iscsid: Check session's target_state before reopen a session

When iscsid restart and sync a session, check if session's target_state
is BOUND before reopen it. If not, this session would be shutdown.

Refer to https://lore.kernel.org/all/20220802034729.2566787-1-haowenchao@huawei.com/
for details.

Signed-off-by: Wenchao Hao <haowenchao@huawei.com>

usr/initiator.c

@@ -2034,11 +2034,40 @@ sync_conn(iscsi_session_t *session, uint32_t cid)
 	return 0;
 }
 
+static int
+iscsi_sysfs_get_target_state(uint32_t sid, char *state, int len)
+{
+	char id[NAME_SIZE];
+	int fd;
+	int ret = 0;
+
+	sprintf(id, "/sys/class/iscsi_session/session%d/target_state", sid);
+
+	fd = open(id, O_RDONLY);
+	if (fd < 0) {
+		log_warning("failed to open session's target state %s", strerror(errno));
+		return errno;
+	}
+
+	ret = read(fd, state, len);
+	if (ret < 0) {
+		log_warning("failed to read session's target state %s", strerror(errno));
+		return errno;
+	}
+
+	if (ret && state[ret - 1] == '\n')
+		state[ret - 1] = '\0';
+
+	return 0;
+}
+
 int
 iscsi_sync_session(node_rec_t *rec, queue_task_t *qtask, uint32_t sid)
 {
 	iscsi_session_t *session;
+	iscsi_conn_t *conn;
 	struct iscsi_transport *t;
+	char state[12];
 	int err;
 
 	session = session_find_by_sid(sid);
@@ -2067,8 +2096,39 @@ iscsi_sync_session(node_rec_t *rec, queue_task_t *qtask, uint32_t sid)
 		goto destroy_session;
 
 	qtask->rsp.command = MGMT_IPC_SESSION_SYNC;
-
 	log_debug(3, "Started sync iSCSI session %d", session->id);
+
+	err = iscsi_sysfs_get_target_state(sid, state, 12);
+	if (err || !strncmp(state, "BOUND", 5))
+		goto reopen_session;
+
+	/*
+	 * If get target state succeed and the state is not BOUND, it means
+	 * the session is in an invalid state which should not be reopened
+	 */
+	mgmt_ipc_write_rsp(qtask, ISCSI_SUCCESS);
+
+	/*
+	 * Update connection's state so ipc->stop_conn() would
+	 * be called for this connection in session_conn_shutdown()
+	 *
+	 * TODO: setting connection's state according to sysfs
+	 */
+	conn = &session->conn[0];
+	conn->state = ISCSI_CONN_STATE_IN_LOGIN;
+
+
+	if (!strncmp(state, "UNBINDING", 9))
+		log_warning("Donot sync UNBINDING session%d", sid);
+
+	if (!strncmp(state, "UNBOUND", 7)) {
+		log_warning("Shutdown UNBOUND session%d", sid);
+		session_conn_shutdown(conn, NULL, ISCSI_SUCCESS);
+	}
+
+	return 0;
+
+reopen_session:
 	session->notify_qtask = qtask;
 	session_conn_reopen(&session->conn[0], qtask,
 			    STOP_CONN_RECOVER);