Example #1
0
/*
 * process events that have been sent to an object's state machine
 * - initiates parent lookup
 * - does object lookup
 * - does object creation
 * - does object recycling and retirement
 * - does object withdrawal
 */
static void fscache_object_state_machine(struct fscache_object *object)
{
	enum fscache_object_state new_state;
	struct fscache_cookie *cookie;

	ASSERT(object != NULL);

	_enter("{OBJ%x,%s,%lx}",
	       object->debug_id, fscache_object_states[object->state],
	       object->events);

	switch (object->state) {
		/* wait for the parent object to become ready */
	case FSCACHE_OBJECT_INIT:
		object->event_mask =
			ULONG_MAX & ~(1 << FSCACHE_OBJECT_EV_CLEARED);
		fscache_initialise_object(object);
		goto done;

		/* look up the object metadata on disk */
	case FSCACHE_OBJECT_LOOKING_UP:
		fscache_lookup_object(object);
		goto lookup_transit;

		/* create the object metadata on disk */
	case FSCACHE_OBJECT_CREATING:
		fscache_lookup_object(object);
		goto lookup_transit;

		/* handle an object becoming available; start pending
		 * operations and queue dependent operations for processing */
	case FSCACHE_OBJECT_AVAILABLE:
		fscache_object_available(object);
		goto active_transit;

		/* normal running state */
	case FSCACHE_OBJECT_ACTIVE:
		goto active_transit;

		/* Invalidate an object on disk */
	case FSCACHE_OBJECT_INVALIDATING:
		clear_bit(FSCACHE_OBJECT_EV_INVALIDATE, &object->events);
		fscache_stat(&fscache_n_invalidates_run);
		fscache_stat(&fscache_n_cop_invalidate_object);
		fscache_invalidate_object(object);
		fscache_stat_d(&fscache_n_cop_invalidate_object);
		fscache_raise_event(object, FSCACHE_OBJECT_EV_UPDATE);
		goto active_transit;

		/* update the object metadata on disk */
	case FSCACHE_OBJECT_UPDATING:
		clear_bit(FSCACHE_OBJECT_EV_UPDATE, &object->events);
		fscache_stat(&fscache_n_updates_run);
		fscache_stat(&fscache_n_cop_update_object);
		object->cache->ops->update_object(object);
		fscache_stat_d(&fscache_n_cop_update_object);
		goto active_transit;

		/* handle an object dying during lookup or creation */
	case FSCACHE_OBJECT_LC_DYING:
		object->event_mask &= ~(1 << FSCACHE_OBJECT_EV_UPDATE);
		fscache_stat(&fscache_n_cop_lookup_complete);
		object->cache->ops->lookup_complete(object);
		fscache_stat_d(&fscache_n_cop_lookup_complete);

		spin_lock(&object->lock);
		object->state = FSCACHE_OBJECT_DYING;
		cookie = object->cookie;
		if (cookie) {
			if (test_and_clear_bit(FSCACHE_COOKIE_LOOKING_UP,
					       &cookie->flags))
				wake_up_bit(&cookie->flags,
					    FSCACHE_COOKIE_LOOKING_UP);
			if (test_and_clear_bit(FSCACHE_COOKIE_CREATING,
					       &cookie->flags))
				wake_up_bit(&cookie->flags,
					    FSCACHE_COOKIE_CREATING);
		}
		spin_unlock(&object->lock);

		fscache_done_parent_op(object);

		/* wait for completion of all active operations on this object
		 * and the death of all child objects of this object */
	case FSCACHE_OBJECT_DYING:
	dying:
		clear_bit(FSCACHE_OBJECT_EV_CLEARED, &object->events);
		spin_lock(&object->lock);
		_debug("dying OBJ%x {%d,%d}",
		       object->debug_id, object->n_ops, object->n_children);
		if (object->n_ops == 0 && object->n_children == 0) {
			object->event_mask &=
				~(1 << FSCACHE_OBJECT_EV_CLEARED);
			object->event_mask |=
				(1 << FSCACHE_OBJECT_EV_WITHDRAW) |
				(1 << FSCACHE_OBJECT_EV_RETIRE) |
				(1 << FSCACHE_OBJECT_EV_RELEASE) |
				(1 << FSCACHE_OBJECT_EV_ERROR);
		} else {
			object->event_mask &=
				~((1 << FSCACHE_OBJECT_EV_WITHDRAW) |
				  (1 << FSCACHE_OBJECT_EV_RETIRE) |
				  (1 << FSCACHE_OBJECT_EV_RELEASE) |
				  (1 << FSCACHE_OBJECT_EV_ERROR));
			object->event_mask |=
				1 << FSCACHE_OBJECT_EV_CLEARED;
		}
		spin_unlock(&object->lock);
		fscache_enqueue_dependents(object);
		fscache_start_operations(object);
		goto terminal_transit;

