iscsi: Validate DataSN values in Data-In PDUs in the initiator.

[jhb]

Summary

As is done in the target, require that DataSN values are consecutive
and in-order. If an out of order Data-In PDU is received, force a
session reconnect. In addition, when a SCSI Response PDU is received,
verify that the ExpDataSN field matches the count of Data-In PDUs
received for this command. If not, fail the I/O request.

Sponsored by: Chelsio Communications

[mav]

Generally it looks good to me. I am just thinking whether in case of bhssr_expdatasn mismatch we should also kill the connection, since it should not happen.

[jhb]

In D31594#712266, @mav wrote:

Generally it looks good to me. I am just thinking whether in case of bhssr_expdatasn mismatch we should also kill the connection, since it should not happen.

Mmmm, quite possibly, I just wasn't sure how to do it here.

[jhb]

sys/dev/iscsi/iscsi.c

945

If I force a reconnect and skip the call to xpt_done() at the end of the function, will the ccb get resubmitted after the connection has reconnected?

[mav]

sys/dev/iscsi/iscsi.c

945

As I see, iscsi_session_terminate_tasks() completes with CAM_REQUEUE_REQ only I/Os in is_outstanding queue. So for that to happen this check and connection termination should be done before iscsi_outstanding_remove() above.

[jhb]

• Reconnect if expdatasn doesn't match.

[jhb]

• Trim a no-longer-needed variable.

[mav]

sys/dev/iscsi/iscsi.c

897

Wouldn't it be better to say "SCSI Response" as the PDU is called in RFC?

[jhb]

• Update error message.