[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, 666 insertions, 0 deletions

diff --git a/fs/dlm/lockspace.c b/fs/dlm/lockspace.c
new file mode 100644
index 0000000..fee4659
--- /dev/null
+++ b/fs/dlm/lockspace.c
@@ -0,0 +1,666 @@
+/******************************************************************************
+*******************************************************************************
+**
+**  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 "lockspace.h"
+#include "member.h"
+#include "recoverd.h"
+#include "ast.h"
+#include "dir.h"
+#include "lowcomms.h"
+#include "config.h"
+#include "memory.h"
+#include "lock.h"
+
+#ifdef CONFIG_DLM_DEBUG
+int dlm_create_debug_file(struct dlm_ls *ls);
+void dlm_delete_debug_file(struct dlm_ls *ls);
+#else
+static inline int dlm_create_debug_file(struct dlm_ls *ls) { return 0; }
+static inline void dlm_delete_debug_file(struct dlm_ls *ls) { }
+#endif
+
+static int			ls_count;
+static struct semaphore		ls_lock;
+static struct list_head		lslist;
+static spinlock_t		lslist_lock;
+static struct task_struct *	scand_task;
+
+
+static ssize_t dlm_control_store(struct dlm_ls *ls, const char *buf, size_t len)
+{
+	ssize_t ret = len;
+	int n = simple_strtol(buf, NULL, 0);
+
+	switch (n) {
+	case 0:
+		dlm_ls_stop(ls);
+		break;
+	case 1:
+		dlm_ls_start(ls);
+		break;
+	default:
+		ret = -EINVAL;
+	}
+	return ret;
+}
+
+static ssize_t dlm_event_store(struct dlm_ls *ls, const char *buf, size_t len)
+{
+	ls->ls_uevent_result = simple_strtol(buf, NULL, 0);
+	set_bit(LSFL_UEVENT_WAIT, &ls->ls_flags);
+	wake_up(&ls->ls_uevent_wait);
+	return len;
+}
+
+static ssize_t dlm_id_show(struct dlm_ls *ls, char *buf)
+{
+	return sprintf(buf, "%u\n", ls->ls_global_id);
+}
+
+static ssize_t dlm_id_store(struct dlm_ls *ls, const char *buf, size_t len)
+{
+	ls->ls_global_id = simple_strtoul(buf, NULL, 0);
+	return len;
+}
+
+struct dlm_attr {
+	struct attribute attr;
+	ssize_t (*show)(struct dlm_ls *, char *);
+	ssize_t (*store)(struct dlm_ls *, const char *, size_t);
+};
+
+static struct dlm_attr dlm_attr_control = {
+	.attr  = {.name = "control", .mode = S_IWUSR},
+	.store = dlm_control_store
+};
+
+static struct dlm_attr dlm_attr_event = {
+	.attr  = {.name = "event_done", .mode = S_IWUSR},
+	.store = dlm_event_store
+};
+
+static struct dlm_attr dlm_attr_id = {
+	.attr  = {.name = "id", .mode = S_IRUGO | S_IWUSR},
+	.show  = dlm_id_show,
+	.store = dlm_id_store
+};
+
+static struct attribute *dlm_attrs[] = {
+	&dlm_attr_control.attr,
+	&dlm_attr_event.attr,
+	&dlm_attr_id.attr,
+	NULL,
+};
+
+static ssize_t dlm_attr_show(struct kobject *kobj, struct attribute *attr,
+			     char *buf)
+{
+	struct dlm_ls *ls  = container_of(kobj, struct dlm_ls, ls_kobj);
+	struct dlm_attr *a = container_of(attr, struct dlm_attr, attr);
+	return a->show ? a->show(ls, buf) : 0;
+}
+
