From: Douglas Gilbert <dougg@torque.net>

The patch only touches two files: scsi.h and scsi_lib.c
It adds the proposed facility and then uses it in scsi_lib
in roughly 4 locations. IMO there were 3 sense processing errors:
   - block SG_IO did not get passed back deferred errors
     [SG_IO is a __pass-through__ interface!!]
   - MEDIUM_ERRORs _do_ get processed for deferred sense errors
     in scsi_io_completion() which seems unintended
     [I did not fix this one.]
   - invalid command operation code handling in
     __scsi_mode_sense() was just wrong

If people think this is a reasonable approach, then the rest of
the scsi mid-level and upper level driver could be converted.
As Kai pointed we may need some general routines to pick up the
sense data "extras".

The benefit of doing this conversion is that it may well
highlight a lot more sense data processing errors (if the
above is any guide).

Changes:
    - add structure to receive normalized sense data from either
      fixed or descriptor format sense data
    - add scsi_normalize_sense() function to populate that structure
    - add scsi_sense_is_deferred() function so deferred errors can
      be ignored in many contexts
    - apply new mechanism to sense data processing within the
      scsi_lib.c file

Patch reformatted by: Christoph Hellwig <hch@lst.de>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>