1 /* FS-Cache object state machine handler
11  * See Documentation/filesystems/caching/object.txt for a description of the
12  * object state machine and the in-kernel representations.
78  * The object state machine.
117  * In such a situation, object->state remembers the state the machine should
153 static inline void fscache_done_parent_op(struct fscache_object *object)  in fscache_done_parent_op()  argument
155 	struct fscache_object *parent = object->parent;  in fscache_done_parent_op()
158 	       object->debug_id, parent->debug_id, parent->n_ops);  in fscache_done_parent_op()
169  * Object state machine dispatcher.
171 static void fscache_object_sm_dispatcher(struct fscache_object *object)  in fscache_object_sm_dispatcher()  argument
179 	ASSERT(object != NULL);  in fscache_object_sm_dispatcher()
182 	       object->debug_id, object->state->name, object->events);  in fscache_object_sm_dispatcher()
184 	event_mask = object->event_mask;  in fscache_object_sm_dispatcher()
186 	object->event_mask = 0; /* Mask normal event handling */  in fscache_object_sm_dispatcher()
187 	state = object->state;  in fscache_object_sm_dispatcher()
189 	events = object->events;  in fscache_object_sm_dispatcher()
192 	if (events & object->oob_event_mask) {  in fscache_object_sm_dispatcher()
194 		       object->debug_id, events & object->oob_event_mask);  in fscache_object_sm_dispatcher()
196 		for (t = object->oob_table; t->events; t++) {  in fscache_object_sm_dispatcher()
201 				__clear_bit(event, &object->oob_event_mask);  in fscache_object_sm_dispatcher()
202 				clear_bit(event, &object->events);  in fscache_object_sm_dispatcher()
216 					trace_fscache_osm(object, state,  in fscache_object_sm_dispatcher()
218 					clear_bit(event, &object->events);  in fscache_object_sm_dispatcher()
220 					       object->debug_id, event,  in fscache_object_sm_dispatcher()
222 					object->state = state = new_state;  in fscache_object_sm_dispatcher()
235 	_debug("{OBJ%x} exec %s", object->debug_id, state->name);  in fscache_object_sm_dispatcher()
237 	trace_fscache_osm(object, state, false, oob, event);  in fscache_object_sm_dispatcher()
238 	new_state = state->work(object, event);  in fscache_object_sm_dispatcher()
241 		_debug("{OBJ%x} %s notrans", object->debug_id, state->name);  in fscache_object_sm_dispatcher()
246 		fscache_enqueue_object(object);  in fscache_object_sm_dispatcher()
247 		event_mask = object->oob_event_mask;  in fscache_object_sm_dispatcher()
252 	       object->debug_id, state->name, new_state->name);  in fscache_object_sm_dispatcher()
253 	object->state = state = new_state;  in fscache_object_sm_dispatcher()
264 	event_mask = object->oob_event_mask;  in fscache_object_sm_dispatcher()
269 	object->event_mask = event_mask;  in fscache_object_sm_dispatcher()
271 	events = object->events;  in fscache_object_sm_dispatcher()
278  * execute an object
282 	struct fscache_object *object =  in fscache_object_work_func()  local
286 	_enter("{OBJ%x}", object->debug_id);  in fscache_object_work_func()
289 	fscache_object_sm_dispatcher(object);  in fscache_object_work_func()
291 	fscache_put_object(object, fscache_obj_put_work);  in fscache_object_work_func()
295  * fscache_object_init - Initialise a cache object description
296  * @object: Object description
297  * @cookie: Cookie object will be attached to
298  * @cache: Cache in which backing object will be found
300  * Initialise a cache object description to its basic values.
