[RFC PATCH 15/28] block: Support counting dma-direct bio segments

Logan Gunthorpe
2019-06-20T16:12:27Z

Change __blk_recalc_rq_segments() to loop through dma_vecs when
appropriate. It calls vec_split_segs() for each dma_vec or bio_vec.

Once this is done the bvec_split_segs() helper is no longer used.

Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
---
block/blk-merge.c | 41 ++++++++++++++++++++++++++++++-----------
1 file changed, 30 insertions(+), 11 deletions(-)

diff --git a/block/blk-merge.c b/block/blk-merge.c
index c4c016f994f6..a7a5453987f9 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -194,13 +194,6 @@ static bool vec_split_segs(struct request_queue *q, unsigned offset,
return !!len;
}

-static bool bvec_split_segs(struct request_queue *q, struct bio_vec *bv,
- unsigned *nsegs, unsigned *sectors, unsigned max_segs)
-{
- return vec_split_segs(q, bv->bv_offset, bv->bv_len, nsegs,
- sectors, max_segs);
-}
-
struct blk_segment_split_ctx {
unsigned nsegs;
unsigned sectors;
@@ -366,12 +359,36 @@ void blk_queue_split(struct request_queue *q, struct bio **bio)
}
EXPORT_SYMBOL(blk_queue_split);

+static unsigned int bio_calc_segs(struct request_queue *q, struct bio *bio)
+{
+ unsigned int nsegs = 0;
+ struct bvec_iter iter;
+ struct bio_vec bv;
+
+ bio_for_each_bvec(bv, bio, iter)
+ vec_split_segs(q, bv.bv_offset, bv.bv_len, &nsegs,
+ NULL, UINT_MAX);
+
+ return nsegs;
+}
+
+static unsigned int bio_dma_calc_segs(struct request_queue *q, struct bio *bio)
+{
+ unsigned int nsegs = 0;
+ struct bvec_iter iter;
+ struct dma_vec dv;
+
+ bio_for_each_dvec(dv, bio, iter)
+ vec_split_segs(q, dv.dv_addr, dv.dv_len, &nsegs,
+ NULL, UINT_MAX);
+
+ return nsegs;
+}
+
static unsigned int __blk_recalc_rq_segments(struct request_queue *q,
struct bio *bio)
{
unsigned int nr_phys_segs = 0;
- struct bvec_iter iter;
- struct bio_vec bv;

if (!bio)
return 0;
@@ -386,8 +403,10 @@ static unsigned int __blk_recalc_rq_segments(struct request_queue *q,
}

for_each_bio(bio) {
- bio_for_each_bvec(bv, bio, iter)
- bvec_split_segs(q, &bv, &nr_phys_segs, NULL, UINT_MAX);
+ if (bio_is_dma_direct(bio))
+ nr_phys_segs += bio_calc_segs(q, bio);
+ else
+ nr_phys_segs += bio_dma_calc_segs(q, bio);
}

return nr_phys_segs;
--
2.20.1