[RESEND v5] mtd: nand_bbt: scan for next free bbt block if writing bbt fails

[RESEND v5] mtd: nand_bbt: scan for next free bbt block if writing bbt fails

[Kyle Roeschley]

If erasing or writing the BBT fails, we should mark the current BBT
block as bad and use the BBT descriptor to scan for the next available
unused block in the BBT. We should only return a failure if there isn't
any space left.

Based on original code implemented by Jeff Westfahl
<jeff.westfahl@ni.com>.

Signed-off-by: Kyle Roeschley <kyle.roeschley@ni.com>
Suggested-by: Jeff Westfahl <jeff.westfahl@ni.com>
---
v5: De-duplicate bad block handling

v4: Don't ignore write protection while marking bad BBT blocks
    Correctly call block_markbad
    Minor cleanups

v3: Don't overload mtd->priv
    Keep nand_erase_nand from erroring on protected BBT blocks

v2: Mark OOB area in each block as well as BBT
    Avoid marking read-only, bad address, or known bad blocks as bad

 drivers/mtd/nand/nand_bbt.c | 40 ++++++++++++++++++++++++++++++++++------
 1 file changed, 34 insertions(+), 6 deletions(-)

diff --git a/drivers/mtd/nand/nand_bbt.c b/drivers/mtd/nand/nand_bbt.c
index 2fbb523..c9255f8 100644
--- a/drivers/mtd/nand/nand_bbt.c
+++ b/drivers/mtd/nand/nand_bbt.c
@@ -620,7 +620,7 @@ static int write_bbt(struct mtd_info *mtd, uint8_t *buf,
 {
 	struct nand_chip *this = mtd_to_nand(mtd);
 	struct erase_info einfo;
-	int i, res, chip = 0;
+	int i, res, chip = 0, found_bad_block = 0;
 	int bits, startblock, dir, page, offs, numblocks, sft, sftmsk;
 	int nrchips, pageoffs, ooboffs;
 	uint8_t msk[4];
@@ -663,6 +663,27 @@ static int write_bbt(struct mtd_info *mtd, uint8_t *buf,
 			goto write;
 		}
 
+next:
+		if (found_bad_block) {
+			/*
+			 * We found a bad block on the last loop iteration.
+			 * 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, to);
+			if (res)
+				pr_warn("nand_bbt: error %d while marking block %d bad\n",
+					res, block);
+			td->pages[chip] = -1;
+			found_bad_block = 0;
+		}
+
 		/*
 		 * Automatic placement of the bad block table. Search direction
 		 * top -> down?
@@ -787,14 +808,21 @@ 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) {
+			found_bad_block = 1;
+			goto next;
+		} else if (res) {
 			goto outerr;
+		}
 
-		res = scan_write_bbt(mtd, to, len, buf,
-				td->options & NAND_BBT_NO_OOB ? NULL :
-				&buf[len]);
-		if (res < 0)
+		res = scan_write_bbt(mtd, to, len, buf, td->options &
+				     NAND_BBT_NO_OOB ? NULL : &buf[len]);
+		if (res == -EIO) {
+			found_bad_block = 1;
+			goto next;
+		} else if (res) {
 			goto outerr;
+		}
 
 		pr_info("Bad block table written to 0x%012llx, version 0x%02X\n",
 			 (unsigned long long)to, td->version[chip]);
-- 
2.8.1

Re: [RESEND v5] mtd: nand_bbt: scan for next free bbt block if writing bbt fails

[Boris Brezillon]

Hi Kyle,

On Tue, 2 Aug 2016 15:01:50 -0500
Kyle Roeschley <kyle.roeschley@ni.com> wrote:

> If erasing or writing the BBT fails, we should mark the current BBT
> block as bad and use the BBT descriptor to scan for the next available
> unused block in the BBT. We should only return a failure if there isn't
> any space left.
> 
> Based on original code implemented by Jeff Westfahl
> <jeff.westfahl@ni.com>.
> 
> Signed-off-by: Kyle Roeschley <kyle.roeschley@ni.com>
> Suggested-by: Jeff Westfahl <jeff.westfahl@ni.com>
> ---
> v5: De-duplicate bad block handling
> 
> v4: Don't ignore write protection while marking bad BBT blocks
>     Correctly call block_markbad
>     Minor cleanups
> 
> v3: Don't overload mtd->priv
>     Keep nand_erase_nand from erroring on protected BBT blocks
> 
> v2: Mark OOB area in each block as well as BBT
>     Avoid marking read-only, bad address, or known bad blocks as bad
> 
>  drivers/mtd/nand/nand_bbt.c | 40 ++++++++++++++++++++++++++++++++++------
>  1 file changed, 34 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/mtd/nand/nand_bbt.c b/drivers/mtd/nand/nand_bbt.c
> index 2fbb523..c9255f8 100644
> --- a/drivers/mtd/nand/nand_bbt.c
> +++ b/drivers/mtd/nand/nand_bbt.c
> @@ -620,7 +620,7 @@ static int write_bbt(struct mtd_info *mtd, uint8_t *buf,
>  {
>  	struct nand_chip *this = mtd_to_nand(mtd);
>  	struct erase_info einfo;
> -	int i, res, chip = 0;
> +	int i, res, chip = 0, found_bad_block = 0;
>  	int bits, startblock, dir, page, offs, numblocks, sft, sftmsk;
>  	int nrchips, pageoffs, ooboffs;
>  	uint8_t msk[4];
> @@ -663,6 +663,27 @@ static int write_bbt(struct mtd_info *mtd, uint8_t *buf,
>  			goto write;
>  		}
>  
> +next:
> +		if (found_bad_block) {
> +			/*
> +			 * We found a bad block on the last loop iteration.
> +			 * 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, to);
> +			if (res)
> +				pr_warn("nand_bbt: error %d while marking block %d bad\n",
> +					res, block);
> +			td->pages[chip] = -1;
> +			found_bad_block = 0;
> +		}
> +

Yet another label in this already non-trivial function. Can we do
something like that [1][2] instead?

Regards,

Boris

>  		/*
>  		 * Automatic placement of the bad block table. Search direction
>  		 * top -> down?
> @@ -787,14 +808,21 @@ 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) {
> +			found_bad_block = 1;
> +			goto next;
> +		} else if (res) {
>  			goto outerr;
> +		}
>  
> -		res = scan_write_bbt(mtd, to, len, buf,
> -				td->options & NAND_BBT_NO_OOB ? NULL :
> -				&buf[len]);
> -		if (res < 0)
> +		res = scan_write_bbt(mtd, to, len, buf, td->options &
> +				     NAND_BBT_NO_OOB ? NULL : &buf[len]);
> +		if (res == -EIO) {
> +			found_bad_block = 1;
> +			goto next;
> +		} else if (res) {
>  			goto outerr;
> +		}
>  
>  		pr_info("Bad block table written to 0x%012llx, version 0x%02X\n",
>  			 (unsigned long long)to, td->version[chip]);

[1]http://code.bulix.org/3xbnwr-104986
[2]http://code.bulix.org/e16nvo-104988