Which file system automatically stores hashes of files?

"Sun's ZFS does:

With ZFS, all data and metadata is
checksummed using a user-selectable
algorithm. Traditional file systems
that do provide checksumming have
performed it on a per-block basis, out
of necessity due to the volume
management layer and traditional file
system design. The traditional design
means that certain failure modes, such
as writing a complete block to an
incorrect location, can result in
properly checksummed data that is
actually incorrect. ZFS checksums are
stored in a way such that these
failure modes are detected and can be
recovered from gracefully. All
checksumming and data recovery is done
at the file system layer, and is
transparent to applications.

And so does Linux's btrfs: Btrfs also supports both data and metadata checksumming. Data checksumming is optional and can be disabled by mounting with -o nodatasum."