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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>
This commit is contained in:
Christoph Hellwig 2014-02-07 10:22:38 -08:00 committed by Jens Axboe
parent 6f5ba581c0
commit 4f7f418c48
1 changed files with 10 additions and 0 deletions
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10
block/blk-mq.c
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@ -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,