Go to the previous, next section.

Group Descriptors

On disk, the group descriptors immediately follow the superblock and each descriptor has the following layout:

struct ext2_group_desc
{
  unsigned long  bg_block_bitmap;
  unsigned long  bg_inode_bitmap;
  unsigned long  bg_inode_table;
  unsigned short bg_free_blocks_count;
  unsigned short bg_free_inodes_count;
  unsigned short bg_used_dirs_count;
  unsigned short bg_pad;
  unsigned long  bg_reserved[3];
};

bg_block_bitmap

points to the blocks bitmap block for the group.

bg_inode_bitmap

points to the inodes bitmap block for the group.

bg_inode_table

points to the inodes table first block.

bg_free_blocks_count

number of free blocks in the group.

bg_free_inodes_count

number of free inodes in the group.

bg_used_dirs_count

number of inodes allocated to directories in the group.

bg_pad

padding.

The information in a group descriptor pertains only to the group it is actually describing.

Go to the previous, next section.