This is essentially the same patch sent 6 weeks ago:
   http://marc.info/?l=linux-scsi&m=137943733409512&w=2
re-based on '[PATCH v2] sg: O_EXCL and other lock handling'.

ChangeLog:
     - remove the 16 byte CDB (SCSI command) length limit
       from the sg driver by handling longer CDBs the same
       way as the bsg driver. Remove comment from sg.h
       public interface about the cmd_len field being
       limited to 16 bytes.

Signed-off-by: Douglas Gilbert <dgilbert@interlog.com>