1 files changed, 310 insertions, 437 deletions

diff --git a/fs/cachefiles/interface.c b/fs/cachefiles/interface.c
index da28ac1fa225..51c968cd00a6 100644
--- a/fs/cachefiles/interface.c
+++ b/fs/cachefiles/interface.c
@@ -1,572 +1,445 @@
 // SPDX-License-Identifier: GPL-2.0-or-later
 /* FS-Cache interface to CacheFiles
  *
- * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
+ * Copyright (C) 2021 Red Hat, Inc. All Rights Reserved.
  * Written by David Howells (dhowells@redhat.com)
  */
 
 #include <linux/slab.h>
 #include <linux/mount.h>
+#include <linux/xattr.h>
+#include <linux/file.h>
+#include <linux/falloc.h>
+#include <trace/events/fscache.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);
+static atomic_t cachefiles_object_debug_id;
 
 /*
- * allocate an object record for a cookie lookup and prepare the lookup data
+ * Allocate a cache object record.
  */
-static struct fscache_object *cachefiles_alloc_object(
-	struct fscache_cache *_cache,
-	struct fscache_cookie *cookie)
+static
+struct cachefiles_object *cachefiles_alloc_object(struct fscache_cookie *cookie)
 {
-	struct cachefiles_lookup_data *lookup_data;
+	struct fscache_volume *vcookie = cookie->volume;
+	struct cachefiles_volume *volume = vcookie->cache_priv;
 	struct cachefiles_object *object;
-	struct cachefiles_cache *cache;
-	struct cachefiles_xattr *auxdata;
-	unsigned keylen, auxlen;
-	void *buffer, *p;
-	char *key;
 
-	cache = container_of(_cache, struct cachefiles_cache, cache);
+	_enter("{%s},%x,", vcookie->key, cookie->debug_id);
 
-	_enter("{%s},%x,", cache->cache.identifier, cookie->debug_id);
-
-	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);
+	object = kmem_cache_zalloc(cachefiles_object_jar, GFP_KERNEL);
 	if (!object)
-		goto nomem_object;
-
-	ASSERTCMP(object->backer, ==, NULL);
+		return NULL;
 
-	BUG_ON(test_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags));
-	atomic_set(&object->usage, 1);
+	refcount_set(&object->ref, 1);
 
-	fscache_object_init(&object->fscache, cookie, &cache->cache);
+	spin_lock_init(&object->lock);
+	INIT_LIST_HEAD(&object->cache_link);
+	object->volume = volume;
+	object->debug_id = atomic_inc_return(&cachefiles_object_debug_id);
+	object->cookie = fscache_get_cookie(cookie, fscache_cookie_get_attach_object);
 
-	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->key_len;
-	if (keylen <= sizeof(cookie->inline_key))
-		p = cookie->inline_key;
-	else
-		p = cookie->key;
-	memcpy(buffer + 2, p, keylen);
-
-	*(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 = cookie->aux_len;
-	if (auxlen) {
-		if (auxlen <= sizeof(cookie->inline_aux))
-			p = cookie->inline_aux;
-		else
-			p = cookie->aux;
-		memcpy(auxdata->data, p, auxlen);
-	}
-
-	auxdata->len = auxlen + 1;
-	auxdata->type = cookie->type;
-
-	lookup_data->auxdata = auxdata;
-	lookup_data->key = key;
-	object->lookup_data = lookup_data;
-
-	_leave(" = %x [%p]", object->fscache.debug_id, 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);
+	fscache_count_object(vcookie->cache);
+	trace_cachefiles_ref(object->debug_id, cookie->debug_id, 1,
+			     cachefiles_obj_new);
+	return object;
 }
 
 /*
- * attempt to look up the nominated node in this cache
- * - return -ETIMEDOUT to be scheduled again
+ * Note that an object has been seen.
  */
-static int cachefiles_lookup_object(struct fscache_object *_object)
+void cachefiles_see_object(struct cachefiles_object *object,
+			   enum cachefiles_obj_ref_trace why)
 {
-	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;
+	trace_cachefiles_ref(object->debug_id, object->cookie->debug_id,
+			     refcount_read(&object->ref), why);
 }
 
 /*
- * indication of lookup completion
+ * Increment the usage count on an object;
  */
-static void cachefiles_lookup_complete(struct fscache_object *_object)
+struct cachefiles_object *cachefiles_grab_object(struct cachefiles_object *object,
+						 enum cachefiles_obj_ref_trace why)
 {
-	struct cachefiles_object *object;
-
-	object = container_of(_object, struct cachefiles_object, fscache);
-
-	_enter("{OBJ%x,%p}", object->fscache.debug_id, object->lookup_data);
+	int r;
 
