linux-kernel - [PATCH 3.8 27/81] ext4: fix online resize with a non-standard blocks per group setting

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Message-Id: <1395767794-5012-28-git-send-email-kamal@canonical.com>
Date:	Tue, 25 Mar 2014 10:15:40 -0700
From:	Kamal Mostafa <kamal@...onical.com>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	kernel-team@...ts.ubuntu.com
Cc:	"Theodore Ts'o" <tytso@....edu>,
	Kamal Mostafa <kamal@...onical.com>
Subject: [PATCH 3.8 27/81] ext4: fix online resize with a non-standard blocks per group setting

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

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

From: Theodore Ts'o <tytso@....edu>

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@....edu>
Reported-by: Jon Bernard <jbernard@...ion.com>
Signed-off-by: Kamal Mostafa <kamal@...onical.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

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