linux内核源代码include/linux/fs.h中关键的和设备驱动程序有关的结构

struct file_operations结构位置：

linux内核源代码中include目录中linux目录fs.h中

1. struct file_operations {
   
2. struct module *owner;
   
3. loff_t (*llseek) (struct file *, loff_t, int);
   
4. ssize_t (*read) (struct file *, char __user *, size_t, loff_t *);
   
5. ssize_t (*aio_read) (struct kiocb *, char __user *, size_t, loff_t);
   
6. ssize_t (*write) (struct file *, const char __user *, size_t, loff_t *);
   
7. ssize_t (*aio_write) (struct kiocb *, const char __user *, size_t, loff_t);
   
8. int (*readdir) (struct file *, void *, filldir_t);
   
9. unsigned int (*poll) (struct file *, struct poll_table_struct *);
   
10. int (*ioctl) (struct inode *, struct file *, unsigned int, unsigned long);
    
11. long (*unlocked_ioctl) (struct file *, unsigned int, unsigned long);
    
12. long (*compat_ioctl) (struct file *, unsigned int, unsigned long);
    
13. int (*mmap) (struct file *, struct vm_area_struct *);
    
14. int (*open) (struct inode *, struct file *);
    
15. int (*flush) (struct file *);
    
16. int (*release) (struct inode *, struct file *);
    
17. int (*fsync) (struct file *, struct dentry *, int datasync);
    
18. int (*aio_fsync) (struct kiocb *, int datasync);
    
19. int (*fasync) (int, struct file *, int);
    
20. int (*lock) (struct file *, int, struct file_lock *);
    
21. ssize_t (*readv) (struct file *, const struct iovec *, unsigned long, loff_t *);
    
22. ssize_t (*writev) (struct file *, const struct iovec *, unsigned long, loff_t *);
    
23. ssize_t (*sendfile) (struct file *, loff_t *, size_t, read_actor_t, void *);
    
24. ssize_t (*sendpage) (struct file *, struct page *, int, size_t, loff_t *, int);
    
25. unsigned long (*get_unmapped_area)(struct file *, unsigned long, unsigned long, unsigned long, unsigned long);
    
26. int (*check_flags)(int);
    
27. int (*dir_notify)(struct file *filp, unsigned long arg);
    
28. int (*flock) (struct file *, int, struct file_lock *);
    
29. ssize_t (*splice_write)(struct pipe_inode_info *, struct file *, loff_t *, size_t, unsigned int);
    
30. ssize_t (*splice_read)(struct file *, loff_t *, struct pipe_inode_info *, size_t, unsigned int);
    
31. };

linux/fs.h中定义的struct file是设备驱动程序使用的第二个最重要的数据结构：

file结构代表一个打开的文件（不仅仅限定于设备驱动程序，系统中每个打开的文件在内核空间都有一个对应的file结构），它由内核在open时创建，并传递给在改文件上进行操作的所有函数，直到最后的close函数，在文件的所有实例都关闭后，内核会释放这个数据结构。

内核源代码中，指向struct file的指针通常被称为file或者filp

1. struct file {
   
2. /*
   
3.     * fu_list becomes invalid after file_free is called and queued via
   
4.     * fu_rcuhead for RCU freeing
   
5.     */
   
6. 
   
7. union {
   
8.        struct list_head fu_list;
   
9.        struct rcu_head     fu_rcuhead;
   
10. } f_u;
    
11. 
    
12. struct dentry        *f_dentry; //文件对应的目录项结构
    
13. 
    
14. struct vfsmount       *f_vfsmnt;
    
15. 
    
16. const struct file_operations *f_op; //与文件相关的操作
    
17. 
    
18. atomic_t        f_count;
    
19. 
    
20. unsigned int       f_flags;   //文件标志，如O_RDONLY,O_NONBLOCK和O_SYNC
    
21. 
    
22. mode_t          f_mode;        //文件模式
    
23. 
    
24. loff_t          f_pos; //当前读写位置
    
25. 
    
26. struct fown_struct f_owner;
    
27. 
    
28. unsigned int        f_uid, f_gid;
    
29. 
    
