linux-kernel - Re: [PATCH 19/20] pstore: fs superblock limits

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Message-ID: <201907292129.AC796230@keescook>
Date:   Mon, 29 Jul 2019 21:31:44 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Deepa Dinamani <deepa.kernel@...il.com>
Cc:     viro@...iv.linux.org.uk, linux-kernel@...r.kernel.org,
        linux-fsdevel@...r.kernel.org, arnd@...db.de,
        y2038@...ts.linaro.org, anton@...msg.org, ccross@...roid.com,
        tony.luck@...el.com
Subject: Re: [PATCH 19/20] pstore: fs superblock limits

On Mon, Jul 29, 2019 at 06:49:23PM -0700, Deepa Dinamani wrote:
> Also update the gran since pstore has microsecond granularity.

So, I'm fine with this, but technically the granularity depends on the
backend storage... many have no actual time keeping, though. My point is,
pstore's timestamps are really mostly a lie, but the most common backend
(ramoops) is seconds-granularity.

So, I'm fine with this, but it's a lie but it's a lie that doesn't
matter, so ...

Acked-by: Kees Cook <keescook@...omium.org>

I'm open to suggestions to improve it...

-Kees

> 
> Signed-off-by: Deepa Dinamani <deepa.kernel@...il.com>
> Cc: anton@...msg.org
> Cc: ccross@...roid.com
> Cc: keescook@...omium.org
> Cc: tony.luck@...el.com
> ---
>  fs/pstore/inode.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/pstore/inode.c b/fs/pstore/inode.c
> index 89a80b568a17..ee752f9fda57 100644
> --- a/fs/pstore/inode.c
> +++ b/fs/pstore/inode.c
> @@ -388,7 +388,9 @@ static int pstore_fill_super(struct super_block *sb, void *data, int silent)
>  	sb->s_blocksize_bits	= PAGE_SHIFT;
>  	sb->s_magic		= PSTOREFS_MAGIC;
>  	sb->s_op		= &pstore_ops;
> -	sb->s_time_gran		= 1;
> +	sb->s_time_gran         = NSEC_PER_USEC;
> +	sb->s_time_min		= S64_MIN;
> +	sb->s_time_max		= S64_MAX;
>  
>  	parse_options(data);
>  
> -- 
> 2.17.1
> 

-- 
Kees Cook