+static ssize_t dlm_attr_store(struct kobject *kobj, struct attribute *attr,
+			      const char *buf, size_t len)
+{
+	struct dlm_ls *ls  = container_of(kobj, struct dlm_ls, ls_kobj);
+	struct dlm_attr *a = container_of(attr, struct dlm_attr, attr);
+	return a->store ? a->store(ls, buf, len) : len;
+}
+
+static struct sysfs_ops dlm_attr_ops = {
+	.show  = dlm_attr_show,
+	.store = dlm_attr_store,
+};
+
+static struct kobj_type dlm_ktype = {
+	.default_attrs = dlm_attrs,
+	.sysfs_ops     = &dlm_attr_ops,
+};
+
+static struct kset dlm_kset = {
+	.subsys = &kernel_subsys,
+	.kobj   = {.name = "dlm",},
+	.ktype  = &dlm_ktype,
+};
+
+static int kobject_setup(struct dlm_ls *ls)
+{
+	char lsname[DLM_LOCKSPACE_LEN];
+	int error;
+
+	memset(lsname, 0, DLM_LOCKSPACE_LEN);
+	snprintf(lsname, DLM_LOCKSPACE_LEN, "%s", ls->ls_name);
+
+	error = kobject_set_name(&ls->ls_kobj, "%s", lsname);
+	if (error)
+		return error;
+
+	ls->ls_kobj.kset = &dlm_kset;
+	ls->ls_kobj.ktype = &dlm_ktype;
+	return 0;
+}
+
+static int do_uevent(struct dlm_ls *ls, int in)
+{
+	int error;
+
+	if (in)
+		kobject_uevent(&ls->ls_kobj, KOBJ_ONLINE);
+	else
+		kobject_uevent(&ls->ls_kobj, KOBJ_OFFLINE);
+
+	error = wait_event_interruptible(ls->ls_uevent_wait,
+			test_and_clear_bit(LSFL_UEVENT_WAIT, &ls->ls_flags));
+	if (error)
+		goto out;
+
+	error = ls->ls_uevent_result;
+ out:
+	return error;
+}
+
+
+int dlm_lockspace_init(void)
+{
+	int error;
+
+	ls_count = 0;
+	init_MUTEX(&ls_lock);
+	INIT_LIST_HEAD(&lslist);
+	spin_lock_init(&lslist_lock);
+
+	error = kset_register(&dlm_kset);
+	if (error)
+		printk("dlm_lockspace_init: cannot register kset %d\n", error);
+	return error;
+}
+
+void dlm_lockspace_exit(void)
+{
+	kset_unregister(&dlm_kset);
+}
+
+static int dlm_scand(void *data)
+{
+	struct dlm_ls *ls;
+
+	while (!kthread_should_stop()) {
+		list_for_each_entry(ls, &lslist, ls_list)
+			dlm_scan_rsbs(ls);
+		schedule_timeout_interruptible(dlm_config.scan_secs * HZ);
+	}
+	return 0;
+}
+
+static int dlm_scand_start(void)
+{
+	struct task_struct *p;
+	int error = 0;
+
+	p = kthread_run(dlm_scand, NULL, "dlm_scand");
+	if (IS_ERR(p))
+		error = PTR_ERR(p);
+	else
+		scand_task = p;
+	return error;
+}
+
+static void dlm_scand_stop(void)
+{
+	kthread_stop(scand_task);
+}
+
+static struct dlm_ls *dlm_find_lockspace_name(char *name, int namelen)
+{
+	struct dlm_ls *ls;
+
+	spin_lock(&lslist_lock);
+
+	list_for_each_entry(ls, &lslist, ls_list) {
+		if (ls->ls_namelen == namelen &&
+		    memcmp(ls->ls_name, name, namelen) == 0)
+			goto out;
+	}
+	ls = NULL;
+ out:
+	spin_unlock(&lslist_lock);
+	return ls;
+}
+
+struct dlm_ls *dlm_find_lockspace_global(uint32_t id)
+{
+	struct dlm_ls *ls;
+
+	spin_lock(&lslist_lock);
+
+	list_for_each_entry(ls, &lslist, ls_list) {
+		if (ls->ls_global_id == id) {
+			ls->ls_count++;
+			goto out;
+		}
+	}
+	ls = NULL;
+ out:
+	spin_unlock(&lslist_lock);
+	return ls;
+}
+
