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@infradead.org>
  14  *
  15  */
  16
  17 #include <linux/kernel.h>
  18 #include <linux/module.h>
  19 #include <linux/mount.h>
  20 #include <linux/init.h>
  21 #include <linux/slab.h>
  22 #include <linux/fs.h>
  23 #include <linux/pagemap.h>
  24 #include <linux/parser.h>
  25 #include <linux/statfs.h>
  26 #include <linux/sched.h>
  27 #include <linux/nsproxy.h>
  28 #include <net/net_namespace.h>
  29 #include "internal.h"
  30
  31 #define AFS_FS_MAGIC 0x6B414653 /* 'kAFS' */
  32
  33 static void afs_i_init_once(void *foo);
  34 static struct dentry *afs_mount(struct file_system_type *fs_type,
  35                       int flags, const char *dev_name, void *data);
  36 static void afs_kill_super(struct super_block *sb);
  37 static struct inode *afs_alloc_inode(struct super_block *sb);
  38 static void afs_destroy_inode(struct inode *inode);
  39 static int afs_statfs(struct dentry *dentry, struct kstatfs *buf);
  40
  41 struct file_system_type afs_fs_type = {
  42         .owner          = THIS_MODULE,
  43         .name           = "afs",
  44         .mount          = afs_mount,
  45         .kill_sb        = afs_kill_super,
  46         .fs_flags       = 0,
  47 };
  48
  49 static const struct super_operations afs_super_ops = {
  50         .statfs         = afs_statfs,
  51         .alloc_inode    = afs_alloc_inode,
  52         .drop_inode     = afs_drop_inode,
  53         .destroy_inode  = afs_destroy_inode,
  54         .evict_inode    = afs_evict_inode,
  55         .show_options   = generic_show_options,
  56 };
  57
  58 static struct kmem_cache *afs_inode_cachep;
  59 static atomic_t afs_count_active_inodes;
  60
  61 enum {
  62         afs_no_opt,
  63         afs_opt_cell,
  64         afs_opt_rwpath,
  65         afs_opt_vol,
  66         afs_opt_autocell,
  67 };
  68
  69 static const match_table_t afs_options_list = {
  70         { afs_opt_cell,         "cell=%s"       },
  71         { afs_opt_rwpath,       "rwpath"        },
  72         { afs_opt_vol,          "vol=%s"        },
  73         { afs_opt_autocell,     "autocell"      },
  74         { afs_no_opt,           NULL            },
  75 };
  76
  77 /*
  78  * initialise the filesystem
  79  */
  80 int __init afs_fs_init(void)
  81 {
  82         int ret;
  83
  84         _enter("");
  85
  86         /* create ourselves an inode cache */
  87         atomic_set(&afs_count_active_inodes, 0);
  88
  89         ret = -ENOMEM;
  90         afs_inode_cachep = kmem_cache_create("afs_inode_cache",
  91                                              sizeof(struct afs_vnode),
  92                                              0,
  93                                              SLAB_HWCACHE_ALIGN,
  94                                              afs_i_init_once);
  95         if (!afs_inode_cachep) {
  96                 printk(KERN_NOTICE "kAFS: Failed to allocate inode cache\n");
  97                 return ret;
  98         }
  99
 100         /* now export our filesystem to lesser mortals */
 101         ret = register_filesystem(&afs_fs_type);
 102         if (ret < 0) {
 103                 kmem_cache_destroy(afs_inode_cachep);
 104                 _leave(" = %d", ret);
 105                 return ret;
 106         }
 107
 108         _leave(" = 0");
 109         return 0;
 110 }
 111
 112 /*
 113  * clean up the filesystem
 114  */
 115 void __exit afs_fs_exit(void)
 116 {
 117         _enter("");
 118
 119         afs_mntpt_kill_timer();
 120         unregister_filesystem(&afs_fs_type);
 121
 122         if (atomic_read(&afs_count_active_inodes) != 0) {
 123                 printk("kAFS: %d active inode objects still present\n",
 124                        atomic_read(&afs_count_active_inodes));
 125                 BUG();
 126         }
 127
 128         /*
 129          * Make sure all delayed rcu free inodes are flushed before we
 130          * destroy cache.
