/*
* 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);
}
/*
* 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_ops--;
parent->n_obj_ops--;
if (parent->n_ops == 0)
fscache_raise_event(parent, FSCACHE_OBJECT_EV_CLEARED);
spin_unlock(&parent->lock);
}
/*
* process events that have been sent to an object's state machine
* - initiates parent lookup
* - does object lookup
* - does object creation
* - does object recycling and retirement
* - does object withdrawal
*/
static void fscache_object_state_machine(struct fscache_object *object)
{
enum fscache_object_state new_state;
struct fscache_cookie *cookie;
ASSERT(object != NULL);
_enter("{OBJ%x,%s,%lx}",
object->debug_id, fscache_object_states[object->state],
object->events);
switch (object->state) {
/* wait for the parent object to become ready */
case FSCACHE_OBJECT_INIT:
object->event_mask =
ULONG_MAX & ~(1 << FSCACHE_OBJECT_EV_CLEARED);
fscache_initialise_object(object);
goto done;
/* look up the object metadata on disk */
case FSCACHE_OBJECT_LOOKING_UP:
fscache_lookup_object(object);
goto lookup_transit;
/* create the object metadata on disk */
case FSCACHE_OBJECT_CREATING:
fscache_lookup_object(object);
goto lookup_transit;
/* handle an object becoming available; start pending
* operations and queue dependent operations for processing */
case FSCACHE_OBJECT_AVAILABLE:
fscache_object_available(object);
goto active_transit;
/* normal running state */
case FSCACHE_OBJECT_ACTIVE:
goto active_transit;
/* Invalidate an object on disk */
case FSCACHE_OBJECT_INVALIDATING:
clear_bit(FSCACHE_OBJECT_EV_INVALIDATE, &object->events);
fscache_stat(&fscache_n_invalidates_run);
fscache_stat(&fscache_n_cop_invalidate_object);
fscache_invalidate_object(object);
fscache_stat_d(&fscache_n_cop_invalidate_object);
fscache_raise_event(object, FSCACHE_OBJECT_EV_UPDATE);
goto active_transit;
/* update the object metadata on disk */
case FSCACHE_OBJECT_UPDATING:
clear_bit(FSCACHE_OBJECT_EV_UPDATE, &object->events);
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);
goto active_transit;
/* handle an object dying during lookup or creation */
case FSCACHE_OBJECT_LC_DYING:
object->event_mask &= ~(1 << FSCACHE_OBJECT_EV_UPDATE);
fscache_stat(&fscache_n_cop_lookup_complete);
object->cache->ops->lookup_complete(object);
fscache_stat_d(&fscache_n_cop_lookup_complete);
spin_lock(&object->lock);
object->state = FSCACHE_OBJECT_DYING;
cookie = object->cookie;
if (cookie) {
if (test_and_clear_bit(FSCACHE_COOKIE_LOOKING_UP,
&cookie->flags))
wake_up_bit(&cookie->flags,
FSCACHE_COOKIE_LOOKING_UP);
if (test_and_clear_bit(FSCACHE_COOKIE_CREATING,
&cookie->flags))
wake_up_bit(&cookie->flags,
FSCACHE_COOKIE_CREATING);
}
spin_unlock(&object->lock);
fscache_done_parent_op(object);
/* wait for completion of all active operations on this object
* and the death of all child objects of this object */
case FSCACHE_OBJECT_DYING:
dying:
clear_bit(FSCACHE_OBJECT_EV_CLEARED, &object->events);
spin_lock(&object->lock);
_debug("dying OBJ%x {%d,%d}",
object->debug_id, object->n_ops, object->n_children);
if (object->n_ops == 0 && object->n_children == 0) {
object->event_mask &=
~(1 << FSCACHE_OBJECT_EV_CLEARED);
object->event_mask |=
(1 << FSCACHE_OBJECT_EV_WITHDRAW) |
(1 << FSCACHE_OBJECT_EV_RETIRE) |
(1 << FSCACHE_OBJECT_EV_RELEASE) |
(1 << FSCACHE_OBJECT_EV_ERROR);
} else {
object->event_mask &=
~((1 << FSCACHE_OBJECT_EV_WITHDRAW) |
(1 << FSCACHE_OBJECT_EV_RETIRE) |
(1 << FSCACHE_OBJECT_EV_RELEASE) |
(1 << FSCACHE_OBJECT_EV_ERROR));
object->event_mask |=
1 << FSCACHE_OBJECT_EV_CLEARED;
}
spin_unlock(&object->lock);
fscache_enqueue_dependents(object);
fscache_start_operations(object);
goto terminal_transit;
/* handle an abort during initialisation */
