[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 <[email protected]>
Signed-off-by: Steve Whitehouse <[email protected]>

fs/Kconfig

@@ -1831,6 +1831,7 @@ source "fs/partitions/Kconfig"
 endmenu
 
 source "fs/nls/Kconfig"
+source "fs/dlm/Kconfig"
 
 endmenu
 

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/

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

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

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);
+}
+

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
+