usb: storage: scsiglue: limit USB3 devices to 2048 sectors

USB3 devices, because they are much newer, have much
less chance of having issues with larger transfers.

We still keep a limit because anything above 2048
sectors really rendered negligible speed
improvements, so we will simply ignore
that. Transferring 1MiB should already give us
pretty good performance.

Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/storage/scsiglue.c

@@ -133,6 +133,11 @@ static int slave_configure(struct scsi_device *sdev)
 		 * let the queue segment size sort out the real limit.
 		 */
 		blk_queue_max_hw_sectors(sdev->request_queue, 0x7FFFFF);
+	} else if (us->pusb_dev->speed >= USB_SPEED_SUPER) {
+		/* USB3 devices will be limited to 2048 sectors. This gives us
+		 * better throughput on most devices.
+		 */
+		blk_queue_max_hw_sectors(sdev->request_queue, 2048);
 	}
 
 	/* Some USB host controllers can't do DMA; they have to use PIO.