SIze of a file shows 124 GB while available size is less than 16 GB

Hi All, I am working with bionic c(Android). There is a file that I generated which is showing 124 GB(ls -l) size. Whereas the actual available memory on the partition is less than 16 GB. I am trying to debug but unable to reach any conclusion. What could be the possible reason? Has someone seen like this before? Posting it here as I think it has got something to do with linux internals. I am guessing fseek's offset somewhere has gone wrong. But any directions would be very helpful. Regards, Manty