All callers can safely block. Kill the atomic/block argument, and
remove the argument from all callers.
Reviewed-by: NBart Van Assche <Bart.VanAssche@sandisk.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Tested-by: NMing Lei <ming.lei@redhat.com>
Signed-off-by: NJens Axboe <axboe@fb.com>