1 /* FS-Cache object state machine handler
3 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
4 * Written by David Howells (dhowells@redhat.com)
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License
8 * as published by the Free Software Foundation; either version
9 * 2 of the License, or (at your option) any later version.
11 * See Documentation/filesystems/caching/object.txt for a description of the
12 * object state machine and the in-kernel representations.
15 #define FSCACHE_DEBUG_LEVEL COOKIE
16 #include <linux/module.h>
17 #include <linux/slab.h>
18 #include <linux/prefetch.h>
21 static const struct fscache_state *fscache_abort_initialisation(struct fscache_object *, int);
22 static const struct fscache_state *fscache_kill_dependents(struct fscache_object *, int);
23 static const struct fscache_state *fscache_drop_object(struct fscache_object *, int);
24 static const struct fscache_state *fscache_initialise_object(struct fscache_object *, int);
25 static const struct fscache_state *fscache_invalidate_object(struct fscache_object *, int);
26 static const struct fscache_state *fscache_jumpstart_dependents(struct fscache_object *, int);
27 static const struct fscache_state *fscache_kill_object(struct fscache_object *, int);
28 static const struct fscache_state *fscache_lookup_failure(struct fscache_object *, int);
29 static const struct fscache_state *fscache_look_up_object(struct fscache_object *, int);
30 static const struct fscache_state *fscache_object_available(struct fscache_object *, int);
31 static const struct fscache_state *fscache_parent_ready(struct fscache_object *, int);
32 static const struct fscache_state *fscache_update_object(struct fscache_object *, int);
33 static const struct fscache_state *fscache_object_dead(struct fscache_object *, int);
35 #define __STATE_NAME(n) fscache_osm_##n
36 #define STATE(n) (&__STATE_NAME(n))
39 * Define a work state. Work states are execution states. No event processing
40 * is performed by them. The function attached to a work state returns a
41 * pointer indicating the next state to which the state machine should
42 * transition. Returning NO_TRANSIT repeats the current state, but goes back
43 * to the scheduler first.
45 #define WORK_STATE(n, sn, f) \
46 const struct fscache_state __STATE_NAME(n) = { \
53 * Returns from work states.
55 #define transit_to(state) ({ prefetch(&STATE(state)->work); STATE(state); })
57 #define NO_TRANSIT ((struct fscache_state *)NULL)
60 * Define a wait state. Wait states are event processing states. No execution
61 * is performed by them. Wait states are just tables of "if event X occurs,
62 * clear it and transition to state Y". The dispatcher returns to the
63 * scheduler if none of the events in which the wait state has an interest are
66 #define WAIT_STATE(n, sn, ...) \
67 const struct fscache_state __STATE_NAME(n) = { \
71 .transitions = { __VA_ARGS__, { 0, NULL } } \
74 #define TRANSIT_TO(state, emask) \
75 { .events = (emask), .transit_to = STATE(state) }
78 * The object state machine.
80 static WORK_STATE(INIT_OBJECT, "INIT", fscache_initialise_object);
81 static WORK_STATE(PARENT_READY, "PRDY", fscache_parent_ready);
82 static WORK_STATE(ABORT_INIT, "ABRT", fscache_abort_initialisation);
83 static WORK_STATE(LOOK_UP_OBJECT, "LOOK", fscache_look_up_object);
84 static WORK_STATE(CREATE_OBJECT, "CRTO", fscache_look_up_object);
85 static WORK_STATE(OBJECT_AVAILABLE, "AVBL", fscache_object_available);
86 static WORK_STATE(JUMPSTART_DEPS, "JUMP", fscache_jumpstart_dependents);
88 static WORK_STATE(INVALIDATE_OBJECT, "INVL", fscache_invalidate_object);
89 static WORK_STATE(UPDATE_OBJECT, "UPDT", fscache_update_object);
91 static WORK_STATE(LOOKUP_FAILURE, "LCFL", fscache_lookup_failure);
92 static WORK_STATE(KILL_OBJECT, "KILL", fscache_kill_object);
93 static WORK_STATE(KILL_DEPENDENTS, "KDEP", fscache_kill_dependents);
94 static WORK_STATE(DROP_OBJECT, "DROP", fscache_drop_object);
95 static WORK_STATE(OBJECT_DEAD, "DEAD", fscache_object_dead);
97 static WAIT_STATE(WAIT_FOR_INIT, "?INI",
98 TRANSIT_TO(INIT_OBJECT, 1 << FSCACHE_OBJECT_EV_NEW_CHILD));
100 static WAIT_STATE(WAIT_FOR_PARENT, "?PRN",
101 TRANSIT_TO(PARENT_READY, 1 << FSCACHE_OBJECT_EV_PARENT_READY));
103 static WAIT_STATE(WAIT_FOR_CMD, "?CMD",
104 TRANSIT_TO(INVALIDATE_OBJECT, 1 << FSCACHE_OBJECT_EV_INVALIDATE),
105 TRANSIT_TO(UPDATE_OBJECT, 1 << FSCACHE_OBJECT_EV_UPDATE),
106 TRANSIT_TO(JUMPSTART_DEPS, 1 << FSCACHE_OBJECT_EV_NEW_CHILD));
108 static WAIT_STATE(WAIT_FOR_CLEARANCE, "?CLR",
109 TRANSIT_TO(KILL_OBJECT, 1 << FSCACHE_OBJECT_EV_CLEARED));
112 * Out-of-band event transition tables. These are for handling unexpected
113 * events, such as an I/O error. If an OOB event occurs, the state machine
114 * clears and disables the event and forces a transition to the nominated work
115 * state (acurrently executing work states will complete first).
