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 "internal.h"
  28
  29 #define AFS_FS_MAGIC 0x6B414653 /* 'kAFS' */
  30
  31 static void afs_i_init_once(void *foo);
  32 static struct dentry *afs_mount(struct file_system_type *fs_type,
  33                       int flags, const char *dev_name, void *data);
  34 static struct inode *afs_alloc_inode(struct super_block *sb);
  35 static void afs_put_super(struct super_block *sb);
  36 static void afs_destroy_inode(struct inode *inode);
  37 static int afs_statfs(struct dentry *dentry, struct kstatfs *buf);
  38
  39 struct file_system_type afs_fs_type = {
  40         .owner          = THIS_MODULE,
  41         .name           = "afs",
  42         .mount          = afs_mount,
  43         .kill_sb        = kill_anon_super,
  44         .fs_flags       = 0,
  45 };
  46
  47 static const struct super_operations afs_super_ops = {
  48         .statfs         = afs_statfs,
  49         .alloc_inode    = afs_alloc_inode,
  50         .drop_inode     = afs_drop_inode,
  51         .destroy_inode  = afs_destroy_inode,
  52         .evict_inode    = afs_evict_inode,
  53         .put_super      = afs_put_super,
  54         .show_options   = generic_show_options,
  55 };
  56
  57 static struct kmem_cache *afs_inode_cachep;
  58 static atomic_t afs_count_active_inodes;
  59
  60 enum {
  61         afs_no_opt,
  62         afs_opt_cell,
  63         afs_opt_rwpath,
  64         afs_opt_vol,
  65         afs_opt_autocell,
  66 };
  67
  68 static const match_table_t afs_options_list = {
  69         { afs_opt_cell,         "cell=%s"       },
  70         { afs_opt_rwpath,       "rwpath"        },
  71         { afs_opt_vol,          "vol=%s"        },
  72         { afs_opt_autocell,     "autocell"      },
  73         { afs_no_opt,           NULL            },
  74 };
  75
  76 /*
  77  * initialise the filesystem
  78  */
  79 int __init afs_fs_init(void)
  80 {
  81         int ret;
  82
  83         _enter("");
  84
  85         /* create ourselves an inode cache */
  86         atomic_set(&afs_count_active_inodes, 0);
  87
  88         ret = -ENOMEM;
  89         afs_inode_cachep = kmem_cache_create("afs_inode_cache",
  90                                              sizeof(struct afs_vnode),
  91                                              0,
  92                                              SLAB_HWCACHE_ALIGN,
  93                                              afs_i_init_once);
  94         if (!afs_inode_cachep) {
  95                 printk(KERN_NOTICE "kAFS: Failed to allocate inode cache\n");
  96                 return ret;
  97         }
  98
  99         /* now export our filesystem to lesser mortals */
 100         ret = register_filesystem(&afs_fs_type);
 101         if (ret < 0) {
 102                 kmem_cache_destroy(afs_inode_cachep);
 103                 _leave(" = %d", ret);
 104                 return ret;
 105         }
 106
 107         _leave(" = 0");
 108         return 0;
 109 }
 110
 111 /*
 112  * clean up the filesystem
 113  */
 114 void __exit afs_fs_exit(void)
 115 {
 116         _enter("");
 117
 118         afs_mntpt_kill_timer();
 119         unregister_filesystem(&afs_fs_type);
 120
 121         if (atomic_read(&afs_count_active_inodes) != 0) {
 122                 printk("kAFS: %d active inode objects still present\n",
 123                        atomic_read(&afs_count_active_inodes));
 124                 BUG();
 125         }
 126
 127         kmem_cache_destroy(afs_inode_cachep);
 128         _leave("");
 129 }
 130
 131 /*
 132  * parse the mount options
 133  * - this function has been shamelessly adapted from the ext3 fs which
 134  *   shamelessly adapted it from the msdos fs
 135  */
 136 static int afs_parse_options(struct afs_mount_params *params,
 137                              char *options, const char **devname)
 138 {
 139         struct afs_cell *cell;
 140         substring_t args[MAX_OPT_ARGS];
 141         char *p;
 142         int token;
 143
 144         _enter("%s", options);
 145
 146         options[PAGE_SIZE - 1] = 0;
 147
 148         while ((p = strsep(&options, ","))) {
 149                 if (!*p)
 150                         continue;
 151
 152                 token = match_token(p, afs_options_list, args);
 153                 switch (token) {
 154                 case afs_opt_cell:
 155                         cell = afs_cell_lookup(args[0].from,
 156                                                args[0].to - args[0].from,
 157                                                false);
