block: simplify blk_recalc_rq_segments

Return the segement and let the callers assign them, which makes the code
a littler more obvious.  Also pass the request instead of q plus bio
chain, allowing for the use of rq_for_each_bvec.

Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/block/blk-merge.c b/block/blk-merge.c
index 72b4fd8..2ea21ff 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -310,17 +310,16 @@
 }
 EXPORT_SYMBOL(blk_queue_split);
 
-static unsigned int __blk_recalc_rq_segments(struct request_queue *q,
-					     struct bio *bio)
+unsigned int blk_recalc_rq_segments(struct request *rq)
 {
 	unsigned int nr_phys_segs = 0;
-	struct bvec_iter iter;
+	struct req_iterator iter;
 	struct bio_vec bv;
 
-	if (!bio)
+	if (!rq->bio)
 		return 0;
 
-	switch (bio_op(bio)) {
+	switch (bio_op(rq->bio)) {
 	case REQ_OP_DISCARD:
 	case REQ_OP_SECURE_ERASE:
 	case REQ_OP_WRITE_ZEROES:
@@ -329,19 +328,11 @@
 		return 1;
 	}
 
-	for_each_bio(bio) {
-		bio_for_each_bvec(bv, bio, iter)
-			bvec_split_segs(q, &bv, &nr_phys_segs, NULL, UINT_MAX);
-	}
-
+	rq_for_each_bvec(bv, rq, iter)
+		bvec_split_segs(rq->q, &bv, &nr_phys_segs, NULL, UINT_MAX);
 	return nr_phys_segs;
 }
 
-void blk_recalc_rq_segments(struct request *rq)
-{
-	rq->nr_phys_segments = __blk_recalc_rq_segments(rq->q, rq->bio);
-}
-
 static inline struct scatterlist *blk_next_sg(struct scatterlist **sg,
 		struct scatterlist *sglist)
 {