Staging: hv: add the Hyper-V virtual storage driver
authorHank Janssen <hjanssen@microsoft.com>
Mon, 13 Jul 2009 23:01:31 +0000 (16:01 -0700)
committerGreg Kroah-Hartman <gregkh@suse.de>
Tue, 15 Sep 2009 19:01:43 +0000 (12:01 -0700)
This is the virtual storage driver when running Linux on top of Hyper-V.

Signed-off-by: Hank Janssen <hjanssen@microsoft.com>
Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
drivers/staging/hv/StorVsc.c [new file with mode: 0644]
drivers/staging/hv/storvsc_drv.c [new file with mode: 0644]

diff --git a/drivers/staging/hv/StorVsc.c b/drivers/staging/hv/StorVsc.c
new file mode 100644 (file)
index 0000000..8a1d776
--- /dev/null
@@ -0,0 +1,967 @@
+/*
+ *
+ * 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 "logging.h"
+
+#include "StorVscApi.h"
+#include "VmbusPacketFormat.h"
+#include "vstorage.h"
+
+
+//
+// #defines
+//
+
+//
+// Data types
+//
+
+typedef struct _STORVSC_REQUEST_EXTENSION {
+       //LIST_ENTRY                                            ListEntry;
+
+       STORVSC_REQUEST                                 *Request;
+       DEVICE_OBJECT                                   *Device;
+
+       // Synchronize the request/response if needed
+       HANDLE                                                  WaitEvent;
+
+       VSTOR_PACKET                                    VStorPacket;
+} STORVSC_REQUEST_EXTENSION;
+
+
+// A storvsc device is a device object that contains a vmbus channel
+typedef struct _STORVSC_DEVICE{
+       DEVICE_OBJECT                           *Device;
+
+       int                                                     RefCount; // 0 indicates the device is being destroyed
+
+       int                                                     NumOutstandingRequests;
+
+       //  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
+       ULONG                                           PortNumber;
+    UCHAR                                              PathId;
+    UCHAR                                              TargetId;
+
+       //LIST_ENTRY                                    OutstandingRequestList;
+       //HANDLE                                                OutstandingRequestLock;
+
+       // Used for vsc/vsp channel reset process
+       STORVSC_REQUEST_EXTENSION       InitRequest;
+
+       STORVSC_REQUEST_EXTENSION       ResetRequest;
+
+} STORVSC_DEVICE;
+
+
+//
+// Globals
+//
+static const char* gDriverName="storvsc";
+
+//{ba6163d9-04a1-4d29-b605-72e2ffb1dc7f}
+static const GUID gStorVscDeviceType={
+       .Data = {0xd9, 0x63, 0x61, 0xba, 0xa1, 0x04, 0x29, 0x4d, 0xb6, 0x05, 0x72, 0xe2, 0xff, 0xb1, 0xdc, 0x7f}
+};
+
+//
+// Internal routines
+//
+static int
+StorVscOnDeviceAdd(
+       DEVICE_OBJECT   *Device,
+       void                    *AdditionalInfo
+       );
+
+static int
+StorVscOnDeviceRemove(
+       DEVICE_OBJECT   *Device
+       );
+
+static int
+StorVscOnIORequest(
+       DEVICE_OBJECT   *Device,
+       STORVSC_REQUEST *Request
+       );
+
+static int
+StorVscOnHostReset(
+       DEVICE_OBJECT   *Device
+       );
+
+static void
+StorVscOnCleanup(
+       DRIVER_OBJECT   *Device
+       );
+
+static void
+StorVscOnChannelCallback(
+       PVOID Context
+       );
+
+static void
+StorVscOnIOCompletion(
+       DEVICE_OBJECT   *Device,
+       VSTOR_PACKET    *VStorPacket,
+       STORVSC_REQUEST_EXTENSION *RequestExt
+       );
+
+static void
+StorVscOnReceive(
+       DEVICE_OBJECT   *Device,
+       VSTOR_PACKET    *VStorPacket,
+       STORVSC_REQUEST_EXTENSION *RequestExt
+       );
+
+static int
+StorVscConnectToVsp(
+       DEVICE_OBJECT   *Device
+       );
+
+static inline STORVSC_DEVICE* AllocStorDevice(DEVICE_OBJECT *Device)
+{
+       STORVSC_DEVICE *storDevice;
+
+       storDevice = MemAllocZeroed(sizeof(STORVSC_DEVICE));
+       if (!storDevice)
+               return NULL;
+
+       // Set to 2 to allow both inbound and outbound traffics
+       // (ie GetStorDevice() and MustGetStorDevice()) to proceed.
+       InterlockedCompareExchange(&storDevice->RefCount, 2, 0);
+
+       storDevice->Device = Device;
+       Device->Extension = storDevice;
+
+       return storDevice;
+}
+
+static inline void FreeStorDevice(STORVSC_DEVICE *Device)
+{
+       ASSERT(Device->RefCount == 0);
+       MemFree(Device);
+}
+
+// Get the stordevice object iff exists and its refcount > 1
+static inline STORVSC_DEVICE* GetStorDevice(DEVICE_OBJECT *Device)
+{
+       STORVSC_DEVICE *storDevice;
+
+       storDevice = (STORVSC_DEVICE*)Device->Extension;
+       if (storDevice && storDevice->RefCount > 1)
+       {
+               InterlockedIncrement(&storDevice->RefCount);
+       }
+       else
+       {
+               storDevice = NULL;
+       }
+
+       return storDevice;
+}
+
+// Get the stordevice object iff exists and its refcount > 0
+static inline STORVSC_DEVICE* MustGetStorDevice(DEVICE_OBJECT *Device)
+{
+       STORVSC_DEVICE *storDevice;
+
+       storDevice = (STORVSC_DEVICE*)Device->Extension;
+       if (storDevice && storDevice->RefCount)
+       {
+               InterlockedIncrement(&storDevice->RefCount);
+       }
+       else
+       {
+               storDevice = NULL;
+       }
+
+       return storDevice;
+}
+
+static inline void PutStorDevice(DEVICE_OBJECT *Device)
+{
+       STORVSC_DEVICE *storDevice;
+
+       storDevice = (STORVSC_DEVICE*)Device->Extension;
+       ASSERT(storDevice);
+
+       InterlockedDecrement(&storDevice->RefCount);
+       ASSERT(storDevice->RefCount);
+}
+
+// Drop ref count to 1 to effectively disable GetStorDevice()
+static inline STORVSC_DEVICE* ReleaseStorDevice(DEVICE_OBJECT *Device)
+{
+       STORVSC_DEVICE *storDevice;
+
+       storDevice = (STORVSC_DEVICE*)Device->Extension;
+       ASSERT(storDevice);
+
+       // Busy wait until the ref drop to 2, then set it to 1
+       while (InterlockedCompareExchange(&storDevice->RefCount, 1, 2) != 2)
+       {
+               Sleep(100);
+       }
+
+       return storDevice;
+}
+
+// Drop ref count to 0. No one can use StorDevice object.
