Make blk-mq handle the dma_drain_size field the same way as the old request
path.
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
---
block/blk-mq.c | 10 ++++++++++
1 file changed, 10 insertions(+)
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 6838fe8..0b72927 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -560,6 +560,16 @@ 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,
--
1.7.10.4
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