 158                         if (IS_ERR(cell))
 159                                 return PTR_ERR(cell);
 160                         afs_put_cell(params->cell);
 161                         params->cell = cell;
 162                         break;
 163
 164                 case afs_opt_rwpath:
 165                         params->rwpath = 1;
 166                         break;
 167
 168                 case afs_opt_vol:
 169                         *devname = args[0].from;
 170                         break;
 171
 172                 case afs_opt_autocell:
 173                         params->autocell = 1;
 174                         break;
 175
 176                 default:
 177                         printk(KERN_ERR "kAFS:"
 178                                " Unknown or invalid mount option: '%s'\n", p);
 179                         return -EINVAL;
 180                 }
 181         }
 182
 183         _leave(" = 0");
 184         return 0;
 185 }
 186
 187 /*
 188  * parse a device name to get cell name, volume name, volume type and R/W
 189  * selector
 190  * - this can be one of the following:
 191  *      "%[cell:]volume[.]"             R/W volume
 192  *      "#[cell:]volume[.]"             R/O or R/W volume (rwpath=0),
 193  *                                       or R/W (rwpath=1) volume
 194  *      "%[cell:]volume.readonly"       R/O volume
 195  *      "#[cell:]volume.readonly"       R/O volume
 196  *      "%[cell:]volume.backup"         Backup volume
 197  *      "#[cell:]volume.backup"         Backup volume
 198  */
 199 static int afs_parse_device_name(struct afs_mount_params *params,
 200                                  const char *name)
 201 {
 202         struct afs_cell *cell;
 203         const char *cellname, *suffix;
 204         int cellnamesz;
 205
 206         _enter(",%s", name);
 207
 208         if (!name) {
 209                 printk(KERN_ERR "kAFS: no volume name specified\n");
 210                 return -EINVAL;
 211         }
 212
 213         if ((name[0] != '%' && name[0] != '#') || !name[1]) {
 214                 printk(KERN_ERR "kAFS: unparsable volume name\n");
 215                 return -EINVAL;
 216         }
 217
 218         /* determine the type of volume we're looking for */
 219         params->type = AFSVL_ROVOL;
 220         params->force = false;
 221         if (params->rwpath || name[0] == '%') {
 222                 params->type = AFSVL_RWVOL;
 223                 params->force = true;
 224         }
 225         name++;
 226
 227         /* split the cell name out if there is one */
 228         params->volname = strchr(name, ':');
 229         if (params->volname) {
 230                 cellname = name;
 231                 cellnamesz = params->volname - name;
 232                 params->volname++;
 233         } else {
 234                 params->volname = name;
 235                 cellname = NULL;
 236                 cellnamesz = 0;
 237         }
 238
 239         /* the volume type is further affected by a possible suffix */
 240         suffix = strrchr(params->volname, '.');
 241         if (suffix) {
 242                 if (strcmp(suffix, ".readonly") == 0) {
 243                         params->type = AFSVL_ROVOL;
 244                         params->force = true;
 245                 } else if (strcmp(suffix, ".backup") == 0) {
 246                         params->type = AFSVL_BACKVOL;
 247                         params->force = true;
 248                 } else if (suffix[1] == 0) {
 249                 } else {
 250                         suffix = NULL;
 251                 }
 252         }
 253
 254         params->volnamesz = suffix ?
 255                 suffix - params->volname : strlen(params->volname);
 256
 257         _debug("cell %*.*s [%p]",
 258                cellnamesz, cellnamesz, cellname ?: "", params->cell);
 259
 260         /* lookup the cell record */
 261         if (cellname || !params->cell) {
 262                 cell = afs_cell_lookup(cellname, cellnamesz, true);
 263                 if (IS_ERR(cell)) {
 264                         printk(KERN_ERR "kAFS: unable to lookup cell '%*.*s'\n",
 265                                cellnamesz, cellnamesz, cellname ?: "");
 266                         return PTR_ERR(cell);
 267                 }
 268                 afs_put_cell(params->cell);
 269                 params->cell = cell;
 270         }
 271
 272         _debug("CELL:%s [%p] VOLUME:%*.*s SUFFIX:%s TYPE:%d%s",
 273                params->cell->name, params->cell,
 274                params->volnamesz, params->volnamesz, params->volname,
