1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* FS-Cache object state machine handler
4 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells (dhowells@redhat.com)
7 * See Documentation/filesystems/caching/object.rst for a description of the
8 * object state machine and the in-kernel representations.
11 #define FSCACHE_DEBUG_LEVEL COOKIE
12 #include <linux/module.h>
13 #include <linux/slab.h>
14 #include <linux/prefetch.h>
17 static const struct fscache_state
*fscache_abort_initialisation(struct fscache_object
*, int);
18 static const struct fscache_state
*fscache_kill_dependents(struct fscache_object
*, int);
19 static const struct fscache_state
*fscache_drop_object(struct fscache_object
*, int);
20 static const struct fscache_state
*fscache_initialise_object(struct fscache_object
*, int);
21 static const struct fscache_state
*fscache_invalidate_object(struct fscache_object
*, int);
22 static const struct fscache_state
*fscache_jumpstart_dependents(struct fscache_object
*, int);
23 static const struct fscache_state
*fscache_kill_object(struct fscache_object
*, int);
24 static const struct fscache_state
*fscache_lookup_failure(struct fscache_object
*, int);
25 static const struct fscache_state
*fscache_look_up_object(struct fscache_object
*, int);
26 static const struct fscache_state
*fscache_object_available(struct fscache_object
*, int);
27 static const struct fscache_state
*fscache_parent_ready(struct fscache_object
*, int);
28 static const struct fscache_state
*fscache_update_object(struct fscache_object
*, int);
29 static const struct fscache_state
*fscache_object_dead(struct fscache_object
*, int);
31 #define __STATE_NAME(n) fscache_osm_##n
32 #define STATE(n) (&__STATE_NAME(n))
35 * Define a work state. Work states are execution states. No event processing
36 * is performed by them. The function attached to a work state returns a
37 * pointer indicating the next state to which the state machine should
38 * transition. Returning NO_TRANSIT repeats the current state, but goes back
39 * to the scheduler first.
41 #define WORK_STATE(n, sn, f) \
42 const struct fscache_state __STATE_NAME(n) = { \
49 * Returns from work states.
51 #define transit_to(state) ({ prefetch(&STATE(state)->work); STATE(state); })
53 #define NO_TRANSIT ((struct fscache_state *)NULL)
56 * Define a wait state. Wait states are event processing states. No execution
57 * is performed by them. Wait states are just tables of "if event X occurs,
58 * clear it and transition to state Y". The dispatcher returns to the
59 * scheduler if none of the events in which the wait state has an interest are
62 #define WAIT_STATE(n, sn, ...) \
63 const struct fscache_state __STATE_NAME(n) = { \
67 .transitions = { __VA_ARGS__, { 0, NULL } } \
70 #define TRANSIT_TO(state, emask) \
71 { .events = (emask), .transit_to = STATE(state) }
74 * The object state machine.
76 static WORK_STATE(INIT_OBJECT
, "INIT", fscache_initialise_object
);
77 static WORK_STATE(PARENT_READY
, "PRDY", fscache_parent_ready
);
78 static WORK_STATE(ABORT_INIT
, "ABRT", fscache_abort_initialisation
);
79 static WORK_STATE(LOOK_UP_OBJECT
, "LOOK", fscache_look_up_object
);
80 static WORK_STATE(OBJECT_AVAILABLE
, "AVBL", fscache_object_available
);
81 static WORK_STATE(JUMPSTART_DEPS
, "JUMP", fscache_jumpstart_dependents
);
83 static WORK_STATE(INVALIDATE_OBJECT
, "INVL", fscache_invalidate_object
);
84 static WORK_STATE(UPDATE_OBJECT
, "UPDT", fscache_update_object
);
86 static WORK_STATE(LOOKUP_FAILURE
, "LCFL", fscache_lookup_failure
);
87 static WORK_STATE(KILL_OBJECT
, "KILL", fscache_kill_object
);
88 static WORK_STATE(KILL_DEPENDENTS
, "KDEP", fscache_kill_dependents
);
89 static WORK_STATE(DROP_OBJECT
, "DROP", fscache_drop_object
);
90 static WORK_STATE(OBJECT_DEAD
, "DEAD", fscache_object_dead
);
92 static WAIT_STATE(WAIT_FOR_INIT
, "?INI",
93 TRANSIT_TO(INIT_OBJECT
, 1 << FSCACHE_OBJECT_EV_NEW_CHILD
));
95 static WAIT_STATE(WAIT_FOR_PARENT
, "?PRN",
96 TRANSIT_TO(PARENT_READY
, 1 << FSCACHE_OBJECT_EV_PARENT_READY
));
98 static WAIT_STATE(WAIT_FOR_CMD
, "?CMD",
99 TRANSIT_TO(INVALIDATE_OBJECT
, 1 << FSCACHE_OBJECT_EV_INVALIDATE
),
100 TRANSIT_TO(UPDATE_OBJECT
, 1 << FSCACHE_OBJECT_EV_UPDATE
),
101 TRANSIT_TO(JUMPSTART_DEPS
, 1 << FSCACHE_OBJECT_EV_NEW_CHILD
));
103 static WAIT_STATE(WAIT_FOR_CLEARANCE
, "?CLR",
104 TRANSIT_TO(KILL_OBJECT
, 1 << FSCACHE_OBJECT_EV_CLEARED
));
107 * Out-of-band event transition tables. These are for handling unexpected
108 * events, such as an I/O error. If an OOB event occurs, the state machine
109 * clears and disables the event and forces a transition to the nominated work
110 * state (acurrently executing work states will complete first).
