--- /dev/null
+/* cookie.c: general filesystem cache cookie management
+ *
+ * Copyright (C) 2004-5 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.
+ */
+
+#include <linux/module.h>
+#include "fscache-int.h"
+
+static LIST_HEAD(fscache_cache_tag_list);
+static LIST_HEAD(fscache_cache_list);
+static LIST_HEAD(fscache_netfs_list);
+static DECLARE_RWSEM(fscache_addremove_sem);
+static struct fscache_cache_tag fscache_nomem_tag;
+
+kmem_cache_t *fscache_cookie_jar;
+
+static void fscache_withdraw_object(struct fscache_cache *cache,
+ struct fscache_object *object);
+
+static void __fscache_cookie_put(struct fscache_cookie *cookie);
+
+static inline void fscache_cookie_put(struct fscache_cookie *cookie)
+{
+ /* check to see whether the cookie has already been released by looking
+ * for the poison when slab debugging is on */
+#ifdef CONFIG_DEBUG_SLAB
+ BUG_ON((atomic_read(&cookie->usage) & 0xffff0000) == 0x6b6b0000);
+#endif
+
+ BUG_ON(atomic_read(&cookie->usage) <= 0);
+
+ if (atomic_dec_and_test(&cookie->usage))
+ __fscache_cookie_put(cookie);
+
+}
+
+/*****************************************************************************/
+/*
+ * look up a cache tag
+ */
+struct fscache_cache_tag *__fscache_lookup_cache_tag(const char *name)
+{
+ struct fscache_cache_tag *tag, *xtag;
+
+ /* firstly check for the existence of the tag under read lock */
+ down_read(&fscache_addremove_sem);
+
+ list_for_each_entry(tag, &fscache_cache_tag_list, link) {
+ if (strcmp(tag->name, name) == 0) {
+ atomic_inc(&tag->usage);
+ up_read(&fscache_addremove_sem);
+ return tag;
+ }
+ }
+
+ up_read(&fscache_addremove_sem);
+
+ /* the tag does not exist - create a candidate */
+ xtag = kmalloc(sizeof(*xtag) + strlen(name) + 1, GFP_KERNEL);
+ if (!xtag)
+ /* return a dummy tag if out of memory */
+ return &fscache_nomem_tag;
+
+ atomic_set(&xtag->usage, 1);
+ strcpy(xtag->name, name);
+
+ /* write lock, search again and add if still not present */
+ down_write(&fscache_addremove_sem);
+
+ list_for_each_entry(tag, &fscache_cache_tag_list, link) {
+ if (strcmp(tag->name, name) == 0) {
+ atomic_inc(&tag->usage);
+ up_write(&fscache_addremove_sem);
+ kfree(xtag);
+ return tag;
+ }
+ }
+
+ list_add_tail(&xtag->link, &fscache_cache_tag_list);
+ up_write(&fscache_addremove_sem);
+ return xtag;
+}
+
+/*****************************************************************************/
+/*
+ * release a reference to a cache tag
+ */
+void __fscache_release_cache_tag(struct fscache_cache_tag *tag)
+{
+ if (tag != &fscache_nomem_tag) {
+ down_write(&fscache_addremove_sem);
+
+ if (atomic_dec_and_test(&tag->usage))
+ list_del_init(&tag->link);
+ else
+ tag = NULL;
+
+ up_write(&fscache_addremove_sem);
+
+ kfree(tag);
+ }
+}
+
+/*****************************************************************************/
+/*
+ * register a network filesystem for caching
+ */
+int __fscache_register_netfs(struct fscache_netfs *netfs)
+{
+ struct fscache_netfs *ptr;
+ int ret;
+
+ _enter("{%s}", netfs->name);
+
+ INIT_LIST_HEAD(&netfs->link);
+
+ /* allocate a cookie for the primary index */
+ netfs->primary_index =
+ kmem_cache_zalloc(fscache_cookie_jar, SLAB_KERNEL);
+
+ if (!netfs->primary_index) {
+ _leave(" = -ENOMEM");
+ return -ENOMEM;
+ }
+
+ /* initialise the primary index cookie */
+ atomic_set(&netfs->primary_index->usage, 1);
+ atomic_set(&netfs->primary_index->children, 0);
+
+ netfs->primary_index->def = &fscache_fsdef_netfs_def;
+ netfs->primary_index->parent = &fscache_fsdef_index;
+ netfs->primary_index->netfs = netfs;
