// SPDX-License-Identifier: GPL-2.0-or-later/* Bind and unbind a cache from the filesystem backing it * * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved. * Written by David Howells (dhowells@redhat.com) */ #include <linux/module.h>#include <linux/init.h>#include <linux/sched.h>#include <linux/completion.h>#include <linux/slab.h>#include <linux/fs.h>#include <linux/file.h>#include <linux/namei.h>#include <linux/mount.h>#include <linux/statfs.h>#include <linux/ctype.h>#include <linux/xattr.h>#include "internal.h" static int cachefiles_daemon_add_cache(struct cachefiles_cache *caches); /* * bind a directory as a cache */int cachefiles_daemon_bind(struct cachefiles_cache *cache, char *args){	_enter("{%u,%u,%u,%u,%u,%u},%s",	       cache->frun_percent,	       cache->fcull_percent,	       cache->fstop_percent,	       cache->brun_percent,	       cache->bcull_percent,	       cache->bstop_percent,	       args); 	/* start by checking things over */	ASSERT(cache->fstop_percent >= 0 &&	       cache->fstop_percent < cache->fcull_percent &&	       cache->fcull_percent < cache->frun_percent &&	       cache->frun_percent  < 100); 	ASSERT(cache->bstop_percent >= 0 &&	       cache->bstop_percent < cache->bcull_percent &&	       cache->bcull_percent < cache->brun_percent &&	       cache->brun_percent  < 100); 	if (*args) {		pr_err("'bind' command doesn't take an argument\n");		return -EINVAL;	} 	if (!cache->rootdirname) {		pr_err("No cache directory specified\n");		return -EINVAL;	} 	/* don't permit already bound caches to be re-bound */	if (test_bit(CACHEFILES_READY, &cache->flags)) {		pr_err("Cache already bound\n");		return -EBUSY;	} 	/* make sure we have copies of the tag and dirname strings */	if (!cache->tag) {		/* the tag string is released by the fops->release()		 * function, so we don't release it on error here */		cache->tag = kstrdup("CacheFiles", GFP_KERNEL);		if (!cache->tag)			return -ENOMEM;	} 	/* add the cache */	return cachefiles_daemon_add_cache(cache);} /* * add a cache */static int cachefiles_daemon_add_cache(struct cachefiles_cache *cache){	struct cachefiles_object *fsdef;	struct path path;	struct kstatfs stats;	struct dentry *graveyard, *cachedir, *root;	const struct cred *saved_cred;	int ret; 	_enter(""); 	/* we want to work under the module's security ID */	ret = cachefiles_get_security_ID(cache);	if (ret < 0)		return ret; 	cachefiles_begin_secure(cache, &saved_cred); 	/* allocate the root index object */	ret = -ENOMEM; 	fsdef = kmem_cache_alloc(cachefiles_object_jar, GFP_KERNEL);	if (!fsdef)		goto error_root_object; 	ASSERTCMP(fsdef->backer, ==, NULL); 	atomic_set(&fsdef->usage, 1);	fsdef->type = FSCACHE_COOKIE_TYPE_INDEX; 	_debug("- fsdef %p", fsdef); 	/* look up the directory at the root of the cache */	ret = kern_path(cache->rootdirname, LOOKUP_DIRECTORY, &path);	if (ret < 0)		goto error_open_root; 	cache->mnt = path.mnt;	root = path.dentry; 	ret = -EINVAL;	if (mnt_user_ns(path.mnt) != &init_user_ns) {		pr_warn("File cache on idmapped mounts not supported");		goto error_unsupported;	} 	/* check parameters */	ret = -EOPNOTSUPP;	if (d_is_negative(root) ||	    !d_backing_inode(root)->i_op->lookup ||	    !d_backing_inode(root)->i_op->mkdir ||	    !