linux/fs/fscache/cookie.c
David Howells 94d30ae90a FS-Cache: Provide the ability to enable/disable cookies
Provide the ability to enable and disable fscache cookies.  A disabled cookie
will reject or ignore further requests to:

	Acquire a child cookie
	Invalidate and update backing objects
	Check the consistency of a backing object
	Allocate storage for backing page
	Read backing pages
	Write to backing pages

but still allows:

	Checks/waits on the completion of already in-progress objects
	Uncaching of pages
	Relinquishment of cookies

Two new operations are provided:

 (1) Disable a cookie:

	void fscache_disable_cookie(struct fscache_cookie *cookie,
				    bool invalidate);

     If the cookie is not already disabled, this locks the cookie against other
     dis/enablement ops, marks the cookie as being disabled, discards or
     invalidates any backing objects and waits for cessation of activity on any
     associated object.

     This is a wrapper around a chunk split out of fscache_relinquish_cookie(),
     but it reinitialises the cookie such that it can be reenabled.

     All possible failures are handled internally.  The caller should consider
     calling fscache_uncache_all_inode_pages() afterwards to make sure all page
     markings are cleared up.

 (2) Enable a cookie:

	void fscache_enable_cookie(struct fscache_cookie *cookie,
				   bool (*can_enable)(void *data),
				   void *data)

     If the cookie is not already enabled, this locks the cookie against other
     dis/enablement ops, invokes can_enable() and, if the cookie is not an
     index cookie, will begin the procedure of acquiring backing objects.

     The optional can_enable() function is passed the data argument and returns
     a ruling as to whether or not enablement should actually be permitted to
     begin.

     All possible failures are handled internally.  The cookie will only be
     marked as enabled if provisional backing objects are allocated.

A later patch will introduce these to NFS.  Cookie enablement during nfs_open()
is then contingent on i_writecount <= 0.  can_enable() checks for a race
between open(O_RDONLY) and open(O_WRONLY/O_RDWR).  This simplifies NFS's cookie
handling and allows us to get rid of open(O_RDONLY) accidentally introducing
caching to an inode that's open for writing already.

One operation has its API modified:

 (3) Acquire a cookie.

	struct fscache_cookie *fscache_acquire_cookie(
		struct fscache_cookie *parent,
		const struct fscache_cookie_def *def,
		void *netfs_data,
		bool enable);

     This now has an additional argument that indicates whether the requested
     cookie should be enabled by default.  It doesn't need the can_enable()
     function because the caller must prevent multiple calls for the same netfs
     object and it doesn't need to take the enablement lock because no one else
     can get at the cookie before this returns.

