// SPDX-License-Identifier: GPL-2.0-or-later/* FS-Cache interface to CacheFiles * * 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" static atomic_t cachefiles_object_debug_id; /* * Allocate a cache object record. */staticstruct cachefiles_object *cachefiles_alloc_object(struct fscache_cookie *cookie){	struct fscache_volume *vcookie = cookie->volume;	struct cachefiles_volume *volume = vcookie->cache_priv;	struct cachefiles_object *object; 	_enter("{%s},%x,", vcookie->key, cookie->debug_id); 	object = kmem_cache_zalloc(cachefiles_object_jar, GFP_KERNEL);	if (!object)		return NULL; 	refcount_set(&object->ref, 1); 	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); 	fscache_count_object(vcookie->cache);	trace_cachefiles_ref(object->debug_id, cookie->debug_id, 1,			     cachefiles_obj_new);	return object;} /* * Note that an object has been seen. */void cachefiles_see_object(struct cachefiles_object *object,			   enum cachefiles_obj_ref_trace why){	trace_cachefiles_ref(object->debug_id, object->cookie->debug_id,			     refcount_read(&object->ref), why);} /* * Increment the usage count on an object; */struct cachefiles_object *cachefiles_grab_object(struct cachefiles_object *object,						 enum cachefiles_obj_ref_trace why){	int r; 	__refcount_inc(&object->ref, &r);	trace_cachefiles_ref(object->debug_id, object->cookie->debug_id, r, why);	return object;} /* * dispose of a reference to an object */void cachefiles_put_object(struct cachefiles_object *object,			   enum cachefiles_obj_ref_trace why){	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); 		kfree(object->d_name); 		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);	} 	_leave("");} /* * 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 int cachefiles_adjust_size(struct cachefiles_object *object){	struct iattr newattrs;	struct file *file = object->file;	uint64_t ni_size;	loff_t oi_size;	int ret; 	ni_size = object->cookie->object_size;	ni_size = round_up(ni_size, CACHEFILES_DIO_BLOCK_SIZE); 	_enter("{OBJ%x},[%llu]",	       object->debug_id, (unsigned long long) ni_size); 	if (!file)		return -ENOBUFS; 	oi_size = i_size_read(file_inode(file));	if (oi_size == ni_size)		return 0; 	inode_lock(file_inode(file)); 	/* 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(&nop_mnt_idmap, file->f_path.dentry,					    &newattrs, NULL);		if (ret < 0)			goto truncate_failed;	} 	newattrs.ia_valid = ATTR_SIZE;	newattrs.ia_size = ni_size;	ret = cachefiles_inject_write_error();	if (ret == 0)		ret = notify_change(&nop_mnt_idmap, file->f_path.dentry,				    &newattrs, NULL); truncate_failed:	inode_unlock(file_inode(file)); 	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;	} 	_leave(" = %d", ret);	return ret;} /* * Attempt to look up the nominated node in this cache */static bool cachefiles_lookup_cookie(struct fscache_cookie *cookie){	struct cachefiles_object *object;	struct cachefiles_cache *cache = cookie->volume->cache->cache_priv;	const struct cred *saved_cred;	bool success; 	object = cachefiles_alloc_object(cookie);	if (!object)		goto fail; 	_enter("{OBJ%x}", object->debug_id); 	if (!cachefiles_cook_key(object))		goto fail_put; 	cookie->cache_priv = object; 	cachefiles_begin_secure(cache, &saved_cred); 	success = cachefiles_look_up_object(object);	if (!success)		goto fail_withdraw; 	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); 	cachefiles_end_secure(cache, saved_cred);	_leave(" = t");	return true; 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; fail_put:	cachefiles_put_object(object, cachefiles_obj_put_alloc_fail);fail:	return false;} /* * Shorten the backing object to discard any dirty data and free up * any unused granules. */static bool cachefiles_shorten_object(struct cachefiles_object *object,				      struct file *file, loff_t new_size){	struct cachefiles_cache *cache = object->volume->cache;	struct inode *inode = file_inode(file);	loff_t i_size, dio_size;	int ret; 	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 (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 - new_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;		}	} 	return true;} /* * Resize the backing object. */static void cachefiles_resize_cookie(struct netfs_cache_resources *cres,				     loff_t new_size){	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;	struct file *file = cachefiles_cres_file(cres);	loff_t old_size = cookie->object_size; 	_enter("%llu->%llu", old_size, new_size); 	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;	} 	/* 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;} /* * Commit changes to the object as we drop it. */static void cachefiles_commit_object(struct cachefiles_object *object,				     struct cachefiles_cache *cache){	bool update = false; 	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); 	if (test_bit(CACHEFILES_OBJECT_USING_TMPFILE, &object->flags))		cachefiles_commit_tmpfile(cache, object);} /* * 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);	} 	cachefiles_unmark_inode_in_use(object, object->file);	if (object->file) {		fput(object->file);		object->file = NULL;	}} /* * Withdraw caching for a cookie. */static void cachefiles_withdraw_cookie(struct fscache_cookie *cookie){	struct cachefiles_object *object = cookie->cache_priv;	struct cachefiles_cache *cache = object->volume->cache;	const struct cred *saved_cred; 	_enter("o=%x", object->debug_id);	cachefiles_see_object(object, cachefiles_obj_see_withdraw_cookie); 	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);	} 	cachefiles_ondemand_clean_object(object); 	if (object->file) {		cachefiles_begin_secure(cache, &saved_cred);		cachefiles_clean_up_object(object, cache);		cachefiles_end_secure(cache, saved_cred);	} 	cookie->cache_priv = NULL;	cachefiles_put_object(object, cachefiles_obj_put_detach);} /* * Invalidate the storage associated with a cookie. */static bool cachefiles_invalidate_cookie(struct fscache_cookie *cookie){	struct cachefiles_object *object = cookie->cache_priv;	struct file *new_file, *old_file;	bool old_tmpfile; 	_enter("o=%x,[%llu]", object->debug_id, object->cookie->object_size); 	old_tmpfile = test_bit(CACHEFILES_OBJECT_USING_TMPFILE, &object->flags); 	if (!object->file) {		fscache_resume_after_invalidation(cookie);		_leave(" = t [light]");		return true;	} 	new_file = cachefiles_create_tmpfile(object);	if (IS_ERR(new_file))		goto failed; 	/* Substitute the VFS target */	_debug("sub");	spin_lock(&object->lock); 	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); 	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]; 			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);	} 	_leave(" = t");	return true; failed:	_leave(" = f");	return false;} const struct fscache_cache_ops cachefiles_cache_ops = {	.name			= "cachefiles",	.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,};