New ext4 features

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'''Multiblock Allocation'''
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== Introduction ==
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This page contains information about new ext4 features which are currently under development.
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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 ==
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=== First Class [[Quota]] Support ===
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* Primary developer: Aditya Kali
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* Status: In progress
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* Design document: [[Design For 1st Class Quota in Ext4]]
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* e2fsprogs changes: Yes
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* Oustanding issues: None
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=== Big Allocation Blocks ===
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* Primary developer: Theodore Ts'o
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* Status: In progress
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* Design document: [[Design for Big Allocation Blocks]]
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* e2fsprogs changes: Yes, needed
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* Oustanding issues: None
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=== Metadata Checksumming ===
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* Primary developer: Darrick J. Wong
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* Status: In progress
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* Design document: [[Ext4_Metadata_Checksums|Design for Metadata Checksums]]
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* e2fsprogs changes: Yes, needed.
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* 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.
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* Outstanding issues: None
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== Done ==
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=== Multiblock Allocation ===
  
 
* Primary developer: Alex Tomas
 
* Primary developer: Alex Tomas
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* Status: Patches available - ready to push to mainline
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* Status: Done
 
* Changes on-disk format: No
 
* Changes on-disk format: No
 
* Target Date: ?
 
* Target Date: ?
 
* e2fsprogs changes: No
 
* e2fsprogs changes: No
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* outstanding issues: none
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* outstanding issues: None
  
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'''Delayed Allocation'''
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=== [[DelayedAllocation|Delayed Allocation]] ===
  
 
* Primary developer: Alex Tomas
 
* Primary developer: Alex Tomas
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* Status: Patches available
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* Status: Done
 
* Changes on-disk format: No
 
* Changes on-disk format: No
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* Target Date: ?
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* Target Date: (in patch queue)
 
* e2fsprogs changes: No
 
* e2fsprogs changes: No
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* outstanding issues: lack of plan for 1k,2k block size and default data=order mode, and Andrew asked for more comments.
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* outstanding issues: Done
  
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'''Break 32000 subdirectory limit'''
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=== Break 32000 subdirectory limit ===
  
 
* Primary developer: Andreas
 
* Primary developer: Andreas
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* Status: Patches available, need to be resubmitted on ext4
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* Status: Done
 
* Changes on-disk format: Yes
 
* Changes on-disk format: Yes
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* Target Date: ?
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* Target Date: (in patch queue)
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* e2fsprogs changes: Needed
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* e2fsprogs changes: done
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* outstanding issues: unknown
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* outstanding issues: None
  
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'''Inode reservation for directories'''
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=== directory Inodes reservation ===
  
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* Primary developer: Andreas, Coly
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* Primary developer: Coly
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* Status: Prototype available, implementing by Coly with Andreas' guiding
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* Status: Patch available
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* Changes on-disk format: Yes
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* Changes on-disk format: No
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* Target Date: ?
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* Target Date: Nov, 2007
 
* e2fsprogs changes: Needed
 
* e2fsprogs changes: Needed
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* outstanding issues: unknown
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* outstanding issues:  
  
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'''nsec timestamps'''
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=== nsec timestamps ===
  
 
* Primary developer: Andreas
 
* Primary developer: Andreas
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* Status: Patches available, should not need much rework once issues are resolved
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* Status: Done
 
* Change on-disk format: Yes
 
* Change on-disk format: Yes
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* Target Date: ?
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* Target Date: (in patch queue)
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* e2fsprogs changes: Needed
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* e2fsprogs changes: Done
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* outstanding issues: should the feature be available in 128 bit inodes, or only in larger inodes. Performance impact unknown.
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* outstanding issues:
  
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'''inode version on disk'''
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=== inode version on disk ===
  
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* Primary developer: Jean-Noel Cordenner
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* Primary developer: Jean-Noel Cordenner, Kalpak Shah
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* Status: Prototype available
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* Status: Done
 
* Change on-disk format: Yes
 
* Change on-disk format: Yes
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* Target Date: ?
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* Target Date: (in patch queue)
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* e2fsprogs changes: Needed
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* e2fsprogs changes: None
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* outstanding issues: CPU usage
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* outstanding issues: None
  
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'''uninitialized groups'''
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=== uninitialized groups ===
  
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* Primary developer: ?
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* Primary developer: Andreas Dilger
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* Status: Prototype available
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* Status: Done
 
* Change on-disk format: Yes
 
* Change on-disk format: Yes
−
* Target Date: ?
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* Target Date: (in patch queue)
−
* e2fsprogs changes: Needed
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* e2fsprogs changes: Done
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* outstanding issues:
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* outstanding issues: lazy zeroing of unused inode table blocks after filesystem is first mounted
  
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'''journal checksumming'''
+
=== journal checksumming ===
  
 
* Primary developer: Andreas
 
* Primary developer: Andreas
 
* Status: Prototype available
 
* Status: Prototype available
 
* Change on-disk format: Yes
 
* Change on-disk format: Yes
−
* Target Date: ?
+
* Target Date: (in patch queue)
 
* e2fsprogs changes: Needed
 
* e2fsprogs changes: Needed
 
* outstanding issues:
 
* outstanding issues:
  
