diff options
Diffstat (limited to 'kernel/fs/cachefiles/interface.c')
| -rw-r--r-- | kernel/fs/cachefiles/interface.c | 557 |
1 files changed, 557 insertions, 0 deletions
diff --git a/kernel/fs/cachefiles/interface.c b/kernel/fs/cachefiles/interface.c new file mode 100644 index 000000000..afa023dde --- /dev/null +++ b/kernel/fs/cachefiles/interface.c @@ -0,0 +1,557 @@ +/* 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 "internal.h" + +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), cachefiles_gfp); + if (!lookup_data) + goto nomem_lookup_data; + + /* create a new object record and a temporary leaf image */ + object = kmem_cache_alloc(cachefiles_object_jar, cachefiles_gfp); + 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, cachefiles_gfp); + 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) + pr_warn("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 auxiliary 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); + + if (!fscache_use_cookie(_object)) { + _leave(" [relinq]"); + return; + } + + cookie = object->fscache.cookie; + + if (!cookie->def->get_aux) { + fscache_unuse_cookie(_object); + _leave(" [no aux]"); + return; + } + + auxdata = kmalloc(2 + 512 + 3, cachefiles_gfp); + if (!auxdata) { + fscache_unuse_cookie(_object); + _leave(" [nomem]"); + return; + } + + auxlen = cookie->def->get_aux(cookie->netfs_data, auxdata->data, 511); + fscache_unuse_cookie(_object); + 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 + + /* We need to tidy the object up if we did in fact manage to open it. + * It's possible for us to get here before the object is fully + * initialised if the parent goes away or the object gets retired + * before we set it up. + */ + if (object->dentry) { + /* delete retired objects */ + if (test_bit(FSCACHE_OBJECT_RETIRED, &object->fscache.flags) && + _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); +} + +/* + * check if the backing cache is updated to FS-Cache + * - called by FS-Cache when evaluates if need to invalidate the cache + */ +static bool cachefiles_check_consistency(struct fscache_operation *op) +{ + struct cachefiles_object *object; + struct cachefiles_cache *cache; + const struct cred *saved_cred; + int ret; + + _enter("{OBJ%x}", op->object->debug_id); + + object = container_of(op->object, struct cachefiles_object, fscache); + cache = container_of(object->fscache.cache, + struct cachefiles_cache, cache); + + cachefiles_begin_secure(cache, &saved_cred); + ret = cachefiles_check_auxdata(object); + cachefiles_end_secure(cache, saved_cred); + + _leave(" = %d", ret); + return 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(d_is_reg(object->backer)); + + fscache_set_store_limit(&object->fscache, ni_size); + + oi_size = i_size_read(d_backing_inode(object->backer)); + if (oi_size == ni_size) + return 0; + + cachefiles_begin_secure(cache, &saved_cred); + mutex_lock(&d_inode(object->backer)->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, NULL); + if (ret < 0) + goto truncate_failed; + } + + newattrs.ia_valid = ATTR_SIZE; + newattrs.ia_size = ni_size; + ret = notify_change(object->backer, &newattrs, NULL); + +truncate_failed: + mutex_unlock(&d_inode(object->backer)->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; +} + +/* + * Invalidate an object + */ +static void cachefiles_invalidate_object(struct fscache_operation *op) +{ + struct cachefiles_object *object; + struct cachefiles_cache *cache; + const struct cred *saved_cred; + struct path path; + uint64_t ni_size; + int ret; + + object = container_of(op->object, struct cachefiles_object, fscache); + cache = container_of(object->fscache.cache, + struct cachefiles_cache, cache); + + op->object->cookie->def->get_attr(op->object->cookie->netfs_data, + &ni_size); + + _enter("{OBJ%x},[%llu]", + op->object->debug_id, (unsigned long long)ni_size); + + if (object->backer) { + ASSERT(d_is_reg(object->backer)); + + fscache_set_store_limit(&object->fscache, ni_size); + + path.dentry = object->backer; + path.mnt = cache->mnt; + + cachefiles_begin_secure(cache, &saved_cred); + ret = vfs_truncate(&path, 0); + if (ret == 0) + ret = vfs_truncate(&path, ni_size); + cachefiles_end_secure(cache, saved_cred); + + if (ret != 0) { + fscache_set_store_limit(&object->fscache, 0); + if (ret == -EIO) + cachefiles_io_error_obj(object, + "Invalidate failed"); + } + } + + fscache_op_complete(op, true); + _leave(""); +} + +/* + * 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, + .invalidate_object = cachefiles_invalidate_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, + .check_consistency = cachefiles_check_consistency, +}; 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