typedef struct inode <Impl, Isa> impl file {
    uint    dev;        // Device number
    uint    inum;       // Inode number
    int     ref;        // Reference count
    int     flags;      // I_BUSY, I_VALID

    short   type;       // copy of disk inode
    short   major;
    short   minor;
    short   nlink;
    uint    size;
    uint    addrs[NDIRECT+1];
} inode;