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'''persistent preallocation'''
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=== persistent preallocation ===
  
 
* Primary developer: Amit Arora, Suparna
 
* Primary developer: Amit Arora, Suparna
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* Status: Patches available and reviewed
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* Status: Done
 
* Change on-disk format: Yes
 
* Change on-disk format: Yes
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* Target Date: Once interface issue is resolved
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* Target Date: (in patch queue)
 
* e2fsprogs changes: complete
 
* e2fsprogs changes: complete
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* outstanding issues: Need consensus on what interface should be used (ioctl, fcntl..), should return value be zero or number of block allocated on success
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* outstanding issues:
  
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'''Online Defragmentation'''
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=== Online Defragmentation ===
  
 
* Primary developer: Takashi Sato
 
* Primary developer: Takashi Sato
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* Change on-disk format: No
 
* Change on-disk format: No
 
* Target Date:  
 
* Target Date:  
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* e2fsprogs changes:  
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* e2fsprogs changes: No
 
* outstanding issues:  
 
* outstanding issues:  
 
    
 
    
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'''Undelete Feature for Ext4'''
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=== Undelete Feature for Ext4 ===
  
 
* Primary Developer:  
 
* Primary Developer:  
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* outstanding issues: Should the kernel be involved with undelete
 
* outstanding issues: Should the kernel be involved with undelete
  
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'''Large file support'''
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=== Large file support ===
  
 
* Primary Developer: Takashi Sato
 
* Primary Developer: Takashi Sato
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* status: Increase 2Tb limit on filesize. Takashi has begun working on this.
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* status: Done
 
* Change on-disk format:
 
* Change on-disk format:
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* Target Date:
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* Target Date: (in patch queue)
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* e2fsprogs Changes:
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* e2fsprogs Changes: Done
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* outstanding issues: unknown
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* outstanding issues:

Revision as of 20:03, 1 February 2013

Contents

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.

Currently being worked on

First Class Quota Support

Big Allocation Blocks

Metadata Checksumming

  • Primary developer: Darrick J. Wong
  • Status: In progress
  • Design document: Design for Metadata Checksums
  • e2fsprogs changes: Yes, needed.
  • 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

Done

Multiblock Allocation

  • Primary developer: Alex Tomas
  • Status: Done
  • Changes on-disk format: No
  • Target Date: ?
  • e2fsprogs changes: No
  • outstanding issues: None

Delayed Allocation

  • Primary developer: Alex Tomas
  • Status: Done
  • Changes on-disk format: No
  • Target Date: (in patch queue)
  • e2fsprogs changes: No
  • outstanding issues: Done

Break 32000 subdirectory limit

  • Primary developer: Andreas
  • Status: Done
  • Changes on-disk format: Yes
  • Target Date: (in patch queue)
  • e2fsprogs changes: done
  • outstanding issues: None

directory Inodes reservation

  • Primary developer: Coly
  • Status: Patch available
  • Changes on-disk format: No
  • Target Date: Nov, 2007
  • e2fsprogs changes: Needed
  • outstanding issues:

nsec timestamps

  • Primary developer: Andreas
  • Status: Done
  • Change on-disk format: Yes
  • Target Date: (in patch queue)
  • e2fsprogs changes: Done
  • outstanding issues:

inode version on disk

  • Primary developer: Jean-Noel Cordenner, Kalpak Shah
  • Status: Done
  • Change on-disk format: Yes
  • Target Date: (in patch queue)
  • e2fsprogs changes: None
  • outstanding issues: None

uninitialized groups

  • Primary developer: Andreas Dilger
  • Status: Done
  • Change on-disk format: Yes
  • Target Date: (in patch queue)
  • e2fsprogs changes: Done
  • outstanding issues: lazy zeroing of unused inode table blocks after filesystem is first mounted

journal checksumming

  • Primary developer: Andreas
  • Status: Prototype available
  • Change on-disk format: Yes
  • Target Date: (in patch queue)
  • e2fsprogs changes: Needed
  • outstanding issues:

persistent preallocation

  • Primary developer: Amit Arora, Suparna
  • Status: Done
  • Change on-disk format: Yes
  • Target Date: (in patch queue)
  • e2fsprogs changes: complete
  • outstanding issues:

Online Defragmentation

  • Primary developer: Takashi Sato
  • Status: 
 latest patch: v0.2 posted on Jan 10th.
 Previous tries:
 http://marc.theaimsgroup.com/?l=linux-ext4&m=116678507906760&w=2
 http://marc.theaimsgroup.com/?l=linux-ext4&m=116307062907075&w=2
  • 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
  • Target Date:
  • e2fsprogs changes: No
  • outstanding issues:

Undelete Feature for Ext4

  • Primary Developer:
  • status: Idea was proposed on the mailing list, still need more thought on the feature.
  • Change on-disk format:
  • Target Date:
  • e2fsprogs changes:
  • outstanding issues: Should the kernel be involved with undelete

Large file support

  • Primary Developer: Takashi Sato
  • status: Done
  • Change on-disk format:
  • Target Date: (in patch queue)
  • e2fsprogs Changes: Done
  • outstanding issues:
Retrieved from "https://ext4.wiki.kernel.org/index.php?title=New_ext4_features&oldid=5961"
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