scsi: storvsc: properly set residual data length on errors

commit 40630f46 upstream.

On I/O errors, the Windows driver doesn't set data_transfer_length
on error conditions other than SRB_STATUS_DATA_OVERRUN.
In these cases we need to set data_transfer_length to 0,
indicating there is no data transferred. On SRB_STATUS_DATA_OVERRUN,
data_transfer_length is set by the Windows driver to the actual data transferred.
Reported-by: Shiva Krishna <Shiva.Krishna@nimblestorage.com>
Signed-off-by: Long Li <longli@microsoft.com>
Reviewed-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

drivers/scsi/storvsc_drv.c

@@ -307,6 +307,7 @@ enum storvsc_request_type {
 #define SRB_STATUS_SUCCESS	0x01
 #define SRB_STATUS_ABORTED	0x02
 #define SRB_STATUS_ERROR	0x04
+#define SRB_STATUS_DATA_OVERRUN	0x12
 
 #define SRB_STATUS(status) \
 	(status & ~(SRB_STATUS_AUTOSENSE_VALID | SRB_STATUS_QUEUE_FROZEN))
@@ -1084,6 +1085,7 @@ static void storvsc_command_completion(struct storvsc_cmd_request *cmd_request)
 	void (*scsi_done_fn)(struct scsi_cmnd *);
 	struct scsi_sense_hdr sense_hdr;
 	struct vmscsi_request *vm_srb;
+	u32 data_transfer_length;
 	struct stor_mem_pools *memp = scmnd->device->hostdata;
 	struct Scsi_Host *host;
 	struct storvsc_device *stor_dev;
@@ -1093,6 +1095,7 @@ static void storvsc_command_completion(struct storvsc_cmd_request *cmd_request)
 	host = stor_dev->host;
 
 	vm_srb = &cmd_request->vstor_packet.vm_srb;
+	data_transfer_length = vm_srb->data_transfer_length;
 	if (cmd_request->bounce_sgl_count) {
 		if (vm_srb->data_in == READ_TYPE)
 			copy_from_bounce_buffer(scsi_sglist(scmnd),
@@ -1111,13 +1114,20 @@ static void storvsc_command_completion(struct storvsc_cmd_request *cmd_request)
 			scsi_print_sense_hdr("storvsc", &sense_hdr);
 	}
 
-	if (vm_srb->srb_status != SRB_STATUS_SUCCESS)
+	if (vm_srb->srb_status != SRB_STATUS_SUCCESS) {
 		storvsc_handle_error(vm_srb, scmnd, host, sense_hdr.asc,
 					 sense_hdr.ascq);
+		/*
+		 * The Windows driver set data_transfer_length on
+		 * SRB_STATUS_DATA_OVERRUN. On other errors, this value
+		 * is untouched.  In these cases we set it to 0.
+		 */
+		if (vm_srb->srb_status != SRB_STATUS_DATA_OVERRUN)
+			data_transfer_length = 0;
+	}
 
 	scsi_set_resid(scmnd,
-		cmd_request->data_buffer.len -
-		vm_srb->data_transfer_length);
+		cmd_request->data_buffer.len - data_transfer_length);
 
 	scsi_done_fn = scmnd->scsi_done;