block: Use accessor functions for queue limits

Convert all external users of queue limits to using wrapper functions
instead of poking the request queue variables directly.

Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/drivers/cdrom/cdrom.c b/drivers/cdrom/cdrom.c
index cceace6..71d1b9b 100644
--- a/drivers/cdrom/cdrom.c
+++ b/drivers/cdrom/cdrom.c
@@ -2101,8 +2101,8 @@
 		nr = nframes;
 		if (cdi->cdda_method == CDDA_BPC_SINGLE)
 			nr = 1;
-		if (nr * CD_FRAMESIZE_RAW > (q->max_sectors << 9))
-			nr = (q->max_sectors << 9) / CD_FRAMESIZE_RAW;
+		if (nr * CD_FRAMESIZE_RAW > (queue_max_sectors(q) << 9))
+			nr = (queue_max_sectors(q) << 9) / CD_FRAMESIZE_RAW;
 
 		len = nr * CD_FRAMESIZE_RAW;