112 * In such a situation, object->state remembers the state the machine should
113 * have been in/gone to and returning NO_TRANSIT returns to that.
115 static const struct fscache_transition fscache_osm_init_oob
[] = {
116 TRANSIT_TO(ABORT_INIT
,
117 (1 << FSCACHE_OBJECT_EV_ERROR
) |
118 (1 << FSCACHE_OBJECT_EV_KILL
)),
122 static const struct fscache_transition fscache_osm_lookup_oob
[] = {
123 TRANSIT_TO(LOOKUP_FAILURE
,
124 (1 << FSCACHE_OBJECT_EV_ERROR
) |
125 (1 << FSCACHE_OBJECT_EV_KILL
)),
129 static const struct fscache_transition fscache_osm_run_oob
[] = {
130 TRANSIT_TO(KILL_OBJECT
,
131 (1 << FSCACHE_OBJECT_EV_ERROR
) |
132 (1 << FSCACHE_OBJECT_EV_KILL
)),
136 static int fscache_get_object(struct fscache_object
*,
137 enum fscache_obj_ref_trace
);
138 static void fscache_put_object(struct fscache_object
*,
139 enum fscache_obj_ref_trace
);
140 static bool fscache_enqueue_dependents(struct fscache_object
*, int);
141 static void fscache_dequeue_object(struct fscache_object
*);
142 static void fscache_update_aux_data(struct fscache_object
*);
145 * we need to notify the parent when an op completes that we had outstanding
148 static inline void fscache_done_parent_op(struct fscache_object
*object
)
150 struct fscache_object
*parent
= object
->parent
;
152 _enter("OBJ%x {OBJ%x,%x}",
153 object
->debug_id
, parent
->debug_id
, parent
->n_ops
);
155 spin_lock_nested(&parent
->lock
, 1);
158 if (parent
->n_ops
== 0)
159 fscache_raise_event(parent
, FSCACHE_OBJECT_EV_CLEARED
);
160 spin_unlock(&parent
->lock
);
164 * Object state machine dispatcher.
166 static void fscache_object_sm_dispatcher(struct fscache_object
*object
)
168 const struct fscache_transition
*t
;
169 const struct fscache_state
*state
, *new_state
;
170 unsigned long events
, event_mask
;
174 ASSERT(object
!= NULL
);
176 _enter("{OBJ%x,%s,%lx}",
177 object
->debug_id
, object
->state
->name
, object
->events
);
179 event_mask
= object
->event_mask
;
181 object
->event_mask
= 0; /* Mask normal event handling */
182 state
= object
->state
;
184 events
= object
->events
;
186 /* Handle any out-of-band events (typically an error) */
187 if (events
& object
->oob_event_mask
) {
188 _debug("{OBJ%x} oob %lx",
189 object
->debug_id
, events
& object
->oob_event_mask
);
191 for (t
= object
->oob_table
; t
->events
; t
++) {
192 if (events
& t
->events
) {
193 state
= t
->transit_to
;
194 ASSERT(state
->work
!= NULL
);
195 event
= fls(events
& t
->events
) - 1;
196 __clear_bit(event
, &object
->oob_event_mask
);
197 clear_bit(event
, &object
->events
);
198 goto execute_work_state
;
204 /* Wait states are just transition tables */
206 if (events
& event_mask
) {
207 for (t
= state
->transitions
; t
->events
; t
++) {
208 if (events
& t
->events
) {
209 new_state
= t
->transit_to
;
210 event
= fls(events
& t
->events
) - 1;
211 trace_fscache_osm(object
, state
,
213 clear_bit(event
, &object
->events
);
214 _debug("{OBJ%x} ev %d: %s -> %s",
215 object
->debug_id
, event
,
216 state
->name
, new_state
->name
);
217 object
->state
= state
= new_state
;
218 goto execute_work_state
;
222 /* The event mask didn't include all the tabled bits */
225 /* Randomly woke up */
230 _debug("{OBJ%x} exec %s", object
->debug_id
, state
->name
);
232 trace_fscache_osm(object
, state
, false, oob
, event
);
233 new_state
= state
->work(object
, event
);
235 if (new_state
== NO_TRANSIT
) {
236 _debug("{OBJ%x} %s notrans", object
->debug_id
, state
->name
);
237 if (unlikely(state
== STATE(OBJECT_DEAD
))) {
241 fscache_enqueue_object(object
);
242 event_mask
= object
->oob_event_mask
;
246 _debug("{OBJ%x} %s -> %s",
247 object
->debug_id
, state
->name
, new_state
->name
);
248 object
->state
= state
= new_state
;
251 if (unlikely(state
== STATE(OBJECT_DEAD
))) {
258 /* Transited to wait state */
259 event_mask
= object
->oob_event_mask
;
260 for (t
= state
->transitions
; t
->events
; t
++)
261 event_mask
|= t
->events
;
264 object
->event_mask
= event_mask
;
266 events
= object
->events
;
267 if (events
& event_mask
)
269 _leave(" [msk %lx]", event_mask
);
275 static void fscache_object_work_func(struct work_struct
*work
)
277 struct fscache_object
*object
=
278 container_of(work
, struct fscache_object
, work
);
280 _enter("{OBJ%x}", object
->debug_id
);
282 fscache_object_sm_dispatcher(object
);
283 fscache_put_object(object
, fscache_obj_put_work
);
287 * fscache_object_init - Initialise a cache object description
288 * @object: Object description
289 * @cookie: Cookie object will be attached to
290 * @cache: Cache in which backing object will be found
292 * Initialise a cache object description to its basic values.
