什么是“struct file_operations”参数？

我正在实现一个Linux字符设备驱动程序。

linux / fs.h头文件列出了没有参数名称的file_operations。

例如

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 (*write) (struct file *, const char __user *, size_t, loff_t *); ssize_t (*aio_read) (struct kiocb *, const struct iovec *, unsigned long, loff_t); ssize_t (*aio_write) (struct kiocb *, const struct iovec *, unsigned long, loff_t); int (*readdir) (struct file *, void *, filldir_t); unsigned int (*poll) (struct file *, struct poll_table_struct *); long (*unlocked_ioctl) (struct file *, unsigned int, unsigned long); long (*compat_ioctl) (struct file *, unsigned int, unsigned long); int (*mmap) (struct file *, struct vm_area_struct *); int (*open) (struct inode *, struct file *); int (*flush) (struct file *, fl_owner_t id); int (*release) (struct inode *, struct file *); int (*fsync) (struct file *, loff_t, loff_t, 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 (*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); int (*check_flags)(int); int (*flock) (struct file *, int, struct file_lock *); ssize_t (*splice_write)(struct pipe_inode_info *, struct file *, loff_t *, size_t, unsigned int); ssize_t (*splice_read)(struct file *, loff_t *, struct pipe_inode_info *, size_t, unsigned int); int (*setlease)(struct file *, long, struct file_lock **); long (*fallocate)(struct file *file, int mode, loff_t offset, loff_t len); }; 

哪些文件告诉我每个参数是什么？ 有些是显而易见的，但有些则不是。 如果可以的话，我更喜欢参考官方文档，但是我找不到它。

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• Linux内核头文件的组织
• Linux内核中的主要页面error handling程序
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• 用于基本数据types的copy_to_user（）和copy_from_user（）

例如

 int (*fsync) (struct file *, loff_t, loff_t, int datasync); 

有两个loff_t参数。 我怎么知道他们做什么？

我一直在谷歌search和阅读设备驱动程序的书，但我找不到任何文件，解释什么是争论。 其中一些论点也从LDD3编写时起就有所改变。