[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>

39 files changed, 12178 insertions, 0 deletions

diff --git a/fs/Kconfig b/fs/Kconfig
index bec8afa5704..3a32f3f97e9 100644
--- a/fs/Kconfig
+++ b/fs/Kconfig
@@ -1831,6 +1831,7 @@ source "fs/partitions/Kconfig"
 endmenu
 
 source "fs/nls/Kconfig"
+source "fs/dlm/Kconfig"
 
 endmenu
 
diff --git a/fs/Makefile b/fs/Makefile
index 0922727732c..b298f4fdc6f 100644
--- a/fs/Makefile
+++ b/fs/Makefile
@@ -48,6 +48,7 @@ obj-$(CONFIG_SYSFS)		+= sysfs/
 obj-y				+= devpts/
 
 obj-$(CONFIG_PROFILING)		+= dcookies.o
+obj-$(CONFIG_DLM)		+= dlm/
  
 # Do not add any filesystems before this line
 obj-$(CONFIG_REISERFS_FS)	+= reiserfs/
diff --git a/fs/dlm/Kconfig b/fs/dlm/Kconfig
new file mode 100644
index 00000000000..d01f735e6e0
--- /dev/null
+++ b/fs/dlm/Kconfig
@@ -0,0 +1,30 @@
+menu "Distributed Lock Manager"
+	depends on INET && EXPERIMENTAL
+
+config DLM
+	tristate "Distributed Lock Manager (DLM)"
+	depends on SYSFS
+	depends on IPV6 || IPV6=n
+	select IP_SCTP
+	select CONFIGFS_FS
+	help
+	A general purpose distributed lock manager for kernel or userspace
+	applications.
+
+config DLM_DEVICE
+	tristate "DLM device for userspace access"
+	depends on DLM
+	help
+	This module creates a misc device through which the dlm lockspace
+	and locking functions become available to userspace applications
+	(usually through the libdlm library).
+
+config DLM_DEBUG
+	bool "DLM debugging"
+	depends on DLM
+	help
+	Under the debugfs mount point, the name of each lockspace will
+	appear as a file in the "dlm" directory.  The output is the
+	list of resource and locks the local node knows about.
+
+endmenu
diff --git a/fs/dlm/Makefile b/fs/dlm/Makefile
new file mode 100644
index 00000000000..1e6232e7d8e
--- /dev/null
+++ b/fs/dlm/Makefile
@@ -0,0 +1,21 @@
+obj-$(CONFIG_DLM) +=		dlm.o
+obj-$(CONFIG_DLM_DEVICE) +=	dlm_device.o
+
+dlm-y :=			ast.o \
+				config.o \
+				dir.o \
+				lock.o \
+				lockspace.o \
+				lowcomms.o \
+				main.o \
+				member.o \
+				memory.o \
+				midcomms.o \
+				rcom.o \
+				recover.o \
+				recoverd.o \
+				requestqueue.o \
+				util.o
+dlm-$(CONFIG_DLM_DEBUG) +=	debug_fs.o
+
+dlm_device-y :=			device.o
diff --git a/fs/dlm/ast.c b/fs/dlm/ast.c
new file mode 100644
index 00000000000..2bd1c5e1a72
--- /dev/null
+++ b/fs/dlm/ast.c
@@ -0,0 +1,167 @@
+/******************************************************************************
+*******************************************************************************
+**
+**  Copyright (C) Sistina Software, Inc.  1997-2003  All rights reserved.
