[Samba] Samba and BTRFS server-side copy

[Saint Germain]

On Thu, 27 Oct 2016 15:39:27 -0700, Jeremy Allison <jra at samba.org>
wrote :

> On Fri, Oct 28, 2016 at 12:08:50AM +0200, Saint Germain via samba
> wrote:
> > On Thu, 27 Oct 2016 14:50:48 -0700, Jeremy Allison <jra at samba.org>
> > wrote :
> > > 
> > > Server-side copy can be requested using smbclient, using
> > > the "scopy" command.
> > > 
> > > It's a simple:
> > > 
> > > scopy source dest
> > 
> > Thanks but I just tested and it doesn't trigger
> > BTRFS_IOC_CLONE_RANGE. The server-side copy is working all right,
> > but the file is not copied through BTRFS reflink (cp
> > --reflink=auto). It is quite noticeable on large file, where it
> > should be nearly instantaneous.
> > 
> > My configuration:
> >  - client: Debian Stable + smbclient 4.4.6 (coming from Testing) +
> >    kernel 4.7 (amd64)
> >  - server: Debian Stable + samba 4.2.10 + kernel 4.7 (amd64)
> 
> OK, follow though using debug level 10 and see why it isn't
> selecting the reflink code.
> 
> Are you using SMB2 ?

No I was using SMB1: my mistake.
Now with SMB2, it works, thanks !

If I can ask, what is this restrictions with "Btrfs filesystem aligned"
and "FSCTL_SRV_COPYCHUNK wire request byte offsets and lengths align
to the Btrfs sector-size" ?
Is it a restriction on the server or the client ?
How can I check that I don't have this restriction ?

Thanks for your help !