scst: Rework SCSI pass-through support for kernel versions >= 2.6.30

Changes in this patch:
- Rework the SCSI pass-through code such that for kernel versions
  >= 2.6.30 the scst_exec_req_fifo patch is no longer needed.
- Modify the pass-through code such that blk_rq_append_bio() is only
  called for kernel version 2.6.30. For later kernel versions
  blk_make_request() is called instead.
- Rework scst_scsi_exec_async().
- Add debug tracing of SCSI pass-through result status.
- Add a lockdep_assert_held() call in scsi_end_async().



git-svn-id: http://svn.code.sf.net/p/scst/svn/trunk@5979 d57e44dd-8a1f-0410-8b47-8ef2f437770f

scripts/generate-kernel-patch

@@ -282,6 +282,7 @@ for p in scst/kernel/*-${kver}.patch \
 		echo iscsi-scst/kernel/patches/*-${kver}.patch;
 	   fi)
 do
+  [ -e "$p" ] || continue
   # Exclude the put_page_callback patch when command-line option -u has been
   # specified since the current approach is not considered acceptable for
   # upstream kernel inclusion. See also http://lkml.org/lkml/2008/12/11/213.