bdi: remove bdi_register_owner

Split out a new bdi_set_owner helper to set the owner, and move the policy
for creating the bdi name back into genhd.c, where it belongs.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block/genhd.c

@@ -840,13 +840,15 @@ static void __device_add_disk(struct device *parent, struct gendisk *disk,
 		disk->flags |= GENHD_FL_SUPPRESS_PARTITION_INFO;
 		disk->flags |= GENHD_FL_NO_PART_SCAN;
 	} else {
+		struct backing_dev_info *bdi = disk->queue->backing_dev_info;
+		struct device *dev = disk_to_dev(disk);
 		int ret;
 
 		/* Register BDI before referencing it from bdev */
-		disk_to_dev(disk)->devt = devt;
-		ret = bdi_register_owner(disk->queue->backing_dev_info,
-						disk_to_dev(disk));
+		dev->devt = devt;
+		ret = bdi_register(bdi, "%u:%u", MAJOR(devt), MINOR(devt));
 		WARN_ON(ret);
+		bdi_set_owner(bdi, dev);
 		blk_register_region(disk_devt(disk), disk->minors, NULL,
 				    exact_match, exact_lock, disk);
 	}

include/linux/backing-dev.h

@@ -33,7 +33,7 @@ int bdi_register(struct backing_dev_info *bdi, const char *fmt, ...);
 __printf(2, 0)
 int bdi_register_va(struct backing_dev_info *bdi, const char *fmt,
 		    va_list args);
-int bdi_register_owner(struct backing_dev_info *bdi, struct device *owner);
+void bdi_set_owner(struct backing_dev_info *bdi, struct device *owner);
 void bdi_unregister(struct backing_dev_info *bdi);
 
 struct backing_dev_info *bdi_alloc_node(gfp_t gfp_mask, int node_id);

mm/backing-dev.c

@@ -977,20 +977,12 @@ int bdi_register(struct backing_dev_info *bdi, const char *fmt, ...)
 }
 EXPORT_SYMBOL(bdi_register);
 
-int bdi_register_owner(struct backing_dev_info *bdi, struct device *owner)
+void bdi_set_owner(struct backing_dev_info *bdi, struct device *owner)
 {
-	int rc;
-
-	rc = bdi_register(bdi, "%u:%u", MAJOR(owner->devt), MINOR(owner->devt));
-	if (rc)
-		return rc;
-	/* Leaking owner reference... */
-	WARN_ON(bdi->owner);
+	WARN_ON_ONCE(bdi->owner);
 	bdi->owner = owner;
 	get_device(owner);
-	return 0;
 }
-EXPORT_SYMBOL(bdi_register_owner);
 
 /*
  * Remove bdi from bdi_list, and ensure that it is no longer visible