drivers/staging/hv/storvsc_drv.c

/*
 *
 * 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:
 *   Haiyang Zhang <haiyangz@microsoft.com>
 *   Hank Janssen  <hjanssen@microsoft.com>
 *
 */

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

#include <scsi/scsi.h>
#include <scsi/scsi_cmnd.h>
#include <scsi/scsi_host.h>
#include <scsi/scsi_device.h>
#include <scsi/scsi_tcq.h>
#include <scsi/scsi_eh.h>
#include <scsi/scsi_devinfo.h>

#include <scsi/scsi_dbg.h>

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

#include "include/StorVscApi.h"


/* #defines */



/* Data types */

struct host_device_context {
    struct work_struct		host_rescan_work;  /* must be 1st field */
    struct device_context	*device_ctx; /* point back to our device context */
    struct kmem_cache               *request_pool;
    unsigned int			port;
    unsigned char			path;
    unsigned char			target;
};

struct storvsc_cmd_request {
	struct list_head	entry;
	struct scsi_cmnd	*cmd;

	unsigned int bounce_sgl_count;
	struct scatterlist	*bounce_sgl;

	struct hv_storvsc_request request;
	/* !!!DO NOT ADD ANYTHING BELOW HERE!!! */
	/* The extension buffer falls right here and is pointed to by request.Extension; */
};

struct storvsc_driver_context {
	/* !! These must be the first 2 fields !! */
	struct driver_context	drv_ctx;
	STORVSC_DRIVER_OBJECT	drv_obj;
};

/* Static decl */
static int storvsc_probe(struct device *dev);
static int storvsc_queuecommand(struct scsi_cmnd *scmnd, void (*done)(struct scsi_cmnd *));
static int storvsc_device_alloc(struct scsi_device *);
static int storvsc_device_configure(struct scsi_device *);
static int storvsc_host_reset_handler(struct scsi_cmnd *scmnd);
static void storvsc_host_rescan_callback(struct work_struct *work);
static void storvsc_host_rescan(struct hv_device* device_obj);
static int storvsc_remove(struct device *dev);

static struct scatterlist *create_bounce_buffer(struct scatterlist *sgl, unsigned int sg_count, unsigned int len);
static void destroy_bounce_buffer(struct scatterlist *sgl, unsigned int sg_count);
static int do_bounce_buffer(struct scatterlist *sgl, unsigned int sg_count);
static unsigned int copy_from_bounce_buffer(struct scatterlist *orig_sgl, struct scatterlist *bounce_sgl, unsigned int orig_sgl_count);
static unsigned int copy_to_bounce_buffer(struct scatterlist *orig_sgl, struct scatterlist *bounce_sgl, unsigned int orig_sgl_count);

static int storvsc_report_luns(struct scsi_device *sdev, unsigned int luns[], unsigned int *lun_count);
static int storvsc_get_chs(struct scsi_device *sdev, struct block_device * bdev, sector_t capacity, int *info);


static int storvsc_ringbuffer_size = STORVSC_RING_BUFFER_SIZE;

/* The one and only one */
static struct storvsc_driver_context g_storvsc_drv;

/* Scsi driver */
static struct scsi_host_template scsi_driver = {
	.module						= THIS_MODULE,
	.name						= "storvsc_host_t",
	.bios_param					= storvsc_get_chs,
	.queuecommand				= storvsc_queuecommand,
	.eh_host_reset_handler		= storvsc_host_reset_handler,
	.slave_alloc				= storvsc_device_alloc,
	.slave_configure			= storvsc_device_configure,
	.cmd_per_lun				= 1,
	.can_queue					= STORVSC_MAX_IO_REQUESTS*STORVSC_MAX_TARGETS, /* 64 max_queue * 1 target */
	.this_id					= -1,
	/* no use setting to 0 since ll_blk_rw reset it to 1 */
	.sg_tablesize				= MAX_MULTIPAGE_BUFFER_COUNT,/* currently 32 */
	/* ENABLE_CLUSTERING allows mutiple physically contig bio_vecs to merge into 1 sg element. If set, we must */
	/* limit the max_segment_size to PAGE_SIZE, otherwise we may get 1 sg element that represents multiple */
	/* physically contig pfns (ie sg[x].length > PAGE_SIZE). */
	.use_clustering				= ENABLE_CLUSTERING,
	/* Make sure we dont get a sg segment crosses a page boundary */
	.dma_boundary				= PAGE_SIZE-1,
};


/*++

Name:	storvsc_drv_init()

Desc:	StorVsc driver initialization.

