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 static int afs_show_devname(struct seq_file *m, struct dentry *root);
  41 static int afs_show_options(struct seq_file *m, struct dentry *root);
  42
  43 struct file_system_type afs_fs_type = {
  44         .owner          = THIS_MODULE,
  45         .name           = "afs",
  46         .mount          = afs_mount,
  47         .kill_sb        = afs_kill_super,
  48         .fs_flags       = 0,
  49 };
  50 MODULE_ALIAS_FS("afs");
  51
  52 static const struct super_operations afs_super_ops = {
  53         .statfs         = afs_statfs,
  54         .alloc_inode    = afs_alloc_inode,
  55         .drop_inode     = afs_drop_inode,
  56         .destroy_inode  = afs_destroy_inode,
  57         .evict_inode    = afs_evict_inode,
  58         .show_devname   = afs_show_devname,
  59         .show_options   = afs_show_options,
  60 };
  61
  62 static struct kmem_cache *afs_inode_cachep;
  63 static atomic_t afs_count_active_inodes;
  64
  65 enum {
  66         afs_no_opt,
  67         afs_opt_cell,
  68         afs_opt_rwpath,
  69         afs_opt_vol,
  70         afs_opt_autocell,
  71 };
  72
  73 static const match_table_t afs_options_list = {
  74         { afs_opt_cell,         "cell=%s"       },
  75         { afs_opt_rwpath,       "rwpath"        },
  76         { afs_opt_vol,          "vol=%s"        },
  77         { afs_opt_autocell,     "autocell"      },
  78         { afs_no_opt,           NULL            },
  79 };
  80
  81 /*
  82  * initialise the filesystem
  83  */
  84 int __init afs_fs_init(void)
  85 {
  86         int ret;
  87
  88         _enter("");
  89
  90         /* create ourselves an inode cache */
  91         atomic_set(&afs_count_active_inodes, 0);
  92
  93         ret = -ENOMEM;
  94         afs_inode_cachep = kmem_cache_create("afs_inode_cache",
  95                                              sizeof(struct afs_vnode),
  96                                              0,
  97                                              SLAB_HWCACHE_ALIGN|SLAB_ACCOUNT,
  98                                              afs_i_init_once);
  99         if (!afs_inode_cachep) {
 100                 printk(KERN_NOTICE "kAFS: Failed to allocate inode cache\n");
 101                 return ret;
 102         }
 103
 104         /* now export our filesystem to lesser mortals */
 105         ret = register_filesystem(&afs_fs_type);
 106         if (ret < 0) {
 107                 kmem_cache_destroy(afs_inode_cachep);
 108                 _leave(" = %d", ret);
 109                 return ret;
 110         }
 111
 112         _leave(" = 0");
 113         return 0;
 114 }
 115
 116 /*
 117  * clean up the filesystem
 118  */
 119 void __exit afs_fs_exit(void)
 120 {
 121         _enter("");
 122
 123         afs_mntpt_kill_timer();
 124         unregister_filesystem(&afs_fs_type);
 125
 126         if (atomic_read(&afs_count_active_inodes) != 0) {
 127                 printk("kAFS: %d active inode objects still present\n",
 128                        atomic_read(&afs_count_active_inodes));
 129                 BUG();
 130         }
 131
 132         /*
 133          * Make sure all delayed rcu free inodes are flushed before we
 134          * destroy cache.
 135          */
 136         rcu_barrier();
 137         kmem_cache_destroy(afs_inode_cachep);
 138         _leave("");
 139 }
 140
 141 /*
 142  * Display the mount device name in /proc/mounts.
