[PATCHSET] support FSCTL_DUPLICATE_EXTENTS_TO_FILE

[Jeremy Allison]

On Wed, May 10, 2017 at 01:35:36PM +0200, David Disseldorp via samba-technical wrote:
> On Wed, 10 May 2017 13:20:31 +0200, Ralph Böhme via samba-technical wrote:
> 
> > > There are no VFS API stability grantees, it's best-effort. 306783d6f5d5
> > > already makes API 37 significantly different to the previous version,
> > > so I'd prefer to keep the new flags parameter.  
> > 
> > we guarantee to keep it unmodified within a x.y release, but going from x.y to
> > x.y+1 can change it.
> 
> Okay, I wasn't aware. If that is the case, then it's probably something
> that we should put in README.Coding.

Yep, sorry. This is one of those "I thought everyone knew" things :-).

We must keep ABI stability within a x.y release, to keep third party
VFS modules working - moving to x.y+1 is when we can change.