linux-kernel - Re: [PATCH v1 2/2] jffs2: make cleanmarker support option

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Message-ID: <3951ac21-a0a4-47b5-be94-edb0140c69a5@salutedevices.com>
Date:   Mon, 23 Oct 2023 17:54:29 +0300
From:   Martin Kurbanov <mmkurbanov@...utedevices.com>
To:     Richard Weinberger <richard@....at>
CC:     David Woodhouse <dwmw2@...radead.org>,
        Christian Brauner <brauner@...nel.org>,
        Dave Chinner <dchinner@...hat.com>,
        Yu Zhe <yuzhe@...china.com>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        linux-mtd <linux-mtd@...ts.infradead.org>,
        <kernel@...rdevices.ru>
Subject: Re: [PATCH v1 2/2] jffs2: make cleanmarker support option

Hello Richard,

On 19.10.2023 11:12, Richard Weinberger wrote:
>> This patch support for disable cleanmarker option. This is useful on
>> some NAND devices which entire OOB area is protected by ECC. Problem
>> fires when JFFS2 driver writes cleanmarker to some page and later it
>> tries to write to this page - write will be done successfully, but after
>> that such page becomes unreadable due to invalid ECC codes. This occurs
>> because the second write necessitates an update to ECC, but it is
>> impossible to do it correctly without block erase.
> Hmm, I miss an explanation why this change is correct and safe.
> You explain why the OOB area can't be used, okay. But you need to
> add more details on why you change is safe in terms of filesystem
> consistency.
 
If you disable the cleanmarker, the found clean block (filled with 0xff)
will be erased again (see fs/jffs2/scan.c#L162).
In my opinion, it is better to perform the block erasure again than to
not work with such a nand flash at all.


> Beside of that, I don't think this should be kernel config option.
> Why not a mount option?

Agreed

-- 
Best Regards,
Martin Kurbanov