Signed-off-by: David Howells <dhowells@redhat.com
2013-09-27 18:40:25 +01:00

724 lines
19 KiB
C

/* netfs cookie management
*
* Copyright (C) 2004-2007 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/netfs-api.txt for more information on
* the netfs API.
*/
#define FSCACHE_DEBUG_LEVEL COOKIE
#include <linux/module.h>
#include <linux/slab.h>
#include "internal.h"
struct kmem_cache *fscache_cookie_jar;
static atomic_t fscache_object_debug_id = ATOMIC_INIT(0);
static int fscache_acquire_non_index_cookie(struct fscache_cookie *cookie);
static int fscache_alloc_object(struct fscache_cache *cache,
struct fscache_cookie *cookie);
static int fscache_attach_object(struct fscache_cookie *cookie,
struct fscache_object *object);
/*
* initialise an cookie jar slab element prior to any use
*/
void fscache_cookie_init_once(void *_cookie)
{
struct fscache_cookie *cookie = _cookie;
memset(cookie, 0, sizeof(*cookie));
spin_lock_init(&cookie->lock);
spin_lock_init(&cookie->stores_lock);
INIT_HLIST_HEAD(&cookie->backing_objects);
}
/*
* request a cookie to represent an object (index, datafile, xattr, etc)
* - parent specifies the parent object
* - the top level index cookie for each netfs is stored in the fscache_netfs
* struct upon registration
* - def points to the definition
* - the netfs_data will be passed to the functions pointed to in *def
* - all attached caches will be searched to see if they contain this object
* - index objects aren't stored on disk until there's a dependent file that
* needs storing
* - other objects are stored in a selected cache immediately, and all the
* indices forming the path to it are instantiated if necessary
* - we never let on to the netfs about errors
* - we may set a negative cookie pointer, but that's okay
*/
struct fscache_cookie *__fscache_acquire_cookie(
struct fscache_cookie *parent,
const struct fscache_cookie_def *def,
void *netfs_data,
bool enable)
{
struct fscache_cookie *cookie;
BUG_ON(!def);
_enter("{%s},{%s},%p,%u",
parent ? (char *) parent->def->name : "<no-parent>",
def->name, netfs_data, enable);
fscache_stat(&fscache_n_acquires);
/* if there's no parent cookie, then we don't create one here either */
if (!parent) {
fscache_stat(&fscache_n_acquires_null);
_leave(" [no parent]");
return NULL;
}
/* validate the definition */
BUG_ON(!def->get_key);
BUG_ON(!def->name[0]);
BUG_ON(def->type == FSCACHE_COOKIE_TYPE_INDEX &&
parent->def->type != FSCACHE_COOKIE_TYPE_INDEX);
/* allocate and initialise a cookie */
cookie = kmem_cache_alloc(fscache_cookie_jar, GFP_KERNEL);
if (!cookie) {
fscache_stat(&fscache_n_acquires_oom);
_leave(" [ENOMEM]");
return NULL;
}
atomic_set(&cookie->usage, 1);
atomic_set(&cookie->n_children, 0);
/* We keep the active count elevated until relinquishment to prevent an
* attempt to wake up every time the object operations queue quiesces.
*/
atomic_set(&cookie->n_active, 1);
atomic_inc(&parent->usage);
atomic_inc(&parent->n_children);
cookie->def = def;
cookie->parent = parent;
cookie->netfs_data = netfs_data;
cookie->flags = (1 << FSCACHE_COOKIE_NO_DATA_YET);
/* radix tree insertion won't use the preallocation pool unless it's
* told it may not wait */
INIT_RADIX_TREE(&cookie->stores, GFP_NOFS & ~__GFP_WAIT);
switch (cookie->def->type) {
case FSCACHE_COOKIE_TYPE_INDEX:
fscache_stat(&fscache_n_cookie_index);
break;
case FSCACHE_COOKIE_TYPE_DATAFILE:
fscache_stat(&fscache_n_cookie_data);
break;
default:
fscache_stat(&fscache_n_cookie_special);
break;
}
if (enable) {
/* if the object is an index then we need do nothing more here
* - we create indices on disk when we need them as an index
* may exist in multiple caches */
