Staging: hv: storvsc: Move the storage driver out of the staging area

The storage driver (storvsc_drv.c) handles all block storage devices
assigned to Linux guests hosted on Hyper-V. This driver has been in the
staging tree for a while and this patch moves it out of the staging area.

James was willing to apply this patch during the 3.3-rc phase and a decision
was taken to defer this to 3.4 since Greg had queued up a bunch of storvsc
patches for 3.4. Now that Greg has applied all of the pending storvsc patches,
I am sending this patch to move this driver out of staging. Based on James'
recommendation, this patch gets rid of the unneeded files in the staging/hv
directory.

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Acked-by: James Bottomley <JBottomley@Parallels.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

3 files changed, 1558 insertions, 0 deletions

diff --git a/drivers/scsi/Kconfig b/drivers/scsi/Kconfig
index 16570aa84aac..d3d18e89cb57 100644
--- a/drivers/scsi/Kconfig
+++ b/drivers/scsi/Kconfig
@@ -662,6 +662,13 @@ config VMWARE_PVSCSI
 	  To compile this driver as a module, choose M here: the
 	  module will be called vmw_pvscsi.
 
+config HYPERV_STORAGE
+	tristate "Microsoft Hyper-V virtual storage driver"
+	depends on SCSI && HYPERV
+	default HYPERV
+	help
+	  Select this option to enable the Hyper-V virtual storage driver.
+
 config LIBFC
 	tristate "LibFC module"
 	select SCSI_FC_ATTRS
diff --git a/drivers/scsi/Makefile b/drivers/scsi/Makefile
index 2b887498be50..e4c1a69f8fab 100644
--- a/drivers/scsi/Makefile
+++ b/drivers/scsi/Makefile
@@ -142,6 +142,7 @@ obj-$(CONFIG_SCSI_BNX2_ISCSI)	+= libiscsi.o bnx2i/
 obj-$(CONFIG_BE2ISCSI)		+= libiscsi.o be2iscsi/
 obj-$(CONFIG_SCSI_PMCRAID)	+= pmcraid.o
 obj-$(CONFIG_VMWARE_PVSCSI)	+= vmw_pvscsi.o
+obj-$(CONFIG_HYPERV_STORAGE)	+= hv_storvsc.o
 
 obj-$(CONFIG_ARM)		+= arm/
 
@@ -170,6 +171,8 @@ scsi_mod-$(CONFIG_SCSI_PROC_FS)	+= scsi_proc.o
 scsi_mod-y			+= scsi_trace.o
 scsi_mod-$(CONFIG_PM)		+= scsi_pm.o
 
+hv_storvsc-y			:= storvsc_drv.o
+
 scsi_tgt-y			+= scsi_tgt_lib.o scsi_tgt_if.o
 
 sd_mod-objs	:= sd.o
diff --git a/drivers/scsi/storvsc_drv.c b/drivers/scsi/storvsc_drv.c
new file mode 100644
index 000000000000..695ffc36e02d
--- /dev/null
+++ b/drivers/scsi/storvsc_drv.c
@@ -0,0 +1,1548 @@
+/*
+ * 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>
+ *   K. Y. Srinivasan <kys@microsoft.com>
+ */
+
+#include <linux/kernel.h>
+#include <linux/wait.h>
+#include <linux/sched.h>
+#include <linux/completion.h>
+#include <linux/string.h>
+#include <linux/mm.h>
+#include <linux/delay.h>
+#include <linux/init.h>
+#include <linux/slab.h>
+#include <linux/module.h>
+#include <linux/device.h>
+#include <linux/hyperv.h>
+#include <linux/mempool.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>
+
+/*
+ * All wire protocol details (storage protocol between the guest and the host)
+ * are consolidated here.
+ *
+ * Begin protocol definitions.
+ */
+
+/*
+ * Version history:
+ * V1 Beta: 0.1
+ * V1 RC < 2008/1/31: 1.0
+ * V1 RC > 2008/1/31:  2.0
+ * Win7: 4.2
+ */
+
+#define VMSTOR_CURRENT_MAJOR  4
+#define VMSTOR_CURRENT_MINOR  2
+
+
+/*  Packet structure describing virtual storage requests. */
+enum vstor_packet_operation {
+	VSTOR_OPERATION_COMPLETE_IO		= 1,
+	VSTOR_OPERATION_REMOVE_DEVICE		= 2,
+	VSTOR_OPERATION_EXECUTE_SRB		= 3,
+	VSTOR_OPERATION_RESET_LUN		= 4,
+	VSTOR_OPERATION_RESET_ADAPTER		= 5,
+	VSTOR_OPERATION_RESET_BUS		= 6,
+	VSTOR_OPERATION_BEGIN_INITIALIZATION	= 7,
+	VSTOR_OPERATION_END_INITIALIZATION	= 8,
+	VSTOR_OPERATION_QUERY_PROTOCOL_VERSION	= 9,
+	VSTOR_OPERATION_QUERY_PROPERTIES	= 10,
+	VSTOR_OPERATION_ENUMERATE_BUS		= 11,
+	VSTOR_OPERATION_MAXIMUM			= 11
+};
+
+/*
+ * Platform neutral description of a scsi request -
+ * this remains the same across the write regardless of 32/64 bit
+ * note: it's patterned off the SCSI_PASS_THROUGH structure
+ */
+#define STORVSC_MAX_CMD_LEN			0x10
+#define STORVSC_SENSE_BUFFER_SIZE		0x12
+#define STORVSC_MAX_BUF_LEN_WITH_PADDING	0x14
+
+struct vmscsi_request {
+	u16 length;
+	u8 srb_status;
+	u8 scsi_status;
+
+	u8  port_number;
+	u8  path_id;
+	u8  target_id;
+	u8  lun;
+
+	u8  cdb_length;
+	u8  sense_info_length;
+	u8  data_in;
+	u8  reserved;
+
+	u32 data_transfer_length;
+
+	union {
+		u8 cdb[STORVSC_MAX_CMD_LEN];
+		u8 sense_data[STORVSC_SENSE_BUFFER_SIZE];
+		u8 reserved_array[STORVSC_MAX_BUF_LEN_WITH_PADDING];
+	};
+} __attribute((packed));
+
+
+/*
+ * This structure is sent during the intialization phase to get the different
+ * properties of the channel.
