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         .write_inode    = afs_write_inode,
  54         .destroy_inode  = afs_destroy_inode,
  55         .clear_inode    = afs_clear_inode,
  56         .umount_begin   = afs_umount_begin,
  57         .put_super      = afs_put_super,
  58 };
  59
  60 static struct kmem_cache *afs_inode_cachep;
  61 static atomic_t afs_count_active_inodes;
  62
  63 enum {
  64         afs_no_opt,
  65         afs_opt_cell,
  66         afs_opt_rwpath,
  67         afs_opt_vol,
  68 };
  69
  70 static 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_no_opt,           NULL            },
  75 };
  76
  77 /*
  78  * initialise the filesystem
  79  */
  80 int __init afs_fs_init(void)
  81 {
  82         int ret;
  83
  84         _enter("");
  85
  86         /* create ourselves an inode cache */
  87         atomic_set(&afs_count_active_inodes, 0);
  88
  89         ret = -ENOMEM;
  90         afs_inode_cachep = kmem_cache_create("afs_inode_cache",
  91                                              sizeof(struct afs_vnode),
  92                                              0,
  93                                              SLAB_HWCACHE_ALIGN,
  94                                              afs_i_init_once,
  95                                              NULL);
  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         kmem_cache_destroy(afs_inode_cachep);
 130         _leave("");
 131 }
 132
 133 /*
 134  * parse the mount options
 135  * - this function has been shamelessly adapted from the ext3 fs which
 136  *   shamelessly adapted it from the msdos fs
 137  */
 138 static int afs_parse_options(struct afs_mount_params *params,
 139                              char *options, const char **devname)
 140 {
 141         struct afs_cell *cell;
 142         substring_t args[MAX_OPT_ARGS];
 143         char *p;
 144         int token;
 145
 146         _enter("%s", options);
 147
 148         options[PAGE_SIZE - 1] = 0;
 149
 150         while ((p = strsep(&options, ","))) {
 151                 if (!*p)
 152                         continue;
 153
 154                 token = match_token(p, afs_options_list, args);
 155                 switch (token) {
 156                 case afs_opt_cell:
 157                         cell = afs_cell_lookup(args[0].from,
 158                                                args[0].to - args[0].from);
 159                         if (IS_ERR(cell))
 160                                 return PTR_ERR(cell);
 161                         afs_put_cell(params->cell);
 162                         params->cell = cell;
 163                         break;
 164
 165                 case afs_opt_rwpath:
 166                         params->rwpath = 1;
 167                         break;
 168
 169                 case afs_opt_vol:
 170                         *devname = args[0].from;
 171                         break;
 172
 173                 default:
 174                         printk(KERN_ERR "kAFS:"
 175                                " Unknown or invalid mount option: '%s'\n", p);
 176                         return -EINVAL;
 177                 }
 178         }
 179
 180         _leave(" = 0");
 181         return 0;
 182 }
 183
 184 /*
 185  * parse a device name to get cell name, volume name, volume type and R/W
 186  * selector
 187  * - this can be one of the following:
 188  *      "%[cell:]volume[.]"             R/W volume
 189  *      "#[cell:]volume[.]"             R/O or R/W volume (rwpath=0),
 190  *                                       or R/W (rwpath=1) volume
 191  *      "%[cell:]volume.readonly"       R/O volume
 192  *      "#[cell:]volume.readonly"       R/O volume
 193  *      "%[cell:]volume.backup"         Backup volume
 194  *      "#[cell:]volume.backup"         Backup volume
 195  */
 196 static int afs_parse_device_name(struct afs_mount_params *params,
 197                                  const char *name)
 198 {
 199         struct afs_cell *cell;
 200         const char *cellname, *suffix;
 201         int cellnamesz;
 202
 203         _enter(",%s", name);
 204
 205         if (!name) {
 206                 printk(KERN_ERR "kAFS: no volume name specified\n");
 207                 return -EINVAL;
 208         }
 209
 210         if ((name[0] != '%' && name[0] != '#') || !name[1]) {
 211                 printk(KERN_ERR "kAFS: unparsable volume name\n");
 212                 return -EINVAL;
 213         }
 214
 215         /* determine the type of volume we're looking for */
 216         params->type = AFSVL_ROVOL;
 217         params->force = false;
 218         if (params->rwpath || name[0] == '%') {
 219                 params->type = AFSVL_RWVOL;
 220                 params->force = true;
 221         }
 222         name++;
 223
 224         /* split the cell name out if there is one */
 225         params->volname = strchr(name, ':');
 226         if (params->volname) {
 227                 cellname = name;
 228                 cellnamesz = params->volname - name;
 229                 params->volname++;
 230         } else {
 231                 params->volname = name;
 232                 cellname = NULL;
 233                 cellnamesz = 0;
 234         }
 235
 236         /* the volume type is further affected by a possible suffix */
 237         suffix = strrchr(params->volname, '.');
 238         if (suffix) {
 239                 if (strcmp(suffix, ".readonly") == 0) {
 240                         params->type = AFSVL_ROVOL;
 241                         params->force = true;
 242                 } else if (strcmp(suffix, ".backup") == 0) {
 243                         params->type = AFSVL_BACKVOL;
 244                         params->force = true;
 245                 } else if (suffix[1] == 0) {
 246                 } else {
 247                         suffix = NULL;
 248                 }
 249         }
 250
 251         params->volnamesz = suffix ?
