Special inodes¶
ext4 reserves some inode for special features, as follows:
| inode Number | Purpose |
|---|---|
| 0 | Doesn’t exist; there is no inode 0. |
| 1 | List of defective blocks. |
| 2 | Root directory. |
| 3 | User quota. |
| 4 | Group quota. |
| 5 | Boot loader. |
| 6 | Undelete directory. |
| 7 | Reserved group descriptors inode. (“resize inode”) |
| 8 | Journal inode. |
| 9 | The “exclude” inode, for snapshots(?) |
| 10 | Replica inode, used for some non-upstream feature? |
| 11 | Traditional first non-reserved inode. Usually this is the lost+found directory. See s_first_ino in the superblock. |