linux-kernel - Re: [RESEND RESEND RESEND PATCH v2] mtd: nand_bbt: scan for next free bbt block if writing bbt fails

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Date:	Wed, 26 Aug 2015 17:07:31 -0700
From:	Brian Norris <computersforpeace@...il.com>
To:	Bean Huo 霍斌斌 (beanhuo) 
	<beanhuo@...ron.com>
Cc:	Xander Huff <xander.huff@...com>,
	"dwmw2@...radead.org" <dwmw2@...radead.org>,
	"linux-mtd@...ts.infradead.org" <linux-mtd@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"jeff.westfahl@...com" <jeff.westfahl@...com>,
	"jaeden.amero@...com" <jaeden.amero@...com>,
	"joshc@...com" <joshc@...com>, Ben Shelton <ben.shelton@...com>,
	Richard Weinberger <richard@....at>,
	Peter Pan 潘栋 (peterpandong) 
	<peterpandong@...ron.com>
Subject: Re: [RESEND RESEND RESEND PATCH v2] mtd: nand_bbt: scan for next
 free bbt block if writing bbt fails

On Wed, Aug 26, 2015 at 03:57:00PM +0000, Bean Huo 霍斌斌 (beanhuo) wrote:
> > On Tue, Aug 25, 2015 at 12:49:26PM -0500, Xander Huff wrote:

> > > diff --git a/drivers/mtd/nand/nand_bbt.c b/drivers/mtd/nand/nand_bbt.c
> > > index 63a1a36..09f9e62 100644
> > > --- a/drivers/mtd/nand/nand_bbt.c
> > > +++ b/drivers/mtd/nand/nand_bbt.c

> > > -787,13 +788,42 @@ static int write_bbt(struct mtd_info *mtd, uint8_t *buf,
> > >  		einfo.addr = to;
> > >  		einfo.len = 1 << this->bbt_erase_shift;
> > >  		res = nand_erase_nand(mtd, &einfo, 1);
> > > -		if (res < 0)
> > > +		if (res == -EIO && einfo.state == MTD_ERASE_FAILED
> > > +		    && einfo.priv == NAND_ERASE_BLOCK_ERASE_FAILED) {
> > 
> > Do you actually need that last condition? What's wrong with the first two?
> > 
> > > +			/* This block is bad. Mark it as such and see if
> > > +			 * there's another block available in the BBT area. */
> > > +			int block = page >>
> > > +				(this->bbt_erase_shift - this->page_shift);
> > > +			pr_info("nand_bbt: failed to erase block %d when writing
> > BBT\n",
> > > +				block);
> > > +			bbt_mark_entry(this, block, BBT_BLOCK_WORN);
> > > +
> > > +			res = this->block_markbad(mtd, block);
> > > +			if (res)
> > > +				pr_warn("nand_bbt: error %d while marking block %d
> > bad\n",
> > > +					res, block);
> > > +			goto next;
> > > +		} else if (res < 0)
> > >  			goto outerr;
> 
> 
> For my knowledge , we don't directly mark this block be a bad block,
> Just like ubi layer,this block also need to further testing and verify if
> It is real bad block.right?

That's a good point...we might want some kind of separate function for a
torture test. Might look at UBI's torture_peb() for inspiration.

> > >
> > >  		res = scan_write_bbt(mtd, to, len, buf,
> > >  				td->options & NAND_BBT_NO_OOB ? NULL :
> > >  				&buf[len]);
> > > -		if (res < 0)
> > > +		if (res == -EIO) {
> > > +			/* This block is bad. Mark it as such and see if
> > > +			 * there's another block available in the BBT area. */
> > > +			int block = page >>
> > > +				(this->bbt_erase_shift - this->page_shift);
> > > +			pr_info("nand_bbt: failed to erase block %d when writing
> > BBT\n",
> > > +				block);
> > > +			bbt_mark_entry(this, block, BBT_BLOCK_WORN);
> > > +
> > > +			res = this->block_markbad(mtd, block);
> > > +			if (res)
> > > +				pr_warn("nand_bbt: error %d while marking block %d
> > bad\n",
> > > +					res, block);
> > > +			goto next;
> > > +		} else if (res < 0)
> > >  			goto outerr;
> > >
> > >  		pr_info("Bad block table written to 0x%012llx, version 0x%02X\n",

Brian
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