117 * In such a situation, object->state remembers the state the machine should
118 * have been in/gone to and returning NO_TRANSIT returns to that.
120 static const struct fscache_transition fscache_osm_init_oob[] = {
121 TRANSIT_TO(ABORT_INIT,
122 (1 << FSCACHE_OBJECT_EV_ERROR) |
123 (1 << FSCACHE_OBJECT_EV_KILL)),
127 static const struct fscache_transition fscache_osm_lookup_oob[] = {
128 TRANSIT_TO(LOOKUP_FAILURE,
129 (1 << FSCACHE_OBJECT_EV_ERROR) |
130 (1 << FSCACHE_OBJECT_EV_KILL)),
134 static const struct fscache_transition fscache_osm_run_oob[] = {
135 TRANSIT_TO(KILL_OBJECT,
136 (1 << FSCACHE_OBJECT_EV_ERROR) |
137 (1 << FSCACHE_OBJECT_EV_KILL)),
141 static int fscache_get_object(struct fscache_object *,
142 enum fscache_obj_ref_trace);
143 static void fscache_put_object(struct fscache_object *,
144 enum fscache_obj_ref_trace);
145 static bool fscache_enqueue_dependents(struct fscache_object *, int);
146 static void fscache_dequeue_object(struct fscache_object *);
147 static void fscache_update_aux_data(struct fscache_object *);
150 * we need to notify the parent when an op completes that we had outstanding
153 static inline void fscache_done_parent_op(struct fscache_object *object)
155 struct fscache_object *parent = object->parent;
157 _enter("OBJ%x {OBJ%x,%x}",
158 object->debug_id, parent->debug_id, parent->n_ops);
160 spin_lock_nested(&parent->lock, 1);
163 if (parent->n_ops == 0)
164 fscache_raise_event(parent, FSCACHE_OBJECT_EV_CLEARED);
165 spin_unlock(&parent->lock);
169 * Object state machine dispatcher.
171 static void fscache_object_sm_dispatcher(struct fscache_object *object)
173 const struct fscache_transition *t;
174 const struct fscache_state *state, *new_state;
175 unsigned long events, event_mask;
179 ASSERT(object != NULL);
181 _enter("{OBJ%x,%s,%lx}",
182 object->debug_id, object->state->name, object->events);
184 event_mask = object->event_mask;
186 object->event_mask = 0; /* Mask normal event handling */
187 state = object->state;
189 events = object->events;
191 /* Handle any out-of-band events (typically an error) */
192 if (events & object->oob_event_mask) {
193 _debug("{OBJ%x} oob %lx",
194 object->debug_id, events & object->oob_event_mask);
196 for (t = object->oob_table; t->events; t++) {
197 if (events & t->events) {
198 state = t->transit_to;
199 ASSERT(state->work != NULL);
200 event = fls(events & t->events) - 1;
201 __clear_bit(event, &object->oob_event_mask);
202 clear_bit(event, &object->events);
203 goto execute_work_state;
209 /* Wait states are just transition tables */
211 if (events & event_mask) {
212 for (t = state->transitions; t->events; t++) {
213 if (events & t->events) {
214 new_state = t->transit_to;
215 event = fls(events & t->events) - 1;
216 trace_fscache_osm(object, state,
218 clear_bit(event, &object->events);
219 _debug("{OBJ%x} ev %d: %s -> %s",
220 object->debug_id, event,
221 state->name, new_state->name);
222 object->state = state = new_state;
223 goto execute_work_state;
227 /* The event mask didn't include all the tabled bits */
230 /* Randomly woke up */
235 _debug("{OBJ%x} exec %s", object->debug_id, state->name);
237 trace_fscache_osm(object, state, false, oob, event);
238 new_state = state->work(object, event);
240 if (new_state == NO_TRANSIT) {
241 _debug("{OBJ%x} %s notrans", object->debug_id, state->name);
242 if (unlikely(state == STATE(OBJECT_DEAD))) {
246 fscache_enqueue_object(object);
247 event_mask = object->oob_event_mask;
251 _debug("{OBJ%x} %s -> %s",
252 object->debug_id, state->name, new_state->name);
253 object->state = state = new_state;
256 if (unlikely(state == STATE(OBJECT_DEAD))) {
263 /* Transited to wait state */
264 event_mask = object->oob_event_mask;
265 for (t = state->transitions; t->events; t++)
266 event_mask |= t->events;
269 object->event_mask = event_mask;
271 events = object->events;
272 if (events & event_mask)
274 _leave(" [msk %lx]", event_mask);
280 static void fscache_object_work_func(struct work_struct *work)
282 struct fscache_object *object =
283 container_of(work, struct fscache_object, work);
286 _enter("{OBJ%x}", object->debug_id);
289 fscache_object_sm_dispatcher(object);
290 fscache_hist(fscache_objs_histogram, start);
291 fscache_put_object(object, fscache_obj_put_work);
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.
