clone ioctl return values

[Christoph Hellwig]

On Tue, Nov 17, 2015 at 08:57:45AM -0500, Chris Mason wrote:
> > > Errrgh, the golden output of this test reflects the changes to the input
> > > checking in Anna/Peng's copy_file_range/clone_file_range patches.
> > > 
> > > So, I guess the question is, should I reset the golden output to whatever
> > > btrfs spits out before that patchset, and we'll consider the alterations
> > > to be bugs/regressions/whatever that ought to be fixed in their patches?
> > 
> > Some bits in btrfs don't seem kosher.  But it would be good to
> > explicitly send patches for btrfs to adopt to what might make more
> > sense, and then follow it in the other implementations.
> 
> Btrfs does check for directories, but we should really be checking for
> regular files too.  In the end, we only copy extents that would
> correspond with regular files, so we're sneaking by.

Yes, I saw that.  So so far I'd suggest something like the following
for btrfs:

 - return EBADFD for missing read/wite permissions
 - return EINVAL for wrong non-directory file types as the
   source fd

And then make the test case and other implementations match this.

Does this sound like a plan?