-	if (object->lookup_data) {
-		kfree(object->lookup_data->key);
-		kfree(object->lookup_data->auxdata);
-		kfree(object->lookup_data);
-		object->lookup_data = NULL;
-	}
+	__refcount_inc(&object->ref, &r);
+	trace_cachefiles_ref(object->debug_id, object->cookie->debug_id, r, why);
+	return object;
 }
 
 /*
- * increment the usage count on an inode object (may fail if unmounting)
+ * dispose of a reference to an object
  */
-static
-struct fscache_object *cachefiles_grab_object(struct fscache_object *_object,
-					      enum fscache_obj_ref_trace why)
+void cachefiles_put_object(struct cachefiles_object *object,
+			   enum cachefiles_obj_ref_trace why)
 {
-	struct cachefiles_object *object =
-		container_of(_object, struct cachefiles_object, fscache);
-	int u;
+	unsigned int object_debug_id = object->debug_id;
+	unsigned int cookie_debug_id = object->cookie->debug_id;
+	struct fscache_cache *cache;
+	bool done;
+	int r;
+
+	done = __refcount_dec_and_test(&object->ref, &r);
+	trace_cachefiles_ref(object_debug_id, cookie_debug_id, r, why);
+	if (done) {
+		_debug("- kill object OBJ%x", object_debug_id);
+
+		ASSERTCMP(object->file, ==, NULL);
 
-	_enter("{OBJ%x,%d}", _object->debug_id, atomic_read(&object->usage));
+		kfree(object->d_name);
 
-#ifdef CACHEFILES_DEBUG_SLAB
-	ASSERT((atomic_read(&object->usage) & 0xffff0000) != 0x6b6b0000);
-#endif
+		cache = object->volume->cache->cache;
+		fscache_put_cookie(object->cookie, fscache_cookie_put_object);
+		object->cookie = NULL;
+		kmem_cache_free(cachefiles_object_jar, object);
+		fscache_uncount_object(cache);
+	}
 
-	u = atomic_inc_return(&object->usage);
-	trace_cachefiles_ref(object, _object->cookie,
-			     (enum cachefiles_obj_ref_trace)why, u);
-	return &object->fscache;
+	_leave("");
 }
 
 /*
- * update the auxiliary data for an object object on disk
+ * Adjust the size of a cache file if necessary to match the DIO size.  We keep
+ * the EOF marker a multiple of DIO blocks so that we don't fall back to doing
+ * non-DIO for a partial block straddling the EOF, but we also have to be
+ * careful of someone expanding the file and accidentally accreting the
+ * padding.
  */
-static void cachefiles_update_object(struct fscache_object *_object)
+static int cachefiles_adjust_size(struct cachefiles_object *object)
 {
-	struct cachefiles_object *object;
-	struct cachefiles_xattr *auxdata;
-	struct cachefiles_cache *cache;
-	struct fscache_cookie *cookie;
-	const struct cred *saved_cred;
-	const void *aux;
-	unsigned auxlen;
+	struct iattr newattrs;
+	struct file *file = object->file;
+	uint64_t ni_size;
+	loff_t oi_size;
+	int ret;
 
-	_enter("{OBJ%x}", _object->debug_id);
+	ni_size = object->cookie->object_size;
+	ni_size = round_up(ni_size, CACHEFILES_DIO_BLOCK_SIZE);
 
-	object = container_of(_object, struct cachefiles_object, fscache);
-	cache = container_of(object->fscache.cache, struct cachefiles_cache,
-			     cache);
+	_enter("{OBJ%x},[%llu]",
+	       object->debug_id, (unsigned long long) ni_size);
 
-	if (!fscache_use_cookie(_object)) {
-		_leave(" [relinq]");
-		return;
-	}
+	if (!file)
+		return -ENOBUFS;
 
-	cookie = object->fscache.cookie;
-	auxlen = cookie->aux_len;
+	oi_size = i_size_read(file_inode(file));
+	if (oi_size == ni_size)
+		return 0;
 
-	if (!auxlen) {
-		fscache_unuse_cookie(_object);
-		_leave(" [no aux]");
-		return;
-	}
+	inode_lock(file_inode(file));
 