302 * See Documentation/filesystems/caching/backend-api.txt for a complete
305 void fscache_object_init(struct fscache_object *object,
306 struct fscache_cookie *cookie,
307 struct fscache_cache *cache)
309 const struct fscache_transition *t;
311 atomic_inc(&cache->object_count);
313 object->state = STATE(WAIT_FOR_INIT);
314 object->oob_table = fscache_osm_init_oob;
315 object->flags = 1 << FSCACHE_OBJECT_IS_LIVE;
316 spin_lock_init(&object->lock);
317 INIT_LIST_HEAD(&object->cache_link);
318 INIT_HLIST_NODE(&object->cookie_link);
319 INIT_WORK(&object->work, fscache_object_work_func);
320 INIT_LIST_HEAD(&object->dependents);
321 INIT_LIST_HEAD(&object->dep_link);
322 INIT_LIST_HEAD(&object->pending_ops);
323 object->n_children = 0;
324 object->n_ops = object->n_in_progress = object->n_exclusive = 0;
326 object->store_limit = 0;
327 object->store_limit_l = 0;
328 object->cache = cache;
329 object->cookie = cookie;
330 object->parent = NULL;
331 #ifdef CONFIG_FSCACHE_OBJECT_LIST
332 RB_CLEAR_NODE(&object->objlist_link);
335 object->oob_event_mask = 0;
336 for (t = object->oob_table; t->events; t++)
337 object->oob_event_mask |= t->events;
338 object->event_mask = object->oob_event_mask;
339 for (t = object->state->transitions; t->events; t++)
340 object->event_mask |= t->events;
342 EXPORT_SYMBOL(fscache_object_init);
345 * Mark the object as no longer being live, making sure that we synchronise
346 * against op submission.
348 static inline void fscache_mark_object_dead(struct fscache_object *object)
350 spin_lock(&object->lock);
351 clear_bit(FSCACHE_OBJECT_IS_LIVE, &object->flags);
352 spin_unlock(&object->lock);
356 * Abort object initialisation before we start it.
358 static const struct fscache_state *fscache_abort_initialisation(struct fscache_object *object,
361 _enter("{OBJ%x},%d", object->debug_id, event);
363 object->oob_event_mask = 0;
364 fscache_dequeue_object(object);
365 return transit_to(KILL_OBJECT);
369 * initialise an object
370 * - check the specified object's parent to see if we can make use of it
371 * immediately to do a creation
372 * - we may need to start the process of creating a parent and we need to wait
373 * for the parent's lookup and creation to complete if it's not there yet
375 static const struct fscache_state *fscache_initialise_object(struct fscache_object *object,
378 struct fscache_object *parent;
381 _enter("{OBJ%x},%d", object->debug_id, event);
383 ASSERT(list_empty(&object->dep_link));
385 parent = object->parent;
387 _leave(" [no parent]");
388 return transit_to(DROP_OBJECT);
391 _debug("parent: %s of:%lx", parent->state->name, parent->flags);
393 if (fscache_object_is_dying(parent)) {
394 _leave(" [bad parent]");
395 return transit_to(DROP_OBJECT);
398 if (fscache_object_is_available(parent)) {
400 return transit_to(PARENT_READY);
405 spin_lock(&parent->lock);
406 fscache_stat(&fscache_n_cop_grab_object);
408 if (fscache_object_is_live(parent) &&
409 object->cache->ops->grab_object(object, fscache_obj_get_add_to_deps)) {
410 list_add(&object->dep_link, &parent->dependents);
413 fscache_stat_d(&fscache_n_cop_grab_object);
414 spin_unlock(&parent->lock);
416 _leave(" [grab failed]");
417 return transit_to(DROP_OBJECT);
420 /* fscache_acquire_non_index_cookie() uses this
421 * to wake the chain up */
422 fscache_raise_event(parent, FSCACHE_OBJECT_EV_NEW_CHILD);
424 return transit_to(WAIT_FOR_PARENT);
428 * Once the parent object is ready, we should kick off our lookup op.
