下面是Linux fs 相关数据结构的一些笔记，列出的是我开发中经常用到的一些结构成员，以linux 3.12为例。
struct dentry{
struct dentry *d_parent; /* parent directory */
struct qstr d_name;
struct inode *d_inode; /* Where the name belongs to */
unsigned char d_iname[DNAME_INLINE_LEN]; /* small names */
...
};
dentry: directory entry
detail: http://goo.gl/Lisgeg
struct inode{
unsigned long i_ino;
umode_t i_mode;
const struct file_operations *i_fop;
void *i_security;
...
};
detail: http://goo.gl/TphYHp
inode->i_mode 是 16位整数，下面是8进制表示
#define S_IFMT 00170000
#define S_IFSOCK 0140000
#define S_IFLNK 0120000
#define S_IFREG 0100000
#define S_IFBLK 0060000
#define S_IFDIR 0040000
#define S_IFCHR 0020000
#define S_IFIFO 0010000
#define S_ISUID 0004000
#define S_ISGID 0002000
#define S_ISVTX 0001000
#define S_ISLNK(m) (((m) & S_IFMT) == S_IFLNK)
#define S_ISREG(m) (((m) & S_IFMT) == S_IFREG)
#define S_ISDIR(m) (((m) & S_IFMT) == S_IFDIR)
#define S_ISCHR(m) (((m) & S_IFMT) == S_IFCHR)
#define S_ISBLK(m) (((m) & S_IFMT) == S_IFBLK)
#define S_ISFIFO(m) (((m) & S_IFMT) == S_IFIFO)
#define S_ISSOCK(m) (((m) & S_IFMT) == S_IFSOCK)
#define S_IRWXU 00700
#define S_IRUSR 00400
#define S_IWUSR 00200
#define S_IXUSR 00100
#define S_IRWXG 00070
#define S_IRGRP 00040
#define S_IWGRP 00020
#define S_IXGRP 00010
#define S_IRWXO 00007
#define S_IROTH 00004
#define S_IWOTH 00002
#define S_IXOTH 00001
举例
root@ubuntu:~# ls -il temp.txt
681278 -rw-r--r-- 1 root root 56844 Jul 9 08:46 temp.txt
i_ino = 681278
i_imode = 00644
struct file{
struct path f_path;
unsigned int f_flags; /* 文件属性 */
fmode_t f_mode; /* 文件打开模式 */
struct inode *f_inode;
const struct file_operations *f_op;
const struct cred *f_cred;
void *f_security;
};
detail: http://goo.gl/56ouH4
位于源码/include/linux/fs.h头部
file->f_flags: http://goo.gl/YCkhZq
#define O_ACCMODE 00000003
#define O_RDONLY 00000000
#define O_WRONLY 00000001
#define O_RDWR 00000002
#define O_CREAT 00000100 /* not fcntl */
#define O_EXCL 00000200 /* not fcntl */
#define O_NOCTTY 00000400 /* not fcntl */
#define O_TRUNC 00001000 /* not fcntl */
#define O_APPEND 00002000
#define O_NONBLOCK 00004000
#define O_DSYNC 00010000 /* used to be O_SYNC, see below */
#define FASYNC 00020000 /* fcntl, for BSD compatibility */
#define O_DIRECT 00040000 /* direct disk access hint */
#define O_LARGEFILE 00100000
#define O_DIRECTORY 00200000 /* must be a directory */
#define O_NOFOLLOW 00400000 /* don't follow links */
#define O_NOATIME 01000000
#define O_CLOEXEC 02000000 /* set close_on_exec */
file->f_mode
/*
* flags in file.f_mode. Note that FMODE_READ and FMODE_WRITE must correspond
* to O_WRONLY and O_RDWR via the strange trick in __dentry_open()
*/
/* file is open for reading */
#define FMODE_READ ((__force fmode_t)0x1)
/* file is open for writing */
#define FMODE_WRITE ((__force fmode_t)0x2)
/* file is seekable */
#define FMODE_LSEEK ((__force fmode_t)0x4)
/* file can be accessed using pread */
#define FMODE_PREAD ((__force fmode_t)0x8)
/* file can be accessed using pwrite */
#define FMODE_PWRITE ((__force fmode_t)0x10)
/* File is opened for execution with sys_execve / sys_uselib */
#define FMODE_EXEC ((__force fmode_t)0x20)
/* File is opened with O_NDELAY (only set for block devices) */
#define FMODE_NDELAY ((__force fmode_t)0x40)
/* File is opened with O_EXCL (only set for block devices) */
#define FMODE_EXCL ((__force fmode_t)0x80)
一些文件操作相关函数参数mask的掩码，标识访问文件的方式
#define MAY_EXEC 0x00000001
#define MAY_WRITE 0x00000002
#define MAY_READ 0x00000004
#define MAY_APPEND 0x00000008
#define MAY_ACCESS 0x00000010
#define MAY_OPEN 0x00000020
#define MAY_CHDIR 0x00000040
struct file_operations{
int (*open) (struct inode *, struct file *);
ssize_t (*read) (struct file *, char __user *, size_t, loff_t *);
ssize_t (*write) (struct file *, const char __user *, size_t, loff_t *);
...
};
details: http://goo.gl/oMQuKj
struct path {
struct vfsmount *mnt;
struct dentry *dentry;
};