Merge branch 'for-4.4/core' into for-next

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 9e6922ded60a9327f19109cd724124009e2f595c..70819b7b021161a4a806ac1dd1c191544061d340 100644 (file)
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -1673,7 +1673,7 @@ static int blk_mq_init_hctx(struct request_queue *q,
        INIT_LIST_HEAD(&hctx->dispatch);
        hctx->queue = q;
        hctx->queue_num = hctx_idx;
-       hctx->flags = set->flags;
+       hctx->flags = set->flags & ~BLK_MQ_F_TAG_SHARED;
 
        blk_mq_init_cpu_notifier(&hctx->cpu_notifier,
                                        blk_mq_hctx_notify, hctx);
@@ -1860,27 +1860,26 @@ static void blk_mq_map_swqueue(struct request_queue *q,
        }
 }
 
-static void blk_mq_update_tag_set_depth(struct blk_mq_tag_set *set)
+static void queue_set_hctx_shared(struct request_queue *q, bool shared)
 {
        struct blk_mq_hw_ctx *hctx;
-       struct request_queue *q;
-       bool shared;
        int i;
 
-       if (set->tag_list.next == set->tag_list.prev)
-               shared = false;
-       else
-               shared = true;
+       queue_for_each_hw_ctx(q, hctx, i) {
+               if (shared)
+                       hctx->flags |= BLK_MQ_F_TAG_SHARED;
+               else
+                       hctx->flags &= ~BLK_MQ_F_TAG_SHARED;
+       }
+}
+
+static void blk_mq_update_tag_set_depth(struct blk_mq_tag_set *set, bool shared)
+{
+       struct request_queue *q;
 
        list_for_each_entry(q, &set->tag_list, tag_set_list) {
                blk_mq_freeze_queue(q);
-
-               queue_for_each_hw_ctx(q, hctx, i) {
-                       if (shared)
-                               hctx->flags |= BLK_MQ_F_TAG_SHARED;
-                       else
-                               hctx->flags &= ~BLK_MQ_F_TAG_SHARED;
-               }
+               queue_set_hctx_shared(q, shared);
                blk_mq_unfreeze_queue(q);
        }
 }
@@ -1891,7 +1890,12 @@ static void blk_mq_del_queue_tag_set(struct request_queue *q)
 
        mutex_lock(&set->tag_list_lock);
        list_del_init(&q->tag_set_list);
-       blk_mq_update_tag_set_depth(set);
+       if (list_is_singular(&set->tag_list)) {
+               /* just transitioned to unshared */
+               set->flags &= ~BLK_MQ_F_TAG_SHARED;
+               /* update existing queue */
+               blk_mq_update_tag_set_depth(set, false);
+       }
        mutex_unlock(&set->tag_list_lock);
 }
 
@@ -1901,8 +1905,17 @@ static void blk_mq_add_queue_tag_set(struct blk_mq_tag_set *set,
        q->tag_set = set;
 
        mutex_lock(&set->tag_list_lock);
+
+       /* Check to see if we're transitioning to shared (from 1 to 2 queues). */
+       if (!list_empty(&set->tag_list) && !(set->flags & BLK_MQ_F_TAG_SHARED)) {
+               set->flags |= BLK_MQ_F_TAG_SHARED;
+               /* update existing queue */
+               blk_mq_update_tag_set_depth(set, true);
+       }
+       if (set->flags & BLK_MQ_F_TAG_SHARED)
+               queue_set_hctx_shared(q, true);
        list_add_tail(&q->tag_set_list, &set->tag_list);
-       blk_mq_update_tag_set_depth(set);
+
        mutex_unlock(&set->tag_list_lock);
 }