mpt3sas: Set maximum transfer length per IO to 4MB for VDs

Set maximum transfer length per IO on RAID volumes to 4MB by setting
VD's queue's max_sector to 8192.
Signed-off-by: NChaitra P B <chaitra.basappa@broadcom.com>
Reviewed-by: NTomas Henzl <thenzl@redhat.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/mpt3sas/mpt3sas_base.h

@@ -112,6 +112,8 @@
 #define MPT3SAS_SAS_QUEUE_DEPTH		254
 #define MPT3SAS_RAID_QUEUE_DEPTH	128
 
+#define MPT3SAS_RAID_MAX_SECTORS	8192
+
 #define MPT_NAME_LENGTH			32	/* generic length of strings */
 #define MPT_STRING_LENGTH		64
 

drivers/scsi/mpt3sas/mpt3sas_scsih.c

@@ -1909,6 +1909,14 @@ scsih_slave_configure(struct scsi_device *sdev)
 			    (unsigned long long)raid_device->wwid,
 			    raid_device->num_pds, ds);
 
+		if (shost->max_sectors > MPT3SAS_RAID_MAX_SECTORS) {
+			blk_queue_max_hw_sectors(sdev->request_queue,
+						MPT3SAS_RAID_MAX_SECTORS);
+			sdev_printk(KERN_INFO, sdev,
+					"Set queue's max_sector to: %u\n",
+						MPT3SAS_RAID_MAX_SECTORS);
+		}
+
 		scsih_change_queue_depth(sdev, qdepth);
 
 		/* raid transport support */