294 * See Documentation/filesystems/caching/backend-api.rst for a complete
297 void fscache_object_init(struct fscache_object
*object
,
298 struct fscache_cookie
*cookie
,
299 struct fscache_cache
*cache
)
301 const struct fscache_transition
*t
;
303 atomic_inc(&cache
->object_count
);
305 object
->state
= STATE(WAIT_FOR_INIT
);
306 object
->oob_table
= fscache_osm_init_oob
;
307 object
->flags
= 1 << FSCACHE_OBJECT_IS_LIVE
;
308 spin_lock_init(&object
->lock
);
309 INIT_LIST_HEAD(&object
->cache_link
);
310 INIT_HLIST_NODE(&object
->cookie_link
);
311 INIT_WORK(&object
->work
, fscache_object_work_func
);
312 INIT_LIST_HEAD(&object
->dependents
);
313 INIT_LIST_HEAD(&object
->dep_link
);
314 INIT_LIST_HEAD(&object
->pending_ops
);
315 object
->n_children
= 0;
316 object
->n_ops
= object
->n_in_progress
= object
->n_exclusive
= 0;
318 object
->store_limit
= 0;
319 object
->store_limit_l
= 0;
320 object
->cache
= cache
;
321 object
->cookie
= cookie
;
322 fscache_cookie_get(cookie
, fscache_cookie_get_attach_object
);
323 object
->parent
= NULL
;
324 #ifdef CONFIG_FSCACHE_OBJECT_LIST
325 RB_CLEAR_NODE(&object
->objlist_link
);
328 object
->oob_event_mask
= 0;
329 for (t
= object
->oob_table
; t
->events
; t
++)
330 object
->oob_event_mask
|= t
->events
;
331 object
->event_mask
= object
->oob_event_mask
;
332 for (t
= object
->state
->transitions
; t
->events
; t
++)
333 object
->event_mask
|= t
->events
;
335 EXPORT_SYMBOL(fscache_object_init
);
338 * Mark the object as no longer being live, making sure that we synchronise
339 * against op submission.
341 static inline void fscache_mark_object_dead(struct fscache_object
*object
)
343 spin_lock(&object
->lock
);
344 clear_bit(FSCACHE_OBJECT_IS_LIVE
, &object
->flags
);
345 spin_unlock(&object
->lock
);
349 * Abort object initialisation before we start it.
351 static const struct fscache_state
*fscache_abort_initialisation(struct fscache_object
*object
,
354 _enter("{OBJ%x},%d", object
->debug_id
, event
);
356 object
->oob_event_mask
= 0;
357 fscache_dequeue_object(object
);
358 return transit_to(KILL_OBJECT
);
362 * initialise an object
363 * - check the specified object's parent to see if we can make use of it
364 * immediately to do a creation
365 * - we may need to start the process of creating a parent and we need to wait
366 * for the parent's lookup and creation to complete if it's not there yet
368 static const struct fscache_state
*fscache_initialise_object(struct fscache_object
*object
,
371 struct fscache_object
*parent
;
374 _enter("{OBJ%x},%d", object
->debug_id
, event
);
376 ASSERT(list_empty(&object
->dep_link
));
378 parent
= object
->parent
;
380 _leave(" [no parent]");
381 return transit_to(DROP_OBJECT
);
384 _debug("parent: %s of:%lx", parent
->state
->name
, parent
->flags
);
386 if (fscache_object_is_dying(parent
)) {
387 _leave(" [bad parent]");
388 return transit_to(DROP_OBJECT
);
391 if (fscache_object_is_available(parent
)) {
393 return transit_to(PARENT_READY
);
398 spin_lock(&parent
->lock
);
399 fscache_stat(&fscache_n_cop_grab_object
);
401 if (fscache_object_is_live(parent
) &&
402 object
->cache
->ops
->grab_object(object
, fscache_obj_get_add_to_deps
)) {
403 list_add(&object
->dep_link
, &parent
->dependents
);
406 fscache_stat_d(&fscache_n_cop_grab_object
);
407 spin_unlock(&parent
->lock
);
409 _leave(" [grab failed]");
410 return transit_to(DROP_OBJECT
);
413 /* fscache_acquire_non_index_cookie() uses this
414 * to wake the chain up */
415 fscache_raise_event(parent
, FSCACHE_OBJECT_EV_NEW_CHILD
);
417 return transit_to(WAIT_FOR_PARENT
);
421 * Once the parent object is ready, we should kick off our lookup op.
