It think it should return -EROFS.

Also, change >= to >. I don't think this error message needs to know
that 1 bit is consumed by the header.

Rest looks good.

On 10/01/2010 01:53 PM, Srinivas Eeda wrote:
> This patch adds a safe check to ensure bg_free_bits_count doesn't exceed
> bg_bits in a group descriptor. This is to avoid on disk corruption that was
> seen recently.
>
> debugfs: group<52803072>
>         Group Chain: 179   Parent Inode: 11  Generation: 2959379682
>         CRC32: 00000000   ECC: 0000
>         ##   Block#            Total    Used     Free     Contig   Size
>         0    52803072          32256    4294965350   34202    18207    4032
>         ......
>
> Signed-off-by: Srinivas Eeda<[email protected]>
> ---
>   fs/ocfs2/suballoc.c |   16 ++++++++++++++++
>   1 files changed, 16 insertions(+), 0 deletions(-)
>
> diff --git a/fs/ocfs2/suballoc.c b/fs/ocfs2/suballoc.c
> index 849c2f0..d606a79 100644
> --- a/fs/ocfs2/suballoc.c
> +++ b/fs/ocfs2/suballoc.c
> @@ -1380,6 +1380,14 @@ static inline int ocfs2_block_group_set_bits(handle_t 
> *handle,
>       }
>
>       le16_add_cpu(&bg->bg_free_bits_count, -num_bits);
> +     if (le16_to_cpu(bg->bg_free_bits_count)>= le16_to_cpu(bg->bg_bits)) {
> +             ocfs2_error(alloc_inode->i_sb, "Group descriptor # %llu has bit"
> +                         " count %u but claims %u are freed. num_bits %d",
> +                         (unsigned long long)le64_to_cpu(bg->bg_blkno),
> +                         le16_to_cpu(bg->bg_bits),
> +                         le16_to_cpu(bg->bg_free_bits_count), num_bits);
> +             return -EIO;
> +     }
>       while(num_bits--)
>               ocfs2_set_bit(bit_off++, bitmap);
>
> @@ -2419,6 +2427,14 @@ static int ocfs2_block_group_clear_bits(handle_t 
> *handle,
>                               (unsigned long *) undo_bg->bg_bitmap);
>       }
>       le16_add_cpu(&bg->bg_free_bits_count, num_bits);
> +     if (le16_to_cpu(bg->bg_free_bits_count)>= le16_to_cpu(bg->bg_bits)) {
> +             ocfs2_error(alloc_inode->i_sb, "Group descriptor # %llu has bit"
> +                         " count %u but claims %u are freed. num_bits %d",
> +                         (unsigned long long)le64_to_cpu(bg->bg_blkno),
> +                         le16_to_cpu(bg->bg_bits),
> +                         le16_to_cpu(bg->bg_free_bits_count), num_bits);
> +             return -EIO;
> +     }
>
>       if (undo_fn)
>               jbd_unlock_bh_state(group_bh);
>    


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