original development tree for Linux kernel GTP module; now long in mainline.
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/* 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->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);
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("");
}