/* FS-Cache interface to CacheFiles * * Copyright (C) 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 Licence * as published by the Free Software Foundation; either version * 2 of the Licence, or (at your option) any later version. */ #include <linux/slab.h> #include <linux/mount.h> #include <linux/buffer_head.h> #include "internal.h" #define list_to_page(head) (list_entry((head)->prev, struct page, lru)) struct cachefiles_lookup_data { struct cachefiles_xattr *auxdata; /* auxiliary data */ char *key; /* key path */ }; static int cachefiles_attr_changed(struct fscache_object *_object); /* * allocate an object record for a cookie lookup and prepare the lookup data */ static struct fscache_object *cachefiles_alloc_object( struct fscache_cache *_cache, struct fscache_cookie *cookie) { struct cachefiles_lookup_data *lookup_data; struct cachefiles_object *object; struct cachefiles_cache *cache; struct cachefiles_xattr *auxdata; unsigned keylen, auxlen; void *buffer; char *key; cache = container_of(_cache, struct cachefiles_cache, cache); _enter("{%s},%p,", cache->cache.identifier, cookie); lookup_data = kmalloc(sizeof(*lookup_data), GFP_KERNEL); if (!lookup_data) goto nomem_lookup_data; /* create a new object record and a temporary leaf image */ object = kmem_cache_alloc(cachefiles_object_jar, GFP_KERNEL); if (!object) goto nomem_object; ASSERTCMP(object->backer, ==, NULL); BUG_ON(test_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags)); atomic_set(&object->usage, 1); fscache_object_init(&object->fscache, cookie, &cache->cache); object->type = cookie->def->type; /* get hold of the raw key * - stick the length on the front and leave space on the back for the * encoder */ buffer = kmalloc((2 + 512) + 3, GFP_KERNEL); if (!buffer) goto nomem_buffer; keylen = cookie->def->get_key(cookie->netfs_data, buffer + 2, 512); ASSERTCMP(keylen, <, 512); *(uint16_t *)buffer = keylen; ((char *)buffer)[keylen + 2] = 0; ((char *)buffer)[keylen + 3] = 0; ((char *)buffer)[keylen + 4] = 0; /* turn the raw key into something that can work with as a filename */ key = cachefiles_cook_key(buffer, keylen + 2, object->type); if (!key) goto nomem_key; /* get hold of the auxiliary data and prepend the object type */ auxdata = buffer; auxlen = 0; if (cookie->def->get_aux) { auxlen = cookie->def->get_aux(cookie->netfs_data, auxdata->data, 511); ASSERTCMP(auxlen, <, 511); } auxdata->len = auxlen + 1; auxdata->type = cookie->def->type; lookup_data->auxdata = auxdata; lookup_data->key = key; object->lookup_data = lookup_data; _leave(" = %p [%p]", &object->fscache, lookup_data); return &object->fscache; nomem_key: kfree(buffer); nomem_buffer: BUG_ON(test_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags)); kmem_cache_free(cachefiles_object_jar, object); fscache_object_destroyed(&cache->cache); nomem_object: kfree(lookup_data); nomem_lookup_data: _leave(" = -ENOMEM"); return ERR_PTR(-ENOMEM); } /* * attempt to look up the nominated node in this cache * - return -ETIMEDOUT to be scheduled again */ static int cachefiles_lookup_object(struct fscache_object *_object) { struct cachefiles_lookup_data *lookup_data; struct cachefiles_object *parent, *object; struct cachefiles_cache *cache; const struct cred *saved_cred; int ret; _enter("{OBJ%x}", _object->debug_id); cache = container_of(_object->cache, struct cachefiles_cache, cache); parent = container_of(_object->parent, struct cachefiles_object, fscache); object = container_of(_object, struct cachefiles_object, fscache); lookup_data = object->lookup_data; ASSERTCMP(lookup_data, !