-	auxdata = kmalloc(2 + auxlen + 3, cachefiles_gfp);
-	if (!auxdata) {
-		fscache_unuse_cookie(_object);
-		_leave(" [nomem]");
-		return;
+	/* 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 = cachefiles_inject_remove_error();
+		if (ret == 0)
+			ret = notify_change(&init_user_ns, file->f_path.dentry,
+					    &newattrs, NULL);
+		if (ret < 0)
+			goto truncate_failed;
 	}
 
-	aux = (auxlen <= sizeof(cookie->inline_aux)) ?
-		cookie->inline_aux : cookie->aux;
+	newattrs.ia_valid = ATTR_SIZE;
+	newattrs.ia_size = ni_size;
+	ret = cachefiles_inject_write_error();
+	if (ret == 0)
+		ret = notify_change(&init_user_ns, file->f_path.dentry,
+				    &newattrs, NULL);
 
-	memcpy(auxdata->data, aux, auxlen);
-	fscache_unuse_cookie(_object);
+truncate_failed:
+	inode_unlock(file_inode(file));
 
-	auxdata->len = auxlen + 1;
-	auxdata->type = cookie->type;
+	if (ret < 0)
+		trace_cachefiles_io_error(NULL, file_inode(file), ret,
+					  cachefiles_trace_notify_change_error);
+	if (ret == -EIO) {
+		cachefiles_io_error_obj(object, "Size set failed");
+		ret = -ENOBUFS;
+	}
 
-	cachefiles_begin_secure(cache, &saved_cred);
-	cachefiles_update_object_xattr(object, auxdata);
-	cachefiles_end_secure(cache, saved_cred);
-	kfree(auxdata);
-	_leave("");
+	_leave(" = %d", ret);
+	return ret;
 }
 
 /*
- * discard the resources pinned by an object and effect retirement if
- * requested
+ * Attempt to look up the nominated node in this cache
  */
-static void cachefiles_drop_object(struct fscache_object *_object)
+static bool cachefiles_lookup_cookie(struct fscache_cookie *cookie)
 {
 	struct cachefiles_object *object;
-	struct cachefiles_cache *cache;
+	struct cachefiles_cache *cache = cookie->volume->cache->cache_priv;
 	const struct cred *saved_cred;
-	struct inode *inode;
-	blkcnt_t i_blocks = 0;
+	bool success;
 
-	ASSERT(_object);
+	object = cachefiles_alloc_object(cookie);
+	if (!object)
+		goto fail;
 
-	object = container_of(_object, struct cachefiles_object, fscache);
+	_enter("{OBJ%x}", object->debug_id);
 
-	_enter("{OBJ%x,%d}",
-	       object->fscache.debug_id, atomic_read(&object->usage));
+	if (!cachefiles_cook_key(object))
+		goto fail_put;
 
-	cache = container_of(object->fscache.cache,
-			     struct cachefiles_cache, cache);
+	cookie->cache_priv = object;
 
-#ifdef CACHEFILES_DEBUG_SLAB
-	ASSERT((atomic_read(&object->usage) & 0xffff0000) != 0x6b6b0000);
-#endif
+	cachefiles_begin_secure(cache, &saved_cred);
 
-	/* 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);
-			inode = d_backing_inode(object->dentry);
-			if (inode)
-				i_blocks = inode->i_blocks;
-
-			cachefiles_begin_secure(cache, &saved_cred);
-			cachefiles_delete_object(cache, object);
-			cachefiles_end_secure(cache, saved_cred);
-		}
+	success = cachefiles_look_up_object(object);
+	if (!success)
+		goto fail_withdraw;
 
-		/* close the filesystem stuff attached to the object */
-		if (object->backer != object->dentry)
-			dput(object->backer);
-		object->backer = NULL;
-	}
+	cachefiles_see_object(object, cachefiles_obj_see_lookup_cookie);
+
+	spin_lock(&cache->object_list_lock);
+	list_add(&object->cache_link, &cache->object_list);
+	spin_unlock(&cache->object_list_lock);
+	cachefiles_adjust_size(object);
 
-	/* note that the object is now inactive */
-	if (test_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags))
-		cachefiles_mark_object_inactive(cache, object, i_blocks);
+	cachefiles_end_secure(cache, saved_cred);
+	_leave(" = t");
+	return true;
 
-	dput(object->dentry);
-	object->dentry = NULL;
+fail_withdraw:
+	cachefiles_end_secure(cache, saved_cred);
+	cachefiles_see_object(object, cachefiles_obj_see_lookup_failed);
+	fscache_caching_failed(cookie);
+	_debug("failed c=%08x o=%08x", cookie->debug_id, object->debug_id);
+	/* The caller holds an access count on the cookie, so we need them to
+	 * drop it before we can withdraw the object.
+	 */
+	return false;
 
