linux-kernel - [PATCH 3.13 131/172] mtd: nand: omap: fix ecclayout->oobfree->offset

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Date:	Tue,  4 Mar 2014 12:03:35 -0800
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org,
	Enric Balletbo i Serra <eballetbo@...il.com>,
	Stefan Roese <sr@...x.de>, Pekon Gupta <pekon@...com>,
	Brian Norris <computersforpeace@...il.com>
Subject: [PATCH 3.13 131/172] mtd: nand: omap: fix ecclayout->oobfree->offset

3.13-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Pekon Gupta <pekon@...com>

commit aa6092f9835893290e77c3e24649def49dac1583 upstream.

1) In current implementation, ecclayout->oobfree->offset is calculated with
 respect to ecclayout->eccpos[0] which is incorrect because ECC bytes may not
 be stored contiguously in OOB.
 So, this patch calculates ecclayout->oobfree->offset with respect to last
 ECC byte-position 'eccpos[ecclayout->eccbytes-1]'.

2) ECC layout of some ecc-schemes expects reserved-markers at specific eccpos[]
 which should not be over-written by any file-system metadata.
 So this patch aligns oobfree->offset taking into account of such markers.

Tested-by: Enric Balletbo i Serra <eballetbo@...il.com>
Tested-by: Stefan Roese <sr@...x.de>
Signed-off-by: Pekon Gupta <pekon@...com>
Signed-off-by: Brian Norris <computersforpeace@...il.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/mtd/nand/omap2.c |   25 +++++++++++++++----------
 1 file changed, 15 insertions(+), 10 deletions(-)

--- a/drivers/mtd/nand/omap2.c
+++ b/drivers/mtd/nand/omap2.c
@@ -1838,8 +1838,9 @@ static int omap_nand_probe(struct platfo
 			oob_index		= 1;
 		for (i = 0; i < ecclayout->eccbytes; i++, oob_index++)
 			ecclayout->eccpos[i]	= oob_index;
-		ecclayout->oobfree->offset	= ecclayout->eccpos[0] +
-							ecclayout->eccbytes;
+		/* no reserved-marker in ecclayout for this ecc-scheme */
+		ecclayout->oobfree->offset	=
+				ecclayout->eccpos[ecclayout->eccbytes - 1] + 1;
 		break;
 
 	case OMAP_ECC_BCH4_CODE_HW_DETECTION_SW:
@@ -1862,8 +1863,9 @@ static int omap_nand_probe(struct platfo
 			if (((i + 1) % nand_chip->ecc.bytes) == 0)
 				oob_index++;
 		}
-		ecclayout->oobfree->offset	= ecclayout->eccpos[0] +
-							ecclayout->eccbytes;
+		/* include reserved-marker in ecclayout->oobfree calculation */
+		ecclayout->oobfree->offset	= 1 +
+				ecclayout->eccpos[ecclayout->eccbytes - 1] + 1;
 		/* software bch library is used for locating errors */
 		nand_chip->ecc.priv		= nand_bch_init(mtd,
 							nand_chip->ecc.size,
@@ -1900,8 +1902,9 @@ static int omap_nand_probe(struct platfo
 		oob_index			= BADBLOCK_MARKER_LENGTH;
 		for (i = 0; i < ecclayout->eccbytes; i++, oob_index++)
 			ecclayout->eccpos[i]	= oob_index;
-		ecclayout->oobfree->offset	= ecclayout->eccpos[0] +
-							ecclayout->eccbytes;
+		/* reserved marker already included in ecclayout->eccbytes */
+		ecclayout->oobfree->offset	=
+				ecclayout->eccpos[ecclayout->eccbytes - 1] + 1;
 		/* This ECC scheme requires ELM H/W block */
 		if (is_elm_present(info, pdata->elm_of_node, BCH4_ECC) < 0) {
 			pr_err("nand: error: could not initialize ELM\n");
@@ -1935,8 +1938,9 @@ static int omap_nand_probe(struct platfo
 			if (((i + 1) % nand_chip->ecc.bytes) == 0)
 				oob_index++;
 		}
-		ecclayout->oobfree->offset	= ecclayout->eccpos[0] +
-							ecclayout->eccbytes;
+		/* include reserved-marker in ecclayout->oobfree calculation */
+		ecclayout->oobfree->offset	= 1 +
+				ecclayout->eccpos[ecclayout->eccbytes - 1] + 1;
 		/* software bch library is used for locating errors */
 		nand_chip->ecc.priv		= nand_bch_init(mtd,
 							nand_chip->ecc.size,
@@ -1980,8 +1984,9 @@ static int omap_nand_probe(struct platfo
 		oob_index			= BADBLOCK_MARKER_LENGTH;
 		for (i = 0; i < ecclayout->eccbytes; i++, oob_index++)
 			ecclayout->eccpos[i]	= oob_index;
-		ecclayout->oobfree->offset	= ecclayout->eccpos[0] +
-							ecclayout->eccbytes;
+		/* reserved marker already included in ecclayout->eccbytes */
+		ecclayout->oobfree->offset	=
+				ecclayout->eccpos[ecclayout->eccbytes - 1] + 1;
 		break;
 #else
 		pr_err("nand: error: CONFIG_MTD_NAND_OMAP_BCH not enabled\n");


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