[PATCH 34/40] Staging: hv: storvsc: Add the contents of hyperv_storage.h to storvsc_drv.c

["K. Y. Srinivasan" <kys@microsoft.com>]

Add the contents of hyperv_storage.h to storvsc_drv.c and cleanup storvsc_drv.c.n


Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: Abhishek Kane <v-abkane@microsoft.com>
Signed-off-by: Hank Janssen <hjanssen@microsoft.com>
---
 drivers/staging/hv/hyperv_storage.h |  355 -----------------------------------
 drivers/staging/hv/storvsc_drv.c    |  314 ++++++++++++++++++++++++++++++-
 2 files changed, 313 insertions(+), 356 deletions(-)
 delete mode 100644 drivers/staging/hv/hyperv_storage.h

diff --git a/drivers/staging/hv/hyperv_storage.h b/drivers/staging/hv/hyperv_storage.h
deleted file mode 100644
index 865ede1..0000000
--- a/drivers/staging/hv/hyperv_storage.h
+++ /dev/null
@@ -1,355 +0,0 @@
-/*
- *
- * Copyright (c) 2011, 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>
- *
- */
-
-#ifndef _HYPERV_STORAGE_H
-#define _HYPERV_STORAGE_H
-
-/*
- * We want to manage the IDE devices using standard Linux SCSI drivers
- * using the storvsc driver.
- * Define special channels to support this.
- */
-
-#define HV_MAX_IDE_DEVICES	4
-#define HV_IDE_BASE_CHANNEL	10
-#define HV_IDE0_DEV1		HV_IDE_BASE_CHANNEL
-#define HV_IDE0_DEV2		(HV_IDE_BASE_CHANNEL + 1)
-#define HV_IDE1_DEV1		(HV_IDE_BASE_CHANNEL + 2)
-#define HV_IDE1_DEV2		(HV_IDE_BASE_CHANNEL + 3)
-
-
-/* vstorage.w revision number.  This is used in the case of a version match, */
-/* to alert the user that structure sizes may be mismatched even though the */
-/* protocol versions match. */
-
-
-#define REVISION_STRING(REVISION_) #REVISION_
-#define FILL_VMSTOR_REVISION(RESULT_LVALUE_)				\
-	do {								\
-		char *revision_string					\
-			= REVISION_STRING($Rev : 6 $) + 6;		\
-		RESULT_LVALUE_ = 0;					\
-		while (*revision_string >= '0'				\
-			&& *revision_string <= '9') {			\
-			RESULT_LVALUE_ *= 10;				\
-			RESULT_LVALUE_ += *revision_string - '0';	\
-			revision_string++;				\
-		}							\
-	} while (0)
-
-/* 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). */
-#define VMSTOR_PROTOCOL_MAJOR(VERSION_)		(((VERSION_) >> 8) & 0xff)
-#define VMSTOR_PROTOCOL_MINOR(VERSION_)		(((VERSION_))      & 0xff)
-#define VMSTOR_PROTOCOL_VERSION(MAJOR_, MINOR_)	((((MAJOR_) & 0xff) << 8) | \
-						 (((MINOR_) & 0xff)))
-#define VMSTOR_INVALID_PROTOCOL_VERSION		(-1)
-
-/* Version history: */
-/* V1 Beta                    0.1 */
-/* V1 RC < 2008/1/31          1.0 */
-/* V1 RC > 2008/1/31          2.0 */
-#define VMSTOR_PROTOCOL_VERSION_CURRENT VMSTOR_PROTOCOL_VERSION(2, 0)
-
-
-
-
-/*  This will get replaced with the max transfer length that is possible on */
-/*  the host adapter. */
-/*  The max transfer length will be published when we offer a vmbus channel. */
-#define MAX_TRANSFER_LENGTH	0x40000
-#define DEFAULT_PACKET_SIZE (sizeof(struct vmdata_gpa_direct) +	\
-			sizeof(struct vstor_packet) +		\
-			sizesizeof(u64) * (MAX_TRANSFER_LENGTH / PAGE_SIZE)))
-
-
-/*  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_MAXIMUM			= 10
-};
-
-/*
- * 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 CDB16GENERIC_LENGTH			0x10
-
-#ifndef SENSE_BUFFER_SIZE
-#define SENSE_BUFFER_SIZE			0x12
-#endif
-
-#define MAX_DATA_BUF_LEN_WITH_PADDING		0x14
-
-struct vmscsi_request {
-	unsigned short length;
-	unsigned char srb_status;
-	unsigned char scsi_status;
-
-	unsigned char port_number;
-	unsigned char path_id;
-	unsigned char target_id;
-	unsigned char lun;
-
-	unsigned char cdb_length;
-	unsigned char sense_info_length;
-	unsigned char data_in;
-	unsigned char reserved;
-
-	unsigned int data_transfer_length;
-
-	union {
-		unsigned char cdb[CDB16GENERIC_LENGTH];
-		unsigned char sense_data[SENSE_BUFFER_SIZE];
-		unsigned char reserved_array[MAX_DATA_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 {
-	unsigned short protocol_version;