305 void fscache_object_init(struct fscache_object *object,  in fscache_object_init()  argument
313 	object->state = STATE(WAIT_FOR_INIT);  in fscache_object_init()
314 	object->oob_table = fscache_osm_init_oob;  in fscache_object_init()
315 	object->flags = 1 << FSCACHE_OBJECT_IS_LIVE;  in fscache_object_init()
316 	spin_lock_init(&object->lock);  in fscache_object_init()
317 	INIT_LIST_HEAD(&object->cache_link);  in fscache_object_init()
318 	INIT_HLIST_NODE(&object->cookie_link);  in fscache_object_init()
319 	INIT_WORK(&object->work, fscache_object_work_func);  in fscache_object_init()
320 	INIT_LIST_HEAD(&object->dependents);  in fscache_object_init()
321 	INIT_LIST_HEAD(&object->dep_link);  in fscache_object_init()
322 	INIT_LIST_HEAD(&object->pending_ops);  in fscache_object_init()
323 	object->n_children = 0;  in fscache_object_init()
324 	object->n_ops = object->n_in_progress = object->n_exclusive = 0;  in fscache_object_init()
325 	object->events = 0;  in fscache_object_init()
326 	object->store_limit = 0;  in fscache_object_init()
327 	object->store_limit_l = 0;  in fscache_object_init()
328 	object->cache = cache;  in fscache_object_init()
329 	object->cookie = cookie;  in fscache_object_init()
331 	object->parent = NULL;  in fscache_object_init()
333 	RB_CLEAR_NODE(&object->objlist_link);  in fscache_object_init()
336 	object->oob_event_mask = 0;  in fscache_object_init()
337 	for (t = object->oob_table; t->events; t++)  in fscache_object_init()
338 		object->oob_event_mask |= t->events;  in fscache_object_init()
339 	object->event_mask = object->oob_event_mask;  in fscache_object_init()
340 	for (t = object->state->transitions; t->events; t++)  in fscache_object_init()
341 		object->event_mask |= t->events;  in fscache_object_init()
346  * Mark the object as no longer being live, making sure that we synchronise
349 static inline void fscache_mark_object_dead(struct fscache_object *object)  in fscache_mark_object_dead()  argument
351 	spin_lock(&object->lock);  in fscache_mark_object_dead()
352 	clear_bit(FSCACHE_OBJECT_IS_LIVE, &object->flags);  in fscache_mark_object_dead()
353 	spin_unlock(&object->lock);  in fscache_mark_object_dead()
357  * Abort object initialisation before we start it.
359 static const struct fscache_state *fscache_abort_initialisation(struct fscache_object *object,  in fscache_abort_initialisation()  argument
362 	_enter("{OBJ%x},%d", object->debug_id, event);  in fscache_abort_initialisation()
364 	object->oob_event_mask = 0;  in fscache_abort_initialisation()
365 	fscache_dequeue_object(object);  in fscache_abort_initialisation()
370  * initialise an object
371  * - check the specified object's parent to see if we can make use of it
376 static const struct fscache_state *fscache_initialise_object(struct fscache_object *object,  in fscache_initialise_object()  argument
382 	_enter("{OBJ%x},%d", object->debug_id, event);  in fscache_initialise_object()
384 	ASSERT(list_empty(&object->dep_link));  in fscache_initialise_object()
386 	parent = object->parent;  in fscache_initialise_object()
410 	    object->cache->ops->grab_object(object, fscache_obj_get_add_to_deps)) {  in fscache_initialise_object()
411 		list_add(&object->dep_link, &parent->dependents);  in fscache_initialise_object()
429  * Once the parent object is ready, we should kick off our lookup op.
431 static const struct fscache_state *fscache_parent_ready(struct fscache_object *object,  in fscache_parent_ready()  argument
434 	struct fscache_object *parent = object->parent;  in fscache_parent_ready()
436 	_enter("{OBJ%x},%d", object->debug_id, event);  in fscache_parent_ready()
443 	object->lookup_jif = jiffies;  in fscache_parent_ready()
451  * look an object up in the cache from which it was allocated
452  * - we hold an "access lock" on the parent object, so the parent object cannot
455 static const struct fscache_state *fscache_look_up_object(struct fscache_object *object,  in fscache_look_up_object()  argument
458 	struct fscache_cookie *cookie = object->cookie;  in fscache_look_up_object()
459 	struct fscache_object *parent = object->parent;  in fscache_look_up_object()
462 	_enter("{OBJ%x},%d", object->debug_id, event);  in fscache_look_up_object()
464 	object->oob_table = fscache_osm_lookup_oob;  in fscache_look_up_object()
474 	    test_bit(FSCACHE_IOERROR, &object->cache->flags) ||  in fscache_look_up_object()
475 	    !fscache_use_cookie(object)) {  in fscache_look_up_object()
481 	       cookie->def->name, object->cache->tag->name);  in fscache_look_up_object()
485 	ret = object->cache->ops->lookup_object(object);  in fscache_look_up_object()
488 	fscache_unuse_cookie(object);  in fscache_look_up_object()
491 		/* probably stuck behind another object, so move this one to  in fscache_look_up_object()
509  * @object: Object pointing to cookie to mark
512  * existing backing object to continue as there's no data for them to read.