+struct dlm_ls *dlm_find_lockspace_local(void *id)
+{
+	struct dlm_ls *ls = id;
+
+	spin_lock(&lslist_lock);
+	ls->ls_count++;
+	spin_unlock(&lslist_lock);
+	return ls;
+}
+
+void dlm_put_lockspace(struct dlm_ls *ls)
+{
+	spin_lock(&lslist_lock);
+	ls->ls_count--;
+	spin_unlock(&lslist_lock);
+}
+
+static void remove_lockspace(struct dlm_ls *ls)
+{
+	for (;;) {
+		spin_lock(&lslist_lock);
+		if (ls->ls_count == 0) {
+			list_del(&ls->ls_list);
+			spin_unlock(&lslist_lock);
+			return;
+		}
+		spin_unlock(&lslist_lock);
+		ssleep(1);
+	}
+}
+
+static int threads_start(void)
+{
+	int error;
+
+	/* Thread which process lock requests for all lockspace's */
+	error = dlm_astd_start();
+	if (error) {
+		log_print("cannot start dlm_astd thread %d", error);
+		goto fail;
+	}
+
+	error = dlm_scand_start();
+	if (error) {
+		log_print("cannot start dlm_scand thread %d", error);
+		goto astd_fail;
+	}
+
+	/* Thread for sending/receiving messages for all lockspace's */
+	error = dlm_lowcomms_start();
+	if (error) {
+		log_print("cannot start dlm lowcomms %d", error);
+		goto scand_fail;
+	}
+
+	return 0;
+
+ scand_fail:
+	dlm_scand_stop();
+ astd_fail:
+	dlm_astd_stop();
+ fail:
+	return error;
+}
+
+static void threads_stop(void)
+{
+	dlm_scand_stop();
+	dlm_lowcomms_stop();
+	dlm_astd_stop();
+}
+
+static int new_lockspace(char *name, int namelen, void **lockspace,
+			 uint32_t flags, int lvblen)
+{
+	struct dlm_ls *ls;
+	int i, size, error = -ENOMEM;
+
+	if (namelen > DLM_LOCKSPACE_LEN)
+		return -EINVAL;
+
+	if (!lvblen || (lvblen % 8))
+		return -EINVAL;
+
+	if (!try_module_get(THIS_MODULE))
+		return -EINVAL;
+
+	ls = dlm_find_lockspace_name(name, namelen);
+	if (ls) {
+		*lockspace = ls;
+		module_put(THIS_MODULE);
+		return -EEXIST;
+	}
+
+	ls = kmalloc(sizeof(struct dlm_ls) + namelen, GFP_KERNEL);
+	if (!ls)
+		goto out;
+	memset(ls, 0, sizeof(struct dlm_ls) + namelen);
+	memcpy(ls->ls_name, name, namelen);
+	ls->ls_namelen = namelen;
+	ls->ls_exflags = flags;
+	ls->ls_lvblen = lvblen;
+	ls->ls_count = 0;
+	ls->ls_flags = 0;
+
+	size = dlm_config.rsbtbl_size;
+	ls->ls_rsbtbl_size = size;
+
+	ls->ls_rsbtbl = kmalloc(sizeof(struct dlm_rsbtable) * size, GFP_KERNEL);
+	if (!ls->ls_rsbtbl)
+		goto out_lsfree;
+	for (i = 0; i < size; i++) {
+		INIT_LIST_HEAD(&ls->ls_rsbtbl[i].list);
+		INIT_LIST_HEAD(&ls->ls_rsbtbl[i].toss);
+		rwlock_init(&ls->ls_rsbtbl[i].lock);
+	}
+
+	size = dlm_config.lkbtbl_size;
+	ls->ls_lkbtbl_size = size;
+
+	ls->ls_lkbtbl = kmalloc(sizeof(struct dlm_lkbtable) * size, GFP_KERNEL);
+	if (!ls->ls_lkbtbl)
+		goto out_rsbfree;
+	for (i = 0; i < size; i++) {
+		INIT_LIST_HEAD(&ls->ls_lkbtbl[i].list);
+		rwlock_init(&ls->ls_lkbtbl[i].lock);
+		ls->ls_lkbtbl[i].counter = 1;
+	}
+
+	size = dlm_config.dirtbl_size;
+	ls->ls_dirtbl_size = size;
+
+	ls->ls_dirtbl = kmalloc(sizeof(struct dlm_dirtable) * size, GFP_KERNEL);
