linux/fs/fscache/object.c
Thomas Gleixner 2874c5fd28 treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152
Based on 1 normalized pattern(s):

  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

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-or-later

has been chosen to replace the boilerplate/reference in 3029 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190527070032.746973796@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-05-30 11:26:32 -07:00

1134 lines
33 KiB
C

// 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;
}