// create file system
int mksfs(int fresh){

    // allocate disk space
    int result;
    char *filename = "Simple File System";
    int block_size = MY_BLOCK_SIZE;
    int num_blocks = MY_NUM_BLOCK;

    if (fresh == 1) {
        result = init_fresh_disk(filename, block_size, num_blocks);
    } else {
        result = init_disk(filename, block_size, num_blocks);
    }

    // create partition : super block
    super_block* sb = malloc(1 * sizeof(super_block));
    sb->magic = 0;
    sb->block_size = block_size;
    sb->file_system_size = num_blocks * block_size;
    sb->i_node_table_length = INODE_TABLE_LENGTH;
    write_blocks(SUPER_BLOCK_INDEX, SUPER_BLOCK_LENGTH, sb);

    // create partition : i-node table
    inode* it_buffer = malloc(INODE_TABLE_LENGTH * sizeof(inode));
    write_blocks(INODE_TABLE_INDEX, INODE_TABLE_LENGTH, it_buffer);

    // create partition : directory table, it stores filename->inode pairs
    filename_to_inode* dt_buffer = malloc(INODE_TABLE_LENGTH * sizeof(inode));
    write_blocks(DIRECTORY_TABLE_INDEX, DIRECTORY_TABLE_LENGTH, dt_buffer);

    // create partition : data blocks

    // rest : free bitmap


    // cache inode table to memory
    cached_inode_table = malloc(INODE_TABLE_LENGTH * block_size);
    read_blocks(INODE_TABLE_INDEX, INODE_TABLE_LENGTH, cached_inode_table);

    // cache directory table into memory
    cached_directory_table = malloc(DIRECTORY_TABLE_LENGTH * block_size);
    read_blocks(DIRECTORY_TABLE_INDEX, DIRECTORY_TABLE_LENGTH, cached_directory_table);


    return result;
}