+ netfs->primary_index->netfs_data = netfs;
+
+ atomic_inc(&netfs->primary_index->parent->usage);
+ atomic_inc(&netfs->primary_index->parent->children);
+
+ init_rwsem(&netfs->primary_index->sem);
+ INIT_HLIST_HEAD(&netfs->primary_index->backing_objects);
+
+ /* check the netfs type is not already present */
+ down_write(&fscache_addremove_sem);
+
+ ret = -EEXIST;
+ list_for_each_entry(ptr, &fscache_netfs_list, link) {
+ if (strcmp(ptr->name, netfs->name) == 0)
+ goto already_registered;
+ }
+
+ list_add(&netfs->link, &fscache_netfs_list);
+ ret = 0;
+
+ printk("FS-Cache: netfs '%s' registered for caching\n", netfs->name);
+
+already_registered:
+ up_write(&fscache_addremove_sem);
+
+ if (ret < 0) {
+ netfs->primary_index->parent = NULL;
+ __fscache_cookie_put(netfs->primary_index);
+ netfs->primary_index = NULL;
+ }
+
+ _leave(" = %d", ret);
+ return ret;
+}
+
+EXPORT_SYMBOL(__fscache_register_netfs);
+
+/*****************************************************************************/
+/*
+ * unregister a network filesystem from the cache
+ * - all cookies must have been released first
+ */
+void __fscache_unregister_netfs(struct fscache_netfs *netfs)
+{
+ _enter("{%s.%u}", netfs->name, netfs->version);
+
+ down_write(&fscache_addremove_sem);
+
+ list_del(&netfs->link);
+ fscache_relinquish_cookie(netfs->primary_index, 0);
+
+ up_write(&fscache_addremove_sem);
+
+ printk("FS-Cache: netfs '%s' unregistered from caching\n",
+ netfs->name);
+
+ _leave("");
+}
+
+EXPORT_SYMBOL(__fscache_unregister_netfs);
+
+/*****************************************************************************/
+/*
+ * initialise a cache record
+ */
+void fscache_init_cache(struct fscache_cache *cache,
+ struct fscache_cache_ops *ops,
+ const char *idfmt,
+ ...)
+{
+ va_list va;
+
+ memset(cache, 0, sizeof(*cache));
+
+ cache->ops = ops;
+
+ va_start(va, idfmt);
+ vsnprintf(cache->identifier, sizeof(cache->identifier), idfmt, va);
+ va_end(va);
+
+ INIT_LIST_HEAD(&cache->link);
+ INIT_LIST_HEAD(&cache->object_list);
+ spin_lock_init(&cache->object_list_lock);
+ init_rwsem(&cache->withdrawal_sem);
+}
+
+EXPORT_SYMBOL(fscache_init_cache);
+
+/*****************************************************************************/
+/*
+ * declare a mounted cache as being open for business
+ */
+int fscache_add_cache(struct fscache_cache *cache,
+ struct fscache_object *ifsdef,
+ const char *tagname)
+{
+ struct fscache_cache_tag *tag;
+
+ BUG_ON(!cache->ops);
+ BUG_ON(!ifsdef);
+
+ cache->flags = 0;
+
+ if (!tagname)
+ tagname = cache->identifier;
+
+ BUG_ON(!tagname[0]);
+
+ _enter("{%s.%s},,%s", cache->ops->name, cache->identifier, tagname);
+
+ if (!cache->ops->grab_object(ifsdef))
+ BUG();
+
+ ifsdef->cookie = &fscache_fsdef_index;
+ ifsdef->cache = cache;
+ cache->fsdef = ifsdef;
+
+ down_write(&fscache_addremove_sem);
+
+ /* instantiate or allocate a cache tag */
+ list_for_each_entry(tag, &fscache_cache_tag_list, link) {
+ if (strcmp(tag->name, tagname) == 0) {
+ if (tag->cache) {
+ printk(KERN_ERR
+ "FS-Cache: cache tag '%s' already in use\n",
+ tagname);
+ up_write(&fscache_addremove_sem);
+ return -EEXIST;
+ }
+
+ atomic_inc(&tag->usage);
+ goto found_cache_tag;
+ }
+ }
+
+ tag = kmalloc(sizeof(*tag) + strlen(tagname) + 1, GFP_KERNEL);
+ if (!tag) {
+ up_write(&fscache_addremove_sem);
+ return -ENOMEM;
+ }
+
+ atomic_set(&tag->usage, 1);
+ strcpy(tag->name, tagname);
+ list_add_tail(&tag->link, &fscache_cache_tag_list);
+
+found_cache_tag:
+ tag->cache = cache;
+ cache->tag = tag;
+
+ /* add the cache to the list */
