the compressed file attribute

[Pat LaVarre <p.lavarre@ieee.org>]

Does one of the Linux fs, other than ntfs, already let me distinguish
one file from another by a compressed attribute?  What I'm hoping to
find is:

Uncompressed files work same as always.

Compressed files appear to work same as always, but under the covers the
data of the file occupies more or less space according to how
compressible it is.  Random access within the file either sequentially
rewrites all the file or else garbage collects and defragments.

I ask here because I think Google mostly points me to file systems that
compress all files e.g. fs/cramfs/README Future Development doesn't
mention this twist, e.g. `ls fs | egrep -i nw5` is empty, ...

Compressing all files is not the same thing.  I don't want the file
system deciding for me which files to compress.

Pat LaVarre