Hi All, This is just a heads-up for anyone wanting to run btrfs with arm64.

When creating a new btrfs volume there is an option, sectorsize, which is by default set to the current PAGE_SIZE. If one tries to mount btrfs with a PAGE_SIZE != sectorsize, it will fail to mount and the following will be found in dmesg: BTRFS: Incompatible sector size

This should obviously be a cause for concern for those who intend to create a btrfs volume running at one PAGE_SIZE (for instance an installer kernel with 4K), and mounting it with a different PAGE_SIZE (i.e. when running a server kernel with 64K).

There is some work being done by Chandan Rajendra at IBM to fix this: http://comments.gmane.org/gmane.comp.file-systems.btrfs/38808

I've not tried it yet, but will do soon.

Cheers, -- Steve