fs/afs/super.c

   1 /* AFS superblock handling
   2  *
   3  * Copyright (c) 2002, 2007, 2018 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/fs_parser.h>
  25 #include <linux/statfs.h>
  26 #include <linux/sched.h>
  27 #include <linux/nsproxy.h>
  28 #include <linux/magic.h>
  29 #include <net/net_namespace.h>
  30 #include "internal.h"
  31
  32 static void afs_i_init_once(void *foo);
  33 static void afs_kill_super(struct super_block *sb);
  34 static struct inode *afs_alloc_inode(struct super_block *sb);
  35 static void afs_destroy_inode(struct inode *inode);
  36 static int afs_statfs(struct dentry *dentry, struct kstatfs *buf);
  37 static int afs_show_devname(struct seq_file *m, struct dentry *root);
  38 static int afs_show_options(struct seq_file *m, struct dentry *root);
  39 static int afs_init_fs_context(struct fs_context *fc);
  40 static const struct fs_parameter_description afs_fs_parameters;
  41
  42 struct file_system_type afs_fs_type = {
  43         .owner                  = THIS_MODULE,
  44         .name                   = "afs",
  45         .init_fs_context        = afs_init_fs_context,
  46         .parameters             = &afs_fs_parameters,
  47         .kill_sb                = afs_kill_super,
  48         .fs_flags               = 0,
  49 };
  50 MODULE_ALIAS_FS("afs");
  51
  52 int afs_net_id;
  53
  54 static const struct super_operations afs_super_ops = {
  55         .statfs         = afs_statfs,
  56         .alloc_inode    = afs_alloc_inode,
  57         .drop_inode     = afs_drop_inode,
  58         .destroy_inode  = afs_destroy_inode,
  59         .evict_inode    = afs_evict_inode,
  60         .show_devname   = afs_show_devname,
  61         .show_options   = afs_show_options,
  62 };
  63
  64 static struct kmem_cache *afs_inode_cachep;
  65 static atomic_t afs_count_active_inodes;
  66
  67 enum afs_param {
  68         Opt_autocell,
  69         Opt_dyn,
  70         Opt_source,
  71 };
  72
  73 static const struct fs_parameter_spec afs_param_specs[] = {
  74         fsparam_flag  ("autocell",      Opt_autocell),
  75         fsparam_flag  ("dyn",           Opt_dyn),
  76         fsparam_string("source",        Opt_source),
  77         {}
  78 };
  79
  80 static const struct fs_parameter_description afs_fs_parameters = {
  81         .name           = "kAFS",
  82         .specs          = afs_param_specs,
  83 };
  84
  85 /*
  86  * initialise the filesystem
  87  */
  88 int __init afs_fs_init(void)
  89 {
  90         int ret;
  91
  92         _enter("");
  93
  94         /* create ourselves an inode cache */
  95         atomic_set(&afs_count_active_inodes, 0);
  96
  97         ret = -ENOMEM;
  98         afs_inode_cachep = kmem_cache_create("afs_inode_cache",
  99                                              sizeof(struct afs_vnode),
 100                                              0,
 101                                              SLAB_HWCACHE_ALIGN|SLAB_ACCOUNT,
 102                                              afs_i_init_once);
 103         if (!afs_inode_cachep) {
 104                 printk(KERN_NOTICE "kAFS: Failed to allocate inode cache\n");
 105                 return ret;
 106         }
 107
 108         /* now export our filesystem to lesser mortals */
 109         ret = register_filesystem(&afs_fs_type);
 110         if (ret < 0) {
 111                 kmem_cache_destroy(afs_inode_cachep);
 112                 _leave(" = %d", ret);
 113                 return ret;
 114         }
 115
 116         _leave(" = 0");
 117         return 0;
 118 }
 119
 120 /*
 121  * clean up the filesystem
 122  */
 123 void afs_fs_exit(void)
 124 {
 125         _enter("");
 126
 127         afs_mntpt_kill_timer();
 128         unregister_filesystem(&afs_fs_type);
 129
 130         if (atomic_read(&afs_count_active_inodes) != 0) {
 131                 printk("kAFS: %d active inode objects still present\n",
 132                        atomic_read(&afs_count_active_inodes));
 133                 BUG();
 134         }
 135
 136         /*
 137          * Make sure all delayed rcu free inodes are flushed before we
 138          * destroy cache.
