blk-mq: kill q->mq_map

It's just a pointer to set->mq_map, use that instead. Move the
assignment a bit earlier, so we always know it's valid.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block/blk-mq.c

@@ -2322,7 +2322,7 @@ static void blk_mq_map_swqueue(struct request_queue *q)
 	 * If the cpu isn't present, the cpu is mapped to first hctx.
 	 */
 	for_each_possible_cpu(i) {
-		hctx_idx = q->mq_map[i];
+		hctx_idx = set->mq_map[i];
 		/* unmapped hw queue can be remapped after CPU topo changed */
 		if (!set->tags[hctx_idx] &&
 		    !__blk_mq_alloc_rq_map(set, hctx_idx)) {
@@ -2332,7 +2332,7 @@ static void blk_mq_map_swqueue(struct request_queue *q)
 			 * case, remap the current ctx to hctx[0] which
 			 * is guaranteed to always have tags allocated
 			 */
-			q->mq_map[i] = 0;
+			set->mq_map[i] = 0;
 		}
 
 		ctx = per_cpu_ptr(q->queue_ctx, i);
@@ -2430,8 +2430,6 @@ static void blk_mq_del_queue_tag_set(struct request_queue *q)
 static void blk_mq_add_queue_tag_set(struct blk_mq_tag_set *set,
 				     struct request_queue *q)
 {
-	q->tag_set = set;
-
 	mutex_lock(&set->tag_list_lock);
 
 	/*
@@ -2468,8 +2466,6 @@ void blk_mq_release(struct request_queue *q)
 		kobject_put(&hctx->kobj);
 	}
 
-	q->mq_map = NULL;
-
 	kfree(q->queue_hw_ctx);
 
 	/*
@@ -2589,7 +2585,7 @@ static void blk_mq_realloc_hw_ctxs(struct blk_mq_tag_set *set,
 		int node;
 		struct blk_mq_hw_ctx *hctx;
 
-		node = blk_mq_hw_queue_to_node(q->mq_map, i);
+		node = blk_mq_hw_queue_to_node(set->mq_map, i);
 		/*
 		 * If the hw queue has been mapped to another numa node,
 		 * we need to realloc the hctx. If allocation fails, fallback
@@ -2666,8 +2662,6 @@ struct request_queue *blk_mq_init_allocated_queue(struct blk_mq_tag_set *set,
 	if (!q->queue_hw_ctx)
 		goto err_percpu;
 
-	q->mq_map = set->mq_map;
-
 	blk_mq_realloc_hw_ctxs(set, q);
 	if (!q->nr_hw_queues)
 		goto err_hctxs;
@@ -2676,6 +2670,7 @@ struct request_queue *blk_mq_init_allocated_queue(struct blk_mq_tag_set *set,
 	blk_queue_rq_timeout(q, set->timeout ? set->timeout : 30 * HZ);
 
 	q->nr_queues = nr_cpu_ids;
+	q->tag_set = set;
 
 	q->queue_flags |= QUEUE_FLAG_MQ_DEFAULT;
 

block/blk-mq.h

@@ -75,7 +75,9 @@ extern int blk_mq_hw_queue_to_node(unsigned int *map, unsigned int);
 static inline struct blk_mq_hw_ctx *blk_mq_map_queue(struct request_queue *q,
 		int cpu)
 {
-	return q->queue_hw_ctx[q->mq_map[cpu]];
+	struct blk_mq_tag_set *set = q->tag_set;
+
+	return q->queue_hw_ctx[set->mq_map[cpu]];
 }
 
 /*

include/linux/blkdev.h

@@ -409,8 +409,6 @@ struct request_queue {
 
 	const struct blk_mq_ops	*mq_ops;
 
-	unsigned int		*mq_map;
-
 	/* sw queues */
 	struct blk_mq_ctx __percpu	*queue_ctx;
 	unsigned int		nr_queues;