scsi: mpt3sas: Remove usage of device_busy counter

Remove usage of device_busy counter from driver. Instead of device_busy
counter now driver uses 'nr_active' counter of request_queue to get the
number of inflight request for a LUN.

Link: https://lore.kernel.org/r/20191226111333.26131-10-sreekanth.reddy@broadcom.com
Signed-off-by: Sreekanth Reddy <sreekanth.reddy@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/mpt3sas/mpt3sas_base.c

@@ -3573,6 +3573,22 @@ _base_get_msix_index(struct MPT3SAS_ADAPTER *ioc,
 	return ioc->cpu_msix_table[raw_smp_processor_id()];
 }
 
+/**
+ * _base_sdev_nr_inflight_request -get number of inflight requests
+ *				   of a request queue.
+ * @q: request_queue object
+ *
+ * returns number of inflight request of a request queue.
+ */
+inline unsigned long
+_base_sdev_nr_inflight_request(struct request_queue *q)
+{
+	struct blk_mq_hw_ctx *hctx = q->queue_hw_ctx[0];
+
+	return atomic_read(&hctx->nr_active);
+}
+
+
 /**
  * _base_get_high_iops_msix_index - get the msix index of
  *				high iops queues
@@ -3592,7 +3608,7 @@ _base_get_high_iops_msix_index(struct MPT3SAS_ADAPTER *ioc,
 	 * reply queues in terms of batch count 16 when outstanding
 	 * IOs on the target device is >=8.
 	 */
-	if (atomic_read(&scmd->device->device_busy) >
+	if (_base_sdev_nr_inflight_request(scmd->device->request_queue) >
 	    MPT3SAS_DEVICE_HIGH_IOPS_DEPTH)
 		return base_mod64((
 		    atomic64_add_return(1, &ioc->high_iops_outstanding) /