linux

linux informations

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第十五章 Linux核心数据结构 

本章列出了Linux实用的主要数据结构。 


block_dev_struct
此结构用于向核心登记块设备，它还被buffer cache实用。所有此类结构都位于blk_dev数组中。 

struct blk_dev_struct {
    void (*request_fn)(void);
    struct request * current_request;
    struct request   plug;
    struct tq_struct plug_tq;
};
buffer_head
此结构包含关于buffer cache中一块缓存的信息。 

/* bh state bits */
#define BH_Uptodate  0   /* 1 if the buffer contains valid data      */
#define BH_Dirty     1   /* 1 if the buffer is dirty                 */
#define BH_Lock      2   /* 1 if the buffer is locked                */
#define BH_Req       3   /* 0 if the buffer has been invalidated     */
#define BH_Touched   4   /* 1 if the buffer has been touched (aging) */
#define BH_Has_aged  5   /* 1 if the buffer has been aged (aging)    */
#define BH_Protected 6   /* 1 if the buffer is protected             */
#define BH_FreeOnIO  7   /* 1 to discard the buffer_head after IO    */

struct buffer_head {
  /* First cache line: */
  unsigned long      b_blocknr;    /* block number                   */
  kdev_t             b_dev;        /* device (B_FREE = free)         */
  kdev_t             b_rdev;       /* Real device                    */
  unsigned long      b_rsector;    /* Real buffer location on disk   */
  struct buffer_head *b_next;      /* Hash queue list                */
  struct buffer_head *b_this_page; /* circular list of buffers in one 
                                      page                           */

  /* Second cache line: */
  unsigned long      b_state;      /* buffer state bitmap (above)    */
  struct buffer_head *b_next_free;
  unsigned int       b_count;      /* users using this block         */
  unsigned long      b_size;       /* block size                     */

  /* Non-performance-critical data follows. */
  char               *b_data;      /* pointer to data block          */
  unsigned int       b_list;       /* List that this buffer appears  */
  unsigned long      b_flushtime;  /* Time when this (dirty) buffer
                                    * should be written              */
  unsigned long      b_lru_time;   /* Time when this buffer was 
                                    * last used.                     */
  struct wait_queue  *b_wait;
  struct buffer_head *b_prev;      /* doubly linked hash list        */
  struct buffer_head *b_prev_free; /* doubly linked list of buffers  */
  struct buffer_head *b_reqnext;   /* request queue                  */
};
device
系统中每个网络设备都用一个设备数据结构来表示。 

struct device 
{

  /*
   * This is the first field of the "visible" part of this structure
   * (i.e. as seen by users in the "Space.c" file).  It is the name
   * the interface.
   */
  char                    *name;

  /* I/O specific fields                                           */
  unsigned long           rmem_end;        /* shmem "recv" end     */
  unsigned long           rmem_start;      /* shmem "recv" start   */
  unsigned long           mem_end;         /* shared mem end       */
  unsigned long           mem_start;       /* shared mem start     */
  unsigned long           base_addr;       /* device I/O address   */
  unsigned char           irq;             /* device IRQ number    */

  /* Low-level status flags. */
  volatile unsigned char  start,           /* start an operation   */
                          interrupt;       /* interrupt arrived    */
  unsigned long           tbusy;           /* transmitter busy     */
  struct device           *next;

  /* The device initialization function. Called only once.         */
  int                     (*init)(struct device *dev);

  /* Some hardware also needs these fields, but they are not part of
     the usual set specified in Space.c. */
  unsigned char           if_port;         /* Selectable AUI,TP,   */
  unsigned char           dma;             /* DMA channel          */

  struct enet_statistics* (*get_stats)(struct device *dev);

  /*
   * This marks the end of the "visible" part of the structure. All
   * fields hereafter are internal to the system, and may change at
   * will (read: may be cleaned up at will).
   */

  /* These may be needed for future network-power-down code.       */
  unsigned long           trans_start;     /* Time (jiffies) of 
                                              last transmit        */
  unsigned long           last_rx;         /* Time of last Rx      */
  unsigned short          flags;           /* interface flags (BSD)*/
  unsigned short          family;          /* address family ID    */
  unsigned short          metric;          /* routing metric       */
  unsigned short          mtu;             /* MTU value            */
  unsigned short          type;            /* hardware type        */
  unsigned short          hard_header_len; /* hardware hdr len     */
  void                    *priv;           /* private data         */

  /* Interface address info. */
  unsigned char           broadcast[MAX_ADDR_LEN];
  unsigned char           pad;               
  unsigned char           dev_addr[MAX_ADDR_LEN];  
  unsigned char           addr_len;        /* hardware addr len    */
  unsigned long           pa_addr;         /* protocol address     */
  unsigned long           pa_brdaddr;      /* protocol broadcast addr*/
  unsigned long           pa_dstaddr;      /* protocol P-P other addr*/
  unsigned long           pa_mask;         /* protocol netmask     */
  unsigned short          pa_alen;         /* protocol address len */

  struct dev_mc_list      *mc_list;        /* M'cast mac addrs     */
  int                     mc_count;        /* No installed mcasts  */
  
  struct ip_mc_list       *ip_mc_list;     /* IP m'cast filter chain */
  __u32                   tx_queue_len;    /* Max frames per queue   */
    
