/* 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) * * 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/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 "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) { kerror("'bind' command doesn't take an argument"); return -EINVAL; } if (!cache->rootdirname) { kerror("No cache directory specified"); return -EINVAL; } /* don't permit already bound caches to be re-bound */ if (test_bit(CACHEFILES_READY, &cache->flags)) { kerror("Cache already bound"); 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; /* check parameters */ ret = -EOPNOTSUPP; if (!root->d_inode || !root->d_inode->i_op || !root->d_inode->i_op->lookup || !root->d_inode->i_op->mkdir || !root->d_inode->i_op->setxattr || !root->d_inode->i_op->getxattr || !root->d_sb || !root->d_sb->s_op || !root->d_sb->s_op->statfs || !root->d_sb->s_op->sync_fs) goto error_unsupported; ret = -EROFS; if (root->d_sb->s_flags & MS_RDONLY) 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(root, &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, NULL, &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); printk(KERN_INFO "CacheFiles:" " 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); kerror("Failed to register: %d", 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)) { printk(KERN_INFO "CacheFiles:" " 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(""); }