Re: [PATCH 1/1] [RFC] 64bit copy_file_range system call

["J. Bruce Fields" <bfields@fieldses.org>]

On Sat, Jun 17, 2017 at 08:09:38AM -0700, Christoph Hellwig wrote:
> On Sat, Jun 17, 2017 at 08:42:54AM -0400, Olga Kornievskaia wrote:
> > 
> > > On Jun 17, 2017, at 6:03 AM, Christoph Hellwig <hch@infradead.org> wrote:
> > > 
> > > On Fri, Jun 16, 2017 at 01:36:30PM -0400, J. Bruce Fields wrote:
> > >> It makes a difference in the clone case, doesn't it?  (Though I'd think
> > >> best there would be a special "copy to end of file" value.)
> > > 
> > > Clones uses a 0 length as "whole" file.  Both for the NFS operation
> > > and the Linux ioctl.
> > 
> > Does that actually work? There is  check vfs_copy_file_range()
> 
> Please re-read the above sentence.  I'm talking about NFS clone and
> IOC_CLONE_RANGE, not copy_file_range.  copy_file_range had to follow
> the NFS semantics that don't have the special 0 case.

Nope, COPY has it:

	https://tools.ietf.org/html/rfc7862#section-15.2.3

	A count of 0 (zero) requests that all bytes from ca_src_offset
	through EOF be copied to the destination.

I think leaving it out of copy_file_range was just an oversight.

--b.