* 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
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
*/
}
/*
+ * 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)
+{
+ struct fscache_cookie *cookie;
+
+ BUG_ON(!def);
+
+ _enter("{%s},{%s},%p",
+ parent ? (char *) parent->def->name : "<no-parent>",
+ def->name, netfs_data);
+
+ 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);
+
+ atomic_inc(&parent->usage);
+ atomic_inc(&parent->n_children);
+
+ cookie->def = def;
+ cookie->parent = parent;
+ cookie->netfs_data = netfs_data;
+ cookie->flags = 0;
+
+ INIT_RADIX_TREE(&cookie->stores, GFP_NOFS);
+
+ 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 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) {
+ atomic_dec(&parent->n_children);
+ __fscache_cookie_put(cookie);
+ fscache_stat(&fscache_n_acquires_nobufs);
+ _leave(" = NULL");
+ return NULL;
+ }
+ }
+
+ fscache_stat(&fscache_n_acquires_ok);
+ _leave(" = %p", cookie);
+ return cookie;
+}
+EXPORT_SYMBOL(__fscache_acquire_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("");
+
+ cookie->flags = 1 << FSCACHE_COOKIE_UNAVAILABLE;
+
+ /* 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);
+
+ cookie->flags =
+ (1 << FSCACHE_COOKIE_LOOKING_UP) |
+ (1 << FSCACHE_COOKIE_CREATING) |
+ (1 << FSCACHE_COOKIE_NO_DATA_YET);
+
+ /* 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_enqueue_object(object);
+
+ 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;
+ struct hlist_node *_n;
+ int ret;
+
+ _enter("%p,%p{%s}", cache, cookie, cookie->def->name);
+
+ spin_lock(&cookie->lock);
+ hlist_for_each_entry(object, _n, &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) */
+ object = cache->ops->alloc_object(cache, cookie);
+ 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)
+ cache->ops->put_object(object);
+
+ _leave(" = 0");
+ return 0;
+
+object_already_extant:
+ ret = -ENOBUFS;
+ if (object->state >= FSCACHE_OBJECT_DYING) {
+ spin_unlock(&cookie->lock);
+ goto error;
+ }
+ spin_unlock(&cookie->lock);
+ _leave(" = 0 [found]");
+ return 0;
+
+error_put:
+ cache->ops->put_object(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;
+ struct hlist_node *_n;
+ 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, _n, &cookie->backing_objects, cookie_link) {
+ if (p->cache == object->cache) {
+ if (p->state >= FSCACHE_OBJECT_DYING)
+ ret = -ENOBUFS;
+ goto cant_attach_object;
+ }
+ }
+
+ /* pin the parent object */
+ spin_lock_nested(&cookie->parent->lock, 1);
+ hlist_for_each_entry(p, _n, &cookie->parent->backing_objects,
+ cookie_link) {
+ if (p->cache == object->cache) {
+ if (p->state >= FSCACHE_OBJECT_DYING) {
+ 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);
+ ret = 0;
+
+cant_attach_object:
+ spin_unlock(&cookie->lock);
+ _leave(" = %d", ret);
+ return ret;
+}
+
+/*
+ * update the index entries backing a cookie
+ */
+void __fscache_update_cookie(struct fscache_cookie *cookie)
+{
+ struct fscache_object *object;
+ struct hlist_node *_p;
+
+ 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);
+
+ /* update the index entry on disk in each cache backing this cookie */
+ hlist_for_each_entry(object, _p,
+ &cookie->backing_objects, cookie_link) {
+ fscache_raise_event(object, FSCACHE_OBJECT_EV_UPDATE);
+ }
+
+ spin_unlock(&cookie->lock);
+ _leave("");
+}
+EXPORT_SYMBOL(__fscache_update_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, int retire)
+{
+ struct fscache_cache *cache;
+ struct fscache_object *object;
+ unsigned long event;
+
+ fscache_stat(&fscache_n_relinquishes);
+
+ if (!cookie) {
+ fscache_stat(&fscache_n_relinquishes_null);
+ _leave(" [no cookie]");
+ return;
+ }
+
+ _enter("%p{%s,%p},%d",
+ cookie, cookie->def->name, cookie->netfs_data, retire);
+
+ if (atomic_read(&cookie->n_children) != 0) {
+ printk(KERN_ERR "FS-Cache: Cookie '%s' still has children\n",
+ cookie->def->name);
+ BUG();
+ }
+
+ /* wait for the cookie to finish being instantiated (or to fail) */
+ if (test_bit(FSCACHE_COOKIE_CREATING, &cookie->flags)) {
+ fscache_stat(&fscache_n_relinquishes_waitcrt);
+ wait_on_bit(&cookie->flags, FSCACHE_COOKIE_CREATING,
+ fscache_wait_bit, TASK_UNINTERRUPTIBLE);
+ }
+
+ event = retire ? FSCACHE_OBJECT_EV_RETIRE : FSCACHE_OBJECT_EV_RELEASE;
+
+ /* detach pointers back to the netfs */
+ spin_lock(&cookie->lock);
+
+ cookie->netfs_data = NULL;
+ cookie->def = NULL;
+
+ /* break links with all the active objects */
+ while (!hlist_empty(&cookie->backing_objects)) {
+ object = hlist_entry(cookie->backing_objects.first,
+ struct fscache_object,
+ cookie_link);
+
+ _debug("RELEASE OBJ%x", object->debug_id);
+
+ /* detach each cache object from the object cookie */
+ spin_lock(&object->lock);
+ hlist_del_init(&object->cookie_link);
+
+ cache = object->cache;
+ object->cookie = NULL;
+ fscache_raise_event(object, event);
+ spin_unlock(&object->lock);
+
+ if (atomic_dec_and_test(&cookie->usage))
+ /* the cookie refcount shouldn't be reduced to 0 yet */
+ BUG();
+ }
+
+ spin_unlock(&cookie->lock);
+
+ if (cookie->parent) {
+ ASSERTCMP(atomic_read(&cookie->parent->usage), >, 0);
+ ASSERTCMP(atomic_read(&cookie->parent->n_children), >, 0);
+ atomic_dec(&cookie->parent->n_children);
+ }
+
+ /* finally dispose of 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)
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff