[U-Boot] [PATCH] FIX: fat: Provide correct return code from disk_{read|write} to upper layers

[Lukasz Majewski]

Hi,

> It is very common that FAT code is using following pattern:
> if (disk_{read|write}() < 0)
>         return -1;
> 
> Up till now the above code was dead, since disk_{read|write) could
> only return value >= 0.
> As a result some errors from medium layer (i.e. eMMC/SD) were not
> caught.
> 
> The above behavior was caused by block_{read|write|erase} declared at
> struct block_dev_desc (@part.h). It returns unsigned long, where 0
> indicates error and > 0 indicates that medium operation was correct.
> 
> This patch as error regards 0 returned from block_{read|write|erase}
> when nr_blocks is grater than zero. Read/Write operation with
> nr_blocks=0 should return 0 and hence is not considered as an error.
> 
> Signed-off-by: Lukasz Majewski <l.majewski at samsung.com>

Are there any more questions regarding this patch? I'd be more than
happy if it would be added to v2015.10 :-).

> 
> Test HW: Odroid XU3 - Exynos 5433
> ---
>  fs/fat/fat.c       | 11 +++++++++--
>  fs/fat/fat_write.c | 11 +++++++++--
>  2 files changed, 18 insertions(+), 4 deletions(-)
> 
> diff --git a/fs/fat/fat.c b/fs/fat/fat.c
> index bccc3e3..d743014 100644
> --- a/fs/fat/fat.c
> +++ b/fs/fat/fat.c
> @@ -45,11 +45,18 @@ static disk_partition_t cur_part_info;
>  
>  static int disk_read(__u32 block, __u32 nr_blocks, void *buf)
>  {
> +	ulong ret;
> +
>  	if (!cur_dev || !cur_dev->block_read)
>  		return -1;
>  
> -	return cur_dev->block_read(cur_dev->dev,
> -			cur_part_info.start + block, nr_blocks, buf);
> +	ret = cur_dev->block_read(cur_dev->dev,
> +				  cur_part_info.start + block,
> nr_blocks, buf); +
> +	if (nr_blocks && ret == 0)
> +		return -1;
> +
> +	return ret;
>  }
>  
>  int fat_set_blk_dev(block_dev_desc_t *dev_desc, disk_partition_t
> *info) diff --git a/fs/fat/fat_write.c b/fs/fat/fat_write.c
> index 98b88ad..adb6940 100644
> --- a/fs/fat/fat_write.c
> +++ b/fs/fat/fat_write.c
> @@ -30,6 +30,8 @@ static void uppercase(char *str, int len)
>  static int total_sector;
>  static int disk_write(__u32 block, __u32 nr_blocks, void *buf)
>  {
> +	ulong ret;
> +
>  	if (!cur_dev || !cur_dev->block_write)
>  		return -1;
>  
> @@ -39,8 +41,13 @@ static int disk_write(__u32 block, __u32
> nr_blocks, void *buf) return -1;
>  	}
>  
> -	return cur_dev->block_write(cur_dev->dev,
> -			cur_part_info.start + block,
> nr_blocks,	buf);
> +	ret = cur_dev->block_write(cur_dev->dev,
> +				   cur_part_info.start + block,
> +				   nr_blocks, buf);
> +	if (nr_blocks && ret == 0)
> +		return -1;
> +
> +	return ret;
>  }
>  
>  /*



-- 
Best regards,

Lukasz Majewski

Samsung R&D Institute Poland (SRPOL) | Linux Platform Group