On Fri, Sep 30, 2016 at 12:51:41AM -0700, Christoph Hellwig wrote:

On Thu, Sep 29, 2016 at 08:10:14PM -0700, Darrick J. Wong wrote:

quoted

Define two VFS functions which allow userspace to reflink a range of
blocks between two files or to reflink one file's contents to another.
These functions fit the new VFS ioctls that standardize the checking
for the btrfs CLONE and CLONE RANGE ioctls.

FYI, I really believe the way forward is to make sure vfs_copy_range
calls the clone handler first if present and handles all the differences
between the two.  The only thing that held me back from doing that
is the complete lack of test coverage for the copy functionality.

I've been pondering if there's some way to leverage the existing pile of
clone/clonerange interface tests for copy_file_range without essentially
duplicating all the existing generic/* clone tests, but this time calling
c_f_r instead of _cp_reflink or _reflink_range.  OTOH maybe it's good to
keep them separate since they are separate interfaces.

--D

Otherwise this looks fine to me:

Reviewed-by: Christoph Hellwig <hch@lst.de>