  /* For load balancing driver pair support */
  unsigned long           pkt_queue;       /* Packets queued       */
  struct device           *slave;          /* Slave device         */
  struct net_alias_info   *alias_info;     /* main dev alias info  */
  struct net_alias        *my_alias;       /* alias devs           */
  
  /* Pointer to the interface buffers. */
  struct sk_buff_head     buffs[DEV_NUMBUFFS];

  /* Pointers to interface service routines. */
  int                     (*open)(struct device *dev);
  int                     (*stop)(struct device *dev);
  int                     (*hard_start_xmit) (struct sk_buff *skb,
                                              struct device *dev);
  int                     (*hard_header) (struct sk_buff *skb,
                                          struct device *dev,
                                          unsigned short type,
                                          void *daddr,
                                          void *saddr,
                                          unsigned len);
  int                     (*rebuild_header)(void *eth, 
                                          struct device *dev,
                                          unsigned long raddr,
                                          struct sk_buff *skb);
  void                    (*set_multicast_list)(struct device *dev);
  int                     (*set_mac_address)(struct device *dev,
                                          void *addr);
  int                     (*do_ioctl)(struct device *dev, 
                                          struct ifreq *ifr,
                                          int cmd);
  int                     (*set_config)(struct device *dev,
                                          struct ifmap *map);
  void                    (*header_cache_bind)(struct hh_cache **hhp,
                                          struct device *dev, 
                                          unsigned short htype,
                                          __u32 daddr);
  void                    (*header_cache_update)(struct hh_cache *hh,
                                          struct device *dev,
                                          unsigned char *  haddr);
  int                     (*change_mtu)(struct device *dev,
                                          int new_mtu);
  struct iw_statistics*   (*get_wireless_stats)(struct device *dev);
};
device_struct
此结构被块设备和字符设备用来向核心登记（包含设备名称以及可对此设备进行的文件操作）。chrdevs和blkdevs 中的每个有效分别表示一个字符设备和块设备。 

struct device_struct {
    const char * name;
    struct file_operations * fops;
};
file
每个打开的文件、套接口都用此结构表示。 

struct file {
  mode_t f_mode;
  loff_t f_pos;
  unsigned short f_flags;
  unsigned short f_count;
  unsigned long f_reada, f_ramax, f_raend, f_ralen, f_rawin;
  struct file *f_next, *f_prev;
  int f_owner;         /* pid or -pgrp where SIGIO should be sent */
  struct inode * f_inode;
  struct file_operations * f_op;
  unsigned long f_version;
  void *private_data;  /* needed for tty driver, and maybe others */
};
files_struct
描叙被某进程打开的所有文件。 

struct files_struct {
  int count;
  fd_set close_on_exec;
  fd_set open_fds;
  struct file * fd[NR_OPEN];
};
fs_struct

struct fs_struct {
  int count;
  unsigned short umask;
  struct inode * root, * pwd;
};
gendisk
包含关于某个硬盘的信息。用于磁盘初始化与分区检查时。 

struct hd_struct {
    long start_sect;
    long nr_sects;
};

struct gendisk {
    int major;               /* major number of driver */
    const char *major_name;  /* name of major driver */
    int minor_shift;         /* number of times minor is shifted to
                                get real minor */
    int max_p;               /* maximum partitions per device */
    int max_nr;              /* maximum number of real devices */

    void (*init)(struct gendisk *); 
                             /* Initialization called before we 
                                do our thing */
    struct hd_struct *part;  /* partition table */
    int *sizes;              /* device size in blocks, copied to 
                                blk_size[] */
    int nr_real;             /* number of real devices */

    void *real_devices;      /* internal use */
    struct gendisk *next;
};
inode
此VFS inode结构描叙磁盘上一个文件或目录的信息。 

struct inode {
    kdev_t                       i_dev;
    unsigned long                i_ino;
    umode_t                      i_mode;
    nlink_t                      i_nlink;
    uid_t                        i_uid;
    gid_t                        i_gid;
    kdev_t                       i_rdev;
    off_t                        i_size;
    time_t                       i_atime;
    time_t                       i_mtime;
    time_t                       i_ctime;
    unsigned long                i_blksize;
    unsigned long                i_blocks;
    unsigned long                i_version;
    unsigned long                i_nrpages;
    struct semaphore             i_sem;
    struct inode_operations      *i_op;
    struct super_block           *i_sb;
    struct wait_queue            *i_wait;
    struct file_lock             *i_flock;
    struct vm_area_struct        *i_mmap;
    struct page                  *i_pages;
    struct dquot                 *i_dquot[MAXQUOTAS];
    struct inode                 *i_next, *i_prev;
    struct inode                 *i_hash_next, *i_hash_prev;
    struct inode                 *i_bound_to, *i_bound_by;
    struct inode                 *i_mount;
    unsigned short               i_count;
    unsigned short               i_flags;
    unsigned char                i_lock;
    unsigned char                i_dirt;
    unsigned char                i_pipe;
    unsigned char                i_sock;
    unsigned char                i_seek;
    unsigned char                i_update;
    unsigned short               i_writecount;
    union {
        struct pipe_inode_info   pipe_i;
        struct minix_inode_info  minix_i;
        struct ext_inode_info    ext_i;
        struct ext2_inode_info   ext2_i;
        struct hpfs_inode_info   hpfs_i;
        struct msdos_inode_info  msdos_i;
        struct umsdos_inode_info umsdos_i;