+ list_add(&cache->link, &fscache_cache_list);
+
+ /* add the cache's netfs definition index object to the cache's
+ * list */
+ spin_lock(&cache->object_list_lock);
+ list_add_tail(&ifsdef->cache_link, &cache->object_list);
+ spin_unlock(&cache->object_list_lock);
+
+ /* add the cache's netfs definition index object to the top level index
+ * cookie as a known backing object */
+ down_write(&fscache_fsdef_index.sem);
+
+ hlist_add_head(&ifsdef->cookie_link,
+ &fscache_fsdef_index.backing_objects);
+
+ atomic_inc(&fscache_fsdef_index.usage);
+
+ /* done */
+ up_write(&fscache_fsdef_index.sem);
+ up_write(&fscache_addremove_sem);
+
+ printk(KERN_NOTICE
+ "FS-Cache: Cache \"%s\" added (type %s)\n",
+ cache->tag->name, cache->ops->name);
+
+ _leave(" = 0 [%s]", cache->identifier);
+ return 0;
+}
+
+EXPORT_SYMBOL(fscache_add_cache);
+
+/*****************************************************************************/
+/*
+ * note a cache I/O error
+ */
+void fscache_io_error(struct fscache_cache *cache)
+{
+ set_bit(FSCACHE_IOERROR, &cache->flags);
+
+ printk(KERN_ERR "FS-Cache: Cache %s stopped due to I/O error\n",
+ cache->ops->name);
+}
+
+EXPORT_SYMBOL(fscache_io_error);
+
+/*****************************************************************************/
+/*
+ * withdraw an unmounted cache from the active service
+ */
+void fscache_withdraw_cache(struct fscache_cache *cache)
+{
+ struct fscache_object *object;
+
+ _enter("");
+
+ printk(KERN_NOTICE
+ "FS-Cache: Withdrawing cache \"%s\"\n",
+ cache->tag->name);
+
+ /* make the cache unavailable for cookie acquisition */
+ down_write(&cache->withdrawal_sem);
+
+ down_write(&fscache_addremove_sem);
+ list_del_init(&cache->link);
+ cache->tag->cache = NULL;
+ up_write(&fscache_addremove_sem);
+
+ /* mark all objects as being withdrawn */
+ spin_lock(&cache->object_list_lock);
+ list_for_each_entry(object, &cache->object_list, cache_link) {
+ set_bit(FSCACHE_OBJECT_WITHDRAWN, &object->flags);
+ }
+ spin_unlock(&cache->object_list_lock);
+
+ /* make sure all pages pinned by operations on behalf of the netfs are
+ * written to disc */
+ cache->ops->sync_cache(cache);
+
+ /* dissociate all the netfs pages backed by this cache from the block
+ * mappings in the cache */
+ cache->ops->dissociate_pages(cache);
+
+ /* we now have to destroy all the active objects pertaining to this
+ * cache */
+ spin_lock(&cache->object_list_lock);
+
+ while (!list_empty(&cache->object_list)) {
+ object = list_entry(cache->object_list.next,
+ struct fscache_object, cache_link);
+ list_del_init(&object->cache_link);
+ spin_unlock(&cache->object_list_lock);
+
+ _debug("withdraw %p", object->cookie);
+
+ /* we've extracted an active object from the tree - now dispose
+ * of it */
+ fscache_withdraw_object(cache, object);
+
+ spin_lock(&cache->object_list_lock);
+ }
+
+ spin_unlock(&cache->object_list_lock);
+
+ fscache_release_cache_tag(cache->tag);
+ cache->tag = NULL;
+
+ _leave("");
+}
+
+EXPORT_SYMBOL(fscache_withdraw_cache);
+
+/*****************************************************************************/
+/*
+ * 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 active object is pinned by the caller holding a refcount on it
+ */
+static void fscache_withdraw_object(struct fscache_cache *cache,
+ struct fscache_object *object)
+{
+ struct fscache_cookie *cookie, *xcookie = NULL;
+
+ _enter(",%p", object);
+
+ /* first of all we have to break the links between the object and the
+ * cookie
+ * - we have to hold both semaphores BUT we have to get the cookie sem
