fs/afs/super.c

   1 /* AFS superblock handling
   2  *
   3  * Copyright (c) 2002, 2007 Red Hat, Inc. All rights reserved.
   4  *
   5  * This software may be freely redistributed under the terms of the
   6  * GNU General Public License.
   7  *
   8  * You should have received a copy of the GNU General Public License
   9  * along with this program; if not, write to the Free Software
  10  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  11  *
  12  * Authors: David Howells <dhowells@redhat.com>
  13  *          David Woodhouse <dwmw2@redhat.com>
  14  *
  15  */
  16
  17 #include <linux/kernel.h>
  18 #include <linux/module.h>
  19 #include <linux/init.h>
  20 #include <linux/slab.h>
  21 #include <linux/fs.h>
  22 #include <linux/pagemap.h>
  23 #include "internal.h"
  24
  25 #define AFS_FS_MAGIC 0x6B414653 /* 'kAFS' */
  26
  27 static void afs_i_init_once(void *foo, struct kmem_cache *cachep,
  28                             unsigned long flags);
  29
  30 static int afs_get_sb(struct file_system_type *fs_type,
  31                       int flags, const char *dev_name,
  32                       void *data, struct vfsmount *mnt);
  33
  34 static struct inode *afs_alloc_inode(struct super_block *sb);
  35
  36 static void afs_put_super(struct super_block *sb);
  37
  38 static void afs_destroy_inode(struct inode *inode);
  39
  40 struct file_system_type afs_fs_type = {
  41         .owner          = THIS_MODULE,
  42         .name           = "afs",
  43         .get_sb         = afs_get_sb,
  44         .kill_sb        = kill_anon_super,
  45         .fs_flags       = FS_BINARY_MOUNTDATA,
  46 };
  47
  48 static const struct super_operations afs_super_ops = {
  49         .statfs         = simple_statfs,
  50         .alloc_inode    = afs_alloc_inode,
  51         .drop_inode     = generic_delete_inode,
  52         .destroy_inode  = afs_destroy_inode,
  53         .clear_inode    = afs_clear_inode,
  54         .umount_begin   = afs_umount_begin,
  55         .put_super      = afs_put_super,
  56 };
  57
  58 static struct kmem_cache *afs_inode_cachep;
  59 static atomic_t afs_count_active_inodes;
  60
  61 /*
  62  * initialise the filesystem
  63  */
  64 int __init afs_fs_init(void)
  65 {
  66         int ret;
  67
  68         _enter("");
  69
  70         /* create ourselves an inode cache */
  71         atomic_set(&afs_count_active_inodes, 0);
  72
  73         ret = -ENOMEM;
  74         afs_inode_cachep = kmem_cache_create("afs_inode_cache",
  75                                              sizeof(struct afs_vnode),
  76                                              0,
  77                                              SLAB_HWCACHE_ALIGN,
  78                                              afs_i_init_once,
  79                                              NULL);
  80         if (!afs_inode_cachep) {
  81                 printk(KERN_NOTICE "kAFS: Failed to allocate inode cache\n");
  82                 return ret;
  83         }
  84
  85         /* now export our filesystem to lesser mortals */
  86         ret = register_filesystem(&afs_fs_type);
  87         if (ret < 0) {
  88                 kmem_cache_destroy(afs_inode_cachep);
  89                 _leave(" = %d", ret);
  90                 return ret;
  91         }
  92
  93         _leave(" = 0");
  94         return 0;
  95 }
  96
  97 /*
  98  * clean up the filesystem
  99  */
 100 void __exit afs_fs_exit(void)
 101 {
 102         _enter("");
 103
 104         afs_mntpt_kill_timer();
 105         unregister_filesystem(&afs_fs_type);
 106
 107         if (atomic_read(&afs_count_active_inodes) != 0) {
 108                 printk("kAFS: %d active inode objects still present\n",
 109                        atomic_read(&afs_count_active_inodes));
 110                 BUG();
 111         }
 112
 113         kmem_cache_destroy(afs_inode_cachep);
 114         _leave("");
 115 }
 116
 117 /*
 118  * check that an argument has a value
 119  */
 120 static int want_arg(char **_value, const char *option)
 121 {
 122         if (!_value || !*_value || !**_value) {
 123                 printk(KERN_NOTICE "kAFS: %s: argument missing\n", option);
 124                 return 0;
 125         }
 126         return 1;
 127 }
 128
 129 /*
 130  * check that there's no subsequent value
 131  */
 132 static int want_no_value(char *const *_value, const char *option)
 133 {
 134         if (*_value && **_value) {
 135                 printk(KERN_NOTICE "kAFS: %s: Invalid argument: %s\n",
 136                        option, *_value);
 137                 return 0;
 138         }
 139         return 1;
 140 }
 141
 142 /*
 143  * parse the mount options
