> + size = iov_iter_extract_pages(iter, &pages,
> + UINT_MAX - bio->bi_iter.bi_size,
> + nr_pages, gup_flags, &offset);
> if (unlikely(size <= 0))
> + bio_set_cleanup_mode(bio, iter, gup_flags);
This should move out to bio_iov_iter_get_pages and only be called
once.
> +++ b/block/blk-map.c
> @@ -285,24 +285,24 @@ static int bio_map_user_iov(struct request *rq, struct iov_iter *iter,
> gup_flags |= FOLL_PCI_P2PDMA;
>
> while (iov_iter_count(iter)) {
> - struct page **pages, *stack_pages[UIO_FASTIOV];
> + struct page *stack_pages[UIO_FASTIOV];
> + struct page **pages = stack_pages;
> ssize_t bytes;
> size_t offs;
> int npages;
>
> - if (nr_vecs <= ARRAY_SIZE(stack_pages)) {
> - pages = stack_pages;
> - bytes = iov_iter_get_pages(iter, pages, LONG_MAX,
> - nr_vecs, &offs, gup_flags);
> - } else {
> - bytes = iov_iter_get_pages_alloc(iter, &pages,
> - LONG_MAX, &offs, gup_flags);
> - }
> + if (nr_vecs > ARRAY_SIZE(stack_pages))
> + pages = NULL;
> +
> + bytes = iov_iter_extract_pages(iter, &pages, LONG_MAX,
> + nr_vecs, gup_flags, &offs);
> if (unlikely(bytes <= 0)) {
> ret = bytes ? bytes : -EFAULT;
> goto out_unmap;
> }
>
> + bio_set_cleanup_mode(bio, iter, gup_flags);
Same here - one call outside of the loop.
> +static inline void bio_set_cleanup_mode(struct bio *bio, struct iov_iter *iter,
> + unsigned int gup_flags)
> +{
> + unsigned int cleanup_mode;
> +
> + bio_clear_flag(bio, BIO_PAGE_REFFED);
.. and this should not be needed. Instead:
> + cleanup_mode = iov_iter_extract_mode(iter, gup_flags);
> + if (cleanup_mode & FOLL_GET)
> + bio_set_flag(bio, BIO_PAGE_REFFED);
> + if (cleanup_mode & FOLL_PIN)
> + bio_set_flag(bio, BIO_PAGE_PINNED);
We could warn if a not match flag is set here if we really care.
