1 files changed, 54 insertions, 49 deletions

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 9690f4f8de7e..af4dc8227954 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -1792,78 +1792,83 @@ static blk_status_t __blk_mq_issue_directly(struct blk_mq_hw_ctx *hctx,
         return ret;
 }
 
-static blk_status_t __blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
+static blk_status_t blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
                                                 struct request *rq,
                                                 blk_qc_t *cookie,
-                                                bool bypass_insert, bool last)
+                                                bool bypass, bool last)
 {
         struct request_queue *q = rq->q;
         bool run_queue = true;
+        blk_status_t ret = BLK_STS_RESOURCE;
+        int srcu_idx;
+        bool force = false;
 
+        hctx_lock(hctx, &srcu_idx);
         /*
-         * RCU or SRCU read lock is needed before checking quiesced flag.
+         * hctx_lock is needed before checking quiesced flag.
          *
-         * When queue is stopped or quiesced, ignore 'bypass_insert' from
-         * blk_mq_request_issue_directly(), and return BLK_STS_OK to caller,
-         * and avoid driver to try to dispatch again.
+         * When queue is stopped or quiesced, ignore 'bypass', insert
+         * and return BLK_STS_OK to caller, and avoid driver to try to
+         * dispatch again.
          */
-        if (blk_mq_hctx_stopped(hctx) || blk_queue_quiesced(q)) {
+        if (unlikely(blk_mq_hctx_stopped(hctx) || blk_queue_quiesced(q))) {
                 run_queue = false;
-                bypass_insert = false;
-                goto insert;
+                bypass = false;
+                goto out_unlock;
         }
 
-        if (q->elevator && !bypass_insert)
-                goto insert;
+        if (unlikely(q->elevator && !bypass))
+                goto out_unlock;
 
         if (!blk_mq_get_dispatch_budget(hctx))
-                goto insert;
+                goto out_unlock;
 
         if (!blk_mq_get_driver_tag(rq)) {
                 blk_mq_put_dispatch_budget(hctx);
-                goto insert;
+                goto out_unlock;
         }
 
-        return __blk_mq_issue_directly(hctx, rq, cookie, last);
-insert:
-        if (bypass_insert)
-                return BLK_STS_RESOURCE;
-
-        blk_mq_request_bypass_insert(rq, run_queue);
-        return BLK_STS_OK;
-}
-
-static void blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
-                struct request *rq, blk_qc_t *cookie)
-{
-        blk_status_t ret;
-        int srcu_idx;
-
-        might_sleep_if(hctx->flags & BLK_MQ_F_BLOCKING);
-
-        hctx_lock(hctx, &srcu_idx);
-
-        ret = __blk_mq_try_issue_directly(hctx, rq, cookie, false, true);
-        if (ret == BLK_STS_RESOURCE || ret == BLK_STS_DEV_RESOURCE)
-                blk_mq_request_bypass_insert(rq, true);
-        else if (ret != BLK_STS_OK)
-                blk_mq_end_request(rq, ret);
-
+        /*
+         * Always add a request that has been through
+         *.queue_rq() to the hardware dispatch list.
+         */
+        force = true;
+        ret = __blk_mq_issue_directly(hctx, rq, cookie, last);
+out_unlock:
         hctx_unlock(hctx, srcu_idx);
+        switch (ret) {
+        case BLK_STS_OK:
+                break;
+        case BLK_STS_DEV_RESOURCE:
+        case BLK_STS_RESOURCE:
+                if (force) {
+                        blk_mq_request_bypass_insert(rq, run_queue);
+                        /*
+                         * We have to return BLK_STS_OK for the DM
+                         * to avoid livelock. Otherwise, we return
+                         * the real result to indicate whether the
+                         * request is direct-issued successfully.
+                         */
+                        ret = bypass ? BLK_STS_OK : ret;
+                } else if (!bypass) {
+                        blk_mq_sched_insert_request(rq, false,
+                                                    run_queue, false);
+                }
+                break;
+        default:
+                if (!bypass)
+                        blk_mq_end_request(rq, ret);
+                break;
+        }
+
+        return ret;
 }
 
 blk_status_t blk_mq_request_issue_directly(struct request *rq, bool last)
 {
-        blk_status_t ret;
-        int srcu_idx;
-        blk_qc_t unused_cookie;
-        struct blk_mq_hw_ctx *hctx = rq->mq_hctx;
+        blk_qc_t unused;
 
-        hctx_lock(hctx, &srcu_idx);
-        ret = __blk_mq_try_issue_directly(hctx, rq, &unused_cookie, true, last);
-        hctx_unlock(hctx, srcu_idx);
-
-        return ret;
+        return blk_mq_try_issue_directly(rq->mq_hctx, rq, &unused, true, last);
 }
 
 void blk_mq_try_issue_list_directly(struct blk_mq_hw_ctx *hctx,
@@ -2004,13 +2009,13 @@ static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio)
                 if (same_queue_rq) {
                         data.hctx = same_queue_rq->mq_hctx;
                         blk_mq_try_issue_directly(data.hctx, same_queue_rq,
-                                        &cookie);
+                                        &cookie, false, true);
                 }
         } else if ((q->nr_hw_queues > 1 && is_sync) || (!q->elevator &&
                         !data.hctx->dispatch_busy)) {
                 blk_mq_put_ctx(data.ctx);
                 blk_mq_bio_to_request(rq, bio);
-                blk_mq_try_issue_directly(data.hctx, rq, &cookie);
+                blk_mq_try_issue_directly(data.hctx, rq, &cookie, false, true);
         } else {
                 blk_mq_put_ctx(data.ctx);
                 blk_mq_bio_to_request(rq, bio);