[PATCH] OCFS2: The Second Oracle Cluster Filesystem
A distributed lock manager built with the cluster file system use case
in mind. The OCFS2 dlm exposes a VMS style API, though things have
been simplified internally. The only lock levels implemented currently
are NLMODE, PRMODE and EXMODE.
Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>
Signed-off-by: Kurt Hackel <kurt.hackel@oracle.com>
diff --git a/fs/ocfs2/dlm/dlmthread.c b/fs/ocfs2/dlm/dlmthread.c
new file mode 100644
index 0000000..92cd5cd
--- /dev/null
+++ b/fs/ocfs2/dlm/dlmthread.c
@@ -0,0 +1,695 @@
+/* -*- mode: c; c-basic-offset: 8; -*-
+ * vim: noexpandtab sw=8 ts=8 sts=0:
+ *
+ * dlmthread.c
+ *
+ * standalone DLM module
+ *
+ * Copyright (C) 2004 Oracle. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this program; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 021110-1307, USA.
+ *
+ */
+
+
+#include <linux/module.h>
+#include <linux/fs.h>
+#include <linux/types.h>
+#include <linux/slab.h>
+#include <linux/highmem.h>
+#include <linux/utsname.h>
+#include <linux/init.h>
+#include <linux/sysctl.h>
+#include <linux/random.h>
+#include <linux/blkdev.h>
+#include <linux/socket.h>
+#include <linux/inet.h>
+#include <linux/timer.h>
+#include <linux/kthread.h>
+
+
+#include "cluster/heartbeat.h"
+#include "cluster/nodemanager.h"
+#include "cluster/tcp.h"
+
+#include "dlmapi.h"
+#include "dlmcommon.h"
+#include "dlmdomain.h"
+
+#define MLOG_MASK_PREFIX (ML_DLM|ML_DLM_THREAD)
+#include "cluster/masklog.h"
+
+extern spinlock_t dlm_domain_lock;
+extern struct list_head dlm_domains;
+
+static int dlm_thread(void *data);
+
+static void dlm_flush_asts(struct dlm_ctxt *dlm);
+
+#define dlm_lock_is_remote(dlm, lock) ((lock)->ml.node != (dlm)->node_num)
+
+/* will exit holding res->spinlock, but may drop in function */
+/* waits until flags are cleared on res->state */
+void __dlm_wait_on_lockres_flags(struct dlm_lock_resource *res, int flags)
+{
+ DECLARE_WAITQUEUE(wait, current);
+
+ assert_spin_locked(&res->spinlock);
+
+ add_wait_queue(&res->wq, &wait);
+repeat:
+ set_current_state(TASK_UNINTERRUPTIBLE);
+ if (res->state & flags) {
+ spin_unlock(&res->spinlock);
+ schedule();
+ spin_lock(&res->spinlock);
+ goto repeat;
+ }
+ remove_wait_queue(&res->wq, &wait);
+ current->state = TASK_RUNNING;
+}
+
+
+static int __dlm_lockres_unused(struct dlm_lock_resource *res)
+{
+ if (list_empty(&res->granted) &&
+ list_empty(&res->converting) &&
+ list_empty(&res->blocked) &&
+ list_empty(&res->dirty))
+ return 1;
+ return 0;
+}
+
+
+/* Call whenever you may have added or deleted something from one of
+ * the lockres queue's. This will figure out whether it belongs on the
+ * unused list or not and does the appropriate thing. */
+void __dlm_lockres_calc_usage(struct dlm_ctxt *dlm,
+ struct dlm_lock_resource *res)
+{
+ mlog_entry("%.*s\n", res->lockname.len, res->lockname.name);
+
+ assert_spin_locked(&dlm->spinlock);
+ assert_spin_locked(&res->spinlock);
+
+ if (__dlm_lockres_unused(res)){
+ if (list_empty(&res->purge)) {
