diff options
Diffstat (limited to 'fs/fscache/object.c')
| -rw-r--r-- | fs/fscache/object.c | 1133 |
1 files changed, 0 insertions, 1133 deletions
diff --git a/fs/fscache/object.c b/fs/fscache/object.c deleted file mode 100644 index cfeba839a0f2..000000000000 --- a/fs/fscache/object.c +++ /dev/null @@ -1,1133 +0,0 @@ -// SPDX-License-Identifier: GPL-2.0-or-later -/* FS-Cache object state machine handler - * - * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved. - * Written by David Howells (dhowells@redhat.com) - * - * See Documentation/filesystems/caching/object.txt for a description of the - * object state machine and the in-kernel representations. - */ - -#define FSCACHE_DEBUG_LEVEL COOKIE -#include <linux/module.h> -#include <linux/slab.h> -#include <linux/prefetch.h> -#include "internal.h" - -static const struct fscache_state *fscache_abort_initialisation(struct fscache_object *, int); -static const struct fscache_state *fscache_kill_dependents(struct fscache_object *, int); -static const struct fscache_state *fscache_drop_object(struct fscache_object *, int); -static const struct fscache_state *fscache_initialise_object(struct fscache_object *, int); -static const struct fscache_state *fscache_invalidate_object(struct fscache_object *, int); -static const struct fscache_state *fscache_jumpstart_dependents(struct fscache_object *, int); -static const struct fscache_state *fscache_kill_object(struct fscache_object *, int); -static const struct fscache_state *fscache_lookup_failure(struct fscache_object *, int); -static const struct fscache_state *fscache_look_up_object(struct fscache_object *, int); -static const struct fscache_state *fscache_object_available(struct fscache_object *, int); -static const struct fscache_state *fscache_parent_ready(struct fscache_object *, int); -static const struct fscache_state *fscache_update_object(struct fscache_object *, int); -static const struct fscache_state *fscache_object_dead(struct fscache_object *, int); - -#define __STATE_NAME(n) fscache_osm_##n -#define STATE(n) (&__STATE_NAME(n)) - -/* - * Define a work state. Work states are execution states. No event processing - * is performed by them. The function attached to a work state returns a - * pointer indicating the next state to which the state machine should - * transition. Returning NO_TRANSIT repeats the current state, but goes back - * to the scheduler first. - */ -#define WORK_STATE(n, sn, f) \ - const struct fscache_state __STATE_NAME(n) = { \ - .name = #n, \ - .short_name = sn, \ - .work = f \ - } - -/* - * Returns from work states. - */ -#define transit_to(state) ({ prefetch(&STATE(state)->work); STATE(state); }) - -#define NO_TRANSIT ((struct fscache_state *)NULL) - -/* - * Define a wait state. Wait states are event processing states. No execution - * is performed by them. Wait states are just tables of "if event X occurs, - * clear it and transition to state Y". The dispatcher returns to the - * scheduler if none of the events in which the wait state has an interest are - * currently pending. - */ -#define WAIT_STATE(n, sn, ...) \ - const struct fscache_state __STATE_NAME(n) = { \ - .name = #n, \ - .short_name = sn, \ - .work = NULL, \ - .transitions = { __VA_ARGS__, { 0, NULL } } \ - } - -#define TRANSIT_TO(state, emask) \ - { .events = (emask), .transit_to = STATE(state) } - -/* - * The object state machine. - */ -static WORK_STATE(INIT_OBJECT, "INIT", fscache_initialise_object); -static WORK_STATE(PARENT_READY, "PRDY", fscache_parent_ready); -static WORK_STATE(ABORT_INIT, "ABRT", fscache_abort_initialisation); -static WORK_STATE(LOOK_UP_OBJECT, "LOOK", fscache_look_up_object); -static WORK_STATE(CREATE_OBJECT, "CRTO", fscache_look_up_object); -static WORK_STATE(OBJECT_AVAILABLE, "AVBL", fscache_object_available); -static WORK_STATE(JUMPSTART_DEPS, "JUMP", fscache_jumpstart_dependents); - -static WORK_STATE(INVALIDATE_OBJECT, "INVL", fscache_invalidate_object); -static WORK_STATE(UPDATE_OBJECT, "UPDT", fscache_update_object); - -static WORK_STATE(LOOKUP_FAILURE, "LCFL", fscache_lookup_failure); -static WORK_STATE(KILL_OBJECT, "KILL", fscache_kill_object); -static WORK_STATE(KILL_DEPENDENTS, "KDEP", fscache_kill_dependents); -static WORK_STATE(DROP_OBJECT, "DROP", fscache_drop_object); -static