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

	DPRINT_ENTER(STORVSC_DRV);

	vmbus_get_interface(&storvsc_drv_obj->Base.VmbusChannelInterface);

	storvsc_drv_obj->RingBufferSize = storvsc_ringbuffer_size;
	storvsc_drv_obj->OnHostRescan = storvsc_host_rescan;

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

	DPRINT_INFO(STORVSC_DRV, "request extension size %u, max outstanding reqs %u", storvsc_drv_obj->RequestExtSize, storvsc_drv_obj->MaxOutstandingRequestsPerChannel);

	if (storvsc_drv_obj->MaxOutstandingRequestsPerChannel < STORVSC_MAX_IO_REQUESTS)
	{
		DPRINT_ERR(STORVSC_DRV, "The number of outstanding io requests (%d) is larger than that supported (%d) internally.",
			STORVSC_MAX_IO_REQUESTS, storvsc_drv_obj->MaxOutstandingRequestsPerChannel);
		return -1;
	}

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

	drv_ctx->probe = storvsc_probe;
	drv_ctx->remove = storvsc_remove;

	/* The driver belongs to vmbus */
	ret = vmbus_child_driver_register(drv_ctx);

	DPRINT_EXIT(STORVSC_DRV);

	return ret;
}


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

/*++

Name:	storvsc_drv_exit()

Desc:

--*/
static void storvsc_drv_exit(void)
{
	STORVSC_DRIVER_OBJECT *storvsc_drv_obj=&g_storvsc_drv.drv_obj;
	struct driver_context *drv_ctx=&g_storvsc_drv.drv_ctx;
	struct device *current_dev=NULL;
	int ret;

	DPRINT_ENTER(STORVSC_DRV);

	while (1)
	{
		current_dev = NULL;

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

		if (ret)
			DPRINT_WARN(STORVSC_DRV,
				    "driver_for_each_device returned %d", ret);

		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(STORVSC_DRV);

	return;
}

/*++

Name:	storvsc_probe()

Desc:	Add a new device for this driver

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

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

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

	struct Scsi_Host *host;
	struct host_device_context *host_device_ctx;
	STORVSC_DEVICE_INFO device_info;

	DPRINT_ENTER(STORVSC_DRV);

	if (!storvsc_drv_obj->Base.OnDeviceAdd)
		return -1;

	host = scsi_host_alloc(&scsi_driver, sizeof(struct host_device_context));
	if (!host)
	{
		DPRINT_ERR(STORVSC_DRV, "unable to allocate scsi host object");
		return -ENOMEM;
	}

	dev_set_drvdata(device, host);

	host_device_ctx = (struct host_device_context*)host->hostdata;
	memset(host_device_ctx, 0, sizeof(struct host_device_context));

	host_device_ctx->port = host->host_no;
	host_device_ctx->device_ctx = device_ctx;

	INIT_WORK(&host_device_ctx->host_rescan_work, storvsc_host_rescan_callback);

	host_device_ctx->request_pool =
	    kmem_cache_create
	    (dev_name(&device_ctx->device),
	     sizeof(struct storvsc_cmd_request) + storvsc_drv_obj->RequestExtSize,
	     0,
	     SLAB_HWCACHE_ALIGN, NULL);

	if (!host_device_ctx->request_pool)
	{
		scsi_host_put(host);
		DPRINT_EXIT(STORVSC_DRV);

		return -ENOMEM;
	}

	device_info.PortNumber = host->host_no;
	/* Call to the vsc driver to add the device */
	ret = storvsc_drv_obj->Base.OnDeviceAdd(device_obj, (void*)&device_info);
	if (ret != 0)
	{
		DPRINT_ERR(STORVSC_DRV, "unable to add scsi vsc device");
		kmem_cache_destroy(host_device_ctx->request_pool);
		scsi_host_put(host);
		DPRINT_EXIT(STORVSC_DRV);

		return -1;
	}

	/* host_device_ctx->port = device_info.PortNumber; */
	host_device_ctx->path = device_info.PathId;
	host_device_ctx->target = device_info.TargetId;

	host->max_lun = STORVSC_MAX_LUNS_PER_TARGET;	/* max # of devices per target */
	host->max_id = STORVSC_MAX_TARGETS;			/* max # of targets per channel */
	host->max_channel = STORVSC_MAX_CHANNELS -1;	/* max # of channels */

	/* Register the HBA and start the scsi bus scan */
	ret = scsi_add_host(host, device);
	if (ret != 0)
	{
		DPRINT_ERR(STORVSC_DRV, "unable to add scsi host device");

		storvsc_drv_obj->Base.OnDeviceRemove(device_obj);

		kmem_cache_destroy(host_device_ctx->request_pool);
		scsi_host_put(host);
		DPRINT_EXIT(STORVSC_DRV);

		return -1;
	}

	scsi_scan_host(host);

	DPRINT_EXIT(STORVSC_DRV);

	return ret;
}


/*++

Name:	storvsc_remove()

