block: optionally merge discontiguous discard bios into a single request

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

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 3d76e860f126688c514da06e8c0dc39c5540d2e4..7412191aee5762d89a0b2dcce10aefbbe89784d5 100644 (file)
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -763,7 +763,7 @@ static bool blk_mq_attempt_merge(struct request_queue *q,
        int checked = 8;
 
        list_for_each_entry_reverse(rq, &ctx->rq_list, queuelist) {
-               int el_ret;
+               bool merged = false;
 
                if (!checked--)
                        break;
@@ -771,26 +771,25 @@ static bool blk_mq_attempt_merge(struct request_queue *q,
                if (!blk_rq_merge_ok(rq, bio))
                        continue;
 
-               el_ret = blk_try_merge(rq, bio);
-               if (el_ret == ELEVATOR_NO_MERGE)
-                       continue;
-
-               if (!blk_mq_sched_allow_merge(q, rq, bio))
+               switch (blk_try_merge(rq, bio)) {
+               case ELEVATOR_BACK_MERGE:
+                       if (blk_mq_sched_allow_merge(q, rq, bio))
+                               merged = bio_attempt_back_merge(q, rq, bio);
                        break;
-
-               if (el_ret == ELEVATOR_BACK_MERGE) {
-                       if (bio_attempt_back_merge(q, rq, bio)) {
-                               ctx->rq_merged++;
-                               return true;
-                       }
+               case ELEVATOR_FRONT_MERGE:
+                       if (blk_mq_sched_allow_merge(q, rq, bio))
+                               merged = bio_attempt_front_merge(q, rq, bio);
                        break;
-               } else if (el_ret == ELEVATOR_FRONT_MERGE) {
-                       if (bio_attempt_front_merge(q, rq, bio)) {
-                               ctx->rq_merged++;
-                               return true;
-                       }
+               case ELEVATOR_DISCARD_MERGE:
+                       merged = bio_attempt_discard_merge(q, rq, bio);
                        break;
+               default:
+                       continue;
                }
+
+               if (merged)
+                       ctx->rq_merged++;
+               return merged;
        }
 
        return false;
@@ -2817,8 +2816,6 @@ void blk_mq_enable_hotplug(void)
 
 static int __init blk_mq_init(void)
 {
-       blk_mq_debugfs_init();
-
        cpuhp_setup_state_multi(CPUHP_BLK_MQ_DEAD, "block/mq:dead", NULL,
                                blk_mq_hctx_notify_dead);