+ */
+struct vmstorage_channel_properties {
+	u16 protocol_version;
+	u8  path_id;
+	u8 target_id;
+
+	/* Note: port number is only really known on the client side */
+	u32  port_number;
+	u32  flags;
+	u32   max_transfer_bytes;
+
+	/*
+	 * This id is unique for each channel and will correspond with
+	 * vendor specific data in the inquiry data.
+	 */
+
+	u64  unique_id;
+} __packed;
+
+/*  This structure is sent during the storage protocol negotiations. */
+struct vmstorage_protocol_version {
+	/* Major (MSW) and minor (LSW) version numbers. */
+	u16 major_minor;
+
+	/*
+	 * Revision number is auto-incremented whenever this file is changed
+	 * (See FILL_VMSTOR_REVISION macro above).  Mismatch does not
+	 * definitely indicate incompatibility--but it does indicate mismatched
+	 * builds.
+	 * This is only used on the windows side. Just set it to 0.
+	 */
+	u16 revision;
+} __packed;
+
+/* Channel Property Flags */
+#define STORAGE_CHANNEL_REMOVABLE_FLAG		0x1
+#define STORAGE_CHANNEL_EMULATED_IDE_FLAG	0x2
+
+struct vstor_packet {
+	/* Requested operation type */
+	enum vstor_packet_operation operation;
+
+	/*  Flags - see below for values */
+	u32 flags;
+
+	/* Status of the request returned from the server side. */
+	u32 status;
+
+	/* Data payload area */
+	union {
+		/*
+		 * Structure used to forward SCSI commands from the
+		 * client to the server.
+		 */
+		struct vmscsi_request vm_srb;
+
+		/* Structure used to query channel properties. */
+		struct vmstorage_channel_properties storage_channel_properties;
+
+		/* Used during version negotiations. */
+		struct vmstorage_protocol_version version;
+	};
+} __packed;
+
+/*
+ * Packet Flags:
+ *
+ * This flag indicates that the server should send back a completion for this
+ * packet.
+ */
+
+#define REQUEST_COMPLETION_FLAG	0x1
+
+/* Matches Windows-end */
+enum storvsc_request_type {
+	WRITE_TYPE = 0,
+	READ_TYPE,
+	UNKNOWN_TYPE,
+};
+
+/*
+ * SRB status codes and masks; a subset of the codes used here.
+ */
+
+#define SRB_STATUS_AUTOSENSE_VALID	0x80
+#define SRB_STATUS_INVALID_LUN	0x20
+#define SRB_STATUS_SUCCESS	0x01
+#define SRB_STATUS_ERROR	0x04
+
+/*
+ * This is the end of Protocol specific defines.
+ */
+
+
+/*
+ * We setup a mempool to allocate request structures for this driver
+ * on a per-lun basis. The following define specifies the number of
+ * elements in the pool.
+ */
+
+#define STORVSC_MIN_BUF_NR				64
+static int storvsc_ringbuffer_size = (20 * PAGE_SIZE);
+
+module_param(storvsc_ringbuffer_size, int, S_IRUGO);
+MODULE_PARM_DESC(storvsc_ringbuffer_size, "Ring buffer size (bytes)");
+
+#define STORVSC_MAX_IO_REQUESTS				128
+
+/*
+ * In Hyper-V, each port/path/target maps to 1 scsi host adapter.  In
+ * reality, the path/target is not used (ie always set to 0) so our
+ * scsi host adapter essentially has 1 bus with 1 target that contains
+ * up to 256 luns.
+ */
+#define STORVSC_MAX_LUNS_PER_TARGET			64
+#define STORVSC_MAX_TARGETS				1
+#define STORVSC_MAX_CHANNELS				1
+
+
+
+struct storvsc_cmd_request {
+	struct list_head entry;
+	struct scsi_cmnd *cmd;
+
+	unsigned int bounce_sgl_count;
+	struct scatterlist *bounce_sgl;
+
+	struct hv_device *device;
+
+	/* Synchronize the request/response if needed */
+	struct completion wait_event;
+
+	unsigned char *sense_buffer;
+	struct hv_multipage_buffer data_buffer;
+	struct vstor_packet vstor_packet;
+};
+
+
+/* A storvsc device is a device object that contains a vmbus channel */
+struct storvsc_device {
+	struct hv_device *device;
+
+	bool	 destroy;
+	bool	 drain_notify;
+	atomic_t num_outstanding_req;
+	struct Scsi_Host *host;
+
+	wait_queue_head_t waiting_to_drain;
+
+	/*
+	 * Each unique Port/Path/Target represents 1 channel ie scsi
+	 * controller. In reality, the pathid, targetid is always 0
+	 * and the port is set by us
+	 */
+	unsigned int port_number;
+	unsigned char path_id;
+	unsigned char target_id;
+
+	/* Used for vsc/vsp channel reset process */
+	struct storvsc_cmd_request init_request;
+	struct storvsc_cmd_request reset_request;
+};
+
+struct stor_mem_pools {
+	struct kmem_cache *request_pool;
+	mempool_t *request_mempool;
+};
+
+struct hv_host_device {
+	struct hv_device *dev;
+	unsigned int port;
+	unsigned char path;
+	unsigned char target;
+};
+
+struct storvsc_scan_work {
+	struct work_struct work;
+	struct Scsi_Host *host;
+	uint lun;
+};
+
+static void storvsc_bus_scan(struct work_struct *work)
+{
+	struct storvsc_scan_work *wrk;
+	int id, order_id;
+
+	wrk = container_of(work, struct storvsc_scan_work, work);
+	for (id = 0; id < wrk->host->max_id; ++id) {
+		if (wrk->host->reverse_ordering)
+			order_id = wrk->host->max_id - id - 1;
+		else
+			order_id = id;
+
+		scsi_scan_target(&wrk->host->shost_gendev, 0,
+				order_id, SCAN_WILD_CARD, 1);
+	}
+	kfree(wrk);
+}
+
+static void storvsc_remove_lun(struct work_struct *work)
+{
+	struct storvsc_scan_work *wrk;
+	struct scsi_device *sdev;
+
+	wrk = container_of(work, struct storvsc_scan_work, work);
+	if (!scsi_host_get(wrk->host))
+		goto done;
+
+	sdev = scsi_device_lookup(wrk->host, 0, 0, wrk->lun);
+
+	if (sdev) {
+		scsi_remove_device(sdev);
+		scsi_device_put(sdev);
+	}
+	scsi_host_put(wrk->host);
+
+done:
+	kfree(wrk);
+}
+
+/*
+ * Major/minor macros.  Minor version is in LSB, meaning that earlier flat
+ * version numbers will be interpreted as "0.x" (i.e., 1 becomes 0.1).
