[ 3.5.yuz extended stable ] Patch "ext4: remove erroneous ext4_superblock_csum_set() in" has been added to staging queue

[Herton Ronaldo Krzesinski]

This is a note to let you know that I have just added a patch titled

    ext4: remove erroneous ext4_superblock_csum_set() in

to the linux-3.5.y-queue branch of the 3.5.yuz extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.5.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.5.yuz tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Herton

------

>From 81ea94ce7789ba7145d52018980f2d22a8623dfb Mon Sep 17 00:00:00 2001
From: Tao Ma <boyu.mt at taobao.com>
Date: Thu, 20 Sep 2012 11:35:38 -0400
Subject: [PATCH] ext4: remove erroneous ext4_superblock_csum_set() in
 update_backups()

commit bef53b01faeb791e27605cba1a71ba21364cb23e upstream.

The update_backups() function is used to backup all the metadata
blocks, so we should not take it for granted that 'data' is pointed to
a super block and use ext4_superblock_csum_set to calculate the
checksum there.  In case where the data is a group descriptor block,
it will corrupt the last group descriptor, and then e2fsck will
complain about it it.

As all the metadata checksums should already be OK when we do the
backup, remove the wrong ext4_superblock_csum_set and it should be
just fine.

Reported-by: "Theodore Ts'o" <tytso at mit.edu>
Signed-off-by: Tao Ma <boyu.mt at taobao.com>
Signed-off-by: "Theodore Ts'o" <tytso at mit.edu>
[ herton: adjust context ]
Signed-off-by: Herton Ronaldo Krzesinski <herton.krzesinski at canonical.com>
---
 fs/ext4/resize.c |    2 --
 1 file changed, 2 deletions(-)

diff --git a/fs/ext4/resize.c b/fs/ext4/resize.c
index b0bdd10..dc1affc 100644
--- a/fs/ext4/resize.c
+++ b/fs/ext4/resize.c
@@ -979,8 +979,6 @@ static void update_backups(struct super_block *sb,
 		goto exit_err;
 	}

-	ext4_superblock_csum_set(sb, (struct ext4_super_block *)data);
-
 	while ((group = ext4_list_backups(sb, &three, &five, &seven)) < last) {
 		struct buffer_head *bh;

--
1.7.9.5