+static inline STORVSC_DEVICE* FinalReleaseStorDevice(DEVICE_OBJECT *Device)
+{
+       STORVSC_DEVICE *storDevice;
+
+       storDevice = (STORVSC_DEVICE*)Device->Extension;
+       ASSERT(storDevice);
+
+       // Busy wait until the ref drop to 1, then set it to 0
+       while (InterlockedCompareExchange(&storDevice->RefCount, 0, 1) != 1)
+       {
+               Sleep(100);
+       }
+
+       Device->Extension = NULL;
+       return storDevice;
+}
+
+/*++;
+
+
+Name:
+       StorVscInitialize()
+
+Description:
+       Main entry point
+
+--*/
+int
+StorVscInitialize(
+       DRIVER_OBJECT *Driver
+       )
+{
+       STORVSC_DRIVER_OBJECT* storDriver = (STORVSC_DRIVER_OBJECT*)Driver;
+       int ret=0;
+
+       DPRINT_ENTER(STORVSC);
+
+       DPRINT_DBG(STORVSC, "sizeof(STORVSC_REQUEST)=%d sizeof(STORVSC_REQUEST_EXTENSION)=%d sizeof(VSTOR_PACKET)=%d, sizeof(VMSCSI_REQUEST)=%d",
+               sizeof(STORVSC_REQUEST), sizeof(STORVSC_REQUEST_EXTENSION), sizeof(VSTOR_PACKET), sizeof(VMSCSI_REQUEST));
+
+       // Make sure we are at least 2 pages since 1 page is used for control
+       ASSERT(storDriver->RingBufferSize >= (PAGE_SIZE << 1));
+
+       Driver->name = gDriverName;
+       memcpy(&Driver->deviceType, &gStorVscDeviceType, sizeof(GUID));
+
+       storDriver->RequestExtSize                      = sizeof(STORVSC_REQUEST_EXTENSION);
+
+       // 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_MULITPAGE_BUFFER + VSTOR_PACKET + UINT64)
+       storDriver->MaxOutstandingRequestsPerChannel =
+               ((storDriver->RingBufferSize - PAGE_SIZE) / ALIGN_UP(MAX_MULTIPAGE_BUFFER_PACKET + sizeof(VSTOR_PACKET) + sizeof(UINT64),sizeof(UINT64)));
+
+       DPRINT_INFO(STORVSC, "max io %u, currently %u\n", storDriver->MaxOutstandingRequestsPerChannel, STORVSC_MAX_IO_REQUESTS);
+
+       // Setup the dispatch table
+       storDriver->Base.OnDeviceAdd                    = StorVscOnDeviceAdd;
+       storDriver->Base.OnDeviceRemove         = StorVscOnDeviceRemove;
+       storDriver->Base.OnCleanup                      = StorVscOnCleanup;
+
+       storDriver->OnIORequest                         = StorVscOnIORequest;
+       storDriver->OnHostReset                         = StorVscOnHostReset;
+
+       DPRINT_EXIT(STORVSC);
+
+       return ret;
+}
+
+/*++
+
+Name:
+       StorVscOnDeviceAdd()
+
+Description:
+       Callback when the device belonging to this driver is added
+
+--*/
+int
+StorVscOnDeviceAdd(
+       DEVICE_OBJECT   *Device,
+       void                    *AdditionalInfo
+       )
+{
+       int ret=0;
+       STORVSC_DEVICE *storDevice;
+       //VMSTORAGE_CHANNEL_PROPERTIES *props;
+       STORVSC_DEVICE_INFO *deviceInfo = (STORVSC_DEVICE_INFO*)AdditionalInfo;
+
+       DPRINT_ENTER(STORVSC);
+
+       storDevice = AllocStorDevice(Device);
+       if (!storDevice)
+       {
+               ret = -1;
+               goto Cleanup;
+       }
+
+       // Save the channel properties to our storvsc channel
+       //props = (VMSTORAGE_CHANNEL_PROPERTIES*) channel->offerMsg.Offer.u.Standard.UserDefined;
+
+       // FIXME:
+       // If we support more than 1 scsi channel, we need to set the port number here
+       // to the scsi channel but how do we get the scsi channel prior to the bus scan
+       /*storChannel->PortNumber = 0;
+       storChannel->PathId = props->PathId;
+       storChannel->TargetId = props->TargetId;*/
+
+       storDevice->PortNumber = deviceInfo->PortNumber;
+       // Send it back up
+       ret = StorVscConnectToVsp(Device);
+
+       //deviceInfo->PortNumber = storDevice->PortNumber;
+       deviceInfo->PathId = storDevice->PathId;
+       deviceInfo->TargetId = storDevice->TargetId;
+
+       DPRINT_DBG(STORVSC, "assigned port %u, path %u target %u\n", storDevice->PortNumber, storDevice->PathId, storDevice->TargetId);
+
+Cleanup:
+       DPRINT_EXIT(STORVSC);
+
+       return ret;
+}
+
+static int StorVscChannelInit(DEVICE_OBJECT *Device)
+{
+       int ret=0;
+       STORVSC_DEVICE *storDevice;
+       STORVSC_REQUEST_EXTENSION *request;
+       VSTOR_PACKET *vstorPacket;
+
+       storDevice = GetStorDevice(Device);
+       if (!storDevice)
+       {
+               DPRINT_ERR(STORVSC, "unable to get stor device...device being destroyed?");
+               DPRINT_EXIT(STORVSC);
+               return -1;
+       }
+
+       request = &storDevice->InitRequest;
+       vstorPacket = &request->VStorPacket;
+
+       // Now, initiate the vsc/vsp initialization protocol on the open channel
+
+       memset(request, sizeof(STORVSC_REQUEST_EXTENSION), 0);
+       request->WaitEvent = WaitEventCreate();
+
+       vstorPacket->Operation = VStorOperationBeginInitialization;
+       vstorPacket->Flags = REQUEST_COMPLETION_FLAG;
+
+       /*SpinlockAcquire(gDriverExt.packetListLock);
+       INSERT_TAIL_LIST(&gDriverExt.packetList, &packet->listEntry.entry);
+       SpinlockRelease(gDriverExt.packetListLock);*/
+
+       DPRINT_INFO(STORVSC, "BEGIN_INITIALIZATION_OPERATION...");
+
+       ret = Device->Driver->VmbusChannelInterface.SendPacket(Device,
+                                                                                                                       vstorPacket,
+                                                                                                                       sizeof(VSTOR_PACKET),
+                                                                                                                       (ULONG_PTR)request,
+                                                                                                                       VmbusPacketTypeDataInBand,
+                                                                                                                       VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
+       if ( ret != 0)
+       {
+               DPRINT_ERR(STORVSC, "unable to send BEGIN_INITIALIZATION_OPERATION");
+               goto Cleanup;
+       }
+
+       WaitEventWait(request->WaitEvent);
+
+       if (vstorPacket->Operation != VStorOperationCompleteIo || vstorPacket->Status != 0)
+       {
+               DPRINT_ERR(STORVSC, "BEGIN_INITIALIZATION_OPERATION failed (op %d status 0x%x)", vstorPacket->Operation, vstorPacket->Status);
+               goto Cleanup;
+       }
+
+       DPRINT_INFO(STORVSC, "QUERY_PROTOCOL_VERSION_OPERATION...");
+
+       // reuse the packet for version range supported
+       memset(vstorPacket, sizeof(VSTOR_PACKET), 0);
+       vstorPacket->Operation = VStorOperationQueryProtocolVersion;
+       vstorPacket->Flags = REQUEST_COMPLETION_FLAG;
+
+    vstorPacket->Version.MajorMinor = VMSTOR_PROTOCOL_VERSION_CURRENT;
+    FILL_VMSTOR_REVISION(vstorPacket->Version.Revision);
+
+       ret = Device->Driver->VmbusChannelInterface.SendPacket(Device,
