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. -- Jens Axboe -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
