linux/fs/fscache/cookie.c
David Howells ec0328e46d fscache: Maintain a catalogue of allocated cookies
Maintain a catalogue of allocated cookies so that cookie collisions can be
handled properly.  For the moment, this just involves printing a warning
and returning a NULL cookie to the caller of fscache_acquire_cookie(), but
in future it might make sense to wait for the old cookie to finish being
cleaned up.

This requires the cookie key to be stored attached to the cookie so that we
still have the key available if the netfs relinquishes the cookie.  This is
done by an earlier patch.

The catalogue also renders redundant fscache_netfs_list (used for checking
for duplicates), so that can be removed.

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Anna Schumaker <anna.schumaker@netapp.com>
Tested-by: Steve Dickson <steved@redhat.com>
2018-04-06 14:05:14 +01:00

975 lines
26 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);
#define fscache_cookie_hash_shift 15
static struct hlist_bl_head fscache_cookie_hash[1 << fscache_cookie_hash_shift];
static int fscache_acquire_non_index_cookie(struct fscache_cookie *cookie,
loff_t object_size);
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);
static void fscache_print_cookie(struct fscache_cookie *cookie, char prefix)
{
struct hlist_node *object;
const u8 *k;
unsigned loop;
pr_err("%c-cookie c=%p [p=%p fl=%lx nc=%u na=%u]\n",
prefix, cookie, cookie->parent, cookie->flags,
atomic_read(&cookie->n_children),
atomic_read(&cookie->n_active));
pr_err("%c-cookie d=%p n=%p\n",
prefix, cookie->def, cookie->netfs_data);
object = READ_ONCE(cookie->backing_objects.first);
if (object)
pr_err("%c-cookie o=%p\n",
prefix, hlist_entry(object, struct fscache_object, cookie_link));
pr_err("%c-key=[%u] '", prefix, cookie->key_len);
k = (cookie->key_len <= sizeof(cookie->inline_key)) ?
cookie->inline_key : cookie->key;
for (loop = 0; loop < cookie->key_len; loop++)
pr_cont("%02x", k[loop]);
pr_cont("'\n");
}
void fscache_free_cookie(struct fscache_cookie *cookie)
{
if (cookie) {
BUG_ON(!hlist_empty(&cookie->backing_objects));
if (cookie->aux_len > sizeof(cookie->inline_aux))
kfree(cookie->aux);
if (cookie->key_len > sizeof(cookie->inline_key))
kfree(cookie->key);
kmem_cache_free(fscache_cookie_jar, cookie);
}
}
/*
* 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);
}
/*
* Set the index key in a cookie. The cookie struct has space for a 12-byte
* key plus length and hash, but if that's not big enough, it's instead a
* pointer to a buffer containing 3 bytes of hash, 1 byte of length and then
* the key data.
*/
static int fscache_set_key(struct fscache_cookie *cookie,
const void *index_key, size_t index_key_len)
{
unsigned long long h;
u32 *buf;
int i;
cookie->key_len = index_key_len;
if (index_key_len > sizeof(cookie->inline_key)) {
buf = kzalloc(index_key_len, GFP_KERNEL);
if (!buf)
return -ENOMEM;
cookie->key = buf;
} else {
buf = (u32 *)cookie->inline_key;
buf[0] = 0;
buf[1] = 0;
buf[2] = 0;
}
memcpy(buf, index_key, index_key_len);
/* Calculate a hash and combine this with the length in the first word
* or first half word
*/
h = (unsigned long)cookie->parent;
h += index_key_len + cookie->type;
for (i = 0; i < (index_key_len + sizeof(u32) - 1) / sizeof(u32); i++)
h += buf[i];
cookie->key_hash = h ^ (h >> 32);
return 0;
}
static long fscache_compare_cookie(const struct fscache_cookie *a,
const struct fscache_cookie *b)
{
const void *ka, *kb;
if (a->key_hash != b->key_hash)
return (long)a->key_hash - (long)b->key_hash;
if (a->parent != b->parent)
return (long)a->parent - (long)b->parent;
if (a->key_len != b->key_len)
return (long)a->key_len - (long)b->key_len;
if (a->type != b->type)
return (long)a->type - (long)b->type;
if (a->key_len <= sizeof(a->inline_key)) {
ka = &a->inline_key;
kb = &b->inline_key;
} else {
ka = a->key;
kb = b->key;
}
return memcmp(ka, kb, a->key_len);
}
/*
* Allocate a cookie.
