diff options
Diffstat (limited to 'fs/cachefiles/bind.c')
| -rw-r--r-- | fs/cachefiles/bind.c | 277 |
1 files changed, 277 insertions, 0 deletions
diff --git a/fs/cachefiles/bind.c b/fs/cachefiles/bind.c new file mode 100644 index 000000000..6af790fc3 --- /dev/null +++ b/fs/cachefiles/bind.c @@ -0,0 +1,277 @@ +/* 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) { + 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; + + /* 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_op->setxattr || + !d_backing_inode(root)->i_op->getxattr || + !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(&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, 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); + + 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(""); +} |