On Thu, Jan 12, 2023 at 01:49:14PM -0800, Bart Van Assche wrote: > I'm not sure that we still need the double copy in the sg driver. It seems > obscure to me that there is user space software that relies on finding > "0xec" in bytes not originating from a SCSI device. Additionally, SCSI > drivers that do not support residuals should be something from the past. > > Others may be better qualified to comment on this topic. Yeah. And that weird (ab)use of blk_rq_map_user_iov into preallocated pages in sg has been a constant source of pain. I'd be very happy to make it match the generic SG_IO implementation and either do get_user_pages or the normal bounce buffering implemented in the common code.
