block: cleanup the lockdep handling in *alloc_disk

Pass the lockdep name to the low-level __blk_alloc_disk helper and
hardcode the name for it given that the number of minors or node_id
are not very useful information.  While this passes a pointless
argument for non-lockdep builds that is not really an issue as
disk allocation is a probe time only slow path.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20210816131910.615153-5-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block/blk-mq.c

@@ -3133,7 +3133,8 @@ struct request_queue *blk_mq_init_queue(struct blk_mq_tag_set *set)
 }
 EXPORT_SYMBOL(blk_mq_init_queue);
 
-struct gendisk *__blk_mq_alloc_disk(struct blk_mq_tag_set *set, void *queuedata)
+struct gendisk *__blk_mq_alloc_disk(struct blk_mq_tag_set *set, void *queuedata,
+		struct lock_class_key *lkclass)
 {
 	struct request_queue *q;
 	struct gendisk *disk;
@@ -3142,7 +3143,7 @@ struct gendisk *__blk_mq_alloc_disk(struct blk_mq_tag_set *set, void *queuedata)
 	if (IS_ERR(q))
 		return ERR_CAST(q);
 
-	disk = __alloc_disk_node(0, set->numa_node);
+	disk = __alloc_disk_node(0, set->numa_node, lkclass);
 	if (!disk) {
 		blk_cleanup_queue(q);
 		return ERR_PTR(-ENOMEM);

block/genhd.c

@@ -1254,7 +1254,8 @@ dev_t blk_lookup_devt(const char *name, int partno)
 	return devt;
 }
 
-struct gendisk *__alloc_disk_node(int minors, int node_id)
+struct gendisk *__alloc_disk_node(int minors, int node_id,
+		struct lock_class_key *lkclass)
 {
 	struct gendisk *disk;
 
@@ -1282,6 +1283,7 @@ struct gendisk *__alloc_disk_node(int minors, int node_id)
 	disk_to_dev(disk)->type = &disk_type;
 	device_initialize(disk_to_dev(disk));
 	inc_diskseq(disk);
+	lockdep_init_map(&disk->lockdep_map, "(bio completion)", lkclass, 0);
 #ifdef CONFIG_BLOCK_HOLDER_DEPRECATED
 	INIT_LIST_HEAD(&disk->slave_bdevs);
 #endif
@@ -1298,7 +1300,7 @@ out_free_disk:
 }
 EXPORT_SYMBOL(__alloc_disk_node);
 
-struct gendisk *__blk_alloc_disk(int node)
+struct gendisk *__blk_alloc_disk(int node, struct lock_class_key *lkclass)
 {
 	struct request_queue *q;
 	struct gendisk *disk;
@@ -1307,7 +1309,7 @@ struct gendisk *__blk_alloc_disk(int node)
 	if (!q)
 		return NULL;
 
-	disk = __alloc_disk_node(0, node);
+	disk = __alloc_disk_node(0, node, lkclass);
 	if (!disk) {
 		blk_cleanup_queue(q);
 		return NULL;

include/linux/blk-mq.h

@@ -432,18 +432,14 @@ enum {
 	((policy & ((1 << BLK_MQ_F_ALLOC_POLICY_BITS) - 1)) \
 		<< BLK_MQ_F_ALLOC_POLICY_START_BIT)
 
+struct gendisk *__blk_mq_alloc_disk(struct blk_mq_tag_set *set, void *queuedata,
+		struct lock_class_key *lkclass);
 #define blk_mq_alloc_disk(set, queuedata)				\
 ({									\
 	static struct lock_class_key __key;				\
-	struct gendisk *__disk = __blk_mq_alloc_disk(set, queuedata);	\
 									\
-	if (!IS_ERR(__disk))						\
+	__blk_mq_alloc_disk(set, queuedata, &__key);			\
-		lockdep_init_map(&__disk->lockdep_map,			\
-			"(bio completion)", &__key, 0);			\
-	__disk;								\
 })
-struct gendisk *__blk_mq_alloc_disk(struct blk_mq_tag_set *set,
-		void *queuedata);
 struct request_queue *blk_mq_init_queue(struct blk_mq_tag_set *);
 int blk_mq_init_allocated_queue(struct blk_mq_tag_set *set,
 		struct request_queue *q);

include/linux/genhd.h

@@ -259,27 +259,21 @@ static inline sector_t get_capacity(struct gendisk *disk)
 int bdev_disk_changed(struct gendisk *disk, bool invalidate);
 void blk_drop_partitions(struct gendisk *disk);
 
-extern struct gendisk *__alloc_disk_node(int minors, int node_id);
+struct gendisk *__alloc_disk_node(int minors, int node_id,
+		struct lock_class_key *lkclass);
 extern void put_disk(struct gendisk *disk);
 
 #define alloc_disk_node(minors, node_id)				\
 ({									\
 	static struct lock_class_key __key;				\
-	const char *__name;						\
-	struct gendisk *__disk;						\
 									\
-	__name = "(gendisk_completion)"#minors"("#node_id")";		\
+	__alloc_disk_node(minors, node_id, &__key);			\
-									\
-	__disk = __alloc_disk_node(minors, node_id);			\
-									\
-	if (__disk)							\
-		lockdep_init_map(&__disk->lockdep_map, __name, &__key, 0); \
-									\
-	__disk;								\
 })
 
 #define alloc_disk(minors) alloc_disk_node(minors, NUMA_NO_NODE)
 
+struct gendisk *__blk_alloc_disk(int node, struct lock_class_key *lkclass);
+
 /**
  * blk_alloc_disk - allocate a gendisk structure
  * @node_id: numa node to allocate on
@@ -291,15 +285,10 @@ extern void put_disk(struct gendisk *disk);
  */
 #define blk_alloc_disk(node_id)						\
 ({									\
-	struct gendisk *__disk = __blk_alloc_disk(node_id);		\
 	static struct lock_class_key __key;				\
 									\
-	if (__disk)							\
+	__blk_alloc_disk(node_id, &__key);				\
-		lockdep_init_map(&__disk->lockdep_map,			\
-			"(bio completion)", &__key, 0);			\
-	__disk;								\
 })
-struct gendisk *__blk_alloc_disk(int node);
 void blk_cleanup_disk(struct gendisk *disk);
 
 int __register_blkdev(unsigned int major, const char *name,