[3.8.y.z extended stable] Patch "ext4: fix online resize with a non-standard blocks per group setting" has been added to staging queue

[Kamal Mostafa]

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

    ext4: fix online resize with a non-standard blocks per group setting

to the linux-3.8.y-queue branch of the 3.8.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.8.y-queue

This patch is scheduled to be released in version 3.8.13.20.

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

For more information about the 3.8.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From e983b519c97f6875ff8295697dd67e6f4b84db92 Mon Sep 17 00:00:00 2001
From: Theodore Ts'o <tytso at mit.edu>
Date: Sat, 15 Feb 2014 22:42:25 -0500
Subject: ext4: fix online resize with a non-standard blocks per group setting

commit 3d2660d0c9c2f296837078c189b68a47f6b2e3b5 upstream.

The set_flexbg_block_bitmap() function assumed that the number of
blocks in a blockgroup was sb->blocksize * 8, which is normally true,
but not always!  Use EXT4_BLOCKS_PER_GROUP(sb) instead, to fix block
bitmap corruption after:

mke2fs -t ext4 -g 3072 -i 4096 /dev/vdd 1G
mount -t ext4 /dev/vdd /vdd
resize2fs /dev/vdd 8G

Signed-off-by: "Theodore Ts'o" <tytso at mit.edu>
Reported-by: Jon Bernard <jbernard at tuxion.com>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 fs/ext4/resize.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/ext4/resize.c b/fs/ext4/resize.c
index d2c12df..d7f6b63 100644
--- a/fs/ext4/resize.c
+++ b/fs/ext4/resize.c
@@ -404,7 +404,7 @@ static int set_flexbg_block_bitmap(struct super_block *sb, handle_t *handle,
 		start = ext4_group_first_block_no(sb, group);
 		group -= flex_gd->groups[0].group;

-		count2 = sb->s_blocksize * 8 - (block - start);
+		count2 = EXT4_BLOCKS_PER_GROUP(sb) - (block - start);
 		if (count2 > count)
 			count2 = count;

--
1.8.3.2