430 static const struct fscache_state *fscache_parent_ready(struct fscache_object *object,
433 struct fscache_object *parent = object->parent;
435 _enter("{OBJ%x},%d", object->debug_id, event);
437 ASSERT(parent != NULL);
439 spin_lock(&parent->lock);
442 object->lookup_jif = jiffies;
443 spin_unlock(&parent->lock);
446 return transit_to(LOOK_UP_OBJECT);
450 * look an object up in the cache from which it was allocated
451 * - we hold an "access lock" on the parent object, so the parent object cannot
452 * be withdrawn by either party till we've finished
454 static const struct fscache_state *fscache_look_up_object(struct fscache_object *object,
457 struct fscache_cookie *cookie = object->cookie;
458 struct fscache_object *parent = object->parent;
461 _enter("{OBJ%x},%d", object->debug_id, event);
463 object->oob_table = fscache_osm_lookup_oob;
465 ASSERT(parent != NULL);
466 ASSERTCMP(parent->n_ops, >, 0);
467 ASSERTCMP(parent->n_obj_ops, >, 0);
469 /* make sure the parent is still available */
470 ASSERT(fscache_object_is_available(parent));
472 if (fscache_object_is_dying(parent) ||
473 test_bit(FSCACHE_IOERROR, &object->cache->flags) ||
474 !fscache_use_cookie(object)) {
475 _leave(" [unavailable]");
476 return transit_to(LOOKUP_FAILURE);
479 _debug("LOOKUP \"%s\" in \"%s\"",
480 cookie->def->name, object->cache->tag->name);
482 fscache_stat(&fscache_n_object_lookups);
483 fscache_stat(&fscache_n_cop_lookup_object);
484 ret = object->cache->ops->lookup_object(object);
485 fscache_stat_d(&fscache_n_cop_lookup_object);
487 fscache_unuse_cookie(object);
489 if (ret == -ETIMEDOUT) {
490 /* probably stuck behind another object, so move this one to
491 * the back of the queue */
492 fscache_stat(&fscache_n_object_lookups_timed_out);
493 _leave(" [timeout]");
499 return transit_to(LOOKUP_FAILURE);
503 return transit_to(OBJECT_AVAILABLE);
507 * fscache_object_lookup_negative - Note negative cookie lookup
508 * @object: Object pointing to cookie to mark
510 * Note negative lookup, permitting those waiting to read data from an already
511 * existing backing object to continue as there's no data for them to read.
513 void fscache_object_lookup_negative(struct fscache_object *object)
515 struct fscache_cookie *cookie = object->cookie;
517 _enter("{OBJ%x,%s}", object->debug_id, object->state->name);
519 if (!test_and_set_bit(FSCACHE_OBJECT_IS_LOOKED_UP, &object->flags)) {
520 fscache_stat(&fscache_n_object_lookups_negative);
522 /* Allow write requests to begin stacking up and read requests to begin
525 set_bit(FSCACHE_COOKIE_NO_DATA_YET, &cookie->flags);
526 clear_bit(FSCACHE_COOKIE_UNAVAILABLE, &cookie->flags);
528 _debug("wake up lookup %p", &cookie->flags);
529 clear_bit_unlock(FSCACHE_COOKIE_LOOKING_UP, &cookie->flags);
530 wake_up_bit(&cookie->flags, FSCACHE_COOKIE_LOOKING_UP);
534 EXPORT_SYMBOL(fscache_object_lookup_negative);
537 * fscache_obtained_object - Note successful object lookup or creation
538 * @object: Object pointing to cookie to mark
540 * Note successful lookup and/or creation, permitting those waiting to write
541 * data to a backing object to continue.
543 * Note that after calling this, an object's cookie may be relinquished by the
544 * netfs, and so must be accessed with object lock held.
