Staging: hv: add the Hyper-V virtual block driver

This is the virtual block driver when running Linux on top of Hyper-V.

Signed-off-by: Hank Janssen <hjanssen@microsoft.com>
Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 1547 insertions, 0 deletions

diff --git a/drivers/staging/hv/blkvsc_drv.c b/drivers/staging/hv/blkvsc_drv.c
new file mode 100644
index 0000000..2f67981
--- /dev/null
+++ b/drivers/staging/hv/blkvsc_drv.c
@@ -0,0 +1,1547 @@
+/*
+ *
+ * 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>
+ *
+ */
+
+
+#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 "logging.h"
+#include "vmbus.h"
+
+#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(device_ctx->device.bus_id,
+                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
+
+	device->driver_data = 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_hardsect_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 = (struct block_device_context*)device->driver_data;
+	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 = (struct block_device_context*)device->driver_data;
+	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, req->sector);
+
+	// 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 = req->sector;
+
+	// 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 = elv_next_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) {
+			end_request(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;
+		}
+
+		blkdev_dequeue_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_hardsect_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