+**  Copyright (C) 2004-2005 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 "lock.h"
+#include "ast.h"
+
+#define WAKE_ASTS  0
+
+static struct list_head		ast_queue;
+static spinlock_t		ast_queue_lock;
+static struct task_struct *	astd_task;
+static unsigned long		astd_wakeflags;
+static struct semaphore		astd_running;
+
+
+void dlm_del_ast(struct dlm_lkb *lkb)
+{
+	spin_lock(&ast_queue_lock);
+	if (lkb->lkb_ast_type & (AST_COMP | AST_BAST))
+		list_del(&lkb->lkb_astqueue);
+	spin_unlock(&ast_queue_lock);
+}
+
+void dlm_add_ast(struct dlm_lkb *lkb, int type)
+{
+	spin_lock(&ast_queue_lock);
+	if (!(lkb->lkb_ast_type & (AST_COMP | AST_BAST))) {
+		kref_get(&lkb->lkb_ref);
+		list_add_tail(&lkb->lkb_astqueue, &ast_queue);
+	}
+	lkb->lkb_ast_type |= type;
+	spin_unlock(&ast_queue_lock);
+
+	set_bit(WAKE_ASTS, &astd_wakeflags);
+	wake_up_process(astd_task);
+}
+
+static void process_asts(void)
+{
+	struct dlm_ls *ls = NULL;
+	struct dlm_rsb *r = NULL;
+	struct dlm_lkb *lkb;
+	void (*cast) (long param);
+	void (*bast) (long param, int mode);
+	int type = 0, found, bmode;
+
+	for (;;) {
+		found = FALSE;
+		spin_lock(&ast_queue_lock);
+		list_for_each_entry(lkb, &ast_queue, lkb_astqueue) {
+			r = lkb->lkb_resource;
+			ls = r->res_ls;
+
+			if (dlm_locking_stopped(ls))
+				continue;
+
+			list_del(&lkb->lkb_astqueue);
+			type = lkb->lkb_ast_type;
+			lkb->lkb_ast_type = 0;
+			found = TRUE;
+			break;
+		}
+		spin_unlock(&ast_queue_lock);
+
+		if (!found)
+			break;
+
+		cast = lkb->lkb_astaddr;
+		bast = lkb->lkb_bastaddr;
+		bmode = lkb->lkb_bastmode;
+
+		if ((type & AST_COMP) && cast)
+			cast(lkb->lkb_astparam);
+
+		/* FIXME: Is it safe to look at lkb_grmode here
+		   without doing a lock_rsb() ?
+		   Look at other checks in v1 to avoid basts. */
+
+		if ((type & AST_BAST) && bast)
+			if (!dlm_modes_compat(lkb->lkb_grmode, bmode))
+				bast(lkb->lkb_astparam, bmode);
+
+		/* this removes the reference added by dlm_add_ast
+		   and may result in the lkb being freed */
+		dlm_put_lkb(lkb);
+
+		schedule();
+	}
+}
+
+static inline int no_asts(void)
+{
+	int ret;
+
+	spin_lock(&ast_queue_lock);
+	ret = list_empty(&ast_queue);
+	spin_unlock(&ast_queue_lock);
+	return ret;
+}
+
+static int dlm_astd(void *data)
+{
+	while (!kthread_should_stop()) {
+		set_current_state(TASK_INTERRUPTIBLE);
+		if (!test_bit(WAKE_ASTS, &astd_wakeflags))
+			schedule();
+		set_current_state(TASK_RUNNING);
+
+		down(&astd_running);
+		if (test_and_clear_bit(WAKE_ASTS, &astd_wakeflags))
+			process_asts();
+		up(&astd_running);
+	}
+	return 0;
+}
+
+void dlm_astd_wake(void)
+{
+	if (!no_asts()) {
+		set_bit(WAKE_ASTS, &astd_wakeflags);
+		wake_up_process(astd_task);
+	}
+}
+
+int dlm_astd_start(void)
+{
+	struct task_struct *p;
+	int error = 0;
+
+	INIT_LIST_HEAD(&ast_queue);
+	spin_lock_init(&ast_queue_lock);
+	init_MUTEX(&astd_running);
+
+	p = kthread_run(dlm_astd, NULL, "dlm_astd");
+	if (IS_ERR(p))
+		error = PTR_ERR(p);
+	else
+		astd_task = p;
+	return error;
+}
+
+void dlm_astd_stop(void)
+{
+	kthread_stop(astd_task);
+}
+
+void dlm_astd_suspend(void)
+{
+	down(&astd_running);
+}
+
+void dlm_astd_resume(void)
+{
+	up(&astd_running);
+}
+
diff --git a/fs/dlm/ast.h b/fs/dlm/ast.h
new file mode 100644
index 00000000000..6ee276c74c5
--- /dev/null
+++ b/fs/dlm/ast.h
@@ -0,0 +1,26 @@
+/******************************************************************************
+*******************************************************************************
+**
+**  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.
