2.6.36中struct file_operations 的变化

最近在做Linux驱动方面的东西。发现涉及到.ioctl部分存在着问题。我的电脑是2.6.32.127的内核，这个用起来没有问题。而我把它放到2.6.36的内核中就有了问题，报错为.ioctl不存在。我特意查了源码中的相关定义，发现2.6.36中少了

int (*ioctl) (struct inode *, struct file *, unsigned int, unsigned long);

这一行，而仅剩下

 long (*unlocked_ioctl) (struct file *, unsigned int, unsigned long);
 long (*compat_ioctl) (struct file *, unsigned int, unsigned long);

这两行关于ioctl操作的函数

 

在这种情况下，我们只能用long (*unlocked_ioctl) (struct file *, unsigned int, unsigned long);来替换掉之前的int (*ioctl) (struct inode *, struct file *, unsigned int, unsigned long);但是还是存在着问题，即他们的返回值是不同的。

unlocked_ioctl: long ioctl(struct file *filp, unsigned int cmd, unsigned long args);

old ioctl: int ioctl(struct inode *inode, struct file *filp, unsigned int cmd, unsigned long args);

同时unlocked_ioctl去除了"inode" 函数指针(which can be obtained anyways through the filp),

另外The 'inode' value that was passed to 'ioctl' function is available for use with the 'unlocked_ioctl' function by way of filp->d_entry->d_inode:
    long (*unlocked_ioctl) (struct file *filp, unsigned int cmd, unsigned long arg);
    ...
    struct inode *inode = filp->d_entry->d_inode;

There is a nice explanation of this at http://lwn.net/Articles/119652/

 

其在几个版本中的具体定义如下：

 

2.6.36的fs.h中file_operations 定义

#define HAVE_COMPAT_IOCTL 1
#define HAVE_UNLOCKED_IOCTL 1

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 *, 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 **);
};

 

2.6.34版本的fs.h这里如下

1480 // 
1481 // NOTE: 
1482 // read, write, poll, fsync, readv, writev, unlocked_ioctl and compat_ioctl 
1483 // can be called without the big kernel lock held in all filesystems. 
1484 // 
1485 struct file_operations {  
1486         struct module *owner;  
1487         loff_t (*llseek) (struct file *, loff_t, int);  
1488         ssize_t (*read) (struct file *, char __user *, size_t, loff_t *);  
1489         ssize_t (*write) (struct file *, const char __user *, size_t, loff_t *);  
1490         ssize_t (*aio_read) (struct kiocb *, const struct iovec *, unsigned long, loff_t);  
1491         ssize_t (*aio_write) (struct kiocb *, const struct iovec *, unsigned long, loff_t);  
1492         int (*readdir) (struct file *, void *, filldir_t);  
1493         unsigned int (*poll) (struct file *, struct poll_table_struct *);  
1494         int (*ioctl) (struct inode *, struct file *, unsigned int, unsigned long);  
1495         long (*unlocked_ioctl) (struct file *, unsigned int, unsigned long);  
1496         long (*compat_ioctl) (struct file *, unsigned int, unsigned long);  
1497         int (*mmap) (struct file *, struct vm_area_struct *);  
1498         int (*open) (struct inode *, struct file *);  
1499         int (*flush) (struct file *, fl_owner_t id);  
1500         int (*release) (struct inode *, struct file *);  
1501         int (*fsync) (struct file *, struct dentry *, int datasync);  
1502         int (*aio_fsync) (struct kiocb *, int datasync);  
1503         int (*fasync) (int, struct file *, int);  
1504         int (*lock) (struct file *, int, struct file_lock *);  
1505         ssize_t (*sendpage) (struct file *, struct page *, int, size_t, loff_t *, int);  
1506         unsigned long (*get_unmapped_area)(struct file *, unsigned long, unsigned long, unsigned long, unsigned long);  
1507         int (*check_flags)(int);  
1508         int (*flock) (struct file *, int, struct file_lock *);  
1509         ssize_t (*splice_write)(struct pipe_inode_info *, struct file *, loff_t *, size_t, unsigned int);  
1510         ssize_t (*splice_read)(struct file *, loff_t *, struct pipe_inode_info *, size_t, unsigned int);  
1511         int (*setlease)(struct file *, long, struct file_lock **);  
1512 }; 

2.6.32.2的fs.h中file_operations 定义

//These macros are for out of kernel modules to test that
// the kernel supports the unlocked_ioctl and compat_ioctl
// fields in struct file_operations.
#define HAVE_COMPAT_IOCTL 1
#define HAVE_UNLOCKED_IOCTL 1

//
// NOTE:
// read, write, poll, fsync, readv, writev, unlocked_ioctl and compat_ioctl
 // can be called without the big kernel lock held in all filesystems.
 //
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 *);
 int (*ioctl) (struct inode *, struct file *, unsigned int, unsigned long);
 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 *, 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 (*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 **);
};

 

转自：http://blog.sina.com.cn/s/blog_5f8665e70100p46z.html