blk_rq_map_sg() just needs to move the dma_vec into the dma_address of the sgl. Callers will need to ensure not to call dma_map_sg() for dma-direct requests.
This will likely get less ugly with Christoph's proposed cleanup to the DMA API. It will be much simpler if devices are just calling a dma_map_bio() and don't have to worry about dma-direct requests. Signed-off-by: Logan Gunthorpe <[email protected]> --- block/blk-merge.c | 65 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 65 insertions(+) diff --git a/block/blk-merge.c b/block/blk-merge.c index a7a5453987f9..ccd6c44b9f6e 100644 --- a/block/blk-merge.c +++ b/block/blk-merge.c @@ -545,6 +545,69 @@ static int __blk_bios_map_sg(struct request_queue *q, struct bio *bio, return nsegs; } +static unsigned blk_dvec_map_sg(struct request_queue *q, + struct dma_vec *dvec, struct scatterlist *sglist, + struct scatterlist **sg) +{ + unsigned nbytes = dvec->dv_len; + unsigned nsegs = 0, total = 0; + + while (nbytes > 0) { + unsigned seg_size; + + *sg = blk_next_sg(sg, sglist); + + seg_size = get_max_segment_size(q, total); + seg_size = min(nbytes, seg_size); + + (*sg)->dma_address = dvec->dv_addr + total; + sg_dma_len(*sg) = seg_size; + + total += seg_size; + nbytes -= seg_size; + nsegs++; + } + + return nsegs; +} + +static inline void +__blk_segment_dma_map_sg(struct request_queue *q, struct dma_vec *dvec, + struct scatterlist *sglist, struct dma_vec *dvprv, + struct scatterlist **sg, int *nsegs) +{ + int nbytes = dvec->dv_len; + + if (*sg) { + if ((*sg)->length + nbytes > queue_max_segment_size(q)) + goto new_segment; + if (!dmavec_phys_mergeable(q, dvprv, dvec)) + goto new_segment; + + (*sg)->length += nbytes; + } else { +new_segment: + (*nsegs) += blk_dvec_map_sg(q, dvec, sglist, sg); + } + *dvprv = *dvec; +} + +static int __blk_dma_bios_map_sg(struct request_queue *q, struct bio *bio, + struct scatterlist *sglist, + struct scatterlist **sg) +{ + struct dma_vec dvec, dvprv = {}; + struct bvec_iter iter; + int nsegs = 0; + + for_each_bio(bio) + bio_for_each_dvec(dvec, bio, iter) + __blk_segment_dma_map_sg(q, &dvec, sglist, &dvprv, + sg, &nsegs); + + return nsegs; +} + /* * map a request to scatterlist, return number of sg entries setup. Caller * must make sure sg can hold rq->nr_phys_segments entries @@ -559,6 +622,8 @@ int blk_rq_map_sg(struct request_queue *q, struct request *rq, nsegs = __blk_bvec_map_sg(rq->special_vec, sglist, &sg); else if (rq->bio && bio_op(rq->bio) == REQ_OP_WRITE_SAME) nsegs = __blk_bvec_map_sg(bio_iovec(rq->bio), sglist, &sg); + else if (blk_rq_is_dma_direct(rq)) + nsegs = __blk_dma_bios_map_sg(q, rq->bio, sglist, &sg); else if (rq->bio) nsegs = __blk_bios_map_sg(q, rq->bio, sglist, &sg); -- 2.20.1
