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Date:   Fri, 16 Jul 2021 01:02:24 +0200
From:   Miquel Raynal <miquel.raynal@bootlin.com>
To:     Miaohe Lin <linmiaohe@huawei.com>
Cc:     <richard@nod.at>, <vigneshr@ti.com>, <David.Woodhouse@intel.com>,
        <Artem.Bityutskiy@nokia.com>, <ext-adrian.hunter@nokia.com>,
        <linux-kernel@vger.kernel.org>, <linux-mtd@lists.infradead.org>,
        <linfeilong@huawei.com>
Subject: Re: [PATCH] mtd: fix size in mtd_info_user to support 64-bit
Message-ID: <20210716010224.44582046@xps13>
In-Reply-To: <20210708131359.21591-1-linmiaohe@huawei.com>
References: <20210708131359.21591-1-linmiaohe@huawei.com>
Organization: Bootlin
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Hi Miaohe,

Miaohe Lin <linmiaohe@huawei.com> wrote on Thu, 8 Jul 2021 21:13:59
+0800:

> From: Feilong Lin <linfeilong@huawei.com>
> 
> The size in struct mtd_info_user is 32-bit, which will cause errors
> when obtaining the size of large-capacity MTD devices, such as TLC
> NAND FLASH-2048Gb.

Besides the fact that such devices are far from being supported by the
Linux kernel, this change would basically break userspace, it cannot
enter as-is...

> Fixes: 69423d99fc18 ("[MTD] update internal API to support 64-bit device size")
> Signed-off-by: Feilong Lin <linfeilong@huawei.com>
> ---
>  include/uapi/mtd/mtd-abi.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/include/uapi/mtd/mtd-abi.h b/include/uapi/mtd/mtd-abi.h
> index b869990c2db2..efe0b53b10c1 100644
> --- a/include/uapi/mtd/mtd-abi.h
> +++ b/include/uapi/mtd/mtd-abi.h
> @@ -128,7 +128,7 @@ struct mtd_write_req {
>  struct mtd_info_user {
>  	__u8 type;
>  	__u32 flags;
> -	__u32 size;	/* Total size of the MTD */
> +	__u64 size;	/* Total size of the MTD */
>  	__u32 erasesize;
>  	__u32 writesize;
>  	__u32 oobsize;	/* Amount of OOB data per block (e.g. 16) */

Thanks,
Miquèl