+ * FIRST
+ */
+ cache->ops->lock_object(object);
+
+ cookie = object->cookie;
+ if (cookie) {
+ /* pin the cookie so that is doesn't escape */
+ atomic_inc(&cookie->usage);
+
+ /* re-order the locks to avoid deadlock */
+ cache->ops->unlock_object(object);
+ down_write(&cookie->sem);
+ cache->ops->lock_object(object);
+
+ /* erase references from the object to the cookie */
+ hlist_del_init(&object->cookie_link);
+
+ xcookie = object->cookie;
+ object->cookie = NULL;
+
+ up_write(&cookie->sem);
+ }
+
+ cache->ops->unlock_object(object);
+
+ /* we've broken the links between cookie and object */
+ if (xcookie) {
+ fscache_cookie_put(xcookie);
+ cache->ops->put_object(object);
+ }
+
+ /* unpin the cookie */
+ if (cookie) {
+ if (cookie->def && cookie->def->now_uncached)
+ cookie->def->now_uncached(cookie->netfs_data);
+ fscache_cookie_put(cookie);
+ }
+
+ _leave("");
+}
+
+/*****************************************************************************/
+/*
+ * select a cache on which to store an object
+ * - the cache addremove semaphore must be at least read-locked by the caller
+ * - the object will never be an index
+ */
+static struct fscache_cache *fscache_select_cache_for_object(struct fscache_cookie *cookie)
+{
+ struct fscache_cache_tag *tag;
+ struct fscache_object *object;
+ struct fscache_cache *cache;
+
+ _enter("");
+
+ if (list_empty(&fscache_cache_list)) {
+ _leave(" = NULL [no cache]");
+ return NULL;
+ }
+
+ /* we check the parent to determine the cache to use */
+ down_read(&cookie->parent->sem);
+
+ /* the first in the parent's backing list should be the preferred
+ * cache */
+ if (!hlist_empty(&cookie->parent->backing_objects)) {
+ object = hlist_entry(cookie->parent->backing_objects.first,
+ struct fscache_object, cookie_link);
+
+ cache = object->cache;
+ if (test_bit(FSCACHE_IOERROR, &cache->flags))
+ cache = NULL;
+
+ up_read(&cookie->parent->sem);
+ _leave(" = %p [parent]", cache);
+ return cache;
+ }
+
+ /* the parent is unbacked */
+ if (cookie->parent->def->type != FSCACHE_COOKIE_TYPE_INDEX) {
+ /* parent not an index and is unbacked */
+ up_read(&cookie->parent->sem);
+ _leave(" = NULL [parent ubni]");
+ return NULL;
+ }
+
+ up_read(&cookie->parent->sem);
+
+ if (!cookie->parent->def->select_cache)
+ goto no_preference;
+
+ /* ask the netfs for its preference */
+ tag = cookie->parent->def->select_cache(
+ cookie->parent->parent->netfs_data,
+ cookie->parent->netfs_data);
+
+ if (!tag)
+ goto no_preference;
+
+ if (tag == &fscache_nomem_tag) {
+ _leave(" = NULL [nomem tag]");
+ return NULL;
+ }
+
+ if (!tag->cache) {
+ _leave(" = NULL [unbacked tag]");
+ return NULL;
+ }
+
+ if (test_bit(FSCACHE_IOERROR, &tag->cache->flags))
+ return NULL;
+
+ _leave(" = %p [specific]", tag->cache);
+ return tag->cache;
+
+no_preference:
+ /* netfs has no preference - just select first cache */
+ cache = list_entry(fscache_cache_list.next,
+ struct fscache_cache, link);
+ _leave(" = %p [first]", cache);
+ return cache;
+}
+
+/*****************************************************************************/
+/*
+ * get a backing object for a cookie from the chosen cache
+ * - the cookie must be write-locked by the caller
+ * - all parent indexes will be obtained recursively first
+ */
+static struct fscache_object *fscache_lookup_object(struct fscache_cookie *cookie,
+ struct fscache_cache *cache)
+{
+ struct fscache_cookie *parent = cookie->parent;
+ struct fscache_object *pobject, *object;
+ struct hlist_node *_p;
+
+ _enter("{%s/%s},",
+ parent && parent->def ? parent->def->name : "",
