scsi: iscsi: Report connection state in sysfs

If an iSCSI connection happens to fail while the daemon isn't running (due
to a crash or for another reason), the kernel failure report is not
received.  When the daemon restarts, there is insufficient kernel state in
sysfs for it to know that this happened.  open-iscsi tries to reopen every
connection, but on different initiators, we'd like to know which
connections have failed.

There is session->state, but that has a different lifetime than an iSCSI
connection, so it doesn't directly reflect the connection state.

[mkp: typos]

Link: https://lore.kernel.org/r/20200317233422.532961-1-krisman@collabora.com
Cc: Khazhismel Kumykov <khazhy@google.com>
Suggested-by: Junho Ryu <jayr@google.com>
Reviewed-by: Lee Duncan <lduncan@suse.com>
Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/libiscsi.c

@@ -3153,13 +3153,18 @@ void iscsi_conn_stop(struct iscsi_cls_conn *cls_conn, int flag)
 
 	switch (flag) {
 	case STOP_CONN_RECOVER:
+		cls_conn->state = ISCSI_CONN_FAILED;
+		break;
 	case STOP_CONN_TERM:
-		iscsi_start_session_recovery(session, conn, flag);
+		cls_conn->state = ISCSI_CONN_DOWN;
 		break;
 	default:
 		iscsi_conn_printk(KERN_ERR, conn,
 				  "invalid stop flag %d\n", flag);
+		return;
 	}
+
+	iscsi_start_session_recovery(session, conn, flag);
 }
 EXPORT_SYMBOL_GPL(iscsi_conn_stop);
 

drivers/scsi/scsi_transport_iscsi.c

@@ -2276,6 +2276,7 @@ iscsi_create_conn(struct iscsi_cls_session *session, int dd_size, uint32_t cid)
 	INIT_LIST_HEAD(&conn->conn_list_err);
 	conn->transport = transport;
 	conn->cid = cid;
+	conn->state = ISCSI_CONN_DOWN;
 
 	/* this is released in the dev's release function */
 	if (!get_device(&session->dev))
@@ -3709,8 +3710,11 @@ iscsi_if_recv_msg(struct sk_buff *skb, struct nlmsghdr *nlh, uint32_t *group)
 		break;
 	case ISCSI_UEVENT_START_CONN:
 		conn = iscsi_conn_lookup(ev->u.start_conn.sid, ev->u.start_conn.cid);
-		if (conn)
+		if (conn) {
 			ev->r.retcode = transport->start_conn(conn);
+			if (!ev->r.retcode)
+				conn->state = ISCSI_CONN_UP;
+		}
 		else
 			err = -EINVAL;
 		break;
@@ -3907,6 +3911,26 @@ iscsi_conn_attr(tcp_xmit_wsf, ISCSI_PARAM_TCP_XMIT_WSF);
 iscsi_conn_attr(tcp_recv_wsf, ISCSI_PARAM_TCP_RECV_WSF);
 iscsi_conn_attr(local_ipaddr, ISCSI_PARAM_LOCAL_IPADDR);
 
+static const char *const connection_state_names[] = {
+	[ISCSI_CONN_UP] = "up",
+	[ISCSI_CONN_DOWN] = "down",
+	[ISCSI_CONN_FAILED] = "failed"
+};
+
+static ssize_t show_conn_state(struct device *dev,
+			       struct device_attribute *attr, char *buf)
+{
+	struct iscsi_cls_conn *conn = iscsi_dev_to_conn(dev->parent);
+	const char *state = "unknown";
+
+	if (conn->state >= 0 &&
+	    conn->state < ARRAY_SIZE(connection_state_names))
+		state = connection_state_names[conn->state];
+
+	return sprintf(buf, "%s\n", state);
+}
+static ISCSI_CLASS_ATTR(conn, state, S_IRUGO, show_conn_state,
+			NULL);
 
 #define iscsi_conn_ep_attr_show(param)					\
 static ssize_t show_conn_ep_param_##param(struct device *dev,		\
@@ -3976,6 +4000,7 @@ static struct attribute *iscsi_conn_attrs[] = {
 	&dev_attr_conn_tcp_xmit_wsf.attr,
 	&dev_attr_conn_tcp_recv_wsf.attr,
 	&dev_attr_conn_local_ipaddr.attr,
+	&dev_attr_conn_state.attr,
 	NULL,
 };
 
@@ -4047,6 +4072,8 @@ static umode_t iscsi_conn_attr_is_visible(struct kobject *kobj,
 		param = ISCSI_PARAM_TCP_RECV_WSF;
 	else if (attr == &dev_attr_conn_local_ipaddr.attr)
 		param = ISCSI_PARAM_LOCAL_IPADDR;
+	else if (attr == &dev_attr_conn_state.attr)
+		return S_IRUGO;
 	else {
 		WARN_ONCE(1, "Invalid conn attr");
 		return 0;

include/scsi/scsi_transport_iscsi.h

@@ -188,6 +188,13 @@ extern void iscsi_ping_comp_event(uint32_t host_no,
 				  uint32_t status, uint32_t pid,
 				  uint32_t data_size, uint8_t *data);
 
+/* iscsi class connection state */
+enum iscsi_connection_state {
+	ISCSI_CONN_UP = 0,
+	ISCSI_CONN_DOWN,
+	ISCSI_CONN_FAILED,
+};
+
 struct iscsi_cls_conn {
 	struct list_head conn_list;	/* item in connlist */
 	struct list_head conn_list_err;	/* item in connlist_err */
@@ -198,6 +205,7 @@ struct iscsi_cls_conn {
 	struct iscsi_endpoint *ep;
 
 	struct device dev;		/* sysfs transport/container device */
+	enum iscsi_connection_state state;
 };
 
 #define iscsi_dev_to_conn(_dev) \