On Mon 06-05-13 18:06:07, Maarten ter Huurne wrote:
> Subtracting the number of the first data block places the superblock
> backups one block too early, corrupting the file system. When the block
> size is larger than 1K, the first data block is 0, so the subtraction
> has no effect and no corruption occurs.
Looking where mke2fs places backup super blocks you are right. You can
add:
Reviewed-by: Jan Kara <jack@xxxxxxx>
Honza
>
> Signed-off-by: Maarten ter Huurne <maarten@xxxxxxxxxxxxxx>
> ---
> fs/ext4/resize.c | 4 +---
> 1 file changed, 1 insertion(+), 3 deletions(-)
>
> diff --git a/fs/ext4/resize.c b/fs/ext4/resize.c
> index c169477..116c80d 100644
> --- a/fs/ext4/resize.c
> +++ b/fs/ext4/resize.c
> @@ -1654,12 +1654,10 @@ errout:
> err = err2;
>
> if (!err) {
> - ext4_fsblk_t first_block;
> - first_block = ext4_group_first_block_no(sb, 0);
> if (test_opt(sb, DEBUG))
> printk(KERN_DEBUG "EXT4-fs: extended group to %llu "
> "blocks\n", ext4_blocks_count(es));
> - update_backups(sb, EXT4_SB(sb)->s_sbh->b_blocknr - first_block,
> + update_backups(sb, EXT4_SB(sb)->s_sbh->b_blocknr,
> (char *)es, sizeof(struct ext4_super_block), 0);
> }
> return err;
> --
> 1.7.10.4
>
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--
Jan Kara <jack@xxxxxxx>
SUSE Labs, CR
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