osd/PrimaryLogPG: fix dirty range of write_full

osd/PrimaryLogPG: fix dirty range of write_full

A write_full operation may implicitly truncate the object down,
hence we need to mark the truncated part as dirty as well since
follow-up randomized writes may still be able to (re)extend the
object size and leave some holes against the truncated part,
which as a result might cause problems during incremental-mode
recovery.

Note that write_update_size_and_usage would reset oi.size
and that's why we move the mark_data_region_dirty call before that.

Signed-off-by: xie xingguo <xie.xingguo@zte.com.cn>