-	unsigned char path_id;
-	unsigned char target_id;
-
-	/* Note: port number is only really known on the client side */
-	unsigned int port_number;
-	unsigned int flags;
-	unsigned int max_transfer_bytes;
-
-	/*  This id is unique for each channel and will correspond with */
-	/*  vendor specific data in the inquirydata */
-	unsigned long long unique_id;
-} __packed;
-
-/*  This structure is sent during the storage protocol negotiations. */
-struct vmstorage_protocol_version {
-	/* Major (MSW) and minor (LSW) version numbers. */
-	unsigned short 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.
-	 */
-	unsigned short 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 */
-	unsigned int flags;
-
-	/* Status of the request returned from the server side. */
-	unsigned int 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
-
-/*  This is the set of flags that the vsc can set in any packets it sends */
-#define VSC_LEGAL_FLAGS		(REQUEST_COMPLETION_FLAG)
-
-
-#include <linux/kernel.h>
-#include <linux/wait.h>
-#include "hyperv_storage.h"
-#include "hyperv.h"
-
-/* Defines */
-#define STORVSC_RING_BUFFER_SIZE			(20*PAGE_SIZE)
-#define BLKVSC_RING_BUFFER_SIZE				(20*PAGE_SIZE)
-
-#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 hv_storvsc_request;
-
-/* Matches Windows-end */
-enum storvsc_request_type {
-	WRITE_TYPE,
-	READ_TYPE,
-	UNKNOWN_TYPE,
-};
-
-
-struct hv_storvsc_request {
-	struct hv_storvsc_request *request;
-	struct hv_device *device;
-
-	/* Synchronize the request/response if needed */
-	struct completion wait_event;
-
-	unsigned char *sense_buffer;
-	void *context;
-	void (*on_io_completion)(struct hv_storvsc_request *request);
-	struct hv_multipage_buffer data_buffer;
-
-	struct vstor_packet vstor_packet;
-};
-
-
-struct storvsc_device_info {
-	u32 ring_buffer_size;
-	unsigned int port_number;
-	unsigned char path_id;
-	unsigned char target_id;
-};
-
-struct storvsc_major_info {
-	int major;
-	int index;
-	bool do_register;
-	char *devname;
-	char *diskname;
-};
-
-/* A storvsc device is a device object that contains a vmbus channel */
-struct storvsc_device {
-	struct hv_device *device;
-
-	/* 0 indicates the device is being destroyed */
-	int	 ref_count;
-	bool	 destroy;
-	bool	 drain_notify;
-	bool	 hba_owner;
-	atomic_t num_outstanding_req;
-
-	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 hv_storvsc_request init_request;
-	struct hv_storvsc_request reset_request;
-};
-
-
-static inline struct storvsc_device *get_out_stor_device(
-					struct hv_device *device)
-{
-	struct storvsc_device *stor_device;
-	unsigned long flags;
-
-	spin_lock_irqsave(&device->ext_lock, flags);
-	stor_device = (struct storvsc_device *)device->ext;
-	if (stor_device && (stor_device->ref_count) &&
-		!stor_device->destroy)
-		stor_device->ref_count++;
-	else
-		stor_device = NULL;
-	spin_unlock_irqrestore(&device->ext_lock, flags);
-
-	return stor_device;
-}
-
-
-static inline void put_stor_device(struct hv_device *device)
-{
-	struct storvsc_device *stor_device;
-	unsigned long flags;
-
-	spin_lock_irqsave(&device->ext_lock, flags);
-	stor_device = (struct storvsc_device *)device->ext;
-
-	stor_device->ref_count--;
-	spin_unlock_irqrestore(&device->ext_lock, flags);
-}
-
-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;
-}
-
-/* Interface */
-
-int storvsc_dev_add(struct hv_device *device,
-				void *additional_info);
-int storvsc_dev_remove(struct hv_device *device);
-
-int storvsc_do_io(struct hv_device *device,
-				struct hv_storvsc_request *request);
-
-int storvsc_get_major_info(struct storvsc_device_info *device_info,
-				struct storvsc_major_info *major_info);
-
-#endif /* _HYPERV_STORAGE_H */
diff --git a/drivers/staging/hv/storvsc_drv.c b/drivers/staging/hv/storvsc_drv.c
index 0702dc0..f54f013 100644
--- a/drivers/staging/hv/storvsc_drv.c
+++ b/drivers/staging/hv/storvsc_drv.c
@@ -21,6 +21,7 @@
  */
 