30. struct file_ra_state f_ra;
    
31. 
    
32. unsigned long        f_version;
    
33. 
    
34. void          *f_security;
    
35. 
    
36. /* needed for tty driver, and maybe others */
    
37. void          *private_data;
    
38. 
    
39. #ifdef CONFIG_EPOLL
    
40. /* Used by fs/eventpoll.c to link all the hooks to this file */
    
41. struct list_head f_ep_links;
    
42. spinlock_t        f_ep_lock;
    
43. #endif /* #ifdef CONFIG_EPOLL */
    
44. 
    
45. struct address_space *f_mapping;
    
46. };
    
47. extern spinlock_t files_lock;

内核用inode结构在内部表示文件，因此它和file结构不痛，后者表示打开的文件描述符，对单个文件，可能会有许多个表示打开的文件描述符的file结构，但是他们都指向单个inode结构。

inode结构包含了大量有关文件的信息，作为常规，只有下面2个字段对编写驱动程序代码有用：

1. dev_t i_rdev;
   
2. 
   
3. //对表示设备文件的inode结构，改字段包含了真正的设备编号。
   
4. 
   
5. struct cdev   *i_cdev；
   
6. //struct cdev是表示字符设备的内核的内部结构，当inode指向一个字符设备文件时，该字段包含了指向struct cdev结构的指针。
   
7. 
   
8. struct inode {
   
9. struct hlist_node i_hash;
   
10. struct list_head i_list;
    
11. struct list_head i_sb_list;
    
12. struct list_head i_dentry;
    
13. unsigned long        i_ino;
    
14. atomic_t        i_count;
    
15. umode_t          i_mode;
    
16. unsigned int        i_nlink;
    
17. uid_t          i_uid;
    
18. gid_t          i_gid;
    
19. dev_t          i_rdev;
    
20. loff_t          i_size;
    
21. struct timespec        i_atime;
    
22. struct timespec        i_mtime;
    
23. struct timespec        i_ctime;
    
24. unsigned int        i_blkbits;
    
25. unsigned long        i_blksize;
    
26. unsigned long        i_version;
    
27. blkcnt_t        i_blocks;
    
28. unsigned short       i_bytes;
    
29. spinlock_t        i_lock; /* i_blocks, i_bytes, maybe i_size */
    
30. struct mutex        i_mutex;
    
31. struct rw_semaphore i_alloc_sem;
    
32. struct inode_operations *i_op;
    
33. const struct file_operations *i_fop; /* former ->i_op->default_file_ops */
    
34. struct super_block *i_sb;
    
35. struct file_lock *i_flock;
    
36. struct address_space *i_mapping;
    
37. struct address_space i_data;
    
38. #ifdef CONFIG_QUOTA
    
39. struct dquot        *i_dquot[MAXQUOTAS];
    
40. #endif
    
41. /* These three should probably be a union */
    
42. struct list_head i_devices;
    
43. struct pipe_inode_info *i_pipe;
    
44. struct block_device *i_bdev;
    
45. struct cdev        *i_cdev;
    
46. int          i_cindex;
    
47. 
    
48. __u32          i_generation;
    
49. 
    
50. #ifdef CONFIG_DNOTIFY
    
51. unsigned long        i_dnotify_mask; /* Directory notify events */
    
52. struct dnotify_struct *i_dnotify; /* for directory notifications */
    
53. #endif
    
54. 
    
55. #ifdef CONFIG_INOTIFY
    
56. struct list_head inotify_watches; /* watches on this inode */
    
57. struct mutex        inotify_mutex; /* protects the watches list */
    
58. #endif
    
59. 
    
60. unsigned long        i_state;
    
61. unsigned long        dirtied_when; /* jiffies of first dirtying */
    
62. 
    
63. unsigned int        i_flags;
    
64. 
    
65. atomic_t        i_writecount;
    
66. void          *i_security;
    
67. union {
    
68.        void        *generic_ip;
    
69. } u;
    
70. #ifdef __NEED_I_SIZE_ORDERED
    
71. seqcount_t        i_size_seqcount;
    
72. #endif
    
73. }；