+ */
+
+static inline u16 storvsc_get_version(u8 major, u8 minor)
+{
+	u16 version;
+
+	version = ((major << 8) | minor);
+	return version;
+}
+
+/*
+ * We can get incoming messages from the host that are not in response to
+ * messages that we have sent out. An example of this would be messages
+ * received by the guest to notify dynamic addition/removal of LUNs. To
+ * deal with potential race conditions where the driver may be in the
+ * midst of being unloaded when we might receive an unsolicited message
+ * from the host, we have implemented a mechanism to gurantee sequential
+ * consistency:
+ *
+ * 1) Once the device is marked as being destroyed, we will fail all
+ *    outgoing messages.
+ * 2) We permit incoming messages when the device is being destroyed,
+ *    only to properly account for messages already sent out.
+ */
+
+static inline struct storvsc_device *get_out_stor_device(
+					struct hv_device *device)
+{
+	struct storvsc_device *stor_device;
+
+	stor_device = hv_get_drvdata(device);
+
+	if (stor_device && stor_device->destroy)
+		stor_device = NULL;
+
+	return stor_device;
+}
+
+
+static inline void storvsc_wait_to_drain(struct storvsc_device *dev)
+{
+	dev->drain_notify = true;
+	wait_event(dev->waiting_to_drain,
+		   atomic_read(&dev->num_outstanding_req) == 0);
+	dev->drain_notify = false;
+}
+
+static inline struct storvsc_device *get_in_stor_device(
+					struct hv_device *device)
+{
+	struct storvsc_device *stor_device;
+
+	stor_device = hv_get_drvdata(device);
+
+	if (!stor_device)
+		goto get_in_err;
+
+	/*
+	 * If the device is being destroyed; allow incoming
+	 * traffic only to cleanup outstanding requests.
+	 */
+
+	if (stor_device->destroy  &&
+		(atomic_read(&stor_device->num_outstanding_req) == 0))
+		stor_device = NULL;
+
+get_in_err:
+	return stor_device;
+
+}
+
+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++) {
+		page_buf = sg_page((&sgl[i]));
+		if (page_buf != NULL)
+			__free_page(page_buf);
+	}
+
+	kfree(sgl);
+}
+
+static int do_bounce_buffer(struct scatterlist *sgl, unsigned int sg_count)
+{
+	int i;
+
+	/* 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 write)
+{
+	int i;
+	int num_pages;
+	struct scatterlist *bounce_sgl;
+	struct page *page_buf;
+	unsigned int buf_len = ((write == WRITE_TYPE) ? 0 : PAGE_SIZE);
+
+	num_pages = ALIGN(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, buf_len, 0);
+	}
+
+	return bounce_sgl;
+
+cleanup:
+	destroy_bounce_buffer(bounce_sgl, num_pages);
+	return NULL;
+}
+
+/* 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,
+					    unsigned int bounce_sgl_count)
+{
+	int i;
+	int 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;
+
+		if (bounce_addr == 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++;
+
+				/*
+				 * It is possible that the number of elements
+				 * in the bounce buffer may not be equal to
+				 * the number of elements in the original
+				 * scatter list. Handle this correctly.
+				 */
+
+				if (j == bounce_sgl_count) {
+					/*
+					 * We are done; cleanup and return.
+					 */
+					kunmap_atomic((void *)(dest_addr -
+							orig_sgl[i].offset),
+							KM_IRQ0);
+					local_irq_restore(flags);
+					return total_copied;
+				}
+
+				/* 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;
+}
+
+/* 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;
+	int 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 (bounce_addr == 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;
+}
+
+static int storvsc_channel_init(struct hv_device *device)
+{
+	struct storvsc_device *stor_device;
+	struct storvsc_cmd_request *request;
+	struct vstor_packet *vstor_packet;
+	int ret, t;
+
+	stor_device = get_out_stor_device(device);
+	if (!stor_device)
+		return -ENODEV;
+
+	request = &stor_device->init_request;
+	vstor_packet = &request->vstor_packet;
+
+	/*
+	 * Now, initiate the vsc/vsp initialization protocol on the open
+	 * channel
+	 */
+	memset(request, 0, sizeof(struct storvsc_cmd_request));
+	init_completion(&request->wait_event);
+	vstor_packet->operation = VSTOR_OPERATION_BEGIN_INITIALIZATION;
+	vstor_packet->flags = REQUEST_COMPLETION_FLAG;
+
+	ret = vmbus_sendpacket(device->channel, vstor_packet,
+			       sizeof(struct vstor_packet),
+			       (unsigned long)request,
+			       VM_PKT_DATA_INBAND,
+			       VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
+	if (ret != 0)
+		goto cleanup;
+
+	t = wait_for_completion_timeout(&request->wait_event, 5*HZ);
+	if (t == 0) {
+		ret = -ETIMEDOUT;
+		goto cleanup;
+	}
+
+	if (vstor_packet->operation != VSTOR_OPERATION_COMPLETE_IO ||
+	    vstor_packet->status != 0)
+		goto cleanup;
+
+
+	/* reuse the packet for version range supported */
+	memset(vstor_packet, 0, sizeof(struct vstor_packet));
+	vstor_packet->operation = VSTOR_OPERATION_QUERY_PROTOCOL_VERSION;
+	vstor_packet->flags = REQUEST_COMPLETION_FLAG;
+
+	vstor_packet->version.major_minor =
+		storvsc_get_version(VMSTOR_CURRENT_MAJOR, VMSTOR_CURRENT_MINOR);
+
+	/*
+	 * The revision number is only used in Windows; set it to 0.
