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 "internal.h"
  25
  26 #define AFS_FS_MAGIC 0x6B414653 /* 'kAFS' */
  27
  28 static void afs_i_init_once(void *foo, struct kmem_cache *cachep,
  29                             unsigned long flags);
  30
  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
  35 static struct inode *afs_alloc_inode(struct super_block *sb);
  36
  37 static void afs_put_super(struct super_block *sb);
  38
  39 static void afs_destroy_inode(struct inode *inode);
  40
  41 struct file_system_type afs_fs_type = {
  42         .owner          = THIS_MODULE,
  43         .name           = "afs",
  44         .get_sb         = afs_get_sb,
  45         .kill_sb        = kill_anon_super,
  46         .fs_flags       = 0,
  47 };
  48
  49 static const struct super_operations afs_super_ops = {
  50         .statfs         = simple_statfs,
  51         .alloc_inode    = afs_alloc_inode,
  52         .drop_inode     = generic_delete_inode,
  53         .destroy_inode  = afs_destroy_inode,
  54         .clear_inode    = afs_clear_inode,
  55         .umount_begin   = afs_umount_begin,
  56         .put_super      = afs_put_super,
  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 };
  68
  69 static const match_table_t afs_options_list = {
  70         { afs_opt_cell,         "cell=%s"       },
  71         { afs_opt_rwpath,       "rwpath"        },
  72         { afs_opt_vol,          "vol=%s"        },
  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                                              NULL);
  95         if (!afs_inode_cachep) {
  96                 printk(KERN_NOTICE "kAFS: Failed to allocate inode cache\n");
  97                 return ret;
  98         }
  99
 100         /* now export our filesystem to lesser mortals */
 101         ret = register_filesystem(&afs_fs_type);
 102         if (ret < 0) {
 103                 kmem_cache_destroy(afs_inode_cachep);
 104                 _leave(" = %d", ret);
 105                 return ret;
 106         }
 107
 108         _leave(" = 0");
 109         return 0;
 110 }
 111
 112 /*
 113  * clean up the filesystem
 114  */
 115 void __exit afs_fs_exit(void)
 116 {
 117         _enter("");
 118
 119         afs_mntpt_kill_timer();
 120         unregister_filesystem(&afs_fs_type);
 121
 122         if (atomic_read(&afs_count_active_inodes) != 0) {
 123                 printk("kAFS: %d active inode objects still present\n",
 124                        atomic_read(&afs_count_active_inodes));
 125                 BUG();
 126         }
 127
 128         kmem_cache_destroy(afs_inode_cachep);
 129         _leave("");
 130 }
 131
 132 /*
 133  * parse the mount options
 134  * - this function has been shamelessly adapted from the ext3 fs which
 135  *   shamelessly adapted it from the msdos fs
 136  */
 137 static int afs_parse_options(struct afs_mount_params *params,
 138                              char *options, const char **devname)
 139 {
 140         struct afs_cell *cell;
 141         substring_t args[MAX_OPT_ARGS];
 142         char *p;
 143         int token;
 144
 145         _enter("%s", options);
 146
 147         options[PAGE_SIZE - 1] = 0;
 148
 149         while ((p = strsep(&options, ","))) {
 150                 if (!*p)
 151                         continue;
 152
 153                 token = match_token(p, afs_options_list, args);
 154                 switch (token) {
 155                 case afs_opt_cell:
 156                         cell = afs_cell_lookup(args[0].from,
 157                                                args[0].to - args[0].from);
 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                 default:
 173                         printk(KERN_ERR "kAFS:"
 174                                " Unknown or invalid mount option: '%s'\n", p);
 175                         return -EINVAL;
 176                 }
 177         }
 178
 179         _leave(" = 0");
 180         return 0;
 181 }
 182
 183 /*
 184  * parse a device name to get cell name, volume name, volume type and R/W
 185  * selector
 186  * - this can be one of the following:
 187  *      "%[cell:]volume[.]"             R/W volume
 188  *      "#[cell:]volume[.]"             R/O or R/W volume (rwpath=0),
 189  *                                       or R/W (rwpath=1) volume
 190  *      "%[cell:]volume.readonly"       R/O volume
 191  *      "#[cell:]volume.readonly"       R/O volume
 192  *      "%[cell:]volume.backup"         Backup volume
 193  *      "#[cell:]volume.backup"         Backup volume
 194  */
 195 static int afs_parse_device_name(struct afs_mount_params *params,
 196                                  const char *name)
 197 {
 198         struct afs_cell *cell;
 199         const char *cellname, *suffix;
 200         int cellnamesz;
 201
 202         _enter(",%s", name);