514 void fscache_object_lookup_negative(struct fscache_object *object)  in fscache_object_lookup_negative()  argument
516 	struct fscache_cookie *cookie = object->cookie;  in fscache_object_lookup_negative()
518 	_enter("{OBJ%x,%s}", object->debug_id, object->state->name);  in fscache_object_lookup_negative()
520 	if (!test_and_set_bit(FSCACHE_OBJECT_IS_LOOKED_UP, &object->flags)) {  in fscache_object_lookup_negative()
538  * fscache_obtained_object - Note successful object lookup or creation
539  * @object: Object pointing to cookie to mark
542  * data to a backing object to continue.
544  * Note that after calling this, an object's cookie may be relinquished by the
545  * netfs, and so must be accessed with object lock held.
547 void fscache_obtained_object(struct fscache_object *object)  in fscache_obtained_object()  argument
549 	struct fscache_cookie *cookie = object->cookie;  in fscache_obtained_object()
551 	_enter("{OBJ%x,%s}", object->debug_id, object->state->name);  in fscache_obtained_object()
555 	if (!test_and_set_bit(FSCACHE_OBJECT_IS_LOOKED_UP, &object->flags)) {  in fscache_obtained_object()
571 	set_bit(FSCACHE_OBJECT_IS_AVAILABLE, &object->flags);  in fscache_obtained_object()
577  * handle an object that has just become available
579 static const struct fscache_state *fscache_object_available(struct fscache_object *object,  in fscache_object_available()  argument
582 	_enter("{OBJ%x},%d", object->debug_id, event);  in fscache_object_available()
584 	object->oob_table = fscache_osm_run_oob;  in fscache_object_available()
586 	spin_lock(&object->lock);  in fscache_object_available()
588 	fscache_done_parent_op(object);  in fscache_object_available()
589 	if (object->n_in_progress == 0) {  in fscache_object_available()
590 		if (object->n_ops > 0) {  in fscache_object_available()
591 			ASSERTCMP(object->n_ops, >=, object->n_obj_ops);  in fscache_object_available()
592 			fscache_start_operations(object);  in fscache_object_available()
594 			ASSERT(list_empty(&object->pending_ops));  in fscache_object_available()
597 	spin_unlock(&object->lock);  in fscache_object_available()
600 	object->cache->ops->lookup_complete(object);  in fscache_object_available()
603 	fscache_hist(fscache_obj_instantiate_histogram, object->lookup_jif);  in fscache_object_available()
611  * Wake up this object's dependent objects now that we've become available.
613 static const struct fscache_state *fscache_jumpstart_dependents(struct fscache_object *object,  in fscache_jumpstart_dependents()  argument
616 	_enter("{OBJ%x},%d", object->debug_id, event);  in fscache_jumpstart_dependents()
618 	if (!fscache_enqueue_dependents(object, FSCACHE_OBJECT_EV_PARENT_READY))  in fscache_jumpstart_dependents()
626 static const struct fscache_state *fscache_lookup_failure(struct fscache_object *object,  in fscache_lookup_failure()  argument
631 	_enter("{OBJ%x},%d", object->debug_id, event);  in fscache_lookup_failure()
633 	object->oob_event_mask = 0;  in fscache_lookup_failure()
636 	object->cache->ops->lookup_complete(object);  in fscache_lookup_failure()
639 	set_bit(FSCACHE_OBJECT_KILLED_BY_CACHE, &object->flags);  in fscache_lookup_failure()
641 	cookie = object->cookie;  in fscache_lookup_failure()
646 	fscache_done_parent_op(object);  in fscache_lookup_failure()
651  * Wait for completion of all active operations on this object and the death of
652  * all child objects of this object.
