On Mon, Mar 06, 2017 at 11:27:23AM -0500, Olga Kornievskaia wrote: > I don’t see copy_file_range() specifying that 0 means end of the file. Is there a reason that copy_file_range shouldn't be like read? (From read(2): "On success, the number of bytes read is returned (zero indicates end of file)". I haven't checked, but suspect that's already true of the implementations we have. Also, from copy_file_range(): EINVAL Requested range extends beyond the end of the source file; or the flags argument is not 0. Some filesystems do this, some don't; I think the man page should make it clear that this behavior is not required. --b.