linux-ext4 - Re: [PATCH] ext2: Make sb magic number endianness conversion consistent

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Date:	Thu, 17 Oct 2013 19:50:59 +0200 (CEST)
From:	Lukáš Czerner <lczerner@...hat.com>
To:	Carlos Maiolino <cmaiolino@...hat.com>
cc:	linux-ext4@...r.kernel.org
Subject: Re: [PATCH] ext2: Make sb magic number endianness conversion
 consistent

On Thu, 17 Oct 2013, Carlos Maiolino wrote:

> Date: Thu, 17 Oct 2013 14:24:58 -0300
> From: Carlos Maiolino <cmaiolino@...hat.com>
> To: linux-ext4@...r.kernel.org
> Subject: [PATCH] ext2: Make sb magic number endianness conversion consistent
> 
> All ext2_super_block fields are converted from le16 to cpu when checked or
> loaded into memory. Magic number check is the only field where we convert the
> magic number to le16. So, make the conversion pattern consistent with the
> remaining code

This not exactly true since this kind of comparison when a constant
is converted rather the variable is present on several places in
ext2, ext3 and ext4 (ext3 and ext4 have the same check you're fixing
here as well). I personally do not see the problem with this,
so honestly I do not see a reason to fix this.

Thanks!
-Lukas

> 
> Signed-off-by: Carlos Maiolino <cmaiolino@...hat.com>
> ---
>  fs/ext2/super.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/ext2/super.c b/fs/ext2/super.c
> index 2885349..808f99f 100644
> --- a/fs/ext2/super.c
> +++ b/fs/ext2/super.c
> @@ -927,7 +927,7 @@ static int ext2_fill_super(struct super_block *sb, void *data, int silent)
>  		}
>  		es = (struct ext2_super_block *) (((char *)bh->b_data) + offset);
>  		sbi->s_es = es;
> -		if (es->s_magic != cpu_to_le16(EXT2_SUPER_MAGIC)) {
> +		if (le16_to_cpu(es->s_magic) != EXT2_SUPER_MAGIC) {
>  			ext2_msg(sb, KERN_ERR, "error: magic mismatch");
>  			goto failed_mount;
>  		}
> 
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