Trace events target_sequencer_start and target_cmd_complete
(include/trace/events/target.h) are ready to show NAA identifier, LUN ID,
and many other important command details in the system log:

TP_printk("%s -> LUN %03u %s data_length %6u  CDB %s  (TA:%s C:%02x)",

However, it's still hard to identify command on the initiator and command
on the target in the real life output of system log.  For that purpose SCSI
provides a command identifier or task tag (term used in previous
standards). This patch adds tag ID in the system log's output:

TP_printk("%s -> LUN %03u tag %#llx %s data_length %6u  CDB %s  (TA:%s C:%02x)",

kworker/1:1-35    [001] ....  1392.989452: target_sequencer_start:
naa.5001405ec1ba6364 -> LUN 001 tag 0x1
SERVICE_ACTION_IN_16 data_length     32
CDB 9e 10 00 00 00 00 00 00 00 00 00 00 00 20 00 00  (TA:SIMPLE C:00)

kworker/1:1-35    [001] ....  1392.989456: target_cmd_complete:
naa.5001405ec1ba6364 <- LUN 001 tag 0x1 status GOOD (sense len 0)
SERVICE_ACTION_IN_16 data_length     32
CDB 9e 10 00 00 00 00 00 00 00 00 00 00 00 20 00 00  (TA:SIMPLE C:00)

Link: https://lore.kernel.org/r/226e01deaa9baf46d6ff3b8698bc9fe881f7dfc1.camel@dubeyko.comReviewed-by: Roman Bolshakov <r.bolshakov@yadro.com>
Reviewed-by: Konstantin Shelekhin <k.shelekhin@yadro.com>
Reviewed-by: Bart van Assche <bvanassche@acm.org>
Signed-off-by: Viacheslav Dubeyko <v.dubeiko@yadro.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>