RCM6700 Determine Free Flash Space

Is there some way to determine how much flash space is still available on a RCM6700? I have not found a function which would return the free or used space, or even the total space for that matter yet.  

 I have a program and am trying to get the remote update via upload from a webpage working, and my program is only 300kB or so. But every time I try to upload a file greater than 100kB I get the -ENOSPC error from my buTempWrite() function. So I'm trying to figure out where the problem is, but its hard when you don't know how much space is free vs used! And by what 

 

 On a related question, once I do figure out how much space is there, is there a way to clean up the flash memory to get back some of the used space if it is filled with junk data?