Just retrieve the bdi from the disk.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NJan Kara <jack@suse.cz>
Reviewed-by: NJohannes Thumshirn <johannes.thumshirn@wdc.com>
Link: https://lore.kernel.org/r/20210809141744.1203023-6-hch@lst.deSigned-off-by: NJens Axboe <axboe@kernel.dk>