Re: [PATCH] ext3: Properly report backup blocks present in a group

From: Alexey Dobriyan
Date: Fri Jan 20 2006 - 14:42:23 EST


On Fri, Jan 20, 2006 at 06:37:21PM +0000, Glauber de Oliveira Costa wrote:
> In filesystems with the meta block group flag on, ext3_bg_num_gdb()
> fails to report the correct number of blocks used to store the group
> descriptor backups in a given group. It happens because meta_bg
> follows a different logic from the original ext3 backup placement
> in groups multiples of 3, 5 and 7.

> --- a/fs/ext3/balloc.c
> +++ b/fs/ext3/balloc.c
> @@ -1510,9 +1529,15 @@ int ext3_bg_has_super(struct super_block
> */
> unsigned long ext3_bg_num_gdb(struct super_block *sb, int group)
> {
> - if (EXT3_HAS_RO_COMPAT_FEATURE(sb,EXT3_FEATURE_RO_COMPAT_SPARSE_SUPER)&&
> - !ext3_group_sparse(group))
> - return 0;
> - return EXT3_SB(sb)->s_gdb_count;
> + unsigned long first_meta_bg =
> + cpu_to_le32(EXT3_SB(sb)->s_es->s_first_meta_bg);
> + unsigned long metagroup = group / EXT3_DESC_PER_BLOCK(sb);
> +
> + if (!EXT3_HAS_INCOMPAT_FEATURE(sb,EXT3_FEATURE_INCOMPAT_META_BG)
> + || metagroup < first_meta_bg)
^^^^^^^^^^^^^^^^^^^^^^^^^

Comparison between little-endian and host-endian variables.

> + return ext3_bg_num_gdb_nometa(sb,group);
> +
> + return ext3_bg_num_gdb_meta(sb,group);

-
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