-	_leave("");
+fail_put:
+	cachefiles_put_object(object, cachefiles_obj_put_alloc_fail);
+fail:
+	return false;
 }
 
 /*
- * dispose of a reference to an object
+ * Shorten the backing object to discard any dirty data and free up
+ * any unused granules.
  */
-void cachefiles_put_object(struct fscache_object *_object,
-			   enum fscache_obj_ref_trace why)
+static bool cachefiles_shorten_object(struct cachefiles_object *object,
+				      struct file *file, loff_t new_size)
 {
-	struct cachefiles_object *object;
-	struct fscache_cache *cache;
-	int u;
-
-	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);
-
-	u = atomic_dec_return(&object->usage);
-	trace_cachefiles_ref(object, _object->cookie,
-			     (enum cachefiles_obj_ref_trace)why, u);
-	ASSERTCMP(u, !=, -1);
-	if (u == 0) {
-		_debug("- kill object OBJ%x", object->fscache.debug_id);
+	struct cachefiles_cache *cache = object->volume->cache;
+	struct inode *inode = file_inode(file);
+	loff_t i_size, dio_size;
+	int ret;
 
-		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);
+	dio_size = round_up(new_size, CACHEFILES_DIO_BLOCK_SIZE);
+	i_size = i_size_read(inode);
+
+	trace_cachefiles_trunc(object, inode, i_size, dio_size,
+			       cachefiles_trunc_shrink);
+	ret = cachefiles_inject_remove_error();
+	if (ret == 0)
+		ret = vfs_truncate(&file->f_path, dio_size);
+	if (ret < 0) {
+		trace_cachefiles_io_error(object, file_inode(file), ret,
+					  cachefiles_trace_trunc_error);
+		cachefiles_io_error_obj(object, "Trunc-to-size failed %d", ret);
+		cachefiles_remove_object_xattr(cache, object, file->f_path.dentry);
+		return false;
+	}
 
-		if (object->lookup_data) {
-			kfree(object->lookup_data->key);
-			kfree(object->lookup_data->auxdata);
-			kfree(object->lookup_data);
-			object->lookup_data = NULL;
+	if (new_size < dio_size) {
+		trace_cachefiles_trunc(object, inode, dio_size, new_size,
+				       cachefiles_trunc_dio_adjust);
+		ret = cachefiles_inject_write_error();
+		if (ret == 0)
+			ret = vfs_fallocate(file, FALLOC_FL_ZERO_RANGE,
+					    new_size, dio_size);
+		if (ret < 0) {
+			trace_cachefiles_io_error(object, file_inode(file), ret,
+						  cachefiles_trace_fallocate_error);
+			cachefiles_io_error_obj(object, "Trunc-to-dio-size failed %d", ret);
+			cachefiles_remove_object_xattr(cache, object, file->f_path.dentry);
+			return false;
 		}
-
-		cache = object->fscache.cache;
-		fscache_object_destroy(&object->fscache);
-		kmem_cache_free(cachefiles_object_jar, object);
-		fscache_object_destroyed(cache);
 	}
 
-	_leave("");
+	return true;
 }
 
 /*
- * sync a cache
+ * Resize the backing object.
  */
-static void cachefiles_sync_cache(struct fscache_cache *_cache)
+static void cachefiles_resize_cookie(struct netfs_cache_resources *cres,
+				     loff_t new_size)
 {
-	struct cachefiles_cache *cache;
+	struct cachefiles_object *object = cachefiles_cres_object(cres);
+	struct cachefiles_cache *cache = object->volume->cache;
+	struct fscache_cookie *cookie = object->cookie;
 	const struct cred *saved_cred;
-	int ret;
+	struct file *file = cachefiles_cres_file(cres);
+	loff_t old_size = cookie->object_size;
 
-	_enter("%s", _cache->tag->name);
+	_enter("%llu->%llu", old_size, new_size);
 
-	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 (new_size < old_size) {
+		cachefiles_begin_secure(cache, &saved_cred);
+		cachefiles_shorten_object(object, file, new_size);
+		cachefiles_end_secure(cache, saved_cred);
+		object->cookie->object_size = new_size;
+		return;
+	}
 
