[RFC improve performance for CoW]

I guided by http://goo.gl/tgqL8n
For rsync added --inplace, also added --no-whole-file,
--dalay-updates deleted (conflict with --inplace).
But i don't know how this affect for NoCoW fs.
To cp  added --reflink=auto - this reduce time to create failsafe recovery copy, safe on NoCoW
in my case dir=1.5G on ssd,btrfs
cp -a : 18s
cp -a --reflink=auto : 1.7s