+	 */
+	vstor_packet->version.revision = 0;
+
+	ret = vmbus_sendpacket(device->channel, vstor_packet,
+			       sizeof(struct vstor_packet),
+			       (unsigned long)request,
+			       VM_PKT_DATA_INBAND,
+			       VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
+	if (ret != 0)
+		goto cleanup;
+
+	t = wait_for_completion_timeout(&request->wait_event, 5*HZ);
+	if (t == 0) {
+		ret = -ETIMEDOUT;
+		goto cleanup;
+	}
+
+	if (vstor_packet->operation != VSTOR_OPERATION_COMPLETE_IO ||
+	    vstor_packet->status != 0)
+		goto cleanup;
+
+
+	memset(vstor_packet, 0, sizeof(struct vstor_packet));
+	vstor_packet->operation = VSTOR_OPERATION_QUERY_PROPERTIES;
+	vstor_packet->flags = REQUEST_COMPLETION_FLAG;
+	vstor_packet->storage_channel_properties.port_number =
+					stor_device->port_number;
+
+	ret = vmbus_sendpacket(device->channel, vstor_packet,
+			       sizeof(struct vstor_packet),
+			       (unsigned long)request,
+			       VM_PKT_DATA_INBAND,
+			       VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
+
+	if (ret != 0)
+		goto cleanup;
+
+	t = wait_for_completion_timeout(&request->wait_event, 5*HZ);
+	if (t == 0) {
+		ret = -ETIMEDOUT;
+		goto cleanup;
+	}
+
+	if (vstor_packet->operation != VSTOR_OPERATION_COMPLETE_IO ||
+	    vstor_packet->status != 0)
+		goto cleanup;
+
+	stor_device->path_id = vstor_packet->storage_channel_properties.path_id;
+	stor_device->target_id
+		= vstor_packet->storage_channel_properties.target_id;
+
+	memset(vstor_packet, 0, sizeof(struct vstor_packet));
+	vstor_packet->operation = VSTOR_OPERATION_END_INITIALIZATION;
+	vstor_packet->flags = REQUEST_COMPLETION_FLAG;
+
+	ret = vmbus_sendpacket(device->channel, vstor_packet,
+			       sizeof(struct vstor_packet),
+			       (unsigned long)request,
+			       VM_PKT_DATA_INBAND,
+			       VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
+
+	if (ret != 0)
+		goto cleanup;
+
+	t = wait_for_completion_timeout(&request->wait_event, 5*HZ);
+	if (t == 0) {
+		ret = -ETIMEDOUT;
+		goto cleanup;
+	}
+
+	if (vstor_packet->operation != VSTOR_OPERATION_COMPLETE_IO ||
+	    vstor_packet->status != 0)
+		goto cleanup;
+
+
+cleanup:
+	return ret;
+}
+
+
+static void storvsc_command_completion(struct storvsc_cmd_request *cmd_request)
+{
+	struct scsi_cmnd *scmnd = cmd_request->cmd;
+	struct hv_host_device *host_dev = shost_priv(scmnd->device->host);
+	void (*scsi_done_fn)(struct scsi_cmnd *);
+	struct scsi_sense_hdr sense_hdr;
+	struct vmscsi_request *vm_srb;
+	struct storvsc_scan_work *wrk;
+	struct stor_mem_pools *memp = scmnd->device->hostdata;
+
+	vm_srb = &cmd_request->vstor_packet.vm_srb;
+	if (cmd_request->bounce_sgl_count) {
+		if (vm_srb->data_in == READ_TYPE)
+			copy_from_bounce_buffer(scsi_sglist(scmnd),
+					cmd_request->bounce_sgl,
+					scsi_sg_count(scmnd),
+					cmd_request->bounce_sgl_count);
+		destroy_bounce_buffer(cmd_request->bounce_sgl,
+					cmd_request->bounce_sgl_count);
+	}
+
+	/*
+	 * If there is an error; offline the device since all
+	 * error recovery strategies would have already been
+	 * deployed on the host side.
+	 */
+	if (vm_srb->srb_status == SRB_STATUS_ERROR)
+		scmnd->result = DID_TARGET_FAILURE << 16;
+	else
+		scmnd->result = vm_srb->scsi_status;
+
+	/*
+	 * If the LUN is invalid; remove the device.
+	 */
+	if (vm_srb->srb_status == SRB_STATUS_INVALID_LUN) {
+		struct storvsc_device *stor_dev;
+		struct hv_device *dev = host_dev->dev;
+		struct Scsi_Host *host;
+
+		stor_dev = get_in_stor_device(dev);
+		host = stor_dev->host;
+
+		wrk = kmalloc(sizeof(struct storvsc_scan_work),
+				GFP_ATOMIC);
+		if (!wrk) {
+			scmnd->result = DID_TARGET_FAILURE << 16;
+		} else {
+			wrk->host = host;
+			wrk->lun = vm_srb->lun;
+			INIT_WORK(&wrk->work, storvsc_remove_lun);
+			schedule_work(&wrk->work);
+		}
+	}
+
+	if (scmnd->result) {
+		if (scsi_normalize_sense(scmnd->sense_buffer,
+				SCSI_SENSE_BUFFERSIZE, &sense_hdr))
+			scsi_print_sense_hdr("storvsc", &sense_hdr);
+	}
+
+	scsi_set_resid(scmnd,
+		cmd_request->data_buffer.len -
+		vm_srb->data_transfer_length);
+
+	scsi_done_fn = scmnd->scsi_done;
+
+	scmnd->host_scribble = NULL;
+	scmnd->scsi_done = NULL;
+
+	scsi_done_fn(scmnd);
+
+	mempool_free(cmd_request, memp->request_mempool);
+}
+
+static void storvsc_on_io_completion(struct hv_device *device,
+				  struct vstor_packet *vstor_packet,
+				  struct storvsc_cmd_request *request)
+{
+	struct storvsc_device *stor_device;
+	struct vstor_packet *stor_pkt;
+
+	stor_device = hv_get_drvdata(device);
+	stor_pkt = &request->vstor_packet;
+
+	/*
+	 * The current SCSI handling on the host side does
+	 * not correctly handle:
+	 * INQUIRY command with page code parameter set to 0x80
+	 * MODE_SENSE command with cmd[2] == 0x1c
+	 *
+	 * Setup srb and scsi status so this won't be fatal.
