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TOMOYO Linux Cross Reference
Linux/fs/cachefiles/bind.c

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

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