 139          */
 140         rcu_barrier();
 141         kmem_cache_destroy(afs_inode_cachep);
 142         _leave("");
 143 }
 144
 145 /*
 146  * Display the mount device name in /proc/mounts.
 147  */
 148 static int afs_show_devname(struct seq_file *m, struct dentry *root)
 149 {
 150         struct afs_super_info *as = AFS_FS_S(root->d_sb);
 151         struct afs_volume *volume = as->volume;
 152         struct afs_cell *cell = as->cell;
 153         const char *suf = "";
 154         char pref = '%';
 155
 156         if (as->dyn_root) {
 157                 seq_puts(m, "none");
 158                 return 0;
 159         }
 160
 161         switch (volume->type) {
 162         case AFSVL_RWVOL:
 163                 break;
 164         case AFSVL_ROVOL:
 165                 pref = '#';
 166                 if (volume->type_force)
 167                         suf = ".readonly";
 168                 break;
 169         case AFSVL_BACKVOL:
 170                 pref = '#';
 171                 suf = ".backup";
 172                 break;
 173         }
 174
 175         seq_printf(m, "%c%s:%s%s", pref, cell->name, volume->name, suf);
 176         return 0;
 177 }
 178
 179 /*
 180  * Display the mount options in /proc/mounts.
 181  */
 182 static int afs_show_options(struct seq_file *m, struct dentry *root)
 183 {
 184         struct afs_super_info *as = AFS_FS_S(root->d_sb);
 185
 186         if (as->dyn_root)
 187                 seq_puts(m, ",dyn");
 188         if (test_bit(AFS_VNODE_AUTOCELL, &AFS_FS_I(d_inode(root))->flags))
 189                 seq_puts(m, ",autocell");
 190         return 0;
 191 }
 192
 193 /*
 194  * Parse the source name to get cell name, volume name, volume type and R/W
 195  * selector.
 196  *
 197  * This can be one of the following:
 198  *      "%[cell:]volume[.]"             R/W volume
 199  *      "#[cell:]volume[.]"             R/O or R/W volume (R/O parent),
 200  *                                       or R/W (R/W parent) volume
 201  *      "%[cell:]volume.readonly"       R/O volume
 202  *      "#[cell:]volume.readonly"       R/O volume
 203  *      "%[cell:]volume.backup"         Backup volume
 204  *      "#[cell:]volume.backup"         Backup volume
 205  */
 206 static int afs_parse_source(struct fs_context *fc, struct fs_parameter *param)
 207 {
 208         struct afs_fs_context *ctx = fc->fs_private;
 209         struct afs_cell *cell;
 210         const char *cellname, *suffix, *name = param->string;
 211         int cellnamesz;
 212
 213         _enter(",%s", name);
 214
 215         if (!name) {
 216                 printk(KERN_ERR "kAFS: no volume name specified\n");
 217                 return -EINVAL;
 218         }
 219
 220         if ((name[0] != '%' && name[0] != '#') || !name[1]) {
 221                 /* To use dynroot, we don't want to have to provide a source */
 222                 if (strcmp(name, "none") == 0) {
 223                         ctx->no_cell = true;
 224                         return 0;
 225                 }
 226                 printk(KERN_ERR "kAFS: unparsable volume name\n");
 227                 return -EINVAL;
 228         }
 229
 230         /* determine the type of volume we're looking for */
 231         if (name[0] == '%') {
 232                 ctx->type = AFSVL_RWVOL;
 233                 ctx->force = true;
 234         }
 235         name++;
 236
 237         /* split the cell name out if there is one */
 238         ctx->volname = strchr(name, ':');
 239         if (ctx->volname) {
 240                 cellname = name;
 241                 cellnamesz = ctx->volname - name;
 242                 ctx->volname++;
 243         } else {
 244                 ctx->volname = name;
 245                 cellname = NULL;
 246                 cellnamesz = 0;
 247         }
 248
 249         /* the volume type is further affected by a possible suffix */
 250         suffix = strrchr(ctx->volname, '.');
 251         if (suffix) {
 252                 if (strcmp(suffix, ".readonly") == 0) {
 253                         ctx->type = AFSVL_ROVOL;
 254                         ctx->force = true;
 255                 } else if (strcmp(suffix, ".backup") == 0) {
 256                         ctx->type = AFSVL_BACKVOL;
 257                         ctx->force = true;
 258                 } else if (suffix[1] == 0) {
 259                 } else {
 260                         suffix = NULL;
 261                 }
 262         }
 263
 264         ctx->volnamesz = suffix ?