if (cookie->def->type != FSCACHE_COOKIE_TYPE_INDEX) {
if (fscache_acquire_non_index_cookie(cookie) == 0) {
set_bit(FSCACHE_COOKIE_ENABLED, &cookie->flags);
} else {
atomic_dec(&parent->n_children);
__fscache_cookie_put(cookie);
fscache_stat(&fscache_n_acquires_nobufs);
_leave(" = NULL");
return NULL;
}
} else {
set_bit(FSCACHE_COOKIE_ENABLED, &cookie->flags);
}
}
fscache_stat(&fscache_n_acquires_ok);
_leave(" = %p", cookie);
return cookie;
}
EXPORT_SYMBOL(__fscache_acquire_cookie);
/*
* Enable a cookie to permit it to accept new operations.
*/
void __fscache_enable_cookie(struct fscache_cookie *cookie,
bool (*can_enable)(void *data),
void *data)
{
_enter("%p", cookie);
wait_on_bit_lock(&cookie->flags, FSCACHE_COOKIE_ENABLEMENT_LOCK,
fscache_wait_bit, TASK_UNINTERRUPTIBLE);
if (test_bit(FSCACHE_COOKIE_ENABLED, &cookie->flags))
goto out_unlock;
if (can_enable && !can_enable(data)) {
/* The netfs decided it didn't want to enable after all */
} else if (cookie->def->type != FSCACHE_COOKIE_TYPE_INDEX) {
/* Wait for outstanding disablement to complete */
__fscache_wait_on_invalidate(cookie);
if (fscache_acquire_non_index_cookie(cookie) == 0)
set_bit(FSCACHE_COOKIE_ENABLED, &cookie->flags);
} else {
set_bit(FSCACHE_COOKIE_ENABLED, &cookie->flags);
}
out_unlock:
clear_bit_unlock(FSCACHE_COOKIE_ENABLEMENT_LOCK, &cookie->flags);
wake_up_bit(&cookie->flags, FSCACHE_COOKIE_ENABLEMENT_LOCK);
}
EXPORT_SYMBOL(__fscache_enable_cookie);
/*
* acquire a non-index cookie
* - this must make sure the index chain is instantiated and instantiate the
* object representation too
*/
static int fscache_acquire_non_index_cookie(struct fscache_cookie *cookie)
{
struct fscache_object *object;
struct fscache_cache *cache;
uint64_t i_size;
int ret;
_enter("");
set_bit(FSCACHE_COOKIE_UNAVAILABLE, &cookie->flags);
/* now we need to see whether the backing objects for this cookie yet
* exist, if not there'll be nothing to search */
down_read(&fscache_addremove_sem);
if (list_empty(&fscache_cache_list)) {
up_read(&fscache_addremove_sem);
_leave(" = 0 [no caches]");
return 0;
}
/* select a cache in which to store the object */
cache = fscache_select_cache_for_object(cookie->parent);
if (!cache) {
up_read(&fscache_addremove_sem);
fscache_stat(&fscache_n_acquires_no_cache);
_leave(" = -ENOMEDIUM [no cache]");
return -ENOMEDIUM;
}
_debug("cache %s", cache->tag->name);
set_bit(FSCACHE_COOKIE_LOOKING_UP, &cookie->flags);
/* ask the cache to allocate objects for this cookie and its parent
* chain */
ret = fscache_alloc_object(cache, cookie);
if (ret < 0) {
up_read(&fscache_addremove_sem);
_leave(" = %d", ret);
return ret;
}
/* pass on how big the object we're caching is supposed to be */
cookie->def->get_attr(cookie->netfs_data, &i_size);
spin_lock(&cookie->lock);
if (hlist_empty(&cookie->backing_objects)) {
spin_unlock(&cookie->lock);
goto unavailable;
}
object = hlist_entry(cookie->backing_objects.first,
struct fscache_object, cookie_link);
fscache_set_store_limit(object, i_size);
/* initiate the process of looking up all the objects in the chain
* (done by fscache_initialise_object()) */
fscache_raise_event(object, FSCACHE_OBJECT_EV_NEW_CHILD);
spin_unlock(&cookie->lock);
/* we may be required to wait for lookup to complete at this point */
if (!fscache_defer_lookup) {
_debug("non-deferred lookup %p", &cookie->flags);
wait_on_bit(&cookie->flags, FSCACHE_COOKIE_LOOKING_UP,
fscache_wait_bit, TASK_UNINTERRUPTIBLE);
_debug("complete");
if (test_bit(FSCACHE_COOKIE_UNAVAILABLE, &cookie->flags))
goto unavailable;
}
up_read(&fscache_addremove_sem);
_leave(" = 0 [deferred]");
return 0;
unavailable:
up_read(&fscache_addremove_sem);
