/*
* execute an object
*/
static void fscache_object_slow_work_execute(struct slow_work *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_state_machine(object);
fscache_hist(fscache_objs_histogram, start);
if (object->events & object->event_mask)
fscache_enqueue_object(object);
clear_bit(FSCACHE_OBJECT_EV_REQUEUE, &object->events);
}
/*
* 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
* - an object's cookie is pinned until we clear FSCACHE_COOKIE_CREATING on the
* leaf-most cookies of the object and all its children
*/
static void fscache_initialise_object(struct fscache_object *object)
{
struct fscache_object *parent;
_enter("");
ASSERT(object->cookie != NULL);
ASSERT(object->cookie->parent != NULL);
ASSERT(list_empty(&object->work.link));
if (object->events & ((1 << FSCACHE_OBJECT_EV_ERROR) |
(1 << FSCACHE_OBJECT_EV_RELEASE) |
(1 << FSCACHE_OBJECT_EV_RETIRE) |
(1 << FSCACHE_OBJECT_EV_WITHDRAW))) {
_debug("abort init %lx", object->events);
spin_lock(&object->lock);
object->state = FSCACHE_OBJECT_ABORT_INIT;
spin_unlock(&object->lock);
return;
}
spin_lock(&object->cookie->lock);
spin_lock_nested(&object->cookie->parent->lock, 1);
parent = object->parent;
if (!parent) {
_debug("no parent");
set_bit(FSCACHE_OBJECT_EV_WITHDRAW, &object->events);
} else {
spin_lock(&object->lock);
spin_lock_nested(&parent->lock, 1);
_debug("parent %s", fscache_object_states[parent->state]);
if (parent->state >= FSCACHE_OBJECT_DYING) {
_debug("bad parent");
set_bit(FSCACHE_OBJECT_EV_WITHDRAW, &object->events);
} else if (parent->state < FSCACHE_OBJECT_AVAILABLE) {
_debug("wait");
/* we may get woken up in this state by child objects
* binding on to us, so we need to make sure we don't
* add ourself to the list multiple times */
if (list_empty(&object->dep_link)) {
fscache_stat(&fscache_n_cop_grab_object);
object->cache->ops->grab_object(object);
fscache_stat_d(&fscache_n_cop_grab_object);
list_add(&object->dep_link,
&parent->dependents);
/* fscache_acquire_non_index_cookie() uses this
* to wake the chain up */
if (parent->state == FSCACHE_OBJECT_INIT)
fscache_enqueue_object(parent);
}
} else {
_debug("go");
parent->n_ops++;
parent->n_obj_ops++;
object->lookup_jif = jiffies;
object->state = FSCACHE_OBJECT_LOOKING_UP;
set_bit(FSCACHE_OBJECT_EV_REQUEUE, &object->events);
}
spin_unlock(&parent->lock);
spin_unlock(&object->lock);
}
spin_unlock(&object->cookie->parent->lock);
spin_unlock(&object->cookie->lock);
_leave("");
}
static void fscache_initialise_object(struct fscache_object *object)
{
struct fscache_object *parent;
_enter("");
ASSERT(object->cookie != NULL);
ASSERT(object->cookie->parent != NULL);
if (object->events & ((1 << FSCACHE_OBJECT_EV_ERROR) |
(1 << FSCACHE_OBJECT_EV_RELEASE) |
(1 << FSCACHE_OBJECT_EV_RETIRE) |
(1 << FSCACHE_OBJECT_EV_WITHDRAW))) {
_debug("abort init %lx", object->events);
spin_lock(&object->lock);
object->state = FSCACHE_OBJECT_ABORT_INIT;
spin_unlock(&object->lock);
return;
}
spin_lock(&object->cookie->lock);
spin_lock_nested(&object->cookie->parent->lock, 1);
parent = object->parent;
if (!parent) {
_debug("no parent");
set_bit(FSCACHE_OBJECT_EV_WITHDRAW, &object->events);
} else {
spin_lock(&object->lock);
spin_lock_nested(&parent->lock, 1);
_debug("parent %s", fscache_object_states[parent->state]);
if (parent->state >= FSCACHE_OBJECT_DYING) {
_debug("bad parent");
set_bit(FSCACHE_OBJECT_EV_WITHDRAW, &object->events);
} else if (parent->state < FSCACHE_OBJECT_AVAILABLE) {
_debug("wait");
if (list_empty(&object->dep_link)) {
fscache_stat(&fscache_n_cop_grab_object);
object->cache->ops->grab_object(object);
fscache_stat_d(&fscache_n_cop_grab_object);
list_add(&object->dep_link,
&parent->dependents);
if (parent->state == FSCACHE_OBJECT_INIT)
fscache_enqueue_object(parent);
}
} else {
_debug("go");
parent->n_ops++;
parent->n_obj_ops++;
object->lookup_jif = jiffies;
object->state = FSCACHE_OBJECT_LOOKING_UP;
set_bit(FSCACHE_OBJECT_EV_REQUEUE, &object->events);
}
spin_unlock(&parent->lock);
spin_unlock(&object->lock);
}
spin_unlock(&object->cookie->parent->lock);
spin_unlock(&object->cookie->lock);
_leave("");
}
/*
* 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);
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);
}