blk-mq: fail the request in case issue failure

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

diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c
index c117bd8fd1f6126849472300b3c294e65825a2f7..45d8e861fe55f184929a19ac81a6a70e185163bb 100644 (file)
--- a/block/blk-mq-sched.c
+++ b/block/blk-mq-sched.c
@@ -220,15 +220,8 @@ void blk_mq_sched_dispatch_requests(struct blk_mq_hw_ctx *hctx)
                }
        } else if (has_sched_dispatch) {
                blk_mq_do_dispatch_sched(hctx);
-       } else if (q->mq_ops->get_budget) {
-               /*
-                * If we need to get budget before queuing request, we
-                * dequeue request one by one from sw queue for avoiding
-                * to mess up I/O merge when dispatch runs out of resource.
-                *
-                * TODO: get more budgets, and dequeue more requests in
-                * one time.
-                */
+       } else if (hctx->dispatch_busy) {
+               /* dequeue request one by one from sw queue if queue is busy */
                blk_mq_do_dispatch_ctx(hctx);
        } else {
                blk_mq_flush_busy_ctxs(hctx, &rq_list);
@@ -324,7 +317,8 @@ bool __blk_mq_sched_bio_merge(struct request_queue *q, struct bio *bio)
                return e->type->ops.mq.bio_merge(hctx, bio);
        }
 
-       if (hctx->flags & BLK_MQ_F_SHOULD_MERGE) {
+       if ((hctx->flags & BLK_MQ_F_SHOULD_MERGE) &&
+                       !list_empty_careful(&ctx->rq_list)) {
                /* default per sw-queue merge */
                spin_lock(&ctx->lock);
                ret = blk_mq_attempt_merge(q, ctx, bio);
@@ -428,7 +422,7 @@ done:
 }
 
 void blk_mq_sched_insert_request(struct request *rq, bool at_head,
-                                bool run_queue, bool async, bool can_block)
+                                bool run_queue, bool async)
 {
        struct request_queue *q = rq->q;
        struct elevator_queue *e = q->elevator;
@@ -471,8 +465,19 @@ void blk_mq_sched_insert_requests(struct request_queue *q,
 
        if (e && e->type->ops.mq.insert_requests)
                e->type->ops.mq.insert_requests(hctx, list, false);
-       else
+       else {
+               /*
+                * try to issue requests directly if the hw queue isn't
+                * busy in case of 'none' scheduler, and this way may save
+                * us one extra enqueue & dequeue to sw queue.
+                */
+               if (!hctx->dispatch_busy && !e && !run_queue_async) {
+                       blk_mq_try_issue_list_directly(hctx, list);
+                       if (list_empty(list))
+                               return;
+               }
                blk_mq_insert_requests(hctx, ctx, list);
+       }
 
        blk_mq_run_hw_queue(hctx, run_queue_async);
 }