423 static const struct fscache_state
*fscache_parent_ready(struct fscache_object
*object
,
426 struct fscache_object
*parent
= object
->parent
;
428 _enter("{OBJ%x},%d", object
->debug_id
, event
);
430 ASSERT(parent
!= NULL
);
432 spin_lock(&parent
->lock
);
435 spin_unlock(&parent
->lock
);
438 return transit_to(LOOK_UP_OBJECT
);
442 * look an object up in the cache from which it was allocated
443 * - we hold an "access lock" on the parent object, so the parent object cannot
444 * be withdrawn by either party till we've finished
446 static const struct fscache_state
*fscache_look_up_object(struct fscache_object
*object
,
449 struct fscache_cookie
*cookie
= object
->cookie
;
450 struct fscache_object
*parent
= object
->parent
;
453 _enter("{OBJ%x},%d", object
->debug_id
, event
);
455 object
->oob_table
= fscache_osm_lookup_oob
;
457 ASSERT(parent
!= NULL
);
458 ASSERTCMP(parent
->n_ops
, >, 0);
459 ASSERTCMP(parent
->n_obj_ops
, >, 0);
461 /* make sure the parent is still available */
462 ASSERT(fscache_object_is_available(parent
));
464 if (fscache_object_is_dying(parent
) ||
465 test_bit(FSCACHE_IOERROR
, &object
->cache
->flags
) ||
466 !fscache_use_cookie(object
)) {
467 _leave(" [unavailable]");
468 return transit_to(LOOKUP_FAILURE
);
471 _debug("LOOKUP \"%s\" in \"%s\"",
472 cookie
->def
->name
, object
->cache
->tag
->name
);
474 fscache_stat(&fscache_n_object_lookups
);
475 fscache_stat(&fscache_n_cop_lookup_object
);
476 ret
= object
->cache
->ops
->lookup_object(object
);
477 fscache_stat_d(&fscache_n_cop_lookup_object
);
479 fscache_unuse_cookie(object
);
481 if (ret
== -ETIMEDOUT
) {
482 /* probably stuck behind another object, so move this one to
483 * the back of the queue */
484 fscache_stat(&fscache_n_object_lookups_timed_out
);
485 _leave(" [timeout]");
491 return transit_to(LOOKUP_FAILURE
);
495 return transit_to(OBJECT_AVAILABLE
);
499 * fscache_object_lookup_negative - Note negative cookie lookup
500 * @object: Object pointing to cookie to mark
502 * Note negative lookup, permitting those waiting to read data from an already
503 * existing backing object to continue as there's no data for them to read.
505 void fscache_object_lookup_negative(struct fscache_object
*object
)
507 struct fscache_cookie
*cookie
= object
->cookie
;
509 _enter("{OBJ%x,%s}", object
->debug_id
, object
->state
->name
);
511 if (!test_and_set_bit(FSCACHE_OBJECT_IS_LOOKED_UP
, &object
->flags
)) {
512 fscache_stat(&fscache_n_object_lookups_negative
);
514 /* Allow write requests to begin stacking up and read requests to begin
517 set_bit(FSCACHE_COOKIE_NO_DATA_YET
, &cookie
->flags
);
518 clear_bit(FSCACHE_COOKIE_UNAVAILABLE
, &cookie
->flags
);
520 clear_bit_unlock(FSCACHE_COOKIE_LOOKING_UP
, &cookie
->flags
);
521 wake_up_bit(&cookie
->flags
, FSCACHE_COOKIE_LOOKING_UP
);
525 EXPORT_SYMBOL(fscache_object_lookup_negative
);
528 * fscache_obtained_object - Note successful object lookup or creation
529 * @object: Object pointing to cookie to mark
531 * Note successful lookup and/or creation, permitting those waiting to write
532 * data to a backing object to continue.
534 * Note that after calling this, an object's cookie may be relinquished by the
535 * netfs, and so must be accessed with object lock held.
