什么是"struct file_operations"参数？

Question

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);
};

文档在哪里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,我更愿意参考官方文档,但我找不到它.

例如

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

有两个loff_t参数.我怎么知道他们做了什么？

我一直在谷歌搜索和阅读设备驱动程序书,但我找不到任何文件来解释争论的内容.从编写LDD3开始,一些论点也发生了变化.

Answer 1

LDD3书籍对于了解大局非常有用,但它对细节没有帮助(对于内核2.6.10,同时我们正在向3.9迈进).该kernelnewbies司机页面也许是最先进的最新,全面的资源.对于日常更改,LWN会定期评估API更改并发布更长时间的新功能概述.H-online包含一系列文章,详细介绍了从内核版本到内核版本的更改,以及指向讨论和补丁的链接.