remove an obsolute comment.
fix typo.
add walb device assemble parameters.
make n_pack_bulk and n_io_bulk variable.
walbctl: support n_pack_bulk/n_io_bulk option for create_wdev command.
add module parameter is_sort_data_io.
notification print.
a bit change of flush forcing policy.
set is_sort_data_io=1 default.