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