(d_backing_inode(root)->i_opflags & IOP_XATTR) ||	    !root->d_sb->s_op->statfs ||	    !root->d_sb->s_op->sync_fs)		goto error_unsupported; 	ret = -EROFS;	if (sb_rdonly(root->d_sb))		goto error_unsupported; 	/* determine the security of the on-disk cache as this governs	 * security ID of files we create */	ret = cachefiles_determine_cache_security(cache, root, &saved_cred);	if (ret < 0)		goto error_unsupported; 	/* get the cache size and blocksize */	ret = vfs_statfs(&path, &stats);	if (ret < 0)		goto error_unsupported; 	ret = -ERANGE;	if (stats.f_bsize <= 0)		goto error_unsupported; 	ret = -EOPNOTSUPP;	if (stats.f_bsize > PAGE_SIZE)		goto error_unsupported; 	cache->bsize = stats.f_bsize;	cache->bshift = 0;	if (stats.f_bsize < PAGE_SIZE)		cache->bshift = PAGE_SHIFT - ilog2(stats.f_bsize); 	_debug("blksize %u (shift %u)",	       cache->bsize, cache->bshift); 	_debug("size %llu, avail %llu",	       (unsigned long long) stats.f_blocks,	       (unsigned long long) stats.f_bavail); 	/* set up caching limits */	do_div(stats.f_files, 100);	cache->fstop = stats.f_files * cache->fstop_percent;	cache->fcull = stats.f_files * cache->fcull_percent;	cache->frun  = stats.f_files * cache->frun_percent; 	_debug("limits {%llu,%llu,%llu} files",	       (unsigned long long) cache->frun,	       (unsigned long long) cache->fcull,	       (unsigned long long) cache->fstop); 	stats.f_blocks >>= cache->bshift;	do_div(stats.f_blocks, 100);	cache->bstop = stats.f_blocks * cache->bstop_percent;	cache->bcull = stats.f_blocks * cache->bcull_percent;	cache->brun  = stats.f_blocks * cache->brun_percent; 	_debug("limits {%llu,%llu,%llu} blocks",	       (unsigned long long) cache->brun,	       (unsigned long long) cache->bcull,	       (unsigned long long) cache->bstop); 	/* get the cache directory and check its type */	cachedir = cachefiles_get_directory(cache, root, "cache");	if (IS_ERR(cachedir)) {		ret = PTR_ERR(cachedir);		goto error_unsupported;	} 	fsdef->dentry = cachedir;	fsdef->fscache.cookie = NULL; 	ret = cachefiles_check_object_type(fsdef);	if (ret < 0)		goto error_unsupported; 	/* get the graveyard directory */	graveyard = cachefiles_get_directory(cache, root, "graveyard");	if (IS_ERR(graveyard)) {		ret = PTR_ERR(graveyard);		goto error_unsupported;	} 	cache->graveyard = graveyard; 	/* publish the cache */	fscache_init_cache(&cache->cache,			   &cachefiles_cache_ops,			   "%s",			   fsdef->dentry->d_sb->s_id); 	fscache_object_init(&fsdef->fscache, &fscache_fsdef_index,			    &cache->cache); 	ret = fscache_add_cache(&cache->cache, &fsdef->fscache, cache->tag);	if (ret < 0)		goto error_add_cache; 	/* done */	set_bit(CACHEFILES_READY, &cache->flags);	dput(root); 	pr_info("File cache on %s registered\n", cache->cache.identifier); 	/* check how much space the cache has */	cachefiles_has_space(cache, 0, 0);	cachefiles_end_secure(cache, saved_cred);	return 0; error_add_cache:	dput(cache->graveyard);	cache->graveyard = NULL;error_unsupported:	mntput(cache->mnt);	cache->mnt = NULL;	dput(fsdef->dentry);	fsdef->dentry = NULL;	dput(root);error_open_root:	kmem_cache_free(cachefiles_object_jar, fsdef);error_root_object:	cachefiles_end_secure(cache, saved_cred);	pr_err("Failed to register: %d\n", ret);	return ret;} /* * unbind a cache on fd release */void cachefiles_daemon_unbind(struct cachefiles_cache *cache){	_enter(""); 	if (test_bit(CACHEFILES_READY, &cache->flags)) {		pr_info("File cache on %s unregistering\n",			cache->cache.identifier); 		fscache_withdraw_cache(&cache->cache);	} 	dput(cache->graveyard);	mntput(cache->mnt); 	kfree(cache->rootdirname);	kfree(cache->secctx);	kfree(cache->tag); 	_leave("");}