		/* handle an abort during initialisation */
	case FSCACHE_OBJECT_ABORT_INIT:
		_debug("handle abort init %lx", object->events);
		object->event_mask &= ~(1 << FSCACHE_OBJECT_EV_UPDATE);

		spin_lock(&object->lock);
		fscache_dequeue_object(object);

		object->state = FSCACHE_OBJECT_DYING;
		if (test_and_clear_bit(FSCACHE_COOKIE_CREATING,
				       &object->cookie->flags))
			wake_up_bit(&object->cookie->flags,
				    FSCACHE_COOKIE_CREATING);
		spin_unlock(&object->lock);
		goto dying;

		/* handle the netfs releasing an object and possibly marking it
		 * obsolete too */
	case FSCACHE_OBJECT_RELEASING:
	case FSCACHE_OBJECT_RECYCLING:
		object->event_mask &=
			~((1 << FSCACHE_OBJECT_EV_WITHDRAW) |
			  (1 << FSCACHE_OBJECT_EV_RETIRE) |
			  (1 << FSCACHE_OBJECT_EV_RELEASE) |
			  (1 << FSCACHE_OBJECT_EV_ERROR));
		fscache_release_object(object);
		spin_lock(&object->lock);
		object->state = FSCACHE_OBJECT_DEAD;
		spin_unlock(&object->lock);
		fscache_stat(&fscache_n_object_dead);
		goto terminal_transit;

		/* handle the parent cache of this object being withdrawn from
		 * active service */
	case FSCACHE_OBJECT_WITHDRAWING:
		object->event_mask &=
			~((1 << FSCACHE_OBJECT_EV_WITHDRAW) |
			  (1 << FSCACHE_OBJECT_EV_RETIRE) |
			  (1 << FSCACHE_OBJECT_EV_RELEASE) |
			  (1 << FSCACHE_OBJECT_EV_ERROR));
		fscache_withdraw_object(object);
		spin_lock(&object->lock);
		object->state = FSCACHE_OBJECT_DEAD;
		spin_unlock(&object->lock);
		fscache_stat(&fscache_n_object_dead);
		goto terminal_transit;

		/* complain about the object being woken up once it is
		 * deceased */
	case FSCACHE_OBJECT_DEAD:
		printk(KERN_ERR "FS-Cache:"
		       " Unexpected event in dead state %lx\n",
		       object->events & object->event_mask);
		BUG();

	default:
		printk(KERN_ERR "FS-Cache: Unknown object state %u\n",
		       object->state);
		BUG();
	}

	/* determine the transition from a lookup state */
lookup_transit:
	switch (fls(object->events & object->event_mask) - 1) {
	case FSCACHE_OBJECT_EV_WITHDRAW:
	case FSCACHE_OBJECT_EV_RETIRE:
	case FSCACHE_OBJECT_EV_RELEASE:
	case FSCACHE_OBJECT_EV_ERROR:
		new_state = FSCACHE_OBJECT_LC_DYING;
		goto change_state;
	case FSCACHE_OBJECT_EV_REQUEUE:
		goto done;
	case -1:
		goto done; /* sleep until event */
	default:
		goto unsupported_event;
	}

	/* determine the transition from an active state */
active_transit:
	switch (fls(object->events & object->event_mask) - 1) {
	case FSCACHE_OBJECT_EV_WITHDRAW:
	case FSCACHE_OBJECT_EV_RETIRE:
	case FSCACHE_OBJECT_EV_RELEASE:
	case FSCACHE_OBJECT_EV_ERROR:
		new_state = FSCACHE_OBJECT_DYING;
		goto change_state;
	case FSCACHE_OBJECT_EV_INVALIDATE:
		new_state = FSCACHE_OBJECT_INVALIDATING;
		goto change_state;
	case FSCACHE_OBJECT_EV_UPDATE:
		new_state = FSCACHE_OBJECT_UPDATING;
		goto change_state;
	case -1:
		new_state = FSCACHE_OBJECT_ACTIVE;
		goto change_state; /* sleep until event */
	default:
		goto unsupported_event;
	}

