On Nov 19, 2007 20:26 +0530, Aneesh Kumar K.V wrote:
> +static int ext4_valid_block_bitmap(struct super_block *sb,
> + struct ext4_group_desc *desc,
> + unsigned int block_group,
> + struct buffer_head *bh)
> +{
> + if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FLEX_BG)) {
> + /* with FLEX_BG, the inode/block bitmaps and itable
> + * blocks may not be in the group at all
> + * so the bitmap validation will be skipped for those groups
> + * or it has to also read the block group where the bitmaps
> + * are located to verify they are set.
> + */
> + return 1;
> + }
Rather than skipping the bitmap check entirely when FLEX_BG is enabled,
it is probably better to just validate whether each of the bitmap/itable
offsets are within the bitmap being read, like:
offset = ...
if (offset < EXT4_BLOCKS_PER_GROUP(sb) &&
ext4_test_bit(offset, bh->b_data))
/* bad block bitmap */
goto err_out;
Cheers, Andreas
--
Andreas Dilger
Sr. Software Engineer, Lustre Group
Sun Microsystems of Canada, Inc.
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