+ cookie->def ? (char *) cookie->def->name : "<file>");
+
+ if (test_bit(FSCACHE_IOERROR, &cache->flags))
+ return NULL;
+
+ /* see if we have the backing object for this cookie + cache immediately
+ * to hand
+ */
+ object = NULL;
+ hlist_for_each_entry(object, _p,
+ &cookie->backing_objects, cookie_link
+ ) {
+ if (object->cache == cache)
+ break;
+ }
+
+ if (object) {
+ _leave(" = %p [old]", object);
+ return object;
+ }
+
+ BUG_ON(!parent); /* FSDEF entries don't have a parent */
+
+ /* we don't have a backing cookie, so we need to consult the object's
+ * parent index in the selected cache and maybe insert an entry
+ * therein; so the first thing to do is make sure that the parent index
+ * is represented on disc
+ */
+ down_read(&parent->sem);
+
+ pobject = NULL;
+ hlist_for_each_entry(pobject, _p,
+ &parent->backing_objects, cookie_link
+ ) {
+ if (pobject->cache == cache)
+ break;
+ }
+
+ if (!pobject) {
+ /* we don't know about the parent object */
+ up_read(&parent->sem);
+ down_write(&parent->sem);
+
+ pobject = fscache_lookup_object(parent, cache);
+ if (IS_ERR(pobject)) {
+ up_write(&parent->sem);
+ _leave(" = %ld [no ipobj]", PTR_ERR(pobject));
+ return pobject;
+ }
+
+ _debug("pobject=%p", pobject);
+
+ BUG_ON(pobject->cookie != parent);
+
+ downgrade_write(&parent->sem);
+ }
+
+ /* now we can attempt to look up this object in the parent, possibly
+ * creating a representation on disc when we do so
+ */
+ object = cache->ops->lookup_object(cache, pobject, cookie);
+ up_read(&parent->sem);
+
+ if (IS_ERR(object)) {
+ _leave(" = %ld [no obj]", PTR_ERR(object));
+ return object;
+ }
+
+ /* keep track of it */
+ cache->ops->lock_object(object);
+
+ BUG_ON(!hlist_unhashed(&object->cookie_link));
+
+ /* 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);
+
+ /* done */
+ cache->ops->unlock_object(object);
+ _leave(" = %p [new]", object);
+ return object;
+}
+
+/*****************************************************************************/
+/*
+ * 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
+ * - idef 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
+ * indexes 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,
+ struct fscache_cookie_def *def,
+ void *netfs_data)
+{
+ struct fscache_cookie *cookie;
+ struct fscache_cache *cache;
+ struct fscache_object *object;
+ int ret = 0;
+
+ BUG_ON(!def);
+
+ _enter("{%s},{%s},%p",
+ parent ? (char *) parent->def->name : "<no-parent>",
+ def->name, netfs_data);
+
+ /* if there's no parent cookie, then we don't create one here either */
+ if (!parent) {
+ _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, SLAB_KERNEL);
+ if (!cookie) {
+ _leave(" [ENOMEM]");
+ return NULL;
+ }
+
+ atomic_set(&cookie->usage, 1);
+ atomic_set(&cookie->children, 0);
+
+ atomic_inc(&parent->usage);
+ atomic_inc(&parent->children);
+
+ cookie->def = def;
+ cookie->parent = parent;
+ cookie->netfs = parent->netfs;
+ cookie->netfs_data = netfs_data;
+
+ /* 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(" = %p [no caches]", cookie);
+ return cookie;
+ }
+
+ /* if the object is an index then we need do nothing more here - we
+ * create indexes on disk when we need them as an index may exist in
+ * multiple caches */
+ if (cookie->def->type != FSCACHE_COOKIE_TYPE_INDEX) {
+ down_write(&cookie->sem);
+
+ /* the object is a file - we need to select a cache in which to
+ * store it */
+ cache = fscache_select_cache_for_object(cookie);
+ if (!cache)
+ goto no_cache; /* couldn't decide on a cache */
+