+**
+*******************************************************************************
+******************************************************************************/
+
+#ifndef __ASTD_DOT_H__
+#define __ASTD_DOT_H__
+
+void dlm_add_ast(struct dlm_lkb *lkb, int type);
+void dlm_del_ast(struct dlm_lkb *lkb);
+
+void dlm_astd_wake(void);
+int dlm_astd_start(void);
+void dlm_astd_stop(void);
+void dlm_astd_suspend(void);
+void dlm_astd_resume(void);
+
+#endif
+
diff --git a/fs/dlm/config.c b/fs/dlm/config.c
new file mode 100644
index 00000000000..024ace9973a
--- /dev/null
+++ b/fs/dlm/config.c
@@ -0,0 +1,787 @@
+/******************************************************************************
+*******************************************************************************
+**
+**  Copyright (C) Sistina Software, Inc.  1997-2003  All rights reserved.
+**  Copyright (C) 2004-2005 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 <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/configfs.h>
+#include <net/sock.h>
+
+#include "config.h"
+
+/*
+ * /config/dlm/<cluster>/spaces/<space>/nodes/<node>/nodeid
+ * /config/dlm/<cluster>/spaces/<space>/nodes/<node>/weight
+ * /config/dlm/<cluster>/comms/<comm>/nodeid
+ * /config/dlm/<cluster>/comms/<comm>/local
+ * /config/dlm/<cluster>/comms/<comm>/addr
+ * The <cluster> level is useless, but I haven't figured out how to avoid it.
+ */
+
+static struct config_group *space_list;
+static struct config_group *comm_list;
+static struct comm *local_comm;
+
+struct clusters;
+struct cluster;
+struct spaces;
+struct space;
+struct comms;
+struct comm;
+struct nodes;
+struct node;
+
+static struct config_group *make_cluster(struct config_group *, const char *);
+static void drop_cluster(struct config_group *, struct config_item *);
+static void release_cluster(struct config_item *);
+static struct config_group *make_space(struct config_group *, const char *);
+static void drop_space(struct config_group *, struct config_item *);
+static void release_space(struct config_item *);
+static struct config_item *make_comm(struct config_group *, const char *);
+static void drop_comm(struct config_group *, struct config_item *);
+static void release_comm(struct config_item *);
+static struct config_item *make_node(struct config_group *, const char *);
+static void drop_node(struct config_group *, struct config_item *);
+static void release_node(struct config_item *);
+
+static ssize_t show_comm(struct config_item *i, struct configfs_attribute *a,
+			 char *buf);
+static ssize_t store_comm(struct config_item *i, struct configfs_attribute *a,
+			  const char *buf, size_t len);
+static ssize_t show_node(struct config_item *i, struct configfs_attribute *a,
+			 char *buf);
+static ssize_t store_node(struct config_item *i, struct configfs_attribute *a,
+			  const char *buf, size_t len);
+
+static ssize_t comm_nodeid_read(struct comm *cm, char *buf);
+static ssize_t comm_nodeid_write(struct comm *cm, const char *buf, size_t len);
+static ssize_t comm_local_read(struct comm *cm, char *buf);
+static ssize_t comm_local_write(struct comm *cm, const char *buf, size_t len);
+static ssize_t comm_addr_write(struct comm *cm, const char *buf, size_t len);
