Re: [PATCHv2] block: check for max_hw_sectors underflow

[John Garry <john.g.garry@oracle.com>]

On 24/05/2024 11:46, Hannes Reinecke wrote:
> The logical block size need to be smaller than the max_hw_sector
> setting, otherwise we can't even transfer a single LBA.
> 
> Signed-off-by: Hannes Reinecke <hare@kernel.org>

Regardless of comment, below:

Reviewed-by: John Garry <john.g.garry@oracle.com>

> ---
>   block/blk-settings.c | 8 ++++++--
>   1 file changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/block/blk-settings.c b/block/blk-settings.c
> index d2731843f2fc..030afb597183 100644
> --- a/block/blk-settings.c
> +++ b/block/blk-settings.c
> @@ -104,6 +104,7 @@ static int blk_validate_zoned_limits(struct queue_limits *lim)
>   static int blk_validate_limits(struct queue_limits *lim)
>   {
>   	unsigned int max_hw_sectors;
> +	unsigned int logical_block_sectors;
>   
>   	/*
>   	 * Unless otherwise specified, default to 512 byte logical blocks and a
> @@ -134,8 +135,11 @@ static int blk_validate_limits(struct queue_limits *lim)
>   		lim->max_hw_sectors = BLK_SAFE_MAX_SECTORS;
>   	if (WARN_ON_ONCE(lim->max_hw_sectors < PAGE_SECTORS))
>   		return -EINVAL;
> +	logical_block_sectors = lim->logical_block_size >> SECTOR_SHIFT;
> +	if (WARN_ON_ONCE(logical_block_sectors > lim->max_hw_sectors))
> +		return -EINVAL;
>   	lim->max_hw_sectors = round_down(lim->max_hw_sectors,

I don't think that we ever check if lim->logical_block_size is a 
power-of-2 - but that's a given, right?

> -			lim->logical_block_size >> SECTOR_SHIFT);
> +			logical_block_sectors);
>   
>   	/*
>   	 * The actual max_sectors value is a complex beast and also takes the
> @@ -153,7 +157,7 @@ static int blk_validate_limits(struct queue_limits *lim)
>   		lim->max_sectors = min(max_hw_sectors, BLK_DEF_MAX_SECTORS_CAP);
>   	}
>   	lim->max_sectors = round_down(lim->max_sectors,
> -			lim->logical_block_size >> SECTOR_SHIFT);
> +			logical_block_sectors);
>   
>   	/*
>   	 * Random default for the maximum number of segments.  Driver should not