The long if/else chain obsfucates the actual logic.  Tidy it up to be
more structured.  Also drop the whole argument, as it can be trivially
derived from bdev using bdev_whole, and having the bdev_whole in the
function makes it easier to follow.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Acked-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Link: https://lore.kernel.org/r/20230601094459.1350643-3-hch@lst.de


Signed-off-by: Jens Axboe <axboe@kernel.dk>