On-Disk Format Changes Ahead To Improve "Painful" Parts Of Btrfs Design
Over the next year Josef is looking to land these changes to address locking contention on global roots and the issue of block group items being spread throughout the extent tree.
He is developing this work under the "extent-tree-v2" label and to date is around 80 patches but is just getting started. He's hoping in the next 6~12 months it will be something users can start migrating to in order to take advantage of these Btrfs design improvements.
With this work yielding on-disk format changes, users will need to convert their Btrfs file-systems to the updated format but in turn lose support for mounting the file-system on older kernels. Some users at first may also be understandably a bit nervous about altering the on-disk format, but hopefully the new version will prove to be a useful (and reliable) improvement.
More details on these improvements coming to the Btrfs file-system design can be found over on Josef's blog.