New ext4 features

Revision as of 23:58, 11 December 2006 (view source) Mathur (Talk | contribs)		Latest revision as of 02:12, 26 August 2019 (view source) Adilger (Talk | contribs) (update with recent features)
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−	'''Multiblock Allocation'''	+	== Introduction ==
		+
		+	This page contains information about new ext4 features which are currently under development.
		+
		+	For a description of Ext4 features as they appeared in the original 2.6.28 kernel when ext4 was first released, please see the [http://kernelnewbies.org/Ext4 Ext4 Kernelnewbies article].
		+
		+	== Currently being worked on ==
		+
		+	=== Online Directory Shrink ===
		+
		+	* Primary developer: Harshad Shirwadkar
		+	* Status: In progress
		+	* Latest patches: https://lore.kernel.org/linux-ext4/20190824023110.GB19348@mit.edu/T/#t
		+	* e2fsprogs changes: Should not be needed with large directory support
		+	* Outstanding issues: only shrinks if last block in directory is empty, needs to handle arbitrary empty blocks
		+
		+	== Done ==
		+
		+	=== Multiblock Allocation ===
	* Primary developer: Alex Tomas		* Primary developer: Alex Tomas
−	* Status: Patches available	+	* Status: Done
	* Changes on-disk format: No		* Changes on-disk format: No
−	* Target Date: ?
	* e2fsprogs changes: No		* e2fsprogs changes: No
		+	* Outstanding issues: None
−	'''Delayed Allocation'''	+	=== [[DelayedAllocation|Delayed Allocation]] ===
	* Primary developer: Alex Tomas		* Primary developer: Alex Tomas
−	* Status: Patches available	+	* Status: Done
	* Changes on-disk format: No		* Changes on-disk format: No
−	* Target Date: ?
	* e2fsprogs changes: No		* e2fsprogs changes: No
		+	* Outstanding issues: None
−	'''Break 32000 subdirectory limit'''	+	=== Exceed 32000 subdirectory limit ===
−	* Primary developer: Andreas? Ted?	+	* Primary developer: Andreas Dilger
−	* Status: Patches available	+	* Status: Done
	* Changes on-disk format: Yes		* Changes on-disk format: Yes
−	* Target Date: ?	+	* e2fsprogs changes: done
		+	* Outstanding issues: None
		+
		+	=== directory Inodes reservation ===
		+
		+	* Primary developer: Coly
		+	* Status: Patch available
		+	* Changes on-disk format: No
	* e2fsprogs changes: Needed		* e2fsprogs changes: Needed
		+	* Outstanding issues:
−	'''nsec timestamps'''	+	=== nsec timestamps ===
−	* Primary developer: Andreas? Alex?	+	* Primary developer: Andreas Dilger
−	* Status: Patches available	+	* Status: Done
	* Change on-disk format: Yes		* Change on-disk format: Yes
−	* Target Date: ?	+	* e2fsprogs changes: Done
−	* e2fsprogs changes: Needed	+	* Outstanding issues:
−	'''inode version on disk'''	+	=== inode version on disk ===
−	* Primary developer: ?	+	* Primary developer: Jean-Noel Cordenner, Kalpak Shah
−	* Status: Prototype available	+	* Status: Done
	* Change on-disk format: Yes		* Change on-disk format: Yes
−	* Target Date: ?	+	* e2fsprogs changes: None
−	* e2fsprogs changes: Needed	+	* Outstanding issues: None
−	'''uninitialized groups'''	+	=== uninitialized block groups ===
−	* Primary developer: ?	+	* Primary developer: Andreas Dilger
−	* Status: Prototype available	+	* Status: Done
	* Change on-disk format: Yes		* Change on-disk format: Yes
−	* Target Date: ?	+	* e2fsprogs changes: Done
−	* e2fsprogs changes: Needed	+	* Outstanding issues: None
−	'''journal checksumming'''	+	=== journal checksumming ===
−	* Primary developer: Andreas?	+	* Primary developer: Darrick Wong
	* Status: Prototype available		* Status: Prototype available
	* Change on-disk format: Yes		* Change on-disk format: Yes
−	* Target Date: ?	+	* e2fsprogs changes: Done
−	* e2fsprogs changes: Needed	+	* Outstanding issues: None
−	'''persistent preallocation'''	+	=== persistent preallocation (fallocate) ===
−	* Primary developer: Suparna?	+	* Primary developer: Amit Arora, Suparna
−	* Status: In development	+	* Status: Done
	* Change on-disk format: Yes		* Change on-disk format: Yes
−	* Target Date: ?	+	* e2fsprogs changes: complete
−	* e2fsprogs changes: Needed	+	* Outstanding issues:
		+
		+	=== Online Defragmentation ===
		+
		+	* Primary developer: Takashi Sato
		+	* Status: Done
		+	* Related discussions
		+	ext3 online defrag:
		+	http://marc.theaimsgroup.com/?l=linux-fsdevel&m=116160640814410&w=2
		+	* Dependencies: Multiple block allocation from Alex Thomas
		+	* Change on-disk format: No
		+	* e2fsprogs changes: No
		+	* Outstanding issues:
		+
		+	=== First Class [[Quota]] Support ===
		+
		+	* Primary developer: Aditya Kali
		+	* Status: Done
		+	* Design document: [[Design For 1st Class Quota in Ext4]]
		+	* e2fsprogs changes: Done
		+	* Outstanding issues: None
		+
		+	=== Big Allocation Blocks ===
		+
		+	* Primary developer: Theodore Ts'o
		+	* Status: Done
		+	* Design document: [[Design for Big Allocation Blocks]]
		+	* e2fsprogs changes: Done
		+	* Outstanding issues: None
		+
		+	=== Metadata Checksums ===
		+
		+	* Primary developer: Darrick J. Wong
		+	* Status: Done
		+	* Design document: [[Ext4_Metadata_Checksums|Design for Metadata Checksums]]
		+	* e2fsprogs changes: Done
		+	* Disk format change needed: Minor tweaks to existing structures.  Old code will still be able to mount read-only.  tune2fs/e2fsck generally can make the changes without problems.
		+	* Outstanding issues: None
		+
		+	=== Large file support ===
		+
		+	* Primary Developer: Takashi Sato
		+	* status: Done
		+	* Change on-disk format:
		+	* e2fsprogs Changes: Done
		+	* Outstanding issues:
		+
		+	=== Large directory support ===
		+
		+	* Primary Developer: Liang Zhen, Artem Blagodarenko
		+	* status: Done
		+	* Change on-disk format: increase maximum htree level to 3, allow directories over 2GB
		+	* e2fsprogs Changes: Done
		+	* Outstanding issues: None