537 void fscache_obtained_object(struct fscache_object
*object
)
539 struct fscache_cookie
*cookie
= object
->cookie
;
541 _enter("{OBJ%x,%s}", object
->debug_id
, object
->state
->name
);
543 /* if we were still looking up, then we must have a positive lookup
544 * result, in which case there may be data available */
545 if (!test_and_set_bit(FSCACHE_OBJECT_IS_LOOKED_UP
, &object
->flags
)) {
546 fscache_stat(&fscache_n_object_lookups_positive
);
548 /* We do (presumably) have data */
549 clear_bit_unlock(FSCACHE_COOKIE_NO_DATA_YET
, &cookie
->flags
);
550 clear_bit(FSCACHE_COOKIE_UNAVAILABLE
, &cookie
->flags
);
552 /* Allow write requests to begin stacking up and read requests
553 * to begin shovelling data.
555 clear_bit_unlock(FSCACHE_COOKIE_LOOKING_UP
, &cookie
->flags
);
556 wake_up_bit(&cookie
->flags
, FSCACHE_COOKIE_LOOKING_UP
);
558 fscache_stat(&fscache_n_object_created
);
561 set_bit(FSCACHE_OBJECT_IS_AVAILABLE
, &object
->flags
);
564 EXPORT_SYMBOL(fscache_obtained_object
);
567 * handle an object that has just become available
569 static const struct fscache_state
*fscache_object_available(struct fscache_object
*object
,
572 _enter("{OBJ%x},%d", object
->debug_id
, event
);
574 object
->oob_table
= fscache_osm_run_oob
;
576 spin_lock(&object
->lock
);
578 fscache_done_parent_op(object
);
579 if (object
->n_in_progress
== 0) {
580 if (object
->n_ops
> 0) {
581 ASSERTCMP(object
->n_ops
, >=, object
->n_obj_ops
);
582 fscache_start_operations(object
);
584 ASSERT(list_empty(&object
->pending_ops
));
587 spin_unlock(&object
->lock
);
589 fscache_stat(&fscache_n_cop_lookup_complete
);
590 object
->cache
->ops
->lookup_complete(object
);
591 fscache_stat_d(&fscache_n_cop_lookup_complete
);
593 fscache_stat(&fscache_n_object_avail
);
596 return transit_to(JUMPSTART_DEPS
);
600 * Wake up this object's dependent objects now that we've become available.
602 static const struct fscache_state
*fscache_jumpstart_dependents(struct fscache_object
*object
,
605 _enter("{OBJ%x},%d", object
->debug_id
, event
);
607 if (!fscache_enqueue_dependents(object
, FSCACHE_OBJECT_EV_PARENT_READY
))
608 return NO_TRANSIT
; /* Not finished; requeue */
609 return transit_to(WAIT_FOR_CMD
);
613 * Handle lookup or creation failute.
615 static const struct fscache_state
*fscache_lookup_failure(struct fscache_object
*object
,
618 struct fscache_cookie
*cookie
;
620 _enter("{OBJ%x},%d", object
->debug_id
, event
);
622 object
->oob_event_mask
= 0;
624 fscache_stat(&fscache_n_cop_lookup_complete
);
625 object
->cache
->ops
->lookup_complete(object
);
626 fscache_stat_d(&fscache_n_cop_lookup_complete
);
628 set_bit(FSCACHE_OBJECT_KILLED_BY_CACHE
, &object
->flags
);
630 cookie
= object
->cookie
;
631 set_bit(FSCACHE_COOKIE_UNAVAILABLE
, &cookie
->flags
);
632 if (test_and_clear_bit(FSCACHE_COOKIE_LOOKING_UP
, &cookie
->flags
))
633 wake_up_bit(&cookie
->flags
, FSCACHE_COOKIE_LOOKING_UP
);
635 fscache_done_parent_op(object
);
636 return transit_to(KILL_OBJECT
);
640 * Wait for completion of all active operations on this object and the death of
641 * all child objects of this object.
643 static const struct fscache_state
*fscache_kill_object(struct fscache_object
*object
,
646 _enter("{OBJ%x,%d,%d},%d",
647 object
->debug_id
, object
->n_ops
, object
->n_children
, event
);
649 fscache_mark_object_dead(object
);
650 object
->oob_event_mask
= 0;
652 if (test_bit(FSCACHE_OBJECT_RETIRED
, &object
->flags
)) {
653 /* Reject any new read/write ops and abort any that are pending. */
654 clear_bit(FSCACHE_OBJECT_PENDING_WRITE
, &object
->flags
);
655 fscache_cancel_all_ops(object
);
658 if (list_empty(&object
->dependents
) &&
659 object
->n_ops
== 0 &&
660 object
->n_children
== 0)
661 return transit_to(DROP_OBJECT
);
663 if (object
->n_in_progress
== 0) {
664 spin_lock(&object
->lock
);
665 if (object
->n_ops
> 0 && object
->n_in_progress
== 0)
666 fscache_start_operations(object
);
667 spin_unlock(&object
->lock
);
670 if (!list_empty(&object
->dependents
))
671 return transit_to(KILL_DEPENDENTS
);
673 return transit_to(WAIT_FOR_CLEARANCE
);
677 * Kill dependent objects.
