freeing up NULL-led space in tmpfs

[Attila Nagy]

Hi,

ZFS with compression enabled has a great feature: if you write NULLs(\0) 
to an already existing file, it will make it sparse and free up the 
NULL-ed space.
I regurarly depend on this feature, but now I would need this on 
machines with no disks.

Creating zpools on md is not too convenient, having this feature in 
tmpfs would be the best.

Any chance that somebody works on it, or finds this a good candidate to 
work on?

Thanks,