+	 * We do this so we can distinguish truly fatal failues
+	 * (srb status == 0x4) and off-line the device in that case.
+	 */
+
+	if ((stor_pkt->vm_srb.cdb[0] == INQUIRY) ||
+	   (stor_pkt->vm_srb.cdb[0] == MODE_SENSE)) {
+		vstor_packet->vm_srb.scsi_status = 0;
+		vstor_packet->vm_srb.srb_status = SRB_STATUS_SUCCESS;
+	}
+
+
+	/* Copy over the status...etc */
+	stor_pkt->vm_srb.scsi_status = vstor_packet->vm_srb.scsi_status;
+	stor_pkt->vm_srb.srb_status = vstor_packet->vm_srb.srb_status;
+	stor_pkt->vm_srb.sense_info_length =
+	vstor_packet->vm_srb.sense_info_length;
+
+	if (vstor_packet->vm_srb.scsi_status != 0 ||
+		vstor_packet->vm_srb.srb_status != SRB_STATUS_SUCCESS){
+		dev_warn(&device->device,
+			 "cmd 0x%x scsi status 0x%x srb status 0x%x\n",
+			 stor_pkt->vm_srb.cdb[0],
+			 vstor_packet->vm_srb.scsi_status,
+			 vstor_packet->vm_srb.srb_status);
+	}
+
+	if ((vstor_packet->vm_srb.scsi_status & 0xFF) == 0x02) {
+		/* CHECK_CONDITION */
+		if (vstor_packet->vm_srb.srb_status &
+			SRB_STATUS_AUTOSENSE_VALID) {
+			/* autosense data available */
+			dev_warn(&device->device,
+				 "stor pkt %p autosense data valid - len %d\n",
+				 request,
+				 vstor_packet->vm_srb.sense_info_length);
+
+			memcpy(request->sense_buffer,
+			       vstor_packet->vm_srb.sense_data,
+			       vstor_packet->vm_srb.sense_info_length);
+
+		}
+	}
+
+	stor_pkt->vm_srb.data_transfer_length =
+	vstor_packet->vm_srb.data_transfer_length;
+
+	storvsc_command_completion(request);
+
+	if (atomic_dec_and_test(&stor_device->num_outstanding_req) &&
+		stor_device->drain_notify)
+		wake_up(&stor_device->waiting_to_drain);
+
+
+}
+
+static void storvsc_on_receive(struct hv_device *device,
+			     struct vstor_packet *vstor_packet,
+			     struct storvsc_cmd_request *request)
+{
+	struct storvsc_scan_work *work;
+	struct storvsc_device *stor_device;
+
+	switch (vstor_packet->operation) {
+	case VSTOR_OPERATION_COMPLETE_IO:
+		storvsc_on_io_completion(device, vstor_packet, request);
+		break;
+
+	case VSTOR_OPERATION_REMOVE_DEVICE:
+	case VSTOR_OPERATION_ENUMERATE_BUS:
+		stor_device = get_in_stor_device(device);
+		work = kmalloc(sizeof(struct storvsc_scan_work), GFP_ATOMIC);
+		if (!work)
+			return;
+
+		INIT_WORK(&work->work, storvsc_bus_scan);
+		work->host = stor_device->host;
+		schedule_work(&work->work);
+		break;
+
+	default:
+		break;
+	}
+}
+
+static void storvsc_on_channel_callback(void *context)
+{
+	struct hv_device *device = (struct hv_device *)context;
+	struct storvsc_device *stor_device;
+	u32 bytes_recvd;
+	u64 request_id;
+	unsigned char packet[ALIGN(sizeof(struct vstor_packet), 8)];
+	struct storvsc_cmd_request *request;
+	int ret;
+
+
+	stor_device = get_in_stor_device(device);
+	if (!stor_device)
+		return;
+
+	do {
+		ret = vmbus_recvpacket(device->channel, packet,
+				       ALIGN(sizeof(struct vstor_packet), 8),
+				       &bytes_recvd, &request_id);
+		if (ret == 0 && bytes_recvd > 0) {
+
+			request = (struct storvsc_cmd_request *)
+					(unsigned long)request_id;
+
+			if ((request == &stor_device->init_request) ||
+			    (request == &stor_device->reset_request)) {
+
+				memcpy(&request->vstor_packet, packet,
+				       sizeof(struct vstor_packet));
+				complete(&request->wait_event);
+			} else {
+				storvsc_on_receive(device,
+						(struct vstor_packet *)packet,
+						request);
+			}
+		} else {
+			break;
+		}
+	} while (1);
+
+	return;
+}
+
+static int storvsc_connect_to_vsp(struct hv_device *device, u32 ring_size)
+{
+	struct vmstorage_channel_properties props;
+	int ret;
+
+	memset(&props, 0, sizeof(struct vmstorage_channel_properties));
+
+	ret = vmbus_open(device->channel,
+			 ring_size,
+			 ring_size,
+			 (void *)&props,
+			 sizeof(struct vmstorage_channel_properties),
+			 storvsc_on_channel_callback, device);
+
+	if (ret != 0)
+		return ret;
+
+	ret = storvsc_channel_init(device);
+
+	return ret;
+}
+
+static int storvsc_dev_remove(struct hv_device *device)
+{
+	struct storvsc_device *stor_device;
+	unsigned long flags;
+
+	stor_device = hv_get_drvdata(device);
+
+	spin_lock_irqsave(&device->channel->inbound_lock, flags);
+	stor_device->destroy = true;
+	spin_unlock_irqrestore(&device->channel->inbound_lock, flags);
+
+	/*
+	 * At this point, all outbound traffic should be disable. We
+	 * only allow inbound traffic (responses) to proceed so that
+	 * outstanding requests can be completed.