 143  */
 144 static int afs_show_devname(struct seq_file *m, struct dentry *root)
 145 {
 146         struct afs_super_info *as = root->d_sb->s_fs_info;
 147         struct afs_volume *volume = as->volume;
 148         struct afs_cell *cell = volume->cell;
 149         const char *suf = "";
 150         char pref = '%';
 151
 152         switch (volume->type) {
 153         case AFSVL_RWVOL:
 154                 break;
 155         case AFSVL_ROVOL:
 156                 pref = '#';
 157                 if (volume->type_force)
 158                         suf = ".readonly";
 159                 break;
 160         case AFSVL_BACKVOL:
 161                 pref = '#';
 162                 suf = ".backup";
 163                 break;
 164         }
 165
 166         seq_printf(m, "%c%s:%s%s", pref, cell->name, volume->vlocation->vldb.name, suf);
 167         return 0;
 168 }
 169
 170 /*
 171  * Display the mount options in /proc/mounts.
 172  */
 173 static int afs_show_options(struct seq_file *m, struct dentry *root)
 174 {
 175         if (test_bit(AFS_VNODE_AUTOCELL, &AFS_FS_I(d_inode(root))->flags))
 176                 seq_puts(m, "autocell");
 177         return 0;
 178 }
 179
 180 /*
 181  * parse the mount options
 182  * - this function has been shamelessly adapted from the ext3 fs which
 183  *   shamelessly adapted it from the msdos fs
 184  */
 185 static int afs_parse_options(struct afs_mount_params *params,
 186                              char *options, const char **devname)
 187 {
 188         struct afs_cell *cell;
 189         substring_t args[MAX_OPT_ARGS];
 190         char *p;
 191         int token;
 192
 193         _enter("%s", options);
 194
 195         options[PAGE_SIZE - 1] = 0;
 196
 197         while ((p = strsep(&options, ","))) {
 198                 if (!*p)
 199                         continue;
 200
 201                 token = match_token(p, afs_options_list, args);
 202                 switch (token) {
 203                 case afs_opt_cell:
 204                         cell = afs_cell_lookup(args[0].from,
 205                                                args[0].to - args[0].from,
 206                                                false);
 207                         if (IS_ERR(cell))
 208                                 return PTR_ERR(cell);
 209                         afs_put_cell(params->cell);
 210                         params->cell = cell;
 211                         break;
 212
 213                 case afs_opt_rwpath:
 214                         params->rwpath = 1;
 215                         break;
 216
 217                 case afs_opt_vol:
 218                         *devname = args[0].from;
 219                         break;
 220
 221                 case afs_opt_autocell:
 222                         params->autocell = 1;
 223                         break;
 224
 225                 default:
 226                         printk(KERN_ERR "kAFS:"
 227                                " Unknown or invalid mount option: '%s'\n", p);
 228                         return -EINVAL;
 229                 }
 230         }
 231
 232         _leave(" = 0");
 233         return 0;
 234 }
 235
 236 /*
 237  * parse a device name to get cell name, volume name, volume type and R/W
 238  * selector
 239  * - this can be one of the following:
 240  *      "%[cell:]volume[.]"             R/W volume
 241  *      "#[cell:]volume[.]"             R/O or R/W volume (rwpath=0),
 242  *                                       or R/W (rwpath=1) volume
 243  *      "%[cell:]volume.readonly"       R/O volume
 244  *      "#[cell:]volume.readonly"       R/O volume
 245  *      "%[cell:]volume.backup"         Backup volume
 246  *      "#[cell:]volume.backup"         Backup volume
 247  */
 248 static int afs_parse_device_name(struct afs_mount_params *params,
 249                                  const char *name)
 250 {
 251         struct afs_cell *cell;
 252         const char *cellname, *suffix;
 253         int cellnamesz;
 254
 255         _enter(",%s", name);
 256
 257         if (!name) {
 258                 printk(KERN_ERR "kAFS: no volume name specified\n");
 259                 return -EINVAL;
 260         }
 261
 262         if ((name[0] != '%' && name[0] != '#') || !name[1]) {
 263                 printk(KERN_ERR "kAFS: unparsable volume name\n");
 264                 return -EINVAL;
 265         }
 266
 267         /* determine the type of volume we're looking for */
 268         params->type = AFSVL_ROVOL;
 269         params->force = false;
 270         if (params->rwpath || name[0] == '%') {
 271                 params->type = AFSVL_RWVOL;
 272                 params->force = true;
 273         }
 274         name++;
 275
 276         /* split the cell name out if there is one */
 277         params->volname = strchr(name, ':');
 278         if (params->volname) {
 279                 cellname = name;
 280                 cellnamesz = params->volname - name;
 281                 params->volname++;
 282         } else {
 283                 params->volname = name;
 284                 cellname = NULL;
 285                 cellnamesz = 0;
 286         }
 287
 288         /* the volume type is further affected by a possible suffix */
 289         suffix = strrchr(params->volname, '.');
 290         if (suffix) {
 291                 if (strcmp(suffix, ".readonly") == 0) {
 292                         params->type = AFSVL_ROVOL;
 293                         params->force = true;
 294                 } else if (strcmp(suffix, ".backup") == 0) {
 295                         params->type = AFSVL_BACKVOL;
 296                         params->force = true;
 297                 } else if (suffix[1] == 0) {
 298                 } else {
 299                         suffix = NULL;
 300                 }
 301         }
 302
 303         params->volnamesz = suffix ?
