp

		heads = temp;

        if (heads < 4) {
            heads = 4;
        }

        if (cylinder_times_heads >= (heads * 1024) || (heads > 16)) {
            sectors_per_track = 31;
            heads = 16;

			cylinder_times_heads = total_sectors;
            rem = sector_div(cylinder_times_heads, sectors_per_track); // sector_div stores the quotient in cylinder_times_heads
        }

        if (cylinder_times_heads >= (heads * 1024)) {
            sectors_per_track = 63;
            heads = 16;

			cylinder_times_heads = total_sectors;
            rem = sector_div(cylinder_times_heads, sectors_per_track); // sector_div stores the quotient in cylinder_times_heads
        }
    }

	temp = cylinder_times_heads;
    rem = sector_div(temp, heads); // sector_div stores the quotient in temp
	cylinders = temp;

	hg->heads = heads;
    hg->sectors = sectors_per_track;
    hg->cylinders = cylinders;

	DPRINT_INFO(BLKVSC_DRV, "CHS (%d, %d, %d)", cylinders, heads, sectors_per_track);

    return 0;
}

static int blkvsc_ioctl(struct inode *inode, struct file *filep, unsigned cmd, unsigned long arg)
{
	struct block_device *bd = inode->i_bdev;
	struct block_device_context *blkdev = bd->bd_disk->private_data;
	int ret=0;

	switch (cmd)
	{
	// TODO: I think there is certain format for HDIO_GET_IDENTITY rather than just
	// a GUID. Commented it out for now.
	/*case HDIO_GET_IDENTITY:
		DPRINT_INFO(BLKVSC_DRV, "HDIO_GET_IDENTITY\n");

		if (copy_to_user((void __user *)arg, blkdev->device_id, blkdev->device_id_len))
		{
			ret = -EFAULT;
		}

		break;*/
	default:
		ret = -EINVAL;
		break;
	}

	return ret;
}


MODULE_LICENSE("GPL");

static int __init blkvsc_init(void)
{
	int ret;

	ASSERT(sizeof(sector_t) == 8); // Make sure CONFIG_LBD is set

	DPRINT_ENTER(BLKVSC_DRV);

	DPRINT_INFO(BLKVSC_DRV, "Blkvsc initializing....");

	ret = blkvsc_drv_init(BlkVscInitialize);

	DPRINT_EXIT(BLKVSC_DRV);

	return ret;
}

static void __exit blkvsc_exit(void)
{
	DPRINT_ENTER(BLKVSC_DRV);

	blkvsc_drv_exit();

	DPRINT_ENTER(BLKVSC_DRV);
}

module_param(blkvsc_ringbuffer_size, int, S_IRUGO);

module_init(blkvsc_init);
module_exit(blkvsc_exit);

// eof