I'm sure someone will be along to correct me quick enough if I'm wrong, but last year when I was upgrading to Lion I had the same issue (journaling turned off) and was able to turn it back on with minimal pain by doing it from the Snow Leopard boot disc (Disk Utility, of course).
Unfortunately that just gets me a helpful "Journaling could not be enabled". I guess something got messed up when I was writing to the volume from Linux.
enableJournal device
Enable journaling on an HFS+ volume. This works whether or not
the volume is currently mounted (the volume is temporarily
mounted if necessary). Ownership of the affected disk is
required.
disableJournal [force] device
Disable journaling on an HFS+ volume. This normally works
whether or not the volume is currently mounted (the volume is
temporarily mounted if necessary). If the force option is speci-
fied, then journaling is disabled directly on disk; in this case,
the volume must not be mounted. Ownership of the affected disk
is required.
moveJournal external | internal [journalDevice] device
external will create a 512MB Apple_Journal partition out of
journalDevice and an HFS+ partition will be created out of the
remaining space if available; journalDevice must be a partition,
not a whole-disk. The journal for device will then be moved
externally onto the newly created Apple_Journal partition.
internal will move the journal for device back locally.
I don't know if it can work on the mounted root filesystem so you may want to try that from the recovery partition.
I can't upgrade yet because I disabled HFS+ journaling and nothing seems to be able to re-enable it (the installer requires journaling to be enabled).
[1] http://d43.me/blog/1205/the-cause-for-all-your-mac-os-x-mous...