"Chris Mason announced version 0.10 of his new Btrfs filesystem,
listing the following new features, 'explicit back references,
online resizing (including shrinking), in place conversion from
Ext3 to Btrfs, data=ordered support, mount options to disable data
COW and checksumming, and barrier support for sata and IDE drives.'
He noted that the disk format in v0.10 has changed, and is not
compatible with the v0.9 disk format. Regarding back reference
support, Chris explained, 'the core of this release is explicit
back references for all metadata blocks, data extents, and
directory items. These are a crucial building block for future
features such as online fsck and migration between devices. The
back references are verified during deletes, and the extent back
references are checked by the existing offline fsck tool...'"