 144  * - this function has been shamelessly adapted from the ext3 fs which
 145  *   shamelessly adapted it from the msdos fs
 146  */
 147 static int afs_parse_options(struct afs_mount_params *params,
 148                              char *options, const char **devname)
 149 {
 150         struct afs_cell *cell;
 151         char *key, *value;
 152         int ret;
 153
 154         _enter("%s", options);
 155
 156         options[PAGE_SIZE - 1] = 0;
 157
 158         ret = 0;
 159         while ((key = strsep(&options, ","))) {
 160                 value = strchr(key, '=');
 161                 if (value)
 162                         *value++ = 0;
 163
 164                 _debug("kAFS: KEY: %s, VAL:%s", key, value ?: "-");
 165
 166                 if (strcmp(key, "rwpath") == 0) {
 167                         if (!want_no_value(&value, "rwpath"))
 168                                 return -EINVAL;
 169                         params->rwpath = 1;
 170                 } else if (strcmp(key, "vol") == 0) {
 171                         if (!want_arg(&value, "vol"))
 172                                 return -EINVAL;
 173                         *devname = value;
 174                 } else if (strcmp(key, "cell") == 0) {
 175                         if (!want_arg(&value, "cell"))
 176                                 return -EINVAL;
 177                         cell = afs_cell_lookup(value, strlen(value));
 178                         if (IS_ERR(cell))
 179                                 return PTR_ERR(cell);
 180                         afs_put_cell(params->cell);
 181                         params->cell = cell;
 182                 } else {
 183                         printk("kAFS: Unknown mount option: '%s'\n",  key);
 184                         ret = -EINVAL;
 185                         goto error;
 186                 }
 187         }
 188
 189         ret = 0;
 190 error:
 191         _leave(" = %d", ret);
 192         return ret;
 193 }
 194
 195 /*
 196  * parse a device name to get cell name, volume name, volume type and R/W
 197  * selector
 198  * - this can be one of the following:
 199  *      "%[cell:]volume[.]"             R/W volume
 200  *      "#[cell:]volume[.]"             R/O or R/W volume (rwpath=0),
 201  *                                       or R/W (rwpath=1) volume
 202  *      "%[cell:]volume.readonly"       R/O volume
 203  *      "#[cell:]volume.readonly"       R/O volume
 204  *      "%[cell:]volume.backup"         Backup volume
 205  *      "#[cell:]volume.backup"         Backup volume
 206  */
 207 static int afs_parse_device_name(struct afs_mount_params *params,
 208                                  const char *name)
 209 {
 210         struct afs_cell *cell;
 211         const char *cellname, *suffix;
 212         int cellnamesz;
 213
 214         _enter(",%s", name);
 215
 216         if (!name) {
 217                 printk(KERN_ERR "kAFS: no volume name specified\n");
 218                 return -EINVAL;
 219         }
 220
 221         if ((name[0] != '%' && name[0] != '#') || !name[1]) {
 222                 printk(KERN_ERR "kAFS: unparsable volume name\n");
 223                 return -EINVAL;
 224         }
 225
 226         /* determine the type of volume we're looking for */
 227         params->type = AFSVL_ROVOL;
 228         params->force = false;
 229         if (params->rwpath || name[0] == '%') {
 230                 params->type = AFSVL_RWVOL;
 231                 params->force = true;
 232         }
 233         name++;
 234
 235         /* split the cell name out if there is one */
 236         params->volname = strchr(name, ':');
 237         if (params->volname) {
 238                 cellname = name;
 239                 cellnamesz = params->volname - name;
 240                 params->volname++;
 241         } else {
 242                 params->volname = name;
 243                 cellname = NULL;
 244                 cellnamesz = 0;
 245         }
 246
 247         /* the volume type is further affected by a possible suffix */
 248         suffix = strrchr(params->volname, '.');
 249         if (suffix) {
 250                 if (strcmp(suffix, ".readonly") == 0) {
 251                         params->type = AFSVL_ROVOL;
 252                         params->force = true;
 253                 } else if (strcmp(suffix, ".backup") == 0) {
 254                         params->type = AFSVL_BACKVOL;
 255                         params->force = true;
 256                 } else if (suffix[1] == 0) {
 257                 } else {
 258                         suffix = NULL;
 259                 }
 260         }
 261
 262         params->volnamesz = suffix ?