=, NULL); /* look up the key, creating any missing bits */ cachefiles_begin_secure(cache, &saved_cred); ret = cachefiles_walk_to_object(parent, object, lookup_data->key, lookup_data->auxdata); cachefiles_end_secure(cache, saved_cred); /* polish off by setting the attributes of non-index files */ if (ret == 0 && object->fscache.cookie->def->type != FSCACHE_COOKIE_TYPE_INDEX) cachefiles_attr_changed(&object->fscache); if (ret < 0 && ret != -ETIMEDOUT) { if (ret != -ENOBUFS) printk(KERN_WARNING "CacheFiles: Lookup failed error %d\n", ret); fscache_object_lookup_error(&object->fscache); } _leave(" [%d]", ret); return ret; } /* * indication of lookup completion */ static void cachefiles_lookup_complete(struct fscache_object *_object) { struct cachefiles_object *object; object = container_of(_object, struct cachefiles_object, fscache); _enter("{OBJ%x,%p}", object->fscache.debug_id, object->lookup_data); if (object->lookup_data) { kfree(object->lookup_data->key); kfree(object->lookup_data->auxdata); kfree(object->lookup_data); object->lookup_data = NULL; } } /* * increment the usage count on an inode object (may fail if unmounting) */ static struct fscache_object *cachefiles_grab_object(struct fscache_object *_object) { struct cachefiles_object *object = container_of(_object, struct cachefiles_object, fscache); _enter("{OBJ%x,%d}", _object->debug_id, atomic_read(&object->usage)); #ifdef CACHEFILES_DEBUG_SLAB ASSERT((atomic_read(&object->usage) & 0xffff0000) != 0x6b6b0000); #endif atomic_inc(&object->usage); return &object->fscache; } /* * update the auxilliary data for an object object on disk */ static void cachefiles_update_object(struct fscache_object *_object) { struct cachefiles_object *object; struct cachefiles_xattr *auxdata; struct cachefiles_cache *cache; struct fscache_cookie *cookie; const struct cred *saved_cred; unsigned auxlen; _enter("{OBJ%x}", _object->debug_id); object = container_of(_object, struct cachefiles_object, fscache); cache = container_of(object->fscache.cache, struct cachefiles_cache, cache); cookie = object->fscache.cookie; if (!cookie->def->get_aux) { _leave(" [no aux]"); return; } auxdata = kmalloc(2 + 512 + 3, GFP_KERNEL); if (!auxdata) { _leave(" [nomem]"); return; } auxlen = cookie->def->get_aux(cookie->netfs_data, auxdata->data, 511); ASSERTCMP(auxlen, <, 511); auxdata->len = auxlen + 1; auxdata->type = cookie->def->type; cachefiles_begin_secure(cache, &saved_cred); cachefiles_update_object_xattr(object, auxdata); cachefiles_end_secure(cache, saved_cred); kfree(auxdata); _leave(""); } /* * discard the resources pinned by an object and effect retirement if * requested */ static void cachefiles_drop_object(struct fscache_object *_object) { struct cachefiles_object *object; struct cachefiles_cache *cache; const struct cred *saved_cred; ASSERT(_object); object = container_of(_object, struct cachefiles_object, fscache); _enter("{OBJ%x,%d}", object->fscache.debug_id, atomic_read(&object->usage)); cache = container_of(object->fscache.cache, struct cachefiles_cache, cache); #ifdef CACHEFILES_DEBUG_SLAB ASSERT((atomic_read(&object->usage) & 0xffff0000) != 0x6b6b0000); #endif /* delete retired objects */ if (object->fscache.state == FSCACHE_OBJECT_RECYCLING && _object != cache->cache.fsdef ) { _debug("- retire object OBJ%x", object->fscache.debug_id); cachefiles_begin_secure(cache, &saved_cred); cachefiles_delete_object(cache, object); cachefiles_end_secure(cache, saved_cred); } /* close the filesystem stuff attached to the object */ if (object->backer != object->dentry) dput(object->backer); object->backer = NULL; /* note that the object is now inactive */ if (test_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags)) { write_lock(&cache->active_lock); if (!test_and_clear_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags)) BUG(); rb_erase(&object->active_node, &cache->active_nodes); wake_up_bit(&object->flags, CACHEFILES_OBJECT_ACTIVE); write_unlock(&cache->active_lock); } dput(object->dentry); object->dentry = NULL; _leave(""); } /* * dispose of a reference to an object */ static void cachefiles_put_object(struct fscache_object *_object) { struct cachefiles_object *object; struct fscache_cache *cache; ASSERT(_object); object = container_of(_object, struct cachefiles_object, fscache); _enter("{OBJ%x,%d}", object->fscache.debug_id, atomic_read(&object->usage)); #ifdef CACHEFILES_DEBUG_SLAB ASSERT((atomic_read(&object->usage) & 0xffff0000) != 0x6b6b0000); #endif ASSERTIFCMP(object->fscache.parent, object->fscache.parent->n_children, >, 