+ /* create a file index entry on disc, along with all the
+ * indexes required to find it again later */
+ object = fscache_lookup_object(cookie, cache);
+ if (IS_ERR(object)) {
+ ret = PTR_ERR(object);
+ goto error;
+ }
+
+ up_write(&cookie->sem);
+ }
+out:
+ up_read(&fscache_addremove_sem);
+ _leave(" = %p", cookie);
+ return cookie;
+
+no_cache:
+ ret = -ENOMEDIUM;
+ goto error_cleanup;
+error:
+ printk(KERN_ERR "FS-Cache: error from cache: %d\n", ret);
+error_cleanup:
+ if (cookie) {
+ up_write(&cookie->sem);
+ __fscache_cookie_put(cookie);
+ cookie = NULL;
+ atomic_dec(&parent->children);
+ }
+
+ goto out;
+}
+
+EXPORT_SYMBOL(__fscache_acquire_cookie);
+
+/*****************************************************************************/
+/*
+ * release a cookie back to the cache
+ * - the object will be marked as recyclable on disc if retire is true
+ * - all dependents of this cookie must have already been unregistered
+ * (indexes/files/pages)
+ */
+void __fscache_relinquish_cookie(struct fscache_cookie *cookie, int retire)
+{
+ struct fscache_cache *cache;
+ struct fscache_object *object;
+ struct hlist_node *_p;
+
+ if (!cookie) {
+ _leave(" [no cookie]");
+ return;
+ }
+
+ _enter("%p{%s},%d", cookie, cookie->def->name, retire);
+
+ if (atomic_read(&cookie->children) != 0) {
+ printk("FS-Cache: cookie still has children\n");
+ BUG();
+ }
+
+ /* detach pointers back to the netfs */
+ down_write(&cookie->sem);
+
+ cookie->netfs_data = NULL;
+ cookie->def = NULL;
+
+ /* mark retired objects for recycling */
+ if (retire) {
+ hlist_for_each_entry(object, _p,
+ &cookie->backing_objects,
+ cookie_link
+ ) {
+ set_bit(FSCACHE_OBJECT_RECYCLING, &object->flags);
+ }
+ }
+
+ /* 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);
+
+ /* detach each cache object from the object cookie */
+ set_bit(FSCACHE_OBJECT_RELEASING, &object->flags);
+
+ hlist_del_init(&object->cookie_link);
+
+ cache = object->cache;
+ cache->ops->lock_object(object);
+ object->cookie = NULL;
+ cache->ops->unlock_object(object);
+
+ if (atomic_dec_and_test(&cookie->usage))
+ /* the cookie refcount shouldn't be reduced to 0 yet */
+ BUG();
+
+ spin_lock(&cache->object_list_lock);
+ list_del_init(&object->cache_link);
+ spin_unlock(&cache->object_list_lock);
+
+ cache->ops->put_object(object);
+ }
+
+ up_write(&cookie->sem);
+
+ if (cookie->parent) {
+#ifdef CONFIG_DEBUG_SLAB
+ BUG_ON((atomic_read(&cookie->parent->children) & 0xffff0000) == 0x6b6b0000);
+#endif
+ atomic_dec(&cookie->parent->children);
+ }
+
+ /* finally dispose of the cookie */
+ fscache_cookie_put(cookie);
+
+ _leave("");
+}
+
+EXPORT_SYMBOL(__fscache_relinquish_cookie);
+
+/*****************************************************************************/
+/*
+ * update the index entries backing a cookie
+ */
+void __fscache_update_cookie(struct fscache_cookie *cookie)
+{
+ struct fscache_object *object;
+ struct hlist_node *_p;
+
+ if (!cookie) {
+ _leave(" [no cookie]");
+ return;
+ }
+
+ _enter("{%s}", cookie->def->name);
+
+ BUG_ON(!cookie->def->get_aux);
+
+ down_write(&cookie->sem);
+ down_read(&cookie->parent->sem);
+
+ /* update the index entry on disc in each cache backing this cookie */
+ hlist_for_each_entry(object, _p,
+ &cookie->backing_objects, cookie_link
+ ) {
+ if (!test_bit(FSCACHE_IOERROR, &object->cache->flags))
+ object->cache->ops->update_object(object);
+ }
+
+ up_read(&cookie->parent->sem);
+ up_write(&cookie->sem);
+ _leave("");
+}
+
+EXPORT_SYMBOL(__fscache_update_cookie);
+
+/*****************************************************************************/