+	 */
+
+	storvsc_wait_to_drain(stor_device);
+
+	/*
+	 * Since we have already drained, we don't need to busy wait
+	 * as was done in final_release_stor_device()
+	 * Note that we cannot set the ext pointer to NULL until
+	 * we have drained - to drain the outgoing packets, we need to
+	 * allow incoming packets.
+	 */
+	spin_lock_irqsave(&device->channel->inbound_lock, flags);
+	hv_set_drvdata(device, NULL);
+	spin_unlock_irqrestore(&device->channel->inbound_lock, flags);
+
+	/* Close the channel */
+	vmbus_close(device->channel);
+
+	kfree(stor_device);
+	return 0;
+}
+
+static int storvsc_do_io(struct hv_device *device,
+			      struct storvsc_cmd_request *request)
+{
+	struct storvsc_device *stor_device;
+	struct vstor_packet *vstor_packet;
+	int ret = 0;
+
+	vstor_packet = &request->vstor_packet;
+	stor_device = get_out_stor_device(device);
+
+	if (!stor_device)
+		return -ENODEV;
+
+
+	request->device  = device;
+
+
+	vstor_packet->flags |= REQUEST_COMPLETION_FLAG;
+
+	vstor_packet->vm_srb.length = sizeof(struct vmscsi_request);
+
+
+	vstor_packet->vm_srb.sense_info_length = STORVSC_SENSE_BUFFER_SIZE;
+
+
+	vstor_packet->vm_srb.data_transfer_length =
+	request->data_buffer.len;
+
+	vstor_packet->operation = VSTOR_OPERATION_EXECUTE_SRB;
+
+	if (request->data_buffer.len) {
+		ret = vmbus_sendpacket_multipagebuffer(device->channel,
+				&request->data_buffer,
+				vstor_packet,
+				sizeof(struct vstor_packet),
+				(unsigned long)request);
+	} else {
+		ret = vmbus_sendpacket(device->channel, vstor_packet,
+			       sizeof(struct vstor_packet),
+			       (unsigned long)request,
+			       VM_PKT_DATA_INBAND,
+			       VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
+	}
+
+	if (ret != 0)
+		return ret;
+
+	atomic_inc(&stor_device->num_outstanding_req);
+
+	return ret;
+}
+
+static int storvsc_device_alloc(struct scsi_device *sdevice)
+{
+	struct stor_mem_pools *memp;
+	int number = STORVSC_MIN_BUF_NR;
+
+	memp = kzalloc(sizeof(struct stor_mem_pools), GFP_KERNEL);
+	if (!memp)
+		return -ENOMEM;
+
+	memp->request_pool =
+		kmem_cache_create(dev_name(&sdevice->sdev_dev),
+				sizeof(struct storvsc_cmd_request), 0,
+				SLAB_HWCACHE_ALIGN, NULL);
+
+	if (!memp->request_pool)
+		goto err0;
+
+	memp->request_mempool = mempool_create(number, mempool_alloc_slab,
+						mempool_free_slab,
+						memp->request_pool);
+
+	if (!memp->request_mempool)
+		goto err1;
+
+	sdevice->hostdata = memp;
+
+	return 0;
+
+err1:
+	kmem_cache_destroy(memp->request_pool);
+
+err0:
+	kfree(memp);
+	return -ENOMEM;
+}
+
+static void storvsc_device_destroy(struct scsi_device *sdevice)
+{
+	struct stor_mem_pools *memp = sdevice->hostdata;
+
+	mempool_destroy(memp->request_mempool);
+	kmem_cache_destroy(memp->request_pool);
+	kfree(memp);
+	sdevice->hostdata = NULL;
+}
+
+static int storvsc_device_configure(struct scsi_device *sdevice)
+{
+	scsi_adjust_queue_depth(sdevice, MSG_SIMPLE_TAG,
+				STORVSC_MAX_IO_REQUESTS);
+
+	blk_queue_max_segment_size(sdevice->request_queue, PAGE_SIZE);
+
+	blk_queue_bounce_limit(sdevice->request_queue, BLK_BOUNCE_ANY);
+
+	return 0;
+}
+
+static int storvsc_get_chs(struct scsi_device *sdev, struct block_device * bdev,
+			   sector_t capacity, int *info)
+{
+	sector_t nsect = capacity;
+	sector_t cylinders = nsect;
+	int heads, sectors_pt;
+
+	/*
+	 * We are making up these values; let us keep it simple.
+	 */
+	heads = 0xff;
+	sectors_pt = 0x3f;      /* Sectors per track */
+	sector_div(cylinders, heads * sectors_pt);
+	if ((sector_t)(cylinders + 1) * heads * sectors_pt < nsect)
+		cylinders = 0xffff;
+
+	info[0] = heads;
+	info[1] = sectors_pt;
+	info[2] = (int)cylinders;
+
+	return 0;
+}
+
+static int storvsc_host_reset_handler(struct scsi_cmnd *scmnd)
+{
+	struct hv_host_device *host_dev = shost_priv(scmnd->device->host);
+	struct hv_device *device = host_dev->dev;
+
+	struct storvsc_device *stor_device;
+	struct storvsc_cmd_request *request;
+	struct vstor_packet *vstor_packet;
+	int ret, t;
+
+
+	stor_device = get_out_stor_device(device);
+	if (!stor_device)
+		return FAILED;
+
+	request = &stor_device->reset_request;
+	vstor_packet = &request->vstor_packet;
+
+	init_completion(&request->wait_event);
+
+	vstor_packet->operation = VSTOR_OPERATION_RESET_BUS;
+	vstor_packet->flags = REQUEST_COMPLETION_FLAG;
+	vstor_packet->vm_srb.path_id = stor_device->path_id;
+
+	ret = vmbus_sendpacket(device->channel, vstor_packet,
+			       sizeof(struct vstor_packet),
+			       (unsigned long)&stor_device->reset_request,
+			       VM_PKT_DATA_INBAND,
+			       VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
+	if (ret != 0)
+		return FAILED;
+
+	t = wait_for_completion_timeout(&request->wait_event, 5*HZ);
+	if (t == 0)
+		return TIMEOUT_ERROR;
+
+
+	/*
+	 * At this point, all outstanding requests in the adapter
+	 * should have been flushed out and return to us
+	 */
+
+	return SUCCESS;
+}
+
+static bool storvsc_scsi_cmd_ok(struct scsi_cmnd *scmnd)
+{
+	bool allowed = true;
+	u8 scsi_op = scmnd->cmnd[0];
+
+	switch (scsi_op) {
+	/*
+	 * smartd sends this command and the host does not handle
+	 * this. So, don't send it.
