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@redhat.com>
  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/fs.h>
  22 #include <linux/pagemap.h>
  23 #include <linux/parser.h>
  24 #include <linux/statfs.h>
  25 #include <linux/sched.h>
  26 #include "internal.h"
  27
  28 #define AFS_FS_MAGIC 0x6B414653 /* 'kAFS' */
  29
  30 static void afs_i_init_once(struct kmem_cache *cachep, void *foo);
  31 static int afs_get_sb(struct file_system_type *fs_type,
  32                       int flags, const char *dev_name,
  33                       void *data, struct vfsmount *mnt);
  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         .get_sb         = afs_get_sb,
  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         .write_inode    = afs_write_inode,
  51         .destroy_inode  = afs_destroy_inode,
  52         .clear_inode    = afs_clear_inode,
  53         .umount_begin   = afs_umount_begin,
  54         .put_super      = afs_put_super,
  55         .show_options   = generic_show_options,
  56 };
  57
  58 static struct kmem_cache *afs_inode_cachep;
  59 static atomic_t afs_count_active_inodes;
  60
  61 enum {
  62         afs_no_opt,
  63         afs_opt_cell,
  64         afs_opt_rwpath,
  65         afs_opt_vol,
  66 };
  67
  68 static 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_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                         if (IS_ERR(cell))
 157                                 return PTR_ERR(cell);
 158                         afs_put_cell(params->cell);
 159                         params->cell = cell;
 160                         break;
 161
 162                 case afs_opt_rwpath:
 163                         params->rwpath = 1;
 164                         break;
 165
 166                 case afs_opt_vol:
 167                         *devname = args[0].from;
 168                         break;
 169
 170                 default:
 171                         printk(KERN_ERR "kAFS:"
 172                                " Unknown or invalid mount option: '%s'\n", p);
 173                         return -EINVAL;
 174                 }
 175         }
 176
 177         _leave(" = 0");
 178         return 0;
 179 }
 180
 181 /*
 182  * parse a device name to get cell name, volume name, volume type and R/W
 183  * selector
 184  * - this can be one of the following:
 185  *      "%[cell:]volume[.]"             R/W volume
 186  *      "#[cell:]volume[.]"             R/O or R/W volume (rwpath=0),
 187  *                                       or R/W (rwpath=1) volume
 188  *      "%[cell:]volume.readonly"       R/O volume
 189  *      "#[cell:]volume.readonly"       R/O volume
 190  *      "%[cell:]volume.backup"         Backup volume
 191  *      "#[cell:]volume.backup"         Backup volume
 192  */
 193 static int afs_parse_device_name(struct afs_mount_params *params,
 194                                  const char *name)
 195 {
 196         struct afs_cell *cell;
 197         const char *cellname, *suffix;
 198         int cellnamesz;
 199
 200         _enter(",%s", name);
 201
 202         if (!name) {
 203                 printk(KERN_ERR "kAFS: no volume name specified\n");
 204                 return -EINVAL;
 205         }
 206
 207         if ((name[0] != '%' && name[0] != '#') || !name[1]) {
 208                 printk(KERN_ERR "kAFS: unparsable volume name\n");
 209                 return -EINVAL;
 210         }
 211
 212         /* determine the type of volume we're looking for */
 213         params->type = AFSVL_ROVOL;
 214         params->force = false;
 215         if (params->rwpath || name[0] == '%') {
 216                 params->type = AFSVL_RWVOL;
 217                 params->force = true;
 218         }
 219         name++;
 220
 221         /* split the cell name out if there is one */
 222         params->volname = strchr(name, ':');
 223         if (params->volname) {
 224                 cellname = name;
 225                 cellnamesz = params->volname - name;
 226                 params->volname++;
 227         } else {
 228                 params->volname = name;
 229                 cellname = NULL;
 230                 cellnamesz = 0;
 231         }
 232
 233         /* the volume type is further affected by a possible suffix */
 234         suffix = strrchr(params->volname, '.');
 235         if (suffix) {
 236                 if (strcmp(suffix, ".readonly") == 0) {
 237                         params->type = AFSVL_ROVOL;
 238                         params->force = true;
 239                 } else if (strcmp(suffix, ".backup") == 0) {
 240                         params->type = AFSVL_BACKVOL;
 241                         params->force = true;
 242                 } else if (suffix[1] == 0) {
 243                 } else {
 244                         suffix = NULL;
 245                 }
 246         }
 247
 248         params->volnamesz = suffix ?
