generic: Add copy to new file test

This test copies data from various points in a source file to a new
file.  This is useful for testing the basics of copy_file_range().

Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Eryu Guan <eguan@redhat.com>
4 files changed