+	 */
+	case SET_WINDOW:
+		scmnd->result = ILLEGAL_REQUEST << 16;
+		allowed = false;
+		break;
+	default:
+		break;
+	}
+	return allowed;
+}
+
+static int storvsc_queuecommand(struct Scsi_Host *host, struct scsi_cmnd *scmnd)
+{
+	int ret;
+	struct hv_host_device *host_dev = shost_priv(host);
+	struct hv_device *dev = host_dev->dev;
+	struct storvsc_cmd_request *cmd_request;
+	unsigned int request_size = 0;
+	int i;
+	struct scatterlist *sgl;
+	unsigned int sg_count = 0;
+	struct vmscsi_request *vm_srb;
+	struct stor_mem_pools *memp = scmnd->device->hostdata;
+
+	if (!storvsc_scsi_cmd_ok(scmnd)) {
+		scmnd->scsi_done(scmnd);
+		return 0;
+	}
+
+	request_size = sizeof(struct storvsc_cmd_request);
+
+	cmd_request = mempool_alloc(memp->request_mempool,
+				       GFP_ATOMIC);
+
+	/*
+	 * We might be invoked in an interrupt context; hence
+	 * mempool_alloc() can fail.
+	 */
+	if (!cmd_request)
+		return SCSI_MLQUEUE_DEVICE_BUSY;
+
+	memset(cmd_request, 0, sizeof(struct storvsc_cmd_request));
+
+	/* Setup the cmd request */
+	cmd_request->cmd = scmnd;
+
+	scmnd->host_scribble = (unsigned char *)cmd_request;
+
+	vm_srb = &cmd_request->vstor_packet.vm_srb;
+
+
+	/* Build the SRB */
+	switch (scmnd->sc_data_direction) {
+	case DMA_TO_DEVICE:
+		vm_srb->data_in = WRITE_TYPE;
+		break;
+	case DMA_FROM_DEVICE:
+		vm_srb->data_in = READ_TYPE;
+		break;
+	default:
+		vm_srb->data_in = UNKNOWN_TYPE;
+		break;
+	}
+
+
+	vm_srb->port_number = host_dev->port;
+	vm_srb->path_id = scmnd->device->channel;
+	vm_srb->target_id = scmnd->device->id;
+	vm_srb->lun = scmnd->device->lun;
+
+	vm_srb->cdb_length = scmnd->cmd_len;
+
+	memcpy(vm_srb->cdb, scmnd->cmnd, vm_srb->cdb_length);
+
+	cmd_request->sense_buffer = scmnd->sense_buffer;
+
+
+	cmd_request->data_buffer.len = scsi_bufflen(scmnd);
+	if (scsi_sg_count(scmnd)) {
+		sgl = (struct scatterlist *)scsi_sglist(scmnd);
+		sg_count = scsi_sg_count(scmnd);
+
+		/* check if we need to bounce the sgl */
+		if (do_bounce_buffer(sgl, scsi_sg_count(scmnd)) != -1) {
+			cmd_request->bounce_sgl =
+				create_bounce_buffer(sgl, scsi_sg_count(scmnd),
+						     scsi_bufflen(scmnd),
+						     vm_srb->data_in);
+			if (!cmd_request->bounce_sgl) {
+				ret = SCSI_MLQUEUE_HOST_BUSY;
+				goto queue_error;
+			}
+
+			cmd_request->bounce_sgl_count =
+				ALIGN(scsi_bufflen(scmnd), PAGE_SIZE) >>
+					PAGE_SHIFT;
+
+			if (vm_srb->data_in == WRITE_TYPE)
+				copy_to_bounce_buffer(sgl,
+					cmd_request->bounce_sgl,
+					scsi_sg_count(scmnd));
+
+			sgl = cmd_request->bounce_sgl;
+			sg_count = cmd_request->bounce_sgl_count;
+		}
+
+		cmd_request->data_buffer.offset = sgl[0].offset;
+
+		for (i = 0; i < sg_count; i++)
+			cmd_request->data_buffer.pfn_array[i] =
+				page_to_pfn(sg_page((&sgl[i])));
+
+	} else if (scsi_sglist(scmnd)) {
+		cmd_request->data_buffer.offset =
+			virt_to_phys(scsi_sglist(scmnd)) & (PAGE_SIZE-1);
+		cmd_request->data_buffer.pfn_array[0] =
+			virt_to_phys(scsi_sglist(scmnd)) >> PAGE_SHIFT;
+	}
+
+	/* Invokes the vsc to start an IO */
+	ret = storvsc_do_io(dev, cmd_request);
+
+	if (ret == -EAGAIN) {
+		/* no more space */
+
+		if (cmd_request->bounce_sgl_count) {
+			destroy_bounce_buffer(cmd_request->bounce_sgl,
+					cmd_request->bounce_sgl_count);
+
+			ret = SCSI_MLQUEUE_DEVICE_BUSY;
+			goto queue_error;
+		}
+	}
+
+	return 0;
+
+queue_error:
+	mempool_free(cmd_request, memp->request_mempool);
+	scmnd->host_scribble = NULL;
+	return ret;
+}
+
+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_destroy =	storvsc_device_destroy,
+	.slave_configure =	storvsc_device_configure,
+	.cmd_per_lun =		1,
+	/* 64 max_queue * 1 target */
+	.can_queue =		STORVSC_MAX_IO_REQUESTS*STORVSC_MAX_TARGETS,
+	.this_id =		-1,
+	/* no use setting to 0 since ll_blk_rw reset it to 1 */
+	/* currently 32 */
+	.sg_tablesize =		MAX_MULTIPAGE_BUFFER_COUNT,
+	.use_clustering =	DISABLE_CLUSTERING,
+	/* Make sure we dont get a sg segment crosses a page boundary */
+	.dma_boundary =		PAGE_SIZE-1,
+};
+
+enum {
+	SCSI_GUID,
+	IDE_GUID,