 131          */
 132         rcu_barrier();
 133         kmem_cache_destroy(afs_inode_cachep);
 134         _leave("");
 135 }
 136
 137 /*
 138  * parse the mount options
 139  * - this function has been shamelessly adapted from the ext3 fs which
 140  *   shamelessly adapted it from the msdos fs
 141  */
 142 static int afs_parse_options(struct afs_mount_params *params,
 143                              char *options, const char **devname)
 144 {
 145         struct afs_cell *cell;
 146         substring_t args[MAX_OPT_ARGS];
 147         char *p;
 148         int token;
 149
 150         _enter("%s", options);
 151
 152         options[PAGE_SIZE - 1] = 0;
 153
 154         while ((p = strsep(&options, ","))) {
 155                 if (!*p)
 156                         continue;
 157
 158                 token = match_token(p, afs_options_list, args);
 159                 switch (token) {
 160                 case afs_opt_cell:
 161                         cell = afs_cell_lookup(args[0].from,
 162                                                args[0].to - args[0].from,
 163                                                false);
 164                         if (IS_ERR(cell))
 165                                 return PTR_ERR(cell);
 166                         afs_put_cell(params->cell);
 167                         params->cell = cell;
 168                         break;
 169
 170                 case afs_opt_rwpath:
 171                         params->rwpath = 1;
 172                         break;
 173
 174                 case afs_opt_vol:
 175                         *devname = args[0].from;
 176                         break;
 177
 178                 case afs_opt_autocell:
 179                         params->autocell = 1;
 180                         break;
 181
 182                 default:
 183                         printk(KERN_ERR "kAFS:"
 184                                " Unknown or invalid mount option: '%s'\n", p);
 185                         return -EINVAL;
 186                 }
 187         }
 188
 189         _leave(" = 0");
 190         return 0;
 191 }
 192
 193 /*
 194  * parse a device name to get cell name, volume name, volume type and R/W
 195  * selector
 196  * - this can be one of the following:
 197  *      "%[cell:]volume[.]"             R/W volume
 198  *      "#[cell:]volume[.]"             R/O or R/W volume (rwpath=0),
 199  *                                       or R/W (rwpath=1) volume
 200  *      "%[cell:]volume.readonly"       R/O volume
 201  *      "#[cell:]volume.readonly"       R/O volume
 202  *      "%[cell:]volume.backup"         Backup volume
 203  *      "#[cell:]volume.backup"         Backup volume
 204  */
 205 static int afs_parse_device_name(struct afs_mount_params *params,
 206                                  const char *name)
 207 {
 208         struct afs_cell *cell;
 209         const char *cellname, *suffix;
 210         int cellnamesz;
 211
 212         _enter(",%s", name);
 213
 214         if (!name) {
 215                 printk(KERN_ERR "kAFS: no volume name specified\n");
 216                 return -EINVAL;
 217         }
 218
 219         if ((name[0] != '%' && name[0] != '#') || !name[1]) {
 220                 printk(KERN_ERR "kAFS: unparsable volume name\n");
 221                 return -EINVAL;
 222         }
 223
 224         /* determine the type of volume we're looking for */
 225         params->type = AFSVL_ROVOL;
 226         params->force = false;
 227         if (params->rwpath || name[0] == '%') {
 228                 params->type = AFSVL_RWVOL;
 229                 params->force = true;
 230         }
 231         name++;
 232
 233         /* split the cell name out if there is one */
 234         params->volname = strchr(name, ':');
 235         if (params->volname) {
 236                 cellname = name;
 237                 cellnamesz = params->volname - name;
 238                 params->volname++;
 239         } else {
 240                 params->volname = name;
 241                 cellname = NULL;
 242                 cellnamesz = 0;
 243         }
 244
 245         /* the volume type is further affected by a possible suffix */
 246         suffix = strrchr(params->volname, '.');
 247         if (suffix) {
 248                 if (strcmp(suffix, ".readonly") == 0) {
 249                         params->type = AFSVL_ROVOL;
 250                         params->force = true;
 251                 } else if (strcmp(suffix, ".backup") == 0) {
 252                         params->type = AFSVL_BACKVOL;
 253                         params->force = true;
 254                 } else if (suffix[1] == 0) {
 255                 } else {
 256                         suffix = NULL;
 257                 }
 258         }
 259
 260         params->volnamesz = suffix ?
