Use the first block from the disk as the superblock followed by the inodeblocks that contain the inodes followed by freebitmap blocks, and the rest for free blocks, datablocks, and indirect blocks.

The superblock contains global information about the file system. Number of inodeblocks and number of freebitmap blocks are preserved in the superblock. Also in the first 4 bytes, it keeps a predefined number (called magic number) that helps you determine if you have a legitimate file system on a disk or not.

To avoid wasting space, ufsdisk packs as many inodes as will fit into an inodeblock. Ufsdisk inodes contain information about the number of blocks in the virtual block store, and is filled with REFS_PER_INODE block pointers:

• The top (REFS_PER_INODE - 3) pointers are direct pointers. A direct pointer points to a datablock
• (REFS_PER_INODE - 2)th pointer is a singly indirect pointer: points to an indirblock that then point to datablock(s).
• (REFS_PER_INODE -1)th pointer is a doubly indirect pointer: points to an indirblock that points to other indirblock(s) that then point to datablock(s).
• (REFS_PER_INODE)th pointer is a triply indirect pointer: points to an indirblock that points to other indirblock(s) that points to other indirblock(s) then point to datablock(s).

You can find more information about direct and indirect pointers in your textbook.

A freebitmap block is a block of bits that is used to keep track of free blocks in the file system. Each bit in a freebitmap block corresponds to a block in the "remaining blocks" section of the layout. A value of 0 indicates that the block is not used, and a value of 1 indicates that the block is in use. Freebitmap blocks do not keep bits to track the status of superblock, inodes, or the other freebitmap blocks.