scsi_debug version 1.61

I have reworked the scsi_debug driver mainly to add
kernel timers to simulate delayed responses. This is
more realistic that returning immediately and allows
commands to become queued. The length of the delay is
controlled by a new boot line/module option: "scsi_debug_delay".

Other changes:
  - support REPORT LUNS
  - support more MODE SENSE pages
  - [following Doug Ledford's suggestion] do autsense
    (i.e. set Scsi_Cmnd::sense_buffer array appropriately
     when a status of CHECK CONDITION is set)
  - minor driverfs support
  - start adding error injection logic, see
    "scsi_debug_every_nth"

At the moment the only driverfs support is creating the
directory: /driverfs/bus/scsi/drivers/scsi_debug
Patrick Mochel sent a patch to lkml that would have allowed
driver parameters to be placed in that directory. That patch
didn't make it into lk 2.5.26 .

I'm interested in "clean" ways to inject errors. This would
allow, for example, people to observe (and fix) what happens
when QUEUE_FULL is returned for the first queued command.

The attachment is a patch against lk 2.5.26 . The full driver
and some documentation can be found at 
http://www.torque.net/sg/sdebug.html

I hope to backport this version to lk 2.4 (where it will become
scsi_debug version 0.61) shortly.

Doug Gilbert