 261                 suffix - params->volname : strlen(params->volname);
 262
 263         _debug("cell %*.*s [%p]",
 264                cellnamesz, cellnamesz, cellname ?: "", params->cell);
 265
 266         /* lookup the cell record */
 267         if (cellname || !params->cell) {
 268                 cell = afs_cell_lookup(cellname, cellnamesz, true);
 269                 if (IS_ERR(cell)) {
 270                         printk(KERN_ERR "kAFS: unable to lookup cell '%*.*s'\n",
 271                                cellnamesz, cellnamesz, cellname ?: "");
 272                         return PTR_ERR(cell);
 273                 }
 274                 afs_put_cell(params->cell);
 275                 params->cell = cell;
 276         }
 277
 278         _debug("CELL:%s [%p] VOLUME:%*.*s SUFFIX:%s TYPE:%d%s",
 279                params->cell->name, params->cell,
 280                params->volnamesz, params->volnamesz, params->volname,
 281                suffix ?: "-", params->type, params->force ? " FORCE" : "");
 282
 283         return 0;
 284 }
 285
 286 /*
 287  * check a superblock to see if it's the one we're looking for
 288  */
 289 static int afs_test_super(struct super_block *sb, void *data)
 290 {
 291         struct afs_super_info *as1 = data;
 292         struct afs_super_info *as = sb->s_fs_info;
 293
 294         return as->volume == as1->volume;
 295 }
 296
 297 static int afs_set_super(struct super_block *sb, void *data)
 298 {
 299         sb->s_fs_info = data;
 300         return set_anon_super(sb, NULL);
 301 }
 302
 303 /*
 304  * fill in the superblock
 305  */
 306 static int afs_fill_super(struct super_block *sb,
 307                           struct afs_mount_params *params)
 308 {
 309         struct afs_super_info *as = sb->s_fs_info;
 310         struct afs_fid fid;
 311         struct inode *inode = NULL;
 312         int ret;
 313
 314         _enter("");
 315
 316         /* fill in the superblock */
 317         sb->s_blocksize         = PAGE_CACHE_SIZE;
 318         sb->s_blocksize_bits    = PAGE_CACHE_SHIFT;
 319         sb->s_magic             = AFS_FS_MAGIC;
 320         sb->s_op                = &afs_super_ops;
 321         sb->s_bdi               = &as->volume->bdi;
 322         strlcpy(sb->s_id, as->volume->vlocation->vldb.name, sizeof(sb->s_id));
 323
 324         /* allocate the root inode and dentry */
 325         fid.vid         = as->volume->vid;
 326         fid.vnode       = 1;
 327         fid.unique      = 1;
 328         inode = afs_iget(sb, params->key, &fid, NULL, NULL);
 329         if (IS_ERR(inode))
 330                 return PTR_ERR(inode);
 331
 332         if (params->autocell)
 333                 set_bit(AFS_VNODE_AUTOCELL, &AFS_FS_I(inode)->flags);
 334
 335         ret = -ENOMEM;
 336         sb->s_root = d_make_root(inode);
 337         if (!sb->s_root)
 338                 goto error;
 339
 340         sb->s_d_op = &afs_fs_dentry_operations;
 341
 342         _leave(" = 0");
 343         return 0;
 344
 345 error:
 346         _leave(" = %d", ret);
 347         return ret;
 348 }
 349
 350 /*
 351  * get an AFS superblock
 352  */
 353 static struct dentry *afs_mount(struct file_system_type *fs_type,
 354                       int flags, const char *dev_name, void *options)
 355 {
 356         struct afs_mount_params params;