 275                suffix ?: "-", params->type, params->force ? " FORCE" : "");
 276
 277         return 0;
 278 }
 279
 280 /*
 281  * check a superblock to see if it's the one we're looking for
 282  */
 283 static int afs_test_super(struct super_block *sb, void *data)
 284 {
 285         struct afs_mount_params *params = data;
 286         struct afs_super_info *as = sb->s_fs_info;
 287
 288         return as->volume == params->volume;
 289 }
 290
 291 /*
 292  * fill in the superblock
 293  */
 294 static int afs_fill_super(struct super_block *sb, void *data)
 295 {
 296         struct afs_mount_params *params = data;
 297         struct afs_super_info *as = NULL;
 298         struct afs_fid fid;
 299         struct dentry *root = NULL;
 300         struct inode *inode = NULL;
 301         int ret;
 302
 303         _enter("");
 304
 305         /* allocate a superblock info record */
 306         as = kzalloc(sizeof(struct afs_super_info), GFP_KERNEL);
 307         if (!as) {
 308                 _leave(" = -ENOMEM");
 309                 return -ENOMEM;
 310         }
 311
 312         afs_get_volume(params->volume);
 313         as->volume = params->volume;
 314
 315         /* fill in the superblock */
 316         sb->s_blocksize         = PAGE_CACHE_SIZE;
 317         sb->s_blocksize_bits    = PAGE_CACHE_SHIFT;
 318         sb->s_magic             = AFS_FS_MAGIC;
 319         sb->s_op                = &afs_super_ops;
 320         sb->s_fs_info           = as;
 321         sb->s_bdi               = &as->volume->bdi;
 322
 323         /* allocate the root inode and dentry */
 324         fid.vid         = as->volume->vid;
 325         fid.vnode       = 1;
 326         fid.unique      = 1;
 327         inode = afs_iget(sb, params->key, &fid, NULL, NULL);
 328         if (IS_ERR(inode))
 329                 goto error_inode;
 330
 331         if (params->autocell)
 332                 set_bit(AFS_VNODE_AUTOCELL, &AFS_FS_I(inode)->flags);
 333
 334         ret = -ENOMEM;
 335         root = d_alloc_root(inode);
 336         if (!root)
 337                 goto error;
 338
 339         sb->s_d_op = &afs_fs_dentry_operations;
 340         sb->s_root = root;
 341
 342         _leave(" = 0");
 343         return 0;
 344
 345 error_inode:
 346         ret = PTR_ERR(inode);
 347         inode = NULL;
 348 error:
 349         iput(inode);
 350         afs_put_volume(as->volume);
 351         kfree(as);
 352
 353         sb->s_fs_info = NULL;
 354
 355         _leave(" = %d", ret);
 356         return ret;
 357 }
 358
 359 /*
 360  * get an AFS superblock
 361  */
 362 static struct dentry *afs_mount(struct file_system_type *fs_type,
 363                       int flags, const char *dev_name, void *options)
 364 {
 365         struct afs_mount_params params;
 366         struct super_block *sb;
 367         struct afs_volume *vol;
 368         struct key *key;
 369         char *new_opts = kstrdup(options, GFP_KERNEL);
 370         int ret;
 371
 372         _enter(",,%s,%p", dev_name, options);
 373
 374         memset(&params, 0, sizeof(params));
 375
 376         /* parse the options and device name */
 377         if (options) {
 378                 ret = afs_parse_options(&params, options, &dev_name);
 379                 if (ret < 0)
 380                         goto error;
 381         }
 382
 383         ret = afs_parse_device_name(&params, dev_name);
 384         if (ret < 0)
 385                 goto error;
 386
 387         /* try and do the mount securely */
 388         key = afs_request_key(params.cell);
 389         if (IS_ERR(key)) {
 390                 _leave(" = %ld [key]", PTR_ERR(key));
 391                 ret = PTR_ERR(key);
 392                 goto error;
 393         }
 394         params.key = key;
 395
 396         /* parse the device name */
 397         vol = afs_volume_lookup(&params);
 398         if (IS_ERR(vol)) {
 399                 ret = PTR_ERR(vol);
 400                 goto error;
 401         }
 402         params.volume = vol;
 403
 404         /* allocate a deviceless superblock */
 405         sb = sget(fs_type, afs_test_super, set_anon_super, &params);
 406         if (IS_ERR(sb)) {
 407                 ret = PTR_ERR(sb);
 408                 goto error;
 409         }
 410
 411         if (!sb->s_root) {
 412                 /* initial superblock/root creation */
 413                 _debug("create");
 414                 sb->s_flags = flags;
 415                 ret = afs_fill_super(sb, &params);
 416                 if (ret < 0) {
