On Mon, Mar 14, 2022 at 02:12:34PM -0600, Jens Axboe wrote: > > * Add WARN_ON_ONCE() on blkg mismatch in ioc_rqos_merge() so that we can > > easily notice similar failures in the future. > > > > * Make sure iocost enable/disable transitions only happen when iocost is > > actually enabled / disabled. > > Is there really no better way to do this than add a lot of expensive > checks to the fast path? > > Even just inverting the checks so that > > if (req->bio->bi_blkg != bio->bi_blkg) > ... > > is checked first would seem a lot saner. > > In any case, since this isn't a new regression, I'd feel a lot better > deferring it to 5.18. As discussed, the only risk of removing the disable/enable switch and always testing is ruining some merges for cases where blkcg is enabled but no control is applied, which shouldn't be a big problem. I'll redo the patch. Thanks. -- tejun
