1 /* Bind and unbind a cache from the filesystem backing it
2 *
3 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
4 * Written by David Howells (dhowells@redhat.com)
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public Licence
8 * as published by the Free Software Foundation; either version
9 * 2 of the Licence, or (at your option) any later version.
10 */
11
12 #include <linux/module.h>
13 #include <linux/init.h>
14 #include <linux/sched.h>
15 #include <linux/completion.h>
16 #include <linux/slab.h>
17 #include <linux/fs.h>
18 #include <linux/file.h>
19 #include <linux/namei.h>
20 #include <linux/mount.h>
21 #include <linux/statfs.h>
22 #include <linux/ctype.h>
23 #include "internal.h"
24
25 static int cachefiles_daemon_add_cache(struct cachefiles_cache *caches);
26
27 /*
28 * bind a directory as a cache
29 */
cachefiles_daemon_bind(struct cachefiles_cache * cache,char * args)30 int cachefiles_daemon_bind(struct cachefiles_cache *cache, char *args)
31 {
32 _enter("{%u,%u,%u,%u,%u,%u},%s",
33 cache->frun_percent,
34 cache->fcull_percent,
35 cache->fstop_percent,
36 cache->brun_percent,
37 cache->bcull_percent,
38 cache->bstop_percent,
39 args);
40
41 /* start by checking things over */
42 ASSERT(cache->fstop_percent >= 0 &&
43 cache->fstop_percent < cache->fcull_percent &&
44 cache->fcull_percent < cache->frun_percent &&
45 cache->frun_percent < 100);
46
47 ASSERT(cache->bstop_percent >= 0 &&
48 cache->bstop_percent < cache->bcull_percent &&
49 cache->bcull_percent < cache->brun_percent &&
50 cache->brun_percent < 100);
51
52 if (*args) {
53 kerror("'bind' command doesn't take an argument");
54 return -EINVAL;
55 }
56
57 if (!cache->rootdirname) {
58 kerror("No cache directory specified");
59 return -EINVAL;
60 }
61
62 /* don't permit already bound caches to be re-bound */
63 if (test_bit(CACHEFILES_READY, &cache->flags)) {
64 kerror("Cache already bound");
65 return -EBUSY;
66 }
67
68 /* make sure we have copies of the tag and dirname strings */
69 if (!cache->tag) {
70 /* the tag string is released by the fops->release()
71 * function, so we don't release it on error here */
72 cache->tag = kstrdup("CacheFiles", GFP_KERNEL);
73 if (!cache->tag)
74 return -ENOMEM;
75 }
76
77 /* add the cache */
78 return cachefiles_daemon_add_cache(cache);
79 }
80
81 /*
82 * add a cache
83 */
cachefiles_daemon_add_cache(struct cachefiles_cache * cache)84 static int cachefiles_daemon_add_cache(struct cachefiles_cache *cache)
85 {
86 struct cachefiles_object *fsdef;
87 struct path path;
88 struct kstatfs stats;
89 struct dentry *graveyard, *cachedir, *root;
90 const struct cred *saved_cred;
91 int ret;
92
93 _enter("");
94
95 /* we want to work under the module's security ID */
96 ret = cachefiles_get_security_ID(cache);
97 if (ret < 0)
98 return ret;
99
100 cachefiles_begin_secure(cache, &saved_cred);
101
102 /* allocate the root index object */
103 ret = -ENOMEM;
104
105 fsdef = kmem_cache_alloc(cachefiles_object_jar, GFP_KERNEL);
106 if (!fsdef)
107 goto error_root_object;
108
109 ASSERTCMP(fsdef->backer, ==, NULL);
110
111 atomic_set(&fsdef->usage, 1);
112 fsdef->type = FSCACHE_COOKIE_TYPE_INDEX;
113
114 _debug("- fsdef %p", fsdef);
115
116 /* look up the directory at the root of the cache */
117 ret = kern_path(cache->rootdirname, LOOKUP_DIRECTORY, &path);
118 if (ret < 0)
119 goto error_open_root;
120
121 cache->mnt = path.mnt;
122 root = path.dentry;
123
124 /* check parameters */
125 ret = -EOPNOTSUPP;
126 if (!root->d_inode ||
127 !root->d_inode->i_op ||
128 !root->d_inode->i_op->lookup ||
129 !root->d_inode->i_op->mkdir ||
130 !root->d_inode->i_op->setxattr ||
131 !root->d_inode->i_op->getxattr ||
132 !root->d_sb->s_op->statfs ||
133 !root->d_sb->s_op->sync_fs)
134 goto error_unsupported;
135
136 ret = -EROFS;
137 if (root->d_sb->s_flags & MS_RDONLY)
138 goto error_unsupported;
139
140 /* determine the security of the on-disk cache as this governs
