is cache-only-prefixes an nnpfs limitation?

[Tomas Olsson]

Harald Barth <haba at pdc.kth.se> writes:
> > That means cache eviction of parts of files, and making new holes
> > in files doesn't seem to be widely supported yet.
> 
> Yes. When reading a big file, it must be possible to throw away the
> beginning or middle to be able to fit the end in the cache.
> 
"Big" steps in linux in this area, btw.  They actually added support for
punching holes, but only for tmpfs and shmem IIRC.  And only through
sys_madvise().  Maybe more will come, sys_holepunch(fd, start, len) was
mentioned.

Are there any sane interfaces for this in other OS:es?

/t