diff options
Diffstat (limited to 'fs/fscache/cookie.c')
| -rw-r--r-- | fs/fscache/cookie.c | 722 |
1 files changed, 722 insertions, 0 deletions
diff --git a/fs/fscache/cookie.c b/fs/fscache/cookie.c new file mode 100644 index 000000000..89acec742 --- /dev/null +++ b/fs/fscache/cookie.c @@ -0,0 +1,722 @@ +/* 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, + 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, + 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, + 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) { + pr_err("Cookie '%s' still has children\n", + cookie->def->name); + BUG(); + } + + wait_on_bit_lock(&cookie->flags, FSCACHE_COOKIE_ENABLEMENT_LOCK, + 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); |