correct me if i'm wrong, but /data/data isn't the same as /datadata, and you might be referring to /datadata
Looking in the directory of /data/data using root explorer, i don't see anything about free space left, unlike when browsing just the /data directory. (at least for my sensation)
Also, i could be completely wrong about this too, as i haven't had much experience with /data/data and /datadata.
"If we amplify everything, nothing is heard."