On Thu, Jun 11 2009, Jeff Moyer wrote: > Jens Axboe <jens.axboe@xxxxxxxxxx> writes: > > > On Thu, Jun 11 2009, Kiyoshi Ueda wrote: > >> Hi Jens, > >> > >> This patch adds the following 2 interfaces for request-stacking drivers: > >> > >> - blk_rq_prep_clone(struct request *clone, struct request *orig, > >> struct bio_set *bs, gfp_t gfp_mask, > >> int (*bio_ctr)(struct bio *, struct bio*, void *), > >> void *data) > >> * Clones bios in the original request to the clone request > >> (bio_ctr is called for each cloned bios.) > >> * Copies attributes of the original request to the clone request. > >> The actual data parts (e.g. ->cmd, ->buffer, ->sense) are not > >> copied. > >> > >> - blk_rq_unprep_clone(struct request *clone) > >> * Frees cloned bios from the clone request. > >> > >> Request stacking drivers (e.g. request-based dm) need to make a clone > >> request for a submitted request and dispatch it to other devices. > >> > >> To allocate request for the clone, request stacking drivers may not > >> be able to use blk_get_request() because the allocation may be done > >> in an irq-disabled context. > >> So blk_rq_prep_clone() takes a request allocated by the caller > >> as an argument. > >> > >> For each clone bio in the clone request, request stacking drivers > >> should be able to set up their own completion handler. > >> So blk_rq_prep_clone() takes a callback function which is called > >> for each clone bio, and a pointer for private data which is passed > >> to the callback. > >> > >> NOTE: > >> blk_rq_prep_clone() doesn't copy any actual data of the original > >> request. Pages are shared between original bios and cloned bios. > >> So caller must not complete the original request before the clone > >> request. > > > > This looks good to me now, I've applied it. > > Is blk_rq_unprep_clone really the best name? > ^^^^^^ Probably not, but I'm not very good at coming up with elegant names. Your email should have included a new suggestion :-) FWIW, I don't think the name is THAT bad... -- Jens Axboe -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
