// SPDX-License-Identifier: GPL-2.0-or-later/* Manage high-level VFS aspects of a cache. * * Copyright (C) 2007, 2021 Red Hat, Inc. All Rights Reserved. * Written by David Howells (dhowells@redhat.com) */ #include <linux/slab.h>#include <linux/statfs.h>#include <linux/namei.h>#include <trace/events/fscache.h>#include "internal.h" /* * Bring a cache online. */int cachefiles_add_cache(struct cachefiles_cache *cache){	struct fscache_cache *cache_cookie;	struct path path;	struct kstatfs stats;	struct dentry *graveyard, *cachedir, *root;	const struct cred *saved_cred;	int ret; 	_enter(""); 	cache_cookie = fscache_acquire_cache(cache->tag);	if (IS_ERR(cache_cookie))		return PTR_ERR(cache_cookie); 	/* we want to work under the module's security ID */	ret = cachefiles_get_security_ID(cache);	if (ret < 0)		goto error_getsec; 	cachefiles_begin_secure(cache, &saved_cred); 	/* 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 (is_idmapped_mnt(path.mnt)) {		pr_warn("File cache on idmapped mounts not supported");		goto error_unsupported;	} 	/* Check features of the backing filesystem:	 * - Directories must support looking up and directory creation	 * - We create tmpfiles to handle invalidation	 * - We use xattrs to store metadata	 * - We need to be able to query the amount of space available	 * - We want to be able to sync the filesystem when stopping the cache	 * - We use DIO to/from pages, so the blocksize mustn't be too big.	 */	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_op->tmpfile ||	    !(d_backing_inode(root)->i_opflags & IOP_XATTR) ||	    !root->d_sb->s_op->statfs ||	    !root->d_sb->s_op->sync_fs ||	    root->d_sb->s_blocksize > PAGE_SIZE)		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 = 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); 	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", NULL);	if (IS_ERR(cachedir)) {		ret = PTR_ERR(cachedir);		goto error_unsupported;	} 	cache->store = cachedir; 	/* get the graveyard directory */	graveyard = cachefiles_get_directory(cache, root, "graveyard", NULL);	if (IS_ERR(graveyard)) {		ret = PTR_ERR(graveyard);		goto error_unsupported;	} 	cache->graveyard = graveyard;	cache->cache = cache_cookie; 	ret = fscache_add_cache(cache_cookie, &cachefiles_cache_ops, cache);	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_cookie->name); 	/* check how much space the cache has */	cachefiles_has_space(cache, 0, 0, cachefiles_has_space_check);	cachefiles_end_secure(cache, saved_cred);	_leave(" = 0 [%px]", cache->cache);	return 0; error_add_cache:	cachefiles_put_directory(cache->graveyard);	cache->graveyard = NULL;error_unsupported:	cachefiles_put_directory(cache->store);	cache->store = NULL;	mntput(cache->mnt);	cache->mnt = NULL;	dput(root);error_open_root:	cachefiles_end_secure(cache, saved_cred);	put_cred(cache->cache_cred);	cache->cache_cred = NULL;error_getsec:	fscache_relinquish_cache(cache_cookie);	cache->cache = NULL;	pr_err("Failed to register: %d\n", ret);	return ret;} /* * See if we have space for a number of pages and/or a number of files in the * cache */int cachefiles_has_space(struct cachefiles_cache *cache,			 unsigned fnr, unsigned bnr,			 enum cachefiles_has_space_for reason){	struct kstatfs stats;	u64 b_avail, b_writing;	int ret; 	struct path path = {		.mnt	= cache->mnt,		.dentry	= cache->mnt->mnt_root,	}; 	//_enter("{%llu,%llu,%llu,%llu,%llu,%llu},%u,%u",	//       (unsigned long long) cache->frun,	//       (unsigned long long) cache->fcull,	//       (unsigned long long) cache->fstop,	//       (unsigned long long) cache->brun,	//       (unsigned long long) cache->bcull,	//       (unsigned long long) cache->bstop,	//       fnr, bnr); 	/* find out how many pages of blockdev are available */	memset(&stats, 0, sizeof(stats)); 	ret = vfs_statfs(&path, &stats);	if (ret < 0) {		trace_cachefiles_vfs_error(NULL, d_inode(path.dentry), ret,					   cachefiles_trace_statfs_error);		if (ret == -EIO)			cachefiles_io_error(cache, "statfs failed");		_leave(" = %d", ret);		return ret;	} 	b_avail = stats.f_bavail;	b_writing = atomic_long_read(&cache->b_writing);	if (b_avail > b_writing)		b_avail -= b_writing;	else		b_avail = 0; 	//_debug("avail %llu,%llu",	//       (unsigned long