On Wed, 11 Feb 2009 11:15:53 +0200 Boaz Harrosh <bharrosh@xxxxxxxxxxx> wrote: > I spoke too soon. There is one more place that uses blk_rq_append_bio, that is > the place that adds the read/write bio that is received in osd_req_write/read. > The reason I receive a bio at these is because mainly I need a way to > accept struct page* arrays, as well as kernel & user pointers. A bio is a nice The API using an array of pointers to page can handle everything. So why do the users of ULD (some rare file systems, I guess), osd initiator, need to build bios and pass them? > general carrier for any type of memory. Given a bio at hand there are no ways > left to prepare a request from it save the FS generic_make_request() route. > > I was thinking of using struct sg_iovec* at one stage but they look very > scary when used with page*, and mapping a page to a pointer but not doing > cache sync and all that jazz. A bio is a very nice carrier of a scatter-gather > list of memory. It has all the API for any needs. blk_rq_append_bio() was the last > way to associate a bio with a request. (except for privileged block-filesystems) We need to remove the usage of blk_rq_append_bio() in scsi. > So the first thing we have to decide is what API we need at read/write > today there is: You are talking about the API for osd file systems (or something related with osd), right? If so, I think that you can do whatever you want to do now. You can make a mistake since it's in-kernel API. > void osd_req_read(struct osd_request *or, > const struct osd_obj_id *, struct bio *data_in, u64 offset); > > in exofs I use these two: > > int osd_req_read_kern(struct osd_request *or, > const struct osd_obj_id *obj, u64 offset, void *buff, u64 len); > int osd_req_read_pages(struct osd_request *or, > const struct osd_obj_id *, u64 offset, u64 length, > struct page **pages, int page_count); > As I wrote above, if you have an interface handling 'struct page **pages', then there should be ok. -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