+static ssize_t node_nodeid_read(struct node *nd, char *buf);
+static ssize_t node_nodeid_write(struct node *nd, const char *buf, size_t len);
+static ssize_t node_weight_read(struct node *nd, char *buf);
+static ssize_t node_weight_write(struct node *nd, const char *buf, size_t len);
+
+enum {
+	COMM_ATTR_NODEID = 0,
+	COMM_ATTR_LOCAL,
+	COMM_ATTR_ADDR,
+};
+
+struct comm_attribute {
+	struct configfs_attribute attr;
+	ssize_t (*show)(struct comm *, char *);
+	ssize_t (*store)(struct comm *, const char *, size_t);
+};
+
+static struct comm_attribute comm_attr_nodeid = {
+	.attr   = { .ca_owner = THIS_MODULE,
+                    .ca_name = "nodeid",
+                    .ca_mode = S_IRUGO | S_IWUSR },
+	.show   = comm_nodeid_read,
+	.store  = comm_nodeid_write,
+};
+
+static struct comm_attribute comm_attr_local = {
+	.attr   = { .ca_owner = THIS_MODULE,
+                    .ca_name = "local",
+                    .ca_mode = S_IRUGO | S_IWUSR },
+	.show   = comm_local_read,
+	.store  = comm_local_write,
+};
+
+static struct comm_attribute comm_attr_addr = {
+	.attr   = { .ca_owner = THIS_MODULE,
+                    .ca_name = "addr",
+                    .ca_mode = S_IRUGO | S_IWUSR },
+	.store  = comm_addr_write,
+};
+
+static struct configfs_attribute *comm_attrs[] = {
+	[COMM_ATTR_NODEID] = &comm_attr_nodeid.attr,
+	[COMM_ATTR_LOCAL] = &comm_attr_local.attr,
+	[COMM_ATTR_ADDR] = &comm_attr_addr.attr,
+	NULL,
+};
+
+enum {
+	NODE_ATTR_NODEID = 0,
+	NODE_ATTR_WEIGHT,
+};
+
+struct node_attribute {
+	struct configfs_attribute attr;
+	ssize_t (*show)(struct node *, char *);
+	ssize_t (*store)(struct node *, const char *, size_t);
+};
+
+static struct node_attribute node_attr_nodeid = {
+	.attr   = { .ca_owner = THIS_MODULE,
+                    .ca_name = "nodeid",
+                    .ca_mode = S_IRUGO | S_IWUSR },
+	.show   = node_nodeid_read,
+	.store  = node_nodeid_write,
+};
+
+static struct node_attribute node_attr_weight = {
+	.attr   = { .ca_owner = THIS_MODULE,
+                    .ca_name = "weight",
+                    .ca_mode = S_IRUGO | S_IWUSR },
+	.show   = node_weight_read,
+	.store  = node_weight_write,
+};
+
+static struct configfs_attribute *node_attrs[] = {
+	[NODE_ATTR_NODEID] = &node_attr_nodeid.attr,
+	[NODE_ATTR_WEIGHT] = &node_attr_weight.attr,
+	NULL,
+};
+
+struct clusters {
+	struct configfs_subsystem subsys;
+};
+
+struct cluster {
+	struct config_group group;
+};
+
+struct spaces {
+	struct config_group ss_group;
+};
+
+struct space {
+	struct config_group group;
+	struct list_head members;
+	struct semaphore members_lock;
+	int members_count;
+};
+
+struct comms {
+	struct config_group cs_group;
+};
+
+struct comm {
+	struct config_item item;
+	int nodeid;
+	int local;
+	int addr_count;
+	struct sockaddr_storage *addr[DLM_MAX_ADDR_COUNT];
+};
+
+struct nodes {
+	struct config_group ns_group;
+};
+
+struct node {
+	struct config_item item;
+	struct list_head list; /* space->members */
+	int nodeid;
+	int weight;
+};
+
+static struct configfs_group_operations clusters_ops = {
+	.make_group = make_cluster,
+	.drop_item = drop_cluster,
+};
+
+static struct configfs_item_operations cluster_ops = {
