In order to support dma-direct bios, blk_bio_segment_split() will need to operate on both bio_vecs and dma_vecs. In order to do this the code inside bio_for_each_bvec() needs to be moved into a generic helper. Step one to do this is to put some of the variables used inside the loop into a context structure so we don't need to pass a dozen variables to this new function.
Signed-off-by: Logan Gunthorpe <[email protected]> --- block/blk-merge.c | 55 ++++++++++++++++++++++++++++++----------------- 1 file changed, 35 insertions(+), 20 deletions(-) diff --git a/block/blk-merge.c b/block/blk-merge.c index 3581c7ac3c1b..414e61a714bf 100644 --- a/block/blk-merge.c +++ b/block/blk-merge.c @@ -201,63 +201,78 @@ static bool bvec_split_segs(struct request_queue *q, struct bio_vec *bv, sectors, max_segs); } +struct blk_segment_split_ctx { + unsigned nsegs; + unsigned sectors; + + bool prv_valid; + struct bio_vec bvprv; + + const unsigned max_sectors; + const unsigned max_segs; +}; + static struct bio *blk_bio_segment_split(struct request_queue *q, struct bio *bio, struct bio_set *bs, unsigned *segs) { - struct bio_vec bv, bvprv, *bvprvp = NULL; + struct bio_vec bv; struct bvec_iter iter; - unsigned nsegs = 0, sectors = 0; bool do_split = true; struct bio *new = NULL; - const unsigned max_sectors = get_max_io_size(q, bio); - const unsigned max_segs = queue_max_segments(q); + + struct blk_segment_split_ctx ctx = { + .max_sectors = get_max_io_size(q, bio), + .max_segs = queue_max_segments(q), + }; bio_for_each_bvec(bv, bio, iter) { /* * If the queue doesn't support SG gaps and adding this * offset would create a gap, disallow it. */ - if (bvprvp && bvec_gap_to_prev(q, bvprvp, bv.bv_offset)) + if (ctx.prv_valid && bvec_gap_to_prev(q, &ctx.bvprv, + bv.bv_offset)) goto split; - if (sectors + (bv.bv_len >> 9) > max_sectors) { + if (ctx.sectors + (bv.bv_len >> 9) > ctx.max_sectors) { /* * Consider this a new segment if we're splitting in * the middle of this vector. */ - if (nsegs < max_segs && - sectors < max_sectors) { + if (ctx.nsegs < ctx.max_segs && + ctx.sectors < ctx.max_sectors) { /* split in the middle of bvec */ - bv.bv_len = (max_sectors - sectors) << 9; - bvec_split_segs(q, &bv, &nsegs, - §ors, max_segs); + bv.bv_len = + (ctx.max_sectors - ctx.sectors) << 9; + bvec_split_segs(q, &bv, &ctx.nsegs, + &ctx.sectors, ctx.max_segs); } goto split; } - if (nsegs == max_segs) + if (ctx.nsegs == ctx.max_segs) goto split; - bvprv = bv; - bvprvp = &bvprv; + ctx.bvprv = bv; + ctx.prv_valid = true; if (bv.bv_offset + bv.bv_len <= PAGE_SIZE) { - nsegs++; - sectors += bv.bv_len >> 9; - } else if (bvec_split_segs(q, &bv, &nsegs, §ors, - max_segs)) { + ctx.nsegs++; + ctx.sectors += bv.bv_len >> 9; + } else if (bvec_split_segs(q, &bv, &ctx.nsegs, &ctx.sectors, + ctx.max_segs)) { goto split; } } do_split = false; split: - *segs = nsegs; + *segs = ctx.nsegs; if (do_split) { - new = bio_split(bio, sectors, GFP_NOIO, bs); + new = bio_split(bio, ctx.sectors, GFP_NOIO, bs); if (new) bio = new; } -- 2.20.1
