X-Git-Url: http://drtracing.org/?a=blobdiff_plain;f=block%2Fblk-mq.c;h=7950f8d7c1bb182b25aa9df8d41910941fc0022d;hb=a57821cac6bb6e46abea118e34d0e86444ec1410;hp=5189cb1e478a6b283609006364c01f9f8e31d082;hpb=3b7b3e6ec5f56118046594d3c62469e7d1d0aadd;p=deliverable%2Flinux.git

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 5189cb1e478a..7950f8d7c1bb 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -112,18 +112,22 @@ static void blk_mq_usage_counter_release(struct percpu_ref *ref)
  */
 void blk_mq_freeze_queue(struct request_queue *q)
 {
+	bool freeze;
+
 	spin_lock_irq(q->queue_lock);
-	q->mq_freeze_depth++;
+	freeze = !q->mq_freeze_depth++;
 	spin_unlock_irq(q->queue_lock);
 
-	percpu_ref_kill(&q->mq_usage_counter);
-	blk_mq_run_queues(q, false);
+	if (freeze) {
+		percpu_ref_kill(&q->mq_usage_counter);
+		blk_mq_run_queues(q, false);
+	}
 	wait_event(q->mq_freeze_wq, percpu_ref_is_zero(&q->mq_usage_counter));
 }
 
 static void blk_mq_unfreeze_queue(struct request_queue *q)
 {
-	bool wake = false;
+	bool wake;
 
 	spin_lock_irq(q->queue_lock);
 	wake = !--q->mq_freeze_depth;
@@ -1068,13 +1072,17 @@ static void blk_mq_bio_to_request(struct request *rq, struct bio *bio)
 		blk_account_io_start(rq, 1);
 }
 
+static inline bool hctx_allow_merges(struct blk_mq_hw_ctx *hctx)
+{
+	return (hctx->flags & BLK_MQ_F_SHOULD_MERGE) &&
+		!blk_queue_nomerges(hctx->queue);
+}
+
 static inline bool blk_mq_merge_queue_io(struct blk_mq_hw_ctx *hctx,
 					 struct blk_mq_ctx *ctx,
 					 struct request *rq, struct bio *bio)
 {
-	struct request_queue *q = hctx->queue;
-
-	if (!(hctx->flags & BLK_MQ_F_SHOULD_MERGE)) {
+	if (!hctx_allow_merges(hctx)) {
 		blk_mq_bio_to_request(rq, bio);
 		spin_lock(&ctx->lock);
 insert_rq:
@@ -1082,6 +1090,8 @@ insert_rq:
 		spin_unlock(&ctx->lock);
 		return false;
 	} else {
+		struct request_queue *q = hctx->queue;
+
 		spin_lock(&ctx->lock);
 		if (!blk_mq_attempt_merge(q, ctx, bio)) {
 			blk_mq_bio_to_request(rq, bio);
@@ -1574,7 +1584,7 @@ static int blk_mq_init_hw_queues(struct request_queue *q,
 		hctx->tags = set->tags[i];
 
 		/*
-		 * Allocate space for all possible cpus to avoid allocation in
+		 * Allocate space for all possible cpus to avoid allocation at
 		 * runtime
 		 */
 		hctx->ctxs = kmalloc_node(nr_cpu_ids * sizeof(void *),
@@ -1662,8 +1672,8 @@ static void blk_mq_map_swqueue(struct request_queue *q)
 
 	queue_for_each_hw_ctx(q, hctx, i) {
 		/*
-		 * If not software queues are mapped to this hardware queue,
-		 * disable it and free the request entries
+		 * If no software queues are mapped to this hardware queue,
+		 * disable it and free the request entries.
 		 */
 		if (!hctx->nr_ctx) {
 			struct blk_mq_tag_set *set = q->tag_set;
@@ -1713,14 +1723,10 @@ static void blk_mq_del_queue_tag_set(struct request_queue *q)
 {
 	struct blk_mq_tag_set *set = q->tag_set;
 
-	blk_mq_freeze_queue(q);
-
 	mutex_lock(&set->tag_list_lock);
 	list_del_init(&q->tag_set_list);
 	blk_mq_update_tag_set_depth(set);
 	mutex_unlock(&set->tag_list_lock);
-
-	blk_mq_unfreeze_queue(q);
 }
 
 static void blk_mq_add_queue_tag_set(struct blk_mq_tag_set *set,