/* 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_DIRECT_RECLAIM); 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_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_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); 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->def->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, 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, 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); 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);