-	if (ret == -EIO)
-		cachefiles_io_error(cache,
-				    "Attempt to sync backing fs superblock"
-				    " returned error %d",
-				    ret);
+	/* The file is being expanded.  We don't need to do anything
+	 * particularly.  cookie->initial_size doesn't change and so the point
+	 * at which we have to download before doesn't change.
+	 */
+	cookie->object_size = new_size;
 }
 
 /*
- * check if the backing cache is updated to FS-Cache
- * - called by FS-Cache when evaluates if need to invalidate the cache
+ * Commit changes to the object as we drop it.
  */
-static int cachefiles_check_consistency(struct fscache_operation *op)
+static void cachefiles_commit_object(struct cachefiles_object *object,
+				     struct cachefiles_cache *cache)
 {
-	struct cachefiles_object *object;
-	struct cachefiles_cache *cache;
-	const struct cred *saved_cred;
-	int ret;
+	bool update = false;
 
-	_enter("{OBJ%x}", op->object->debug_id);
+	if (test_and_clear_bit(FSCACHE_COOKIE_LOCAL_WRITE, &object->cookie->flags))
+		update = true;
+	if (test_and_clear_bit(FSCACHE_COOKIE_NEEDS_UPDATE, &object->cookie->flags))
+		update = true;
+	if (update)
+		cachefiles_set_object_xattr(object);
 
-	object = container_of(op->object, struct cachefiles_object, fscache);
-	cache = container_of(object->fscache.cache,
-			     struct cachefiles_cache, cache);
+	if (test_bit(CACHEFILES_OBJECT_USING_TMPFILE, &object->flags))
+		cachefiles_commit_tmpfile(cache, object);
+}
 
-	cachefiles_begin_secure(cache, &saved_cred);
-	ret = cachefiles_check_auxdata(object);
-	cachefiles_end_secure(cache, saved_cred);
+/*
+ * Finalise and object and close the VFS structs that we have.
+ */
+static void cachefiles_clean_up_object(struct cachefiles_object *object,
+				       struct cachefiles_cache *cache)
+{
+	if (test_bit(FSCACHE_COOKIE_RETIRED, &object->cookie->flags)) {
+		if (!test_bit(CACHEFILES_OBJECT_USING_TMPFILE, &object->flags)) {
+			cachefiles_see_object(object, cachefiles_obj_see_clean_delete);
+			_debug("- inval object OBJ%x", object->debug_id);
+			cachefiles_delete_object(object, FSCACHE_OBJECT_WAS_RETIRED);
+		} else {
+			cachefiles_see_object(object, cachefiles_obj_see_clean_drop_tmp);
+			_debug("- inval object OBJ%x tmpfile", object->debug_id);
+		}
+	} else {
+		cachefiles_see_object(object, cachefiles_obj_see_clean_commit);
+		cachefiles_commit_object(object, cache);
+	}
 
-	_leave(" = %d", ret);
-	return ret;
+	cachefiles_unmark_inode_in_use(object, object->file);
+	if (object->file) {
+		fput(object->file);
+		object->file = NULL;
+	}
 }
 
 /*
- * notification the attributes on an object have changed
- * - called with reads/writes excluded by FS-Cache
+ * Withdraw caching for a cookie.
  */
-static int cachefiles_attr_changed(struct fscache_object *_object)
+static void cachefiles_withdraw_cookie(struct fscache_cookie *cookie)
 {
-	struct cachefiles_object *object;
-	struct cachefiles_cache *cache;
+	struct cachefiles_object *object = cookie->cache_priv;
+	struct cachefiles_cache *cache = object->volume->cache;
 	const struct cred *saved_cred;
-	struct iattr newattrs;
-	uint64_t ni_size;
-	loff_t oi_size;
-	int ret;
-
-	ni_size = _object->store_limit_l;
-
-	_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));
+	_enter("o=%x", object->debug_id);
+	cachefiles_see_object(object, cachefiles_obj_see_withdraw_cookie);
 
-	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);
-	inode_lock(d_inode(object->backer));
-
-	/* 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(&init_user_ns, object->backer, &newattrs, NULL);
-		if (ret < 0)
-			goto truncate_failed;
+	if (!list_empty(&object->cache_link)) {
+		spin_lock(&cache->object_list_lock);
+		cachefiles_see_object(object, cachefiles_obj_see_withdrawal);
+		list_del_init(&object->cache_link);
+		spin_unlock(&cache->object_list_lock);
 	}
 
