How to get checksum data integrity on ext4?

Ext4 doesn't have an equivalent to a ZFS or btrfs "scrub", however, a recent feature is metadata checksumming. Using it would require a very new kernel and an updated e2fsprogs.

What distribution are you using?

@ewwhite answer is correct. I just want to stress that: NO - data cannot be checksummed in ext4 or XFS at this time. I also couldn't find anything related to checksumming for JFS. So the only reliable option so far is to check linux ZFS. BTRFS is not so stable at this time.

I'm writing the above because I've just hit bad silent write corruption on my router vs USB external drive and now I do not anymore trust USB as a reliable interconnect. So additional checksumming is required. (and I mean that the drive is completely healthy but router USB is flacky)