654 static const struct fscache_state *fscache_kill_object(struct fscache_object *object,  in fscache_kill_object()  argument
658 	       object->debug_id, object->n_ops, object->n_children, event);  in fscache_kill_object()
660 	fscache_mark_object_dead(object);  in fscache_kill_object()
661 	object->oob_event_mask = 0;  in fscache_kill_object()
663 	if (test_bit(FSCACHE_OBJECT_RETIRED, &object->flags)) {  in fscache_kill_object()
665 		clear_bit(FSCACHE_OBJECT_PENDING_WRITE, &object->flags);  in fscache_kill_object()
666 		fscache_cancel_all_ops(object);  in fscache_kill_object()
669 	if (list_empty(&object->dependents) &&  in fscache_kill_object()
670 	    object->n_ops == 0 &&  in fscache_kill_object()
671 	    object->n_children == 0)  in fscache_kill_object()
674 	if (object->n_in_progress == 0) {  in fscache_kill_object()
675 		spin_lock(&object->lock);  in fscache_kill_object()
676 		if (object->n_ops > 0 && object->n_in_progress == 0)  in fscache_kill_object()
677 			fscache_start_operations(object);  in fscache_kill_object()
678 		spin_unlock(&object->lock);  in fscache_kill_object()
681 	if (!list_empty(&object->dependents))  in fscache_kill_object()
690 static const struct fscache_state *fscache_kill_dependents(struct fscache_object *object,  in fscache_kill_dependents()  argument
693 	_enter("{OBJ%x},%d", object->debug_id, event);  in fscache_kill_dependents()
695 	if (!fscache_enqueue_dependents(object, FSCACHE_OBJECT_EV_KILL))  in fscache_kill_dependents()
701  * Drop an object's attachments
703 static const struct fscache_state *fscache_drop_object(struct fscache_object *object,  in fscache_drop_object()  argument
706 	struct fscache_object *parent = object->parent;  in fscache_drop_object()
707 	struct fscache_cookie *cookie = object->cookie;  in fscache_drop_object()
708 	struct fscache_cache *cache = object->cache;  in fscache_drop_object()
711 	_enter("{OBJ%x,%d},%d", object->debug_id, object->n_children, event);  in fscache_drop_object()
714 	ASSERT(!hlist_unhashed(&object->cookie_link));  in fscache_drop_object()
718 		fscache_update_aux_data(object);  in fscache_drop_object()
725 	hlist_del_init(&object->cookie_link);  in fscache_drop_object()
740 	spin_lock(&object->lock);  in fscache_drop_object()
741 	spin_unlock(&object->lock);  in fscache_drop_object()
745 	list_del_init(&object->cache_link);  in fscache_drop_object()
749 	cache->ops->drop_object(object);  in fscache_drop_object()
752 	/* The parent object wants to know when all it dependents have gone */  in fscache_drop_object()
762 		object->parent = NULL;  in fscache_drop_object()
765 	/* this just shifts the object release to the work processor */  in fscache_drop_object()
766 	fscache_put_object(object, fscache_obj_put_drop_obj);  in fscache_drop_object()
774  * get a ref on an object
776 static int fscache_get_object(struct fscache_object *object,  in fscache_get_object()  argument
782 	ret = object->cache->ops->grab_object(object, why) ? 0 : -EAGAIN;  in fscache_get_object()
788  * Discard a ref on an object
790 static void fscache_put_object(struct fscache_object *object,  in fscache_put_object()  argument
794 	object->cache->ops->put_object(object, why);  in fscache_put_object()
799  * fscache_object_destroy - Note that a cache object is about to be destroyed
800  * @object: The object to be destroyed
802  * Note the imminent destruction and deallocation of a cache object record.
804 void fscache_object_destroy(struct fscache_object *object)  in fscache_object_destroy()  argument
806 	fscache_objlist_remove(object);  in fscache_object_destroy()
809 	fscache_cookie_put(object->cookie, fscache_cookie_put_object);  in fscache_object_destroy()
810 	object->cookie = NULL;  in fscache_object_destroy()
815  * enqueue an object for metadata-type processing
817 void fscache_enqueue_object(struct fscache_object *object)  in fscache_enqueue_object()  argument
819 	_enter("{OBJ%x}", object->debug_id);  in fscache_enqueue_object()
821 	if (fscache_get_object(object, fscache_obj_get_queue) >= 0) {  in fscache_enqueue_object()
825 		if (queue_work(fscache_object_wq, &object->work)) {  in fscache_enqueue_object()
829 			fscache_put_object(object, fscache_obj_put_queue);  in fscache_enqueue_object()
836  * fscache_object_sleep_till_congested - Sleep until object wq is congested
839  * Allow an object handler to sleep until the object workqueue is congested.
845  * %true is returned if the object wq is congested, %false otherwise.
865  * Enqueue the dependents of an object for metadata-type processing.
871 static bool fscache_enqueue_dependents(struct fscache_object *object, int event)  in fscache_enqueue_dependents()  argument
876 	_enter("{OBJ%x}", object->debug_id);  in fscache_enqueue_dependents()
878 	if (list_empty(&object->dependents))  in fscache_enqueue_dependents()
881 	spin_lock(&object->lock);  in fscache_enqueue_dependents()
883 	while (!list_empty(&object->dependents)) {  in fscache_enqueue_dependents()
884 		dep = list_entry(object->dependents.next,  in fscache_enqueue_dependents()
891 		if (!list_empty(&object->dependents) && need_resched()) {  in fscache_enqueue_dependents()
897 	spin_unlock(&object->lock);  in fscache_enqueue_dependents()
902  * remove an object from whatever queue it's waiting on
904 static void fscache_dequeue_object(struct fscache_object *object)  in fscache_dequeue_object()  argument
906 	_enter("{OBJ%x}", object->debug_id);  in fscache_dequeue_object()
908 	if (!list_empty(&object->dep_link)) {  in fscache_dequeue_object()
909 		spin_lock(&object->parent->lock);  in fscache_dequeue_object()
910 		list_del_init(&object->dep_link);  in fscache_dequeue_object()
911 		spin_unlock(&object->parent->lock);  in fscache_dequeue_object()
918  * fscache_check_aux - Ask the netfs whether an object on disk is still valid
919  * @object: The object to ask about
920  * @data: The auxiliary data for the object
923  * This function consults the netfs about the coherency state of an object.
