Re: [PATCH] t10-pi: reduce ref tag code duplication

[Christoph Hellwig <hch@infradead.org>]

On Fri, Apr 03, 2026 at 12:51:00PM -0600, Caleb Sander Mateos wrote:
> t10_pi_ref_tag() and ext_pi_ref_tag() are identical except for the final
> truncation of the ref tag to 32 or 48 bits. Factor out a helper
> full_pi_ref_tag() to return the untruncated ref tag and use it in
> t10_pi_ref_tag() and ext_pi_ref_tag().
> 
> Signed-off-by: Caleb Sander Mateos <csander@purestorage.com>
> ---
>  include/linux/t10-pi.h | 16 ++++++++--------
>  1 file changed, 8 insertions(+), 8 deletions(-)
> 
> diff --git a/include/linux/t10-pi.h b/include/linux/t10-pi.h
> index 2c59fe3efcd4..c6fe5db47c7a 100644
> --- a/include/linux/t10-pi.h
> +++ b/include/linux/t10-pi.h
> @@ -35,18 +35,23 @@ struct t10_pi_tuple {
>  };
>  
>  #define T10_PI_APP_ESCAPE cpu_to_be16(0xffff)
>  #define T10_PI_REF_ESCAPE cpu_to_be32(0xffffffff)
>  
> -static inline u32 t10_pi_ref_tag(struct request *rq)
> +static inline u64 full_pi_ref_tag(struct request *rq)
>  {
>  	unsigned int shift = ilog2(queue_logical_block_size(rq->q));
>  
>  	if (IS_ENABLED(CONFIG_BLK_DEV_INTEGRITY) &&
>  	    rq->q->limits.integrity.interval_exp)
>  		shift = rq->q->limits.integrity.interval_exp;
> -	return blk_rq_pos(rq) >> (shift - SECTOR_SHIFT) & 0xffffffff;
> +	return blk_rq_pos(rq) >> (shift - SECTOR_SHIFT);
> +}

This should probably move abouve the struct t10_pi_tuple definition
so that we keep clear blocks for classic vs extended PI.

> +
> +static inline u32 t10_pi_ref_tag(struct request *rq)
> +{
> +	return full_pi_ref_tag(rq) & 0xffffffff;

Use lower_32_bits here to make it more clear and mirror the ext version?

Otherwise looks good.