+ mlog(0, "putting lockres %.*s from purge list\n",
+ res->lockname.len, res->lockname.name);
+
+ res->last_used = jiffies;
+ list_add_tail(&res->purge, &dlm->purge_list);
+ dlm->purge_count++;
+ }
+ } else if (!list_empty(&res->purge)) {
+ mlog(0, "removing lockres %.*s from purge list\n",
+ res->lockname.len, res->lockname.name);
+
+ list_del_init(&res->purge);
+ dlm->purge_count--;
+ }
+}
+
+void dlm_lockres_calc_usage(struct dlm_ctxt *dlm,
+ struct dlm_lock_resource *res)
+{
+ mlog_entry("%.*s\n", res->lockname.len, res->lockname.name);
+ spin_lock(&dlm->spinlock);
+ spin_lock(&res->spinlock);
+
+ __dlm_lockres_calc_usage(dlm, res);
+
+ spin_unlock(&res->spinlock);
+ spin_unlock(&dlm->spinlock);
+}
+
+/* TODO: Eventual API: Called with the dlm spinlock held, may drop it
+ * to do migration, but will re-acquire before exit. */
+void dlm_purge_lockres(struct dlm_ctxt *dlm, struct dlm_lock_resource *lockres)
+{
+ int master;
+ int ret;
+
+ spin_lock(&lockres->spinlock);
+ master = lockres->owner == dlm->node_num;
+ spin_unlock(&lockres->spinlock);
+
+ mlog(0, "purging lockres %.*s, master = %d\n", lockres->lockname.len,
+ lockres->lockname.name, master);
+
+ /* Non master is the easy case -- no migration required, just
+ * quit. */
+ if (!master)
+ goto finish;
+
+ /* Wheee! Migrate lockres here! */
+ spin_unlock(&dlm->spinlock);
+again:
+
+ ret = dlm_migrate_lockres(dlm, lockres, O2NM_MAX_NODES);
+ if (ret == -ENOTEMPTY) {
+ mlog(ML_ERROR, "lockres %.*s still has local locks!\n",
+ lockres->lockname.len, lockres->lockname.name);
+
+ BUG();
+ } else if (ret < 0) {
+ mlog(ML_NOTICE, "lockres %.*s: migrate failed, retrying\n",
+ lockres->lockname.len, lockres->lockname.name);
+ goto again;
+ }
+
+ spin_lock(&dlm->spinlock);
+
+finish:
+ if (!list_empty(&lockres->purge)) {
+ list_del_init(&lockres->purge);
+ dlm->purge_count--;
+ }
+ __dlm_unhash_lockres(lockres);
+}
+
+static void dlm_run_purge_list(struct dlm_ctxt *dlm,
+ int purge_now)
+{
+ unsigned int run_max, unused;
+ unsigned long purge_jiffies;
+ struct dlm_lock_resource *lockres;
+
+ spin_lock(&dlm->spinlock);
+ run_max = dlm->purge_count;
+
+ while(run_max && !list_empty(&dlm->purge_list)) {
+ run_max--;
+
+ lockres = list_entry(dlm->purge_list.next,
+ struct dlm_lock_resource, purge);
+
+ /* Status of the lockres *might* change so double
+ * check. If the lockres is unused, holding the dlm
+ * spinlock will prevent people from getting and more
+ * refs on it -- there's no need to keep the lockres
+ * spinlock. */
+ spin_lock(&lockres->spinlock);
+ unused = __dlm_lockres_unused(lockres);
+ spin_unlock(&lockres->spinlock);
+
+ if (!unused)
+ continue;
+
+ purge_jiffies = lockres->last_used +
+ msecs_to_jiffies(DLM_PURGE_INTERVAL_MS);
+
+ /* Make sure that we want to be processing this guy at
+ * this time. */
+ if (!purge_now && time_after(purge_jiffies, jiffies)) {
+ /* Since resources are added to the purge list
+ * in tail order, we can stop at the first
+ * unpurgable resource -- anyone added after