+                                                                                                                       vstorPacket,
+                                                                                                                       sizeof(VSTOR_PACKET),
+                                                                                                                       (ULONG_PTR)request,
+                                                                                                                       VmbusPacketTypeDataInBand,
+                                                                                                                       VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
+       if ( ret != 0)
+       {
+               DPRINT_ERR(STORVSC, "unable to send BEGIN_INITIALIZATION_OPERATION");
+               goto Cleanup;
+       }
+
+       WaitEventWait(request->WaitEvent);
+
+       // TODO: Check returned version
+       if (vstorPacket->Operation != VStorOperationCompleteIo || vstorPacket->Status != 0)
+       {
+               DPRINT_ERR(STORVSC, "QUERY_PROTOCOL_VERSION_OPERATION failed (op %d status 0x%x)", vstorPacket->Operation, vstorPacket->Status);
+               goto Cleanup;
+       }
+
+       // Query channel properties
+       DPRINT_INFO(STORVSC, "QUERY_PROPERTIES_OPERATION...");
+
+       memset(vstorPacket, sizeof(VSTOR_PACKET), 0);
+    vstorPacket->Operation = VStorOperationQueryProperties;
+       vstorPacket->Flags = REQUEST_COMPLETION_FLAG;
+    vstorPacket->StorageChannelProperties.PortNumber = storDevice->PortNumber;
+
+       ret = Device->Driver->VmbusChannelInterface.SendPacket(Device,
+                                                                                                                       vstorPacket,
+                                                                                                                       sizeof(VSTOR_PACKET),
+                                                                                                                       (ULONG_PTR)request,
+                                                                                                                       VmbusPacketTypeDataInBand,
+                                                                                                                       VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
+
+       if ( ret != 0)
+       {
+               DPRINT_ERR(STORVSC, "unable to send QUERY_PROPERTIES_OPERATION");
+               goto Cleanup;
+       }
+
+       WaitEventWait(request->WaitEvent);
+
+       // TODO: Check returned version
+       if (vstorPacket->Operation != VStorOperationCompleteIo || vstorPacket->Status != 0)
+       {
+               DPRINT_ERR(STORVSC, "QUERY_PROPERTIES_OPERATION failed (op %d status 0x%x)", vstorPacket->Operation, vstorPacket->Status);
+               goto Cleanup;
+       }
+
+       //storDevice->PortNumber = vstorPacket->StorageChannelProperties.PortNumber;
+       storDevice->PathId = vstorPacket->StorageChannelProperties.PathId;
+       storDevice->TargetId = vstorPacket->StorageChannelProperties.TargetId;
+
+       DPRINT_DBG(STORVSC, "channel flag 0x%x, max xfer len 0x%x", vstorPacket->StorageChannelProperties.Flags, vstorPacket->StorageChannelProperties.MaxTransferBytes);
+
+       DPRINT_INFO(STORVSC, "END_INITIALIZATION_OPERATION...");
+
+       memset(vstorPacket, sizeof(VSTOR_PACKET), 0);
+    vstorPacket->Operation = VStorOperationEndInitialization;
+       vstorPacket->Flags = REQUEST_COMPLETION_FLAG;
+
+       ret = Device->Driver->VmbusChannelInterface.SendPacket(Device,
+                                                                                                                       vstorPacket,
+                                                                                                                       sizeof(VSTOR_PACKET),
+                                                                                                                       (ULONG_PTR)request,
+                                                                                                                       VmbusPacketTypeDataInBand,
+                                                                                                                       VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
+
+       if ( ret != 0)
+       {
+               DPRINT_ERR(STORVSC, "unable to send END_INITIALIZATION_OPERATION");
+               goto Cleanup;
+       }
+
+       WaitEventWait(request->WaitEvent);
+
+       if (vstorPacket->Operation != VStorOperationCompleteIo || vstorPacket->Status != 0)
+       {
+               DPRINT_ERR(STORVSC, "END_INITIALIZATION_OPERATION failed (op %d status 0x%x)", vstorPacket->Operation, vstorPacket->Status);
+               goto Cleanup;
+       }
+
+       DPRINT_INFO(STORVSC, "**** storage channel up and running!! ****");
+
+Cleanup:
+       if (request->WaitEvent)
+       {
+               WaitEventClose(request->WaitEvent);
+               request->WaitEvent = NULL;
+       }
+
+       PutStorDevice(Device);
+
+       DPRINT_EXIT(STORVSC);
+       return ret;
+}
+
+
+int
+StorVscConnectToVsp(
+       DEVICE_OBJECT   *Device
+       )
+{
+       int ret=0;
+    VMSTORAGE_CHANNEL_PROPERTIES props;
+
+       STORVSC_DRIVER_OBJECT *storDriver = (STORVSC_DRIVER_OBJECT*) Device->Driver;;
+
+       memset(&props, sizeof(VMSTORAGE_CHANNEL_PROPERTIES), 0);
+
+       // Open the channel
+       ret = Device->Driver->VmbusChannelInterface.Open(Device,
+               storDriver->RingBufferSize,
+               storDriver->RingBufferSize,
+               (PVOID)&props,
+               sizeof(VMSTORAGE_CHANNEL_PROPERTIES),
+               StorVscOnChannelCallback,
+               Device
+               );
+
+       DPRINT_DBG(STORVSC, "storage props: path id %d, tgt id %d, max xfer %d", props.PathId, props.TargetId, props.MaxTransferBytes);
+
+       if (ret != 0)
+       {
+               DPRINT_ERR(STORVSC, "unable to open channel: %d", ret);
+               return -1;
+       }
+
+       ret = StorVscChannelInit(Device);
+
+       return ret;
+}
+
+
+/*++
+
+Name:
+       StorVscOnDeviceRemove()
+
+Description:
+       Callback when the our device is being removed
+
+--*/
+int
+StorVscOnDeviceRemove(
+       DEVICE_OBJECT *Device
+       )
+{
+       STORVSC_DEVICE *storDevice;
+       int ret=0;
+
+       DPRINT_ENTER(STORVSC);
+
+       DPRINT_INFO(STORVSC, "disabling storage device (%p)...", Device->Extension);
+
+       storDevice = ReleaseStorDevice(Device);
+
+       // At this point, all outbound traffic should be disable. We only allow inbound traffic (responses) to proceed
+       // so that outstanding requests can be completed.