+/*
+ * destroy a cookie
+ */
+static void __fscache_cookie_put(struct fscache_cookie *cookie)
+{
+ struct fscache_cookie *parent;
+
+ _enter("%p", cookie);
+
+ for (;;) {
+ 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("");
+}
+
+/*****************************************************************************/
+/*
+ * initialise an cookie jar slab element prior to any use
+ */
+void fscache_cookie_init_once(void *_cookie, kmem_cache_t *cachep,
+ unsigned long flags)
+{
+ struct fscache_cookie *cookie = _cookie;
+
+ if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) ==
+ SLAB_CTOR_CONSTRUCTOR) {
+ memset(cookie, 0, sizeof(*cookie));
+ init_rwsem(&cookie->sem);
+ INIT_HLIST_HEAD(&cookie->backing_objects);
+ }
+}
+
+/*****************************************************************************/
+/*
+ * pin an object into the cache
+ */
+int __fscache_pin_cookie(struct fscache_cookie *cookie)
+{
+ struct fscache_object *object;
+ int ret;
+
+ _enter("%p", cookie);
+
+ if (hlist_empty(&cookie->backing_objects)) {
+ _leave(" = -ENOBUFS");
+ return -ENOBUFS;
+ }
+
+ /* not supposed to use this for indexes */
+ BUG_ON(cookie->def->type == FSCACHE_COOKIE_TYPE_INDEX);
+
+ /* prevent the file from being uncached whilst we access it and exclude
+ * read and write attempts on pages
+ */
+ down_write(&cookie->sem);
+
+ ret = -ENOBUFS;
+ if (!hlist_empty(&cookie->backing_objects)) {
+ /* get and pin the backing object */
+ object = hlist_entry(cookie->backing_objects.first,
+ struct fscache_object, cookie_link);
+
+ if (test_bit(FSCACHE_IOERROR, &object->cache->flags))
+ goto out;
+
+ if (!object->cache->ops->pin_object) {
+ ret = -EOPNOTSUPP;
+ goto out;
+ }
+
+ /* prevent the cache from being withdrawn */
+ if (fscache_operation_lock(object)) {
+ if (object->cache->ops->grab_object(object)) {
+ /* ask the cache to honour the operation */
+ ret = object->cache->ops->pin_object(object);
+
+ object->cache->ops->put_object(object);
+ }
+
+ fscache_operation_unlock(object);
+ }
+ }
+
+out:
+ up_write(&cookie->sem);
+ _leave(" = %d", ret);
+ return ret;
+}
+
+EXPORT_SYMBOL(__fscache_pin_cookie);
+
+/*****************************************************************************/
+/*
+ * unpin an object into the cache
+ */
+void __fscache_unpin_cookie(struct fscache_cookie *cookie)
+{
+ struct fscache_object *object;
+ int ret;
+
+ _enter("%p", cookie);
+
+ if (hlist_empty(&cookie->backing_objects)) {
+ _leave(" [no obj]");
+ return;
+ }
+
+ /* not supposed to use this for indexes */
+ BUG_ON(cookie->def->type == FSCACHE_COOKIE_TYPE_INDEX);
+
+ /* prevent the file from being uncached whilst we access it and exclude
+ * read and write attempts on pages
+ */
+ down_write(&cookie->sem);
+
+ ret = -ENOBUFS;
+ if (!hlist_empty(&cookie->backing_objects)) {
+ /* get and unpin the backing object */
+ object = hlist_entry(cookie->backing_objects.first,
+ struct fscache_object, cookie_link);
+
+ if (test_bit(FSCACHE_IOERROR, &object->cache->flags))
+ goto out;
+
+ if (!object->cache->ops->unpin_object)
+ goto out;
+
+ /* prevent the cache from being withdrawn */
+ if (fscache_operation_lock(object)) {
+ if (object->cache->ops->grab_object(object)) {
+ /* ask the cache to honour the operation */
+ object->cache->ops->unpin_object(object);
+
+ object->cache->ops->put_object(object);
+ }
+
+ fscache_operation_unlock(object);
+ }
+ }
+
+out:
+ up_write(&cookie->sem);
+ _leave("");
+}
+
+EXPORT_SYMBOL(__fscache_unpin_cookie);
git://git.onelab.eu / linux-2.6.git / blobdiff