Re: [PATCHv3 1/6] block/bio: remove duplicate append pages code

[Pankaj Raghav <pankydev8@gmail.com>]

On Mon, May 23, 2022 at 02:01:14PM -0700, Keith Busch wrote:
> From: Keith Busch <kbusch@kernel.org>
> 
> The getting pages setup for zone append and normal IO are identical. Use
> common code for each.
> 
> Signed-off-by: Keith Busch <kbusch@kernel.org>
> +
> +static int bio_iov_add_zone_append_page(struct bio *bio, struct page *page,
> +		unsigned int len, unsigned int offset)
> +{
> +	struct request_queue *q = bdev_get_queue(bio->bi_bdev);
> +	bool same_page = false;
> +
> +	if (bio_add_hw_page(q, bio, page, len, offset,
> +			queue_max_zone_append_sectors(q), &same_page) != len)
> +		return -EINVAL;
> +	if (same_page)
> +		put_page(page);
> +	return 0;
> +}
> +
>  
> -static int __bio_iov_append_get_pages(struct bio *bio, struct iov_iter *iter)
> -{
> -	unsigned short nr_pages = bio->bi_max_vecs - bio->bi_vcnt;
> -	unsigned short entries_left = bio->bi_max_vecs - bio->bi_vcnt;
> -	struct request_queue *q = bdev_get_queue(bio->bi_bdev);
> -	unsigned int max_append_sectors = queue_max_zone_append_sectors(q);
> -	struct bio_vec *bv = bio->bi_io_vec + bio->bi_vcnt;
> -	struct page **pages = (struct page **)bv;
> -	ssize_t size, left;
> -	unsigned len, i;
> -	size_t offset;
> -	int ret = 0;
> -

> -	if (WARN_ON_ONCE(!max_append_sectors))
> -		return 0;
I don't see this check in the append path. Should it be added in
bio_iov_add_zone_append_page() function?
> -
> -	/*
> -	 * Move page array up in the allocated memory for the bio vecs as far as
> -	 * possible so that we can start filling biovecs from the beginning
> -	 * without overwriting the temporary page array.
> -	 */
> -	BUILD_BUG_ON(PAGE_PTRS_PER_BVEC < 2);
> -	pages += entries_left * (PAGE_PTRS_PER_BVEC - 1);
> -
> -	size = iov_iter_get_pages(iter, pages, LONG_MAX, nr_pages, &offset);
> -	if (unlikely(size <= 0))

-- 
Pankaj Raghav