679 static const struct fscache_state
*fscache_kill_dependents(struct fscache_object
*object
,
682 _enter("{OBJ%x},%d", object
->debug_id
, event
);
684 if (!fscache_enqueue_dependents(object
, FSCACHE_OBJECT_EV_KILL
))
685 return NO_TRANSIT
; /* Not finished */
686 return transit_to(WAIT_FOR_CLEARANCE
);
690 * Drop an object's attachments
692 static const struct fscache_state
*fscache_drop_object(struct fscache_object
*object
,
695 struct fscache_object
*parent
= object
->parent
;
696 struct fscache_cookie
*cookie
= object
->cookie
;
697 struct fscache_cache
*cache
= object
->cache
;
700 _enter("{OBJ%x,%d},%d", object
->debug_id
, object
->n_children
, event
);
702 ASSERT(cookie
!= NULL
);
703 ASSERT(!hlist_unhashed(&object
->cookie_link
));
705 if (test_bit(FSCACHE_COOKIE_AUX_UPDATED
, &cookie
->flags
)) {
706 _debug("final update");
707 fscache_update_aux_data(object
);
710 /* Make sure the cookie no longer points here and that the netfs isn't
713 spin_lock(&cookie
->lock
);
714 hlist_del_init(&object
->cookie_link
);
715 if (hlist_empty(&cookie
->backing_objects
) &&
716 test_and_clear_bit(FSCACHE_COOKIE_INVALIDATING
, &cookie
->flags
))
718 spin_unlock(&cookie
->lock
);
721 wake_up_bit(&cookie
->flags
, FSCACHE_COOKIE_INVALIDATING
);
722 if (test_and_clear_bit(FSCACHE_COOKIE_LOOKING_UP
, &cookie
->flags
))
723 wake_up_bit(&cookie
->flags
, FSCACHE_COOKIE_LOOKING_UP
);
726 /* Prevent a race with our last child, which has to signal EV_CLEARED
727 * before dropping our spinlock.
729 spin_lock(&object
->lock
);
730 spin_unlock(&object
->lock
);
732 /* Discard from the cache's collection of objects */
733 spin_lock(&cache
->object_list_lock
);
734 list_del_init(&object
->cache_link
);
735 spin_unlock(&cache
->object_list_lock
);
737 fscache_stat(&fscache_n_cop_drop_object
);
738 cache
->ops
->drop_object(object
);
739 fscache_stat_d(&fscache_n_cop_drop_object
);
741 /* The parent object wants to know when all it dependents have gone */
743 _debug("release parent OBJ%x {%d}",
744 parent
->debug_id
, parent
->n_children
);
746 spin_lock(&parent
->lock
);
747 parent
->n_children
--;
748 if (parent
->n_children
== 0)
749 fscache_raise_event(parent
, FSCACHE_OBJECT_EV_CLEARED
);
750 spin_unlock(&parent
->lock
);
751 object
->parent
= NULL
;
754 /* this just shifts the object release to the work processor */
755 fscache_put_object(object
, fscache_obj_put_drop_obj
);
756 fscache_stat(&fscache_n_object_dead
);
759 return transit_to(OBJECT_DEAD
);
763 * get a ref on an object
765 static int fscache_get_object(struct fscache_object
*object
,
766 enum fscache_obj_ref_trace why
)
770 fscache_stat(&fscache_n_cop_grab_object
);
771 ret
= object
->cache
->ops
->grab_object(object
, why
) ? 0 : -EAGAIN
;
772 fscache_stat_d(&fscache_n_cop_grab_object
);
777 * Discard a ref on an object
779 static void fscache_put_object(struct fscache_object
*object
,
780 enum fscache_obj_ref_trace why
)
782 fscache_stat(&fscache_n_cop_put_object
);
783 object
->cache
->ops
->put_object(object
, why
);
784 fscache_stat_d(&fscache_n_cop_put_object
);
788 * fscache_object_destroy - Note that a cache object is about to be destroyed
789 * @object: The object to be destroyed
791 * Note the imminent destruction and deallocation of a cache object record.
793 void fscache_object_destroy(struct fscache_object
*object
)
795 /* We can get rid of the cookie now */
796 fscache_cookie_put(object
->cookie
, fscache_cookie_put_object
);
797 object
->cookie
= NULL
;
799 EXPORT_SYMBOL(fscache_object_destroy
);
802 * enqueue an object for metadata-type processing
804 void fscache_enqueue_object(struct fscache_object
*object
)
806 _enter("{OBJ%x}", object
->debug_id
);
808 if (fscache_get_object(object
, fscache_obj_get_queue
) >= 0) {
809 wait_queue_head_t
*cong_wq
=
810 &get_cpu_var(fscache_object_cong_wait
);
812 if (queue_work(fscache_object_wq
, &object
->work
)) {
813 if (fscache_object_congested())
816 fscache_put_object(object
, fscache_obj_put_queue
);
818 put_cpu_var(fscache_object_cong_wait
);
823 * fscache_object_sleep_till_congested - Sleep until object wq is congested
824 * @timeoutp: Scheduler sleep timeout
826 * Allow an object handler to sleep until the object workqueue is congested.
