DIF does not work with 6-byte commands so we previously ignored those
commands when preparing a request.  However, DIX does not need
RDPROTECT/WRPROTECT to be set and 6-byte commands are consequently
perfectly valid in host-only mode.
This patch fixes a problem where we would set the wrong DIX operation
when issuing commands to a legacy disk.
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Matthew Wilcox <willy@linux.intel.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
        else
                csum_convert = 0;
 
+       BUG_ON(dif && (scmd->cmnd[0] == READ_6 || scmd->cmnd[0] == WRITE_6));
+
        switch (scmd->cmnd[0]) {
+       case READ_6:
        case READ_10:
        case READ_12:
        case READ_16:
 
                break;
 
+       case WRITE_6:
        case WRITE_10:
        case WRITE_12:
        case WRITE_16: