[SCSI] libiscsi: add more informative failure message during iscsi scsi eh

This adds a more informative error code and message
for the iscsi scsi eh session drop paths. This allows
you to distinguish if the session was dropped due to
a connection failure vs the iscsi layer dropping
the session due to scsi eh failure processing.

Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>

drivers/scsi/libiscsi.c

@@ -1796,9 +1796,9 @@ static int iscsi_exec_task_mgmt_fn(struct iscsi_conn *conn,
 				      NULL, 0);
 	if (!task) {
 		spin_unlock_bh(&session->lock);
+		iscsi_conn_printk(KERN_ERR, conn, "Could not send TMF.\n");
 		iscsi_conn_failure(conn, ISCSI_ERR_CONN_FAILED);
 		spin_lock_bh(&session->lock);
-		ISCSI_DBG_EH(session, "tmf exec failure\n");
 		return -EPERM;
 	}
 	conn->tmfcmd_pdus_cnt++;
@@ -2203,7 +2203,7 @@ int iscsi_eh_abort(struct scsi_cmnd *sc)
 		goto success_unlocked;
 	case TMF_TIMEDOUT:
 		spin_unlock_bh(&session->lock);
-		iscsi_conn_failure(conn, ISCSI_ERR_CONN_FAILED);
+		iscsi_conn_failure(conn, ISCSI_ERR_SCSI_EH_SESSION_RST);
 		goto failed_unlocked;
 	case TMF_NOT_FOUND:
 		if (!sc->SCp.ptr) {
@@ -2290,7 +2290,7 @@ int iscsi_eh_device_reset(struct scsi_cmnd *sc)
 		break;
 	case TMF_TIMEDOUT:
 		spin_unlock_bh(&session->lock);
-		iscsi_conn_failure(conn, ISCSI_ERR_CONN_FAILED);
+		iscsi_conn_failure(conn, ISCSI_ERR_SCSI_EH_SESSION_RST);
 		goto done;
 	default:
 		conn->tmf_state = TMF_INITIAL;
@@ -2371,7 +2371,7 @@ failed:
 	 * we drop the lock here but the leadconn cannot be destoyed while
 	 * we are in the scsi eh
 	 */
-	iscsi_conn_failure(conn, ISCSI_ERR_CONN_FAILED);
+	iscsi_conn_failure(conn, ISCSI_ERR_SCSI_EH_SESSION_RST);
 
 	ISCSI_DBG_EH(session, "wait for relogin\n");
 	wait_event_interruptible(conn->ehwait,
@@ -2453,7 +2453,7 @@ int iscsi_eh_target_reset(struct scsi_cmnd *sc)
 		break;
 	case TMF_TIMEDOUT:
 		spin_unlock_bh(&session->lock);
-		iscsi_conn_failure(conn, ISCSI_ERR_CONN_FAILED);
+		iscsi_conn_failure(conn, ISCSI_ERR_SCSI_EH_SESSION_RST);
 		goto done;
 	default:
 		conn->tmf_state = TMF_INITIAL;

include/scsi/iscsi_if.h

@@ -263,6 +263,7 @@ enum iscsi_err {
 	ISCSI_ERR_INVALID_HOST		= ISCSI_ERR_BASE + 18,
 	ISCSI_ERR_XMIT_FAILED		= ISCSI_ERR_BASE + 19,
 	ISCSI_ERR_TCP_CONN_CLOSE	= ISCSI_ERR_BASE + 20,
+	ISCSI_ERR_SCSI_EH_SESSION_RST	= ISCSI_ERR_BASE + 21,
 };
 
 /*