546 void fscache_obtained_object(struct fscache_object *object)
548 struct fscache_cookie *cookie = object->cookie;
550 _enter("{OBJ%x,%s}", object->debug_id, object->state->name);
552 /* if we were still looking up, then we must have a positive lookup
553 * result, in which case there may be data available */
554 if (!test_and_set_bit(FSCACHE_OBJECT_IS_LOOKED_UP, &object->flags)) {
555 fscache_stat(&fscache_n_object_lookups_positive);
557 /* We do (presumably) have data */
558 clear_bit_unlock(FSCACHE_COOKIE_NO_DATA_YET, &cookie->flags);
559 clear_bit(FSCACHE_COOKIE_UNAVAILABLE, &cookie->flags);
561 /* Allow write requests to begin stacking up and read requests
562 * to begin shovelling data.
564 clear_bit_unlock(FSCACHE_COOKIE_LOOKING_UP, &cookie->flags);
565 wake_up_bit(&cookie->flags, FSCACHE_COOKIE_LOOKING_UP);
567 fscache_stat(&fscache_n_object_created);
570 set_bit(FSCACHE_OBJECT_IS_AVAILABLE, &object->flags);
573 EXPORT_SYMBOL(fscache_obtained_object);
576 * handle an object that has just become available
578 static const struct fscache_state *fscache_object_available(struct fscache_object *object,
581 _enter("{OBJ%x},%d", object->debug_id, event);
583 object->oob_table = fscache_osm_run_oob;
585 spin_lock(&object->lock);
587 fscache_done_parent_op(object);
588 if (object->n_in_progress == 0) {
589 if (object->n_ops > 0) {
590 ASSERTCMP(object->n_ops, >=, object->n_obj_ops);
591 fscache_start_operations(object);
593 ASSERT(list_empty(&object->pending_ops));
596 spin_unlock(&object->lock);
598 fscache_stat(&fscache_n_cop_lookup_complete);
599 object->cache->ops->lookup_complete(object);
600 fscache_stat_d(&fscache_n_cop_lookup_complete);
602 fscache_hist(fscache_obj_instantiate_histogram, object->lookup_jif);
603 fscache_stat(&fscache_n_object_avail);
606 return transit_to(JUMPSTART_DEPS);
610 * Wake up this object's dependent objects now that we've become available.
612 static const struct fscache_state *fscache_jumpstart_dependents(struct fscache_object *object,
615 _enter("{OBJ%x},%d", object->debug_id, event);
617 if (!fscache_enqueue_dependents(object, FSCACHE_OBJECT_EV_PARENT_READY))
618 return NO_TRANSIT; /* Not finished; requeue */
619 return transit_to(WAIT_FOR_CMD);
623 * Handle lookup or creation failute.
625 static const struct fscache_state *fscache_lookup_failure(struct fscache_object *object,
628 struct fscache_cookie *cookie;
630 _enter("{OBJ%x},%d", object->debug_id, event);
632 object->oob_event_mask = 0;
634 fscache_stat(&fscache_n_cop_lookup_complete);
635 object->cache->ops->lookup_complete(object);
636 fscache_stat_d(&fscache_n_cop_lookup_complete);
638 set_bit(FSCACHE_OBJECT_KILLED_BY_CACHE, &object->flags);
640 cookie = object->cookie;
641 set_bit(FSCACHE_COOKIE_UNAVAILABLE, &cookie->flags);
642 if (test_and_clear_bit(FSCACHE_COOKIE_LOOKING_UP, &cookie->flags))
643 wake_up_bit(&cookie->flags, FSCACHE_COOKIE_LOOKING_UP);
645 fscache_done_parent_op(object);
646 return transit_to(KILL_OBJECT);
650 * Wait for completion of all active operations on this object and the death of
651 * all child objects of this object.
653 static const struct fscache_state *fscache_kill_object(struct fscache_object *object,
656 _enter("{OBJ%x,%d,%d},%d",
657 object->debug_id, object->n_ops, object->n_children, event);
659 fscache_mark_object_dead(object);
660 object->oob_event_mask = 0;
662 if (test_bit(FSCACHE_OBJECT_RETIRED, &object->flags)) {
663 /* Reject any new read/write ops and abort any that are pending. */
664 clear_bit(FSCACHE_OBJECT_PENDING_WRITE, &object->flags);
665 fscache_cancel_all_ops(object);
668 if (list_empty(&object->dependents) &&
669 object->n_ops == 0 &&
670 object->n_children == 0)
671 return transit_to(DROP_OBJECT);
673 if (object->n_in_progress == 0) {
674 spin_lock(&object->lock);
675 if (object->n_ops > 0 && object->n_in_progress == 0)
676 fscache_start_operations(object);
677 spin_unlock(&object->lock);
680 if (!list_empty(&object->dependents))
681 return transit_to(KILL_DEPENDENTS);
683 return transit_to(WAIT_FOR_CLEARANCE);
687 * Kill dependent objects.