*/
struct fscache_cookie *fscache_alloc_cookie(
struct fscache_cookie *parent,
const struct fscache_cookie_def *def,
const void *index_key, size_t index_key_len,
const void *aux_data, size_t aux_data_len,
void *netfs_data,
loff_t object_size)
{
struct fscache_cookie *cookie;
/* allocate and initialise a cookie */
cookie = kmem_cache_alloc(fscache_cookie_jar, GFP_KERNEL);
if (!cookie)
return NULL;
cookie->key_len = index_key_len;
cookie->aux_len = aux_data_len;
if (fscache_set_key(cookie, index_key, index_key_len) < 0)
goto nomem;
if (cookie->aux_len <= sizeof(cookie->inline_aux)) {
memcpy(cookie->inline_aux, aux_data, cookie->aux_len);
} else {
cookie->aux = kmemdup(aux_data, cookie->aux_len, GFP_KERNEL);
if (!cookie->aux)
goto nomem;
}
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);
cookie->def = def;
cookie->parent = parent;
cookie->netfs_data = netfs_data;
cookie->flags = (1 << FSCACHE_COOKIE_NO_DATA_YET);
cookie->type = def->type;
/* 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_DIRECT_RECLAIM);
return cookie;
nomem:
fscache_free_cookie(cookie);
return NULL;
}
/*
* Attempt to insert the new cookie into the hash. If there's a collision, we
* return the old cookie if it's not in use and an error otherwise.
*/
struct fscache_cookie *fscache_hash_cookie(struct fscache_cookie *candidate)
{
struct fscache_cookie *cursor;
struct hlist_bl_head *h;
struct hlist_bl_node *p;
unsigned int bucket;
bucket = candidate->key_hash & (ARRAY_SIZE(fscache_cookie_hash) - 1);
h = &fscache_cookie_hash[bucket];
hlist_bl_lock(h);
hlist_bl_for_each_entry(cursor, p, h, hash_link) {
if (fscache_compare_cookie(candidate, cursor) == 0)
goto collision;
}
__set_bit(FSCACHE_COOKIE_ACQUIRED, &candidate->flags);
fscache_cookie_get(candidate->parent, fscache_cookie_get_acquire_parent);
atomic_inc(&candidate->parent->n_children);
hlist_bl_add_head(&candidate->hash_link, h);
hlist_bl_unlock(h);
return candidate;
collision:
if (test_and_set_bit(FSCACHE_COOKIE_ACQUIRED, &cursor->flags)) {
trace_fscache_cookie(cursor, fscache_cookie_collision,
atomic_read(&cursor->usage));
pr_err("Duplicate cookie detected\n");
fscache_print_cookie(cursor, 'O');
fscache_print_cookie(candidate, 'N');
hlist_bl_unlock(h);
return NULL;
}
fscache_cookie_get(cursor, fscache_cookie_get_reacquire);
hlist_bl_unlock(h);
return cursor;
}
/*
* 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,
const void *index_key, size_t index_key_len,
const void *aux_data, size_t aux_data_len,
void *netfs_data,
loff_t object_size,
bool enable)
{
struct fscache_cookie *candidate, *cookie;
BUG_ON(!def);
_enter("{%s},{%s},%p,%u",
parent ? (char *) parent->def->name : "<no-parent>",
def->name, netfs_data, enable);
if (!index_key || !index_key_len || index_key_len > 255 || aux_data_len > 255)
return NULL;
if (!aux_data || !aux_data_len) {
aux_data = NULL;
aux_data_len = 0;
}
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->name[0]);
BUG_ON(def->type == FSCACHE_COOKIE_TYPE_INDEX &&
parent->type != FSCACHE_COOKIE_TYPE_INDEX);
candidate = fscache_alloc_cookie(parent, def,
index_key, index_key_len,
aux_data, aux_data_len,
netfs_data, object_size);
if (!candidate) {
fscache_stat(&fscache_n_acquires_oom);
_leave(" [ENOMEM]");
return NULL;
}
cookie = fscache_hash_cookie(candidate);
if (!cookie) {
trace_fscache_cookie(candidate, fscache_cookie_discard, 1);
goto out;
}
if (cookie == candidate)
candidate = NULL;
switch (cookie->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;
}
trace_fscache_acquire(cookie);
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->type != FSCACHE_COOKIE_TYPE_INDEX) {
if (fscache_acquire_non_index_cookie(cookie, object_size) == 0) {
set_bit(FSCACHE_COOKIE_ENABLED, &cookie->flags);
} else {
atomic_dec(&parent->n_children);
fscache_cookie_put(cookie,
fscache_cookie_put_acquire_nobufs);
fscache_stat(&fscache_n_acquires_nobufs);
_leave(" = NULL");
return NULL;
}
} else {
set_bit(FSCACHE_COOKIE_ENABLED, &cookie->flags);
}
}
fscache_stat(&fscache_n_acquires_ok);
out:
fscache_free_cookie(candidate);
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,
const void *aux_data,
loff_t object_size,
bool (*can_enable)(void *data),
void *data)
{
_enter("%p", cookie);
trace_fscache_enable(cookie);
wait_on_bit_lock(&cookie->flags, FSCACHE_COOKIE_ENABLEMENT_LOCK,
TASK_UNINTERRUPTIBLE);
