Hi Kiyoshi, Kiyoshi Ueda wrote: > Hi Hannes, > > On Mon, 03 Mar 2008 17:24:50 +0100, Hannes Reinecke wrote: >> Hi Kiyoshi, >> >> Kiyoshi Ueda wrote: >>> This patch adds ->complete_io() hook for request stacking. >>> Request stacking drivers (such as request-based dm) can set >>> a callback for completion. >>> (The hook is not called in blk_end_io(), since request-based dm uses >>> it for clone completion in the following appendix patches.) >>> >> [ .. ] >> I would rather have rq->complete_io() to be pointing to blk_end_io in the >> default case, this way rq->complete_io() would always be valid and we >> would be saving us the if() clause. > > Thank you for the comment. > > I'm thinking about an idea come from Mike and Jens after the session > at LSF'08: > o stacking driver clones both bio and request and uses > bio->bi_end_io and rq->end_io > o stacking driver uses blk_complete_request() in rq->end_io > so that stacking driver can work without queue lock > With this idea, we don't need to add the new hook to request, > and we can use request stacking on drivers using __blk_end_request(). > Huh? I can't really imagine how this should work. If you start using bio->bi_end_io() for stacking usage you'll end up with doing weird thing with the bios ... Can you elaborate a bit more here? > Currently, I'm trying to convert request-based dm to use the idea above. > I'll post the new version as a RFC in the near future. > Oh, cool. Looking forward to it. Cheers, Hannes -- Dr. Hannes Reinecke zSeries & Storage hare@xxxxxxx +49 911 74053 688 SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg GF: Markus Rex, HRB 16746 (AG Nürnberg) -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