689 static const struct fscache_state *fscache_kill_dependents(struct fscache_object *object,
692 _enter("{OBJ%x},%d", object->debug_id, event);
694 if (!fscache_enqueue_dependents(object, FSCACHE_OBJECT_EV_KILL))
695 return NO_TRANSIT; /* Not finished */
696 return transit_to(WAIT_FOR_CLEARANCE);
700 * Drop an object's attachments
702 static const struct fscache_state *fscache_drop_object(struct fscache_object *object,
705 struct fscache_object *parent = object->parent;
706 struct fscache_cookie *cookie = object->cookie;
707 struct fscache_cache *cache = object->cache;
710 _enter("{OBJ%x,%d},%d", object->debug_id, object->n_children, event);
712 ASSERT(cookie != NULL);
713 ASSERT(!hlist_unhashed(&object->cookie_link));
715 if (test_bit(FSCACHE_COOKIE_AUX_UPDATED, &cookie->flags)) {
716 _debug("final update");
717 fscache_update_aux_data(object);
720 /* Make sure the cookie no longer points here and that the netfs isn't
723 spin_lock(&cookie->lock);
724 hlist_del_init(&object->cookie_link);
725 if (hlist_empty(&cookie->backing_objects) &&
726 test_and_clear_bit(FSCACHE_COOKIE_INVALIDATING, &cookie->flags))
728 spin_unlock(&cookie->lock);
731 wake_up_bit(&cookie->flags, FSCACHE_COOKIE_INVALIDATING);
733 /* Prevent a race with our last child, which has to signal EV_CLEARED
734 * before dropping our spinlock.
736 spin_lock(&object->lock);
737 spin_unlock(&object->lock);
739 /* Discard from the cache's collection of objects */
740 spin_lock(&cache->object_list_lock);
741 list_del_init(&object->cache_link);
742 spin_unlock(&cache->object_list_lock);
744 fscache_stat(&fscache_n_cop_drop_object);
745 cache->ops->drop_object(object);
746 fscache_stat_d(&fscache_n_cop_drop_object);
748 /* The parent object wants to know when all it dependents have gone */
750 _debug("release parent OBJ%x {%d}",
751 parent->debug_id, parent->n_children);
753 spin_lock(&parent->lock);
754 parent->n_children--;
755 if (parent->n_children == 0)
756 fscache_raise_event(parent, FSCACHE_OBJECT_EV_CLEARED);
757 spin_unlock(&parent->lock);
758 object->parent = NULL;
761 /* this just shifts the object release to the work processor */
762 fscache_put_object(object, fscache_obj_put_drop_obj);
763 fscache_stat(&fscache_n_object_dead);
766 return transit_to(OBJECT_DEAD);
770 * get a ref on an object
772 static int fscache_get_object(struct fscache_object *object,
773 enum fscache_obj_ref_trace why)
777 fscache_stat(&fscache_n_cop_grab_object);
778 ret = object->cache->ops->grab_object(object, why) ? 0 : -EAGAIN;
779 fscache_stat_d(&fscache_n_cop_grab_object);
784 * Discard a ref on an object
786 static void fscache_put_object(struct fscache_object *object,
787 enum fscache_obj_ref_trace why)
789 fscache_stat(&fscache_n_cop_put_object);
790 object->cache->ops->put_object(object, why);
791 fscache_stat_d(&fscache_n_cop_put_object);
795 * fscache_object_destroy - Note that a cache object is about to be destroyed
796 * @object: The object to be destroyed
798 * Note the imminent destruction and deallocation of a cache object record.
800 void fscache_object_destroy(struct fscache_object *object)
802 fscache_objlist_remove(object);
804 /* We can get rid of the cookie now */
805 fscache_cookie_put(object->cookie, fscache_cookie_put_object);
806 object->cookie = NULL;
808 EXPORT_SYMBOL(fscache_object_destroy);
811 * enqueue an object for metadata-type processing
813 void fscache_enqueue_object(struct fscache_object *object)
815 _enter("{OBJ%x}", object->debug_id);
817 if (fscache_get_object(object, fscache_obj_get_queue) >= 0) {
818 wait_queue_head_t *cong_wq =
819 &get_cpu_var(fscache_object_cong_wait);
821 if (queue_work(fscache_object_wq, &object->work)) {
822 if (fscache_object_congested())
825 fscache_put_object(object, fscache_obj_put_queue);
827 put_cpu_var(fscache_object_cong_wait);
832 * fscache_object_sleep_till_congested - Sleep until object wq is congested
833 * @timeoutp: Scheduler sleep timeout
835 * Allow an object handler to sleep until the object workqueue is congested.
