[PATCHv2 1/4] block: bio-integrity: directly map user buffers

[Kanchan Joshi]

On 10/27/2023 11:49 PM, Keith Busch wrote:
> +int bio_integrity_map_user(struct bio *bio, void __user *ubuf, unsigned int len,
> +			   u32 seed)
> +{
> +	struct request_queue *q = bdev_get_queue(bio->bi_bdev);
> +	unsigned long offs, align = q->dma_pad_mask | queue_dma_alignment(q);
> +	int ret, direction, nr_vecs, i, j, folios = 0;
> +	struct bio_vec stack_vec[UIO_FASTIOV];
> +	struct bio_vec bv, *bvec = stack_vec;
> +	struct page *stack_pages[UIO_FASTIOV];
> +	struct page **pages = stack_pages;
> +	struct bio_integrity_payload *bip;
> +	struct iov_iter iter;
> +	struct bvec_iter bi;
> +	u32 bytes;
> +
> +	if (bio_integrity(bio))
> +		return -EINVAL;
> +	if (len >> SECTOR_SHIFT > queue_max_hw_sectors(q))
> +		return -E2BIG;
> +
> +	if (bio_data_dir(bio) == READ)
> +		direction = ITER_DEST;
> +	else
> +		direction = ITER_SOURCE;
> +
> +	iov_iter_ubuf(&iter, direction, ubuf, len);
> +	nr_vecs = iov_iter_npages(&iter, BIO_MAX_VECS + 1);
> +	if (nr_vecs > BIO_MAX_VECS)
> +		return -E2BIG;
> +	if (nr_vecs > UIO_FASTIOV) {
> +		bvec = kcalloc(sizeof(*bvec), nr_vecs, GFP_KERNEL);
> +		if (!bvec)
> +			return -ENOMEM;
> +		pages = NULL;
> +	}
> +
> +	bytes = iov_iter_extract_pages(&iter, &pages, len, nr_vecs, 0, &offs);
> +	if (unlikely(bytes < 0)) {
> +		ret =  bytes;
> +		goto free_bvec;
> +	}
> +
> +	for (i = 0; i < nr_vecs; i = j) {
> +		size_t size = min_t(size_t, bytes, PAGE_SIZE - offs);
> +		struct folio *folio = page_folio(pages[i]);
> +
> +		bytes -= size;
> +		for (j = i + 1; j < nr_vecs; j++) {
> +			size_t next = min_t(size_t, PAGE_SIZE, bytes);
> +
> +			if (page_folio(pages[j]) != folio ||
> +			    pages[j] != pages[j - 1] + 1)
> +				break;
> +			unpin_user_page(pages[j]);

Is this unpin correct here?