 265                 suffix - ctx->volname : strlen(ctx->volname);
 266
 267         _debug("cell %*.*s [%p]",
 268                cellnamesz, cellnamesz, cellname ?: "", ctx->cell);
 269
 270         /* lookup the cell record */
 271         if (cellname) {
 272                 cell = afs_lookup_cell(ctx->net, cellname, cellnamesz,
 273                                        NULL, false);
 274                 if (IS_ERR(cell)) {
 275                         pr_err("kAFS: unable to lookup cell '%*.*s'\n",
 276                                cellnamesz, cellnamesz, cellname ?: "");
 277                         return PTR_ERR(cell);
 278                 }
 279                 afs_put_cell(ctx->net, ctx->cell);
 280                 ctx->cell = cell;
 281         }
 282
 283         _debug("CELL:%s [%p] VOLUME:%*.*s SUFFIX:%s TYPE:%d%s",
 284                ctx->cell->name, ctx->cell,
 285                ctx->volnamesz, ctx->volnamesz, ctx->volname,
 286                suffix ?: "-", ctx->type, ctx->force ? " FORCE" : "");
 287
 288         fc->source = param->string;
 289         param->string = NULL;
 290         return 0;
 291 }
 292
 293 /*
 294  * Parse a single mount parameter.
 295  */
 296 static int afs_parse_param(struct fs_context *fc, struct fs_parameter *param)
 297 {
 298         struct fs_parse_result result;
 299         struct afs_fs_context *ctx = fc->fs_private;
 300         int opt;
 301
 302         opt = fs_parse(fc, &afs_fs_parameters, param, &result);
 303         if (opt < 0)
 304                 return opt;
 305
 306         switch (opt) {
 307         case Opt_source:
 308                 return afs_parse_source(fc, param);
 309
 310         case Opt_autocell:
 311                 ctx->autocell = true;
 312                 break;
 313
 314         case Opt_dyn:
 315                 ctx->dyn_root = true;
 316                 break;
 317
 318         default:
 319                 return -EINVAL;
 320         }
 321
 322         _leave(" = 0");
 323         return 0;
 324 }
 325
 326 /*
 327  * Validate the options, get the cell key and look up the volume.
 328  */
 329 static int afs_validate_fc(struct fs_context *fc)
 330 {
 331         struct afs_fs_context *ctx = fc->fs_private;
 332         struct afs_volume *volume;
 333         struct key *key;
 334
 335         if (!ctx->dyn_root) {
 336                 if (ctx->no_cell) {
 337                         pr_warn("kAFS: Can only specify source 'none' with -o dyn\n");
 338                         return -EINVAL;
 339                 }
 340
 341                 if (!ctx->cell) {
 342                         pr_warn("kAFS: No cell specified\n");
 343                         return -EDESTADDRREQ;
 344                 }
 345
 346                 /* We try to do the mount securely. */
 347                 key = afs_request_key(ctx->cell);
 348                 if (IS_ERR(key))
 349                         return PTR_ERR(key);
 350
 351                 ctx->key = key;
 352
 353                 if (ctx->volume) {
 354                         afs_put_volume(ctx->cell, ctx->volume);
 355                         ctx->volume = NULL;
 356                 }
 357
 358                 volume = afs_create_volume(ctx);
 359                 if (IS_ERR(volume))
 360                         return PTR_ERR(volume);
 361
 362                 ctx->volume = volume;
 363         }
 364
 365         return 0;
 366 }
 367
 368 /*
 369  * check a superblock to see if it's the one we're looking for
 370  */
 371 static int afs_test_super(struct super_block *sb, struct fs_context *fc)
 372 {
 373         struct afs_fs_context *ctx = fc->fs_private;
 374         struct afs_super_info *as = AFS_FS_S(sb);
 375
 376         return (as->net_ns == fc->net_ns &&
 377                 as->volume &&
 378                 as->volume->vid == ctx->volume->vid &&
 379                 !as->dyn_root);
 380 }
 381
 382 static int afs_dynroot_test_super(struct super_block *sb, struct fs_context *fc)
 383 {
 384         struct afs_super_info *as = AFS_FS_S(sb);
 385
 386         return (as->net_ns == fc->net_ns &&
 387                 as->dyn_root);
