On 09/04/2020 05:38, Ming Lei wrote: > On Wed, Apr 08, 2020 at 10:11:19PM -0400, Tejun Heo wrote: >> On Thu, Apr 09, 2020 at 09:44:06AM +0800, Ming Lei wrote: >>> Almost all __blk_mq_end_request() follow blk_update_request(), so the >>> completed bytes can be passed to __blk_mq_end_request(), then we can >>> avoid to introduce this field. >> >> But on some drivers blk_update_request() may be called multiple times before >> __blk_mq_end_request() is called and what's needed here is the total number of >> bytes in the whole request, not just in the final completion. > > OK. > > Another choice might be to record request bytes in rq's payload > when calling .queue_rq() only for these drivers. > >> >>> Also there is just 20 callers of __blk_mq_end_request(), looks this kind >>> of change shouldn't be too big. >> >> This would work iff we get rid of partial completions and if we get rid of >> partial completions, we might as well stop exposing blk_update_request() and >> __blk_mq_end_request(). > > Indeed, we can store the completed bytes in request payload, so looks killing > partial completion shouldn't be too hard. struct request already has such field (see @stats_sectors) because of the same root-cause. I'd prefer killing it as well by following Ming's way, but otherwise it could be easily adopted. -- Pavel Begunkov