	/* determine the transition from a terminal state */
terminal_transit:
	switch (fls(object->events & object->event_mask) - 1) {
	case FSCACHE_OBJECT_EV_WITHDRAW:
		new_state = FSCACHE_OBJECT_WITHDRAWING;
		goto change_state;
	case FSCACHE_OBJECT_EV_RETIRE:
		new_state = FSCACHE_OBJECT_RECYCLING;
		goto change_state;
	case FSCACHE_OBJECT_EV_RELEASE:
		new_state = FSCACHE_OBJECT_RELEASING;
		goto change_state;
	case FSCACHE_OBJECT_EV_ERROR:
		new_state = FSCACHE_OBJECT_WITHDRAWING;
		goto change_state;
	case FSCACHE_OBJECT_EV_CLEARED:
		new_state = FSCACHE_OBJECT_DYING;
		goto change_state;
	case -1:
		goto done; /* sleep until event */
	default:
		goto unsupported_event;
	}

change_state:
	spin_lock(&object->lock);
	object->state = new_state;
	spin_unlock(&object->lock);

done:
	_leave(" [->%s]", fscache_object_states[object->state]);
	return;

unsupported_event:
	printk(KERN_ERR "FS-Cache:"
	       " Unsupported event %lx [mask %lx] in state %s\n",
	       object->events, object->event_mask,
	       fscache_object_states[object->state]);
	BUG();
}
static void fscache_object_state_machine(struct fscache_object *object)
{
	enum fscache_object_state new_state;
	struct fscache_cookie *cookie;

	ASSERT(object != NULL);

	_enter("{OBJ%x,%s,%lx}",
	       object->debug_id, fscache_object_states[object->state],
	       object->events);

	switch (object->state) {
		
	case FSCACHE_OBJECT_INIT:
		object->event_mask =
			ULONG_MAX & ~(1 << FSCACHE_OBJECT_EV_CLEARED);
		fscache_initialise_object(object);
		goto done;

		
	case FSCACHE_OBJECT_LOOKING_UP:
		fscache_lookup_object(object);
		goto lookup_transit;

		
	case FSCACHE_OBJECT_CREATING:
		fscache_lookup_object(object);
		goto lookup_transit;

	case FSCACHE_OBJECT_AVAILABLE:
		fscache_object_available(object);
		goto active_transit;

		
	case FSCACHE_OBJECT_ACTIVE:
		goto active_transit;

		
	case FSCACHE_OBJECT_UPDATING:
		clear_bit(FSCACHE_OBJECT_EV_UPDATE, &object->events);
		fscache_stat(&fscache_n_updates_run);
		fscache_stat(&fscache_n_cop_update_object);
		object->cache->ops->update_object(object);
		fscache_stat_d(&fscache_n_cop_update_object);
		goto active_transit;

		
	case FSCACHE_OBJECT_LC_DYING:
		object->event_mask &= ~(1 << FSCACHE_OBJECT_EV_UPDATE);
		fscache_stat(&fscache_n_cop_lookup_complete);
		object->cache->ops->lookup_complete(object);
		fscache_stat_d(&fscache_n_cop_lookup_complete);

		spin_lock(&object->lock);
		object->state = FSCACHE_OBJECT_DYING;
		cookie = object->cookie;
		if (cookie) {
			if (test_and_clear_bit(FSCACHE_COOKIE_LOOKING_UP,
					       &cookie->flags))
				wake_up_bit(&cookie->flags,
					    FSCACHE_COOKIE_LOOKING_UP);
			if (test_and_clear_bit(FSCACHE_COOKIE_CREATING,
					       &cookie->flags))
				wake_up_bit(&cookie->flags,
					    FSCACHE_COOKIE_CREATING);
		}
		spin_unlock(&object->lock);

		fscache_done_parent_op(object);

	case FSCACHE_OBJECT_DYING:
	dying:
		clear_bit(FSCACHE_OBJECT_EV_CLEARED, &object->events);
		spin_lock(&object->lock);
		_debug("dying OBJ%x {%d,%d}",
		       object->debug_id, object->n_ops, object->n_children);
		if (object->n_ops == 0 && object->n_children == 0) {
			object->event_mask &=
				~(1 << FSCACHE_OBJECT_EV_CLEARED);
			object->event_mask |=
				(1 << FSCACHE_OBJECT_EV_WITHDRAW) |
				(1 << FSCACHE_OBJECT_EV_RETIRE) |
				(1 << FSCACHE_OBJECT_EV_RELEASE) |
				(1 << FSCACHE_OBJECT_EV_ERROR);
		} else {
			object->event_mask &=
				~((1 << FSCACHE_OBJECT_EV_WITHDRAW) |
				  (1 << FSCACHE_OBJECT_EV_RETIRE) |
				  (1 << FSCACHE_OBJECT_EV_RELEASE) |
				  (1 << FSCACHE_OBJECT_EV_ERROR));
			object->event_mask |=
				1 << FSCACHE_OBJECT_EV_CLEARED;
		}
		spin_unlock(&object->lock);
		fscache_enqueue_dependents(object);
		fscache_start_operations(object);
		goto terminal_transit;

		
	case FSCACHE_OBJECT_ABORT_INIT:
		_debug("handle abort init %lx", object->events);
		object->event_mask &= ~(1 << FSCACHE_OBJECT_EV_UPDATE);

