[PATCH V9 1/9] block: export bio_add_hw_pages()

[Damien Le Moal]

On 2021/01/12 13:26, Chaitanya Kulkarni wrote:
> To implement the NVMe Zone Append command on the NVMeOF target side for
> generic Zoned Block Devices with NVMe Zoned Namespaces interface, we
> need to build the bios with hardware limitations, i.e. we use
> bio_add_hw_page() with queue_max_zone_append_sectors() instead of
> bio_add_page().
> 
> Without this API being exported NVMeOF target will require to use
> bio_add_hw_page() caller bio_iov_iter_get_pages(). That results in
> extra work which is inefficient.
> 
> Export the API so that NVMeOF ZBD over ZNS backend can use it to build
> Zone Append bios.
> 
> Signed-off-by: Chaitanya Kulkarni <chaitanya.kulkarni at wdc.com>
> ---
>  block/bio.c            | 1 +
>  block/blk.h            | 4 ----
>  include/linux/blkdev.h | 4 ++++
>  3 files changed, 5 insertions(+), 4 deletions(-)
> 
> diff --git a/block/bio.c b/block/bio.c
> index 1f2cc1fbe283..5cbd56b54f98 100644
> --- a/block/bio.c
> +++ b/block/bio.c
> @@ -826,6 +826,7 @@ int bio_add_hw_page(struct request_queue *q, struct bio *bio,
>  	bio->bi_iter.bi_size += len;
>  	return len;
>  }
> +EXPORT_SYMBOL(bio_add_hw_page);
>  
>  /**
>   * bio_add_pc_page	- attempt to add page to passthrough bio
> diff --git a/block/blk.h b/block/blk.h
> index 7550364c326c..200030b2d74f 100644
> --- a/block/blk.h
> +++ b/block/blk.h
> @@ -351,8 +351,4 @@ int bdev_resize_partition(struct block_device *bdev, int partno,
>  		sector_t start, sector_t length);
>  int disk_expand_part_tbl(struct gendisk *disk, int target);
>  
> -int bio_add_hw_page(struct request_queue *q, struct bio *bio,
> -		struct page *page, unsigned int len, unsigned int offset,
> -		unsigned int max_sectors, bool *same_page);
> -
>  #endif /* BLK_INTERNAL_H */
> diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
> index 070de09425ad..028ccc9bdf8d 100644
> --- a/include/linux/blkdev.h
> +++ b/include/linux/blkdev.h
> @@ -2005,6 +2005,10 @@ struct block_device *I_BDEV(struct inode *inode);
>  struct block_device *bdgrab(struct block_device *bdev);
>  void bdput(struct block_device *);
>  
> +int bio_add_hw_page(struct request_queue *q, struct bio *bio,
> +		struct page *page, unsigned int len, unsigned int offset,
> +		unsigned int max_sectors, bool *same_page);
> +
>  #ifdef CONFIG_BLOCK
>  void invalidate_bdev(struct block_device *bdev);
>  int truncate_bdev_range(struct block_device *bdev, fmode_t mode, loff_t lstart,
> 

Looks good.

Reviewed-by: Damien Le Moal <damien.lemoal at wdc.com>

-- 
Damien Le Moal
Western Digital Research