Re: [PATCH] mtd: improve calculating partition boundaries when checking for alignment

[Boris Brezillon <boris.brezillon@bootlin.com>]

On Tue, 20 Nov 2018 09:56:12 +0100
Rafał Miłecki <zajec5@gmail.com> wrote:

> From: Rafał Miłecki <rafal@milecki.pl>
> 
> When checking for alignment mtd should check absolute offsets. It's
> important for subpartitions as it doesn't make sense to check their
> relative addresses.
> 
> Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
> ---
>  drivers/mtd/mtdpart.c | 13 +++++++++++--
>  1 file changed, 11 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/mtd/mtdpart.c b/drivers/mtd/mtdpart.c
> index 2b6e53af47da..15197d923ec0 100644
> --- a/drivers/mtd/mtdpart.c
> +++ b/drivers/mtd/mtdpart.c
> @@ -61,6 +61,15 @@ static inline struct mtd_part *mtd_to_part(const struct mtd_info *mtd)
>  	return container_of(mtd, struct mtd_part, mtd);
>  }
>  
> +static uint64_t part_absolute_offset(struct mtd_info *mtd)

	  ^ u64

Looks good otherwise.

> +{
> +	struct mtd_part *part = mtd_to_part(mtd);
> +
> +	if (!mtd_is_partition(mtd))
> +		return 0;
> +
> +	return part_absolute_offset(part->parent) + part->offset;
> +}
>  
>  /*
>   * MTD methods which simply translate the effective address and pass through
> @@ -514,7 +523,7 @@ static struct mtd_part *allocate_partition(struct mtd_info *parent,
>  	if (!(slave->mtd.flags & MTD_NO_ERASE))
>  		wr_alignment = slave->mtd.erasesize;
>  
> -	tmp = slave->offset;
> +	tmp = part_absolute_offset(parent) + slave->offset;
>  	remainder = do_div(tmp, wr_alignment);
>  	if ((slave->mtd.flags & MTD_WRITEABLE) && remainder) {
>  		/* Doesn't start on a boundary of major erase size */
> @@ -525,7 +534,7 @@ static struct mtd_part *allocate_partition(struct mtd_info *parent,
>  			part->name);
>  	}
>  
> -	tmp = slave->mtd.size;
> +	tmp = part_absolute_offset(parent) + slave->mtd.size;
>  	remainder = do_div(tmp, wr_alignment);
>  	if ((slave->mtd.flags & MTD_WRITEABLE) && remainder) {
>  		slave->mtd.flags &= ~MTD_WRITEABLE;