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Ext4 Developer Interlock Call: 05-07-07 Minutes

Attendees: Mingming Cao, Dave Kleikamp, Avantika Mathur, Ted Ts'o, Aneesh Veetil, Takashi Sato, Jose Santos

Discussed pushing ext4 patches to Linus' tree

  • Preallocation Patches: These patches are almost ready to push, once we have consensus from all architecture maintainers on the format of the system call. See if Amit can push these patches in the next day or two, Mingming will help.
  • Nanosecond Timestamps: Ted will take a closer look at this patch before pushing
  • It was proposed to push everything in the ext4 git tree up until the unstable patches. Before pushing these patches, we must run tests on the patches and use the check-patches scripts to perform sanity checking.


  • Ted recently posted e2fsprogs-1.39-tyt3; which includes patches supporting extents. This is a work in progress.
  • Jose had recently asked about creating large filesystems, with the larger block size. He used the patches to e2fsprogs sent by Valerie Clement, and was able to create fs greater than 17TB.
    • Ted suggested that these patches be added to e2fsprogs-tyt3, with a flag set when in use, indicating that no shared libraries should be used.
  • Ted is planning to discontinue use of Mercurial for e2fsprogs, and switch entirely to git. By using git, we can have a stable and development branch for e2fsprogs, and even create separate branches for new topics, that can eventually be merged to the stable branch. This will also reduce the work Ted does to create a patch series.


  • Aneesh looked at the online defragmentation code, and feels it may not be usable for migration because it is solely extents based. Mingming pointed out that the new defrag patches also have support for indirect mapped blocks, Aneesh will look into these new patches.
  • Ted suggested doing the migration through two ioctls, the first migrating the inode online via ioctl, and the second using the online-defrag ioctl.

Meta-Block Groups:

  • Mingming mentioned that in the metablock group feature, the inode metadata is not moved with the rest of the metadata. Ted will check this, as he thought this had been implemented.
  • Online resize does not use metablock groups, and is currently limited to 2TB.
  • Also need to remove sanity checks in the mount code
  • Once these issues are fixed, the metablock group feature can be turned on by default for ext4 filesysytems

The extents option will be turned on by default for all ext4 filesystems with the extents feature enabled.

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