 249                 suffix - params->volname : strlen(params->volname);
 250
 251         _debug("cell %*.*s [%p]",
 252                cellnamesz, cellnamesz, cellname ?: "", params->cell);
 253
 254         /* lookup the cell record */
 255         if (cellname || !params->cell) {
 256                 cell = afs_cell_lookup(cellname, cellnamesz);
 257                 if (IS_ERR(cell)) {
 258                         printk(KERN_ERR "kAFS: unable to lookup cell '%s'\n",
 259                                cellname ?: "");
 260                         return PTR_ERR(cell);
 261                 }
 262                 afs_put_cell(params->cell);
 263                 params->cell = cell;
 264         }
 265
 266         _debug("CELL:%s [%p] VOLUME:%*.*s SUFFIX:%s TYPE:%d%s",
 267                params->cell->name, params->cell,
 268                params->volnamesz, params->volnamesz, params->volname,
 269                suffix ?: "-", params->type, params->force ? " FORCE" : "");
 270
 271         return 0;
 272 }
 273
 274 /*
 275  * check a superblock to see if it's the one we're looking for
 276  */
 277 static int afs_test_super(struct super_block *sb, void *data)
 278 {
 279         struct afs_mount_params *params = data;
 280         struct afs_super_info *as = sb->s_fs_info;
 281
 282         return as->volume == params->volume;
 283 }
 284
 285 /*
 286  * fill in the superblock
 287  */
 288 static int afs_fill_super(struct super_block *sb, void *data)
 289 {
 290         struct afs_mount_params *params = data;
 291         struct afs_super_info *as = NULL;
 292         struct afs_fid fid;
 293         struct dentry *root = NULL;
 294         struct inode *inode = NULL;
 295         int ret;
 296
 297         _enter("");
 298
 299         /* allocate a superblock info record */
 300         as = kzalloc(sizeof(struct afs_super_info), GFP_KERNEL);
 301         if (!as) {
 302                 _leave(" = -ENOMEM");
 303                 return -ENOMEM;
 304         }
 305
 306         afs_get_volume(params->volume);
 307         as->volume = params->volume;
 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_fs_info           = as;
 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                         up_write(&sb->s_umount);
 410                         deactivate_super(sb);
 411                         goto error;
 412                 }
 413                 sb->s_options = new_opts;
 414                 sb->s_flags |= MS_ACTIVE;
 415         } else {
 416                 _debug("reuse");
 417                 kfree(new_opts);
 418                 ASSERTCMP(sb->s_flags, &, MS_ACTIVE);
 419         }
 420
 421         simple_set_mnt(mnt, sb);
 422         afs_put_volume(params.volume);
 423         afs_put_cell(params.cell);
 424         _leave(" = 0 [%p]", sb);
 425         return 0;
 426
 427 error:
 428         afs_put_volume(params.volume);
 429         afs_put_cell(params.cell);
 430         key_put(params.key);
 431         kfree(new_opts);
 432         _leave(" = %d", ret);
 433         return ret;
 434 }
 435
 436 /*
 437  * finish the unmounting process on the superblock
 438  */
 439 static void afs_put_super(struct super_block *sb)
 440 {
 441         struct afs_super_info *as = sb->s_fs_info;
 442
 443         _enter("");
 444