828 * The caller must set up a wake up event before calling this and must have set
829 * the appropriate sleep mode (such as TASK_UNINTERRUPTIBLE) and tested its own
830 * condition before calling this function as no test is made here.
832 * %true is returned if the object wq is congested, %false otherwise.
834 bool fscache_object_sleep_till_congested(signed long *timeoutp
)
836 wait_queue_head_t
*cong_wq
= this_cpu_ptr(&fscache_object_cong_wait
);
839 if (fscache_object_congested())
842 add_wait_queue_exclusive(cong_wq
, &wait
);
843 if (!fscache_object_congested())
844 *timeoutp
= schedule_timeout(*timeoutp
);
845 finish_wait(cong_wq
, &wait
);
847 return fscache_object_congested();
849 EXPORT_SYMBOL_GPL(fscache_object_sleep_till_congested
);
852 * Enqueue the dependents of an object for metadata-type processing.
854 * If we don't manage to finish the list before the scheduler wants to run
855 * again then return false immediately. We return true if the list was
858 static bool fscache_enqueue_dependents(struct fscache_object
*object
, int event
)
860 struct fscache_object
*dep
;
863 _enter("{OBJ%x}", object
->debug_id
);
865 if (list_empty(&object
->dependents
))
868 spin_lock(&object
->lock
);
870 while (!list_empty(&object
->dependents
)) {
871 dep
= list_entry(object
->dependents
.next
,
872 struct fscache_object
, dep_link
);
873 list_del_init(&dep
->dep_link
);
875 fscache_raise_event(dep
, event
);
876 fscache_put_object(dep
, fscache_obj_put_enq_dep
);
878 if (!list_empty(&object
->dependents
) && need_resched()) {
884 spin_unlock(&object
->lock
);
889 * remove an object from whatever queue it's waiting on
891 static void fscache_dequeue_object(struct fscache_object
*object
)
893 _enter("{OBJ%x}", object
->debug_id
);
895 if (!list_empty(&object
->dep_link
)) {
896 spin_lock(&object
->parent
->lock
);
897 list_del_init(&object
->dep_link
);
898 spin_unlock(&object
->parent
->lock
);
905 * fscache_check_aux - Ask the netfs whether an object on disk is still valid
906 * @object: The object to ask about
907 * @data: The auxiliary data for the object
908 * @datalen: The size of the auxiliary data
909 * @object_size: The size of the object according to the server.
911 * This function consults the netfs about the coherency state of an object.
912 * The caller must be holding a ref on cookie->n_active (held by
913 * fscache_look_up_object() on behalf of the cache backend during object lookup
916 enum fscache_checkaux
fscache_check_aux(struct fscache_object
*object
,
917 const void *data
, uint16_t datalen
,
920 enum fscache_checkaux result
;
922 if (!object
->cookie
->def
->check_aux
) {
923 fscache_stat(&fscache_n_checkaux_none
);
924 return FSCACHE_CHECKAUX_OKAY
;
927 result
= object
->cookie
->def
->check_aux(object
->cookie
->netfs_data
,
928 data
, datalen
, object_size
);
930 /* entry okay as is */
931 case FSCACHE_CHECKAUX_OKAY
:
932 fscache_stat(&fscache_n_checkaux_okay
);
935 /* entry requires update */
936 case FSCACHE_CHECKAUX_NEEDS_UPDATE
:
937 fscache_stat(&fscache_n_checkaux_update
);
940 /* entry requires deletion */
941 case FSCACHE_CHECKAUX_OBSOLETE
:
942 fscache_stat(&fscache_n_checkaux_obsolete
);
951 EXPORT_SYMBOL(fscache_check_aux
);
954 * Asynchronously invalidate an object.
956 static const struct fscache_state
*_fscache_invalidate_object(struct fscache_object
*object
,
959 struct fscache_operation
*op
;
960 struct fscache_cookie
*cookie
= object
->cookie
;
962 _enter("{OBJ%x},%d", object
->debug_id
, event
);
964 /* We're going to need the cookie. If the cookie is not available then
965 * retire the object instead.
