[PATCHSET] support FSCTL_DUPLICATE_EXTENTS_TO_FILE

[Christoph Hellwig]

On Thu, May 04, 2017 at 05:54:41PM +0200, David Disseldorp wrote:
> On Thu, 4 May 2017 08:40:00 -0700, Christoph Hellwig wrote:
> 
> > Not directly related to the patch, but IOC_CLONE_RANGE is a core
> > VFS feature in Linux these days and for example support by XFS and NFS
> > as well.  It's somewhat odd to have it in a vfs_btrfs module.
> 
> Yeah, this'll hopefully get moved out of vfs_btrfs soon. A WIP
> syscall(SYS_copy_file_range) patch from Björn is available at:
> https://lists.samba.org/archive/samba-technical/2017-January/118259.html

Don't use copy_file_range if you want to clone.  IOC_CLONE_RANGE is
always the better choice if supported.