 388 }
 389
 390 static int afs_set_super(struct super_block *sb, struct fs_context *fc)
 391 {
 392         return set_anon_super(sb, NULL);
 393 }
 394
 395 /*
 396  * fill in the superblock
 397  */
 398 static int afs_fill_super(struct super_block *sb, struct afs_fs_context *ctx)
 399 {
 400         struct afs_super_info *as = AFS_FS_S(sb);
 401         struct afs_fid fid;
 402         struct inode *inode = NULL;
 403         int ret;
 404
 405         _enter("");
 406
 407         /* fill in the superblock */
 408         sb->s_blocksize         = PAGE_SIZE;
 409         sb->s_blocksize_bits    = PAGE_SHIFT;
 410         sb->s_magic             = AFS_FS_MAGIC;
 411         sb->s_op                = &afs_super_ops;
 412         if (!as->dyn_root)
 413                 sb->s_xattr     = afs_xattr_handlers;
 414         ret = super_setup_bdi(sb);
 415         if (ret)
 416                 return ret;
 417         sb->s_bdi->ra_pages     = VM_READAHEAD_PAGES;
 418
 419         /* allocate the root inode and dentry */
 420         if (as->dyn_root) {
 421                 inode = afs_iget_pseudo_dir(sb, true);
 422                 sb->s_flags     |= SB_RDONLY;
 423         } else {
 424                 sprintf(sb->s_id, "%llu", as->volume->vid);
 425                 afs_activate_volume(as->volume);
 426                 fid.vid         = as->volume->vid;
 427                 fid.vnode       = 1;
 428                 fid.vnode_hi    = 0;
 429                 fid.unique      = 1;
 430                 inode = afs_iget(sb, ctx->key, &fid, NULL, NULL, NULL);
 431         }
 432
 433         if (IS_ERR(inode))
 434                 return PTR_ERR(inode);
 435
 436         if (ctx->autocell || as->dyn_root)
 437                 set_bit(AFS_VNODE_AUTOCELL, &AFS_FS_I(inode)->flags);
 438
 439         ret = -ENOMEM;
 440         sb->s_root = d_make_root(inode);
 441         if (!sb->s_root)
 442                 goto error;
 443
 444         if (as->dyn_root) {
 445                 sb->s_d_op = &afs_dynroot_dentry_operations;
 446                 ret = afs_dynroot_populate(sb);
 447                 if (ret < 0)
 448                         goto error;
 449         } else {
 450                 sb->s_d_op = &afs_fs_dentry_operations;
 451         }
 452
 453         _leave(" = 0");
 454         return 0;
 455
 456 error:
 457         _leave(" = %d", ret);
 458         return ret;
 459 }
 460
 461 static struct afs_super_info *afs_alloc_sbi(struct fs_context *fc)
 462 {
 463         struct afs_fs_context *ctx = fc->fs_private;
 464         struct afs_super_info *as;
 465
 466         as = kzalloc(sizeof(struct afs_super_info), GFP_KERNEL);
 467         if (as) {
 468                 as->net_ns = get_net(fc->net_ns);
 469                 if (ctx->dyn_root) {
 470                         as->dyn_root = true;
 471                 } else {
 472                         as->cell = afs_get_cell(ctx->cell);
 473                         as->volume = __afs_get_volume(ctx->volume);
 474                 }
 475         }
 476         return as;
 477 }
 478
 479 static void afs_destroy_sbi(struct afs_super_info *as)
 480 {
 481         if (as) {
 482                 afs_put_volume(as->cell, as->volume);
 483                 afs_put_cell(afs_net(as->net_ns), as->cell);
 484                 put_net(as->net_ns);
 485                 kfree(as);
 486         }
 487 }
 488
 489 static void afs_kill_super(struct super_block *sb)
 490 {
 491         struct afs_super_info *as = AFS_FS_S(sb);
 492         struct afs_net *net = afs_net(as->net_ns);
 493
 494         if (as->dyn_root)
 495                 afs_dynroot_depopulate(sb);
 496
 497         /* Clear the callback interests (which will do ilookup5) before
 498          * deactivating the superblock.
 499          */
 500         if (as->volume)
 501                 afs_clear_callback_interests(net, as->volume->servers);
 502         kill_anon_super(sb);
 503         if (as->volume)
 504                 afs_deactivate_volume(as->volume);
 505         afs_destroy_sbi(as);
 506 }
 507
 508 /*
 509  * Get an AFS superblock and root directory.