fscache_update_aux(cookie, aux_data);
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->type != FSCACHE_COOKIE_TYPE_INDEX) {
/* Wait for outstanding disablement to complete */
__fscache_wait_on_invalidate(cookie);
if (fscache_acquire_non_index_cookie(cookie, object_size) == 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,
loff_t object_size)
{
struct fscache_object *object;
struct fscache_cache *cache;
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;
}
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, object_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,
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_obj_put_attach_fail);
fscache_stat_d(&fscache_n_cop_put_object);
}
_leave(" = 0");
return 0;
object_already_extant:
ret = -ENOBUFS;
if (fscache_object_is_dying(object) ||
fscache_cache_is_broken(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_obj_put_alloc_fail);
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;
fscache_cookie_get(cookie, fscache_cookie_get_attach_object);
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->type, ==, FSCACHE_COOKIE_TYPE_DATAFILE);
/* 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,
TASK_UNINTERRUPTIBLE);
_leave("");
}
EXPORT_SYMBOL(__fscache_wait_on_invalidate);
/*
* update the index entries backing a cookie
*/
void __fscache_update_cookie(struct fscache_cookie *cookie, const void *aux_data)
{
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);
spin_lock(&cookie->lock);
fscache_update_aux(cookie, aux_data);
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,
const void *aux_data,
bool invalidate)
{
struct fscache_object *object;
bool awaken = false;
_enter("%p,%u", cookie, invalidate);
trace_fscache_disable(cookie);
ASSERTCMP(atomic_read(&cookie->n_active), >, 0);
if (atomic_read(&cookie->n_children) != 0) {
pr_err("Cookie '%s' still has children\n",
cookie->def->name);
BUG();
}
wait_on_bit_lock(&cookie->flags, FSCACHE_COOKIE_ENABLEMENT_LOCK,
TASK_UNINTERRUPTIBLE);
fscache_update_aux(cookie, aux_data);
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);
clear_bit(FSCACHE_OBJECT_PENDING_WRITE, &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_var_event(&cookie->n_active,
!atomic_read(&cookie->n_active));
}
/* Make sure any pending writes are cancelled. */
if (cookie->type != FSCACHE_COOKIE_TYPE_INDEX)
fscache_invalidate_writes(cookie);
/* 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,
const void *aux_data,
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);
trace_fscache_relinquish(cookie, retire);
/* No further netfs-accessing operations on this cookie permitted */
if (test_and_set_bit(FSCACHE_COOKIE_RELINQUISHED, &cookie->flags))
BUG();
__fscache_disable_cookie(cookie, aux_data, 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, fscache_cookie_put_relinquish);
_leave("");
}
EXPORT_SYMBOL(__fscache_relinquish_cookie);
/*
* Remove a cookie from the hash table.
*/
static void fscache_unhash_cookie(struct fscache_cookie *cookie)
{
struct hlist_bl_head *h;
unsigned int bucket;
bucket = cookie->key_hash & (ARRAY_SIZE(fscache_cookie_hash) - 1);
h = &fscache_cookie_hash[bucket];
hlist_bl_lock(h);
hlist_bl_del(&cookie->hash_link);
hlist_bl_unlock(h);
}
/*
* Drop a reference to a cookie.
*/
void fscache_cookie_put(struct fscache_cookie *cookie,
enum fscache_cookie_trace where)
{
struct fscache_cookie *parent;
int usage;
_enter("%p", cookie);
do {
usage = atomic_dec_return(&cookie->usage);
trace_fscache_cookie(cookie, where, usage);
if (usage > 0)
return;
BUG_ON(usage < 0);
parent = cookie->parent;
fscache_unhash_cookie(cookie);
fscache_free_cookie(cookie);
cookie = parent;
where = fscache_cookie_put_parent;
} while (cookie);
_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,
const void *aux_data)
{
struct fscache_operation *op;
struct fscache_object *object;
bool wake_cookie = false;
int ret;
_enter("%p,", cookie);
ASSERTCMP(cookie->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(cookie, op, NULL, NULL, NULL);
op->flags = FSCACHE_OP_MYTHREAD |
(1 << FSCACHE_OP_WAITING) |
(1 << FSCACHE_OP_UNUSE_COOKIE);
trace_fscache_page_op(cookie, NULL, op, fscache_page_op_check_consistency);
spin_lock(&cookie->lock);
fscache_update_aux(cookie, aux_data);
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);
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);