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