Create a hardlink to an open inode

Question

I deleted an ext3 file by accident. But I had a (fresh) backup copy so I put it back.

Unfortunately the file was opened at the time of deletion, so now it exists in 2 copies: the visible copy and the invisible copy. The invisible copy is still written to and it's going to be deleted once the file is closed.

Is it possible to undelete the invisible copy?

Answer 1

The answer is to copy proc/{pid}/fd/{handle} file. The handle can be found by lsof and other means.