 263                 suffix - params->volname : strlen(params->volname);
 264
 265         _debug("cell %*.*s [%p]",
 266                cellnamesz, cellnamesz, cellname ?: "", params->cell);
 267
 268         /* lookup the cell record */
 269         if (cellname || !params->cell) {
 270                 cell = afs_cell_lookup(cellname, cellnamesz);
 271                 if (IS_ERR(cell)) {
 272                         printk(KERN_ERR "kAFS: unable to lookup cell '%s'\n",
 273                                cellname ?: "");
 274                         return PTR_ERR(cell);
 275                 }
 276                 afs_put_cell(params->cell);
 277                 params->cell = cell;
 278         }
 279
 280         _debug("CELL:%s [%p] VOLUME:%*.*s SUFFIX:%s TYPE:%d%s",
 281                params->cell->name, params->cell,
 282                params->volnamesz, params->volnamesz, params->volname,
 283                suffix ?: "-", params->type, params->force ? " FORCE" : "");
 284
 285         return 0;
 286 }
 287
 288 /*
 289  * check a superblock to see if it's the one we're looking for
 290  */
 291 static int afs_test_super(struct super_block *sb, void *data)
 292 {
 293         struct afs_mount_params *params = data;
 294         struct afs_super_info *as = sb->s_fs_info;
 295
 296         return as->volume == params->volume;
 297 }
 298
 299 /*
 300  * fill in the superblock
 301  */
 302 static int afs_fill_super(struct super_block *sb, void *data)
 303 {
 304         struct afs_mount_params *params = data;
 305         struct afs_super_info *as = NULL;
 306         struct afs_fid fid;
 307         struct dentry *root = NULL;
 308         struct inode *inode = NULL;
 309         int ret;
 310
 311         _enter("");
 312
 313         /* allocate a superblock info record */
 314         as = kzalloc(sizeof(struct afs_super_info), GFP_KERNEL);
 315         if (!as) {
 316                 _leave(" = -ENOMEM");
 317                 return -ENOMEM;
 318         }
 319
 320         afs_get_volume(params->volume);
 321         as->volume = params->volume;
 322
 323         /* fill in the superblock */
 324         sb->s_blocksize         = PAGE_CACHE_SIZE;
 325         sb->s_blocksize_bits    = PAGE_CACHE_SHIFT;
 326         sb->s_magic             = AFS_FS_MAGIC;
 327         sb->s_op                = &afs_super_ops;
 328         sb->s_fs_info           = as;
 329
 330         /* allocate the root inode and dentry */
 331         fid.vid         = as->volume->vid;
 332         fid.vnode       = 1;
 333         fid.unique      = 1;
 334         inode = afs_iget(sb, params->key, &fid, NULL, NULL);
 335         if (IS_ERR(inode))
 336                 goto error_inode;
 337
 338         ret = -ENOMEM;
 339         root = d_alloc_root(inode);
 340         if (!root)
 341                 goto error;
 342
 343         sb->s_root = root;
 344
 345         _leave(" = 0");
 346         return 0;
 347
 348 error_inode:
 349         ret = PTR_ERR(inode);
 350         inode = NULL;
 351 error:
 352         iput(inode);
 353         afs_put_volume(as->volume);
 354         kfree(as);
 355
 356         sb->s_fs_info = NULL;
 357
 358         _leave(" = %d", ret);
 359         return ret;
 360 }
 361
 362 /*
 363  * get an AFS superblock
 364  * - TODO: don't use get_sb_nodev(), but rather call sget() directly
 365  */
 366 static int afs_get_sb(struct file_system_type *fs_type,
 367                       int flags,
 368                       const char *dev_name,
 369                       void *options,
 370                       struct vfsmount *mnt)
 371 {
 372         struct afs_mount_params params;
 373         struct super_block *sb;
 374         struct afs_volume *vol;
 375         struct key *key;
 376         int ret;
 377
 378         _enter(",,%s,%p", dev_name, options);
 379
 380         memset(&params, 0, sizeof(params));
 381
 382         /* parse the options and device name */
 383         if (options) {
 384                 ret = afs_parse_options(&params, options, &dev_name);
 385                 if (ret < 0)
 386                         goto error;
 387         }
 388
 389
 390         ret = afs_parse_device_name(&params, dev_name);
