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Subject[PATCH 3.16.y-ckt 030/126] [PATCH] fix calculation of meta_bg descriptor backups
3.16.7-ckt21 -stable review patch.  If anyone has any objections, please let me know.


From: Andy Leiserson <>

commit 904dad4742d211b7a8910e92695c0fa957483836 upstream.

"group" is the group where the backup will be placed, and is
initialized to zero in the declaration. This meant that backups for
meta_bg descriptors were erroneously written to the backup block group
descriptors in groups 1 and (desc_per_block-1).

Reproduction information:
mke2fs -Fq -t ext4 -b 1024 -O ^resize_inode /tmp/foo.img 16G
truncate -s 24G /tmp/foo.img
losetup /dev/loop0 /tmp/foo.img
mount /dev/loop0 /mnt
resize2fs /dev/loop0
umount /dev/loop0
dd if=/dev/zero of=/dev/loop0 bs=1024 count=2
e2fsck -fy /dev/loop0
losetup -d /dev/loop0

Signed-off-by: Andy Leiserson <>
Signed-off-by: Theodore Ts'o <>
Signed-off-by: Luis Henriques <>
fs/ext4/resize.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/ext4/resize.c b/fs/ext4/resize.c
index ca4588388fc3..dd4f37e2f18f 100644
--- a/fs/ext4/resize.c
+++ b/fs/ext4/resize.c
@@ -1040,7 +1040,7 @@ exit_free:
* do not copy the full number of backups at this time. The resize
* which changed s_groups_count will backup again.
-static void update_backups(struct super_block *sb, int blk_off, char *data,
+static void update_backups(struct super_block *sb, sector_t blk_off, char *data,
int size, int meta_bg)
struct ext4_sb_info *sbi = EXT4_SB(sb);
@@ -1065,7 +1065,7 @@ static void update_backups(struct super_block *sb, int blk_off, char *data,
group = ext4_list_backups(sb, &three, &five, &seven);
last = sbi->s_groups_count;
} else {
- group = ext4_meta_bg_first_group(sb, group) + 1;
+ group = ext4_get_group_number(sb, blk_off) + 1;
last = (ext4_group_t)(group + EXT4_DESC_PER_BLOCK(sb) - 2);

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