Re: [PATCH 4/5] nvme-pci: iod nents fits in s8

[Christoph Hellwig <hch@lst.de>]

On Thu, Jul 28, 2022 at 03:11:50PM -0700, Keith Busch wrote:
> From: Keith Busch <kbusch@kernel.org>
> 
> The maximum number of 'nents' allowed by the queue limit is 127, which
> fits in an 's8'.
> 
> Signed-off-by: Keith Busch <kbusch@kernel.org>
> ---
>  drivers/nvme/host/pci.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
> index 9e5bbf4e3e07..546de3c2000b 100644
> --- a/drivers/nvme/host/pci.c
> +++ b/drivers/nvme/host/pci.c
> @@ -229,7 +229,7 @@ struct nvme_iod {
>  	bool use_sgl;
>  	bool aborted;
>  	s8 npages;		/* In the PRP list. 0 means small pool in use */
> -	int nents;		/* Used in scatterlist */
> +	s8 nents;		/* Used in scatterlist */

Can we please have a BUILD_BUG_ON to protect us from an increased
max_segments?  As I can totally see us incrementing that at some point,
and the limit is somewhat close.