// 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.rst 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;
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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:
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_debug("{OBJ%x} exec %s", object->debug_id, state->name);
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trace_fscache_osm(object, state, false, oob, event);
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new_state = state->work(object, event);
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event = -1;
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if (new_state == NO_TRANSIT) {
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_debug("{OBJ%x} %s notrans", object->debug_id, state->name);
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if (unlikely(state == STATE(OBJECT_DEAD))) {
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_leave(" [dead]");
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return;
|
}
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fscache_enqueue_object(object);
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event_mask = object->oob_event_mask;
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goto unmask_events;
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}
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|
_debug("{OBJ%x} %s -> %s",
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object->debug_id, state->name, new_state->name);
|
object->state = state = new_state;
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if (state->work) {
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if (unlikely(state == STATE(OBJECT_DEAD))) {
|
_leave(" [dead]");
|
return;
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}
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goto restart_masked;
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}
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/* Transited to wait state */
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event_mask = object->oob_event_mask;
|
for (t = state->transitions; t->events; t++)
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event_mask |= t->events;
|
|
unmask_events:
|
object->event_mask = event_mask;
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smp_mb();
|
events = object->events;
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if (events & event_mask)
|
goto restart;
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_leave(" [msk %lx]", event_mask);
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}
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|
/*
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* execute an object
|
*/
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static void fscache_object_work_func(struct work_struct *work)
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{
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struct fscache_object *object =
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container_of(work, struct fscache_object, work);
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unsigned long start;
|
|
_enter("{OBJ%x}", object->debug_id);
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|
start = jiffies;
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fscache_object_sm_dispatcher(object);
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fscache_hist(fscache_objs_histogram, start);
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fscache_put_object(object, fscache_obj_put_work);
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}
|
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/**
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* 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.rst for a complete
|
* description.
|
*/
|
void fscache_object_init(struct fscache_object *object,
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struct fscache_cookie *cookie,
|
struct fscache_cache *cache)
|
{
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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);
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INIT_HLIST_NODE(&object->cookie_link);
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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;
|
}
|
