On 12/4/18 7:55 AM, Christoph Hellwig wrote: > On Fri, Nov 30, 2018 at 07:21:02PM +0000, Al Viro wrote: >> On Fri, Nov 30, 2018 at 09:56:43AM -0700, Jens Axboe wrote: >>> For an ITER_KVEC, we can just iterate the iov and add the pages >>> to the bio directly. >> >>> + page = virt_to_page(kv->iov_base); >>> + size = bio_add_page(bio, page, kv->iov_len, >>> + offset_in_page(kv->iov_base)); >> >> Who said that you *can* do virt_to_page() on those? E.g. vmalloc()'ed >> addresses are fine for ITER_KVEC, etc. > > In this particular case the caller it seems the callers knows what kind > of pages we have, but we need to properly document this at the very least. > > Note that in the completely generic case iov_base could also point to > memory without a struct page at all (e.g. ioremap()ed memory). That's why I went to ITER_BVEC instead, that's much saner for this use case. -- Jens Axboe
