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