141 * security ID of files we create */
142 ret = cachefiles_determine_cache_security(cache, root, &saved_cred);
143 if (ret < 0)
144 goto error_unsupported;
145
146 /* get the cache size and blocksize */
147 ret = vfs_statfs(&path, &stats);
148 if (ret < 0)
149 goto error_unsupported;
150
151 ret = -ERANGE;
152 if (stats.f_bsize <= 0)
153 goto error_unsupported;
154
155 ret = -EOPNOTSUPP;
156 if (stats.f_bsize > PAGE_SIZE)
157 goto error_unsupported;
158
159 cache->bsize = stats.f_bsize;
160 cache->bshift = 0;
161 if (stats.f_bsize < PAGE_SIZE)
162 cache->bshift = PAGE_SHIFT - ilog2(stats.f_bsize);
163
164 _debug("blksize %u (shift %u)",
165 cache->bsize, cache->bshift);
166
167 _debug("size %llu, avail %llu",
168 (unsigned long long) stats.f_blocks,
169 (unsigned long long) stats.f_bavail);
170
171 /* set up caching limits */
172 do_div(stats.f_files, 100);
173 cache->fstop = stats.f_files * cache->fstop_percent;
174 cache->fcull = stats.f_files * cache->fcull_percent;
175 cache->frun = stats.f_files * cache->frun_percent;
176
177 _debug("limits {%llu,%llu,%llu} files",
178 (unsigned long long) cache->frun,
179 (unsigned long long) cache->fcull,
180 (unsigned long long) cache->fstop);
181
182 stats.f_blocks >>= cache->bshift;
183 do_div(stats.f_blocks, 100);
184 cache->bstop = stats.f_blocks * cache->bstop_percent;
185 cache->bcull = stats.f_blocks * cache->bcull_percent;
186 cache->brun = stats.f_blocks * cache->brun_percent;
187
188 _debug("limits {%llu,%llu,%llu} blocks",
189 (unsigned long long) cache->brun,
190 (unsigned long long) cache->bcull,
191 (unsigned long long) cache->bstop);
192
193 /* get the cache directory and check its type */
194 cachedir = cachefiles_get_directory(cache, root, "cache");
195 if (IS_ERR(cachedir)) {
196 ret = PTR_ERR(cachedir);
197 goto error_unsupported;
198 }
199
200 fsdef->dentry = cachedir;
201 fsdef->fscache.cookie = NULL;
202
203 ret = cachefiles_check_object_type(fsdef);
204 if (ret < 0)
205 goto error_unsupported;
206
207 /* get the graveyard directory */
208 graveyard = cachefiles_get_directory(cache, root, "graveyard");
209 if (IS_ERR(graveyard)) {
210 ret = PTR_ERR(graveyard);
211 goto error_unsupported;
212 }
213
214 cache->graveyard = graveyard;
215
216 /* publish the cache */
217 fscache_init_cache(&cache->cache,
218 &cachefiles_cache_ops,
219 "%s",
220 fsdef->dentry->d_sb->s_id);
221
222 fscache_object_init(&fsdef->fscache, NULL, &cache->cache);
223
224 ret = fscache_add_cache(&cache->cache, &fsdef->fscache, cache->tag);
225 if (ret < 0)
226 goto error_add_cache;
227
228 /* done */
229 set_bit(CACHEFILES_READY, &cache->flags);
230 dput(root);
231
232 printk(KERN_INFO "CacheFiles:"
233 " File cache on %s registered\n",
234 cache->cache.identifier);
235
236 /* check how much space the cache has */
237 cachefiles_has_space(cache, 0, 0);
238 cachefiles_end_secure(cache, saved_cred);
239 return 0;
240
241 error_add_cache:
242 dput(cache->graveyard);
243 cache->graveyard = NULL;
244 error_unsupported:
245 mntput(cache->mnt);
246 cache->mnt = NULL;
247 dput(fsdef->dentry);
248 fsdef->dentry = NULL;
249 dput(root);
250 error_open_root:
251 kmem_cache_free(cachefiles_object_jar, fsdef);
252 error_root_object:
253 cachefiles_end_secure(cache, saved_cred);
254 kerror("Failed to register: %d", ret);
255 return ret;
256 }
257
258 /*
259 * unbind a cache on fd release
260 */
cachefiles_daemon_unbind(struct cachefiles_cache * cache)261 void cachefiles_daemon_unbind(struct cachefiles_cache *cache)
262 {
263 _enter("");
264
265 if (test_bit(CACHEFILES_READY, &cache->flags)) {
266 printk(KERN_INFO "CacheFiles:"
267 " File cache on %s unregistering\n",
268 cache->cache.identifier);
269
270 fscache_withdraw_cache(&cache->cache);
271 }
272
273 dput(cache->graveyard);
274 mntput(cache->mnt);
275
276 kfree(cache->rootdirname);
277 kfree(cache->secctx);
278 kfree(cache->tag);
279
280 _leave("");
281 }
282