block: add queue_to_disk() to get gendisk from request_queue

Sometimes we need to get the corresponding gendisk from request_queue.

It is preferred that block drivers store private data in
gendisk->private_data rather than request_queue->queuedata, e.g. see:
commit c4a59c4e5db3 ("dm: stop using ->queuedata").

So if only request_queue is given, we need to get its corresponding
gendisk to get the private data stored in that gendisk.

Reviewed-by: Hannes Reinecke <[email protected]>
Reviewed-by: Mike Snitzer <[email protected]>
Signed-off-by: Jeffle Xu <[email protected]>
Signed-off-by: Ming Lei <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>

1 files changed, 2 insertions, 0 deletions

diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index d5d320da51f8..30d2090583ad 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -689,6 +689,8 @@ static inline bool blk_account_rq(struct request *rq)
 	dma_map_page_attrs(dev, (bv)->bv_page, (bv)->bv_offset, (bv)->bv_len, \
 	(dir), (attrs))
 
+#define queue_to_disk(q)	(dev_to_disk(kobj_to_dev((q)->kobj.parent)))
+
 static inline bool queue_is_mq(struct request_queue *q)
 {
 	return q->mq_ops;