0); if (atomic_dec_and_test(&object->usage)) { _debug("- kill object OBJ%x", object->fscache.debug_id); ASSERT(!test_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags)); ASSERTCMP(object->fscache.parent, ==, NULL); ASSERTCMP(object->backer, ==, NULL); ASSERTCMP(object->dentry, ==, NULL); ASSERTCMP(object->fscache.n_ops, ==, 0); ASSERTCMP(object->fscache.n_children, ==, 0); if (object->lookup_data) { kfree(object->lookup_data->key); kfree(object->lookup_data->auxdata); kfree(object->lookup_data); object->lookup_data = NULL; } cache = object->fscache.cache; fscache_object_destroy(&object->fscache); kmem_cache_free(cachefiles_object_jar, object); fscache_object_destroyed(cache); } _leave(""); } /* * sync a cache */ static void cachefiles_sync_cache(struct fscache_cache *_cache) { struct cachefiles_cache *cache; const struct cred *saved_cred; int ret; _enter("%p", _cache); cache = container_of(_cache, struct cachefiles_cache, cache); /* make sure all pages pinned by operations on behalf of the netfs are * written to disc */ cachefiles_begin_secure(cache, &saved_cred); down_read(&cache->mnt->mnt_sb->s_umount); ret = sync_filesystem(cache->mnt->mnt_sb); up_read(&cache->mnt->mnt_sb->s_umount); cachefiles_end_secure(cache, saved_cred); if (ret == -EIO) cachefiles_io_error(cache, "Attempt to sync backing fs superblock" " returned error %d", ret); } /* * notification the attributes on an object have changed * - called with reads/writes excluded by FS-Cache */ static int cachefiles_attr_changed(struct fscache_object *_object) { struct cachefiles_object *object; struct cachefiles_cache *cache; const struct cred *saved_cred; struct iattr newattrs; uint64_t ni_size; loff_t oi_size; int ret; _object->cookie->def->get_attr(_object->cookie->netfs_data, &ni_size); _enter("{OBJ%x},[%llu]", _object->debug_id, (unsigned long long) ni_size); object = container_of(_object, struct cachefiles_object, fscache); cache = container_of(object->fscache.cache, struct cachefiles_cache, cache); if (ni_size == object->i_size) return 0; if (!object->backer) return -ENOBUFS; ASSERT(S_ISREG(object->backer->d_inode->i_mode)); fscache_set_store_limit(&object->fscache, ni_size); oi_size = i_size_read(object->backer->d_inode); if (oi_size == ni_size) return 0; cachefiles_begin_secure(cache, &saved_cred); mutex_lock(&object->backer->d_inode->i_mutex); /* if there's an extension to a partial page at the end of the backing * file, we need to discard the partial page so that we pick up new * data after it */ if (oi_size & ~PAGE_MASK && ni_size > oi_size) { _debug("discard tail %llx", oi_size); newattrs.ia_valid = ATTR_SIZE; newattrs.ia_size = oi_size & PAGE_MASK; ret = notify_change(object->backer, &newattrs); if (ret < 0) goto truncate_failed; } newattrs.ia_valid = ATTR_SIZE; newattrs.ia_size = ni_size; ret = notify_change(object->backer, &newattrs); truncate_failed: mutex_unlock(&object->backer->d_inode->i_mutex); cachefiles_end_secure(cache, saved_cred); if (ret == -EIO) { fscache_set_store_limit(&object->fscache, 0); cachefiles_io_error_obj(object, "Size set failed"); ret = -ENOBUFS; } _leave(" = %d", ret); return ret; } /* * dissociate a cache from all the pages it was backing */ static void cachefiles_dissociate_pages(struct fscache_cache *cache) { _enter(""); } const struct fscache_cache_ops cachefiles_cache_ops = { .name = "cachefiles", .alloc_object = cachefiles_alloc_object, .lookup_object = cachefiles_lookup_object, .lookup_complete = cachefiles_lookup_complete, .grab_object = cachefiles_grab_object, .update_object = cachefiles_update_object, .drop_object = cachefiles_drop_object, .put_object = cachefiles_put_object, .sync_cache = cachefiles_sync_cache, .attr_changed = cachefiles_attr_changed, .read_or_alloc_page = cachefiles_read_or_alloc_page, .read_or_alloc_pages = cachefiles_read_or_alloc_pages, .allocate_page = cachefiles_allocate_page, .allocate_pages = cachefiles_allocate_pages, .write_page = cachefiles_write_page, .uncache_page = cachefiles_uncache_page, .dissociate_pages = cachefiles_dissociate_pages, };