+ * him will have a greater last_used value */
+ break;
+ }
+
+ list_del_init(&lockres->purge);
+ dlm->purge_count--;
+
+ /* This may drop and reacquire the dlm spinlock if it
+ * has to do migration. */
+ mlog(0, "calling dlm_purge_lockres!\n");
+ dlm_purge_lockres(dlm, lockres);
+ mlog(0, "DONE calling dlm_purge_lockres!\n");
+
+ /* Avoid adding any scheduling latencies */
+ cond_resched_lock(&dlm->spinlock);
+ }
+
+ spin_unlock(&dlm->spinlock);
+}
+
+static void dlm_shuffle_lists(struct dlm_ctxt *dlm,
+ struct dlm_lock_resource *res)
+{
+ struct dlm_lock *lock, *target;
+ struct list_head *iter;
+ struct list_head *head;
+ int can_grant = 1;
+
+ //mlog(0, "res->lockname.len=%d\n", res->lockname.len);
+ //mlog(0, "res->lockname.name=%p\n", res->lockname.name);
+ //mlog(0, "shuffle res %.*s\n", res->lockname.len,
+ // res->lockname.name);
+
+ /* because this function is called with the lockres
+ * spinlock, and because we know that it is not migrating/
+ * recovering/in-progress, it is fine to reserve asts and
+ * basts right before queueing them all throughout */
+ assert_spin_locked(&res->spinlock);
+ BUG_ON((res->state & (DLM_LOCK_RES_MIGRATING|
+ DLM_LOCK_RES_RECOVERING|
+ DLM_LOCK_RES_IN_PROGRESS)));
+
+converting:
+ if (list_empty(&res->converting))
+ goto blocked;
+ mlog(0, "res %.*s has locks on a convert queue\n", res->lockname.len,
+ res->lockname.name);
+
+ target = list_entry(res->converting.next, struct dlm_lock, list);
+ if (target->ml.convert_type == LKM_IVMODE) {
+ mlog(ML_ERROR, "%.*s: converting a lock with no "
+ "convert_type!\n", res->lockname.len, res->lockname.name);
+ BUG();
+ }
+ head = &res->granted;
+ list_for_each(iter, head) {
+ lock = list_entry(iter, struct dlm_lock, list);
+ if (lock==target)
+ continue;
+ if (!dlm_lock_compatible(lock->ml.type,
+ target->ml.convert_type)) {
+ can_grant = 0;
+ /* queue the BAST if not already */
+ if (lock->ml.highest_blocked == LKM_IVMODE) {
+ __dlm_lockres_reserve_ast(res);
+ dlm_queue_bast(dlm, lock);
+ }
+ /* update the highest_blocked if needed */
+ if (lock->ml.highest_blocked < target->ml.convert_type)
+ lock->ml.highest_blocked =
+ target->ml.convert_type;
+ }
+ }
+ head = &res->converting;
+ list_for_each(iter, head) {
+ lock = list_entry(iter, struct dlm_lock, list);
+ if (lock==target)
+ continue;
+ if (!dlm_lock_compatible(lock->ml.type,
+ target->ml.convert_type)) {
+ can_grant = 0;
+ if (lock->ml.highest_blocked == LKM_IVMODE) {
+ __dlm_lockres_reserve_ast(res);
+ dlm_queue_bast(dlm, lock);
+ }
+ if (lock->ml.highest_blocked < target->ml.convert_type)
+ lock->ml.highest_blocked =
+ target->ml.convert_type;
+ }
+ }
+
+ /* we can convert the lock */
+ if (can_grant) {
+ spin_lock(&target->spinlock);
+ BUG_ON(target->ml.highest_blocked != LKM_IVMODE);
+
+ mlog(0, "calling ast for converting lock: %.*s, have: %d, "
+ "granting: %d, node: %u\n", res->lockname.len,
+ res->lockname.name, target->ml.type,
+ target->ml.convert_type, target->ml.node);
+
+ target->ml.type = target->ml.convert_type;