 445         afs_put_volume(as->volume);
 446
 447         _leave("");
 448 }
 449
 450 /*
 451  * initialise an inode cache slab element prior to any use
 452  */
 453 static void afs_i_init_once(struct kmem_cache *cachep, void *_vnode)
 454 {
 455         struct afs_vnode *vnode = _vnode;
 456
 457         memset(vnode, 0, sizeof(*vnode));
 458         inode_init_once(&vnode->vfs_inode);
 459         init_waitqueue_head(&vnode->update_waitq);
 460         mutex_init(&vnode->permits_lock);
 461         mutex_init(&vnode->validate_lock);
 462         spin_lock_init(&vnode->writeback_lock);
 463         spin_lock_init(&vnode->lock);
 464         INIT_LIST_HEAD(&vnode->writebacks);
 465         INIT_LIST_HEAD(&vnode->pending_locks);
 466         INIT_LIST_HEAD(&vnode->granted_locks);
 467         INIT_DELAYED_WORK(&vnode->lock_work, afs_lock_work);
 468         INIT_WORK(&vnode->cb_broken_work, afs_broken_callback_work);
 469 }
 470
 471 /*
 472  * allocate an AFS inode struct from our slab cache
 473  */
 474 static struct inode *afs_alloc_inode(struct super_block *sb)
 475 {
 476         struct afs_vnode *vnode;
 477
 478         vnode = kmem_cache_alloc(afs_inode_cachep, GFP_KERNEL);
 479         if (!vnode)
 480                 return NULL;
 481
 482         atomic_inc(&afs_count_active_inodes);
 483
 484         memset(&vnode->fid, 0, sizeof(vnode->fid));
 485         memset(&vnode->status, 0, sizeof(vnode->status));
 486
 487         vnode->volume           = NULL;
 488         vnode->update_cnt       = 0;
 489         vnode->flags            = 1 << AFS_VNODE_UNSET;
 490         vnode->cb_promised      = false;
 491
 492         _leave(" = %p", &vnode->vfs_inode);
 493         return &vnode->vfs_inode;
 494 }
 495
 496 /*
 497  * destroy an AFS inode struct
 498  */
 499 static void afs_destroy_inode(struct inode *inode)
 500 {
 501         struct afs_vnode *vnode = AFS_FS_I(inode);
 502
 503         _enter("%p{%x:%u}", inode, vnode->fid.vid, vnode->fid.vnode);
 504
 505         _debug("DESTROY INODE %p", inode);
 506
 507         ASSERTCMP(vnode->server, ==, NULL);
 508
 509         kmem_cache_free(afs_inode_cachep, vnode);
 510         atomic_dec(&afs_count_active_inodes);
 511 }
 512
 513 /*
 514  * return information about an AFS volume
 515  */
 516 static int afs_statfs(struct dentry *dentry, struct kstatfs *buf)
 517 {
 518         struct afs_volume_status vs;
 519         struct afs_vnode *vnode = AFS_FS_I(dentry->d_inode);
 520         struct key *key;
 521         int ret;
 522
 523         key = afs_request_key(vnode->volume->cell);
 524         if (IS_ERR(key))
 525                 return PTR_ERR(key);
 526
 527         ret = afs_vnode_get_volume_status(vnode, key, &vs);
 528         key_put(key);
 529         if (ret < 0) {
 530                 _leave(" = %d", ret);
 531                 return ret;
 532         }
 533
 534         buf->f_type     = dentry->d_sb->s_magic;
 535         buf->f_bsize    = AFS_BLOCK_SIZE;
 536         buf->f_namelen  = AFSNAMEMAX - 1;
 537
 538         if (vs.max_quota == 0)
 539                 buf->f_blocks = vs.part_max_blocks;
 540         else
 541                 buf->f_blocks = vs.max_quota;
 542         buf->f_bavail = buf->f_bfree = buf->f_blocks - vs.blocks_in_use;
 543         return 0;
 544 }