 417                         deactivate_locked_super(sb);
 418                         goto error;
 419                 }
 420                 save_mount_options(sb, new_opts);
 421                 sb->s_flags |= MS_ACTIVE;
 422         } else {
 423                 _debug("reuse");
 424                 ASSERTCMP(sb->s_flags, &, MS_ACTIVE);
 425         }
 426
 427         afs_put_volume(params.volume);
 428         afs_put_cell(params.cell);
 429         kfree(new_opts);
 430         _leave(" = 0 [%p]", sb);
 431         return dget(sb->s_root);
 432
 433 error:
 434         afs_put_volume(params.volume);
 435         afs_put_cell(params.cell);
 436         key_put(params.key);
 437         kfree(new_opts);
 438         _leave(" = %d", ret);
 439         return ERR_PTR(ret);
 440 }
 441
 442 /*
 443  * finish the unmounting process on the superblock
 444  */
 445 static void afs_put_super(struct super_block *sb)
 446 {
 447         struct afs_super_info *as = sb->s_fs_info;
 448
 449         _enter("");
 450
 451         afs_put_volume(as->volume);
 452
 453         _leave("");
 454 }
 455
 456 /*
 457  * initialise an inode cache slab element prior to any use
 458  */
 459 static void afs_i_init_once(void *_vnode)
 460 {
 461         struct afs_vnode *vnode = _vnode;
 462
 463         memset(vnode, 0, sizeof(*vnode));
 464         inode_init_once(&vnode->vfs_inode);
 465         init_waitqueue_head(&vnode->update_waitq);
 466         mutex_init(&vnode->permits_lock);
 467         mutex_init(&vnode->validate_lock);
 468         spin_lock_init(&vnode->writeback_lock);
 469         spin_lock_init(&vnode->lock);
 470         INIT_LIST_HEAD(&vnode->writebacks);
 471         INIT_LIST_HEAD(&vnode->pending_locks);
 472         INIT_LIST_HEAD(&vnode->granted_locks);
 473         INIT_DELAYED_WORK(&vnode->lock_work, afs_lock_work);
 474         INIT_WORK(&vnode->cb_broken_work, afs_broken_callback_work);
 475 }
 476
 477 /*
 478  * allocate an AFS inode struct from our slab cache
 479  */
 480 static struct inode *afs_alloc_inode(struct super_block *sb)
 481 {
 482         struct afs_vnode *vnode;
 483
 484         vnode = kmem_cache_alloc(afs_inode_cachep, GFP_KERNEL);
 485         if (!vnode)
 486                 return NULL;
 487
 488         atomic_inc(&afs_count_active_inodes);
 489
 490         memset(&vnode->fid, 0, sizeof(vnode->fid));
 491         memset(&vnode->status, 0, sizeof(vnode->status));
 492
 493         vnode->volume           = NULL;
 494         vnode->update_cnt       = 0;
 495         vnode->flags            = 1 << AFS_VNODE_UNSET;
 496         vnode->cb_promised      = false;
 497
 498         _leave(" = %p", &vnode->vfs_inode);
 499         return &vnode->vfs_inode;
 500 }
 501
 502 static void afs_i_callback(struct rcu_head *head)
 503 {
 504         struct inode *inode = container_of(head, struct inode, i_rcu);
 505         struct afs_vnode *vnode = AFS_FS_I(inode);
 506         INIT_LIST_HEAD(&inode->i_dentry);
 507         kmem_cache_free(afs_inode_cachep, vnode);
 508 }
 509
 510 /*
 511  * destroy an AFS inode struct
 512  */
 513 static void afs_destroy_inode(struct inode *inode)
 514 {
 515         struct afs_vnode *vnode = AFS_FS_I(inode);
 516
 517         _enter("%p{%x:%u}", inode, vnode->fid.vid, vnode->fid.vnode);
 518
 519         _debug("DESTROY INODE %p", inode);
 520
 521         ASSERTCMP(vnode->server, ==, NULL);
 522
 523         call_rcu(&inode->i_rcu, afs_i_callback);
 524         atomic_dec(&afs_count_active_inodes);
 525 }
 526
 527 /*
 528  * return information about an AFS volume
 529  */
 530 static int afs_statfs(struct dentry *dentry, struct kstatfs *buf)
 531 {
 532         struct afs_volume_status vs;
 533         struct afs_vnode *vnode = AFS_FS_I(dentry->d_inode);
 534         struct key *key;
 535         int ret;
 536
 537         key = afs_request_key(vnode->volume->cell);
 538         if (IS_ERR(key))
 539                 return PTR_ERR(key);
 540
 541         ret = afs_vnode_get_volume_status(vnode, key, &vs);
 542         key_put(key);
 543         if (ret < 0) {
 544                 _leave(" = %d", ret);
 545                 return ret;
 546         }
 547
 548         buf->f_type     = dentry->d_sb->s_magic;
 549         buf->f_bsize    = AFS_BLOCK_SIZE;
 550         buf->f_namelen  = AFSNAMEMAX - 1;
 551
 552         if (vs.max_quota == 0)
 553                 buf->f_blocks = vs.part_max_blocks;
 554         else
 555                 buf->f_blocks = vs.max_quota;
 556         buf->f_bavail = buf->f_bfree = buf->f_blocks - vs.blocks_in_use;
 557         return 0;
 558 }