block: Use pointer to backing_dev_info from request_queue

We will want to have struct backing_dev_info allocated separately from
struct request_queue. As the first step add pointer to backing_dev_info
to request_queue and convert all users touching it. No functional
changes in this patch.

Change-Id: Ib99961747ed2d58cc2f9c0581c66c55a49aaee4b
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jens Axboe <axboe@fb.com>
Git-commit: dc3b17cc8bf21307c7e076e7c778d5db756f7871
Git-repo: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git
[riteshh@codeaurora.org: Resolved minor merge conflicts]
Signed-off-by: Ritesh Harjani <riteshh@codeaurora.org>
diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index 9cc8d7c..f0a2f93 100644
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -75,7 +75,7 @@
 
 static ssize_t queue_ra_show(struct request_queue *q, char *page)
 {
-	unsigned long ra_kb = q->backing_dev_info.ra_pages <<
+	unsigned long ra_kb = q->backing_dev_info->ra_pages <<
 					(PAGE_SHIFT - 10);
 
 	return queue_var_show(ra_kb, (page));
@@ -90,7 +90,7 @@
 	if (ret < 0)
 		return ret;
 
-	q->backing_dev_info.ra_pages = ra_kb >> (PAGE_SHIFT - 10);
+	q->backing_dev_info->ra_pages = ra_kb >> (PAGE_SHIFT - 10);
 
 	return ret;
 }
@@ -627,7 +627,7 @@
 	struct request_queue *q =
 		container_of(kobj, struct request_queue, kobj);
 
-	bdi_exit(&q->backing_dev_info);
+	bdi_exit(q->backing_dev_info);
 	blkcg_exit_queue(q);
 
 	if (q->elevator) {