-	newattrs.ia_valid = ATTR_SIZE;
-	newattrs.ia_size = ni_size;
-	ret = notify_change(&init_user_ns, object->backer, &newattrs, NULL);
-
-truncate_failed:
-	inode_unlock(d_inode(object->backer));
-	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;
+	if (object->file) {
+		cachefiles_begin_secure(cache, &saved_cred);
+		cachefiles_clean_up_object(object, cache);
+		cachefiles_end_secure(cache, saved_cred);
 	}
 
-	_leave(" = %d", ret);
-	return ret;
+	cookie->cache_priv = NULL;
+	cachefiles_put_object(object, cachefiles_obj_put_detach);
 }
 
 /*
- * Invalidate an object
+ * Invalidate the storage associated with a cookie.
  */
-static void cachefiles_invalidate_object(struct fscache_operation *op)
+static bool cachefiles_invalidate_cookie(struct fscache_cookie *cookie)
 {
-	struct cachefiles_object *object;
-	struct cachefiles_cache *cache;
-	const struct cred *saved_cred;
-	struct path path;
-	uint64_t ni_size;
-	int ret;
+	struct cachefiles_object *object = cookie->cache_priv;
+	struct file *new_file, *old_file;
+	bool old_tmpfile;
 
-	object = container_of(op->object, struct cachefiles_object, fscache);
-	cache = container_of(object->fscache.cache,
-			     struct cachefiles_cache, cache);
+	_enter("o=%x,[%llu]", object->debug_id, object->cookie->object_size);
 
-	ni_size = op->object->store_limit_l;
+	old_tmpfile = test_bit(CACHEFILES_OBJECT_USING_TMPFILE, &object->flags);
 
-	_enter("{OBJ%x},[%llu]",
-	       op->object->debug_id, (unsigned long long)ni_size);
+	if (!object->file) {
+		fscache_resume_after_invalidation(cookie);
+		_leave(" = t [light]");
+		return true;
+	}
 
-	if (object->backer) {
-		ASSERT(d_is_reg(object->backer));
+	new_file = cachefiles_create_tmpfile(object);
+	if (IS_ERR(new_file))
+		goto failed;
 
-		fscache_set_store_limit(&object->fscache, ni_size);
+	/* Substitute the VFS target */
+	_debug("sub");
+	spin_lock(&object->lock);
 
-		path.dentry = object->backer;
-		path.mnt = cache->mnt;
+	old_file = object->file;
+	object->file = new_file;
+	object->content_info = CACHEFILES_CONTENT_NO_DATA;
+	set_bit(CACHEFILES_OBJECT_USING_TMPFILE, &object->flags);
+	set_bit(FSCACHE_COOKIE_NEEDS_UPDATE, &object->cookie->flags);
 
-		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);
+	spin_unlock(&object->lock);
+	_debug("subbed");
+
+	/* Allow I/O to take place again */
+	fscache_resume_after_invalidation(cookie);
+
+	if (old_file) {
+		if (!old_tmpfile) {
+			struct cachefiles_volume *volume = object->volume;
+			struct dentry *fan = volume->fanout[(u8)cookie->key_hash];
 
-		if (ret != 0) {
-			fscache_set_store_limit(&object->fscache, 0);
-			if (ret == -EIO)
-				cachefiles_io_error_obj(object,
-							"Invalidate failed");
+			inode_lock_nested(d_inode(fan), I_MUTEX_PARENT);
+			cachefiles_bury_object(volume->cache, object, fan,
+					       old_file->f_path.dentry,
+					       FSCACHE_OBJECT_INVALIDATED);
 		}
+		fput(old_file);
 	}
 
-	fscache_op_complete(op, true);
-	_leave("");
-}
+	_leave(" = t");
+	return true;
 
-/*
- * dissociate a cache from all the pages it was backing
- */
-static void cachefiles_dissociate_pages(struct fscache_cache *cache)
-{
-	_enter("");
+failed:
+	_leave(" = f");
+	return false;
 }
 
 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,
-	.begin_read_operation	= cachefiles_begin_read_operation,
+	.acquire_volume		= cachefiles_acquire_volume,
+	.free_volume		= cachefiles_free_volume,
+	.lookup_cookie		= cachefiles_lookup_cookie,
+	.withdraw_cookie	= cachefiles_withdraw_cookie,
+	.invalidate_cookie	= cachefiles_invalidate_cookie,
+	.begin_operation	= cachefiles_begin_operation,
+	.resize_cookie		= cachefiles_resize_cookie,
+	.prepare_to_write	= cachefiles_prepare_to_write,
 };