case FSCACHE_OBJECT_ABORT_INIT:
_debug("handle abort init %lx", object->events);
object->event_mask &= ~(1 << FSCACHE_OBJECT_EV_UPDATE);
spin_lock(&object->lock);
fscache_dequeue_object(object);
object->state = FSCACHE_OBJECT_DYING;
if (test_and_clear_bit(FSCACHE_COOKIE_CREATING,
&object->cookie->flags))
wake_up_bit(&object->cookie->flags,
FSCACHE_COOKIE_CREATING);
spin_unlock(&object->lock);
goto dying;
/* handle the netfs releasing an object and possibly marking it
* obsolete too */
case FSCACHE_OBJECT_RELEASING:
case FSCACHE_OBJECT_RECYCLING:
object->event_mask &=
~((1 << FSCACHE_OBJECT_EV_WITHDRAW) |
(1 << FSCACHE_OBJECT_EV_RETIRE) |
(1 << FSCACHE_OBJECT_EV_RELEASE) |
(1 << FSCACHE_OBJECT_EV_ERROR));
fscache_release_object(object);
spin_lock(&object->lock);
object->state = FSCACHE_OBJECT_DEAD;
spin_unlock(&object->lock);
fscache_stat(&fscache_n_object_dead);
goto terminal_transit;
/* handle the parent cache of this object being withdrawn from
* active service */
case FSCACHE_OBJECT_WITHDRAWING:
object->event_mask &=
~((1 << FSCACHE_OBJECT_EV_WITHDRAW) |
(1 << FSCACHE_OBJECT_EV_RETIRE) |
(1 << FSCACHE_OBJECT_EV_RELEASE) |
(1 << FSCACHE_OBJECT_EV_ERROR));
fscache_withdraw_object(object);
spin_lock(&object->lock);
object->state = FSCACHE_OBJECT_DEAD;
spin_unlock(&object->lock);
fscache_stat(&fscache_n_object_dead);
goto terminal_transit;
/* complain about the object being woken up once it is
* deceased */
case FSCACHE_OBJECT_DEAD:
printk(KERN_ERR "FS-Cache:"
" Unexpected event in dead state %lx\n",
object->events & object->event_mask);
BUG();
default:
printk(KERN_ERR "FS-Cache: Unknown object state %u\n",
object->state);
BUG();
}
/* determine the transition from a lookup state */
lookup_transit:
switch (fls(object->events & object->event_mask) - 1) {
case FSCACHE_OBJECT_EV_WITHDRAW:
case FSCACHE_OBJECT_EV_RETIRE:
case FSCACHE_OBJECT_EV_RELEASE:
case FSCACHE_OBJECT_EV_ERROR:
new_state = FSCACHE_OBJECT_LC_DYING;
goto change_state;
case FSCACHE_OBJECT_EV_REQUEUE:
goto done;
case -1:
goto done; /* sleep until event */
default:
goto unsupported_event;
}
/* determine the transition from an active state */
active_transit:
switch (fls(object->events & object->event_mask) - 1) {
case FSCACHE_OBJECT_EV_WITHDRAW:
case FSCACHE_OBJECT_EV_RETIRE:
case FSCACHE_OBJECT_EV_RELEASE:
case FSCACHE_OBJECT_EV_ERROR:
new_state = FSCACHE_OBJECT_DYING;
goto change_state;
case FSCACHE_OBJECT_EV_INVALIDATE:
new_state = FSCACHE_OBJECT_INVALIDATING;
goto change_state;
case FSCACHE_OBJECT_EV_UPDATE:
new_state = FSCACHE_OBJECT_UPDATING;
goto change_state;
case -1:
new_state = FSCACHE_OBJECT_ACTIVE;
goto change_state; /* sleep until event */
default:
goto unsupported_event;
}
/* determine the transition from a terminal state */
terminal_transit:
switch (fls(object->events & object->event_mask) - 1) {
case FSCACHE_OBJECT_EV_WITHDRAW:
new_state = FSCACHE_OBJECT_WITHDRAWING;
goto change_state;
case FSCACHE_OBJECT_EV_RETIRE:
new_state = FSCACHE_OBJECT_RECYCLING;
goto change_state;
case FSCACHE_OBJECT_EV_RELEASE:
new_state = FSCACHE_OBJECT_RELEASING;
goto change_state;
case FSCACHE_OBJECT_EV_ERROR:
new_state = FSCACHE_OBJECT_WITHDRAWING;
goto change_state;
case FSCACHE_OBJECT_EV_CLEARED:
new_state = FSCACHE_OBJECT_DYING;
goto change_state;
case -1:
goto done; /* sleep until event */
default:
goto unsupported_event;
}
change_state:
spin_lock(&object->lock);
object->state = new_state;
spin_unlock(&object->lock);
done:
_leave(" [->%s]", fscache_object_states[object->state]);
return;
unsupported_event:
printk(KERN_ERR "FS-Cache:"
" Unsupported event %lx [mask %lx] in state %s\n",
object->events, object->event_mask,
fscache_object_states[object->state]);
BUG();
}