WORK_STATE(OBJECT_DEAD, "DEAD", fscache_object_dead); - -static WAIT_STATE(WAIT_FOR_INIT, "?INI", - TRANSIT_TO(INIT_OBJECT, 1 << FSCACHE_OBJECT_EV_NEW_CHILD)); - -static WAIT_STATE(WAIT_FOR_PARENT, "?PRN", - TRANSIT_TO(PARENT_READY, 1 << FSCACHE_OBJECT_EV_PARENT_READY)); - -static WAIT_STATE(WAIT_FOR_CMD, "?CMD", - TRANSIT_TO(INVALIDATE_OBJECT, 1 << FSCACHE_OBJECT_EV_INVALIDATE), - TRANSIT_TO(UPDATE_OBJECT, 1 << FSCACHE_OBJECT_EV_UPDATE), - TRANSIT_TO(JUMPSTART_DEPS, 1 << FSCACHE_OBJECT_EV_NEW_CHILD)); - -static WAIT_STATE(WAIT_FOR_CLEARANCE, "?CLR", - TRANSIT_TO(KILL_OBJECT, 1 << FSCACHE_OBJECT_EV_CLEARED)); - -/* - * Out-of-band event transition tables. These are for handling unexpected - * events, such as an I/O error. If an OOB event occurs, the state machine - * clears and disables the event and forces a transition to the nominated work - * state (acurrently executing work states will complete first). - * - * In such a situation, object->state remembers the state the machine should - * have been in/gone to and returning NO_TRANSIT returns to that. - */ -static const struct fscache_transition fscache_osm_init_oob[] = { - TRANSIT_TO(ABORT_INIT, - (1 << FSCACHE_OBJECT_EV_ERROR) | - (1 << FSCACHE_OBJECT_EV_KILL)), - { 0, NULL } -}; - -static const struct fscache_transition fscache_osm_lookup_oob[] = { - TRANSIT_TO(LOOKUP_FAILURE, - (1 << FSCACHE_OBJECT_EV_ERROR) | - (1 << FSCACHE_OBJECT_EV_KILL)), - { 0, NULL } -}; - -static const struct fscache_transition fscache_osm_run_oob[] = { - TRANSIT_TO(KILL_OBJECT, - (1 << FSCACHE_OBJECT_EV_ERROR) | - (1 << FSCACHE_OBJECT_EV_KILL)), - { 0, NULL } -}; - -static int fscache_get_object(struct fscache_object *, - enum fscache_obj_ref_trace); -static void fscache_put_object(struct fscache_object *, - enum fscache_obj_ref_trace); -static bool fscache_enqueue_dependents(struct fscache_object *, int); -static void fscache_dequeue_object(struct fscache_object *); -static void fscache_update_aux_data(struct fscache_object *); - -/* - * we need to notify the parent when an op completes that we had outstanding - * upon it - */ -static inline void fscache_done_parent_op(struct fscache_object *object) -{ - struct fscache_object *parent = object->parent; - - _enter("OBJ%x {OBJ%x,%x}", - object->debug_id, parent->debug_id, parent->n_ops); - - spin_lock_nested(&parent->lock, 1); - parent->n_obj_ops--; - parent->n_ops--; - if (parent->n_ops == 0) - fscache_raise_event(parent, FSCACHE_OBJECT_EV_CLEARED); - spin_unlock(&parent->lock); -} - -/* - * Object state machine dispatcher. - */ -static void fscache_object_sm_dispatcher(struct fscache_object *object) -{ - const struct fscache_transition *t; - const struct fscache_state *state, *new_state; - unsigned long events, event_mask; - bool oob; - int event = -1; - - ASSERT(object != NULL); - - _enter("{OBJ%x,%s,%lx}", - object->debug_id, object->state->name, object->events); - - event_mask = object->event_mask; -restart: - object->event_mask = 0; /* Mask normal event handling */ - state = object->state; -restart_masked: - events = object->events; - - /* Handle any out-of-band events (typically an error) */ - if (events & object->oob_event_mask) { - _debug("{OBJ%x} oob %lx", - object->debug_id, events & object->oob_event_mask); - oob = true; - for (t = object->oob_table; t->events; t++) { - if (events & t->events) { - state = t->transit_to; - ASSERT(state->work != NULL); - event = fls(events & t->events) - 1; - __clear_bit(event, &object->oob_event_mask); - clear_bit(event, &object->events); - goto execute_work_state; - } - } - } - oob = false; - - /* Wait states are just transition tables */ - if (!state->work) { - if (events & event_mask) { - for (t = state->transitions; t->events; t++) { - if (events & t->events) { - new_state = t->transit_to; - event = fls(events & t->events) - 1; - trace_fscache_osm(object, state, - true, false, event); - clear_bit(event, &object->events); - _debug("{OBJ%x} ev %d: %s -> %s", - object->debug_id, event, - state->name, new_state->name); - object->state = state = new_state; - goto execute_work_state; - } - } - - /* The event mask didn't include all the tabled bits */ - BUG(); - } - /* Randomly woke up */ - goto unmask_events; - } - -execute_work_state: - _debug("{OBJ%x} exec %s", object->debug_id, state->name); - - trace_fscache_osm(object, state, false, oob, event); - new_state = state->work(object, event); - event = -1; - if (new_state == NO_TRANSIT) { - _debug("{OBJ%x} %s notrans", object->debug_id, state->name); - if (unlikely(state == STATE(OBJECT_DEAD))) { - _leave(" [dead]"); - return; - } - fscache_enqueue_object(object); - event_mask = object->oob_event_mask; - goto unmask_events; - } - - _debug("{OBJ%x} %s -> %s", - object->debug_id, state->name, new_state->name); - object->state = state = new_state; - - if (state->work) { - if (unlikely(state == STATE(OBJECT_DEAD))) { - _leave(" [dead]"); - return; - } - goto restart_masked; - } - - /* Transited to wait state */ - event_mask = object->oob_event_mask; - for (t = state->transitions; t->events; t++) - event_mask |= t->events; - -unmask_events: - object->event_mask = event_mask; - smp_mb(); - events = object->events; - if (events & event_mask) - goto restart; - _leave(" [msk %lx]", event_mask); -} - -/* - * execute an object - */ -static void fscache_object_work_func(struct work_struct *work) -{ - struct fscache_object *object = - container_of(work, struct fscache_object, work); - unsigned long start; - - _enter("{OBJ%x}", object->debug_id); - - start = jiffies; - fscache_object_sm_dispatcher(object); - fscache_hist(fscache_objs_histogram, start); - fscache_put_object(object, fscache_obj_put_work); -} - -/** - * fscache_object_init - Initialise a cache object description - * @object: Object description - * @cookie: Cookie object will be attached to - * @cache: Cache in which backing object will be found - * - * Initialise a cache object description to its basic values. - * - * See Documentation/filesystems/caching/backend-api.txt for a complete - * description. - */ -void fscache_object_init(struct fscache_object *object, - struct fscache_cookie *cookie, - struct fscache_cache *cache) -{ - const struct fscache_transition *t; - - atomic_inc(&cache->object_count); - - object->state = STATE(WAIT_FOR_INIT); - object->oob_table = fscache_osm_init_oob; - object->flags = 1 << FSCACHE_OBJECT_IS_LIVE; - spin_lock_init(&object->lock); - INIT_LIST_HEAD(&object->cache_link); - INIT_HLIST_NODE(&object->cookie_link); - INIT_WORK(&object->work, fscache_object_work_func); - INIT_LIST_HEAD(&object->dependents); - INIT_LIST_HEAD(&object->dep_link); - INIT_LIST_HEAD(&object->pending_ops); - object->n_children = 0; - object->n_ops = object->n_in_progress = object->n_exclusive = 0; - object->events = 0; - object->store_limit = 0; - object->store_limit_l = 0; - object->cache = cache; - object->cookie = cookie; - fscache_cookie_get(cookie, fscache_cookie_get_attach_object); - object->parent = NULL; -#ifdef CONFIG_FSCACHE_OBJECT_LIST - RB_CLEAR_NODE(&object->objlist_link); -#endif - - object->oob_event_mask = 0; - for (t = object->oob_table; t->events; t++) - object->oob_event_mask |= t->events; - object->event_mask = object->oob_event_mask; - for (t = object->state->transitions; t->events; t++) - object->event_mask |= t->events; -} -EXPORT_SYMBOL(fscache_object_init); - -/* - * Mark the object as no longer being live, making sure that we synchronise - * against op submission. - */ -static inline void fscache_mark_object_dead(struct fscache_object *object) -{ - spin_lock(&object->lock); - clear_bit(FSCACHE_OBJECT_IS_LIVE, &object->flags); - spin_unlock(&object->lock); -} - -/* - * Abort object initialisation before we start it. - */ -static const struct fscache_state *fscache_abort_initialisation(struct fscache_object *object, - int event) -{ - _enter("{OBJ%x},%d", object->debug_id, event); - - object->oob_event_mask = 0; - fscache_dequeue_object(object); - return transit_to(KILL_OBJECT); -} - -/* - * initialise an object - * - check the specified object's parent to see if we can make use of it - * immediately to do a creation - * - we may need to start the process of creating a parent and we need to wait - * for the parent's lookup and creation to complete if it's not there yet - */ -static const struct fscache_state *fscache_initialise_object(struct fscache_object *object, - int event) -{ - struct fscache_object *parent; - bool success; - - _enter("{OBJ%x},%d", object->debug_id, event); - - ASSERT(list_empty(&object->dep_link)); - - parent = object->parent; - if (!parent) { - _leave(" [no parent]"); - return transit_to(DROP_OBJECT); - } - - _debug("parent: %s of:%lx", parent->state->name, parent->flags); - - if (fscache_object_is_dying(parent)) { - _leave(" [bad parent]"); - return transit_to(DROP_OBJECT); - } - - if (fscache_object_is_available(parent)) { - _leave(" [ready]"); - return transit_to(PARENT_READY); - } - - _debug("wait"); - - spin_lock(&parent->lock); - fscache_stat(&fscache_n_cop_grab_object); - success = false; - if (fscache_object_is_live(parent) && - object->cache->ops->grab_object(object, fscache_obj_get_add_to_deps)) { - list_add(&object->dep_link, &parent->dependents); - success = true; - } - fscache_stat_d(&fscache_n_cop_grab_object); - spin_unlock(&parent->lock); - if (!success) { - _leave(" [grab failed]"); - return transit_to(DROP_OBJECT); - } - - /* fscache_acquire_non_index_cookie() uses this - * to wake the chain up */ - fscache_raise_event(parent, FSCACHE_OBJECT_EV_NEW_CHILD); - _leave(" [wait]"); - return transit_to(WAIT_FOR_PARENT); -} - -/* - * Once the parent object is ready, we should kick off our lookup op. - */ -static const struct fscache_state *fscache_parent_ready(struct fscache_object *object, - int event) -{ - struct fscache_object *parent = object->parent; - - _enter("{OBJ%x},%d", object->debug_id, event); - - ASSERT(parent != NULL); - - spin_lock(&parent->lock); - parent->n_ops++; - parent->n_obj_ops++; - object->lookup_jif = jiffies; - spin_unlock(&parent->lock); - - _leave(""); - return transit_to(LOOK_UP_OBJECT); -} - -/* - * look an object up in the cache from which it was allocated - * - we hold an "access lock" on the parent object, so the parent object cannot - * be withdrawn by either party till we've finished - */ -static const struct fscache_state *fscache_look_up_object(struct fscache_object *object, - int event) -{ - struct fscache_cookie *cookie = object->cookie; - struct fscache_object *parent = object->parent; - int ret; - - _enter("{OBJ%x},%d", object->debug_id, event); - - object->oob_table = fscache_osm_lookup_oob; - - ASSERT(parent != NULL); - ASSERTCMP(parent->n_ops, >, 0); - ASSERTCMP(parent->n_obj_ops, >, 0); - - /* make sure the parent is still available */ - ASSERT(fscache_object_is_available(parent)); - - if (fscache_object_is_dying(parent) || - test_bit(FSCACHE_IOERROR, &object->cache->flags) || - !fscache_use_cookie(object)) { - _leave(" [unavailable]"); - return transit_to(LOOKUP_FAILURE); - } - - _debug("LOOKUP \"%s\" in \"%s\"", - cookie->def->name, object->cache->tag->name); - - fscache_stat(&fscache_n_object_lookups); - fscache_stat(&fscache_n_cop_lookup_object); - ret = object->cache->ops->lookup_object(object); - fscache_stat_d(&fscache_n_cop_lookup_object); - - fscache_unuse_cookie(object); - - if (ret == -ETIMEDOUT) { - /* probably stuck behind another object, so move this one to - * the back of the queue */ - fscache_stat(&fscache_n_object_lookups_timed_out); - _leave(" [timeout]"); - return NO_TRANSIT; - } - - if (ret < 0) { - _leave(" [error]"); - return transit_to(LOOKUP_FAILURE); - } - - _leave(" [ok]"); - return transit_to(OBJECT_AVAILABLE); -} - -/** - * fscache_object_lookup_negative - Note negative cookie lookup - * @object: Object pointing to cookie to mark - * - * Note negative lookup, permitting those waiting to read data from an already - * existing backing object to continue as there's no data for them to read. - */ -void fscache_object_lookup_negative(struct fscache_object *object) -{ - struct fscache_cookie *cookie = object->cookie; - - _enter("{OBJ%x,%s}", object->debug_id, object->state->name); - - if (!test_and_set_bit(FSCACHE_OBJECT_IS_LOOKED_UP, &object->flags)) { - fscache_stat(&fscache_n_object_lookups_negative); - - /* Allow write requests to begin stacking up and read requests to begin - * returning ENODATA. - */ - set_bit(FSCACHE_COOKIE_NO_DATA_YET, &cookie->flags); - clear_bit(FSCACHE_COOKIE_UNAVAILABLE, &cookie->flags); - - _debug("wake up lookup %p", &cookie->flags); - clear_bit_unlock(FSCACHE_COOKIE_LOOKING_UP, &cookie->flags); - wake_up_bit(&cookie->flags, FSCACHE_COOKIE_LOOKING_UP); - } - _leave(""); -} -EXPORT_SYMBOL(fscache_object_lookup_negative); - -/** - * fscache_obtained_object - Note successful object lookup or creation - * @object: Object pointing