struct file_operations {
    struct module *owner;
     loff_t(*llseek) (struct file *, loff_t, int);
     ssize_t(*read) (struct file *, char __user *, size_t, loff_t *);
     ssize_t(*aio_read) (struct kiocb *, char __user *, size_t,
    loff_t);
     ssize_t(*write) (struct file *, const char __user *, size_t,
    loff_t *);
     ssize_t(*aio_write) (struct kiocb *, const char __user *, size_t,
          loff_t);
    int (*readdir) (struct file *, void *, filldir_t);
    unsigned int (*poll) (struct file *, struct poll_table_struct *);
    int (*ioctl) (struct inode *, struct file *, unsigned int,
          unsigned long);
    int (*mmap) (struct file *, struct vm_area_struct *);
    int (*open) (struct inode *, struct file *);
    int (*flush) (struct file *);
    int (*release) (struct inode *, struct file *);
    int (*fsync) (struct file *, struct dentry *, int datasync);
    int (*aio_fsync) (struct kiocb *, int datasync);
    int (*fasync) (int, struct file *, int);
    int (*lock) (struct file *, int, struct file_lock *);
     ssize_t(*readv) (struct file *, const struct iovec *, unsigned
    long,
      loff_t *);
     ssize_t(*writev) (struct file *, const struct iovec *, unsigned
    long,
       loff_t *);
     ssize_t(*sendfile) (struct file *, loff_t *, size_t,
    read_actor_t,
         void __user *);
     ssize_t(*sendpage) (struct file *, struct page *, int, size_t,
         loff_t *, int);
    unsigned long (*get_unmapped_area) (struct file *, unsigned long,
        unsigned long, unsigned long,
        unsigned long);
};