This function was moved from core block code and is way to generic.
Fold it into the only caller and simplify it based on the actually
passed arguments.
Acked-by: NTejun Heo <tj@kernel.org>
Acked-by: NPaolo Valente <paolo.valente@linaro.org>
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJens Axboe <axboe@kernel.dk>