 #include <linux/kernel.h>
+#include <linux/wait.h>
 #include <linux/sched.h>
 #include <linux/completion.h>
 #include <linux/string.h>
@@ -41,7 +42,318 @@
 #include <scsi/scsi_dbg.h>
 
 #include "hyperv.h"
-#include "hyperv_storage.h"
+
+
+/*
+ * We want to manage the IDE devices using standard Linux SCSI drivers
+ * using the storvsc driver.
+ * Define special channels to support this.
+ */
+
+#define HV_MAX_IDE_DEVICES	4
+#define HV_IDE_BASE_CHANNEL	10
+#define HV_IDE0_DEV1		HV_IDE_BASE_CHANNEL
+#define HV_IDE0_DEV2		(HV_IDE_BASE_CHANNEL + 1)
+#define HV_IDE1_DEV1		(HV_IDE_BASE_CHANNEL + 2)
+#define HV_IDE1_DEV2		(HV_IDE_BASE_CHANNEL + 3)
+
+
+/* vstorage.w revision number.  This is used in the case of a version match, */
+/* to alert the user that structure sizes may be mismatched even though the */
+/* protocol versions match. */
+
+
+#define REVISION_STRING(REVISION_) #REVISION_
+#define FILL_VMSTOR_REVISION(RESULT_LVALUE_)				\
+	do {								\
+		char *revision_string					\
+			= REVISION_STRING($Rev : 6 $) + 6;		\
+		RESULT_LVALUE_ = 0;					\
+		while (*revision_string >= '0'				\
+			&& *revision_string <= '9') {			\
+			RESULT_LVALUE_ *= 10;				\
+			RESULT_LVALUE_ += *revision_string - '0';	\
+			revision_string++;				\
+		}							\
+	} while (0)
+
+/* 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). */
+#define VMSTOR_PROTOCOL_MAJOR(VERSION_)		(((VERSION_) >> 8) & 0xff)
+#define VMSTOR_PROTOCOL_MINOR(VERSION_)		(((VERSION_))      & 0xff)
+#define VMSTOR_PROTOCOL_VERSION(MAJOR_, MINOR_)	((((MAJOR_) & 0xff) << 8) | \
+						 (((MINOR_) & 0xff)))
+#define VMSTOR_INVALID_PROTOCOL_VERSION		(-1)
+
+/* Version history: */
+/* V1 Beta                    0.1 */
+/* V1 RC < 2008/1/31          1.0 */
+/* V1 RC > 2008/1/31          2.0 */
+#define VMSTOR_PROTOCOL_VERSION_CURRENT VMSTOR_PROTOCOL_VERSION(2, 0)
+
+
+
+
+/*  This will get replaced with the max transfer length that is possible on */
+/*  the host adapter. */
+/*  The max transfer length will be published when we offer a vmbus channel. */
+#define MAX_TRANSFER_LENGTH	0x40000
+#define DEFAULT_PACKET_SIZE (sizeof(struct vmdata_gpa_direct) +	\
+			sizeof(struct vstor_packet) +		\
+			sizesizeof(u64) * (MAX_TRANSFER_LENGTH / PAGE_SIZE)))
+
+
+/*  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_MAXIMUM			= 10
+};
+
+/*
+ * 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 CDB16GENERIC_LENGTH			0x10
+
+#ifndef SENSE_BUFFER_SIZE
+#define SENSE_BUFFER_SIZE			0x12
+#endif
+
+#define MAX_DATA_BUF_LEN_WITH_PADDING		0x14
+
+struct vmscsi_request {
+	unsigned short length;
+	unsigned char srb_status;
+	unsigned char scsi_status;
+
+	unsigned char port_number;
+	unsigned char path_id;
+	unsigned char target_id;
+	unsigned char lun;
+
+	unsigned char cdb_length;
+	unsigned char sense_info_length;
+	unsigned char data_in;
+	unsigned char reserved;
+
+	unsigned int data_transfer_length;
+
+	union {
+		unsigned char cdb[CDB16GENERIC_LENGTH];
+		unsigned char sense_data[SENSE_BUFFER_SIZE];
+		unsigned char reserved_array[MAX_DATA_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 {
+	unsigned short protocol_version;
+	unsigned char path_id;
+	unsigned char target_id;
+