+ target->ml.convert_type = LKM_IVMODE;
+ list_del_init(&target->list);
+ list_add_tail(&target->list, &res->granted);
+
+ BUG_ON(!target->lksb);
+ target->lksb->status = DLM_NORMAL;
+
+ spin_unlock(&target->spinlock);
+
+ __dlm_lockres_reserve_ast(res);
+ dlm_queue_ast(dlm, target);
+ /* go back and check for more */
+ goto converting;
+ }
+
+blocked:
+ if (list_empty(&res->blocked))
+ goto leave;
+ target = list_entry(res->blocked.next, struct dlm_lock, list);
+
+ head = &res->granted;
+ list_for_each(iter, head) {
+ lock = list_entry(iter, struct dlm_lock, list);
+ if (lock==target)
+ continue;
+ if (!dlm_lock_compatible(lock->ml.type, target->ml.type)) {
+ can_grant = 0;
+ if (lock->ml.highest_blocked == LKM_IVMODE) {
+ __dlm_lockres_reserve_ast(res);
+ dlm_queue_bast(dlm, lock);
+ }
+ if (lock->ml.highest_blocked < target->ml.type)
+ lock->ml.highest_blocked = target->ml.type;
+ }
+ }
+
+ head = &res->converting;
+ list_for_each(iter, head) {
+ lock = list_entry(iter, struct dlm_lock, list);
+ if (lock==target)
+ continue;
+ if (!dlm_lock_compatible(lock->ml.type, target->ml.type)) {
+ can_grant = 0;
+ if (lock->ml.highest_blocked == LKM_IVMODE) {
+ __dlm_lockres_reserve_ast(res);
+ dlm_queue_bast(dlm, lock);
+ }
+ if (lock->ml.highest_blocked < target->ml.type)
+ lock->ml.highest_blocked = target->ml.type;
+ }
+ }
+
+ /* we can grant the blocked lock (only
+ * possible if converting list empty) */
+ if (can_grant) {
+ spin_lock(&target->spinlock);
+ BUG_ON(target->ml.highest_blocked != LKM_IVMODE);
+
+ mlog(0, "calling ast for blocked lock: %.*s, granting: %d, "
+ "node: %u\n", res->lockname.len, res->lockname.name,
+ target->ml.type, target->ml.node);
+
+ // target->ml.type is already correct
+ list_del_init(&target->list);
+ list_add_tail(&target->list, &res->granted);
+
+ BUG_ON(!target->lksb);
+ target->lksb->status = DLM_NORMAL;
+
+ spin_unlock(&target->spinlock);
+
+ __dlm_lockres_reserve_ast(res);
+ dlm_queue_ast(dlm, target);
+ /* go back and check for more */
+ goto converting;
+ }
+
+leave:
+ return;
+}
+
+/* must have NO locks when calling this with res !=NULL * */
+void dlm_kick_thread(struct dlm_ctxt *dlm, struct dlm_lock_resource *res)
+{
+ mlog_entry("dlm=%p, res=%p\n", dlm, res);
+ if (res) {
+ spin_lock(&dlm->spinlock);
+ spin_lock(&res->spinlock);
+ __dlm_dirty_lockres(dlm, res);
+ spin_unlock(&res->spinlock);
+ spin_unlock(&dlm->spinlock);
+ }
+ wake_up(&dlm->dlm_thread_wq);
+}
+
+void __dlm_dirty_lockres(struct dlm_ctxt *dlm, struct dlm_lock_resource *res)
+{
+ mlog_entry("dlm=%p, res=%p\n", dlm, res);
+
+ assert_spin_locked(&dlm->spinlock);
+ assert_spin_locked(&res->spinlock);
+
+ /* don't shuffle secondary queues */
+ if ((res->owner == dlm->node_num) &&
+ !(res->state & DLM_LOCK_RES_DIRTY)) {
+ list_add_tail(&res->dirty, &dlm->dirty_list);
+ res->state |= DLM_LOCK_RES_DIRTY;
+ }
+}
+
+
+/* Launch the NM thread for the mounted volume */
+int dlm_launch_thread(struct dlm_ctxt *dlm)
+{
+ mlog(0, "starting dlm thread...\n");
+