Desc:	Callback when our device is removed

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

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

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

	struct Scsi_Host *host = dev_get_drvdata(device);
	struct host_device_context *host_device_ctx=(struct host_device_context*)host->hostdata;


	DPRINT_ENTER(STORVSC_DRV);

	if (!storvsc_drv_obj->Base.OnDeviceRemove)
	{
		DPRINT_EXIT(STORVSC_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(STORVSC, "unable to remove vsc device (ret %d)", ret);
	}

	if (host_device_ctx->request_pool)
	{
		kmem_cache_destroy(host_device_ctx->request_pool);
		host_device_ctx->request_pool = NULL;
	}

	DPRINT_INFO(STORVSC, "removing host adapter (%p)...", host);
	scsi_remove_host(host);

	DPRINT_INFO(STORVSC, "releasing host adapter (%p)...", host);
	scsi_host_put(host);

	DPRINT_EXIT(STORVSC_DRV);

	return ret;
}

/*++

Name:	storvsc_commmand_completion()

Desc:	Command completion processing

--*/
static void storvsc_commmand_completion(struct hv_storvsc_request *request)
{
	struct storvsc_cmd_request *cmd_request = (struct storvsc_cmd_request*)request->Context;
	struct scsi_cmnd *scmnd = cmd_request->cmd;
	struct host_device_context *host_device_ctx = (struct host_device_context*)scmnd->device->host->hostdata;
	void (*scsi_done_fn)(struct scsi_cmnd *);
	struct scsi_sense_hdr sense_hdr;

	ASSERT(request == &cmd_request->request);
	ASSERT((unsigned long)scmnd->host_scribble == (unsigned long)cmd_request);
	ASSERT(scmnd);
	ASSERT(scmnd->scsi_done);

	DPRINT_ENTER(STORVSC_DRV);

	if (cmd_request->bounce_sgl_count)/* using bounce buffer */
	{
		/* printk("copy_from_bounce_buffer\n"); */

		/* FIXME: We can optimize on writes by just skipping this */
		copy_from_bounce_buffer(scsi_sglist(scmnd), cmd_request->bounce_sgl, scsi_sg_count(scmnd));
		destroy_bounce_buffer(cmd_request->bounce_sgl, cmd_request->bounce_sgl_count);
	}

	scmnd->result = request->Status;

	if (scmnd->result)
	{
		if (scsi_normalize_sense(scmnd->sense_buffer, request->SenseBufferSize, &sense_hdr))
		{
			scsi_print_sense_hdr("storvsc", &sense_hdr);
		}
	}

	ASSERT(request->BytesXfer <= request->DataBuffer.Length);
	scsi_set_resid(scmnd, request->DataBuffer.Length - request->BytesXfer);

	scsi_done_fn = scmnd->scsi_done;

	scmnd->host_scribble = NULL;
	scmnd->scsi_done = NULL;

	/* !!DO NOT MODIFY the scmnd after this call */
	scsi_done_fn(scmnd);

	kmem_cache_free(host_device_ctx->request_pool, cmd_request);

	DPRINT_EXIT(STORVSC_DRV);
}

static int do_bounce_buffer(struct scatterlist *sgl, unsigned int sg_count)
{
	int i=0;

	/* No need to check */
	if (sg_count < 2)
		return -1;

	/* We have at least 2 sg entries */
	for ( i=0; i<sg_count; i++ )
	{
		if (i == 0) /* make sure 1st one does not have hole */
		{
			if (sgl[i].offset + sgl[i].length != PAGE_SIZE)
				return i;
		}
		else if (i == sg_count - 1) /* make sure last one does not have hole */
		{
			if (sgl[i].offset != 0)
				return i;
		}
		else /* make sure no hole in the middle */
		{
			if (sgl[i].length != PAGE_SIZE || sgl[i].offset != 0)
			{
				return i;
			}
		}
	}
	return -1;
}

static struct scatterlist *create_bounce_buffer(struct scatterlist *sgl, unsigned int sg_count, unsigned int len)
{
	int i;
	int num_pages=0;
	struct scatterlist* bounce_sgl;
	struct page *page_buf;

	num_pages = ALIGN_UP(len, PAGE_SIZE) >> PAGE_SHIFT;

	bounce_sgl = kcalloc(num_pages, sizeof(struct scatterlist), GFP_ATOMIC);
	if (!bounce_sgl)
	{
		return NULL;
	}

	for(i=0; i<num_pages; i++)
	{
		page_buf = alloc_page(GFP_ATOMIC);
		if (!page_buf)
		{
			goto cleanup;
		}
		sg_set_page(&bounce_sgl[i], page_buf, 0, 0);
	}

	return bounce_sgl;

cleanup:
	destroy_bounce_buffer(bounce_sgl, num_pages);
	return NULL;
}

static void destroy_bounce_buffer(struct scatterlist *sgl, unsigned int sg_count)
{
	int i;
	struct page *page_buf;

	for (i=0; i<sg_count; i++)
	{
		if ((page_buf = sg_page((&sgl[i]))) != NULL)

