Writing A Disk-Based File-System For The Linux Kernel V2.4

The free blocks list contains indexes of disk blocks that were once allocated and then freed.
No need to hold all free blocks, since we have the number of the highest allocated block in the super-block.
Each entry is 4 bytes long, and thus we have 1024/4 (256) entries for free blocks.
When allocating a data block, we first scan the free list. Only if it is empty, we allocate the next highest non-allocated block.
If we free 257 blocks without allocating any.... BOOM!

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