+ dlm->dlm_thread_task = kthread_run(dlm_thread, dlm, "dlm_thread");
+ if (IS_ERR(dlm->dlm_thread_task)) {
+ mlog_errno(PTR_ERR(dlm->dlm_thread_task));
+ dlm->dlm_thread_task = NULL;
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
+void dlm_complete_thread(struct dlm_ctxt *dlm)
+{
+ if (dlm->dlm_thread_task) {
+ mlog(ML_KTHREAD, "waiting for dlm thread to exit\n");
+ kthread_stop(dlm->dlm_thread_task);
+ dlm->dlm_thread_task = NULL;
+ }
+}
+
+static int dlm_dirty_list_empty(struct dlm_ctxt *dlm)
+{
+ int empty;
+
+ spin_lock(&dlm->spinlock);
+ empty = list_empty(&dlm->dirty_list);
+ spin_unlock(&dlm->spinlock);
+
+ return empty;
+}
+
+static void dlm_flush_asts(struct dlm_ctxt *dlm)
+{
+ int ret;
+ struct dlm_lock *lock;
+ struct dlm_lock_resource *res;
+ u8 hi;
+
+ spin_lock(&dlm->ast_lock);
+ while (!list_empty(&dlm->pending_asts)) {
+ lock = list_entry(dlm->pending_asts.next,
+ struct dlm_lock, ast_list);
+ /* get an extra ref on lock */
+ dlm_lock_get(lock);
+ res = lock->lockres;
+ mlog(0, "delivering an ast for this lockres\n");
+
+ BUG_ON(!lock->ast_pending);
+
+ /* remove from list (including ref) */
+ list_del_init(&lock->ast_list);
+ dlm_lock_put(lock);
+ spin_unlock(&dlm->ast_lock);
+
+ if (lock->ml.node != dlm->node_num) {
+ ret = dlm_do_remote_ast(dlm, res, lock);
+ if (ret < 0)
+ mlog_errno(ret);
+ } else
+ dlm_do_local_ast(dlm, res, lock);
+
+ spin_lock(&dlm->ast_lock);
+
+ /* possible that another ast was queued while
+ * we were delivering the last one */
+ if (!list_empty(&lock->ast_list)) {
+ mlog(0, "aha another ast got queued while "
+ "we were finishing the last one. will "
+ "keep the ast_pending flag set.\n");
+ } else
+ lock->ast_pending = 0;
+
+ /* drop the extra ref.
+ * this may drop it completely. */
+ dlm_lock_put(lock);
+ dlm_lockres_release_ast(dlm, res);
+ }
+
+ while (!list_empty(&dlm->pending_basts)) {
+ lock = list_entry(dlm->pending_basts.next,
+ struct dlm_lock, bast_list);
+ /* get an extra ref on lock */
+ dlm_lock_get(lock);
+ res = lock->lockres;
+
+ BUG_ON(!lock->bast_pending);
+
+ /* get the highest blocked lock, and reset */
+ spin_lock(&lock->spinlock);
+ BUG_ON(lock->ml.highest_blocked <= LKM_IVMODE);
+ hi = lock->ml.highest_blocked;
+ lock->ml.highest_blocked = LKM_IVMODE;
+ spin_unlock(&lock->spinlock);
+
+ /* remove from list (including ref) */
+ list_del_init(&lock->bast_list);
+ dlm_lock_put(lock);
+ spin_unlock(&dlm->ast_lock);
+
+ mlog(0, "delivering a bast for this lockres "
+ "(blocked = %d\n", hi);
+
+ if (lock->ml.node != dlm->node_num) {
+ ret = dlm_send_proxy_bast(dlm, res, lock, hi);
+ if (ret < 0)
+ mlog_errno(ret);
+ } else
+ dlm_do_local_bast(dlm, res, lock, hi);
+
+ spin_lock(&dlm->ast_lock);
+
+ /* possible that another bast was queued while
+ * we were delivering the last one */
+ if (!list_empty(&lock->bast_list)) {
+ mlog(0, "aha another bast got queued while "
+ "we were finishing the last one. will "
+ "keep the bast_pending flag set.\n");
+ } else
+ lock->bast_pending = 0;
+
+ /* drop the extra ref.
