dlmthread.c

linux 内核源代码

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_move_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)) {
		if (res->state & (DLM_LOCK_RES_MIGRATING |
				  DLM_LOCK_RES_BLOCK_DIRTY))
		    return;

		if (list_empty(&res->dirty)) {
			/* ref for dirty_list */
			dlm_lockres_get(res);
			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);
			/* We clear the DLM_LOCK_RES_DIRTY state once we shuffle lists below */
			list_del_init(&res->dirty);
			spin_unlock(&res->spinlock);
			spin_unlock(&dlm->spinlock);
			/* Drop dirty_list ref */
			dlm_lockres_put(res);

		 	/* 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. */
			BUG_ON(res->state & DLM_LOCK_RES_MIGRATING);
			if (res->state & (DLM_LOCK_RES_IN_PROGRESS |
					  DLM_LOCK_RES_RECOVERING)) {
				/* move it to the tail and keep going */
				res->state &= ~DLM_LOCK_RES_DIRTY;
				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=%s, "
			     "res=%.*s\n", dlm->name,
			     res->lockname.len, res->lockname.name);

			/* called while holding lockres lock */
			dlm_shuffle_lists(dlm, res);
			res->state &= ~DLM_LOCK_RES_DIRTY;
			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);
				__dlm_dirty_lockres(dlm, res);
				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) {
			cond_resched();
			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;
}