+	.release = release_cluster,
+};
+
+static struct configfs_group_operations spaces_ops = {
+	.make_group = make_space,
+	.drop_item = drop_space,
+};
+
+static struct configfs_item_operations space_ops = {
+	.release = release_space,
+};
+
+static struct configfs_group_operations comms_ops = {
+	.make_item = make_comm,
+	.drop_item = drop_comm,
+};
+
+static struct configfs_item_operations comm_ops = {
+	.release = release_comm,
+	.show_attribute = show_comm,
+	.store_attribute = store_comm,
+};
+
+static struct configfs_group_operations nodes_ops = {
+	.make_item = make_node,
+	.drop_item = drop_node,
+};
+
+static struct configfs_item_operations node_ops = {
+	.release = release_node,
+	.show_attribute = show_node,
+	.store_attribute = store_node,
+};
+
+static struct config_item_type clusters_type = {
+	.ct_group_ops = &clusters_ops,
+	.ct_owner = THIS_MODULE,
+};
+
+static struct config_item_type cluster_type = {
+	.ct_item_ops = &cluster_ops,
+	.ct_owner = THIS_MODULE,
+};
+
+static struct config_item_type spaces_type = {
+	.ct_group_ops = &spaces_ops,
+	.ct_owner = THIS_MODULE,
+};
+
+static struct config_item_type space_type = {
+	.ct_item_ops = &space_ops,
+	.ct_owner = THIS_MODULE,
+};
+
+static struct config_item_type comms_type = {
+	.ct_group_ops = &comms_ops,
+	.ct_owner = THIS_MODULE,
+};
+
+static struct config_item_type comm_type = {
+	.ct_item_ops = &comm_ops,
+	.ct_attrs = comm_attrs,
+	.ct_owner = THIS_MODULE,
+};
+
+static struct config_item_type nodes_type = {
+	.ct_group_ops = &nodes_ops,
+	.ct_owner = THIS_MODULE,
+};
+
+static struct config_item_type node_type = {
+	.ct_item_ops = &node_ops,
+	.ct_attrs = node_attrs,
+	.ct_owner = THIS_MODULE,
+};
+
+static struct cluster *to_cluster(struct config_item *i)
+{
+	return i ? container_of(to_config_group(i), struct cluster, group):NULL;
+}
+
+static struct space *to_space(struct config_item *i)
+{
+	return i ? container_of(to_config_group(i), struct space, group) : NULL;
+}
+
+static struct comm *to_comm(struct config_item *i)
+{
+	return i ? container_of(i, struct comm, item) : NULL;
+}
+
+static struct node *to_node(struct config_item *i)
+{
+	return i ? container_of(i, struct node, item) : NULL;
+}
+
+static struct config_group *make_cluster(struct config_group *g,
+					 const char *name)
+{
+	struct cluster *cl = NULL;
+	struct spaces *sps = NULL;
+	struct comms *cms = NULL;
+	void *gps = NULL;
+
+	cl = kzalloc(sizeof(struct cluster), GFP_KERNEL);
+	gps = kcalloc(3, sizeof(struct config_group *), GFP_KERNEL);
+	sps = kzalloc(sizeof(struct spaces), GFP_KERNEL);
+	cms = kzalloc(sizeof(struct comms), GFP_KERNEL);
+
+	if (!cl || !gps || !sps || !cms)
+		goto fail;
+
+	config_group_init_type_name(&cl->group, name, &cluster_type);
+	config_group_init_type_name(&sps->ss_group, "spaces", &spaces_type);
+	config_group_init_type_name(&cms->cs_group, "comms", &comms_type);
+
+	cl->group.default_groups = gps;
+	cl->group.default_groups[0] = &sps->ss_group;
+	cl->group.default_groups[1] = &cms->cs_group;
+	cl->group.default_groups[2] = NULL;
+
+	space_list = &sps->ss_group;
+	comm_list = &cms->cs_group;
+	return &cl->group;
+
+ fail:
+	kfree(cl);
+	kfree(gps);
+	kfree(sps);
