/* 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 "internal.h"
const char *fscache_object_states[] = {
[FSCACHE_OBJECT_INIT] = "OBJECT_INIT",
[FSCACHE_OBJECT_LOOKING_UP] = "OBJECT_LOOKING_UP",
[FSCACHE_OBJECT_CREATING] = "OBJECT_CREATING",
[FSCACHE_OBJECT_AVAILABLE] = "OBJECT_AVAILABLE",
[FSCACHE_OBJECT_ACTIVE] = "OBJECT_ACTIVE",
[FSCACHE_OBJECT_UPDATING] = "OBJECT_UPDATING",
[FSCACHE_OBJECT_DYING] = "OBJECT_DYING",
[FSCACHE_OBJECT_LC_DYING] = "OBJECT_LC_DYING",
[FSCACHE_OBJECT_ABORT_INIT] = "OBJECT_ABORT_INIT",
[FSCACHE_OBJECT_RELEASING] = "OBJECT_RELEASING",
[FSCACHE_OBJECT_RECYCLING] = "OBJECT_RECYCLING",
[FSCACHE_OBJECT_WITHDRAWING] = "OBJECT_WITHDRAWING",
[FSCACHE_OBJECT_DEAD] = "OBJECT_DEAD",
};
EXPORT_SYMBOL(fscache_object_states);
static void fscache_object_slow_work_put_ref(struct slow_work *);
static int fscache_object_slow_work_get_ref(struct slow_work *);
static void fscache_object_slow_work_execute(struct slow_work *);
static void fscache_initialise_object(struct fscache_object *);
static void fscache_lookup_object(struct fscache_object *);
static void fscache_object_available(struct fscache_object *);
static void fscache_release_object(struct fscache_object *);
static void fscache_withdraw_object(struct fscache_object *);
static void fscache_enqueue_dependents(struct fscache_object *);
static void fscache_dequeue_object(struct fscache_object *);
const struct slow_work_ops fscache_object_slow_work_ops = {
.get_ref = fscache_object_slow_work_get_ref,
.put_ref = fscache_object_slow_work_put_ref,
.execute = fscache_object_slow_work_execute,
};
EXPORT_SYMBOL(fscache_object_slow_work_ops);
/*
* 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;
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;
/* update the object metadata on disk */
case FSCACHE_OBJECT_UPDATING:
clear_bit(FSCACHE_OBJECT_EV_UPDATE, &object->events);
fscache_stat(&fscache_n_updates_run);
object->cache->ops->update_object(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);
object->cache->ops->lookup_complete(object);
spin_lock(&object->lock);
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);
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);
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_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();
}
/*
* 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);
clear_bit(FSCACHE_OBJECT_EV_REQUEUE, &object->events);
start = jiffies;
fscache_object_state_machine(object);
fscache_hist(fscache_objs_histogram, start);
if (object->events & object->event_mask)
fscache_enqueue_object(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
* - 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)) {
object->cache->ops->grab_object(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("");
}
/*
* 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
* - 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_lookup_object(struct fscache_object *object)
{
struct fscache_cookie *cookie = object->cookie;
struct fscache_object *parent;
_enter("");
parent = object->parent;
ASSERT(parent != NULL);
ASSERTCMP(parent->n_ops, >, 0);
ASSERTCMP(parent->n_obj_ops, >, 0);
/* make sure the parent is still available */
ASSERTCMP(parent->state, >=, FSCACHE_OBJECT_AVAILABLE);
if (parent->state >= FSCACHE_OBJECT_DYING ||
test_bit(FSCACHE_IOERROR, &object->cache->flags)) {
_debug("unavailable");
set_bit(FSCACHE_OBJECT_EV_WITHDRAW, &object->events);
_leave("");
return;
}
