[ext4]06 磁盘布局 - 特殊inode

Ext4预留了一些inode做特殊特性使用，见下表：

inode	Purpose
0	不存在，Ext4中不存在inode 0.
1	存放损坏的数据块链表
2	根目录
3	User quota. 用户quota索引
4	Group quota. 组quota索引
5	Boot loader.
6	Undelete directory. 未删除的目录
7	预留的块组描述符inode. (用于调整inode数目)
8	日志inode索引
9	The "exclude" inode, for snapshots(?)
10	Replica inode, used for some non-upstream feature?
11	第一个非预留的inode，通常是lost+found目录，s_first_ino in the superblock.

root@ubuntu:/mnt/ext4# hexdump -C -s 1445888 -n 256/dev/sdc

/* (Inode 1, 存放损坏的数据链表) */

00161000 0000 00 00 00 00 00 00 e3 9e 2a 53 e3 9e2a 53 |..........*S..*S|

00161010 e39e 2a 53 00 00 00 00 00 00 00 00 00 0000 00 |..*S............|

00161020 0000 00 00 00 00 00 00 00 00 00 00 00 0000 00 |................|

*

00161100

root@ubuntu:/mnt/ext4# hexdump -C -s 1446144 -n 256/dev/sdc

/* (Inode 2， 根目录) */

00161100 ed41 00 00 00 10 00 00 5f 9c 2b 53 47 9c2b 53 |.A......_.+SG.+S|

00161110 479c 2b 53 00 00 00 00 00 00 03 00 08 0000 00 |G.+S............|

00161120 0000 08 00 02 00 00 00 0a f3 01 00 04 0000 00 |................|

00161130 0000 00 00 00 00 00 00 01 00 00 00 61 2100 00 |............a!..|

00161140 0000 00 00 00 00 00 00 00 00 00 00 00 0000 00 |................|

*

00161180 1c00 00 00 58 2e b0 1f 58 2e b0 1f 80 3117 bc |....X...X....1..|

00161190 e39e 2a 53 00 00 00 00 00 00 00 00 00 0000 00 |..*S............|

001611a0 0000 00 00 00 00 00 00 00 00 00 00 00 0000 00 |................|

*

00161200

root@ubuntu:/mnt/ext4# hexdump -C -s 1446400 -n 256/dev/sdc

/* (Inode 3， user quota) */

00161200 0000 00 00 00 00 00 00 00 00 00 00 00 0000 00 |................|

*

00161300

root@ubuntu:/mnt/ext4# hexdump -C -s 1446656 -n 256/dev/sdc

/* (Inode 4，group quota) */

00161300 0000 00 00 00 00 00 00 00 00 00 00 00 0000 00 |................|

*

00161400

root@ubuntu:/mnt/ext4# hexdump -C -s 1446912 -n 256/dev/sdc

/* (Inode 5，Boot Loader) */

00161400 0000 00 00 00 00 00 00 00 00 00 00 00 0000 00 |................|

*

00161500

root@ubuntu:/mnt/ext4# hexdump -C -s 1447168 -n 256/dev/sdc

/* (Inode 6， 未删除的目录) */

00161500 0000 00 00 00 00 00 00 00 00 00 00 00 0000 00 |................|

*

00161600

root@ubuntu:/mnt/ext4# hexdump -C -s 1447424 -n 256/dev/sdc

/* (Inode 7，预留的用于存放块组描述符的的inode) */

00161600 8081 00 00 00 c0 40 00 e3 9e 2a 53 e3 9e2a 53 |......@...*S..*S|

00161610 e39e 2a 53 00 00 00 00 00 00 01 00 c8 4f00 00 |..*S.........O..|

00161620 0000 00 00 00 00 00 00 00 00 00 00 00 0000 00 |................|

*

00161650 0000 00 00 00 00 00 00 00 00 00 00 66 2100 00 |............f!..|

00161660 0000 00 00 00 00 00 00 00 00 00 00 01 0000 00 |................|

00161670 0000 00 00 00 00 00 00 00 00 00 00 00 0000 00 |................|

00161680 1c00 00 00 00 00 00 00 00 00 00 00 00 0000 00 |................|

00161690 e39e 2a 53 00 00 00 00 00 00 00 00 00 0000 00 |..*S............|

001616a0 0000 00 00 00 00 00 00 00 00 00 00 00 0000 00 |................|

*

00161700

root@ubuntu:/mnt/ext4# hexdump -C -s 1447680 -n 256/dev/sdc

/* (Inode 8，日志索引) */

00161700 8081 00 00 00 00 00 08 e4 9e 2a 53 e4 9e2a 53 |..........*S..*S|

00161710 e49e 2a 53 00 00 00 00 00 00 01 00 00 0004 00 |..*S............|

00161720 0000 08 00 00 00 00 00 0a f3 02 00 04 0000 00 |................|

00161730 0000 00 00 00 00 00 00 ff 7f 00 00 00 8008 00 |................|

00161740 ff7f 00 00 01 00 00 00 ff ff 08 00 00 0000 00 |................|

00161750 0000 00 00 00 00 00 00 00 00 00 00 00 0000 00 |................|

*

00161780 1c00 00 00 00 00 00 00 00 00 00 00 00 0000 00 |................|

00161790 e49e 2a 53 00 00 00 00 00 00 00 00 00 0000 00 |..*S............|

001617a0 0000 00 00 00 00 00 00 00 00 00 00 00 0000 00 |................|

*

00161800

root@ubuntu:/mnt/ext4# hexdump -C -s 1447936 -n 256/dev/sdc

/* (Inode 9) */

00161800 0000 00 00 00 00 00 00 00 00 00 00 00 0000 00 |................|

*

00161900

root@ubuntu:/mnt/ext4# hexdump -C -s 1448192 -n 256/dev/sdc

/* (Inode 10) */

00161900 0000 00 00 00 00 00 00 00 00 00 00 00 0000 00 |................|

*

00161a00

root@ubuntu:/mnt/ext4# hexdump -C -s 1448448 -n 256/dev/sdc

/* (Inode 11，第一个非预留的inode，通常是lost+found，s_first_ino in the superblock) */

00161a00 c041 00 00 00 40 00 00 e3 9e 2a 53 e3 9e2a 53 |.A...@....*S..*S|

00161a10 e39e 2a 53 00 00 00 00 00 00 02 00 20 0000 00 |..*S........ ...|

00161a20 0000 08 00 00 00 00 00 0a f3 01 00 04 0000 00 |................|

00161a30 0000 00 00 00 00 00 00 04 00 00 00 62 2100 00 |............b!..|

00161a40 0000 00 00 00 00 00 00 00 00 00 00 00 0000 00 |................|

*

00161a80 1c00 00 00 00 00 00 00 00 00 00 00 00 00 0000 |................|

00161a90 e39e 2a 53 00 00 00 00 00 00 00 00 00 0000 00 |..*S............|

00161aa0 0000 00 00 00 00 00 00 00 00 00 00 00 0000 00 |................|

*

00161b00

root@ubuntu:/mnt/ext4#