+       while (storDevice->NumOutstandingRequests)
+       {
+               DPRINT_INFO(STORVSC, "waiting for %d requests to complete...", storDevice->NumOutstandingRequests);
+
+               Sleep(100);
+       }
+
+       DPRINT_INFO(STORVSC, "removing storage device (%p)...", Device->Extension);
+
+       storDevice = FinalReleaseStorDevice(Device);
+
+       DPRINT_INFO(STORVSC, "storage device (%p) safe to remove", storDevice);
+
+       // Close the channel
+       Device->Driver->VmbusChannelInterface.Close(Device);
+
+       FreeStorDevice(storDevice);
+
+       DPRINT_EXIT(STORVSC);
+       return ret;
+}
+
+
+//static void
+//StorVscOnTargetRescan(
+//     void *Context
+//     )
+//{
+//     DEVICE_OBJECT *device=(DEVICE_OBJECT*)Context;
+//     STORVSC_DRIVER_OBJECT *storDriver;
+//
+//     DPRINT_ENTER(STORVSC);
+//
+//     storDriver = (STORVSC_DRIVER_OBJECT*) device->Driver;
+//     storDriver->OnHostRescan(device);
+//
+//     DPRINT_EXIT(STORVSC);
+//}
+
+int
+StorVscOnHostReset(
+       DEVICE_OBJECT *Device
+       )
+{
+       int ret=0;
+
+       STORVSC_DEVICE *storDevice;
+       STORVSC_REQUEST_EXTENSION *request;
+       VSTOR_PACKET *vstorPacket;
+
+       DPRINT_ENTER(STORVSC);
+
+       DPRINT_INFO(STORVSC, "resetting host adapter...");
+
+       storDevice = GetStorDevice(Device);
+       if (!storDevice)
+       {
+               DPRINT_ERR(STORVSC, "unable to get stor device...device being destroyed?");
+               DPRINT_EXIT(STORVSC);
+               return -1;
+       }
+
+       request = &storDevice->ResetRequest;
+       vstorPacket = &request->VStorPacket;
+
+       request->WaitEvent = WaitEventCreate();
+
+    vstorPacket->Operation = VStorOperationResetBus;
+    vstorPacket->Flags = REQUEST_COMPLETION_FLAG;
+    vstorPacket->VmSrb.PathId = storDevice->PathId;
+
+       ret = Device->Driver->VmbusChannelInterface.SendPacket(Device,
+                                                                                                                       vstorPacket,
+                                                                                                                       sizeof(VSTOR_PACKET),
+                                                                                                                       (ULONG_PTR)&storDevice->ResetRequest,
+                                                                                                                       VmbusPacketTypeDataInBand,
+                                                                                                                       VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
+       if (ret != 0)
+       {
+               DPRINT_ERR(STORVSC, "Unable to send reset packet %p ret %d", vstorPacket, ret);
+               goto Cleanup;
+       }
+
+       // FIXME: Add a timeout
+       WaitEventWait(request->WaitEvent);
+
+       WaitEventClose(request->WaitEvent);
+       DPRINT_INFO(STORVSC, "host adapter reset completed");
+
+       // At this point, all outstanding requests in the adapter should have been flushed out and return to us
+
+Cleanup:
+       PutStorDevice(Device);
+       DPRINT_EXIT(STORVSC);
+       return ret;
+}
+
+/*++
+
+Name:
+       StorVscOnIORequest()
+
+Description:
+       Callback to initiate an I/O request
+
+--*/
+int
+StorVscOnIORequest(
+       DEVICE_OBJECT   *Device,
+       STORVSC_REQUEST *Request
+       )
+{
+       STORVSC_DEVICE *storDevice;
+       STORVSC_REQUEST_EXTENSION* requestExtension = (STORVSC_REQUEST_EXTENSION*) Request->Extension;
+       VSTOR_PACKET* vstorPacket =&requestExtension->VStorPacket;
+       int ret=0;
+
+       DPRINT_ENTER(STORVSC);
+
+       storDevice = GetStorDevice(Device);
+
+       DPRINT_DBG(STORVSC, "enter - Device %p, DeviceExt %p, Request %p, Extension %p",
+               Device, storDevice, Request, requestExtension);
+
+       DPRINT_DBG(STORVSC, "req %p len %d bus %d, target %d, lun %d cdblen %d",
+               Request, Request->DataBuffer.Length, Request->Bus, Request->TargetId, Request->LunId, Request->CdbLen);
+
+       if (!storDevice)
+       {
+               DPRINT_ERR(STORVSC, "unable to get stor device...device being destroyed?");
+               DPRINT_EXIT(STORVSC);
+               return -2;
+       }
+
+       //PrintBytes(Request->Cdb, Request->CdbLen);
+
+       requestExtension->Request = Request;
+       requestExtension->Device  = Device;
+
+       memset(vstorPacket, 0 , sizeof(VSTOR_PACKET));
+
+       vstorPacket->Flags |= REQUEST_COMPLETION_FLAG;
+
+    vstorPacket->VmSrb.Length = sizeof(VMSCSI_REQUEST);
+
+       vstorPacket->VmSrb.PortNumber = Request->Host;
+    vstorPacket->VmSrb.PathId = Request->Bus;
+    vstorPacket->VmSrb.TargetId = Request->TargetId;
+    vstorPacket->VmSrb.Lun = Request->LunId;
+
+       vstorPacket->VmSrb.SenseInfoLength = SENSE_BUFFER_SIZE;
+
+       // Copy over the scsi command descriptor block
+    vstorPacket->VmSrb.CdbLength = Request->CdbLen;
+       memcpy(&vstorPacket->VmSrb.Cdb, Request->Cdb, Request->CdbLen);
+
+       vstorPacket->VmSrb.DataIn = Request->Type;
+       vstorPacket->VmSrb.DataTransferLength = Request->DataBuffer.Length;
+
+       vstorPacket->Operation = VStorOperationExecuteSRB;
+
+       DPRINT_DBG(STORVSC, "srb - len %d port %d, path %d, target %d, lun %d senselen %d cdblen %d",
+               vstorPacket->VmSrb.Length,
+               vstorPacket->VmSrb.PortNumber,
+               vstorPacket->VmSrb.PathId,
+               vstorPacket->VmSrb.TargetId,
+               vstorPacket->VmSrb.Lun,
+               vstorPacket->VmSrb.SenseInfoLength,
+               vstorPacket->VmSrb.CdbLength);
+
+       if (requestExtension->Request->DataBuffer.Length)
+       {
+               ret = Device->Driver->VmbusChannelInterface.SendPacketMultiPageBuffer(Device,
+                               &requestExtension->Request->DataBuffer,
+                               vstorPacket,