967 if (!fscache_use_cookie(object
)) {
968 ASSERT(radix_tree_empty(&object
->cookie
->stores
));
969 set_bit(FSCACHE_OBJECT_RETIRED
, &object
->flags
);
970 _leave(" [no cookie]");
971 return transit_to(KILL_OBJECT
);
974 /* Reject any new read/write ops and abort any that are pending. */
975 fscache_invalidate_writes(cookie
);
976 clear_bit(FSCACHE_OBJECT_PENDING_WRITE
, &object
->flags
);
977 fscache_cancel_all_ops(object
);
979 /* Now we have to wait for in-progress reads and writes */
980 op
= kzalloc(sizeof(*op
), GFP_KERNEL
);
984 fscache_operation_init(cookie
, op
, object
->cache
->ops
->invalidate_object
,
986 op
->flags
= FSCACHE_OP_ASYNC
|
987 (1 << FSCACHE_OP_EXCLUSIVE
) |
988 (1 << FSCACHE_OP_UNUSE_COOKIE
);
989 trace_fscache_page_op(cookie
, NULL
, op
, fscache_page_op_invalidate
);
991 spin_lock(&cookie
->lock
);
992 if (fscache_submit_exclusive_op(object
, op
) < 0)
993 goto submit_op_failed
;
994 spin_unlock(&cookie
->lock
);
995 fscache_put_operation(op
);
997 /* Once we've completed the invalidation, we know there will be no data
998 * stored in the cache and thus we can reinstate the data-check-skip
1001 set_bit(FSCACHE_COOKIE_NO_DATA_YET
, &cookie
->flags
);
1003 /* We can allow read and write requests to come in once again. They'll
1004 * queue up behind our exclusive invalidation operation.
1006 if (test_and_clear_bit(FSCACHE_COOKIE_INVALIDATING
, &cookie
->flags
))
1007 wake_up_bit(&cookie
->flags
, FSCACHE_COOKIE_INVALIDATING
);
1009 return transit_to(UPDATE_OBJECT
);
1012 fscache_mark_object_dead(object
);
1013 fscache_unuse_cookie(object
);
1014 _leave(" [ENOMEM]");
1015 return transit_to(KILL_OBJECT
);
1018 fscache_mark_object_dead(object
);
1019 spin_unlock(&cookie
->lock
);
1020 fscache_unuse_cookie(object
);
1023 return transit_to(KILL_OBJECT
);
1026 static const struct fscache_state
*fscache_invalidate_object(struct fscache_object
*object
,
1029 const struct fscache_state
*s
;
1031 fscache_stat(&fscache_n_invalidates_run
);
1032 fscache_stat(&fscache_n_cop_invalidate_object
);
1033 s
= _fscache_invalidate_object(object
, event
);
1034 fscache_stat_d(&fscache_n_cop_invalidate_object
);
1039 * Update auxiliary data.
1041 static void fscache_update_aux_data(struct fscache_object
*object
)
1043 fscache_stat(&fscache_n_updates_run
);
1044 fscache_stat(&fscache_n_cop_update_object
);
1045 object
->cache
->ops
->update_object(object
);
1046 fscache_stat_d(&fscache_n_cop_update_object
);
1050 * Asynchronously update an object.
1052 static const struct fscache_state
*fscache_update_object(struct fscache_object
*object
,
1055 _enter("{OBJ%x},%d", object
->debug_id
, event
);
1057 fscache_update_aux_data(object
);
1060 return transit_to(WAIT_FOR_CMD
);
1064 * fscache_object_retrying_stale - Note retrying stale object
1065 * @object: The object that will be retried
1067 * Note that an object lookup found an on-disk object that was adjudged to be
1068 * stale and has been deleted. The lookup will be retried.
1070 void fscache_object_retrying_stale(struct fscache_object
*object
)
1072 fscache_stat(&fscache_n_cache_no_space_reject
);
1074 EXPORT_SYMBOL(fscache_object_retrying_stale
);
1077 * fscache_object_mark_killed - Note that an object was killed
1078 * @object: The object that was culled
1079 * @why: The reason the object was killed.
1081 * Note that an object was killed. Returns true if the object was
1082 * already marked killed, false if it wasn't.
1084 void fscache_object_mark_killed(struct fscache_object
*object
,
1085 enum fscache_why_object_killed why
)
1087 if (test_and_set_bit(FSCACHE_OBJECT_KILLED_BY_CACHE
, &object
->flags
)) {
1088 pr_err("Error: Object already killed by cache [%s]\n",
1089 object
->cache
->identifier
);
1094 case FSCACHE_OBJECT_NO_SPACE
:
1095 fscache_stat(&fscache_n_cache_no_space_reject
);
1097 case FSCACHE_OBJECT_IS_STALE
:
1098 fscache_stat(&fscache_n_cache_stale_objects
);
1100 case FSCACHE_OBJECT_WAS_RETIRED
:
1101 fscache_stat(&fscache_n_cache_retired_objects
);
1103 case FSCACHE_OBJECT_WAS_CULLED
:
1104 fscache_stat(&fscache_n_cache_culled_objects
);
1108 EXPORT_SYMBOL(fscache_object_mark_killed
);
1111 * The object is dead. We can get here if an object gets queued by an event
1112 * that would lead to its death (such as EV_KILL) when the dispatcher is
1113 * already running (and so can be requeued) but hasn't yet cleared the event
1116 static const struct fscache_state
*fscache_object_dead(struct fscache_object
*object
,
1119 if (!test_and_set_bit(FSCACHE_OBJECT_RUN_AFTER_DEAD
,
1123 WARN(true, "FS-Cache object redispatched after death");