blob: 3797e0077b356b4f3c0c7400cd5918ca7f4e8f1a [file] [log] [blame]
David Howells9ae326a2009-04-03 16:42:41 +01001/* 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
25static int cachefiles_daemon_add_cache(struct cachefiles_cache *caches);
26
27/*
28 * bind a directory as a cache
29 */
30int 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 */
84static int cachefiles_daemon_add_cache(struct cachefiles_cache *cache)
85{
86 struct cachefiles_object *fsdef;
87 struct nameidata nd;
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 memset(&nd, 0, sizeof(nd));
118
119 ret = path_lookup(cache->rootdirname, LOOKUP_DIRECTORY, &nd);
120 if (ret < 0)
121 goto error_open_root;
122
123 cache->mnt = mntget(nd.path.mnt);
124 root = dget(nd.path.dentry);
125 path_put(&nd.path);
126
127 /* check parameters */
128 ret = -EOPNOTSUPP;
129 if (!root->d_inode ||
130 !root->d_inode->i_op ||
131 !root->d_inode->i_op->lookup ||
132 !root->d_inode->i_op->mkdir ||
133 !root->d_inode->i_op->setxattr ||
134 !root->d_inode->i_op->getxattr ||
135 !root->d_sb ||
136 !root->d_sb->s_op ||
137 !root->d_sb->s_op->statfs ||
138 !root->d_sb->s_op->sync_fs)
139 goto error_unsupported;
140
141 ret = -EROFS;
142 if (root->d_sb->s_flags & MS_RDONLY)
143 goto error_unsupported;
144
145 /* determine the security of the on-disk cache as this governs
146 * security ID of files we create */
147 ret = cachefiles_determine_cache_security(cache, root, &saved_cred);
148 if (ret < 0)
149 goto error_unsupported;
150
151 /* get the cache size and blocksize */
152 ret = vfs_statfs(root, &stats);
153 if (ret < 0)
154 goto error_unsupported;
155
156 ret = -ERANGE;
157 if (stats.f_bsize <= 0)
158 goto error_unsupported;
159
160 ret = -EOPNOTSUPP;
161 if (stats.f_bsize > PAGE_SIZE)
162 goto error_unsupported;
163
164 cache->bsize = stats.f_bsize;
165 cache->bshift = 0;
166 if (stats.f_bsize < PAGE_SIZE)
167 cache->bshift = PAGE_SHIFT - ilog2(stats.f_bsize);
168
169 _debug("blksize %u (shift %u)",
170 cache->bsize, cache->bshift);
171
172 _debug("size %llu, avail %llu",
173 (unsigned long long) stats.f_blocks,
174 (unsigned long long) stats.f_bavail);
175
176 /* set up caching limits */
177 do_div(stats.f_files, 100);
178 cache->fstop = stats.f_files * cache->fstop_percent;
179 cache->fcull = stats.f_files * cache->fcull_percent;
180 cache->frun = stats.f_files * cache->frun_percent;
181
182 _debug("limits {%llu,%llu,%llu} files",
183 (unsigned long long) cache->frun,
184 (unsigned long long) cache->fcull,
185 (unsigned long long) cache->fstop);
186
187 stats.f_blocks >>= cache->bshift;
188 do_div(stats.f_blocks, 100);
189 cache->bstop = stats.f_blocks * cache->bstop_percent;
190 cache->bcull = stats.f_blocks * cache->bcull_percent;
191 cache->brun = stats.f_blocks * cache->brun_percent;
192
193 _debug("limits {%llu,%llu,%llu} blocks",
194 (unsigned long long) cache->brun,
195 (unsigned long long) cache->bcull,
196 (unsigned long long) cache->bstop);
197
198 /* get the cache directory and check its type */
199 cachedir = cachefiles_get_directory(cache, root, "cache");
200 if (IS_ERR(cachedir)) {
201 ret = PTR_ERR(cachedir);
202 goto error_unsupported;
203 }
204
205 fsdef->dentry = cachedir;
206 fsdef->fscache.cookie = NULL;
207
208 ret = cachefiles_check_object_type(fsdef);
209 if (ret < 0)
210 goto error_unsupported;
211
212 /* get the graveyard directory */
213 graveyard = cachefiles_get_directory(cache, root, "graveyard");
214 if (IS_ERR(graveyard)) {
215 ret = PTR_ERR(graveyard);
216 goto error_unsupported;
217 }
218
219 cache->graveyard = graveyard;
220
221 /* publish the cache */
222 fscache_init_cache(&cache->cache,
223 &cachefiles_cache_ops,
224 "%s",
225 fsdef->dentry->d_sb->s_id);
226
227 fscache_object_init(&fsdef->fscache, NULL, &cache->cache);
228
229 ret = fscache_add_cache(&cache->cache, &fsdef->fscache, cache->tag);
230 if (ret < 0)
231 goto error_add_cache;
232
233 /* done */
234 set_bit(CACHEFILES_READY, &cache->flags);
235 dput(root);
236
237 printk(KERN_INFO "CacheFiles:"
238 " File cache on %s registered\n",
239 cache->cache.identifier);
240
241 /* check how much space the cache has */
242 cachefiles_has_space(cache, 0, 0);
243 cachefiles_end_secure(cache, saved_cred);
244 return 0;
245
246error_add_cache:
247 dput(cache->graveyard);
248 cache->graveyard = NULL;
249error_unsupported:
250 mntput(cache->mnt);
251 cache->mnt = NULL;
252 dput(fsdef->dentry);
253 fsdef->dentry = NULL;
254 dput(root);
255error_open_root:
256 kmem_cache_free(cachefiles_object_jar, fsdef);
257error_root_object:
258 cachefiles_end_secure(cache, saved_cred);
259 kerror("Failed to register: %d", ret);
260 return ret;
261}
262
263/*
264 * unbind a cache on fd release
265 */
266void cachefiles_daemon_unbind(struct cachefiles_cache *cache)
267{
268 _enter("");
269
270 if (test_bit(CACHEFILES_READY, &cache->flags)) {
271 printk(KERN_INFO "CacheFiles:"
272 " File cache on %s unregistering\n",
273 cache->cache.identifier);
274
275 fscache_withdraw_cache(&cache->cache);
276 }
277
278 dput(cache->graveyard);
279 mntput(cache->mnt);
280
281 kfree(cache->rootdirname);
282 kfree(cache->secctx);
283 kfree(cache->tag);
284
285 _leave("");
286}