| /* FS-Cache object state machine handler |
| * |
| * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved. |
| * Written by David Howells (dhowells@redhat.com) |
| * |
| * This program is free software; you can redistribute it and/or |
| * modify it under the terms of the GNU General Public License |
| * as published by the Free Software Foundation; either version |
| * 2 of the License, or (at your option) any later version. |
| * |
| * 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); |
| |
| #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", (void*)2UL); |
| |
| 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 *); |
| static void fscache_put_object(struct fscache_object *); |
| static bool fscache_enqueue_dependents(struct fscache_object *, int); |
| static void fscache_dequeue_object(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; |
| 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); |
| 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; |
| } |
| } |
| } |
| |
| /* 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; |
| 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); |
| |
| new_state = state->work(object, event); |
| event = -1; |
| if (new_state == NO_TRANSIT) { |
| _debug("{OBJ%x} %s notrans", object->debug_id, state->name); |
| 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->work == ((void *)2UL))) { |
| _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_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; |
| 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)) { |
| 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 (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)); |
| |
| /* 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); |
| |
| /* 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_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) |
| { |
| int ret; |
| |
| fscache_stat(&fscache_n_cop_grab_object); |
| ret = object->cache->ops->grab_object(object) ? 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) |
| { |
| fscache_stat(&fscache_n_cop_put_object); |
| object->cache->ops->put_object(object); |
| 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); |
| 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) >= 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); |
| |
| 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); |
| |
| 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) |
| { |
| 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); |
| 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(object->cookie->stores.rnode == NULL); |
| 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(op, object->cache->ops->invalidate_object, NULL); |
| op->flags = FSCACHE_OP_ASYNC | |
| (1 << FSCACHE_OP_EXCLUSIVE) | |
| (1 << FSCACHE_OP_UNUSE_COOKIE); |
| |
| 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; |
| } |
| |
| /* |
| * 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_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); |
| |
| _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); |