[PATCH v1 1/2] fs: fat: add macro to convert u8[2] to u16

[Alexander Dahl]

Hello Christian,

Am Wed, Nov 08, 2023 at 01:12:38PM +0100 schrieb christian.taedcke-oss at weidmueller.com:
> From: Christian Taedcke <christian.taedcke at weidmueller.com>
> 
> This reduces code duplications.
> 
> Signed-off-by: Christian Taedcke <christian.taedcke at weidmueller.com>
> ---
> 
>  fs/fat/fat.c | 9 +++++----
>  1 file changed, 5 insertions(+), 4 deletions(-)
> 
> diff --git a/fs/fat/fat.c b/fs/fat/fat.c
> index 8ff1fd0ec8..8a0f4e4e6c 100644
> --- a/fs/fat/fat.c
> +++ b/fs/fat/fat.c
> @@ -25,6 +25,8 @@
>  #include <linux/compiler.h>
>  #include <linux/ctype.h>
>  
> +#define FATU8ARRAY2CPU16(x) (((x)[1] << 8) + (x)[0])

This does the same as the generic `get_unaligned_le16()` … why not use
that?

Greets
Alex

> +
>  /*
>   * Convert a string to lowercase.  Converts at most 'len' characters,
>   * 'len' may be larger than the length of 'str' if 'str' is NULL
> @@ -571,7 +573,7 @@ static int get_fs_info(fsdata *mydata)
>  		mydata->total_sect = bs.total_sect;
>  	} else {
>  		mydata->fatlength = bs.fat_length;
> -		mydata->total_sect = (bs.sectors[1] << 8) + bs.sectors[0];
> +		mydata->total_sect = FATU8ARRAY2CPU16(bs.sectors);
>  		if (!mydata->total_sect)
>  			mydata->total_sect = bs.total_sect;
>  	}
> @@ -583,7 +585,7 @@ static int get_fs_info(fsdata *mydata)
>  
>  	mydata->rootdir_sect = mydata->fat_sect + mydata->fatlength * bs.fats;
>  
> -	mydata->sect_size = (bs.sector_size[1] << 8) + bs.sector_size[0];
> +	mydata->sect_size = FATU8ARRAY2CPU16(bs.sector_size);
>  	mydata->clust_size = bs.cluster_size;
>  	if (mydata->sect_size != cur_part_info.blksz) {
>  		log_err("FAT sector size mismatch (fs=%u, dev=%lu)\n",
> @@ -607,8 +609,7 @@ static int get_fs_info(fsdata *mydata)
>  					(mydata->clust_size * 2);
>  		mydata->root_cluster = bs.root_cluster;
>  	} else {
> -		mydata->rootdir_size = ((bs.dir_entries[1]  * (int)256 +
> -					 bs.dir_entries[0]) *
> +		mydata->rootdir_size = (FATU8ARRAY2CPU16(bs.dir_entries) *
>  					 sizeof(dir_entry)) /
>  					 mydata->sect_size;
>  		mydata->data_begin = mydata->rootdir_sect +
> -- 
> 2.34.1
>