[CentOS] block level changes at the file system level?

I'm trying to streamline a backup system using ZFS. In our situation, 
we're writing pg_dump files repeatedly, each file being highly similar 
to the previous file. Is there a file system (EG: ext4? xfs?) that, when 
re-writing a similar file, will write only the changed blocks and not 
rewrite the entire file to a new set of blocks?

Assume that we're writing a 500 MB file with only 100 KB of changes. 
Other than a utility like diff, is there a file system that would only 
write 100KB and not 500 MB of data? In concept, this would work 
similarly to using the 'diff' utility...

-Ben