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