 304                 suffix - params->volname : strlen(params->volname);
 305
 306         _debug("cell %*.*s [%p]",
 307                cellnamesz, cellnamesz, cellname ?: "", params->cell);
 308
 309         /* lookup the cell record */
 310         if (cellname || !params->cell) {
 311                 cell = afs_cell_lookup(cellname, cellnamesz, true);
 312                 if (IS_ERR(cell)) {
 313                         printk(KERN_ERR "kAFS: unable to lookup cell '%*.*s'\n",
 314                                cellnamesz, cellnamesz, cellname ?: "");
 315                         return PTR_ERR(cell);
 316                 }
 317                 afs_put_cell(params->cell);
 318                 params->cell = cell;
 319         }
 320
 321         _debug("CELL:%s [%p] VOLUME:%*.*s SUFFIX:%s TYPE:%d%s",
 322                params->cell->name, params->cell,
 323                params->volnamesz, params->volnamesz, params->volname,
 324                suffix ?: "-", params->type, params->force ? " FORCE" : "");
 325
 326         return 0;
 327 }
 328
 329 /*
 330  * check a superblock to see if it's the one we're looking for
 331  */
 332 static int afs_test_super(struct super_block *sb, void *data)
 333 {
 334         struct afs_super_info *as1 = data;
 335         struct afs_super_info *as = sb->s_fs_info;
 336
 337         return as->volume == as1->volume;
 338 }
 339
 340 static int afs_set_super(struct super_block *sb, void *data)
 341 {
 342         sb->s_fs_info = data;
 343         return set_anon_super(sb, NULL);
 344 }
 345
 346 /*
 347  * fill in the superblock
 348  */
 349 static int afs_fill_super(struct super_block *sb,
 350                           struct afs_mount_params *params)
 351 {
 352         struct afs_super_info *as = sb->s_fs_info;
 353         struct afs_fid fid;
 354         struct inode *inode = NULL;
 355         int ret;
 356
 357         _enter("");
 358
 359         /* fill in the superblock */
 360         sb->s_blocksize         = PAGE_SIZE;
 361         sb->s_blocksize_bits    = PAGE_SHIFT;
 362         sb->s_magic             = AFS_FS_MAGIC;
 363         sb->s_op                = &afs_super_ops;
 364         sb->s_xattr             = afs_xattr_handlers;
 365         ret = super_setup_bdi(sb);
 366         if (ret)
 367                 return ret;
 368         sb->s_bdi->ra_pages     = VM_MAX_READAHEAD * 1024 / PAGE_SIZE;
 369         strlcpy(sb->s_id, as->volume->vlocation->vldb.name, sizeof(sb->s_id));
 370
 371         /* allocate the root inode and dentry */
 372         fid.vid         = as->volume->vid;
 373         fid.vnode       = 1;
 374         fid.unique      = 1;
 375         inode = afs_iget(sb, params->key, &fid, NULL, NULL);
 376         if (IS_ERR(inode))
 377                 return PTR_ERR(inode);
 378
 379         if (params->autocell)
 380                 set_bit(AFS_VNODE_AUTOCELL, &AFS_FS_I(inode)->flags);
 381
 382         ret = -ENOMEM;
 383         sb->s_root = d_make_root(inode);
 384         if (!sb->s_root)
 385                 goto error;
 386
 387         sb->s_d_op = &afs_fs_dentry_operations;
 388
 389         _leave(" = 0");
 390         return 0;
 391
 392 error:
 393         _leave(" = %d", ret);
 394         return ret;
 395 }
 396
 397 /*
 398  * get an AFS superblock
 399  */
 400 static struct dentry *afs_mount(struct file_system_type *fs_type,
