blk-mq: punt failed direct issue to dispatch list

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

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 0506b7103bf537521b618234afd7002fc3eda56b..52d41d92555e4829dabee692f4cc47679503c785 100644 (file)
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -1778,15 +1778,6 @@ static blk_status_t __blk_mq_issue_directly(struct blk_mq_hw_ctx *hctx,
                break;
        case BLK_STS_RESOURCE:
        case BLK_STS_DEV_RESOURCE:
-               /*
-                * If direct dispatch fails, we cannot allow any merging on
-                * this IO. Drivers (like SCSI) may have set up permanent state
-                * for this request, like SG tables and mappings, and if we
-                * merge to it later on then we'll still only do IO to the
-                * original part.
-                */
-               rq->cmd_flags |= REQ_NOMERGE;
-
                blk_mq_update_dispatch_busy(hctx, true);
                __blk_mq_requeue_request(rq);
                break;
@@ -1799,18 +1790,6 @@ static blk_status_t __blk_mq_issue_directly(struct blk_mq_hw_ctx *hctx,
        return ret;
 }
 
-/*
- * Don't allow direct dispatch of anything but regular reads/writes,
- * as some of the other commands can potentially share request space
- * with data we need for the IO scheduler. If we attempt a direct dispatch
- * on those and fail, we can't safely add it to the scheduler afterwards
- * without potentially overwriting data that the driver has already written.
- */
-static bool blk_rq_can_direct_dispatch(struct request *rq)
-{
-       return req_op(rq) == REQ_OP_READ || req_op(rq) == REQ_OP_WRITE;
-}
-
 static blk_status_t __blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
                                                struct request *rq,
                                                blk_qc_t *cookie,
@@ -1832,7 +1811,7 @@ static blk_status_t __blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
                goto insert;
        }
 
-       if (!blk_rq_can_direct_dispatch(rq) || (q->elevator && !bypass_insert))
+       if (q->elevator && !bypass_insert)
                goto insert;
 
        if (!blk_mq_get_dispatch_budget(hctx))
@@ -1848,7 +1827,7 @@ insert:
        if (bypass_insert)
                return BLK_STS_RESOURCE;
 
-       blk_mq_sched_insert_request(rq, false, run_queue, false);
+       blk_mq_request_bypass_insert(rq, run_queue);
        return BLK_STS_OK;
 }
 
@@ -1864,7 +1843,7 @@ static void blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
 
        ret = __blk_mq_try_issue_directly(hctx, rq, cookie, false);
        if (ret == BLK_STS_RESOURCE || ret == BLK_STS_DEV_RESOURCE)
-               blk_mq_sched_insert_request(rq, false, true, false);
+               blk_mq_request_bypass_insert(rq, true);
        else if (ret != BLK_STS_OK)
                blk_mq_end_request(rq, ret);
 
@@ -1894,15 +1873,13 @@ void blk_mq_try_issue_list_directly(struct blk_mq_hw_ctx *hctx,
                struct request *rq = list_first_entry(list, struct request,
                                queuelist);
 
-               if (!blk_rq_can_direct_dispatch(rq))
-                       break;
-
                list_del_init(&rq->queuelist);
                ret = blk_mq_request_issue_directly(rq);
                if (ret != BLK_STS_OK) {
                        if (ret == BLK_STS_RESOURCE ||
                                        ret == BLK_STS_DEV_RESOURCE) {
-                               list_add(&rq->queuelist, list);
+                               blk_mq_request_bypass_insert(rq,
+                                                       list_empty(list));
                                break;
                        }
                        blk_mq_end_request(rq, ret);