[DLM] block dlm_recv in recovery transition
Introduce a per-lockspace rwsem that's held in read mode by dlm_recv
threads while working in the dlm. This allows dlm_recv activity to be
suspended when the lockspace transitions to, from and between recovery
cycles.
The specific bug prompting this change is one where an in-progress
recovery cycle is aborted by a new recovery cycle. While dlm_recv was
processing a recovery message, the recovery cycle was aborted and
dlm_recoverd began cleaning up. dlm_recv decremented recover_locks_count
on an rsb after dlm_recoverd had reset it to zero. This is fixed by
suspending dlm_recv (taking write lock on the rwsem) before aborting the
current recovery.
The transitions to/from normal and recovery modes are simplified by using
this new ability to block dlm_recv. The switch from normal to recovery
mode means dlm_recv goes from processing locking messages, to saving them
for later, and vice versa. Races are avoided by blocking dlm_recv when
setting the flag that switches between modes.
Signed-off-by: David Teigland <teigland@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
diff --git a/fs/dlm/midcomms.c b/fs/dlm/midcomms.c
index a5126e0..f8c69dd 100644
--- a/fs/dlm/midcomms.c
+++ b/fs/dlm/midcomms.c
@@ -2,7 +2,7 @@
*******************************************************************************
**
** Copyright (C) Sistina Software, Inc. 1997-2003 All rights reserved.
-** Copyright (C) 2004-2005 Red Hat, Inc. All rights reserved.
+** Copyright (C) 2004-2007 Red Hat, Inc. All rights reserved.
**
** This copyrighted material is made available to anyone wishing to use,
** modify, copy, or redistribute it subject to the terms and conditions
@@ -27,7 +27,6 @@
#include "dlm_internal.h"
#include "lowcomms.h"
#include "config.h"
-#include "rcom.h"
#include "lock.h"
#include "midcomms.h"
@@ -117,19 +116,7 @@
offset &= (limit - 1);
len -= msglen;
- switch (msg->h_cmd) {
- case DLM_MSG:
- dlm_receive_message(msg, nodeid, 0);
- break;
-
- case DLM_RCOM:
- dlm_receive_rcom(msg, nodeid);
- break;
-
- default:
- log_print("unknown msg type %x from %u: %u %u %u %u",
- msg->h_cmd, nodeid, msglen, len, offset, ret);
- }
+ dlm_receive_buffer(msg, nodeid);
}
if (msg != (struct dlm_header *) __tmp)