_debug("LOOKUP \"%s/%s\" in \"%s\"",
parent->cookie->def->name, cookie->def->name,
object->cache->tag->name);
fscache_stat(&fscache_n_object_lookups);
object->cache->ops->lookup_object(object);
if (test_bit(FSCACHE_OBJECT_EV_ERROR, &object->events))
set_bit(FSCACHE_COOKIE_UNAVAILABLE, &cookie->flags);
_leave("");
}
/**
* 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, fscache_object_states[object->state]);
spin_lock(&object->lock);
if (object->state == FSCACHE_OBJECT_LOOKING_UP) {
fscache_stat(&fscache_n_object_lookups_negative);
/* transit here to allow write requests to begin stacking up
* and read requests to begin returning ENODATA */
object->state = FSCACHE_OBJECT_CREATING;
spin_unlock(&object->lock);
set_bit(FSCACHE_COOKIE_PENDING_FILL, &cookie->flags);
set_bit(FSCACHE_COOKIE_NO_DATA_YET, &cookie->flags);
_debug("wake up lookup %p", &cookie->flags);
smp_mb__before_clear_bit();
clear_bit(FSCACHE_COOKIE_LOOKING_UP, &cookie->flags);
smp_mb__after_clear_bit();
wake_up_bit(&cookie->flags, FSCACHE_COOKIE_LOOKING_UP);
set_bit(FSCACHE_OBJECT_EV_REQUEUE, &object->events);
} else {
ASSERTCMP(object->state, ==, FSCACHE_OBJECT_CREATING);
spin_unlock(&object->lock);
}
_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, fscache_object_states[object->state]);
/* if we were still looking up, then we must have a positive lookup
* result, in which case there may be data available */
spin_lock(&object->lock);
if (object->state == FSCACHE_OBJECT_LOOKING_UP) {
fscache_stat(&fscache_n_object_lookups_positive);
clear_bit(FSCACHE_COOKIE_NO_DATA_YET, &cookie->flags);
object->state = FSCACHE_OBJECT_AVAILABLE;
spin_unlock(&object->lock);
smp_mb__before_clear_bit();
clear_bit(FSCACHE_COOKIE_LOOKING_UP, &cookie->flags);
smp_mb__after_clear_bit();
wake_up_bit(&cookie->flags, FSCACHE_COOKIE_LOOKING_UP);
set_bit(FSCACHE_OBJECT_EV_REQUEUE, &object->events);
} else {
ASSERTCMP(object->state, ==, FSCACHE_OBJECT_CREATING);
fscache_stat(&fscache_n_object_created);
object->state = FSCACHE_OBJECT_AVAILABLE;
spin_unlock(&object->lock);
set_bit(FSCACHE_OBJECT_EV_REQUEUE, &object->events);
smp_wmb();
}
if (test_and_clear_bit(FSCACHE_COOKIE_CREATING, &cookie->flags))
wake_up_bit(&cookie->flags, FSCACHE_COOKIE_CREATING);
_leave("");
}
EXPORT_SYMBOL(fscache_obtained_object);
/*
* handle an object that has just become available
*/
static void fscache_object_available(struct fscache_object *object)
{
_enter("{OBJ%x}", object->debug_id);
spin_lock(&object->lock);
if (test_and_clear_bit(FSCACHE_COOKIE_CREATING, &object->cookie->flags))
wake_up_bit(&object->cookie->flags, FSCACHE_COOKIE_CREATING);
fscache_done_parent_op(object);
if (object->n_in_progress == 0) {
if (object->n_ops > 0) {
ASSERTCMP(object->n_ops, >=, object->n_obj_ops);
ASSERTIF(object->n_ops > object->n_obj_ops,
!list_empty(&object->pending_ops));
fscache_start_operations(object);
} else {
ASSERT(list_empty(&object->pending_ops));
}
}
spin_unlock(&object->lock);
object->cache->ops->lookup_complete(object);
fscache_enqueue_dependents(object);
fscache_hist(fscache_obj_instantiate_histogram, object->lookup_jif);
fscache_stat(&fscache_n_object_avail);
_leave("");
}
/*
* drop an object's attachments
*/
static void fscache_drop_object(struct fscache_object *object)
{
struct fscache_object *parent = object->parent;
struct fscache_cache *cache = object->cache;
_enter("{OBJ%x,%d}", object->debug_id, object->n_children);
spin_lock(&cache->object_list_lock);
list_del_init(&object->cache_link);