+	kfree(cms);
+	return NULL;
+}
+
+static void drop_cluster(struct config_group *g, struct config_item *i)
+{
+	struct cluster *cl = to_cluster(i);
+	struct config_item *tmp;
+	int j;
+
+	for (j = 0; cl->group.default_groups[j]; j++) {
+		tmp = &cl->group.default_groups[j]->cg_item;
+		cl->group.default_groups[j] = NULL;
+		config_item_put(tmp);
+	}
+
+	space_list = NULL;
+	comm_list = NULL;
+
+	config_item_put(i);
+}
+
+static void release_cluster(struct config_item *i)
+{
+	struct cluster *cl = to_cluster(i);
+	kfree(cl->group.default_groups);
+	kfree(cl);
+}
+
+static struct config_group *make_space(struct config_group *g, const char *name)
+{
+	struct space *sp = NULL;
+	struct nodes *nds = NULL;
+	void *gps = NULL;
+
+	sp = kzalloc(sizeof(struct space), GFP_KERNEL);
+	gps = kcalloc(2, sizeof(struct config_group *), GFP_KERNEL);
+	nds = kzalloc(sizeof(struct nodes), GFP_KERNEL);
+
+	if (!sp || !gps || !nds)
+		goto fail;
+
+	config_group_init_type_name(&sp->group, name, &space_type);
+	config_group_init_type_name(&nds->ns_group, "nodes", &nodes_type);
+
+	sp->group.default_groups = gps;
+	sp->group.default_groups[0] = &nds->ns_group;
+	sp->group.default_groups[1] = NULL;
+
+	INIT_LIST_HEAD(&sp->members);
+	init_MUTEX(&sp->members_lock);
+	sp->members_count = 0;
+	return &sp->group;
+
+ fail:
+	kfree(sp);
+	kfree(gps);
+	kfree(nds);
+	return NULL;
+}
+
+static void drop_space(struct config_group *g, struct config_item *i)
+{
+	struct space *sp = to_space(i);
+	struct config_item *tmp;
+	int j;
+
+	/* assert list_empty(&sp->members) */
+
+	for (j = 0; sp->group.default_groups[j]; j++) {
+		tmp = &sp->group.default_groups[j]->cg_item;
+		sp->group.default_groups[j] = NULL;
+		config_item_put(tmp);
+	}
+
+	config_item_put(i);
+}
+
+static void release_space(struct config_item *i)
+{
+	struct space *sp = to_space(i);
+	kfree(sp->group.default_groups);
+	kfree(sp);
+}
+
+static struct config_item *make_comm(struct config_group *g, const char *name)
+{
+	struct comm *cm;
+
+	cm = kzalloc(sizeof(struct comm), GFP_KERNEL);
+	if (!cm)
+		return NULL;
+
+	config_item_init_type_name(&cm->item, name, &comm_type);
+	cm->nodeid = -1;
+	cm->local = 0;
+	cm->addr_count = 0;
+	return &cm->item;
+}
+
+static void drop_comm(struct config_group *g, struct config_item *i)
+{
+	struct comm *cm = to_comm(i);
+	if (local_comm == cm)
+		local_comm = NULL;
+	while (cm->addr_count--)
+		kfree(cm->addr[cm->addr_count]);
+	config_item_put(i);
+}
+
+static void release_comm(struct config_item *i)
+{
+	struct comm *cm = to_comm(i);
+	kfree(cm);
+}
+
+static struct config_item *make_node(struct config_group *g, const char *name)
+{
+	struct space *sp = to_space(g->cg_item.ci_parent);
+	struct node *nd;
+
+	nd = kzalloc(sizeof(struct node), GFP_KERNEL);
+	if (!nd)
+		return NULL;
+
+	config_item_init_type_name(&nd->item, name, &node_type);
+	nd->nodeid = -1;
+	nd->weight = 1;  /* default weight of 1 if none is set */
+
+	down(&sp->members_lock);
+	list_add(&nd->list, &sp->members);
+	sp->members_count++;
+	up(&sp->members_lock);
+
+	return &nd->item;
+}
+
+static void drop_node(struct config_group *g, struct config_item *i)
+{
+	struct space *sp = to_space(g->cg_item.ci_parent);
