linux-kernel - [ 081/147] JFFS2: dont fail on bitflips in OOB

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Date:	Sun, 14 Oct 2012 15:36:54 +0100
From:	Ben Hutchings <ben@...adent.org.uk>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:	akpm@...ux-foundation.org, alan@...rguk.ukuu.org.uk,
	Brian Norris <computersforpeace@...il.com>,
	Artem Bityutskiy <artem.bityutskiy@...ux.intel.com>,
	David Woodhouse <David.Woodhouse@...el.com>
Subject: [ 081/147] JFFS2: dont fail on bitflips in OOB

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

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

From: Brian Norris <computersforpeace@...il.com>

commit 74d83beaa229aac7d126ac1ed9414658ff1a89d2 upstream.

JFFS2 was designed without thought for OOB bitflips, it seems, but they
can occur and will be reported to JFFS2 via mtd_read_oob()[1]. We don't
want to fail on these transactions, since the data was corrected.

[1] Few drivers report bitflips for OOB-only transactions. With such
    drivers, this patch should have no effect.

Signed-off-by: Brian Norris <computersforpeace@...il.com>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@...ux.intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@...el.com>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 fs/jffs2/wbuf.c |    8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

--- a/fs/jffs2/wbuf.c
+++ b/fs/jffs2/wbuf.c
@@ -1032,11 +1032,11 @@ int jffs2_check_oob_empty(struct jffs2_s
 	ops.datbuf = NULL;
 
 	ret = c->mtd->read_oob(c->mtd, jeb->offset, &ops);
-	if (ret || ops.oobretlen != ops.ooblen) {
+	if ((ret && !mtd_is_bitflip(ret)) || ops.oobretlen != ops.ooblen) {
 		printk(KERN_ERR "cannot read OOB for EB at %08x, requested %zd"
 				" bytes, read %zd bytes, error %d\n",
 				jeb->offset, ops.ooblen, ops.oobretlen, ret);
-		if (!ret)
+		if (!ret || mtd_is_bitflip(ret))
 			ret = -EIO;
 		return ret;
 	}
@@ -1075,11 +1075,11 @@ int jffs2_check_nand_cleanmarker(struct
 	ops.datbuf = NULL;
 
 	ret = c->mtd->read_oob(c->mtd, jeb->offset, &ops);
-	if (ret || ops.oobretlen != ops.ooblen) {
+	if ((ret && !mtd_is_bitflip(ret)) || ops.oobretlen != ops.ooblen) {
 		printk(KERN_ERR "cannot read OOB for EB at %08x, requested %zd"
 				" bytes, read %zd bytes, error %d\n",
 				jeb->offset, ops.ooblen, ops.oobretlen, ret);
-		if (!ret)
+		if (!ret || mtd_is_bitflip(ret))
 			ret = -EIO;
 		return ret;
 	}


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