+ * this may drop it completely. */
+ dlm_lock_put(lock);
+ dlm_lockres_release_ast(dlm, res);
+ }
+ wake_up(&dlm->ast_wq);
+ spin_unlock(&dlm->ast_lock);
+}
+
+
+#define DLM_THREAD_TIMEOUT_MS (4 * 1000)
+#define DLM_THREAD_MAX_DIRTY 100
+#define DLM_THREAD_MAX_ASTS 10
+
+static int dlm_thread(void *data)
+{
+ struct dlm_lock_resource *res;
+ struct dlm_ctxt *dlm = data;
+ unsigned long timeout = msecs_to_jiffies(DLM_THREAD_TIMEOUT_MS);
+
+ mlog(0, "dlm thread running for %s...\n", dlm->name);
+
+ while (!kthread_should_stop()) {
+ int n = DLM_THREAD_MAX_DIRTY;
+
+ /* dlm_shutting_down is very point-in-time, but that
+ * doesn't matter as we'll just loop back around if we
+ * get false on the leading edge of a state
+ * transition. */
+ dlm_run_purge_list(dlm, dlm_shutting_down(dlm));
+
+ /* We really don't want to hold dlm->spinlock while
+ * calling dlm_shuffle_lists on each lockres that
+ * needs to have its queues adjusted and AST/BASTs
+ * run. So let's pull each entry off the dirty_list
+ * and drop dlm->spinlock ASAP. Once off the list,
+ * res->spinlock needs to be taken again to protect
+ * the queues while calling dlm_shuffle_lists. */
+ spin_lock(&dlm->spinlock);
+ while (!list_empty(&dlm->dirty_list)) {
+ int delay = 0;
+ res = list_entry(dlm->dirty_list.next,
+ struct dlm_lock_resource, dirty);
+
+ /* peel a lockres off, remove it from the list,
+ * unset the dirty flag and drop the dlm lock */
+ BUG_ON(!res);
+ dlm_lockres_get(res);
+
+ spin_lock(&res->spinlock);
+ res->state &= ~DLM_LOCK_RES_DIRTY;
+ list_del_init(&res->dirty);
+ spin_unlock(&res->spinlock);
+ spin_unlock(&dlm->spinlock);
+
+ /* lockres can be re-dirtied/re-added to the
+ * dirty_list in this gap, but that is ok */
+
+ spin_lock(&res->spinlock);
+ if (res->owner != dlm->node_num) {
+ __dlm_print_one_lock_resource(res);
+ mlog(ML_ERROR, "inprog:%s, mig:%s, reco:%s, dirty:%s\n",
+ res->state & DLM_LOCK_RES_IN_PROGRESS ? "yes" : "no",
+ res->state & DLM_LOCK_RES_MIGRATING ? "yes" : "no",
+ res->state & DLM_LOCK_RES_RECOVERING ? "yes" : "no",
+ res->state & DLM_LOCK_RES_DIRTY ? "yes" : "no");
+ }
+ BUG_ON(res->owner != dlm->node_num);
+
+ /* it is now ok to move lockreses in these states
+ * to the dirty list, assuming that they will only be
+ * dirty for a short while. */
+ if (res->state & (DLM_LOCK_RES_IN_PROGRESS |
+ DLM_LOCK_RES_MIGRATING |
+ DLM_LOCK_RES_RECOVERING)) {
+ /* move it to the tail and keep going */
+ spin_unlock(&res->spinlock);
+ mlog(0, "delaying list shuffling for in-"
+ "progress lockres %.*s, state=%d\n",
+ res->lockname.len, res->lockname.name,
+ res->state);
+ delay = 1;
+ goto in_progress;
+ }
+
+ /* at this point the lockres is not migrating/
+ * recovering/in-progress. we have the lockres
+ * spinlock and do NOT have the dlm lock.
+ * safe to reserve/queue asts and run the lists. */
+
+ mlog(0, "calling dlm_shuffle_lists with dlm=%p, "
+ "res=%p\n", dlm, res);
+
+ /* called while holding lockres lock */
+ dlm_shuffle_lists(dlm, res);
+ spin_unlock(&res->spinlock);
+
+ dlm_lockres_calc_usage(dlm, res);
+
+in_progress:
+
+ spin_lock(&dlm->spinlock);
+ /* if the lock was in-progress, stick
+ * it on the back of the list */
+ if (delay) {
+ spin_lock(&res->spinlock);
+ list_add_tail(&res->dirty, &dlm->dirty_list);
+ res->state |= DLM_LOCK_RES_DIRTY;
+ spin_unlock(&res->spinlock);
+ }
+ dlm_lockres_put(res);
+
+ /* unlikely, but we may need to give time to
+ * other tasks */
+ if (!--n) {
+ mlog(0, "throttling dlm_thread\n");
+ break;
+ }
+ }
+
+ spin_unlock(&dlm->spinlock);
+ dlm_flush_asts(dlm);
+
+ /* yield and continue right away if there is more work to do */
+ if (!n) {
+ yield();
+ continue;
+ }
+
+ wait_event_interruptible_timeout(dlm->dlm_thread_wq,
+ !dlm_dirty_list_empty(dlm) ||
+ kthread_should_stop(),
+ timeout);
+ }
+
+ mlog(0, "quitting DLM thread\n");
+ return 0;
+}