Re: [PATCH v13 01/42] block: add bio_add_zone_append_page

[Johannes Thumshirn <Johannes.Thumshirn@wdc.com>]

On 22/01/2021 07:22, Naohiro Aota wrote:
> From: Johannes Thumshirn <johannes.thumshirn@wdc.com>
> 
> Add bio_add_zone_append_page(), a wrapper around bio_add_hw_page() which
> is intended to be used by file systems that directly add pages to a bio
> instead of using bio_iov_iter_get_pages().
> 
> Cc: Jens Axboe <axboe@kernel.dk>
> Reviewed-by: Christoph Hellwig <hch@lst.de>
> Reviewed-by: Josef Bacik <josef@toxicpanda.com>
> Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>




Jens ping?


> ---
>  block/bio.c         | 33 +++++++++++++++++++++++++++++++++
>  include/linux/bio.h |  2 ++
>  2 files changed, 35 insertions(+)
> 
> diff --git a/block/bio.c b/block/bio.c
> index 1f2cc1fbe283..2f21d2958b60 100644
> --- a/block/bio.c
> +++ b/block/bio.c
> @@ -851,6 +851,39 @@ int bio_add_pc_page(struct request_queue *q, struct bio *bio,
>  }
>  EXPORT_SYMBOL(bio_add_pc_page);
>  
> +/**
> + * bio_add_zone_append_page - attempt to add page to zone-append bio
> + * @bio: destination bio
> + * @page: page to add
> + * @len: vec entry length
> + * @offset: vec entry offset
> + *
> + * Attempt to add a page to the bio_vec maplist of a bio that will be submitted
> + * for a zone-append request. This can fail for a number of reasons, such as the
> + * bio being full or the target block device is not a zoned block device or
> + * other limitations of the target block device. The target block device must
> + * allow bio's up to PAGE_SIZE, so it is always possible to add a single page
> + * to an empty bio.
> + *
> + * Returns: number of bytes added to the bio, or 0 in case of a failure.
> + */
> +int bio_add_zone_append_page(struct bio *bio, struct page *page,
> +			     unsigned int len, unsigned int offset)
> +{
> +	struct request_queue *q = bio->bi_disk->queue;
> +	bool same_page = false;
> +
> +	if (WARN_ON_ONCE(bio_op(bio) != REQ_OP_ZONE_APPEND))
> +		return 0;
> +
> +	if (WARN_ON_ONCE(!blk_queue_is_zoned(q)))
> +		return 0;
> +
> +	return bio_add_hw_page(q, bio, page, len, offset,
> +			       queue_max_zone_append_sectors(q), &same_page);
> +}
> +EXPORT_SYMBOL_GPL(bio_add_zone_append_page);
> +
>  /**
>   * __bio_try_merge_page - try appending data to an existing bvec.
>   * @bio: destination bio
> diff --git a/include/linux/bio.h b/include/linux/bio.h
> index 1edda614f7ce..de62911473bb 100644
> --- a/include/linux/bio.h
> +++ b/include/linux/bio.h
> @@ -455,6 +455,8 @@ void bio_chain(struct bio *, struct bio *);
>  extern int bio_add_page(struct bio *, struct page *, unsigned int,unsigned int);
>  extern int bio_add_pc_page(struct request_queue *, struct bio *, struct page *,
>  			   unsigned int, unsigned int);
> +int bio_add_zone_append_page(struct bio *bio, struct page *page,
> +			     unsigned int len, unsigned int offset);
>  bool __bio_try_merge_page(struct bio *bio, struct page *page,
>  		unsigned int len, unsigned int off, bool *same_page);
>  void __bio_add_page(struct bio *bio, struct page *page,
>