		{
			__free_page(page_buf);
		}
	}

	kfree(sgl);
}

/* Assume the bounce_sgl has enough room ie using the create_bounce_buffer() */
static unsigned int copy_to_bounce_buffer(struct scatterlist *orig_sgl, struct scatterlist *bounce_sgl, unsigned int orig_sgl_count)
{
	int i=0,j=0;
	unsigned long src, dest;
	unsigned int srclen, destlen, copylen;
	unsigned int total_copied=0;
	unsigned long bounce_addr=0;
	unsigned long src_addr=0;
	unsigned long flags;

	local_irq_save(flags);

	for (i=0; i<orig_sgl_count; i++)
	{
		src_addr = (unsigned long)kmap_atomic(sg_page((&orig_sgl[i])), KM_IRQ0) + orig_sgl[i].offset;
		src = src_addr;
		srclen = orig_sgl[i].length;

		/* if (PageHighMem(orig_sgl[i].page)) */
		/* printk("HighMem page detected - addr %p", (void*)src); */

		ASSERT(orig_sgl[i].offset + orig_sgl[i].length <= PAGE_SIZE);

		if (j == 0)
		{
			bounce_addr = (unsigned long)kmap_atomic(sg_page((&bounce_sgl[j])), KM_IRQ0);
		}

		while (srclen)
		{
			/* assume bounce offset always == 0 */
			dest = bounce_addr + bounce_sgl[j].length;
			destlen = PAGE_SIZE - bounce_sgl[j].length;

			copylen = min(srclen, destlen);
			memcpy((void*)dest, (void*)src, copylen);

			total_copied += copylen;
			bounce_sgl[j].length += copylen;
			srclen -= copylen;
			src += copylen;

			if (bounce_sgl[j].length == PAGE_SIZE) /* full..move to next entry */
			{
				kunmap_atomic((void*)bounce_addr, KM_IRQ0);
				j++;

				/* if we need to use another bounce buffer */
				if (srclen || i != orig_sgl_count -1)
				{
					bounce_addr = (unsigned long)kmap_atomic(sg_page((&bounce_sgl[j])), KM_IRQ0);
				}
			}
			else if (srclen == 0 && i == orig_sgl_count -1) /* unmap the last bounce that is < PAGE_SIZE */
			{
				kunmap_atomic((void*)bounce_addr, KM_IRQ0);
			}
		}

		kunmap_atomic((void*)(src_addr - orig_sgl[i].offset), KM_IRQ0);
	}

	local_irq_restore(flags);

	return total_copied;
}

/* Assume the original sgl has enough room */
static unsigned int copy_from_bounce_buffer(struct scatterlist *orig_sgl, struct scatterlist *bounce_sgl, unsigned int orig_sgl_count)
{
	int i=0,j=0;
	unsigned long src, dest;
	unsigned int srclen, destlen, copylen;
	unsigned int total_copied=0;
	unsigned long bounce_addr=0;
	unsigned long dest_addr=0;
	unsigned long flags;

	local_irq_save(flags);

	for (i=0; i<orig_sgl_count; i++)
	{
		dest_addr = (unsigned long)kmap_atomic(sg_page((&orig_sgl[i])), KM_IRQ0) + orig_sgl[i].offset;
		dest = dest_addr;
		destlen = orig_sgl[i].length;
		ASSERT(orig_sgl[i].offset + orig_sgl[i].length <= PAGE_SIZE);

		if (j == 0)
		{
			bounce_addr = (unsigned long)kmap_atomic(sg_page((&bounce_sgl[j])), KM_IRQ0);
		}

		while (destlen)
		{
			src = bounce_addr + bounce_sgl[j].offset;
			srclen = bounce_sgl[j].length - bounce_sgl[j].offset;

			copylen = min(srclen, destlen);
			memcpy((void*)dest, (void*)src, copylen);

			total_copied += copylen;
			bounce_sgl[j].offset += copylen;
			destlen -= copylen;
			dest += copylen;

			if (bounce_sgl[j].offset == bounce_sgl[j].length) /* full */
			{
				kunmap_atomic((void*)bounce_addr, KM_IRQ0);
				j++;

