blk-mq: cleanup __blk_mq_sched_dispatch_requests

__blk_mq_sched_dispatch_requests currently has duplicated logic
for the cases where requests are on the hctx dispatch list or not.
Merge the two with a new need_dispatch variable and remove a few
pointless local variables.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Link: https://lore.kernel.org/r/20230413060651.694656-2-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c
index f90fc42..67c95f3 100644 (file)
--- a/block/blk-mq-sched.c
+++ b/block/blk-mq-sched.c
@@ -269,9 +269,7 @@ static int blk_mq_do_dispatch_ctx(struct blk_mq_hw_ctx *hctx)
 
 static int __blk_mq_sched_dispatch_requests(struct blk_mq_hw_ctx *hctx)
 {
-       struct request_queue *q = hctx->queue;
-       const bool has_sched = q->elevator;
-       int ret = 0;
+       bool need_dispatch = false;
        LIST_HEAD(rq_list);
 
        /*
@@ -300,23 +298,22 @@ static int __blk_mq_sched_dispatch_requests(struct blk_mq_hw_ctx *hctx)
         */
        if (!list_empty(&rq_list)) {
                blk_mq_sched_mark_restart_hctx(hctx);
-               if (blk_mq_dispatch_rq_list(hctx, &rq_list, 0)) {
-                       if (has_sched)
-                               ret = blk_mq_do_dispatch_sched(hctx);
-                       else
-                               ret = blk_mq_do_dispatch_ctx(hctx);
-               }
-       } else if (has_sched) {
-               ret = blk_mq_do_dispatch_sched(hctx);
-       } else if (hctx->dispatch_busy) {
-               /* dequeue request one by one from sw queue if queue is busy */
-               ret = blk_mq_do_dispatch_ctx(hctx);
+               if (!blk_mq_dispatch_rq_list(hctx, &rq_list, 0))
+                       return 0;
+               need_dispatch = true;
        } else {
-               blk_mq_flush_busy_ctxs(hctx, &rq_list);
-               blk_mq_dispatch_rq_list(hctx, &rq_list, 0);
+               need_dispatch = hctx->dispatch_busy;
        }
 
-       return ret;
+       if (hctx->queue->elevator)
+               return blk_mq_do_dispatch_sched(hctx);
+
+       /* dequeue request one by one from sw queue if queue is busy */
+       if (need_dispatch)
+               return blk_mq_do_dispatch_ctx(hctx);
+       blk_mq_flush_busy_ctxs(hctx, &rq_list);
+       blk_mq_dispatch_rq_list(hctx, &rq_list, 0);
+       return 0;
 }
 
 void blk_mq_sched_dispatch_requests(struct blk_mq_hw_ctx *hctx)