 357         struct super_block *sb;
 358         struct afs_volume *vol;
 359         struct key *key;
 360         char *new_opts = kstrdup(options, GFP_KERNEL);
 361         struct afs_super_info *as;
 362         int ret;
 363
 364         _enter(",,%s,%p", dev_name, options);
 365
 366         memset(&params, 0, sizeof(params));
 367
 368         ret = -EINVAL;
 369         if (current->nsproxy->net_ns != &init_net)
 370                 goto error;
 371
 372         /* parse the options and device name */
 373         if (options) {
 374                 ret = afs_parse_options(&params, options, &dev_name);
 375                 if (ret < 0)
 376                         goto error;
 377         }
 378
 379         ret = afs_parse_device_name(&params, dev_name);
 380         if (ret < 0)
 381                 goto error;
 382
 383         /* try and do the mount securely */
 384         key = afs_request_key(params.cell);
 385         if (IS_ERR(key)) {
 386                 _leave(" = %ld [key]", PTR_ERR(key));
 387                 ret = PTR_ERR(key);
 388                 goto error;
 389         }
 390         params.key = key;
 391
 392         /* parse the device name */
 393         vol = afs_volume_lookup(&params);
 394         if (IS_ERR(vol)) {
 395                 ret = PTR_ERR(vol);
 396                 goto error;
 397         }
 398
 399         /* allocate a superblock info record */
 400         as = kzalloc(sizeof(struct afs_super_info), GFP_KERNEL);
 401         if (!as) {
 402                 ret = -ENOMEM;
 403                 afs_put_volume(vol);
 404                 goto error;
 405         }
 406         as->volume = vol;
 407
 408         /* allocate a deviceless superblock */
 409         sb = sget(fs_type, afs_test_super, afs_set_super, flags, as);
 410         if (IS_ERR(sb)) {
 411                 ret = PTR_ERR(sb);
 412                 afs_put_volume(vol);
 413                 kfree(as);
 414                 goto error;
 415         }
 416
 417         if (!sb->s_root) {
 418                 /* initial superblock/root creation */
 419                 _debug("create");
 420                 ret = afs_fill_super(sb, &params);
 421                 if (ret < 0) {
 422                         deactivate_locked_super(sb);
 423                         goto error;
 424                 }
 425                 save_mount_options(sb, new_opts);
 426                 sb->s_flags |= MS_ACTIVE;
 427         } else {
 428                 _debug("reuse");
 429                 ASSERTCMP(sb->s_flags, &, MS_ACTIVE);
 430                 afs_put_volume(vol);
 431                 kfree(as);
 432         }
 433
 434         afs_put_cell(params.cell);
 435         kfree(new_opts);
 436         _leave(" = 0 [%p]", sb);
 437         return dget(sb->s_root);
 438
 439 error:
 440         afs_put_cell(params.cell);
 441         key_put(params.key);
 442         kfree(new_opts);
 443         _leave(" = %d", ret);
 444         return ERR_PTR(ret);
 445 }
 446
 447 static void afs_kill_super(struct super_block *sb)
 448 {
 449         struct afs_super_info *as = sb->s_fs_info;
 450         kill_anon_super(sb);
 451         afs_put_volume(as->volume);
 452         kfree(as);
 453 }
 454
 455 /*
 456  * initialise an inode cache slab element prior to any use
 457  */
 458 static void afs_i_init_once(void *_vnode)