_leave(" = -ENOBUFS");
return -ENOBUFS;
}
/*
* recursively allocate cache object records for a cookie/cache combination
* - caller must be holding the addremove sem
*/
static int fscache_alloc_object(struct fscache_cache *cache,
struct fscache_cookie *cookie)
{
struct fscache_object *object;
int ret;
_enter("%p,%p{%s}", cache, cookie, cookie->def->name);
spin_lock(&cookie->lock);
hlist_for_each_entry(object, &cookie->backing_objects,
cookie_link) {
if (object->cache == cache)
goto object_already_extant;
}
spin_unlock(&cookie->lock);
/* ask the cache to allocate an object (we may end up with duplicate
* objects at this stage, but we sort that out later) */
fscache_stat(&fscache_n_cop_alloc_object);
object = cache->ops->alloc_object(cache, cookie);
fscache_stat_d(&fscache_n_cop_alloc_object);
if (IS_ERR(object)) {
fscache_stat(&fscache_n_object_no_alloc);
ret = PTR_ERR(object);
goto error;
}
fscache_stat(&fscache_n_object_alloc);
object->debug_id = atomic_inc_return(&fscache_object_debug_id);
_debug("ALLOC OBJ%x: %s {%lx}",
object->debug_id, cookie->def->name, object->events);
ret = fscache_alloc_object(cache, cookie->parent);
if (ret < 0)
goto error_put;
/* only attach if we managed to allocate all we needed, otherwise
* discard the object we just allocated and instead use the one
* attached to the cookie */
if (fscache_attach_object(cookie, object) < 0) {
fscache_stat(&fscache_n_cop_put_object);
cache->ops->put_object(object);
fscache_stat_d(&fscache_n_cop_put_object);
}
_leave(" = 0");
return 0;
object_already_extant:
ret = -ENOBUFS;
if (fscache_object_is_dead(object)) {
spin_unlock(&cookie->lock);
goto error;
}
spin_unlock(&cookie->lock);
_leave(" = 0 [found]");
return 0;
error_put:
fscache_stat(&fscache_n_cop_put_object);
cache->ops->put_object(object);
fscache_stat_d(&fscache_n_cop_put_object);
error:
_leave(" = %d", ret);
return ret;
}
/*
* attach a cache object to a cookie
*/
static int fscache_attach_object(struct fscache_cookie *cookie,
struct fscache_object *object)
{
struct fscache_object *p;
struct fscache_cache *cache = object->cache;
int ret;
_enter("{%s},{OBJ%x}", cookie->def->name, object->debug_id);
spin_lock(&cookie->lock);
/* there may be multiple initial creations of this object, but we only
* want one */
ret = -EEXIST;
hlist_for_each_entry(p, &cookie->backing_objects, cookie_link) {
if (p->cache == object->cache) {
if (fscache_object_is_dying(p))
ret = -ENOBUFS;
goto cant_attach_object;
}
}
/* pin the parent object */
spin_lock_nested(&cookie->parent->lock, 1);
hlist_for_each_entry(p, &cookie->parent->backing_objects,
cookie_link) {
if (p->cache == object->cache) {
if (fscache_object_is_dying(p)) {
ret = -ENOBUFS;
spin_unlock(&cookie->parent->lock);
goto cant_attach_object;
}
object->parent = p;
spin_lock(&p->lock);
p->n_children++;
spin_unlock(&p->lock);
break;
}
}
spin_unlock(&cookie->parent->lock);
/* attach to the cache's object list */
if (list_empty(&object->cache_link)) {
spin_lock(&cache->object_list_lock);
list_add(&object->cache_link, &cache->object_list);
spin_unlock(&cache->object_list_lock);
}
/* attach to the cookie */
object->cookie = cookie;
atomic_inc(&cookie->usage);
hlist_add_head(&object->cookie_link, &cookie->backing_objects);
fscache_objlist_add(object);
ret = 0;
cant_attach_object:
spin_unlock(&cookie->lock);
_leave(" = %d", ret);
return ret;
}
/*
* Invalidate an object. Callable with spinlocks held.
*/
void __fscache_invalidate(struct fscache_cookie *cookie)
{
struct fscache_object *object;
_enter("{%s}", cookie->def->name);
fscache_stat(&fscache_n_invalidates);
/* Only permit invalidation of data files. Invalidating an index will