+	/* Note: port number is only really known on the client side */
+	unsigned int port_number;
+	unsigned int flags;
+	unsigned int max_transfer_bytes;
+
+	/*  This id is unique for each channel and will correspond with */
+	/*  vendor specific data in the inquirydata */
+	unsigned long long unique_id;
+} __packed;
+
+/*  This structure is sent during the storage protocol negotiations. */
+struct vmstorage_protocol_version {
+	/* Major (MSW) and minor (LSW) version numbers. */
+	unsigned short 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.
+	 */
+	unsigned short 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 */
+	unsigned int flags;
+
+	/* Status of the request returned from the server side. */
+	unsigned int 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
+
+/*  This is the set of flags that the vsc can set in any packets it sends */
+#define VSC_LEGAL_FLAGS		(REQUEST_COMPLETION_FLAG)
+
+
+/* Defines */
+#define STORVSC_RING_BUFFER_SIZE			(20*PAGE_SIZE)
+#define BLKVSC_RING_BUFFER_SIZE				(20*PAGE_SIZE)
+
+#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 hv_storvsc_request;
+
+/* Matches Windows-end */
+enum storvsc_request_type {
+	WRITE_TYPE,
+	READ_TYPE,
+	UNKNOWN_TYPE,
+};
+
+
+struct hv_storvsc_request {
+	struct hv_storvsc_request *request;
+	struct hv_device *device;
+
+	/* Synchronize the request/response if needed */
+	struct completion wait_event;
+
+	unsigned char *sense_buffer;
+	void *context;
+	void (*on_io_completion)(struct hv_storvsc_request *request);
+	struct hv_multipage_buffer data_buffer;
+
+	struct vstor_packet vstor_packet;
+};
+
+
+struct storvsc_device_info {
+	u32 ring_buffer_size;
+	unsigned int port_number;
+	unsigned char path_id;
+	unsigned char target_id;
+};
+
+struct storvsc_major_info {
+	int major;
+	int index;
+	bool do_register;
+	char *devname;
+	char *diskname;
+};
+
+/* A storvsc device is a device object that contains a vmbus channel */
+struct storvsc_device {
+	struct hv_device *device;
+
+	/* 0 indicates the device is being destroyed */
+	int	 ref_count;
+	bool	 destroy;
+	bool	 drain_notify;
+	bool	 hba_owner;
+	atomic_t num_outstanding_req;
+
+	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 hv_storvsc_request init_request;
+	struct hv_storvsc_request reset_request;
+};
+
+
+static inline struct storvsc_device *get_out_stor_device(
+					struct hv_device *device)
+{
+	struct storvsc_device *stor_device;
+	unsigned long flags;
+
+	spin_lock_irqsave(&device->ext_lock, flags);
+	stor_device = (struct storvsc_device *)device->ext;
+	if (stor_device && (stor_device->ref_count) &&
+		!stor_device->destroy)
+		stor_device->ref_count++;
+	else
+		stor_device = NULL;
+	spin_unlock_irqrestore(&device->ext_lock, flags);
+
+	return stor_device;
+}
+
+
+static inline void put_stor_device(struct hv_device *device)
+{
+	struct storvsc_device *stor_device;
+	unsigned long flags;
+
+	spin_lock_irqsave(&device->ext_lock, flags);
+	stor_device = (struct storvsc_device *)device->ext;
+
+	stor_device->ref_count--;
+	spin_unlock_irqrestore(&device->ext_lock, flags);
+}
+
+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 int storvsc_ringbuffer_size = STORVSC_RING_BUFFER_SIZE;
 
-- 
1.7.4.1