[PATCH] block: support larger block pc requests

This patch modifies blk_rq_map/unmap_user() and the cdrom and scsi_ioctl.c
users so that it supports requests larger than bio by chaining them together.

Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/drivers/cdrom/cdrom.c b/drivers/cdrom/cdrom.c
index 7ea0f48f..2df5cf4 100644
--- a/drivers/cdrom/cdrom.c
+++ b/drivers/cdrom/cdrom.c
@@ -2133,16 +2133,14 @@
 		rq->timeout = 60 * HZ;
 		bio = rq->bio;
 
-		if (rq->bio)
-			blk_queue_bounce(q, &rq->bio);
-
 		if (blk_execute_rq(q, cdi->disk, rq, 0)) {
 			struct request_sense *s = rq->sense;
 			ret = -EIO;
 			cdi->last_sense = s->sense_key;
 		}
 
-		if (blk_rq_unmap_user(bio, len))
+		rq->bio = bio;
+		if (blk_rq_unmap_user(rq))
 			ret = -EFAULT;
 
 		if (ret)