 391         if (ret < 0)
 392                 goto error;
 393
 394         /* try and do the mount securely */
 395         key = afs_request_key(params.cell);
 396         if (IS_ERR(key)) {
 397                 _leave(" = %ld [key]", PTR_ERR(key));
 398                 ret = PTR_ERR(key);
 399                 goto error;
 400         }
 401         params.key = key;
 402
 403         /* parse the device name */
 404         vol = afs_volume_lookup(&params);
 405         if (IS_ERR(vol)) {
 406                 ret = PTR_ERR(vol);
 407                 goto error;
 408         }
 409         params.volume = vol;
 410
 411         /* allocate a deviceless superblock */
 412         sb = sget(fs_type, afs_test_super, set_anon_super, &params);
 413         if (IS_ERR(sb)) {
 414                 ret = PTR_ERR(sb);
 415                 goto error;
 416         }
 417
 418         if (!sb->s_root) {
 419                 /* initial superblock/root creation */
 420                 _debug("create");
 421                 sb->s_flags = flags;
 422                 ret = afs_fill_super(sb, &params);
 423                 if (ret < 0) {
 424                         up_write(&sb->s_umount);
 425                         deactivate_super(sb);
 426                         goto error;
 427                 }
 428                 sb->s_flags |= MS_ACTIVE;
 429         } else {
 430                 _debug("reuse");
 431                 ASSERTCMP(sb->s_flags, &, MS_ACTIVE);
 432         }
 433
 434         simple_set_mnt(mnt, sb);
 435         afs_put_volume(params.volume);
 436         afs_put_cell(params.cell);
 437         _leave(" = 0 [%p]", sb);
 438         return 0;
 439
 440 error:
 441         afs_put_volume(params.volume);
 442         afs_put_cell(params.cell);
 443         key_put(params.key);
 444         _leave(" = %d", ret);
 445         return ret;
 446 }
 447
 448 /*
 449  * finish the unmounting process on the superblock
 450  */
 451 static void afs_put_super(struct super_block *sb)
 452 {
 453         struct afs_super_info *as = sb->s_fs_info;
 454
 455         _enter("");
 456
 457         afs_put_volume(as->volume);
 458
 459         _leave("");
 460 }
 461
 462 /*
 463  * initialise an inode cache slab element prior to any use
 464  */
 465 static void afs_i_init_once(void *_vnode, struct kmem_cache *cachep,
 466                             unsigned long flags)
 467 {
 468         struct afs_vnode *vnode = _vnode;
 469
 470         if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) ==
 471             SLAB_CTOR_CONSTRUCTOR) {
 472                 memset(vnode, 0, sizeof(*vnode));
 473                 inode_init_once(&vnode->vfs_inode);
 474                 init_waitqueue_head(&vnode->update_waitq);
 475                 mutex_init(&vnode->permits_lock);
 476                 mutex_init(&vnode->validate_lock);
 477                 spin_lock_init(&vnode->lock);
 478                 INIT_WORK(&vnode->cb_broken_work, afs_broken_callback_work);
 479         }
 480 }
 481
 482 /*
 483  * allocate an AFS inode struct from our slab cache
 484  */
 485 static struct inode *afs_alloc_inode(struct super_block *sb)
 486 {
 487         struct afs_vnode *vnode;
 488
 489         vnode = kmem_cache_alloc(afs_inode_cachep, GFP_KERNEL);
 490         if (!vnode)
 491                 return NULL;
 492
 493         atomic_inc(&afs_count_active_inodes);
 494
 495         memset(&vnode->fid, 0, sizeof(vnode->fid));
 496         memset(&vnode->status, 0, sizeof(vnode->status));
 497
 498         vnode->volume           = NULL;
 499         vnode->update_cnt       = 0;
 500         vnode->flags            = 1 << AFS_VNODE_UNSET;
 501         vnode->cb_promised      = false;
 502
 503         return &vnode->vfs_inode;
 504 }
 505
 506 /*
 507  * destroy an AFS inode struct
 508  */
 509 static void afs_destroy_inode(struct inode *inode)
 510 {
 511         struct afs_vnode *vnode = AFS_FS_I(inode);
 512
 513         _enter("{%lu}", inode->i_ino);
 514
 515         _debug("DESTROY INODE %p", inode);
 516
 517         ASSERTCMP(vnode->server, ==, NULL);
 518
 519         kmem_cache_free(afs_inode_cachep, vnode);
 520         atomic_dec(&afs_count_active_inodes);
 521 }