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Date:   Fri, 28 Jun 2019 08:48:28 +0200 (CEST)
From:   Richard Weinberger <richard@nod.at>
To:     chengzhihao1@huawei.com
Cc:     david oberhollenzer <david.oberhollenzer@sigma-star.at>,
        david <david@sigma-star.at>,
        boris brezillon <boris.brezillon@free-electrons.com>,
        yi zhang <yi.zhang@huawei.com>,
        linux-mtd <linux-mtd@lists.infradead.org>,
        linux-kernel <linux-kernel@vger.kernel.org>
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Subject: Re: [PATCH RFC] mtd: ubi: Add fastmap sysfs attribute
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Zhihao Cheng,

----- Ursprüngliche Mail -----
> +	else if (attr == &dev_fastmap)
> +		ret = sprintf(buf, "%d\n", ubi->fm ? 1 : 0);
> 	else

I fear this is not correct. ubi->fm is an internal data structure
of UBI.
UBI sets it to NULL while it updates fastmap, and updates it later.
So userspace would see false negatives.

Thanks,
//richard