This is a revised patch following this post:
http://marc.theaimsgroup.com/?l=linux-scsi&m=112461881419898&w=2

The plan is to add MODE SELECT SCSI command support to
libata so that parameters such as WCE and DRA can be
changed by a user (i.e. Write(back) Cache Enable and
Disable Read Ahead respectively). There are still some
issues to be addressed with MODE SELECT so the attached
is mainly a subset of the earlier one.
It improves error processing and fixes a READ_6/WRITE_6
SCSI command special case ** as requested by Jeff G.

The attached is against lk 2.6.13-rc6 and includes the
START STOP UNIT patch.

ChangeLog:
   - generalize SCSI error processing
   - add block descriptor to MODE SENSE command
   - make various changes to sync with sat-r05 (as
     noted in source)
   - fix READ(6) and WRITE(6) SCSI command special
     case: transfer_length=0 -> transfer 256 blocks


** The special case can be tested with sg_dd:
sg_dd if=/dev/sda blk_sgio=1 cdbsz=6 of=. bs=512 bpt=256 count=256
   This tests READ(6) with a transfer length of 0
   (i.e. 256 blocks) in its cdb.
   BTW the scsi_debug driver has the same bug.

Signed-off-by: Douglas Gilbert <dougg@torque.net>

Doug Gilbert