837 * The caller must set up a wake up event before calling this and must have set
838 * the appropriate sleep mode (such as TASK_UNINTERRUPTIBLE) and tested its own
839 * condition before calling this function as no test is made here.
841 * %true is returned if the object wq is congested, %false otherwise.
843 bool fscache_object_sleep_till_congested(signed long *timeoutp)
845 wait_queue_head_t *cong_wq = this_cpu_ptr(&fscache_object_cong_wait);
848 if (fscache_object_congested())
851 add_wait_queue_exclusive(cong_wq, &wait);
852 if (!fscache_object_congested())
853 *timeoutp = schedule_timeout(*timeoutp);
854 finish_wait(cong_wq, &wait);
856 return fscache_object_congested();
858 EXPORT_SYMBOL_GPL(fscache_object_sleep_till_congested);
861 * Enqueue the dependents of an object for metadata-type processing.
863 * If we don't manage to finish the list before the scheduler wants to run
864 * again then return false immediately. We return true if the list was
867 static bool fscache_enqueue_dependents(struct fscache_object *object, int event)
869 struct fscache_object *dep;
872 _enter("{OBJ%x}", object->debug_id);
874 if (list_empty(&object->dependents))
877 spin_lock(&object->lock);
879 while (!list_empty(&object->dependents)) {
880 dep = list_entry(object->dependents.next,
881 struct fscache_object, dep_link);
882 list_del_init(&dep->dep_link);
884 fscache_raise_event(dep, event);
885 fscache_put_object(dep, fscache_obj_put_enq_dep);
887 if (!list_empty(&object->dependents) && need_resched()) {
893 spin_unlock(&object->lock);
898 * remove an object from whatever queue it's waiting on
900 static void fscache_dequeue_object(struct fscache_object *object)
902 _enter("{OBJ%x}", object->debug_id);
904 if (!list_empty(&object->dep_link)) {
905 spin_lock(&object->parent->lock);
906 list_del_init(&object->dep_link);
907 spin_unlock(&object->parent->lock);
914 * fscache_check_aux - Ask the netfs whether an object on disk is still valid
915 * @object: The object to ask about
916 * @data: The auxiliary data for the object
917 * @datalen: The size of the auxiliary data
919 * This function consults the netfs about the coherency state of an object.
920 * The caller must be holding a ref on cookie->n_active (held by
921 * fscache_look_up_object() on behalf of the cache backend during object lookup
924 enum fscache_checkaux fscache_check_aux(struct fscache_object *object,
925 const void *data, uint16_t datalen,
928 enum fscache_checkaux result;
930 if (!object->cookie->def->check_aux) {
931 fscache_stat(&fscache_n_checkaux_none);
932 return FSCACHE_CHECKAUX_OKAY;
935 result = object->cookie->def->check_aux(object->cookie->netfs_data,
936 data, datalen, object_size);
938 /* entry okay as is */
939 case FSCACHE_CHECKAUX_OKAY:
940 fscache_stat(&fscache_n_checkaux_okay);
943 /* entry requires update */
944 case FSCACHE_CHECKAUX_NEEDS_UPDATE:
945 fscache_stat(&fscache_n_checkaux_update);
948 /* entry requires deletion */
949 case FSCACHE_CHECKAUX_OBSOLETE:
950 fscache_stat(&fscache_n_checkaux_obsolete);
959 EXPORT_SYMBOL(fscache_check_aux);
962 * Asynchronously invalidate an object.
964 static const struct fscache_state *_fscache_invalidate_object(struct fscache_object *object,
967 struct fscache_operation *op;
968 struct fscache_cookie *cookie = object->cookie;
970 _enter("{OBJ%x},%d", object->debug_id, event);
972 /* We're going to need the cookie. If the cookie is not available then
973 * retire the object instead.