				/* if we need to use another bounce buffer */
				if (destlen || i != orig_sgl_count -1)
				{
					bounce_addr = (unsigned long)kmap_atomic(sg_page((&bounce_sgl[j])), KM_IRQ0);
				}
			}
			else if (destlen == 0 && i == orig_sgl_count -1) /* unmap the last bounce that is < PAGE_SIZE */
			{
				kunmap_atomic((void*)bounce_addr, KM_IRQ0);
			}
		}

		kunmap_atomic((void*)(dest_addr - orig_sgl[i].offset), KM_IRQ0);
	}

	local_irq_restore(flags);

	return total_copied;
}


/*++

Name:	storvsc_queuecommand()

Desc:	Initiate command processing

--*/
static int storvsc_queuecommand(struct scsi_cmnd *scmnd, void (*done)(struct scsi_cmnd *))
{
	int ret=0;
	struct host_device_context *host_device_ctx = (struct host_device_context*)scmnd->device->host->hostdata;
	struct device_context *device_ctx=host_device_ctx->device_ctx;
	struct driver_context *driver_ctx = driver_to_driver_context(device_ctx->device.driver);
	struct storvsc_driver_context *storvsc_drv_ctx = (struct storvsc_driver_context*)driver_ctx;
	STORVSC_DRIVER_OBJECT* storvsc_drv_obj = &storvsc_drv_ctx->drv_obj;

	struct hv_storvsc_request *request;
	struct storvsc_cmd_request *cmd_request;
	unsigned int request_size=0;
	int i;
	struct scatterlist *sgl;

	DPRINT_ENTER(STORVSC_DRV);

	DPRINT_DBG(STORVSC_DRV, "scmnd %p dir %d, use_sg %d buf %p len %d queue depth %d tagged %d",
		scmnd,
		scmnd->sc_data_direction,
		scsi_sg_count(scmnd),
		scsi_sglist(scmnd),
		scsi_bufflen(scmnd),
		scmnd->device->queue_depth,
		scmnd->device->tagged_supported);

	/* If retrying, no need to prep the cmd */
	if (scmnd->host_scribble)
	{
		ASSERT(scmnd->scsi_done != NULL);

		cmd_request = (struct storvsc_cmd_request* )scmnd->host_scribble;
		DPRINT_INFO(STORVSC_DRV, "retrying scmnd %p cmd_request %p", scmnd, cmd_request);

		goto retry_request;
	}

	ASSERT(scmnd->scsi_done == NULL);
	ASSERT(scmnd->host_scribble == NULL);

	scmnd->scsi_done = done;

	request_size = sizeof(struct storvsc_cmd_request);

	cmd_request = kmem_cache_alloc(host_device_ctx->request_pool, GFP_ATOMIC);
	if (!cmd_request)
	{
		DPRINT_ERR(STORVSC_DRV, "scmnd (%p) - unable to allocate storvsc_cmd_request...marking queue busy", scmnd);

		scmnd->scsi_done = NULL;
		return SCSI_MLQUEUE_DEVICE_BUSY;
	}

	/* Setup the cmd request */
	cmd_request->bounce_sgl_count = 0;
	cmd_request->bounce_sgl = NULL;
	cmd_request->cmd = scmnd;

	scmnd->host_scribble = (unsigned char*)cmd_request;

	request = &cmd_request->request;

	request->Extension = (void*)((unsigned long)cmd_request + request_size);
	DPRINT_DBG(STORVSC_DRV, "req %p size %d ext %d", request, request_size, storvsc_drv_obj->RequestExtSize);

	/* Build the SRB */
	switch(scmnd->sc_data_direction)
	{
	case DMA_TO_DEVICE:
		request->Type = WRITE_TYPE;
		break;
	case DMA_FROM_DEVICE:
		request->Type = READ_TYPE;
		break;
	default:
		request->Type = UNKNOWN_TYPE;
		break;
	}

	request->OnIOCompletion = storvsc_commmand_completion;
	request->Context = cmd_request;/* scmnd; */

	/* request->PortId = scmnd->device->channel; */
	request->Host = host_device_ctx->port;
	request->Bus = scmnd->device->channel;
	request->TargetId = scmnd->device->id;
	request->LunId = scmnd->device->lun;

	ASSERT(scmnd->cmd_len <= 16);
	request->CdbLen = scmnd->cmd_len;
	request->Cdb = scmnd->cmnd;

	request->SenseBuffer = scmnd->sense_buffer;
	request->SenseBufferSize = SCSI_SENSE_BUFFERSIZE;


	request->DataBuffer.Length = scsi_bufflen(scmnd);
	if (scsi_sg_count(scmnd))
	{
		sgl = (struct scatterlist*)scsi_sglist(scmnd);