to cookie to mark - * - * Note successful lookup and/or creation, permitting those waiting to write - * data to a backing object to continue. - * - * Note that after calling this, an object's cookie may be relinquished by the - * netfs, and so must be accessed with object lock held. - */ -void fscache_obtained_object(struct fscache_object *object) -{ - struct fscache_cookie *cookie = object->cookie; - - _enter("{OBJ%x,%s}", object->debug_id, object->state->name); - - /* if we were still looking up, then we must have a positive lookup - * result, in which case there may be data available */ - if (!test_and_set_bit(FSCACHE_OBJECT_IS_LOOKED_UP, &object->flags)) { - fscache_stat(&fscache_n_object_lookups_positive); - - /* We do (presumably) have data */ - clear_bit_unlock(FSCACHE_COOKIE_NO_DATA_YET, &cookie->flags); - clear_bit(FSCACHE_COOKIE_UNAVAILABLE, &cookie->flags); - - /* Allow write requests to begin stacking up and read requests - * to begin shovelling data. - */ - clear_bit_unlock(FSCACHE_COOKIE_LOOKING_UP, &cookie->flags); - wake_up_bit(&cookie->flags, FSCACHE_COOKIE_LOOKING_UP); - } else { - fscache_stat(&fscache_n_object_created); - } - - set_bit(FSCACHE_OBJECT_IS_AVAILABLE, &object->flags); - _leave(""); -} -EXPORT_SYMBOL(fscache_obtained_object); - -/* - * handle an object that has just become available - */ -static const struct fscache_state *fscache_object_available(struct fscache_object *object, - int event) -{ - _enter("{OBJ%x},%d", object->debug_id, event); - - object->oob_table = fscache_osm_run_oob; - - spin_lock(&object->lock); - - fscache_done_parent_op(object); - if (object->n_in_progress == 0) { - if (object->n_ops > 0) { - ASSERTCMP(object->n_ops, >=, object->n_obj_ops); - fscache_start_operations(object); - } else { - ASSERT(list_empty(&object->pending_ops)); - } - } - spin_unlock(&object->lock); - - fscache_stat(&fscache_n_cop_lookup_complete); - object->cache->ops->lookup_complete(object); - fscache_stat_d(&fscache_n_cop_lookup_complete); - - fscache_hist(fscache_obj_instantiate_histogram, object->lookup_jif); - fscache_stat(&fscache_n_object_avail); - - _leave(""); - return transit_to(JUMPSTART_DEPS); -} - -/* - * Wake up this object's dependent objects now that we've become available. - */ -static const struct fscache_state *fscache_jumpstart_dependents(struct fscache_object *object, - int event) -{ - _enter("{OBJ%x},%d", object->debug_id, event); - - if (!fscache_enqueue_dependents(object, FSCACHE_OBJECT_EV_PARENT_READY)) - return NO_TRANSIT; /* Not finished; requeue */ - return transit_to(WAIT_FOR_CMD); -} - -/* - * Handle lookup or creation failute. - */ -static const struct fscache_state *fscache_lookup_failure(struct fscache_object *object, - int event) -{ - struct fscache_cookie *cookie; - - _enter("{OBJ%x},%d", object->debug_id, event); - - object->oob_event_mask = 0; - - fscache_stat(&fscache_n_cop_lookup_complete); - object->cache->ops->lookup_complete(object); - fscache_stat_d(&fscache_n_cop_lookup_complete); - - set_bit(FSCACHE_OBJECT_KILLED_BY_CACHE, &object->flags); - - cookie = object->cookie; - set_bit(FSCACHE_COOKIE_UNAVAILABLE, &cookie->flags); - if (test_and_clear_bit(FSCACHE_COOKIE_LOOKING_UP, &cookie->flags)) - wake_up_bit(&cookie->flags, FSCACHE_COOKIE_LOOKING_UP); - - fscache_done_parent_op(object); - return transit_to(KILL_OBJECT); -} - -/* - * Wait for completion of all active operations on this object and the death of - * all child objects of this object. - */ -static const struct fscache_state *fscache_kill_object(struct fscache_object *object, - int event) -{ - _enter("{OBJ%x,%d,%d},%d", - object->debug_id, object->n_ops, object->n_children, event); - - fscache_mark_object_dead(object); - object->oob_event_mask = 0; - - if (test_bit(FSCACHE_OBJECT_RETIRED, &object->flags)) { - /* Reject any new read/write ops and abort any that are pending. */ - clear_bit(FSCACHE_OBJECT_PENDING_WRITE, &object->flags); - fscache_cancel_all_ops(object); - } - - if (list_empty(&object->dependents) && - object->n_ops == 0 && - object->n_children == 0) - return transit_to(DROP_OBJECT); - - if (object->n_in_progress == 0) { - spin_lock(&object->lock); - if (object->n_ops > 0 && object->n_in_progress == 0) - fscache_start_operations(object); - spin_unlock(&object->lock); - } - - if (!list_empty(&object->dependents)) - return transit_to(KILL_DEPENDENTS); - - return transit_to(WAIT_FOR_CLEARANCE); -} - -/* - * Kill dependent objects. - */ -static const struct fscache_state *fscache_kill_dependents(struct fscache_object *object, - int event) -{ - _enter("{OBJ%x},%d", object->debug_id, event); - - if (!fscache_enqueue_dependents(object, FSCACHE_OBJECT_EV_KILL)) - return NO_TRANSIT; /* Not finished */ - return transit_to(WAIT_FOR_CLEARANCE); -} - -/* - * Drop an object's attachments - */ -static const struct fscache_state *fscache_drop_object(struct fscache_object *object, - int event) -{ - struct fscache_object *parent = object->parent; - struct fscache_cookie *cookie = object->cookie; - struct fscache_cache *cache = object->cache; - bool awaken = false; - - _enter("{OBJ%x,%d},%d", object->debug_id, object->n_children, event); - - ASSERT(cookie != NULL); - ASSERT(!hlist_unhashed(&object->cookie_link)); - - if (test_bit(FSCACHE_COOKIE_AUX_UPDATED, &cookie->flags)) { - _debug("final update"); - fscache_update_aux_data(object); - } - - /* Make sure the cookie no longer points here and that the netfs isn't - * waiting for us. - */ - spin_lock(&cookie->lock); - hlist_del_init(&object->cookie_link); - if (hlist_empty(&cookie->backing_objects) && - test_and_clear_bit(FSCACHE_COOKIE_INVALIDATING, &cookie->flags)) - awaken = true; - spin_unlock(&cookie->lock); - - if (awaken) - wake_up_bit(&cookie->flags, FSCACHE_COOKIE_INVALIDATING); - if (test_and_clear_bit(FSCACHE_COOKIE_LOOKING_UP, &cookie->flags)) - wake_up_bit(&cookie->flags, FSCACHE_COOKIE_LOOKING_UP); - - - /* Prevent a race with our last child, which has to signal EV_CLEARED - * before dropping our spinlock. - */ - spin_lock(&object->lock); - spin_unlock(&object->lock); - - /* Discard from the cache's collection of objects */ - spin_lock(&cache->object_list_lock); - list_del_init(&object->cache_link); - spin_unlock(&cache->object_list_lock); - - fscache_stat(&fscache_n_cop_drop_object); - cache->ops->drop_object(object); - fscache_stat_d(&fscache_n_cop_drop_object); - - /* The parent object wants to know when all it dependents have gone */ - if (parent) { - _debug("release parent OBJ%x {%d}", - parent->debug_id, parent->n_children); - - spin_lock(&parent->lock); - parent->n_children--; - if (parent->n_children == 0) - fscache_raise_event(parent, FSCACHE_OBJECT_EV_CLEARED); - spin_unlock(&parent->lock); - object->parent = NULL; - } - - /* this just shifts the object release to the work processor */ - fscache_put_object(object, fscache_obj_put_drop_obj); - fscache_stat(&fscache_n_object_dead); - - _leave(""); - return transit_to(OBJECT_DEAD); -} - -/* - * get a ref on an object - */ -static int fscache_get_object(struct fscache_object *object, - enum fscache_obj_ref_trace why) -{ - int ret; - - fscache_stat(&fscache_n_cop_grab_object); - ret = object->cache->ops->grab_object(object, why) ? 0 : -EAGAIN; - fscache_stat_d(&fscache_n_cop_grab_object); - return ret; -} - -/* - * Discard a ref on an object - */ -static void fscache_put_object(struct fscache_object *object, - enum fscache_obj_ref_trace why) -{ - fscache_stat(&fscache_n_cop_put_object); - object->cache->ops->put_object(object, why); - fscache_stat_d(&fscache_n_cop_put_object); -} - -/** - * fscache_object_destroy - Note that a cache object is about to be destroyed - * @object: The object to be destroyed - * - * Note the imminent destruction and deallocation of a cache object record. - */ -void fscache_object_destroy(struct fscache_object *object) -{ - fscache_objlist_remove(object); - - /* We can get rid of the cookie now */ - fscache_cookie_put(object->cookie, fscache_cookie_put_object); - object->cookie = NULL; -} -EXPORT_SYMBOL(fscache_object_destroy); - -/* - * enqueue an object for metadata-type processing - */ -void fscache_enqueue_object(struct fscache_object *object) -{ - _enter("{OBJ%x}", object->debug_id); - - if (fscache_get_object(object, fscache_obj_get_queue) >= 0) { - wait_queue_head_t *cong_wq = - &get_cpu_var(fscache_object_cong_wait); - - if (queue_work(fscache_object_wq, &object->work)) { - if (fscache_object_congested()) - wake_up(cong_wq); - } else - fscache_put_object(object, fscache_obj_put_queue); - - put_cpu_var(fscache_object_cong_wait); - } -} - -/** - * fscache_object_sleep_till_congested - Sleep until object wq is congested - * @timeoutp: Scheduler sleep timeout - * - * Allow an object handler to sleep until the object workqueue is congested. - * - * The caller must set up a wake up event before calling this and must have set - * the appropriate sleep mode (such as TASK_UNINTERRUPTIBLE) and tested its own - * condition before calling this function as no test is made here. - * - * %true is returned if the object wq is congested, %false otherwise. - */ -bool fscache_object_sleep_till_congested(signed long *timeoutp) -{ - wait_queue_head_t *cong_wq = this_cpu_ptr(&fscache_object_cong_wait); - DEFINE_WAIT(wait); - - if (fscache_object_congested()) - return true; - - add_wait_queue_exclusive(cong_wq, &wait); - if (!fscache_object_congested()) - *timeoutp = schedule_timeout(*timeoutp); - finish_wait(cong_wq, &wait); - - return fscache_object_congested(); -} -EXPORT_SYMBOL_GPL(fscache_object_sleep_till_congested); - -/* - * Enqueue the dependents of an object for metadata-type processing. - * - * If we don't manage to finish the list before the scheduler wants to run - * again then return false immediately. We return true if the list was - * cleared. - */ -static bool fscache_enqueue_dependents(struct fscache_object *object, int event) -{ - struct fscache_object *dep; - bool ret = true; - - _enter("{OBJ%x}", object->debug_id); - - if (list_empty(&object->dependents)) - return true; - - spin_lock(&object->lock); - - while (!list_empty(&object->dependents)) { - dep = list_entry(object->dependents.next, - struct fscache_object, dep_link); - list_del_init(&dep->dep_link); - - fscache_raise_event(dep, event); - fscache_put_object(dep, fscache_obj_put_enq_dep); - - if (!list_empty(&object->dependents) && need_resched()) { - ret = false; - break; - } - } - - spin_unlock(&object->lock); - return ret; -} - -/* - * remove an object from whatever queue it's waiting on - */ -static void fscache_dequeue_object(struct fscache_object *object) -{ - _enter("{OBJ%x}", object->debug_id); - - if (!list_empty(&object->dep_link)) { - spin_lock(&object->parent->lock); - list_del_init(&object->dep_link); - spin_unlock(&object->parent->lock); - } - - _leave(""); -} - -/** - * fscache_check_aux - Ask the netfs whether an object on disk is still valid - * @object: The object to ask about - * @data: The auxiliary data for the object - * @datalen: The size of the auxiliary data - * - * This function consults the netfs about the coherency state of an object. - * The caller must be holding a ref on cookie->n_active (held by - * fscache_look_up_object() on behalf of the cache backend during object lookup - * and creation). - */ -enum fscache_checkaux fscache_check_aux(struct fscache_object *object, - const void *data, uint16_t datalen, - loff_t object_size) -{ - enum fscache_checkaux result; - - if (!object->cookie->def->check_aux) { - fscache_stat(&fscache_n_checkaux_none); - return FSCACHE_CHECKAUX_OKAY; - } - - result = object->cookie->def->check_aux(object->cookie->netfs_data, - data, datalen, object_size); - switch (result) { - /* entry okay as is */ - case FSCACHE_CHECKAUX_OKAY: - fscache_stat(&fscache_n_checkaux_okay); - break; - - /* entry requires update */ - case FSCACHE_CHECKAUX_NEEDS_UPDATE: - fscache_stat(&fscache_n_checkaux_update); - break; - - /* entry requires deletion */ - case FSCACHE_CHECKAUX_OBSOLETE: - fscache_stat(&fscache_n_checkaux_obsolete); - break; - - default: - BUG(); - } - - return result; -} -EXPORT_SYMBOL(fscache_check_aux); - -/* - * Asynchronously invalidate an object. - */ -static const struct fscache_state *_fscache_invalidate_object(struct fscache_object *object, - int event) -{ - struct fscache_operation *op; - struct fscache_cookie *cookie = object->cookie; - - _enter("{OBJ%x},%d", object->debug_id, event); - - /* We're going to need the cookie. If the cookie is not available then - * retire the object instead. - */ - if (!fscache_use_cookie(object)) { - ASSERT(radix_tree_empty(&object->cookie->stores)); - set_bit(FSCACHE_OBJECT_RETIRED, &object->flags); - _leave(" [no cookie]"); - return transit_to(KILL_OBJECT); - } - - /* Reject any new read/write ops and abort any that are pending. */ - fscache_invalidate_writes(cookie); - clear_bit(FSCACHE_OBJECT_PENDING_WRITE, &object->flags); - fscache_cancel_all_ops(object); - - /* Now we have to wait for in-progress reads and writes */ - op = kzalloc(sizeof(*op), GFP_KERNEL); - if (!op) - goto nomem; - - fscache_operation_init(cookie, op, object->cache->ops->invalidate_object, - NULL, NULL); - op->flags = FSCACHE_OP_ASYNC | - (1 << FSCACHE_OP_EXCLUSIVE) | - (1 << FSCACHE_OP_UNUSE_COOKIE); - trace_fscache_page_op(cookie, NULL, op, fscache_page_op_invalidate); - - spin_lock(&cookie->lock); - if (fscache_submit_exclusive_op(object, op) < 0) - goto submit_op_failed; - spin_unlock(&cookie->lock); - fscache_put_operation(op); - - /* Once we've completed the invalidation, we know there will be no data - * stored in the cache and thus we can reinstate the data-check-skip - * optimisation. - */ - set_bit(FSCACHE_COOKIE_NO_DATA_YET, &cookie->flags); - - /* We can allow read and write requests to come in once again. They'll - * queue up behind our exclusive invalidation operation. - */ - if (test_and_clear_bit(FSCACHE_COOKIE_INVALIDATING, &cookie->flags)) - wake_up_bit(&cookie->flags, FSCACHE_COOKIE_INVALIDATING); - _leave(" [ok]"); - return transit_to(UPDATE_OBJECT); - -nomem: - fscache_mark_object_dead(object); - fscache_unuse_cookie(object); - _leave(" [ENOMEM]"); - return transit_to(KILL_OBJECT); - -submit_op_failed: - fscache_mark_object_dead(object); - spin_unlock(&cookie->lock); - fscache_unuse_cookie(object); - kfree(op); - _leave(" [EIO]"); - return transit_to(KILL_OBJECT); -} - -static const struct fscache_state *fscache_invalidate_object(struct fscache_object *object, - int event) -{ - const struct fscache_state *s; - - fscache_stat(&fscache_n_invalidates_run); - fscache_stat(&fscache_n_cop_invalidate_object); - s = _fscache_invalidate_object(object, event); - fscache_stat_d(&fscache_n_cop_invalidate_object); - return s; -} - -/* - * Update auxiliary data. - */ -static void fscache_update_aux_data(struct fscache_object *object) -{ - 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); -} - -/* - * Asynchronously update an object. - */ -static const struct fscache_state *fscache_update_object(struct fscache_object *object, - int event) -{ - _enter("{OBJ%x},%d", object->debug_id, event); - - fscache_update_aux_data(object); - - _leave(""); - return transit_to(WAIT_FOR_CMD); -} - -/** - * fscache_object_retrying_stale - Note retrying stale object - * @object: The object that will be retried - * - * Note that an object lookup found an on-disk object that was adjudged to be - * stale and has been deleted. The lookup will be retried. - */ -void fscache_object_retrying_stale(struct fscache_object *object) -{ - fscache_stat(&fscache_n_cache_no_space_reject); -} -EXPORT_SYMBOL(fscache_object_retrying_stale); - -/** - * fscache_object_mark_killed - Note that an object was killed - * @object: The object that was culled - * @why: The reason the object was killed. - * - * Note that an object was killed. Returns true if the object was - * already marked killed, false if it wasn't. - */ -void fscache_object_mark_killed(struct fscache_object *object, - enum fscache_why_object_killed why) -{ - if (test_and_set_bit(FSCACHE_OBJECT_KILLED_BY_CACHE, &object->flags)) { - pr_err("Error: Object already killed by cache [%s]\n", - object->cache->identifier); - return; - } - - switch (why) { - case FSCACHE_OBJECT_NO_SPACE: - fscache_stat(&fscache_n_cache_no_space_reject); - break; - case FSCACHE_OBJECT_IS_STALE: - fscache_stat(&fscache_n_cache_stale_objects); - break; - case FSCACHE_OBJECT_WAS_RETIRED: - fscache_stat(&fscache_n_cache_retired_objects); - break; - case FSCACHE_OBJECT_WAS_CULLED: - fscache_stat(&fscache_n_cache_culled_objects); - break; - } -} -EXPORT_SYMBOL(fscache_object_mark_killed); - -/* - * The object is dead. We can get here if an object gets queued by an event - * that would lead to its death (such as EV_KILL) when the dispatcher is - * already running (and so can be requeued) but hasn't yet cleared the event - * mask. - */ -static const struct fscache_state *fscache_object_dead(struct fscache_object *object, - int event) -{ - if (!test_and_set_bit(FSCACHE_OBJECT_RUN_AFTER_DEAD, - &object->flags)) - return NO_TRANSIT; - - WARN(true, "FS-Cache object redispatched after death"); - return NO_TRANSIT; -} |