 510  */
 511 static int afs_get_tree(struct fs_context *fc)
 512 {
 513         struct afs_fs_context *ctx = fc->fs_private;
 514         struct super_block *sb;
 515         struct afs_super_info *as;
 516         int ret;
 517
 518         ret = afs_validate_fc(fc);
 519         if (ret)
 520                 goto error;
 521
 522         _enter("");
 523
 524         /* allocate a superblock info record */
 525         ret = -ENOMEM;
 526         as = afs_alloc_sbi(fc);
 527         if (!as)
 528                 goto error;
 529         fc->s_fs_info = as;
 530
 531         /* allocate a deviceless superblock */
 532         sb = sget_fc(fc,
 533                      as->dyn_root ? afs_dynroot_test_super : afs_test_super,
 534                      afs_set_super);
 535         if (IS_ERR(sb)) {
 536                 ret = PTR_ERR(sb);
 537                 goto error;
 538         }
 539
 540         if (!sb->s_root) {
 541                 /* initial superblock/root creation */
 542                 _debug("create");
 543                 ret = afs_fill_super(sb, ctx);
 544                 if (ret < 0)
 545                         goto error_sb;
 546                 sb->s_flags |= SB_ACTIVE;
 547         } else {
 548                 _debug("reuse");
 549                 ASSERTCMP(sb->s_flags, &, SB_ACTIVE);
 550         }
 551
 552         fc->root = dget(sb->s_root);
 553         _leave(" = 0 [%p]", sb);
 554         return 0;
 555
 556 error_sb:
 557         deactivate_locked_super(sb);
 558 error:
 559         _leave(" = %d", ret);
 560         return ret;
 561 }
 562
 563 static void afs_free_fc(struct fs_context *fc)
 564 {
 565         struct afs_fs_context *ctx = fc->fs_private;
 566
 567         afs_destroy_sbi(fc->s_fs_info);
 568         afs_put_volume(ctx->cell, ctx->volume);
 569         afs_put_cell(ctx->net, ctx->cell);
 570         key_put(ctx->key);
 571         kfree(ctx);
 572 }
 573
 574 static const struct fs_context_operations afs_context_ops = {
 575         .free           = afs_free_fc,
 576         .parse_param    = afs_parse_param,
 577         .get_tree       = afs_get_tree,
 578 };
 579
 580 /*
 581  * Set up the filesystem mount context.
 582  */
 583 static int afs_init_fs_context(struct fs_context *fc)
 584 {
 585         struct afs_fs_context *ctx;
 586         struct afs_cell *cell;
 587
 588         ctx = kzalloc(sizeof(struct afs_fs_context), GFP_KERNEL);
 589         if (!ctx)
 590                 return -ENOMEM;
 591
 592         ctx->type = AFSVL_ROVOL;
 593         ctx->net = afs_net(fc->net_ns);
 594
 595         /* Default to the workstation cell. */
 596         rcu_read_lock();
 597         cell = afs_lookup_cell_rcu(ctx->net, NULL, 0);
 598         rcu_read_unlock();
 599         if (IS_ERR(cell))
 600                 cell = NULL;
 601         ctx->cell = cell;
 602
 603         fc->fs_private = ctx;
 604         fc->ops = &afs_context_ops;
 605         return 0;
 606 }
 607
 608 /*
 609  * Initialise an inode cache slab element prior to any use.  Note that
 610  * afs_alloc_inode() *must* reset anything that could incorrectly leak from one
 611  * inode to another.
