linux-kernel - Re: [RESEND PATCH v5 2/5] mtd: ubi: use 'max_bad_blocks' to compute bad_peb

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Date:   Tue, 22 Nov 2016 10:42:15 -0800
From:   Brian Norris <computersforpeace@...il.com>
To:     Zach Brown <zach.brown@...com>
Cc:     dwmw2@...radead.org, boris.brezillon@...e-electrons.com,
        richard@....at, dedekind1@...il.com, linux-mtd@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Subject: Re: [RESEND PATCH v5 2/5] mtd: ubi: use 'max_bad_blocks' to compute
 bad_peb_limit if available

On Mon, Nov 21, 2016 at 01:51:36PM -0600, Zach Brown wrote:
> From: Jeff Westfahl <jeff.westfahl@...com>
> 
> Use the MTD function 'max_bad_blocks' to compute the UBI bad_peb_limit,
> if the function is implemented for an MTD and doesn't return an error.

I'm not exactly a UBI expert here, but it seems reasonable that we
should adjust the Kconfig documentation for MTD_UBI_BEB_LIMIT to further
emphasize that it's a default, if the value can't be determined by other
means.

> Signed-off-by: Jeff Westfahl <jeff.westfahl@...com>
> Signed-off-by: Zach Brown <zach.brown@...com>
> Acked-by: Boris Brezillon <boris.brezillon@...e-electron.com>
> ---
>  drivers/mtd/ubi/build.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/mtd/ubi/build.c b/drivers/mtd/ubi/build.c
> index 85d54f3..e9940a9 100644
> --- a/drivers/mtd/ubi/build.c
> +++ b/drivers/mtd/ubi/build.c
> @@ -584,6 +584,10 @@ static int get_bad_peb_limit(const struct ubi_device *ubi, int max_beb_per1024)
>  	int limit, device_pebs;
>  	uint64_t device_size;
>  
> +	limit = mtd_max_bad_blocks(ubi->mtd, 0, ubi->mtd->size);
> +	if (limit > 0)
> +		return limit;

Are you sure you want to even override the user-provided
max_beb_per1024 value taken from the mtd= line? I'd think if someone
went as far as to specify this in the kernel command line, they don't
expect it to get overridden. Just my two cents.

Brian

> +
>  	if (!max_beb_per1024)
>  		return 0;
>  
> -- 
> 2.7.4
>