blk-mq: kill q->mq_map

to #28991349

commit a8908939af569ce2419f43fd56eeaf003bc3d85d upstream

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: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Reviewed-by: NBart Van Assche <bvanassche@acm.org>
Reviewed-by: NKeith Busch <keith.busch@intel.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>
Signed-off-by: NXiaoguang Wang <xiaoguang.wang@linux.alibaba.com>
Reviewed-by: NJoseph Qi <joseph.qi@linux.alibaba.com>

block/blk-mq.c

@@ -2392,7 +2392,7 @@ 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)) {
@@ -2402,7 +2402,7 @@ 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);
@@ -2500,8 +2500,6 @@ 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);
 
 	/*
@@ -2566,8 +2564,6 @@ void blk_mq_release(struct request_queue *q)
 		kobject_put(&hctx->kobj);
 	}
 
-	q->mq_map = NULL;
-
 	kfree(q->queue_hw_ctx);
 
 	/*
@@ -2652,7 +2648,7 @@ 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
@@ -2728,8 +2724,6 @@ struct request_queue *blk_mq_init_allocated_queue(struct blk_mq_tag_set *set,
 	if (!q->queue_hw_ctx)
 		goto err_sys_init;
 
-	q->mq_map = set->mq_map;
-
 	blk_mq_realloc_hw_ctxs(set, q);
 	if (!q->nr_hw_queues)
 		goto err_hctxs;
@@ -2738,6 +2732,7 @@ 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;
 	if (q->mq_ops->poll)

block/blk-mq.h

@@ -81,7 +81,9 @@ 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

@@ -483,8 +483,6 @@ 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;