+};
+
+static const struct hv_vmbus_device_id id_table[] = {
+	/* SCSI guid */
+	{ VMBUS_DEVICE(0xd9, 0x63, 0x61, 0xba, 0xa1, 0x04, 0x29, 0x4d,
+		       0xb6, 0x05, 0x72, 0xe2, 0xff, 0xb1, 0xdc, 0x7f)
+	  .driver_data = SCSI_GUID },
+	/* IDE guid */
+	{ VMBUS_DEVICE(0x32, 0x26, 0x41, 0x32, 0xcb, 0x86, 0xa2, 0x44,
+		       0x9b, 0x5c, 0x50, 0xd1, 0x41, 0x73, 0x54, 0xf5)
+	  .driver_data = IDE_GUID },
+	{ },
+};
+
+MODULE_DEVICE_TABLE(vmbus, id_table);
+
+static int storvsc_probe(struct hv_device *device,
+			const struct hv_vmbus_device_id *dev_id)
+{
+	int ret;
+	struct Scsi_Host *host;
+	struct hv_host_device *host_dev;
+	bool dev_is_ide = ((dev_id->driver_data == IDE_GUID) ? true : false);
+	int target = 0;
+	struct storvsc_device *stor_device;
+
+	host = scsi_host_alloc(&scsi_driver,
+			       sizeof(struct hv_host_device));
+	if (!host)
+		return -ENOMEM;
+
+	host_dev = shost_priv(host);
+	memset(host_dev, 0, sizeof(struct hv_host_device));
+
+	host_dev->port = host->host_no;
+	host_dev->dev = device;
+
+
+	stor_device = kzalloc(sizeof(struct storvsc_device), GFP_KERNEL);
+	if (!stor_device) {
+		ret = -ENOMEM;
+		goto err_out0;
+	}
+
+	stor_device->destroy = false;
+	init_waitqueue_head(&stor_device->waiting_to_drain);
+	stor_device->device = device;
+	stor_device->host = host;
+	hv_set_drvdata(device, stor_device);
+
+	stor_device->port_number = host->host_no;
+	ret = storvsc_connect_to_vsp(device, storvsc_ringbuffer_size);
+	if (ret)
+		goto err_out1;
+
+	host_dev->path = stor_device->path_id;
+	host_dev->target = stor_device->target_id;
+
+	/* max # of devices per target */
+	host->max_lun = STORVSC_MAX_LUNS_PER_TARGET;
+	/* max # of targets per channel */
+	host->max_id = STORVSC_MAX_TARGETS;
+	/* max # of channels */
+	host->max_channel = STORVSC_MAX_CHANNELS - 1;
+	/* max cmd length */
+	host->max_cmd_len = STORVSC_MAX_CMD_LEN;
+
+	/* Register the HBA and start the scsi bus scan */
+	ret = scsi_add_host(host, &device->device);
+	if (ret != 0)
+		goto err_out2;
+
+	if (!dev_is_ide) {
+		scsi_scan_host(host);
+	} else {
+		target = (device->dev_instance.b[5] << 8 |
+			 device->dev_instance.b[4]);
+		ret = scsi_add_device(host, 0, target, 0);
+		if (ret) {
+			scsi_remove_host(host);
+			goto err_out2;
+		}
+	}
+	return 0;
+
+err_out2:
+	/*
+	 * Once we have connected with the host, we would need to
+	 * to invoke storvsc_dev_remove() to rollback this state and
+	 * this call also frees up the stor_device; hence the jump around
+	 * err_out1 label.
+	 */
+	storvsc_dev_remove(device);
+	goto err_out0;
+
+err_out1:
+	kfree(stor_device);
+
+err_out0:
+	scsi_host_put(host);
+	return ret;
+}
+
+static int storvsc_remove(struct hv_device *dev)
+{
+	struct storvsc_device *stor_device = hv_get_drvdata(dev);
+	struct Scsi_Host *host = stor_device->host;
+
+	scsi_remove_host(host);
+	storvsc_dev_remove(dev);
+	scsi_host_put(host);
+
+	return 0;
+}
+
+static struct hv_driver storvsc_drv = {
+	.name = KBUILD_MODNAME,
+	.id_table = id_table,
+	.probe = storvsc_probe,
+	.remove = storvsc_remove,
+};
+
+static int __init storvsc_drv_init(void)
+{
+	u32 max_outstanding_req_per_channel;
+
+	/*
+	 * Divide the ring buffer data size (which is 1 page less
+	 * than the ring buffer size since that page is reserved for
+	 * the ring buffer indices) by the max request size (which is
+	 * vmbus_channel_packet_multipage_buffer + struct vstor_packet + u64)
+	 */
+	max_outstanding_req_per_channel =
+		((storvsc_ringbuffer_size - PAGE_SIZE) /
+		ALIGN(MAX_MULTIPAGE_BUFFER_PACKET +
+		sizeof(struct vstor_packet) + sizeof(u64),
+		sizeof(u64)));
+
+	if (max_outstanding_req_per_channel <
+	    STORVSC_MAX_IO_REQUESTS)
+		return -EINVAL;
+
+	return vmbus_driver_register(&storvsc_drv);
+}
+
+static void __exit storvsc_drv_exit(void)
+{
+	vmbus_driver_unregister(&storvsc_drv);
+}
+
+MODULE_LICENSE("GPL");
+MODULE_VERSION(HV_DRV_VERSION);
+MODULE_DESCRIPTION("Microsoft Hyper-V virtual storage driver");
+module_init(storvsc_drv_init);
+module_exit(storvsc_drv_exit);