 203
 204         if (!name) {
 205                 printk(KERN_ERR "kAFS: no volume name specified\n");
 206                 return -EINVAL;
 207         }
 208
 209         if ((name[0] != '%' && name[0] != '#') || !name[1]) {
 210                 printk(KERN_ERR "kAFS: unparsable volume name\n");
 211                 return -EINVAL;
 212         }
 213
 214         /* determine the type of volume we're looking for */
 215         params->type = AFSVL_ROVOL;
 216         params->force = false;
 217         if (params->rwpath || name[0] == '%') {
 218                 params->type = AFSVL_RWVOL;
 219                 params->force = true;
 220         }
 221         name++;
 222
 223         /* split the cell name out if there is one */
 224         params->volname = strchr(name, ':');
 225         if (params->volname) {
 226                 cellname = name;
 227                 cellnamesz = params->volname - name;
 228                 params->volname++;
 229         } else {
 230                 params->volname = name;
 231                 cellname = NULL;
 232                 cellnamesz = 0;
 233         }
 234
 235         /* the volume type is further affected by a possible suffix */
 236         suffix = strrchr(params->volname, '.');
 237         if (suffix) {
 238                 if (strcmp(suffix, ".readonly") == 0) {
 239                         params->type = AFSVL_ROVOL;
 240                         params->force = true;
 241                 } else if (strcmp(suffix, ".backup") == 0) {
 242                         params->type = AFSVL_BACKVOL;
 243                         params->force = true;
 244                 } else if (suffix[1] == 0) {
 245                 } else {
 246                         suffix = NULL;
 247                 }
 248         }
 249
 250         params->volnamesz = suffix ?
 251                 suffix - params->volname : strlen(params->volname);
 252
 253         _debug("cell %*.*s [%p]",
 254                cellnamesz, cellnamesz, cellname ?: "", params->cell);
 255
 256         /* lookup the cell record */
 257         if (cellname || !params->cell) {
 258                 cell = afs_cell_lookup(cellname, cellnamesz);
 259                 if (IS_ERR(cell)) {
 260                         printk(KERN_ERR "kAFS: unable to lookup cell '%s'\n",
 261                                cellname ?: "");
 262                         return PTR_ERR(cell);
 263                 }
 264                 afs_put_cell(params->cell);
 265                 params->cell = cell;
 266         }
 267
 268         _debug("CELL:%s [%p] VOLUME:%*.*s SUFFIX:%s TYPE:%d%s",
 269                params->cell->name, params->cell,
 270                params->volnamesz, params->volnamesz, params->volname,
 271                suffix ?: "-", params->type, params->force ? " FORCE" : "");
 272
 273         return 0;
 274 }
 275
 276 /*
 277  * check a superblock to see if it's the one we're looking for
 278  */
 279 static int afs_test_super(struct super_block *sb, void *data)
 280 {
 281         struct afs_mount_params *params = data;
 282         struct afs_super_info *as = sb->s_fs_info;
 283
 284         return as->volume == params->volume;
 285 }
 286
 287 /*
 288  * fill in the superblock
 289  */
 290 static int afs_fill_super(struct super_block *sb, void *data)
 291 {
 292         struct afs_mount_params *params = data;
 293         struct afs_super_info *as = NULL;
 294         struct afs_fid fid;
 295         struct dentry *root = NULL;
 296         struct inode *inode = NULL;
 297         int ret;
 298
 299         _enter("");
 300
 301         /* allocate a superblock info record */
 302         as = kzalloc(sizeof(struct afs_super_info), GFP_KERNEL);
 303         if (!as) {
 304                 _leave(" = -ENOMEM");
 305                 return -ENOMEM;
 306         }
 307
 308         afs_get_volume(params->volume);
 309         as->volume = params->volume;
 310
 311         /* fill in the superblock */
 312         sb->s_blocksize         = PAGE_CACHE_SIZE;
 313         sb->s_blocksize_bits    = PAGE_CACHE_SHIFT;
 314         sb->s_magic             = AFS_FS_MAGIC;
 315         sb->s_op                = &afs_super_ops;
 316         sb->s_fs_info           = as;
 317
 318         /* allocate the root inode and dentry */
 319         fid.vid         = as->volume->vid;
 320         fid.vnode       = 1;
 321         fid.unique      = 1;
 322         inode = afs_iget(sb, params->key, &fid, NULL, NULL);
 323         if (IS_ERR(inode))
 324                 goto error_inode;
 325
 326         ret = -ENOMEM;
 327         root = d_alloc_root(inode);
 328         if (!root)
 329                 goto error;
 330
 331         sb->s_root = root;
 332
 333         _leave(" = 0");
 334         return 0;
 335
 336 error_inode:
 337         ret = PTR_ERR(inode);
 338         inode = NULL;