spin_unlock(&cache->object_list_lock);
cache->ops->drop_object(object);
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 slow work processor */
object->cache->ops->put_object(object);
_leave("");
}
/*
* release or recycle an object that the netfs has discarded
*/
static void fscache_release_object(struct fscache_object *object)
{
_enter("");
fscache_drop_object(object);
}
/*
* withdraw an object from active service
*/
static void fscache_withdraw_object(struct fscache_object *object)
{
struct fscache_cookie *cookie;
bool detached;
_enter("");
spin_lock(&object->lock);
cookie = object->cookie;
if (cookie) {
/* need to get the cookie lock before the object lock, starting
* from the object pointer */
atomic_inc(&cookie->usage);
spin_unlock(&object->lock);
detached = false;
spin_lock(&cookie->lock);
spin_lock(&object->lock);
if (object->cookie == cookie) {
hlist_del_init(&object->cookie_link);
object->cookie = NULL;
detached = true;
}
spin_unlock(&cookie->lock);
fscache_cookie_put(cookie);
if (detached)
fscache_cookie_put(cookie);
}
spin_unlock(&object->lock);
fscache_drop_object(object);
}
/*
* withdraw an object from active service at the behest of the cache
* - need break the links to a cached object cookie
* - called under two situations:
* (1) recycler decides to reclaim an in-use object
* (2) a cache is unmounted
* - have to take care as the cookie can be being relinquished by the netfs
* simultaneously
* - the object is pinned by the caller holding a refcount on it
*/
void fscache_withdrawing_object(struct fscache_cache *cache,
struct fscache_object *object)
{
bool enqueue = false;
_enter(",OBJ%x", object->debug_id);
spin_lock(&object->lock);
if (object->state < FSCACHE_OBJECT_WITHDRAWING) {
object->state = FSCACHE_OBJECT_WITHDRAWING;
enqueue = true;
}
spin_unlock(&object->lock);
if (enqueue)
fscache_enqueue_object(object);
_leave("");
}
/*
* allow the slow work item processor to get a ref on an object
*/
static int fscache_object_slow_work_get_ref(struct slow_work *work)
{
struct fscache_object *object =
container_of(work, struct fscache_object, work);
return object->cache->ops->grab_object(object) ? 0 : -EAGAIN;
}
/*
* allow the slow work item processor to discard a ref on a work item
*/
static void fscache_object_slow_work_put_ref(struct slow_work *work)
{
struct fscache_object *object =
container_of(work, struct fscache_object, work);
return object->cache->ops->put_object(object);
}
/*
* enqueue an object for metadata-type processing
*/
void fscache_enqueue_object(struct fscache_object *object)
{
_enter("{OBJ%x}", object->debug_id);
slow_work_enqueue(&object->work);
}
/*
* enqueue the dependents of an object for metadata-type processing
* - the caller must hold the object's lock
* - this may cause an already locked object to wind up being processed again
*/
static void fscache_enqueue_dependents(struct fscache_object *object)
{
struct fscache_object *dep;
_enter("{OBJ%x}", object->debug_id);
if (list_empty(&object->dependents))
return;
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);
/* sort onto appropriate lists */
fscache_enqueue_object(dep);
dep->cache->ops->put_object(dep);
if (!list_empty(&object->dependents))
cond_resched_lock(&object->lock);
}
spin_unlock(&object->lock);
}
/*
* remove an object from whatever queue it's waiting on
* - the caller must hold object->lock
*/
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
*/
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);