		/* check if we need to bounce the sgl */
		if (do_bounce_buffer(sgl, scsi_sg_count(scmnd)) != -1)
		{
			DPRINT_INFO(STORVSC_DRV, "need to bounce buffer for this scmnd %p", scmnd);
			cmd_request->bounce_sgl = create_bounce_buffer(sgl, scsi_sg_count(scmnd), scsi_bufflen(scmnd));
			if (!cmd_request->bounce_sgl)
			{
				DPRINT_ERR(STORVSC_DRV, "unable to create bounce buffer for this scmnd %p", scmnd);

				scmnd->scsi_done = NULL;
				scmnd->host_scribble = NULL;
				kmem_cache_free(host_device_ctx->request_pool, cmd_request);

				return SCSI_MLQUEUE_HOST_BUSY;
			}

			cmd_request->bounce_sgl_count = ALIGN_UP(scsi_bufflen(scmnd), PAGE_SIZE) >> PAGE_SHIFT;

			/* printk("bouncing buffer allocated %p original buffer %p\n", bounce_sgl, sgl); */
			/* printk("copy_to_bounce_buffer\n"); */
			/* FIXME: We can optimize on reads by just skipping this */
			copy_to_bounce_buffer(sgl, cmd_request->bounce_sgl, scsi_sg_count(scmnd));

			sgl = cmd_request->bounce_sgl;
		}

		request->DataBuffer.Offset = sgl[0].offset;

		for (i = 0; i < scsi_sg_count(scmnd); i++ )
		{
			DPRINT_DBG(STORVSC_DRV, "sgl[%d] len %d offset %d \n", i, sgl[i].length, sgl[i].offset);
			request->DataBuffer.PfnArray[i] = page_to_pfn(sg_page((&sgl[i])));
		}
	}

	else if (scsi_sglist(scmnd))
	{
		ASSERT(scsi_bufflen(scmnd) <= PAGE_SIZE);
		request->DataBuffer.Offset = virt_to_phys(scsi_sglist(scmnd)) & (PAGE_SIZE-1);
		request->DataBuffer.PfnArray[0] = virt_to_phys(scsi_sglist(scmnd)) >> PAGE_SHIFT;
	}
	else
	{
		ASSERT(scsi_bufflen(scmnd) == 0);
	}

retry_request:

	/* Invokes the vsc to start an IO */
	ret = storvsc_drv_obj->OnIORequest(&device_ctx->device_obj, &cmd_request->request);
	if (ret == -1) /* no more space */
	{
		DPRINT_ERR(STORVSC_DRV, "scmnd (%p) - queue FULL...marking queue busy", scmnd);

		if (cmd_request->bounce_sgl_count)
		{
			/* FIXME: We can optimize on writes by just skipping this */
			copy_from_bounce_buffer(scsi_sglist(scmnd), cmd_request->bounce_sgl, scsi_sg_count(scmnd));
			destroy_bounce_buffer(cmd_request->bounce_sgl, cmd_request->bounce_sgl_count);
		}

		kmem_cache_free(host_device_ctx->request_pool, cmd_request);

		scmnd->scsi_done = NULL;
		scmnd->host_scribble = NULL;

		ret = SCSI_MLQUEUE_DEVICE_BUSY;
	}

	DPRINT_EXIT(STORVSC_DRV);

	return ret;
}

static int storvsc_merge_bvec(struct request_queue *q, struct bvec_merge_data *bmd, struct bio_vec *bvec)
{
	return bvec->bv_len; /* checking done by caller. */
}

/*++

Name:	storvsc_device_configure()

Desc:	Configure the specified scsi device

--*/
static int storvsc_device_alloc(struct scsi_device *sdevice)
{
	DPRINT_DBG(STORVSC_DRV, "sdev (%p) - setting device flag to %d", sdevice, BLIST_SPARSELUN);
	/* This enables luns to be located sparsely. Otherwise, we may not discovered them. */
	sdevice->sdev_bflags |= BLIST_SPARSELUN | BLIST_LARGELUN;
	return 0;
}

static int storvsc_device_configure(struct scsi_device *sdevice)
{
	DPRINT_INFO(STORVSC_DRV, "sdev (%p) - curr queue depth %d", sdevice, sdevice->queue_depth);

	DPRINT_INFO(STORVSC_DRV, "sdev (%p) - setting queue depth to %d", sdevice, STORVSC_MAX_IO_REQUESTS);
	scsi_adjust_queue_depth(sdevice, MSG_SIMPLE_TAG, STORVSC_MAX_IO_REQUESTS);

	DPRINT_INFO(STORVSC_DRV, "sdev (%p) - setting max segment size to %ld", sdevice, PAGE_SIZE);
	blk_queue_max_segment_size(sdevice->request_queue, PAGE_SIZE);

	DPRINT_INFO(STORVSC_DRV, "sdev (%p) - adding merge bio vec routine", sdevice);
	blk_queue_merge_bvec(sdevice->request_queue, storvsc_merge_bvec);

	blk_queue_bounce_limit(sdevice->request_queue, BLK_BOUNCE_ANY);
	/* sdevice->timeout = (2000 * HZ);//(75 * HZ); */

	return 0;
}

/*++

Name:	storvsc_host_reset_handler()