 401                       int flags, const char *dev_name, void *options)
 402 {
 403         struct afs_mount_params params;
 404         struct super_block *sb;
 405         struct afs_volume *vol;
 406         struct key *key;
 407         char *new_opts = kstrdup(options, GFP_KERNEL);
 408         struct afs_super_info *as;
 409         int ret;
 410
 411         _enter(",,%s,%p", dev_name, options);
 412
 413         memset(&params, 0, sizeof(params));
 414
 415         ret = -EINVAL;
 416         if (current->nsproxy->net_ns != &init_net)
 417                 goto error;
 418
 419         /* parse the options and device name */
 420         if (options) {
 421                 ret = afs_parse_options(&params, options, &dev_name);
 422                 if (ret < 0)
 423                         goto error;
 424         }
 425
 426         ret = afs_parse_device_name(&params, dev_name);
 427         if (ret < 0)
 428                 goto error;
 429
 430         /* try and do the mount securely */
 431         key = afs_request_key(params.cell);
 432         if (IS_ERR(key)) {
 433                 _leave(" = %ld [key]", PTR_ERR(key));
 434                 ret = PTR_ERR(key);
 435                 goto error;
 436         }
 437         params.key = key;
 438
 439         /* parse the device name */
 440         vol = afs_volume_lookup(&params);
 441         if (IS_ERR(vol)) {
 442                 ret = PTR_ERR(vol);
 443                 goto error;
 444         }
 445
 446         /* allocate a superblock info record */
 447         as = kzalloc(sizeof(struct afs_super_info), GFP_KERNEL);
 448         if (!as) {
 449                 ret = -ENOMEM;
 450                 afs_put_volume(vol);
 451                 goto error;
 452         }
 453         as->volume = vol;
 454
 455         /* allocate a deviceless superblock */
 456         sb = sget(fs_type, afs_test_super, afs_set_super, flags, as);
 457         if (IS_ERR(sb)) {
 458                 ret = PTR_ERR(sb);
 459                 afs_put_volume(vol);
 460                 kfree(as);
 461                 goto error;
 462         }
 463
 464         if (!sb->s_root) {
 465                 /* initial superblock/root creation */
 466                 _debug("create");
 467                 ret = afs_fill_super(sb, &params);
 468                 if (ret < 0) {
 469                         deactivate_locked_super(sb);
 470                         goto error;
 471                 }
 472                 sb->s_flags |= MS_ACTIVE;
 473         } else {
 474                 _debug("reuse");
 475                 ASSERTCMP(sb->s_flags, &, MS_ACTIVE);
 476                 afs_put_volume(vol);
 477                 kfree(as);
 478         }
 479
 480         afs_put_cell(params.cell);
 481         kfree(new_opts);
 482         _leave(" = 0 [%p]", sb);
 483         return dget(sb->s_root);
 484
 485 error:
 486         afs_put_cell(params.cell);
 487         key_put(params.key);
 488         kfree(new_opts);
 489         _leave(" = %d", ret);
 490         return ERR_PTR(ret);
 491 }
 492
 493 static void afs_kill_super(struct super_block *sb)
 494 {
 495         struct afs_super_info *as = sb->s_fs_info;
 496         kill_anon_super(sb);
 497         afs_put_volume(as->volume);
 498         kfree(as);
 499 }
 500
 501 /*
 502  * initialise an inode cache slab element prior to any use
