On Thu, Dec 21 2006, Mike Christie wrote: > Mike Christie wrote: > > Jens Axboe wrote: > >> On Thu, Dec 21 2006, Mike Christie wrote: > >>> Or the block layer code could set up the clone too. elv_next_request > >>> could prep a clone based on the orignal request for the driver then dm > >>> would not have to worry about that part. > >> It really can't, since it doesn't know how to allocate the clone > >> request. I'd rather export this functionality as helpers. > >> > > > > What do you think about dm's plan to break up make_request into a > > mapping function and in to the part the builds the bio into a request. > > This would fit well with them being helpers and being able to allocate > > the request from the correct context. > > > > I see patches for that did not get posted, but I thought Joe and > > Alasdair used to talk about that a lot and in the dm code I think there > > is sill comments about doing it. Maybe the dm comments mentioned the > > merge_fn, but I guess the merge_fn did not fit what they wanted to do or > > something. I think Alasdair talked about this at one of his talks at OLS > > or it was in a proposal for the kernel summit. I can dig up the mail if > > you want. > > > > Ignore that. The problem would be that we may not want to decide which > path to use at map time. Latter part, or both paragraphs? Dipping into ->make_request_fn() for some parts do seem to make sense to me. It'll be cheaper than at potential soft irq time (from elv_next_request()). -- Jens Axboe -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
