[DLM] The core of the DLM for GFS2/CLVM

This is the core of the distributed lock manager which is required
to use GFS2 as a cluster filesystem. It is also used by CLVM and
can be used as a standalone lock manager independantly of either
of these two projects.

It implements VAX-style locking modes.

Signed-off-by: David Teigland <teigland@redhat.com>
Signed-off-by: Steve Whitehouse <swhiteho@redhat.com>

1 files changed, 184 insertions, 0 deletions

diff --git a/fs/dlm/requestqueue.c b/fs/dlm/requestqueue.c
new file mode 100644
index 000000000000..36afe99e4f93
--- /dev/null
+++ b/fs/dlm/requestqueue.c
@@ -0,0 +1,184 @@
+/******************************************************************************
+*******************************************************************************
+**
+**  Copyright (C) 2005 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
+**  of the GNU General Public License v.2.
+**
+*******************************************************************************
+******************************************************************************/
+
+#include "dlm_internal.h"
+#include "member.h"
+#include "lock.h"
+#include "dir.h"
+#include "config.h"
+#include "requestqueue.h"
+
+struct rq_entry {
+	struct list_head list;
+	int nodeid;
+	char request[1];
+};
+
+/*
+ * Requests received while the lockspace is in recovery get added to the
+ * request queue and processed when recovery is complete.  This happens when
+ * the lockspace is suspended on some nodes before it is on others, or the
+ * lockspace is enabled on some while still suspended on others.
+ */
+
+void dlm_add_requestqueue(struct dlm_ls *ls, int nodeid, struct dlm_header *hd)
+{
+	struct rq_entry *e;
+	int length = hd->h_length;
+
+	if (dlm_is_removed(ls, nodeid))
+		return;
+
+	e = kmalloc(sizeof(struct rq_entry) + length, GFP_KERNEL);
+	if (!e) {
+		log_print("dlm_add_requestqueue: out of memory\n");
+		return;
+	}
+
+	e->nodeid = nodeid;
+	memcpy(e->request, hd, length);
+
+	down(&ls->ls_requestqueue_lock);
+	list_add_tail(&e->list, &ls->ls_requestqueue);
+	up(&ls->ls_requestqueue_lock);
+}
+
+int dlm_process_requestqueue(struct dlm_ls *ls)
+{
+	struct rq_entry *e;
+	struct dlm_header *hd;
+	int error = 0;
+
+	down(&ls->ls_requestqueue_lock);
+
+	for (;;) {
+		if (list_empty(&ls->ls_requestqueue)) {
+			up(&ls->ls_requestqueue_lock);
+			error = 0;
+			break;
+		}
+		e = list_entry(ls->ls_requestqueue.next, struct rq_entry, list);
+		up(&ls->ls_requestqueue_lock);
+
+		hd = (struct dlm_header *) e->request;
+		error = dlm_receive_message(hd, e->nodeid, TRUE);
+
+		if (error == -EINTR) {
+			/* entry is left on requestqueue */
+			log_debug(ls, "process_requestqueue abort eintr");
+			break;
+		}
+
+		down(&ls->ls_requestqueue_lock);
+		list_del(&e->list);
+		kfree(e);
+
+		if (dlm_locking_stopped(ls)) {
+			log_debug(ls, "process_requestqueue abort running");
+			up(&ls->ls_requestqueue_lock);
+			error = -EINTR;
+			break;
+		}
+		schedule();
+	}
+
+	return error;
+}
+
+/*
+ * After recovery is done, locking is resumed and dlm_recoverd takes all the
+ * saved requests and processes them as they would have been by dlm_recvd.  At
+ * the same time, dlm_recvd will start receiving new requests from remote
+ * nodes.  We want to delay dlm_recvd processing new requests until
+ * dlm_recoverd has finished processing the old saved requests.
+ */
+
+void dlm_wait_requestqueue(struct dlm_ls *ls)
+{
+	for (;;) {
+		down(&ls->ls_requestqueue_lock);
+		if (list_empty(&ls->ls_requestqueue))
+			break;
+		if (dlm_locking_stopped(ls))
+			break;
+		up(&ls->ls_requestqueue_lock);
+		schedule();
+	}
+	up(&ls->ls_requestqueue_lock);
+}
+
+static int purge_request(struct dlm_ls *ls, struct dlm_message *ms, int nodeid)
+{
+	uint32_t type = ms->m_type;
+
+	if (dlm_is_removed(ls, nodeid))
+		return 1;
+
+	/* directory operations are always purged because the directory is
+	   always rebuilt during recovery and the lookups resent */
+
+	if (type == DLM_MSG_REMOVE ||
+	    type == DLM_MSG_LOOKUP ||
+	    type == DLM_MSG_LOOKUP_REPLY)
+		return 1;
+
+	if (!dlm_no_directory(ls))
+		return 0;
+
+	/* with no directory, the master is likely to change as a part of
+	   recovery; requests to/from the defunct master need to be purged */
+
+	switch (type) {
+	case DLM_MSG_REQUEST:
+	case DLM_MSG_CONVERT:
+	case DLM_MSG_UNLOCK:
+	case DLM_MSG_CANCEL:
+		/* we're no longer the master of this resource, the sender
+		   will resend to the new master (see waiter_needs_recovery) */
+
+		if (dlm_hash2nodeid(ls, ms->m_hash) != dlm_our_nodeid())
+			return 1;
+		break;
+
+	case DLM_MSG_REQUEST_REPLY:
+	case DLM_MSG_CONVERT_REPLY:
+	case DLM_MSG_UNLOCK_REPLY:
+	case DLM_MSG_CANCEL_REPLY:
+	case DLM_MSG_GRANT:
+		/* this reply is from the former master of the resource,
+		   we'll resend to the new master if needed */
+
+		if (dlm_hash2nodeid(ls, ms->m_hash) != nodeid)
+			return 1;
+		break;
+	}
+
+	return 0;
+}
+
+void dlm_purge_requestqueue(struct dlm_ls *ls)
+{
+	struct dlm_message *ms;
+	struct rq_entry *e, *safe;
+
+	down(&ls->ls_requestqueue_lock);
+	list_for_each_entry_safe(e, safe, &ls->ls_requestqueue, list) {
+		ms = (struct dlm_message *) e->request;
+
+		if (purge_request(ls, ms, e->nodeid)) {
+			list_del(&e->list);
+			kfree(e);
+		}
+	}
+	up(&ls->ls_requestqueue_lock);
+}
+