Question about the function "spec_freeblks" in 5.4

[Bowen Zhou]

Hello, everyone.

I happened to see the code of "spec_freeblks" , and I am curious if
the code works in real world? In  my opinion, it means to delete the
content of blocks in special files. But I don't think it can finish
this destination actually.

Am I right? Cause as a newcomer to the source code, I am not quite
confident about myself.
Waiting for your advice.

Thanks.