From: Christoph Hellwig <hch@infradead.org>
Date: Fri, 7 Feb 2014 18:22:38 +0000 (-0800)
Subject: blk-mq: handle dma_drain_size
X-Git-Tag: upstream/snapshot3+hdmi~3430^2~18
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=4f7f418c4835d3ce1b66d00502df41f324d13ec0;p=platform%2Fadaptation%2Frenesas_rcar%2Frenesas_kernel.git

blk-mq: handle dma_drain_size

Make blk-mq handle the dma_drain_size field the same way as the old request
path.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
---

diff --git a/block/blk-mq.c b/block/blk-mq.c
index c9306e3..a99bea4 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -582,6 +582,16 @@ static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx)
 		list_del_init(&rq->queuelist);
 		blk_mq_start_request(rq);
 
+		if (q->dma_drain_size && blk_rq_bytes(rq)) {
+			/*
+			 * make sure space for the drain appears we
+			 * know we can do this because max_hw_segments
+			 * has been adjusted to be one fewer than the
+			 * device can handle
+			 */
+			rq->nr_phys_segments++;
+		}
+
 		/*
 		 * Last request in the series. Flag it as such, this
 		 * enables drivers to know when IO should be kicked off,