+	struct node *nd = to_node(i);
+
+	down(&sp->members_lock);
+	list_del(&nd->list);
+	sp->members_count--;
+	up(&sp->members_lock);
+
+	config_item_put(i);
+}
+
+static void release_node(struct config_item *i)
+{
+	struct node *nd = to_node(i);
+	kfree(nd);
+}
+
+static struct clusters clusters_root = {
+	.subsys = {
+		.su_group = {
+			.cg_item = {
+				.ci_namebuf = "dlm",
+				.ci_type = &clusters_type,
+			},
+		},
+	},
+};
+
+int dlm_config_init(void)
+{
+	config_group_init(&clusters_root.subsys.su_group);
+	init_MUTEX(&clusters_root.subsys.su_sem);
+	return configfs_register_subsystem(&clusters_root.subsys);
+}
+
+void dlm_config_exit(void)
+{
+	configfs_unregister_subsystem(&clusters_root.subsys);
+}
+
+/*
+ * Functions for user space to read/write attributes
+ */
+
+static ssize_t show_comm(struct config_item *i, struct configfs_attribute *a,
+			 char *buf)
+{
+	struct comm *cm = to_comm(i);
+	struct comm_attribute *cma =
+			container_of(a, struct comm_attribute, attr);
+	return cma->show ? cma->show(cm, buf) : 0;
+}
+
+static ssize_t store_comm(struct config_item *i, struct configfs_attribute *a,
+			  const char *buf, size_t len)
+{
+	struct comm *cm = to_comm(i);
+	struct comm_attribute *cma =
+		container_of(a, struct comm_attribute, attr);
+	return cma->store ? cma->store(cm, buf, len) : -EINVAL;
+}
+
+static ssize_t comm_nodeid_read(struct comm *cm, char *buf)
+{
+	return sprintf(buf, "%d\n", cm->nodeid);
+}
+
+static ssize_t comm_nodeid_write(struct comm *cm, const char *buf, size_t len)
+{
+	cm->nodeid = simple_strtol(buf, NULL, 0);
+	return len;
+}
+
+static ssize_t comm_local_read(struct comm *cm, char *buf)
+{
+	return sprintf(buf, "%d\n", cm->local);
+}
+
+static ssize_t comm_local_write(struct comm *cm, const char *buf, size_t len)
+{
+	cm->local= simple_strtol(buf, NULL, 0);
+	if (cm->local && !local_comm)
+		local_comm = cm;
+	return len;
+}
+
+static ssize_t comm_addr_write(struct comm *cm, const char *buf, size_t len)
+{
+	struct sockaddr_storage *addr;
+
+	if (len != sizeof(struct sockaddr_storage))
+		return -EINVAL;
+
+	if (cm->addr_count >= DLM_MAX_ADDR_COUNT)
+		return -ENOSPC;
+
+	addr = kzalloc(sizeof(*addr), GFP_KERNEL);
+	if (!addr)
+		return -ENOMEM;
+
+	memcpy(addr, buf, len);
+	cm->addr[cm->addr_count++] = addr;
+	return len;
+}
+
+static ssize_t show_node(struct config_item *i, struct configfs_attribute *a,
+			 char *buf)
+{
+	struct node *nd = to_node(i);
+	struct node_attribute *nda =
+			container_of(a, struct node_attribute, attr);
+	return nda->show ? nda->show(nd, buf) : 0;
+}
+
+static ssize_t store_node(struct config_item *i, struct configfs_attribute *a,
+			  const char *buf, size_t len)
+{
+	struct node *nd = to_node(i);
+	struct node_attribute *nda =
+		container_of(a, struct node_attribute, attr);
+	return nda->store ? nda->store(nd, buf, len) : -EINVAL;
+}
+
+static ssize_t node_nodeid_read(struct node *nd, char *buf)
+{
+	return sprintf(buf, "%d\n", nd->nodeid);
+}
+
+static ssize_t node_nodeid_write(struct node *nd, const char *buf, size_t len)
+{
+	nd->nodeid = simple_strtol(buf, NULL, 0);
+	return len;
+}
+
+static ssize_t node_weight_read(struct node *nd, char *buf)
+{</