[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#