Hello SCSI tapers,

Attached is a patch to add some functionality the st driver so that you 
can monitor the most recent SCSI command and sense buffer.  This info is 
made available via sysfs attributes.  I want to add these attributes in 
order to do better error processing in some custom tape software which I 
am writing.  This patch has been tested on Linux kernel 2.6.12.

The new functionality is as follows:

1) the most recent "relevant" SCSI command and sense are stored in hex 
format in:

   /sys/class/scsi_tape/stN/last_cmnd
   /sys/class/scsi_tape/stN/last_sense

When I say "relevant" SCSI command, I mean: occasionally the most recent 
SCSI command is not the one of interest, e.g. when encountering an ILI, 
the driver will automatically backspace to the beginning of the block. 
However, the last_cmnd and last_sense will show the results of the read 
error, not the backspace.

2) The raw sense data is also decoded into English language for primary 
sense key, extended sense, and ILI/FM/EOM flags in these sysfs files:

   /sys/class/scsi_tape/stN/primary_sense
   /sys/class/scsi_tape/stN/extended_sense
   /sys/class/scsi_tape/stN/sense_flags

Details of implementation:

1) added data fields "last_cmnd" and "last_sense" to struct st_cmdstatus 
for storage of most recent command and sense data.  Removed unused 
"last_cmnd" and "last_sense" fields from struct scsi_tape.

2) added routine st_record_last_command() to save command and sense data

3) added calls to st_record_last_command() in appropriate locations in 
the code.

4) added arg to st_int_ioctl() to indicate whether or not to record the 
SCSI command (necessary so that we can record the "relevant" command)

5) added routines for sysfs attribute files

This is my first time submitting a patch to the list, please go easy on me!!

Regards,

--Andy Stevens
Electrical Science, Inc.
NY, USA