---

Latest revision as of 02:12, 26 August 2019

Contents 1 Introduction 2 Currently being worked on 2.1 Online Directory Shrink 3 Done 3.1 Multiblock Allocation 3.2 Delayed Allocation 3.3 Exceed 32000 subdirectory limit 3.4 directory Inodes reservation 3.5 nsec timestamps 3.6 inode version on disk 3.7 uninitialized block groups 3.8 journal checksumming 3.9 persistent preallocation (fallocate) 3.10 Online Defragmentation 3.11 First Class Quota Support 3.12 Big Allocation Blocks 3.13 Metadata Checksums 3.14 Large file support 3.15 Large directory support

[edit] Introduction

This page contains information about new ext4 features which are currently under development.

For a description of Ext4 features as they appeared in the original 2.6.28 kernel when ext4 was first released, please see the Ext4 Kernelnewbies article.

[edit] Currently being worked on

[edit] Online Directory Shrink

• Primary developer: Harshad Shirwadkar
• Status: In progress
• Latest patches: https://lore.kernel.org/linux-ext4/20190824023110.GB19348@mit.edu/T/#t
• e2fsprogs changes: Should not be needed with large directory support
• Outstanding issues: only shrinks if last block in directory is empty, needs to handle arbitrary empty blocks

[edit] Done

[edit] Multiblock Allocation

• Primary developer: Alex Tomas
• Status: Done
• Changes on-disk format: No
• e2fsprogs changes: No
• Outstanding issues: None

[edit] Delayed Allocation

• Primary developer: Alex Tomas
• Status: Done
• Changes on-disk format: No
• e2fsprogs changes: No
• Outstanding issues: None

[edit] Exceed 32000 subdirectory limit

• Primary developer: Andreas Dilger
• Status: Done
• Changes on-disk format: Yes
• e2fsprogs changes: done
• Outstanding issues: None

[edit] directory Inodes reservation

• Primary developer: Coly
• Status: Patch available
• Changes on-disk format: No
• e2fsprogs changes: Needed
• Outstanding issues:

[edit] nsec timestamps

• Primary developer: Andreas Dilger
• Status: Done
• Change on-disk format: Yes
• e2fsprogs changes: Done
• Outstanding issues:

[edit] inode version on disk

• Primary developer: Jean-Noel Cordenner, Kalpak Shah
• Status: Done
• Change on-disk format: Yes
• e2fsprogs changes: None
• Outstanding issues: None

[edit] uninitialized block groups

• Primary developer: Andreas Dilger
• Status: Done
• Change on-disk format: Yes
• e2fsprogs changes: Done
• Outstanding issues: None

[edit] journal checksumming

• Primary developer: Darrick Wong
• Status: Prototype available
• Change on-disk format: Yes
• e2fsprogs changes: Done
• Outstanding issues: None

[edit] persistent preallocation (fallocate)

• Primary developer: Amit Arora, Suparna
• Status: Done
• Change on-disk format: Yes
• e2fsprogs changes: complete
• Outstanding issues:

[edit] Online Defragmentation

• Primary developer: Takashi Sato
• Status: Done
• Related discussions

 ext3 online defrag:
 http://marc.theaimsgroup.com/?l=linux-fsdevel&m=116160640814410&w=2

• Dependencies: Multiple block allocation from Alex Thomas
• Change on-disk format: No
• e2fsprogs changes: No
• Outstanding issues:

[edit] First Class Quota Support

• Primary developer: Aditya Kali
• Status: Done
• Design document: Design For 1st Class Quota in Ext4
• e2fsprogs changes: Done
• Outstanding issues: None

[edit] Big Allocation Blocks

• Primary developer: Theodore Ts'o
• Status: Done
• Design document: Design for Big Allocation Blocks
• e2fsprogs changes: Done
• Outstanding issues: None

[edit] Metadata Checksums

• Primary developer: Darrick J. Wong
• Status: Done
• Design document: Design for Metadata Checksums
• e2fsprogs changes: Done
• Disk format change needed: Minor tweaks to existing structures. Old code will still be able to mount read-only. tune2fs/e2fsck generally can make the changes without problems.
• Outstanding issues: None

[edit] Large file support

• Primary Developer: Takashi Sato
• status: Done
• Change on-disk format:
• e2fsprogs Changes: Done
• Outstanding issues:

[edit] Large directory support

• Primary Developer: Liang Zhen, Artem Blagodarenko
• status: Done
• Change on-disk format: increase maximum htree level to 3, allow directories over 2GB
• e2fsprogs Changes: Done
• Outstanding issues: None