+                               sizeof(VSTOR_PACKET),
+                               (ULONG_PTR)requestExtension);
+       }
+       else
+       {
+               ret = Device->Driver->VmbusChannelInterface.SendPacket(Device,
+                                                                                                                       vstorPacket,
+                                                                                                                       sizeof(VSTOR_PACKET),
+                                                                                                                       (ULONG_PTR)requestExtension,
+                                                                                                                       VmbusPacketTypeDataInBand,
+                                                                                                                       VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
+       }
+
+       if (ret != 0)
+       {
+               DPRINT_DBG(STORVSC, "Unable to send packet %p ret %d", vstorPacket, ret);
+       }
+
+       InterlockedIncrement(&storDevice->NumOutstandingRequests);
+
+       PutStorDevice(Device);
+
+       DPRINT_EXIT(STORVSC);
+       return ret;
+}
+
+/*++
+
+Name:
+       StorVscOnCleanup()
+
+Description:
+       Perform any cleanup when the driver is removed
+
+--*/
+void
+StorVscOnCleanup(
+       DRIVER_OBJECT *Driver
+       )
+{
+       DPRINT_ENTER(STORVSC);
+       DPRINT_EXIT(STORVSC);
+}
+
+
+static void
+StorVscOnIOCompletion(
+       DEVICE_OBJECT   *Device,
+       VSTOR_PACKET    *VStorPacket,
+       STORVSC_REQUEST_EXTENSION *RequestExt
+       )
+{
+       STORVSC_REQUEST *request;
+       STORVSC_DEVICE *storDevice;
+
+       DPRINT_ENTER(STORVSC);
+
+       storDevice = MustGetStorDevice(Device);
+       if (!storDevice)
+       {
+               DPRINT_ERR(STORVSC, "unable to get stor device...device being destroyed?");
+               DPRINT_EXIT(STORVSC);
+               return;
+       }
+
+       DPRINT_DBG(STORVSC, "IO_COMPLETE_OPERATION - request extension %p completed bytes xfer %u",
+               RequestExt, VStorPacket->VmSrb.DataTransferLength);
+
+       ASSERT(RequestExt != NULL);
+       ASSERT(RequestExt->Request != NULL);
+
+       request = RequestExt->Request;
+
+       ASSERT(request->OnIOCompletion != NULL);
+
+       // Copy over the status...etc
+       request->Status = VStorPacket->VmSrb.ScsiStatus;
+
+       if (request->Status != 0 || VStorPacket->VmSrb.SrbStatus != 1)
+       {
+               DPRINT_WARN(STORVSC, "cmd 0x%x scsi status 0x%x srb status 0x%x\n",
+                       request->Cdb[0],
+                       VStorPacket->VmSrb.ScsiStatus,
+                       VStorPacket->VmSrb.SrbStatus);
+       }
+
+       if ((request->Status & 0xFF) == 0x02) // CHECK_CONDITION
+       {
+               if (VStorPacket->VmSrb.SrbStatus & 0x80) // autosense data available
+               {
+                       DPRINT_WARN(STORVSC, "storvsc pkt %p autosense data valid - len %d\n",
+                               RequestExt, VStorPacket->VmSrb.SenseInfoLength);
+
+                       ASSERT(VStorPacket->VmSrb.SenseInfoLength <=  request->SenseBufferSize);
+                       memcpy(request->SenseBuffer,
+                               VStorPacket->VmSrb.SenseData,
+                               VStorPacket->VmSrb.SenseInfoLength);
+
+                       request->SenseBufferSize = VStorPacket->VmSrb.SenseInfoLength;
+               }
+       }
+
+       // TODO:
+       request->BytesXfer = VStorPacket->VmSrb.DataTransferLength;
+
+       request->OnIOCompletion(request);
+
+       InterlockedDecrement(&storDevice->NumOutstandingRequests);
+
+       PutStorDevice(Device);
+
+       DPRINT_EXIT(STORVSC);
+}
+
+
+static void
+StorVscOnReceive(
+       DEVICE_OBJECT   *Device,
+       VSTOR_PACKET    *VStorPacket,
+       STORVSC_REQUEST_EXTENSION *RequestExt
+       )
+{
+       switch(VStorPacket->Operation)
+       {
+               case VStorOperationCompleteIo:
+
+                       DPRINT_DBG(STORVSC, "IO_COMPLETE_OPERATION");
+                       StorVscOnIOCompletion(Device, VStorPacket, RequestExt);
+                       break;
+
+               //case ENUMERATE_DEVICE_OPERATION:
+
+               //      DPRINT_INFO(STORVSC, "ENUMERATE_DEVICE_OPERATION");
+
+               //      StorVscOnTargetRescan(Device);
+               //      break;
+
+        case VStorOperationRemoveDevice:
+
+                       DPRINT_INFO(STORVSC, "REMOVE_DEVICE_OPERATION");
+                       // TODO:
+                       break;
+
+               default:
+                       DPRINT_INFO(STORVSC, "Unknown operation received - %d", VStorPacket->Operation);
+                       break;
+       }
+}
+
+void
+StorVscOnChannelCallback(
+       PVOID Context
+       )
+{
+       int ret=0;
+       DEVICE_OBJECT *device = (DEVICE_OBJECT*)Context;
+       STORVSC_DEVICE *storDevice;
+       UINT32 bytesRecvd;
+       UINT64 requestId;
+       UCHAR packet[ALIGN_UP(sizeof(VSTOR_PACKET),8)];
+       STORVSC_REQUEST_EXTENSION *request;
+
+       DPRINT_ENTER(STORVSC);
+
+       ASSERT(device);
+
+       storDevice = MustGetStorDevice(device);
+       if (!storDevice)
+       {
+               DPRINT_ERR(STORVSC, "unable to get stor device...device being destroyed?");
+               DPRINT_EXIT(STORVSC);
+               return;
+       }
+
+       do
+       {
+               ret = device->Driver->VmbusChannelInterface.RecvPacket(device,
+                                                                                                                               packet,
+                                                                                                                               ALIGN_UP(sizeof(VSTOR_PACKET),8),
+                                                                                                                               &bytesRecvd,