long)stats.f_ffree,	//       (unsigned long long)b_avail); 	/* see if there is sufficient space */	if (stats.f_ffree > fnr)		stats.f_ffree -= fnr;	else		stats.f_ffree = 0; 	if (b_avail > bnr)		b_avail -= bnr;	else		b_avail = 0; 	ret = -ENOBUFS;	if (stats.f_ffree < cache->fstop ||	    b_avail < cache->bstop)		goto stop_and_begin_cull; 	ret = 0;	if (stats.f_ffree < cache->fcull ||	    b_avail < cache->bcull)		goto begin_cull; 	if (test_bit(CACHEFILES_CULLING, &cache->flags) &&	    stats.f_ffree >= cache->frun &&	    b_avail >= cache->brun &&	    test_and_clear_bit(CACHEFILES_CULLING, &cache->flags)	    ) {		_debug("cease culling");		cachefiles_state_changed(cache);	} 	//_leave(" = 0");	return 0; stop_and_begin_cull:	switch (reason) {	case cachefiles_has_space_for_write:		fscache_count_no_write_space();		break;	case cachefiles_has_space_for_create:		fscache_count_no_create_space();		break;	default:		break;	}begin_cull:	if (!test_and_set_bit(CACHEFILES_CULLING, &cache->flags)) {		_debug("### CULL CACHE ###");		cachefiles_state_changed(cache);	} 	_leave(" = %d", ret);	return ret;} /* * Mark all the objects as being out of service and queue them all for cleanup. */static void cachefiles_withdraw_objects(struct cachefiles_cache *cache){	struct cachefiles_object *object;	unsigned int count = 0; 	_enter(""); 	spin_lock(&cache->object_list_lock); 	while (!list_empty(&cache->object_list)) {		object = list_first_entry(&cache->object_list,					  struct cachefiles_object, cache_link);		cachefiles_see_object(object, cachefiles_obj_see_withdrawal);		list_del_init(&object->cache_link);		fscache_withdraw_cookie(object->cookie);		count++;		if ((count & 63) == 0) {			spin_unlock(&cache->object_list_lock);			cond_resched();			spin_lock(&cache->object_list_lock);		}	} 	spin_unlock(&cache->object_list_lock);	_leave(" [%u objs]", count);} /* * Withdraw fscache volumes. */static void cachefiles_withdraw_fscache_volumes(struct cachefiles_cache *cache){	struct list_head *cur;	struct cachefiles_volume *volume;	struct fscache_volume *vcookie; 	_enter("");retry:	spin_lock(&cache->object_list_lock);	list_for_each(cur, &cache->volumes) {		volume = list_entry(cur, struct cachefiles_volume, cache_link); 		if (atomic_read(&volume->vcookie->n_accesses) == 0)			continue; 		vcookie = fscache_try_get_volume(volume->vcookie,						 fscache_volume_get_withdraw);		if (vcookie) {			spin_unlock(&cache->object_list_lock);			fscache_withdraw_volume(vcookie);			fscache_put_volume(vcookie, fscache_volume_put_withdraw);			goto retry;		}	}	spin_unlock(&cache->object_list_lock); 	_leave("");} /* * Withdraw cachefiles volumes. */static void cachefiles_withdraw_volumes(struct cachefiles_cache *cache){	_enter(""); 	for (;;) {		struct fscache_volume *vcookie = NULL;		struct cachefiles_volume *volume = NULL; 		spin_lock(&cache->object_list_lock);		if (!list_empty(&cache->volumes)) {			volume = list_first_entry(&cache->volumes,						  struct cachefiles_volume, cache_link);			vcookie = fscache_try_get_volume(volume->vcookie,							 fscache_volume_get_withdraw);			if (!vcookie) {				spin_unlock(&cache->object_list_lock);				cpu_relax();				continue;			}			list_del_init(&volume->cache_link);		}		spin_unlock(&cache->object_list_lock);		if (!volume)			break; 		cachefiles_withdraw_volume(volume);		fscache_put_volume(vcookie, fscache_volume_put_withdraw);	} 	_leave("");} /* * Sync a cache to backing disk. */static void cachefiles_sync_cache(struct cachefiles_cache *cache){	const struct cred *saved_cred;	int ret; 	_enter("%s", cache->cache->name); 	/* 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);} /* * Withdraw cache objects. */void cachefiles_withdraw_cache(struct cachefiles_cache *cache){	struct fscache_cache *fscache = cache->cache; 	pr_info("File cache on %s unregistering\n", fscache->name); 	fscache_withdraw_cache(fscache);	cachefiles_withdraw_fscache_volumes(cache); 	/* we now have to destroy all the active objects pertaining to this	 * cache - which we do by passing them off to thread pool to be	 * disposed of */	cachefiles_withdraw_objects(cache);	fscache_wait_for_objects(fscache); 	cachefiles_withdraw_volumes(cache);	cachefiles_sync_cache(cache);	cache->cache = NULL;	fscache_relinquish_cache(fscache);}