Desc:	Reset the scsi HBA

--*/
static int storvsc_host_reset_handler(struct scsi_cmnd *scmnd)
{
	int ret=SUCCESS;
	struct host_device_context *host_device_ctx = (struct host_device_context*)scmnd->device->host->hostdata;
	struct device_context *device_ctx = host_device_ctx->device_ctx;
	struct driver_context *driver_ctx = driver_to_driver_context(device_ctx->device.driver);
	struct storvsc_driver_context *storvsc_drv_ctx = (struct storvsc_driver_context*)driver_ctx;

	STORVSC_DRIVER_OBJECT *storvsc_drv_obj = &storvsc_drv_ctx->drv_obj;

	DPRINT_ENTER(STORVSC_DRV);

	DPRINT_INFO(STORVSC_DRV, "sdev (%p) dev obj (%p) - host resetting...", scmnd->device, &device_ctx->device_obj);

	/* Invokes the vsc to reset the host/bus */
	ASSERT(storvsc_drv_obj->OnHostReset);
	ret = storvsc_drv_obj->OnHostReset(&device_ctx->device_obj);
	if (ret != 0)
	{
		DPRINT_EXIT(STORVSC_DRV);
		return ret;
	}

	DPRINT_INFO(STORVSC_DRV, "sdev (%p) dev obj (%p) - host reseted", scmnd->device, &device_ctx->device_obj);

	DPRINT_EXIT(STORVSC_DRV);

	return ret;
}

/*++

Name:	storvsc_host_rescan

Desc:	Rescan the scsi HBA

--*/
static void storvsc_host_rescan_callback(struct work_struct *work)
{
	struct hv_device *device_obj =
	    &((struct host_device_context*)work)->device_ctx->device_obj;
	struct device_context* device_ctx = to_device_context(device_obj);
	struct Scsi_Host *host = dev_get_drvdata(&device_ctx->device);
	struct scsi_device *sdev;
	struct host_device_context *host_device_ctx;
	struct scsi_device **sdevs_remove_list;
	unsigned int sdevs_count=0;
	unsigned int found;
	unsigned int i;
	unsigned int lun_count=0;
	unsigned int *lun_list;

	DPRINT_ENTER(STORVSC_DRV);

	host_device_ctx = (struct host_device_context*)host->hostdata;
	lun_list = kcalloc(STORVSC_MAX_LUNS_PER_TARGET, sizeof(unsigned int), GFP_ATOMIC);
	if (!lun_list)
	{
		DPRINT_ERR(STORVSC_DRV, "unable to allocate lun list");
		return;
	}

	sdevs_remove_list = kcalloc(STORVSC_MAX_LUNS_PER_TARGET, sizeof(void *), GFP_ATOMIC);
	if (!sdevs_remove_list)
	{
		kfree(lun_list);
		DPRINT_ERR(STORVSC_DRV, "unable to allocate lun remove list");
		return;
	}

	DPRINT_INFO(STORVSC_DRV, "rescanning host for new scsi devices...");

	/* Rescan for new device */
	scsi_scan_target(&host->shost_gendev, host_device_ctx->path, host_device_ctx->target, SCAN_WILD_CARD, 1);

	DPRINT_INFO(STORVSC_DRV, "rescanning host for removed scsi device...");

	/* Use the 1st device to send the report luns cmd */
	shost_for_each_device(sdev, host)
	{
		lun_count=STORVSC_MAX_LUNS_PER_TARGET;
		storvsc_report_luns(sdev, lun_list, &lun_count);

		DPRINT_INFO(STORVSC_DRV, "report luns on scsi device (%p) found %u luns ", sdev, lun_count);
		DPRINT_INFO(STORVSC_DRV, "existing luns on scsi device (%p) host (%d)", sdev, host->host_no);

		scsi_device_put(sdev);
		break;
	}

	for (i=0; i<lun_count; i++)
	{
		DPRINT_INFO(STORVSC_DRV, "%d) lun %u", i, lun_list[i]);
	}

	/* Rescan for devices that may have been removed. */
	/* We do not have to worry that new devices may have been added since */
	/* this callback is serialized by the workqueue ie add/remove are done here. */
	shost_for_each_device(sdev, host)
	{
		/* See if this device is still here */
		found = 0;
		for (i=0; i<lun_count; i++)
		{
			if (sdev->lun == lun_list[i])
			{
				found = 1;
				break;
			}
		}
		if (!found)
		{
			DPRINT_INFO(STORVSC_DRV, "lun (%u) does not exists", sdev->lun);
			sdevs_remove_list[sdevs_count++] = sdev;
		}
	}