+                                                                                                                               &requestId);
+               if (ret == 0 && bytesRecvd > 0)
+               {
+                       DPRINT_DBG(STORVSC, "receive %d bytes - tid %llx", bytesRecvd, requestId);
+
+                       //ASSERT(bytesRecvd == sizeof(VSTOR_PACKET));
+
+                       request = (STORVSC_REQUEST_EXTENSION*)(ULONG_PTR)requestId;
+                       ASSERT(request);
+
+                       //if (vstorPacket.Flags & SYNTHETIC_FLAG)
+                       if ((request == &storDevice->InitRequest) || (request == &storDevice->ResetRequest))
+                       {
+                               //DPRINT_INFO(STORVSC, "reset completion - operation %u status %u", vstorPacket.Operation, vstorPacket.Status);
+
+                               memcpy(&request->VStorPacket, packet, sizeof(VSTOR_PACKET));
+
+                               WaitEventSet(request->WaitEvent);
+                       }
+                       else
+                       {
+                               StorVscOnReceive(device, (VSTOR_PACKET*)packet, request);
+                       }
+               }
+               else
+               {
+                       //DPRINT_DBG(STORVSC, "nothing else to read...");
+                       break;
+               }
+       } while (1);
+
+       PutStorDevice(device);
+
+       DPRINT_EXIT(STORVSC);
+       return;
+}
diff --git a/drivers/staging/hv/storvsc_drv.c b/drivers/staging/hv/storvsc_drv.c
new file mode 100644 (file)
index 0000000..d5a337b
--- /dev/null
@@ -0,0 +1,1413 @@
+/*
+ *
+ * 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>
+
+#ifdef KERNEL_2_6_5
+#else
+#include <scsi/scsi_dbg.h>
+#endif
+
+#include "logging.h"
+#include "vmbus.h"
+
+#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
+#ifdef KERNEL_2_6_27
+    struct kmem_cache               *request_pool;
+#else
+    kmem_cache_t                       *request_pool;
+#endif
+    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;
+
+       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);
+#ifdef KERNEL_2_6_27
+static void storvsc_host_rescan_callback(struct work_struct *work);
+#else
+static void storvsc_host_rescan_callback(void* context);
+#endif
+static void storvsc_host_rescan(DEVICE_OBJECT* 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.
+
+--*/
+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));
+
+#if defined(KERNEL_2_6_5) || defined(KERNEL_2_6_9)
+       drv_ctx->driver.probe = storvsc_probe;
+       drv_ctx->driver.remove = storvsc_remove;
+#else
+       drv_ctx->probe = storvsc_probe;
+       drv_ctx->remove = storvsc_remove;
+#endif
+
+       // The driver belongs to vmbus
+       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:
+
+--*/
+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;
+
+#if defined(KERNEL_2_6_5) || defined(KERNEL_2_6_9)
+#define driver_for_each_device(drv, start, data, fn) \
+       struct list_head *ptr, *n; \
+       list_for_each_safe(ptr, n, &((drv)->devices)) {\
+               struct device *curr_dev;\
+               curr_dev = list_entry(ptr, struct device, driver_list);\
+               fn(curr_dev, data);\
+       }
+#endif // KERNEL_2_6_9
+
+       DPRINT_ENTER(STORVSC_DRV);
+
+       while (1)
+       {
+               current_dev = NULL;
+
+               // Get the device
+               driver_for_each_device(&drv_ctx->driver, NULL, (void*)&current_dev, storvsc_drv_exit_cb);
+
+               if (current_dev == NULL)
+                       break;
+
+               // Initiate removal from the top-down
+               device_unregister(current_dev);
+       }
+
+       if (storvsc_drv_obj->Base.OnCleanup)
+               storvsc_drv_obj->Base.OnCleanup(&storvsc_drv_obj->Base);
+
+       vmbus_child_driver_unregister(drv_ctx);
+
+       DPRINT_EXIT(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);
+       DEVICE_OBJECT* 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;
+       }
+
+       device->driver_data = 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;
+
+#if defined(KERNEL_2_6_5) || defined(KERNEL_2_6_9)
+#elif defined(KERNEL_2_6_27)
+       INIT_WORK(&host_device_ctx->host_rescan_work, storvsc_host_rescan_callback);
+#else
+       INIT_WORK(&host_device_ctx->host_rescan_work, storvsc_host_rescan_callback, device_obj);
+#endif
+
+#if defined(KERNEL_2_6_27)
+       host_device_ctx->request_pool =
+           kmem_cache_create
+           (device_ctx->device.bus_id,
+            sizeof(struct storvsc_cmd_request) + storvsc_drv_obj->RequestExtSize,
+            0,
+            SLAB_HWCACHE_ALIGN, NULL);
+#else
+       host_device_ctx->request_pool =
+           kmem_cache_create
+           (device_ctx->device.bus_id,
+            sizeof(struct storvsc_cmd_request) + storvsc_drv_obj->RequestExtSize,
+            0,
+            SLAB_HWCACHE_ALIGN, NULL, NULL);
+#endif
+
+       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);
+       DEVICE_OBJECT* device_obj = &device_ctx->device_obj;
+
+       struct Scsi_Host *host = (struct Scsi_Host *)device->driver_data;
+       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(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 *);
+#if defined(KERNEL_2_6_5) || defined(KERNEL_2_6_9)
+#else
+       struct scsi_sense_hdr sense_hdr;
+#endif
+
+       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
+#ifdef KERNEL_2_6_27
+               copy_from_bounce_buffer(scsi_sglist(scmnd), cmd_request->bounce_sgl, scsi_sg_count(scmnd));
+#else
+               copy_from_bounce_buffer(scmnd->request_buffer, cmd_request->bounce_sgl, scmnd->use_sg);
+#endif
+               destroy_bounce_buffer(cmd_request->bounce_sgl, cmd_request->bounce_sgl_count);
+       }
+
+       scmnd->result = request->Status;
+
+       if (scmnd->result)
+       {