+	if (!ls->ls_dirtbl)
+		goto out_lkbfree;
+	for (i = 0; i < size; i++) {
+		INIT_LIST_HEAD(&ls->ls_dirtbl[i].list);
+		rwlock_init(&ls->ls_dirtbl[i].lock);
+	}
+
+	INIT_LIST_HEAD(&ls->ls_waiters);
+	init_MUTEX(&ls->ls_waiters_sem);
+
+	INIT_LIST_HEAD(&ls->ls_nodes);
+	INIT_LIST_HEAD(&ls->ls_nodes_gone);
+	ls->ls_num_nodes = 0;
+	ls->ls_low_nodeid = 0;
+	ls->ls_total_weight = 0;
+	ls->ls_node_array = NULL;
+
+	memset(&ls->ls_stub_rsb, 0, sizeof(struct dlm_rsb));
+	ls->ls_stub_rsb.res_ls = ls;
+
+	ls->ls_debug_dentry = NULL;
+
+	init_waitqueue_head(&ls->ls_uevent_wait);
+	ls->ls_uevent_result = 0;
+
+	ls->ls_recoverd_task = NULL;
+	init_MUTEX(&ls->ls_recoverd_active);
+	spin_lock_init(&ls->ls_recover_lock);
+	ls->ls_recover_status = 0;
+	ls->ls_recover_seq = 0;
+	ls->ls_recover_args = NULL;
+	init_rwsem(&ls->ls_in_recovery);
+	INIT_LIST_HEAD(&ls->ls_requestqueue);
+	init_MUTEX(&ls->ls_requestqueue_lock);
+
+	ls->ls_recover_buf = kmalloc(dlm_config.buffer_size, GFP_KERNEL);
+	if (!ls->ls_recover_buf)
+		goto out_dirfree;
+
+	INIT_LIST_HEAD(&ls->ls_recover_list);
+	spin_lock_init(&ls->ls_recover_list_lock);
+	ls->ls_recover_list_count = 0;
+	init_waitqueue_head(&ls->ls_wait_general);
+	INIT_LIST_HEAD(&ls->ls_root_list);
+	init_rwsem(&ls->ls_root_sem);
+
+	down_write(&ls->ls_in_recovery);
+
+	error = dlm_recoverd_start(ls);
+	if (error) {
+		log_error(ls, "can't start dlm_recoverd %d", error);
+		goto out_rcomfree;
+	}
+
+	spin_lock(&lslist_lock);
+	list_add(&ls->ls_list, &lslist);
+	spin_unlock(&lslist_lock);
+
+	dlm_create_debug_file(ls);
+
+	error = kobject_setup(ls);
+	if (error)
+		goto out_del;
+
+	error = kobject_register(&ls->ls_kobj);
+	if (error)
+		goto out_del;
+
+	error = do_uevent(ls, 1);
+	if (error)
+		goto out_unreg;
+
+	*lockspace = ls;
+	return 0;
+
+ out_unreg:
+	kobject_unregister(&ls->ls_kobj);
+ out_del:
+	dlm_delete_debug_file(ls);
+	spin_lock(&lslist_lock);
+	list_del(&ls->ls_list);
+	spin_unlock(&lslist_lock);
+	dlm_recoverd_stop(ls);
+ out_rcomfree:
+	kfree(ls->ls_recover_buf);
+ out_dirfree:
+	kfree(ls->ls_dirtbl);
+ out_lkbfree:
+	kfree(ls->ls_lkbtbl);
+ out_rsbfree:
+	kfree(ls->ls_rsbtbl);
+ out_lsfree:
+	kfree(ls);
+ out:
+	module_put(THIS_MODULE);
+	return error;
+}
+
+int dlm_new_lockspace(char *name, int namelen, void **lockspace,
+		      uint32_t flags, int lvblen)
+{
+	int error = 0;
+
+	down(&ls_lock);
+	if (!ls_count)
+		error = threads_start();
+	if (error)
+		goto out;
+
+	error = new_lockspace(name, namelen, lockspace, flags, lvblen);
+	if (!error)
+		ls_count++;
+ out:
+	up(&ls_lock);
+	return error;
+}
+
+/* Return 1 if the lockspace still has active remote locks,
+ *        2 if the lockspace still has active local locks.
+ */
+static int lockspace_busy(struct dlm_ls *ls)
+{
+	int i, lkb_found = 0;
+	struct dlm_lkb *lkb;
+
+	/* NOTE: We check the lockidtbl here rather than the resource table.
