The per-ofd and per-export brw_stats are not maintained although the proc files still exist (see /proc/fs/lustre/obdfilter//brw_stats and /proc/fs/lustre/obdfilter//exports/*/brw_stats). Since filter_iobuf is now osd_iobuf, down one layer and without access to the export, it would be difficult to restore maintenance of these files.

The per-ofd brw_stats file could be replaced with a symlink to ../../osd-whatever/whoever/brw_stats (as in the patch for LU-2358) but there doesn't seem to be consensus that doing so is the Right Thing.