+#if defined(KERNEL_2_6_5) || defined(KERNEL_2_6_9)
+               DPRINT_INFO(STORVSC_DRV, "scsi result nonzero - %d", scmnd->result);
+#else
+               if (scsi_normalize_sense(scmnd->sense_buffer, request->SenseBufferSize, &sense_hdr))
+               {
+                       scsi_print_sense_hdr("storvsc", &sense_hdr);
+               }
+#endif
+       }
+
+       ASSERT(request->BytesXfer <= request->DataBuffer.Length);
+#ifdef KERNEL_2_6_27
+       scsi_set_resid(scmnd, request->DataBuffer.Length - request->BytesXfer);
+#else
+       scmnd->resid = request->DataBuffer.Length - request->BytesXfer;
+#endif
+
+       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 = kzalloc(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;
+               }
+#ifdef KERNEL_2_6_27
+               sg_set_page(&bounce_sgl[i], page_buf, 0, 0);
+#else
+               bounce_sgl[i].page = page_buf;
+               bounce_sgl[i].offset = 0;
+               bounce_sgl[i].length = 0;
+#endif
+       }
+
+       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++)
+       {
+#ifdef KERNEL_2_6_27
+               if ((page_buf = sg_page((&sgl[i]))) != NULL)
+#else
+               if ((page_buf = sgl[i].page) != NULL)
+#endif
+
+               {
+                       __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++)
+       {
+#ifdef KERNEL_2_6_27
+               src_addr = (unsigned long)kmap_atomic(sg_page((&orig_sgl[i])), KM_IRQ0) + orig_sgl[i].offset;
+#else
+               src_addr = (unsigned long)kmap_atomic(orig_sgl[i].page, KM_IRQ0) + orig_sgl[i].offset;
+#endif
+               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)
+               {
+#ifdef KERNEL_2_6_27
+                       bounce_addr = (unsigned long)kmap_atomic(sg_page((&bounce_sgl[j])), KM_IRQ0);
+#else
+                       bounce_addr = (unsigned long)kmap_atomic(bounce_sgl[j].page, KM_IRQ0);
+#endif
+               }
+
+               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)
+                               {
+#ifdef KERNEL_2_6_27
+                                       bounce_addr = (unsigned long)kmap_atomic(sg_page((&bounce_sgl[j])), KM_IRQ0);
+#else
+                                       bounce_addr = (unsigned long)kmap_atomic(bounce_sgl[j].page, KM_IRQ0);
+#endif
+                               }
+                       }
+                       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++)
+       {
+#ifdef KERNEL_2_6_27
+               dest_addr = (unsigned long)kmap_atomic(sg_page((&orig_sgl[i])), KM_IRQ0) + orig_sgl[i].offset;
+#else
+               dest_addr = (unsigned long)kmap_atomic(orig_sgl[i].page, KM_IRQ0) + orig_sgl[i].offset;
+#endif
+               dest = dest_addr;
+               destlen = orig_sgl[i].length;
+               ASSERT(orig_sgl[i].offset + orig_sgl[i].length <= PAGE_SIZE);
+
+               if (j == 0)
+               {
+#ifdef KERNEL_2_6_27
+                       bounce_addr = (unsigned long)kmap_atomic(sg_page((&bounce_sgl[j])), KM_IRQ0);
+#else
+                       bounce_addr = (unsigned long)kmap_atomic(bounce_sgl[j].page, KM_IRQ0);
+#endif
+               }
+
+               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)
+                               {
+#ifdef KERNEL_2_6_27
+                                       bounce_addr = (unsigned long)kmap_atomic(sg_page((&bounce_sgl[j])), KM_IRQ0);
+#else
+                                       bounce_addr = (unsigned long)kmap_atomic(bounce_sgl[j].page, KM_IRQ0);
+#endif
+                               }
+                       }
+                       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;
+
+       STORVSC_REQUEST *request;
+       struct storvsc_cmd_request *cmd_request;
+       unsigned int request_size=0;
+       int i;
+       struct scatterlist *sgl;
+
+       DPRINT_ENTER(STORVSC_DRV);
+
+#ifdef KERNEL_2_6_27
+       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);
+#else
+       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,
+               scmnd->use_sg,
+               scmnd->request_buffer,
+               scmnd->request_bufflen,
+               scmnd->device->queue_depth,
+               scmnd->device->tagged_supported);
+#endif
+
+       // 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;
+
+
+#ifdef KERNEL_2_6_27
+       request->DataBuffer.Length = scsi_bufflen(scmnd);
+       if (scsi_sg_count(scmnd))
+#else
+       request->DataBuffer.Length = scmnd->request_bufflen;
+       if (scmnd->use_sg)
+#endif
+       {
+#ifdef KERNEL_2_6_27
+               sgl = (struct scatterlist*)scsi_sglist(scmnd);
+#else
+               sgl = (struct scatterlist*)(scmnd->request_buffer);
+#endif
+
+               // check if we need to bounce the sgl
+#ifdef KERNEL_2_6_27
+               if (do_bounce_buffer(sgl, scsi_sg_count(scmnd)) != -1)
+#else
+               if (do_bounce_buffer(sgl, scmnd->use_sg) != -1)
+#endif
+               {
+                       DPRINT_INFO(STORVSC_DRV, "need to bounce buffer for this scmnd %p", scmnd);
+#ifdef KERNEL_2_6_27
+                       cmd_request->bounce_sgl = create_bounce_buffer(sgl, scsi_sg_count(scmnd), scsi_bufflen(scmnd));
+#else
+                       cmd_request->bounce_sgl = create_bounce_buffer(
+                           sgl,
+                           scmnd->use_sg, scmnd->request_bufflen);
+#endif
+                       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;
+                       }
+
+#ifdef KERNEL_2_6_27
+                       cmd_request->bounce_sgl_count = ALIGN_UP(scsi_bufflen(scmnd), PAGE_SIZE) >> PAGE_SHIFT;
+#else
+                       cmd_request->bounce_sgl_count = ALIGN_UP(scmnd->request_bufflen, PAGE_SIZE) >> PAGE_SHIFT;
+#endif
+
+                       //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
+#ifdef KERNEL_2_6_27
+                       copy_to_bounce_buffer(sgl, cmd_request->bounce_sgl, scsi_sg_count(scmnd));
