1 .. SPDX-License-Identifier: GPL-2.0 1 .. SPDX-License-Identifier: GPL-2.0
2 2
3 Special inodes 3 Special inodes
4 -------------- 4 --------------
5 5
6 ext4 reserves some inode for special features, 6 ext4 reserves some inode for special features, as follows:
7 7
8 .. list-table:: 8 .. list-table::
9 :widths: 6 70 9 :widths: 6 70
10 :header-rows: 1 10 :header-rows: 1
11 11
12 * - inode Number 12 * - inode Number
13 - Purpose 13 - Purpose
14 * - 0 14 * - 0
15 - Doesn't exist; there is no inode 0. 15 - Doesn't exist; there is no inode 0.
16 * - 1 16 * - 1
17 - List of defective blocks. 17 - List of defective blocks.
18 * - 2 18 * - 2
19 - Root directory. 19 - Root directory.
20 * - 3 20 * - 3
21 - User quota. 21 - User quota.
22 * - 4 22 * - 4
23 - Group quota. 23 - Group quota.
24 * - 5 24 * - 5
25 - Boot loader. 25 - Boot loader.
26 * - 6 26 * - 6
27 - Undelete directory. 27 - Undelete directory.
28 * - 7 28 * - 7
29 - Reserved group descriptors inode. (“r 29 - Reserved group descriptors inode. (“resize inode”)
30 * - 8 30 * - 8
31 - Journal inode. 31 - Journal inode.
32 * - 9 32 * - 9
33 - The “exclude” inode, for snapshots( 33 - The “exclude” inode, for snapshots(?)
34 * - 10 34 * - 10
35 - Replica inode, used for some non-upstre 35 - Replica inode, used for some non-upstream feature?
36 * - 11 36 * - 11
37 - Traditional first non-reserved inode. U !! 37 - Traditional first non-reserved inode. Usually this is the lost+found directory. See s\_first\_ino in the superblock.
38 38
39 Note that there are also some inodes allocated <<
40 for other filesystem features which are not re <<
41 hierarchy. These are generally reference from <<
42 <<
43 .. list-table:: <<
44 :widths: 20 50 <<
45 :header-rows: 1 <<
46 <<
47 * - Superblock field <<
48 - Description <<
49 <<
50 * - s_lpf_ino <<
51 - Inode number of lost+found directory. <<
52 * - s_prj_quota_inum <<
53 - Inode number of quota file tracking pro <<
54 * - s_orphan_file_inum <<
55 - Inode number of file tracking orphan in <<
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