xref: /linux/Documentation/filesystems/ext4/special_inodes.rst (revision 48dea9a700c8728cc31a1dd44588b97578de86ee)
1.. SPDX-License-Identifier: GPL-2.0
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3Special inodes
4--------------
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6ext4 reserves some inode for special features, as follows:
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8.. list-table::
9   :widths: 6 70
10   :header-rows: 1
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12   * - inode Number
13     - Purpose
14   * - 0
15     - Doesn't exist; there is no inode 0.
16   * - 1
17     - List of defective blocks.
18   * - 2
19     - Root directory.
20   * - 3
21     - User quota.
22   * - 4
23     - Group quota.
24   * - 5
25     - Boot loader.
26   * - 6
27     - Undelete directory.
28   * - 7
29     - Reserved group descriptors inode. (“resize inode”)
30   * - 8
31     - Journal inode.
32   * - 9
33     - The “exclude” inode, for snapshots(?)
34   * - 10
35     - Replica inode, used for some non-upstream feature?
36   * - 11
37     - Traditional first non-reserved inode. Usually this is the lost+found directory. See s\_first\_ino in the superblock.
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