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