Final Year Project: Using Linux Filesystems Under Windows   Chris Bryden BEng. Electronics and Software Engineering    School of Computer Science   University of Birmingham 15 3.3.4  The Block and Inode Bitmaps The filesystem uses these bitmaps to keep track of allocated blocks and inodes  within  each  group  on  the  filesystem.  The  block  and  inode  bitmaps  for each group are located at the beginning of each group, after the superblock and group  descriptors.  Each  bit  in  the  bitmap  refers  to  a  block  or  inode  within  the group, a value of 1 indicates that the block or inode has been allocated, and 0 indicates that it is free. The bits are ordered from the first inode or block in the group to the last. To examine the allocation status of a specific block or inode, the group that it belongs to first has to be identified. Once this has been done, the bit for the block or inode is located within the block or inode bitmap for that group. It’s allocation status can then be determined.