+#else
+                       copy_to_bounce_buffer(sgl, cmd_request->bounce_sgl, scmnd->use_sg);
+#endif
+
+                       sgl = cmd_request->bounce_sgl;
+               }
+
+               request->DataBuffer.Offset = sgl[0].offset;
+
+#ifdef KERNEL_2_6_27
+               for (i = 0; i < scsi_sg_count(scmnd); i++ )
+#else
+               for (i = 0; i < scmnd->use_sg; i++ )
+#endif
+               {
+                       DPRINT_DBG(STORVSC_DRV, "sgl[%d] len %d offset %d \n", i, sgl[i].length, sgl[i].offset);
+#ifdef KERNEL_2_6_27
+                       request->DataBuffer.PfnArray[i] = page_to_pfn(sg_page((&sgl[i])));
+#else
+                       request->DataBuffer.PfnArray[i] = page_to_pfn(sgl[i].page);
+#endif
+               }
+       }
+
+#ifdef KERNEL_2_6_27
+       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);
+       }
+#else
+       else if (scmnd->request_buffer)
+       {
+               ASSERT(scmnd->request_bufflen <= PAGE_SIZE);
+               request->DataBuffer.Offset = virt_to_phys(scmnd->request_buffer) & (PAGE_SIZE-1);
+               request->DataBuffer.PfnArray[0] = virt_to_phys(scmnd->request_buffer) >> PAGE_SHIFT;
+       }
+       else
+       {
+               ASSERT(scmnd->request_bufflen == 0);
+       }
+#endif
+
+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
+#ifdef KERNEL_2_6_27
+                       copy_from_bounce_buffer(scsi_sglist(scmnd), cmd_request->bounce_sgl, scsi_sg_count(scmnd));
+#else
+                       copy_from_bounce_buffer(
+                           scmnd->request_buffer,
+                           cmd_request->bounce_sgl,
+                           scmnd->use_sg);
+#endif
+                       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;
+}
+
+#ifdef KERNEL_2_6_27
+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.
+}
+#else
+static int storvsc_merge_bvec(struct request_queue *q, struct bio *bio, struct bio_vec *bvec)
+{
+       // Check if we are adding a new bvec
+       if (bio->bi_vcnt > 0)
+       {
+               //printk("storvsc_merge_bvec() - cnt %u offset %u len %u\n", bio->bi_vcnt, bvec->bv_offset, bvec->bv_len);
+
+               struct bio_vec *prev = &bio->bi_io_vec[bio->bi_vcnt - 1];
+               if (bvec == prev)
+                       return bvec->bv_len; // success
+
+               // Adding new bvec. Make sure the prev one is a complete page
+               if (prev->bv_len == PAGE_SIZE && prev->bv_offset == 0)
+               {
+                       return bvec->bv_len; // success
+               }
+               else
+               {
+                       // Dont reject if the new bvec starts off from the prev one since
+                       // they will be merge into 1 bvec or blk_rq_map_sg() will merge them into 1 sg element
+                       if ((bvec->bv_page == prev->bv_page) &&
+                               (bvec->bv_offset == prev->bv_offset + prev->bv_len))
+                       {
+                               return bvec->bv_len; // success
+                       }
+                       else
+                       {
+                               DPRINT_INFO(STORVSC_DRV, "detected holes in bio request (%p) - cnt %u offset %u len %u", bio, bio->bi_vcnt, bvec->bv_offset, bvec->bv_len);
+                               return 0; // dont add the bvec to this bio since we dont allow holes in the middle of a multi-pages bio
+                       }
+               }
+       }
+
+       return bvec->bv_len; // success
+
+}
+
+#endif
+
+/*++
+
+Name:  storvsc_device_configure()
+
+Desc:  Configure the specified scsi device
+
+--*/
+static int storvsc_device_alloc(struct scsi_device *sdevice)
+{
+#ifdef KERNEL_2_6_5
+#else
+       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;
+#endif
+       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 %d", 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
+
+--*/
+#if defined(KERNEL_2_6_5) || defined(KERNEL_2_6_9)
+#else
+
+#ifdef KERNEL_2_6_27
+static void storvsc_host_rescan_callback(struct work_struct *work)
+{
+       DEVICE_OBJECT* device_obj =
+           &((struct host_device_context*)work)->device_ctx->device_obj;
+#else
+static void storvsc_host_rescan_callback(void* context)
+{
+
+       DEVICE_OBJECT* device_obj = (DEVICE_OBJECT*)context;
+#endif
+       struct device_context* device_ctx = to_device_context(device_obj);
+       struct Scsi_Host *host = (struct Scsi_Host *)device_ctx->device.driver_data;
+       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 = kzalloc(sizeof(unsigned int)*STORVSC_MAX_LUNS_PER_TARGET, GFP_ATOMIC);
+       if (!lun_list)
+       {
+               DPRINT_ERR(STORVSC_DRV, "unable to allocate lun list");
+               return;
+       }
+
+       sdevs_remove_list = kzalloc(sizeof(void*)*STORVSC_MAX_LUNS_PER_TARGET, 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...", device_obj, host_device_ctx->target, host_device_ctx->path);
+
+       // 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;
+#if defined(KERNEL_2_6_5) || defined(KERNEL_2_6_9)
+#else
+       struct scsi_sense_hdr sshdr;
+#endif
+       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);
+       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;
+}
+#endif // KERNEL_2_6_9
+
+static void storvsc_host_rescan(DEVICE_OBJECT* device_obj)
+{
+       struct device_context* device_ctx = to_device_context(device_obj);
+       struct Scsi_Host *host = (struct Scsi_Host *)device_ctx->device.driver_data;
+       struct host_device_context *host_device_ctx;
+
+       DPRINT_ENTER(STORVSC_DRV);
+#if defined(KERNEL_2_6_5) || defined(KERNEL_2_6_9)
+       DPRINT_ERR(STORVSC_DRV, "rescan not supported on 2.6.9 kernels!! You will need to reboot if you have added or removed the scsi lun device");
+#else
+
+       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);
+#endif // KERNEL_2_6_9
+       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