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 @@
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,