975 if (!fscache_use_cookie(object)) {
976 ASSERT(radix_tree_empty(&object->cookie->stores));
977 set_bit(FSCACHE_OBJECT_RETIRED, &object->flags);
978 _leave(" [no cookie]");
979 return transit_to(KILL_OBJECT);
982 /* Reject any new read/write ops and abort any that are pending. */
983 fscache_invalidate_writes(cookie);
984 clear_bit(FSCACHE_OBJECT_PENDING_WRITE, &object->flags);
985 fscache_cancel_all_ops(object);
987 /* Now we have to wait for in-progress reads and writes */
988 op = kzalloc(sizeof(*op), GFP_KERNEL);
992 fscache_operation_init(cookie, op, object->cache->ops->invalidate_object,
994 op->flags = FSCACHE_OP_ASYNC |
995 (1 << FSCACHE_OP_EXCLUSIVE) |
996 (1 << FSCACHE_OP_UNUSE_COOKIE);
997 trace_fscache_page_op(cookie, NULL, op, fscache_page_op_invalidate);
999 spin_lock(&cookie->lock);
1000 if (fscache_submit_exclusive_op(object, op) < 0)
1001 goto submit_op_failed;
1002 spin_unlock(&cookie->lock);
1003 fscache_put_operation(op);
1005 /* Once we've completed the invalidation, we know there will be no data
1006 * stored in the cache and thus we can reinstate the data-check-skip
1009 set_bit(FSCACHE_COOKIE_NO_DATA_YET, &cookie->flags);
1011 /* We can allow read and write requests to come in once again. They'll
1012 * queue up behind our exclusive invalidation operation.
1014 if (test_and_clear_bit(FSCACHE_COOKIE_INVALIDATING, &cookie->flags))
1015 wake_up_bit(&cookie->flags, FSCACHE_COOKIE_INVALIDATING);
1017 return transit_to(UPDATE_OBJECT);
1020 fscache_mark_object_dead(object);
1021 fscache_unuse_cookie(object);
1022 _leave(" [ENOMEM]");
1023 return transit_to(KILL_OBJECT);
1026 fscache_mark_object_dead(object);
1027 spin_unlock(&cookie->lock);
1028 fscache_unuse_cookie(object);
1031 return transit_to(KILL_OBJECT);
1034 static const struct fscache_state *fscache_invalidate_object(struct fscache_object *object,
1037 const struct fscache_state *s;
1039 fscache_stat(&fscache_n_invalidates_run);
1040 fscache_stat(&fscache_n_cop_invalidate_object);
1041 s = _fscache_invalidate_object(object, event);
1042 fscache_stat_d(&fscache_n_cop_invalidate_object);
1047 * Update auxiliary data.
1049 static void fscache_update_aux_data(struct fscache_object *object)
1051 fscache_stat(&fscache_n_updates_run);
1052 fscache_stat(&fscache_n_cop_update_object);
1053 object->cache->ops->update_object(object);
1054 fscache_stat_d(&fscache_n_cop_update_object);
1058 * Asynchronously update an object.
1060 static const struct fscache_state *fscache_update_object(struct fscache_object *object,
1063 _enter("{OBJ%x},%d", object->debug_id, event);
1065 fscache_update_aux_data(object);
1068 return transit_to(WAIT_FOR_CMD);
1072 * fscache_object_retrying_stale - Note retrying stale object
1073 * @object: The object that will be retried
1075 * Note that an object lookup found an on-disk object that was adjudged to be
1076 * stale and has been deleted. The lookup will be retried.
1078 void fscache_object_retrying_stale(struct fscache_object *object)
1080 fscache_stat(&fscache_n_cache_no_space_reject);
1082 EXPORT_SYMBOL(fscache_object_retrying_stale);
1085 * fscache_object_mark_killed - Note that an object was killed
1086 * @object: The object that was culled
1087 * @why: The reason the object was killed.
1089 * Note that an object was killed. Returns true if the object was
1090 * already marked killed, false if it wasn't.
1092 void fscache_object_mark_killed(struct fscache_object *object,
1093 enum fscache_why_object_killed why)
1095 if (test_and_set_bit(FSCACHE_OBJECT_KILLED_BY_CACHE, &object->flags)) {
1096 pr_err("Error: Object already killed by cache [%s]\n",
1097 object->cache->identifier);
1102 case FSCACHE_OBJECT_NO_SPACE:
1103 fscache_stat(&fscache_n_cache_no_space_reject);
1105 case FSCACHE_OBJECT_IS_STALE:
1106 fscache_stat(&fscache_n_cache_stale_objects);
1108 case FSCACHE_OBJECT_WAS_RETIRED:
1109 fscache_stat(&fscache_n_cache_retired_objects);
1111 case FSCACHE_OBJECT_WAS_CULLED:
1112 fscache_stat(&fscache_n_cache_culled_objects);
1116 EXPORT_SYMBOL(fscache_object_mark_killed);
1119 * The object is dead. We can get here if an object gets queued by an event
1120 * that would lead to its death (such as EV_KILL) when the dispatcher is
1121 * already running (and so can be requeued) but hasn't yet cleared the event
1124 static const struct fscache_state *fscache_object_dead(struct fscache_object *object,
1127 if (!test_and_set_bit(FSCACHE_OBJECT_RUN_AFTER_DEAD,
1131 WARN(true, "FS-Cache object redispatched after death");