https://launchpad.net/~yofel/+archive/btrfs has an up to date package for btrfs-tools with this functionality. The package in Precise appears to be a snapshot from June 2010.
# dpkg -i btrfs-tools_0.19+20120421-0daily6~bzr457~precise1_amd64.deb
(Reading database ... 108869 files and directories currently installed.)
Preparing to replace btrfs-tools 0.19+20100601-3ubuntu3 (using btrfs-tools_0.19+20120421-0daily6~bzr457~precise1_amd64.deb) ...
Unpacking replacement btrfs-tools ...
Setting up btrfs-tools (0.19+20120421-0daily6~bzr457~precise1) ...
Processing triggers for man-db ...
# btrfs subvolume snapshot -r /export/ftp /export/ftp/.snapshot/hardy
Create a readonly snapshot of '/export/ftp' in '/export/ftp/.snapshot/hardy'
https:/ /launchpad. net/~yofel/ +archive/ btrfs has an up to date package for btrfs-tools with this functionality. The package in Precise appears to be a snapshot from June 2010.
# dpkg -i btrfs-tools_ 0.19+20120421- 0daily6~ bzr457~ precise1_ amd64.deb 3ubuntu3 (using btrfs-tools_ 0.19+20120421- 0daily6~ bzr457~ precise1_ amd64.deb) ... 0daily6~ bzr457~ precise1) ... ftp/.snapshot/ hardy ftp/.snapshot/ hardy'
(Reading database ... 108869 files and directories currently installed.)
Preparing to replace btrfs-tools 0.19+20100601-
Unpacking replacement btrfs-tools ...
Setting up btrfs-tools (0.19+20120421-
Processing triggers for man-db ...
# btrfs subvolume snapshot -r /export/ftp /export/
Create a readonly snapshot of '/export/ftp' in '/export/