file-posix: Implement bdrv_co_copy_range

With copy_file_range(2), we can implement the bdrv_co_copy_range
semantics.

Signed-off-by: Fam Zheng <famz@redhat.com>
Message-id: 20180601092648.24614-6-famz@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
3 files changed