From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from smtp.nokia.com ([192.100.105.134] helo=mgw-mx09.nokia.com)
	by bombadil.infradead.org with esmtps (Exim 4.68 #1 (Red Hat Linux))
	id 1K8Atx-0005KB-9A
	for linux-mtd@lists.infradead.org; Mon, 16 Jun 2008 09:21:25 +0000
Message-ID: <4856309A.2070409@nokia.com>
Date: Mon, 16 Jun 2008 12:21:30 +0300
From: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
MIME-Version: 1.0
To: Zhao Forrest <forrest.zhao@gmail.com>
Subject: Re: A question about UBIFS
References: <ac8af0be0806102116l5918c48ax279d456b4de1d061@mail.gmail.com>	
	<48560B69.4080704@nokia.com>
	<ac8af0be0806160016p85be687n50110e2b9ce637df@mail.gmail.com>
In-Reply-To: <ac8af0be0806160016p85be687n50110e2b9ce637df@mail.gmail.com>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 8bit
Cc: linux-mtd@lists.infradead.org
Reply-To: Artem.Bityutskiy@nokia.com
List-Id: Linux MTD discussion mailing list <linux-mtd.lists.infradead.org>
List-Unsubscribe: <http://lists.infradead.org/mailman/listinfo/linux-mtd>,
	<mailto:linux-mtd-request@lists.infradead.org?subject=unsubscribe>
List-Archive: <http://lists.infradead.org/pipermail/linux-mtd>
List-Post: <mailto:linux-mtd@lists.infradead.org>
List-Help: <mailto:linux-mtd-request@lists.infradead.org?subject=help>
List-Subscribe: <http://lists.infradead.org/mailman/listinfo/linux-mtd>,
	<mailto:linux-mtd-request@lists.infradead.org?subject=subscribe>

Zhao Forrest wrote:
>> Zhao Forrest wrote:
>>> Hi Artem,
>>> I have a basic question about NAND flash page update in UBIFS/UBI,
>>> take the following as an example:
>>> 1 a NAND flash with page size of 4KB, erase block size of 256KB, so
>>> there're 64 pages within an erase block
>>> 2 page 0 - page 10 has invalid data content, page 11 - page 63 has
>>> valid data content from FS's point of view
>>> 3 UBIFS attempts to update(or rewrite) page 11
>>> My question is how page 11 is updated by UBIFS/UBI?
>>> I only read the design docs of UBI and guess that for this particular
>>> case a new physical eraseblock is got by UBI, then new content of page
>>> 11 is written to page 11 of new physical eraseblock, page 12 - page 63
>>> in original physical eraseblock are copied to new physical eraseblock,
>>> lastly the mapping between logical eraseblock and physical eraseblock
>>> is updated. Am I right?
>> Right. All updates are out-of-place.
>>
> So when only page 11 is rewritten, are pages 12-63 rewritten at the same time?
> Or page 11 is updated by wandering tree mechanism, and pages 12-63 are
> untouched?

The latter (12-63 are untouched).

-- 
Best Regards,
Artem Bityutskiy (Артём Битюцкий)