925  * fscache_look_up_object() on behalf of the cache backend during object lookup
928 enum fscache_checkaux fscache_check_aux(struct fscache_object *object,  in fscache_check_aux()  argument
934 	if (!object->cookie->def->check_aux) {  in fscache_check_aux()
939 	result = object->cookie->def->check_aux(object->cookie->netfs_data,  in fscache_check_aux()
966  * Asynchronously invalidate an object.
968 static const struct fscache_state *_fscache_invalidate_object(struct fscache_object *object,  in _fscache_invalidate_object()  argument
972 	struct fscache_cookie *cookie = object->cookie;  in _fscache_invalidate_object()
974 	_enter("{OBJ%x},%d", object->debug_id, event);  in _fscache_invalidate_object()
977 	 * retire the object instead.  in _fscache_invalidate_object()
979 	if (!fscache_use_cookie(object)) {  in _fscache_invalidate_object()
980 		ASSERT(radix_tree_empty(&object->cookie->stores));  in _fscache_invalidate_object()
981 		set_bit(FSCACHE_OBJECT_RETIRED, &object->flags);  in _fscache_invalidate_object()
988 	clear_bit(FSCACHE_OBJECT_PENDING_WRITE, &object->flags);  in _fscache_invalidate_object()
989 	fscache_cancel_all_ops(object);  in _fscache_invalidate_object()
996 	fscache_operation_init(cookie, op, object->cache->ops->invalidate_object,  in _fscache_invalidate_object()
1004 	if (fscache_submit_exclusive_op(object, op) < 0)  in _fscache_invalidate_object()
1024 	fscache_mark_object_dead(object);  in _fscache_invalidate_object()
1025 	fscache_unuse_cookie(object);  in _fscache_invalidate_object()
1030 	fscache_mark_object_dead(object);  in _fscache_invalidate_object()
1032 	fscache_unuse_cookie(object);  in _fscache_invalidate_object()
1038 static const struct fscache_state *fscache_invalidate_object(struct fscache_object *object,  in fscache_invalidate_object()  argument
1045 	s = _fscache_invalidate_object(object, event);  in fscache_invalidate_object()
1053 static void fscache_update_aux_data(struct fscache_object *object)  in fscache_update_aux_data()  argument
1057 	object->cache->ops->update_object(object);  in fscache_update_aux_data()
1062  * Asynchronously update an object.
1064 static const struct fscache_state *fscache_update_object(struct fscache_object *object,  in fscache_update_object()  argument
1067 	_enter("{OBJ%x},%d", object->debug_id, event);  in fscache_update_object()
1069 	fscache_update_aux_data(object);  in fscache_update_object()
1076  * fscache_object_retrying_stale - Note retrying stale object
1077  * @object: The object that will be retried
1079  * Note that an object lookup found an on-disk object that was adjudged to be
1082 void fscache_object_retrying_stale(struct fscache_object *object)  in fscache_object_retrying_stale()  argument
1089  * fscache_object_mark_killed - Note that an object was killed
1090  * @object: The object that was culled
1091  * @why: The reason the object was killed.
1093  * Note that an object was killed.  Returns true if the object was
1096 void fscache_object_mark_killed(struct fscache_object *object,  in fscache_object_mark_killed()  argument
1099 	if (test_and_set_bit(FSCACHE_OBJECT_KILLED_BY_CACHE, &object->flags)) {  in fscache_object_mark_killed()
1100 		pr_err("Error: Object already killed by cache [%s]\n",  in fscache_object_mark_killed()
1101 		       object->cache->identifier);  in fscache_object_mark_killed()
1123  * The object is dead.  We can get here if an object gets queued by an event
1128 static const struct fscache_state *fscache_object_dead(struct fscache_object *object,  in fscache_object_dead()  argument
1132 			      &object->flags))  in fscache_object_dead()
1135 	WARN(true, "FS-Cache object redispatched after death");  in fscache_object_dead()