 612  */
 613 static void afs_i_init_once(void *_vnode)
 614 {
 615         struct afs_vnode *vnode = _vnode;
 616
 617         memset(vnode, 0, sizeof(*vnode));
 618         inode_init_once(&vnode->vfs_inode);
 619         mutex_init(&vnode->io_lock);
 620         init_rwsem(&vnode->validate_lock);
 621         spin_lock_init(&vnode->wb_lock);
 622         spin_lock_init(&vnode->lock);
 623         INIT_LIST_HEAD(&vnode->wb_keys);
 624         INIT_LIST_HEAD(&vnode->pending_locks);
 625         INIT_LIST_HEAD(&vnode->granted_locks);
 626         INIT_DELAYED_WORK(&vnode->lock_work, afs_lock_work);
 627         seqlock_init(&vnode->cb_lock);
 628 }
 629
 630 /*
 631  * allocate an AFS inode struct from our slab cache
 632  */
 633 static struct inode *afs_alloc_inode(struct super_block *sb)
 634 {
 635         struct afs_vnode *vnode;
 636
 637         vnode = kmem_cache_alloc(afs_inode_cachep, GFP_KERNEL);
 638         if (!vnode)
 639                 return NULL;
 640
 641         atomic_inc(&afs_count_active_inodes);
 642
 643         /* Reset anything that shouldn't leak from one inode to the next. */
 644         memset(&vnode->fid, 0, sizeof(vnode->fid));
 645         memset(&vnode->status, 0, sizeof(vnode->status));
 646
 647         vnode->volume           = NULL;
 648         vnode->lock_key         = NULL;
 649         vnode->permit_cache     = NULL;
 650         vnode->cb_interest      = NULL;
 651 #ifdef CONFIG_AFS_FSCACHE
 652         vnode->cache            = NULL;
 653 #endif
 654
 655         vnode->flags            = 1 << AFS_VNODE_UNSET;
 656         vnode->cb_type          = 0;
 657         vnode->lock_state       = AFS_VNODE_LOCK_NONE;
 658
 659         _leave(" = %p", &vnode->vfs_inode);
 660         return &vnode->vfs_inode;
 661 }
 662
 663 static void afs_i_callback(struct rcu_head *head)
 664 {
 665         struct inode *inode = container_of(head, struct inode, i_rcu);
 666         struct afs_vnode *vnode = AFS_FS_I(inode);
 667         kmem_cache_free(afs_inode_cachep, vnode);
 668 }
 669
 670 /*
 671  * destroy an AFS inode struct
 672  */
 673 static void afs_destroy_inode(struct inode *inode)
 674 {
 675         struct afs_vnode *vnode = AFS_FS_I(inode);
 676
 677         _enter("%p{%llx:%llu}", inode, vnode->fid.vid, vnode->fid.vnode);
 678
 679         _debug("DESTROY INODE %p", inode);
 680
 681         ASSERTCMP(vnode->cb_interest, ==, NULL);
 682
 683         call_rcu(&inode->i_rcu, afs_i_callback);
 684         atomic_dec(&afs_count_active_inodes);
 685 }
 686
 687 /*
 688  * return information about an AFS volume
 689  */
 690 static int afs_statfs(struct dentry *dentry, struct kstatfs *buf)
 691 {
 692         struct afs_super_info *as = AFS_FS_S(dentry->d_sb);
 693         struct afs_fs_cursor fc;
 694         struct afs_volume_status vs;
 695         struct afs_vnode *vnode = AFS_FS_I(d_inode(dentry));
 696         struct key *key;
 697         int ret;
 698
 699         buf->f_type     = dentry->d_sb->s_magic;
 700         buf->f_bsize    = AFS_BLOCK_SIZE;
 701         buf->f_namelen  = AFSNAMEMAX - 1;
 702
 703         if (as->dyn_root) {
 704                 buf->f_blocks   = 1;
 705                 buf->f_bavail   = 0;
 706                 buf->f_bfree    = 0;
 707                 return 0;
 708         }
 709
 710         key = afs_request_key(vnode->volume->cell);
 711         if (IS_ERR(key))
 712                 return PTR_ERR(key);
 713
 714         ret = -ERESTARTSYS;
 715         if (afs_begin_vnode_operation(&fc, vnode, key)) {
 716                 fc.flags |= AFS_FS_CURSOR_NO_VSLEEP;
 717                 while (afs_select_fileserver(&fc)) {
 718                         fc.cb_break = afs_calc_vnode_cb_break(vnode);
 719                         afs_fs_get_volume_status(&fc, &vs);
 720                 }
 721
 722                 afs_check_for_remote_deletion(&fc, fc.vnode);
 723                 afs_vnode_commit_status(&fc, vnode, fc.cb_break);
 724                 ret = afs_end_vnode_operation(&fc);
 725         }
 726
 727         key_put(key);
 728
 729         if (ret == 0) {
 730                 if (vs.max_quota == 0)
 731                         buf->f_blocks = vs.part_max_blocks;
 732                 else
 733                         buf->f_blocks = vs.max_quota;
 734                 buf->f_bavail = buf->f_bfree = buf->f_blocks - vs.blocks_in_use;
 735         }
 736
 737         return ret;
 738 }