Re: [PATCHv2 4/4] null_blk: allow byte aligned memory offsets

[Christoph Hellwig <hch@lst.de>]

On Wed, Nov 05, 2025 at 05:54:47PM -0800, Keith Busch wrote:
> From: Keith Busch <kbusch@kernel.org>
> 
> Allowing byte aligned memory provides a nice testing ground for
> direct-io.
> 
> Signed-off-by: Keith Busch <kbusch@kernel.org>
> ---
>  drivers/block/null_blk/main.c  | 46 ++++++++++++++++++----------------
>  drivers/block/null_blk/zoned.c |  2 +-
>  2 files changed, 25 insertions(+), 23 deletions(-)
> 
> diff --git a/drivers/block/null_blk/main.c b/drivers/block/null_blk/main.c
> index 34346590d4eee..f1e67962ecaeb 100644
> --- a/drivers/block/null_blk/main.c
> +++ b/drivers/block/null_blk/main.c
> @@ -1130,25 +1130,27 @@ static int null_make_cache_space(struct nullb *nullb, unsigned long n)
>  }
>  
>  static blk_status_t copy_to_nullb(struct nullb *nullb, void *source,
> -				  sector_t sector, size_t n, bool is_fua)
> +				  loff_t pos, size_t n, bool is_fua)

Is it just me, or is n are way to non-descriptive argument name?  Can
we fix that if you touch it anyway?

>  {
>  	size_t temp, count = 0;
> -	unsigned int offset;
>  	struct nullb_page *t_page;
> +	sector_t sector;
>  
>  	while (count < n) {

And count here should be done of offset.  I really had a bit of a hard
time following the code due to the naming.

>  static blk_status_t null_transfer(struct nullb *nullb, struct page *page,
> -	unsigned int len, unsigned int off, bool is_write, sector_t sector,
> +	unsigned int len, unsigned int off, bool is_write, loff_t pos,
>  	bool is_fua)

.. and the indentation here could use fixing if we touch it anyway.

Otherwise looks good:

Reviewed-by: Christoph Hellwig <hch@lst.de>