block: optionally merge discontiguous discard bios into a single request

[mirror_ubuntu-artful-kernel.git] / block / blk-merge.c

diff --git a/block/blk-merge.c b/block/blk-merge.c
index a373416dbc9a9282cd0a5b7e364bb4e340b79489..2afa262425d102e5c1500912f3b6d77525754566 100644 (file)
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -482,13 +482,6 @@ int blk_rq_map_sg(struct request_queue *q, struct request *rq,
 }
 EXPORT_SYMBOL(blk_rq_map_sg);
 
-static void req_set_nomerge(struct request_queue *q, struct request *req)
-{
-       req->cmd_flags |= REQ_NOMERGE;
-       if (req == q->last_merge)
-               q->last_merge = NULL;
-}
-
 static inline int ll_new_hw_segment(struct request_queue *q,
                                    struct request *req,
                                    struct bio *bio)
@@ -808,9 +801,12 @@ bool blk_rq_merge_ok(struct request *rq, struct bio *bio)
        return true;
 }
 
-int blk_try_merge(struct request *rq, struct bio *bio)
+enum elv_merge blk_try_merge(struct request *rq, struct bio *bio)
 {
-       if (blk_rq_pos(rq) + blk_rq_sectors(rq) == bio->bi_iter.bi_sector)
+       if (req_op(rq) == REQ_OP_DISCARD &&
+           queue_max_discard_segments(rq->q) > 1)
+               return ELEVATOR_DISCARD_MERGE;
+       else if (blk_rq_pos(rq) + blk_rq_sectors(rq) == bio->bi_iter.bi_sector)
                return ELEVATOR_BACK_MERGE;
        else if (blk_rq_pos(rq) - bio_sectors(bio) == bio->bi_iter.bi_sector)
                return ELEVATOR_FRONT_MERGE;