[PATCH] ll_rw_blk: fix missing bounce in blk_rq_map_kern()

I think we might just need the blk_map_kern users now. For the async
execute I added the bounce code already and the block SG_IO has it
atleady. I think the blk_map_kern bounce code got dropped because we
thought the correct gfp_t would be passed in. But I think all we need is
the patch below and all the paths are take care of. The patch is not
tested. Patch was made against scsi-misc.

The last place that is sending non sg commands may just be md/dm-emc.c
but that is is just waiting on alasdair to take some patches that fix
that and a bunch of junk in there including adding bounce support. If
the patch below is ok though and dm-emc finally gets converted then it
will have sg and bonce buffer support.

Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

block/ll_rw_blk.c

@@ -2558,6 +2558,7 @@ int blk_rq_map_kern(request_queue_t *q, struct request *rq, void *kbuf,
 		bio->bi_rw |= (1 << BIO_RW);
 
 	blk_rq_bio_prep(q, rq, bio);
+	blk_queue_bounce(q, &rq->bio);
 	rq->buffer = rq->data = NULL;
 	return 0;
 }