Add more dynamic tracepoints to help debug copy_file_range (copychunk)
and clone_range ("duplicate extents").  These are tracepoints for
entering the function and completing without error. For example:

  "trace-cmd record -e smb3_copychunk_enter -e smb3_copychunk_done"

or

  "trace-cmd record -e smb3_clone_enter -e smb3_clone_done"

Here is sample output:

       TASK-PID     CPU#  |||||  TIMESTAMP  FUNCTION
         | |         |   |||||     |         |
       cp-5964    [005] .....  2176.168977: smb3_clone_enter:
         xid=17 sid=0xeb275be4 tid=0x7ffa7cdb source fid=0x1ed02e15
         source offset=0x0 target fid=0x1ed02e15 target offset=0x0
         len=0xa0000
       cp-5964    [005] .....  2176.170668: smb3_clone_done:
         xid=17 sid=0xeb275be4 tid=0x7ffa7cdb source fid=0x1ed02e15
         source offset=0x0 target fid=0x1ed02e15 target offset=0x0
         len=0xa0000
Reviewed-by: Shyam Prasad N <sprasad@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>