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From: Richard Weinberger <richard@nod.at>
To: "Bean Huo (beanhuo)" <beanhuo@micron.com>
Cc: "linux-mtd@lists.infradead.org" <linux-mtd@lists.infradead.org>,
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 "tglx@linutronix.de" <tglx@linutronix.de>,
 Boris Brezillon <boris.brezillon@bootlin.com>
Subject: Re: [EXT] Re: [PATCH V1] mtd: core: Micron SLC NAND filling block
Date: Wed, 19 Dec 2018 19:28:28 +0100
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Bean,

Am Mittwoch, 19. Dezember 2018, 19:11:25 CET schrieb Bean Huo (beanhuo):
> >If you overwrite (sub)pages 0 and 1, UBI EC and VID headers are gone.
> >In case of a power-cut before the erase operation, UBI will detect the
> >corrupted EC and VID headers and re-erase the block.
> 
> This is actually what I want. Means always overwrite EC and VID headers, in order to 
> let UBI to re-erase this block just because of this block contains my filling data (resulting from one power-cut after filling pages).
> Otherwise, for the next boot, during attach stage, UBIFS will consider this block to be a corrupted block.
> 
> let me take one example, eg, the last programmed page is page8, and after the filling pages, 
> before mtd->_erase, power-cut hits, so in this block, there will be below data layout, 
> 
> Page0 : EC header
> Page1: VID header
> Page2: not empty, valid data 
> Page3: not empty, valid data
> Page4: not empty, valid data
> Page5: not empty, valid data
> Page6: not empty, valid data
> Page7: not empty, valid data
> Page8: not empty, valid data
> 
> Page9: filled with padding data by the patch
> Page10: empty, keep all 0xff
> Page11: filled with padding data by the patch
> Page12: empty, keep all 0xff
> Page13: filled with padding data by the patch
> 
> As for the older UBIFS (eg, v4.2), there will result in attach failure, but for the latest
> UBIFS, if I don't overwrite EC and VID header, will this condition happen?

Sorry I didn't make myself clear. It is perfectly fine to kill both EC and VID headers.
This is actually what we want.

Thanks,
//richard