dlm: check required context while close

This patch adds a WARN_ON() check to validate the right context while
dlm_midcomms_close() is called. Even before commit 489d8e55
("fs: dlm: add reliable connection if reconnect") in this context
dlm_lowcomms_close() flushes all ongoing transmission triggered by dlm
application stack. If we do that, it's required that no new message will
be triggered by the dlm application stack. The function
dlm_midcomms_close() is not called often so we can check if all
lockspaces are in such context.
Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>

fs/dlm/lockspace.c

@@ -922,3 +922,15 @@ void dlm_stop_lockspaces(void)
 		log_print("dlm user daemon left %d lockspaces", count);
 }
 
+void dlm_stop_lockspaces_check(void)
+{
+	struct dlm_ls *ls;
+
+	spin_lock(&lslist_lock);
+	list_for_each_entry(ls, &lslist, ls_list) {
+		if (WARN_ON(!rwsem_is_locked(&ls->ls_in_recovery) ||
+			    !dlm_locking_stopped(ls)))
+			break;
+	}
+	spin_unlock(&lslist_lock);
+}

fs/dlm/lockspace.h

@@ -19,6 +19,7 @@ struct dlm_ls *dlm_find_lockspace_local(void *id);
 struct dlm_ls *dlm_find_lockspace_device(int minor);
 void dlm_put_lockspace(struct dlm_ls *ls);
 void dlm_stop_lockspaces(void);
+void dlm_stop_lockspaces_check(void);
 
 #endif				/* __LOCKSPACE_DOT_H__ */
 

fs/dlm/midcomms.c

@@ -135,6 +135,7 @@
 #include <net/tcp.h>
 
 #include "dlm_internal.h"
+#include "lockspace.h"
 #include "lowcomms.h"
 #include "config.h"
 #include "memory.h"
@@ -1412,6 +1413,8 @@ int dlm_midcomms_close(int nodeid)
 	if (nodeid == dlm_our_nodeid())
 		return 0;
 
+	dlm_stop_lockspaces_check();
+
 	idx = srcu_read_lock(&nodes_srcu);
 	/* Abort pending close/remove operation */
 	node = nodeid2node(nodeid, 0);