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 {