	/* Now remove the devices */
	for (i=0; i< sdevs_count; i++)
	{
		DPRINT_INFO(STORVSC_DRV, "removing scsi device (%p) lun (%u)...",
					sdevs_remove_list[i], sdevs_remove_list[i]->lun);

		/* make sure it is not removed from underneath us */
		if (!scsi_device_get(sdevs_remove_list[i]))
		{
			scsi_remove_device(sdevs_remove_list[i]);
			scsi_device_put(sdevs_remove_list[i]);
		}
	}

	DPRINT_INFO(STORVSC_DRV, "rescan completed on dev obj (%p) target (%u) bus (%u)", device_obj, host_device_ctx->target, host_device_ctx->path);

	kfree(lun_list);
	kfree(sdevs_remove_list);

	DPRINT_EXIT(STORVSC_DRV);
}

static int storvsc_report_luns(struct scsi_device *sdev, unsigned int luns[], unsigned int *lun_count)
{
	int i,j;
	unsigned int lun=0;
	unsigned int num_luns;
	int result;
	unsigned char *data;
	struct scsi_sense_hdr sshdr;
	unsigned char cmd[16]={0};
	unsigned int report_len = 8*(STORVSC_MAX_LUNS_PER_TARGET+1); /* Add 1 to cover the report_lun header */
	unsigned long long *report_luns;
	const unsigned int in_lun_count = *lun_count;

	*lun_count = 0;

	report_luns = kzalloc(report_len, GFP_ATOMIC);
	if (!report_luns)
	{
		return -ENOMEM;
	}

	cmd[0] = REPORT_LUNS;

	/* cmd length */
	*(unsigned int*)&cmd[6] = cpu_to_be32(report_len);

	result = scsi_execute_req(sdev, cmd, DMA_FROM_DEVICE, (unsigned char*)report_luns, report_len, &sshdr, 30*HZ, 3, NULL);
	if (result != 0)
	{
		kfree(report_luns);
		return -EBUSY;
	}

	/* get the length from the first four bytes */
	report_len = be32_to_cpu(*(unsigned int*)&report_luns[0]);

	num_luns = (report_len / sizeof(unsigned long long));
	if (num_luns > in_lun_count)
	{
		kfree(report_luns);
		return -EINVAL;
	}

	*lun_count = num_luns;

	DPRINT_DBG(STORVSC_DRV, "report luns on scsi device (%p) found %u luns ", sdev, num_luns);

	/* lun id starts at 1 */
	for (i=1; i< num_luns+1; i++)
	{
		lun = 0;
		data = (unsigned char*)&report_luns[i];
		for (j = 0; j < sizeof(lun); j += 2)
		 {
			 lun = lun | (((data[j] << 8) | data[j + 1]) << (j * 8));
		 }

		luns[i-1] = lun;
	}

	kfree(report_luns);
	return 0;
}

static void storvsc_host_rescan(struct hv_device *device_obj)
{
	struct device_context* device_ctx = to_device_context(device_obj);
	struct Scsi_Host *host = dev_get_drvdata(&device_ctx->device);
	struct host_device_context *host_device_ctx;

	DPRINT_ENTER(STORVSC_DRV);

	host_device_ctx = (struct host_device_context*)host->hostdata;

	DPRINT_INFO(STORVSC_DRV, "initiating rescan on dev obj (%p) target (%u) bus (%u)...", device_obj, host_device_ctx->target, host_device_ctx->path);

	/* We need to queue this since the scanning may block and the caller may be in an intr context */
	/* scsi_queue_work(host, &host_device_ctx->host_rescan_work); */
	schedule_work(&host_device_ctx->host_rescan_work);
	DPRINT_EXIT(STORVSC_DRV);
}

static int storvsc_get_chs(struct scsi_device *sdev, struct block_device * bdev, sector_t capacity, int *info)
{
	sector_t total_sectors = capacity;
	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;

	info[0] = heads;
    info[1] = sectors_per_track;
    info[2] = cylinders;

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

    return 0;
}

MODULE_LICENSE("GPL");

static int __init storvsc_init(void)
{
	int ret;

	DPRINT_ENTER(STORVSC_DRV);

	DPRINT_INFO(STORVSC_DRV, "Storvsc initializing....");

	ret = storvsc_drv_init(StorVscInitialize);

	DPRINT_EXIT(STORVSC_DRV);

	return ret;
}

static void __exit storvsc_exit(void)
{
	DPRINT_ENTER(STORVSC_DRV);

	storvsc_drv_exit();

	DPRINT_ENTER(STORVSC_DRV);
}

module_param(storvsc_ringbuffer_size, int, S_IRUGO);

module_init(storvsc_init);
module_exit(storvsc_exit);

/* eof */