1 files changed, 9 insertions, 2 deletions

diff --git a/block/blk-tag.c b/block/blk-tag.c
index cc345e1d8d4e..3f33d8672268 100644
--- a/block/blk-tag.c
+++ b/block/blk-tag.c
@@ -348,9 +348,16 @@ int blk_queue_start_tag(struct request_queue *q, struct request *rq)
          */
         max_depth = bqt->max_depth;
         if (!rq_is_sync(rq) && max_depth > 1) {
-                max_depth -= 2;
-                if (!max_depth)
+                switch (max_depth) {
+                case 2:
                         max_depth = 1;
+                        break;
+                case 3:
+                        max_depth = 2;
+                        break;
+                default:
+                        max_depth -= 2;
+                }
                 if (q->in_flight[BLK_RW_ASYNC] > max_depth)
                         return 1;
         }