 503  */
 504 static void afs_i_init_once(void *_vnode)
 505 {
 506         struct afs_vnode *vnode = _vnode;
 507
 508         memset(vnode, 0, sizeof(*vnode));
 509         inode_init_once(&vnode->vfs_inode);
 510         init_waitqueue_head(&vnode->update_waitq);
 511         mutex_init(&vnode->permits_lock);
 512         mutex_init(&vnode->validate_lock);
 513         spin_lock_init(&vnode->writeback_lock);
 514         spin_lock_init(&vnode->lock);
 515         INIT_LIST_HEAD(&vnode->writebacks);
 516         INIT_LIST_HEAD(&vnode->pending_locks);
 517         INIT_LIST_HEAD(&vnode->granted_locks);
 518         INIT_DELAYED_WORK(&vnode->lock_work, afs_lock_work);
 519         INIT_WORK(&vnode->cb_broken_work, afs_broken_callback_work);
 520 }
 521
 522 /*
 523  * allocate an AFS inode struct from our slab cache
 524  */
 525 static struct inode *afs_alloc_inode(struct super_block *sb)
 526 {
 527         struct afs_vnode *vnode;
 528
 529         vnode = kmem_cache_alloc(afs_inode_cachep, GFP_KERNEL);
 530         if (!vnode)
 531                 return NULL;
 532
 533         atomic_inc(&afs_count_active_inodes);
 534
 535         memset(&vnode->fid, 0, sizeof(vnode->fid));
 536         memset(&vnode->status, 0, sizeof(vnode->status));
 537
 538         vnode->volume           = NULL;
 539         vnode->update_cnt       = 0;
 540         vnode->flags            = 1 << AFS_VNODE_UNSET;
 541         vnode->cb_promised      = false;
 542
 543         _leave(" = %p", &vnode->vfs_inode);
 544         return &vnode->vfs_inode;
 545 }
 546
 547 static void afs_i_callback(struct rcu_head *head)
 548 {
 549         struct inode *inode = container_of(head, struct inode, i_rcu);
 550         struct afs_vnode *vnode = AFS_FS_I(inode);
 551         kmem_cache_free(afs_inode_cachep, vnode);
 552 }
 553
 554 /*
 555  * destroy an AFS inode struct
 556  */
 557 static void afs_destroy_inode(struct inode *inode)
 558 {
 559         struct afs_vnode *vnode = AFS_FS_I(inode);
 560
 561         _enter("%p{%x:%u}", inode, vnode->fid.vid, vnode->fid.vnode);
 562
 563         _debug("DESTROY INODE %p", inode);
 564
 565         ASSERTCMP(vnode->server, ==, NULL);
 566
 567         call_rcu(&inode->i_rcu, afs_i_callback);
 568         atomic_dec(&afs_count_active_inodes);
 569 }
 570
 571 /*
 572  * return information about an AFS volume
 573  */
 574 static int afs_statfs(struct dentry *dentry, struct kstatfs *buf)
 575 {
 576         struct afs_volume_status vs;
 577         struct afs_vnode *vnode = AFS_FS_I(d_inode(dentry));
 578         struct key *key;
 579         int ret;
 580
 581         key = afs_request_key(vnode->volume->cell);
 582         if (IS_ERR(key))
 583                 return PTR_ERR(key);
 584
 585         ret = afs_vnode_get_volume_status(vnode, key, &vs);
 586         key_put(key);
 587         if (ret < 0) {
 588                 _leave(" = %d", ret);
 589                 return ret;
 590         }
 591
 592         buf->f_type     = dentry->d_sb->s_magic;
 593         buf->f_bsize    = AFS_BLOCK_SIZE;
 594         buf->f_namelen  = AFSNAMEMAX - 1;
 595
 596         if (vs.max_quota == 0)
 597                 buf->f_blocks = vs.part_max_blocks;
 598         else
 599                 buf->f_blocks = vs.max_quota;
 600         buf->f_bavail = buf->f_bfree = buf->f_blocks - vs.blocks_in_use;
 601         return 0;
 602 }