Re: [PATCH 11/17] xfs: simplify xfs_buf_submit_bio

["Darrick J. Wong" <djwong@kernel.org>]

On Tue, Apr 22, 2025 at 04:26:12PM +0200, Christoph Hellwig wrote:
> Convert the __bio_add_page(..., virt_to_page(), ...) pattern to the
> bio_add_virt_nofail helper implementing it and use bio_add_vmalloc
> to insulate xfs from the details of adding vmalloc memory to a bio.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>

That reads much more cleanly now :)
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>

--D

> ---
>  fs/xfs/xfs_buf.c | 27 ++++++++-------------------
>  1 file changed, 8 insertions(+), 19 deletions(-)
> 
> diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
> index 1a2b3f06fa71..042a738b7fda 100644
> --- a/fs/xfs/xfs_buf.c
> +++ b/fs/xfs/xfs_buf.c
> @@ -1339,37 +1339,26 @@ xfs_buf_submit_bio(
>  
>  	if (is_vmalloc_addr(bp->b_addr)) {
>  		unsigned int	size = BBTOB(bp->b_length);
> -		unsigned int	alloc_size = roundup(size, PAGE_SIZE);
>  		void		*data = bp->b_addr;
> +		unsigned int	added;
>  
> -		bio = bio_alloc(bp->b_target->bt_bdev, alloc_size >> PAGE_SHIFT,
> -				xfs_buf_bio_op(bp), GFP_NOIO);
> +		bio = bio_alloc(bp->b_target->bt_bdev,
> +				howmany(size, PAGE_SIZE), xfs_buf_bio_op(bp),
> +				GFP_NOIO);
>  
>  		do {
> -			unsigned int	len = min(size, PAGE_SIZE);
> -
> -			ASSERT(offset_in_page(data) == 0);
> -			__bio_add_page(bio, vmalloc_to_page(data), len, 0);
> -			data += len;
> -			size -= len;
> +			added = bio_add_vmalloc(bio, data, size);
> +			data += added;
> +			size -= added;
>  		} while (size);
> -
> -		flush_kernel_vmap_range(bp->b_addr, alloc_size);
>  	} else {
>  		/*
>  		 * Single folio or slab allocation.  Must be contiguous and thus
>  		 * only a single bvec is needed.
> -		 *
> -		 * This uses the page based bio add helper for now as that is
> -		 * the lowest common denominator between folios and slab
> -		 * allocations.  To be replaced with a better block layer
> -		 * helper soon (hopefully).
>  		 */
>  		bio = bio_alloc(bp->b_target->bt_bdev, 1, xfs_buf_bio_op(bp),
>  				GFP_NOIO);
> -		__bio_add_page(bio, virt_to_page(bp->b_addr),
> -				BBTOB(bp->b_length),
> -				offset_in_page(bp->b_addr));
> +		bio_add_virt_nofail(bio, bp->b_addr, BBTOB(bp->b_length));
>  	}
>  
>  	bio->bi_private = bp;
> -- 
> 2.47.2
> 
>