+	   This is because there may be LKBs queued as ASTs that have been
+	   unlinked from their RSBs and are pending deletion once the AST has
+	   been delivered */
+
+	for (i = 0; i < ls->ls_lkbtbl_size; i++) {
+		read_lock(&ls->ls_lkbtbl[i].lock);
+		if (!list_empty(&ls->ls_lkbtbl[i].list)) {
+			lkb_found = 1;
+			list_for_each_entry(lkb, &ls->ls_lkbtbl[i].list,
+					    lkb_idtbl_list) {
+				if (!lkb->lkb_nodeid) {
+					read_unlock(&ls->ls_lkbtbl[i].lock);
+					return 2;
+				}
+			}
+		}
+		read_unlock(&ls->ls_lkbtbl[i].lock);
+	}
+	return lkb_found;
+}
+
+static int release_lockspace(struct dlm_ls *ls, int force)
+{
+	struct dlm_lkb *lkb;
+	struct dlm_rsb *rsb;
+	struct list_head *head;
+	int i;
+	int busy = lockspace_busy(ls);
+
+	if (busy > force)
+		return -EBUSY;
+
+	if (force < 3)
+		do_uevent(ls, 0);
+
+	dlm_recoverd_stop(ls);
+
+	remove_lockspace(ls);
+
+	dlm_delete_debug_file(ls);
+
+	dlm_astd_suspend();
+
+	kfree(ls->ls_recover_buf);
+
+	/*
+	 * Free direntry structs.
+	 */
+
+	dlm_dir_clear(ls);
+	kfree(ls->ls_dirtbl);
+
+	/*
+	 * Free all lkb's on lkbtbl[] lists.
+	 */
+
+	for (i = 0; i < ls->ls_lkbtbl_size; i++) {
+		head = &ls->ls_lkbtbl[i].list;
+		while (!list_empty(head)) {
+			lkb = list_entry(head->next, struct dlm_lkb,
+					 lkb_idtbl_list);
+
+			list_del(&lkb->lkb_idtbl_list);
+
+			dlm_del_ast(lkb);
+
+			if (lkb->lkb_lvbptr && lkb->lkb_flags & DLM_IFL_MSTCPY)
+				free_lvb(lkb->lkb_lvbptr);
+
+			free_lkb(lkb);
+		}
+	}
+	dlm_astd_resume();
+
+	kfree(ls->ls_lkbtbl);
+
+	/*
+	 * Free all rsb's on rsbtbl[] lists
+	 */
+
+	for (i = 0; i < ls->ls_rsbtbl_size; i++) {
+		head = &ls->ls_rsbtbl[i].list;
+		while (!list_empty(head)) {
+			rsb = list_entry(head->next, struct dlm_rsb,
+					 res_hashchain);
+
+			list_del(&rsb->res_hashchain);
+			free_rsb(rsb);
+		}
+
+		head = &ls->ls_rsbtbl[i].toss;
+		while (!list_empty(head)) {
+			rsb = list_entry(head->next, struct dlm_rsb,
+					 res_hashchain);
+			list_del(&rsb->res_hashchain);
+			free_rsb(rsb);
+		}
+	}
+
+	kfree(ls->ls_rsbtbl);
+
+	/*
+	 * Free structures on any other lists
+	 */
+
+	kfree(ls->ls_recover_args);
+	dlm_clear_free_entries(ls);
+	dlm_clear_members(ls);
+	dlm_clear_members_gone(ls);
+	kfree(ls->ls_node_array);
+	kobject_unregister(&ls->ls_kobj);
+	kfree(ls);
+
+	down(&ls_lock);
+	ls_count--;
+	if (!ls_count)
+		threads_stop();
+	up(&ls_lock);
+
+	module_put(THIS_MODULE);
+	return 0;
+}
+
+/*
+ * Called when a system has released all its locks and is not going to use the
+ * lockspace any longer.  We free everything we're managing for this lockspace.
+ * Remaining nodes will go through the recovery process as if we'd died.  The
+ * lockspace must continue to function as usual, participating in recoveries,
+ * until this returns.
+ *
+ * Force has 4 possible values:
+ * 0 - don't destroy locksapce if it has any LKBs
+ * 1 - destroy lockspace if it has remote LKBs but not if it has local LKBs
+ * 2 - destroy lockspace regardless of LKBs
+ * 3 - destroy lockspace as part of a forced shutdown
+ */
+
+int dlm_release_lockspace(void *lockspace, int force)
+{
+	struct dlm_ls *ls;
+
+	ls = dlm_find_lockspace_local(lockspace);
+	if (!ls)
+		return -EINVAL;
+	dlm_put_lockspace(ls);
+	return release_lockspace(ls, force);
+}
+