 339 error:
 340         iput(inode);
 341         afs_put_volume(as->volume);
 342         kfree(as);
 343
 344         sb->s_fs_info = NULL;
 345
 346         _leave(" = %d", ret);
 347         return ret;
 348 }
 349
 350 /*
 351  * get an AFS superblock
 352  */
 353 static int afs_get_sb(struct file_system_type *fs_type,
 354                       int flags,
 355                       const char *dev_name,
 356                       void *options,
 357                       struct vfsmount *mnt)
 358 {
 359         struct afs_mount_params params;
 360         struct super_block *sb;
 361         struct afs_volume *vol;
 362         struct key *key;
 363         int ret;
 364
 365         _enter(",,%s,%p", dev_name, options);
 366
 367         memset(&params, 0, sizeof(params));
 368
 369         /* parse the options and device name */
 370         if (options) {
 371                 ret = afs_parse_options(&params, options, &dev_name);
 372                 if (ret < 0)
 373                         goto error;
 374         }
 375
 376         ret = afs_parse_device_name(&params, dev_name);
 377         if (ret < 0)
 378                 goto error;
 379
 380         /* try and do the mount securely */
 381         key = afs_request_key(params.cell);
 382         if (IS_ERR(key)) {
 383                 _leave(" = %ld [key]", PTR_ERR(key));
 384                 ret = PTR_ERR(key);
 385                 goto error;
 386         }
 387         params.key = key;
 388
 389         /* parse the device name */
 390         vol = afs_volume_lookup(&params);
 391         if (IS_ERR(vol)) {
 392                 ret = PTR_ERR(vol);
 393                 goto error;
 394         }
 395         params.volume = vol;
 396
 397         /* allocate a deviceless superblock */
 398         sb = sget(fs_type, afs_test_super, set_anon_super, &params);
 399         if (IS_ERR(sb)) {
 400                 ret = PTR_ERR(sb);
 401                 goto error;
 402         }
 403
 404         if (!sb->s_root) {
 405                 /* initial superblock/root creation */
 406                 _debug("create");
 407                 sb->s_flags = flags;
 408                 ret = afs_fill_super(sb, &params);
 409                 if (ret < 0) {
 410                         up_write(&sb->s_umount);
 411                         deactivate_super(sb);
 412                         goto error;
 413                 }
 414                 sb->s_flags |= MS_ACTIVE;
 415         } else {
 416                 _debug("reuse");
 417                 ASSERTCMP(sb->s_flags, &, MS_ACTIVE);
 418         }
 419
 420         simple_set_mnt(mnt, sb);
 421         afs_put_volume(params.volume);
 422         afs_put_cell(params.cell);
 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         _leave(" = %d", ret);
 431         return ret;
 432 }
 433
 434 /*
 435  * finish the unmounting process on the superblock
 436  */
 437 static void afs_put_super(struct super_block *sb)
 438 {
 439         struct afs_super_info *as = sb->s_fs_info;
 440
 441         _enter("");
 442
 443         afs_put_volume(as->volume);
 444
 445         _leave("");
 446 }
 447
 448 /*
 449  * initialise an inode cache slab element prior to any use
 450  */
 451 static void afs_i_init_once(void *_vnode, struct kmem_cache *cachep,
 452                             unsigned long flags)
 453 {
 454         struct afs_vnode *vnode = _vnode;
 455
 456         if (flags & SLAB_CTOR_CONSTRUCTOR) {
 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->lock);
 463                 INIT_WORK(&vnode->cb_broken_work, afs_broken_callback_work);
 464         }
 465 }
 466
 467 /*
 468  * allocate an AFS inode struct from our slab cache
 469  */
 470 static struct inode *afs_alloc_inode(struct super_block *sb)
 471 {
 472         struct afs_vnode *vnode;
 473
 474         vnode = kmem_cache_alloc(afs_inode_cachep, GFP_KERNEL);
 475         if (!vnode)
 476                 return NULL;
 477
 478         atomic_inc(&afs_count_active_inodes);
 479
 480         memset(&vnode->fid, 0, sizeof(vnode->fid));
 481         memset(&vnode->status, 0, sizeof(vnode->status));
 482
 483         vnode->volume           = NULL;
 484         vnode->update_cnt       = 0;
 485         vnode->flags            = 1 << AFS_VNODE_UNSET;
 486         vnode->cb_promised      = false;
 487
 488         return &vnode->vfs_inode;
 489 }
 490
 491 /*
 492  * destroy an AFS inode struct
 493  */
 494 static void afs_destroy_inode(struct inode *inode)
 495 {
 496         struct afs_vnode *vnode = AFS_FS_I(inode);
 497
 498         _enter("{%lu}", inode->i_ino);
 499
 500         _debug("DESTROY INODE %p", inode);
 501
 502         ASSERTCMP(vnode->server, ==, NULL);
 503
 504         kmem_cache_free(afs_inode_cachep, vnode);
 505         atomic_dec(&afs_count_active_inodes);
 506 }