56 lines
1.4 KiB
ReStructuredText
56 lines
1.4 KiB
ReStructuredText
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.. SPDX-License-Identifier: GPL-2.0
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Special inodes
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--------------
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ext4 reserves some inode for special features, as follows:
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.. list-table::
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:widths: 6 70
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:header-rows: 1
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* - inode Number
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- Purpose
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* - 0
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- Doesn't exist; there is no inode 0.
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* - 1
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- List of defective blocks.
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* - 2
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- Root directory.
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* - 3
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- User quota.
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* - 4
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- Group quota.
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* - 5
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- Boot loader.
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* - 6
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- Undelete directory.
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* - 7
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- Reserved group descriptors inode. (“resize inode”)
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* - 8
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- Journal inode.
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* - 9
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- The “exclude” inode, for snapshots(?)
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* - 10
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- Replica inode, used for some non-upstream feature?
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* - 11
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- Traditional first non-reserved inode. Usually this is the lost+found directory. See s\_first\_ino in the superblock.
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Note that there are also some inodes allocated from non-reserved inode numbers
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for other filesystem features which are not referenced from standard directory
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hierarchy. These are generally reference from the superblock. They are:
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.. list-table::
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:widths: 20 50
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:header-rows: 1
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* - Superblock field
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- Description
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* - s\_lpf\_ino
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- Inode number of lost+found directory.
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* - s\_prj\_quota\_inum
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- Inode number of quota file tracking project quotas
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* - s\_orphan\_file\_inum
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- Inode number of file tracking orphan inodes.
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