scsi: storvsc: Add ability to change scsi queue depth

Adding functionality to allow the SCSI queue depth to be changed by
utilizing the "scsi_change_queue_depth" function.

[mkp: checkpatch]
Signed-off-by: Branden Bonaby <brandonbonaby94@gmail.com>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Reviewed-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/storvsc_drv.c

@@ -387,6 +387,7 @@ enum storvsc_request_type {
 
 static int storvsc_ringbuffer_size = (128 * 1024);
 static u32 max_outstanding_req_per_channel;
+static int storvsc_change_queue_depth(struct scsi_device *sdev, int queue_depth);
 
 static int storvsc_vcpus_per_sub_channel = 4;
 
@@ -1711,6 +1712,7 @@ static struct scsi_host_template scsi_driver = {
 	.dma_boundary =		PAGE_SIZE-1,
 	.no_write_same =	1,
 	.track_queue_depth =	1,
+	.change_queue_depth =	storvsc_change_queue_depth,
 };
 
 enum {
@@ -1917,6 +1919,15 @@ static int storvsc_probe(struct hv_device *device,
 	return ret;
 }
 
+/* Change a scsi target's queue depth */
+static int storvsc_change_queue_depth(struct scsi_device *sdev, int queue_depth)
+{
+	if (queue_depth > scsi_driver.can_queue)
+		queue_depth = scsi_driver.can_queue;
+
+	return scsi_change_queue_depth(sdev, queue_depth);
+}
+
 static int storvsc_remove(struct hv_device *dev)
 {
 	struct storvsc_device *stor_device = hv_get_drvdata(dev);