* require the caller to release all its attachments to the tree rooted
* there, and if it's doing that, it may as well just retire the
* cookie.
*/
ASSERTCMP(cookie->def->type, ==, FSCACHE_COOKIE_TYPE_DATAFILE);
/* We will be updating the cookie too. */
BUG_ON(!cookie->def->get_aux);
/* If there's an object, we tell the object state machine to handle the
* invalidation on our behalf, otherwise there's nothing to do.
*/
if (!hlist_empty(&cookie->backing_objects)) {
spin_lock(&cookie->lock);
if (fscache_cookie_enabled(cookie) &&
!hlist_empty(&cookie->backing_objects) &&
!test_and_set_bit(FSCACHE_COOKIE_INVALIDATING,
&cookie->flags)) {
object = hlist_entry(cookie->backing_objects.first,
struct fscache_object,
cookie_link);
if (fscache_object_is_live(object))
fscache_raise_event(
object, FSCACHE_OBJECT_EV_INVALIDATE);
}
spin_unlock(&cookie->lock);
}
_leave("");
}
EXPORT_SYMBOL(__fscache_invalidate);
/*
* Wait for object invalidation to complete.
*/
void __fscache_wait_on_invalidate(struct fscache_cookie *cookie)
{
_enter("%p", cookie);
wait_on_bit(&cookie->flags, FSCACHE_COOKIE_INVALIDATING,
fscache_wait_bit_interruptible,
TASK_UNINTERRUPTIBLE);
_leave("");
}
EXPORT_SYMBOL(__fscache_wait_on_invalidate);
/*
* update the index entries backing a cookie
*/
void __fscache_update_cookie(struct fscache_cookie *cookie)
{
struct fscache_object *object;
fscache_stat(&fscache_n_updates);
if (!cookie) {
fscache_stat(&fscache_n_updates_null);
_leave(" [no cookie]");
return;
}
_enter("{%s}", cookie->def->name);
BUG_ON(!cookie->def->get_aux);
spin_lock(&cookie->lock);
if (fscache_cookie_enabled(cookie)) {
/* update the index entry on disk in each cache backing this
* cookie.
*/
hlist_for_each_entry(object,
&cookie->backing_objects, cookie_link) {
fscache_raise_event(object, FSCACHE_OBJECT_EV_UPDATE);
}
}
spin_unlock(&cookie->lock);
_leave("");
}
EXPORT_SYMBOL(__fscache_update_cookie);
/*
* Disable a cookie to stop it from accepting new requests from the netfs.
*/
void __fscache_disable_cookie(struct fscache_cookie *cookie, bool invalidate)
{
struct fscache_object *object;
bool awaken = false;
_enter("%p,%u", cookie, invalidate);
ASSERTCMP(atomic_read(&cookie->n_active), >, 0);
if (atomic_read(&cookie->n_children) != 0) {
printk(KERN_ERR "FS-Cache: Cookie '%s' still has children\n",
cookie->def->name);
BUG();
}
wait_on_bit_lock(&cookie->flags, FSCACHE_COOKIE_ENABLEMENT_LOCK,
fscache_wait_bit, TASK_UNINTERRUPTIBLE);
if (!test_and_clear_bit(FSCACHE_COOKIE_ENABLED, &cookie->flags))
goto out_unlock_enable;
/* If the cookie is being invalidated, wait for that to complete first
* so that we can reuse the flag.
*/
__fscache_wait_on_invalidate(cookie);
/* Dispose of the backing objects */
set_bit(FSCACHE_COOKIE_INVALIDATING, &cookie->flags);
spin_lock(&cookie->lock);
if (!hlist_empty(&cookie->backing_objects)) {
hlist_for_each_entry(object, &cookie->backing_objects, cookie_link) {
if (invalidate)
set_bit(FSCACHE_OBJECT_RETIRED, &object->flags);
fscache_raise_event(object, FSCACHE_OBJECT_EV_KILL);
}
} else {
if (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);
/* Wait for cessation of activity requiring access to the netfs (when
* n_active reaches 0). This makes sure outstanding reads and writes
* have completed.
*/
if (!atomic_dec_and_test(&cookie->n_active))
wait_on_atomic_t(&cookie->n_active, fscache_wait_atomic_t,
TASK_UNINTERRUPTIBLE);
/* Reset the cookie state if it wasn't relinquished */
if (!test_bit(FSCACHE_COOKIE_RELINQUISHED, &cookie->flags)) {
atomic_inc(&cookie->n_active);
set_bit(FSCACHE_COOKIE_NO_DATA_YET, &cookie->flags);
}
out_unlock_enable:
clear_bit_unlock(FSCACHE_COOKIE_ENABLEMENT_LOCK, &cookie->flags);
wake_up_bit(&cookie->flags, FSCACHE_COOKIE_ENABLEMENT_LOCK);
_leave("");
}
EXPORT_SYMBOL(__fscache_disable_cookie);
/*
* release a cookie back to the cache
* - the object will be marked as recyclable on disk if retire is true
* - all dependents of this cookie must have already been unregistered
* (indices/files/pages)
*/
void __fscache_relinquish_cookie(struct fscache_cookie *cookie, bool retire)
{
fscache_stat(&fscache_n_relinquishes);
if (retire)
fscache_stat(&fscache_n_relinquishes_retire);
if (!cookie) {
fscache_stat(&fscache_n_relinquishes_null);
_leave(" [no cookie]");
return;
}
_enter("%p{%s,%p,%d},%d",
cookie, cookie->def->name, cookie->netfs_data,
atomic_read(&cookie->n_active), retire);
/* No further netfs-accessing operations on this cookie permitted */
set_bit(FSCACHE_COOKIE_RELINQUISHED, &cookie->flags);
__fscache_disable_cookie(cookie, retire);
/* Clear pointers back to the netfs */
cookie->netfs_data = NULL;
cookie->def = NULL;
BUG_ON(cookie->stores.rnode);
if (cookie->parent) {
ASSERTCMP(atomic_read(&cookie->parent->usage), >, 0);
ASSERTCMP(atomic_read(&cookie->parent->n_children), >, 0);
atomic_dec(&cookie->parent->n_children);
}
/* Dispose of the netfs's link to the cookie */
ASSERTCMP(atomic_read(&cookie->usage), >, 0);
fscache_cookie_put(cookie);
_leave("");
}
EXPORT_SYMBOL(__fscache_relinquish_cookie);
/*
* destroy a cookie
*/
void __fscache_cookie_put(struct fscache_cookie *cookie)
{
struct fscache_cookie *parent;
_enter("%p", cookie);
for (;;) {
_debug("FREE COOKIE %p", cookie);
parent = cookie->parent;
BUG_ON(!hlist_empty(&cookie->backing_objects));
kmem_cache_free(fscache_cookie_jar, cookie);
if (!parent)
break;
cookie = parent;
BUG_ON(atomic_read(&cookie->usage) <= 0);
if (!atomic_dec_and_test(&cookie->usage))
break;
}
_leave("");
}
/*
* check the consistency between the netfs inode and the backing cache
*
* NOTE: it only serves no-index type
*/
int __fscache_check_consistency(struct fscache_cookie *cookie)
{
struct fscache_operation *op;
struct fscache_object *object;
bool wake_cookie = false;
int ret;
_enter("%p,", cookie);
ASSERTCMP(cookie->def->type, ==, FSCACHE_COOKIE_TYPE_DATAFILE);
if (fscache_wait_for_deferred_lookup(cookie) < 0)
return -ERESTARTSYS;
if (hlist_empty(&cookie->backing_objects))
return 0;
op = kzalloc(sizeof(*op), GFP_NOIO | __GFP_NOMEMALLOC | __GFP_NORETRY);
if (!op)
return -ENOMEM;
fscache_operation_init(op, NULL, NULL);
op->flags = FSCACHE_OP_MYTHREAD |
(1 << FSCACHE_OP_WAITING) |
(1 << FSCACHE_OP_UNUSE_COOKIE);
spin_lock(&cookie->lock);
if (!fscache_cookie_enabled(cookie) ||
hlist_empty(&cookie->backing_objects))
goto inconsistent;
object = hlist_entry(cookie->backing_objects.first,
struct fscache_object, cookie_link);
if (test_bit(FSCACHE_IOERROR, &object->cache->flags))
goto inconsistent;
op->debug_id = atomic_inc_return(&fscache_op_debug_id);
__fscache_use_cookie(cookie);
if (fscache_submit_op(object, op) < 0)
goto submit_failed;
/* the work queue now carries its own ref on the object */
spin_unlock(&cookie->lock);
ret = fscache_wait_for_operation_activation(object, op,
NULL, NULL, NULL);
if (ret == 0) {
/* ask the cache to honour the operation */
ret = object->cache->ops->check_consistency(op);
fscache_op_complete(op, false);
} else if (ret == -ENOBUFS) {
ret = 0;
}
fscache_put_operation(op);
_leave(" = %d", ret);
return ret;
submit_failed:
wake_cookie = __fscache_unuse_cookie(cookie);
inconsistent:
spin_unlock(&cookie->lock);
if (wake_cookie)
__fscache_wake_unused_cookie(cookie);
kfree(op);
_leave(" = -ESTALE");
return -ESTALE;
}
EXPORT_SYMBOL(__fscache_check_consistency);