 459 {
 460         struct afs_vnode *vnode = _vnode;
 461
 462         memset(vnode, 0, sizeof(*vnode));
 463         inode_init_once(&vnode->vfs_inode);
 464         init_waitqueue_head(&vnode->update_waitq);
 465         mutex_init(&vnode->permits_lock);
 466         mutex_init(&vnode->validate_lock);
 467         spin_lock_init(&vnode->writeback_lock);
 468         spin_lock_init(&vnode->lock);
 469         INIT_LIST_HEAD(&vnode->writebacks);
 470         INIT_LIST_HEAD(&vnode->pending_locks);
 471         INIT_LIST_HEAD(&vnode->granted_locks);
 472         INIT_DELAYED_WORK(&vnode->lock_work, afs_lock_work);
 473         INIT_WORK(&vnode->cb_broken_work, afs_broken_callback_work);
 474 }
 475
 476 /*
 477  * allocate an AFS inode struct from our slab cache
 478  */
 479 static struct inode *afs_alloc_inode(struct super_block *sb)
 480 {
 481         struct afs_vnode *vnode;
 482
 483         vnode = kmem_cache_alloc(afs_inode_cachep, GFP_KERNEL);
 484         if (!vnode)
 485                 return NULL;
 486
 487         atomic_inc(&afs_count_active_inodes);
 488
 489         memset(&vnode->fid, 0, sizeof(vnode->fid));
 490         memset(&vnode->status, 0, sizeof(vnode->status));
 491
 492         vnode->volume           = NULL;
 493         vnode->update_cnt       = 0;
 494         vnode->flags            = 1 << AFS_VNODE_UNSET;
 495         vnode->cb_promised      = false;
 496
 497         _leave(" = %p", &vnode->vfs_inode);
 498         return &vnode->vfs_inode;
 499 }
 500
 501 static void afs_i_callback(struct rcu_head *head)
 502 {
 503         struct inode *inode = container_of(head, struct inode, i_rcu);
 504         struct afs_vnode *vnode = AFS_FS_I(inode);
 505         kmem_cache_free(afs_inode_cachep, vnode);
 506 }
 507
 508 /*
 509  * destroy an AFS inode struct
 510  */
 511 static void afs_destroy_inode(struct inode *inode)
 512 {
 513         struct afs_vnode *vnode = AFS_FS_I(inode);
 514
 515         _enter("%p{%x:%u}", inode, vnode->fid.vid, vnode->fid.vnode);
 516
 517         _debug("DESTROY INODE %p", inode);
 518
 519         ASSERTCMP(vnode->server, ==, NULL);
 520
 521         call_rcu(&inode->i_rcu, afs_i_callback);
 522         atomic_dec(&afs_count_active_inodes);
 523 }
 524
 525 /*
 526  * return information about an AFS volume
 527  */
 528 static int afs_statfs(struct dentry *dentry, struct kstatfs *buf)
 529 {
 530         struct afs_volume_status vs;
 531         struct afs_vnode *vnode = AFS_FS_I(dentry->d_inode);
 532         struct key *key;
 533         int ret;
 534
 535         key = afs_request_key(vnode->volume->cell);
 536         if (IS_ERR(key))
 537                 return PTR_ERR(key);
 538
 539         ret = afs_vnode_get_volume_status(vnode, key, &vs);
 540         key_put(key);
 541         if (ret < 0) {
 542                 _leave(" = %d", ret);
 543                 return ret;
 544         }
 545
 546         buf->f_type     = dentry->d_sb->s_magic;
 547         buf->f_bsize    = AFS_BLOCK_SIZE;
 548         buf->f_namelen  = AFSNAMEMAX - 1;
 549
 550         if (vs.max_quota == 0)
 551                 buf->f_blocks = vs.part_max_blocks;
 552         else
 553                 buf->f_blocks = vs.max_quota;
 554         buf->f_bavail = buf->f_bfree = buf->f_blocks - vs.blocks_in_use;
 555         return 0;
 556 }