		spin_lock(&object->lock);
		fscache_dequeue_object(object);

		object->state = FSCACHE_OBJECT_DYING;
		if (test_and_clear_bit(FSCACHE_COOKIE_CREATING,
				       &object->cookie->flags))
			wake_up_bit(&object->cookie->flags,
				    FSCACHE_COOKIE_CREATING);
		spin_unlock(&object->lock);
		goto dying;

	case FSCACHE_OBJECT_RELEASING:
	case FSCACHE_OBJECT_RECYCLING:
		object->event_mask &=
			~((1 << FSCACHE_OBJECT_EV_WITHDRAW) |
			  (1 << FSCACHE_OBJECT_EV_RETIRE) |
			  (1 << FSCACHE_OBJECT_EV_RELEASE) |
			  (1 << FSCACHE_OBJECT_EV_ERROR));
		fscache_release_object(object);
		spin_lock(&object->lock);
		object->state = FSCACHE_OBJECT_DEAD;
		spin_unlock(&object->lock);
		fscache_stat(&fscache_n_object_dead);
		goto terminal_transit;

	case FSCACHE_OBJECT_WITHDRAWING:
		object->event_mask &=
			~((1 << FSCACHE_OBJECT_EV_WITHDRAW) |
			  (1 << FSCACHE_OBJECT_EV_RETIRE) |
			  (1 << FSCACHE_OBJECT_EV_RELEASE) |
			  (1 << FSCACHE_OBJECT_EV_ERROR));
		fscache_withdraw_object(object);
		spin_lock(&object->lock);
		object->state = FSCACHE_OBJECT_DEAD;
		spin_unlock(&object->lock);
		fscache_stat(&fscache_n_object_dead);
		goto terminal_transit;

	case FSCACHE_OBJECT_DEAD:
		printk(KERN_ERR "FS-Cache:"
		       " Unexpected event in dead state %lx\n",
		       object->events & object->event_mask);
		BUG();

	default:
		printk(KERN_ERR "FS-Cache: Unknown object state %u\n",
		       object->state);
		BUG();
	}

	
lookup_transit:
	switch (fls(object->events & object->event_mask) - 1) {
	case FSCACHE_OBJECT_EV_WITHDRAW:
	case FSCACHE_OBJECT_EV_RETIRE:
	case FSCACHE_OBJECT_EV_RELEASE:
	case FSCACHE_OBJECT_EV_ERROR:
		new_state = FSCACHE_OBJECT_LC_DYING;
		goto change_state;
	case FSCACHE_OBJECT_EV_REQUEUE:
		goto done;
	case -1:
		goto done; 
	default:
		goto unsupported_event;
	}

	
active_transit:
	switch (fls(object->events & object->event_mask) - 1) {
	case FSCACHE_OBJECT_EV_WITHDRAW:
	case FSCACHE_OBJECT_EV_RETIRE:
	case FSCACHE_OBJECT_EV_RELEASE:
	case FSCACHE_OBJECT_EV_ERROR:
		new_state = FSCACHE_OBJECT_DYING;
		goto change_state;
	case FSCACHE_OBJECT_EV_UPDATE:
		new_state = FSCACHE_OBJECT_UPDATING;
		goto change_state;
	case -1:
		new_state = FSCACHE_OBJECT_ACTIVE;
		goto change_state; 
	default:
		goto unsupported_event;
	}

	
terminal_transit:
	switch (fls(object->events & object->event_mask) - 1) {
	case FSCACHE_OBJECT_EV_WITHDRAW:
		new_state = FSCACHE_OBJECT_WITHDRAWING;
		goto change_state;
	case FSCACHE_OBJECT_EV_RETIRE:
		new_state = FSCACHE_OBJECT_RECYCLING;
		goto change_state;
	case FSCACHE_OBJECT_EV_RELEASE:
		new_state = FSCACHE_OBJECT_RELEASING;
		goto change_state;
	case FSCACHE_OBJECT_EV_ERROR:
		new_state = FSCACHE_OBJECT_WITHDRAWING;
		goto change_state;
	case FSCACHE_OBJECT_EV_CLEARED:
		new_state = FSCACHE_OBJECT_DYING;
		goto change_state;
	case -1:
		goto done; 
	default:
		goto unsupported_event;
	}

change_state:
	spin_lock(&object->lock);
	object->state = new_state;
	spin_unlock(&object->lock);

done:
	_leave(" [->%s]", fscache_object_states[object->state]);
	return;

unsupported_event:
	printk(KERN_ERR "FS-Cache:"
	       " Unsupported event %lx [mask %lx] in state %s\n",
	       object->events, object->event_mask,
	       fscache_object_states[object->state]);
	BUG();
}