 252                 suffix - params->volname : strlen(params->volname);
 253
 254         _debug("cell %*.*s [%p]",
 255                cellnamesz, cellnamesz, cellname ?: "", params->cell);
 256
 257         /* lookup the cell record */
 258         if (cellname || !params->cell) {
 259                 cell = afs_cell_lookup(cellname, cellnamesz);
 260                 if (IS_ERR(cell)) {
 261                         printk(KERN_ERR "kAFS: unable to lookup cell '%s'\n",
 262                                cellname ?: "");
 263                         return PTR_ERR(cell);
 264                 }
 265                 afs_put_cell(params->cell);
 266                 params->cell = cell;
 267         }
 268
 269         _debug("CELL:%s [%p] VOLUME:%*.*s SUFFIX:%s TYPE:%d%s",
 270                params->cell->name, params->cell,
 271                params->volnamesz, params->volnamesz, params->volname,
 272                suffix ?: "-", params->type, params->force ? " FORCE" : "");
 273
 274         return 0;
 275 }
 276
 277 /*
 278  * check a superblock to see if it's the one we're looking for
 279  */
 280 static int afs_test_super(struct super_block *sb, void *data)
 281 {
 282         struct afs_mount_params *params = data;
 283         struct afs_super_info *as = sb->s_fs_info;
 284
 285         return as->volume == params->volume;
 286 }
 287
 288 /*
 289  * fill in the superblock
 290  */
 291 static int afs_fill_super(struct super_block *sb, void *data)
 292 {
 293         struct afs_mount_params *params = data;
 294         struct afs_super_info *as = NULL;
 295         struct afs_fid fid;
 296         struct dentry *root = NULL;
 297         struct inode *inode = NULL;
 298         int ret;
 299
 300         _enter("");
 301
 302         /* allocate a superblock info record */
 303         as = kzalloc(sizeof(struct afs_super_info), GFP_KERNEL);
 304         if (!as) {
 305                 _leave(" = -ENOMEM");
 306                 return -ENOMEM;
 307         }
 308
 309         afs_get_volume(params->volume);
 310         as->volume = params->volume;
 311
 312         /* fill in the superblock */
 313         sb->s_blocksize         = PAGE_CACHE_SIZE;
 314         sb->s_blocksize_bits    = PAGE_CACHE_SHIFT;
 315         sb->s_magic             = AFS_FS_MAGIC;
 316         sb->s_op                = &afs_super_ops;
 317         sb->s_fs_info           = as;
 318
 319         /* allocate the root inode and dentry */
 320         fid.vid         = as->volume->vid;
 321         fid.vnode       = 1;
 322         fid.unique      = 1;
 323         inode = afs_iget(sb, params->key, &fid, NULL, NULL);
 324         if (IS_ERR(inode))
 325                 goto error_inode;
 326
 327         ret = -ENOMEM;
 328         root = d_alloc_root(inode);
 329         if (!root)
 330                 goto error;
 331
 332         sb->s_root = root;
 333
 334         _leave(" = 0");
 335         return 0;
 336
 337 error_inode:
 338         ret = PTR_ERR(inode);
 339         inode = NULL;
 340 error:
 341         iput(inode);
 342         afs_put_volume(as->volume);
 343         kfree(as);
 344
 345         sb->s_fs_info = NULL;
 346
 347         _leave(" = %d", ret);
 348         return ret;
 349 }
 350
 351 /*
 352  * get an AFS superblock
 353  */
 354 static int afs_get_sb(struct file_system_type *fs_type,
 355                       int flags,
 356                       const char *dev_name,
 357                       void *options,
 358                       struct vfsmount *mnt)
 359 {
 360         struct afs_mount_params params;
 361         struct super_block *sb;
 362         struct afs_volume *vol;
 363         struct key *key;
 364         int ret;
 365
 366         _enter(",,%s,%p", dev_name, options);
 367
 368         memset(&params, 0, sizeof(params));
 369
 370         /* parse the options and device name */
 371         if (options) {
 372                 ret = afs_parse_options(&params, options, &dev_name);
 373                 if (ret < 0)
 374                         goto error;
 375         }
 376
 377         ret = afs_parse_device_name(&params, dev_name);
 378         if (ret < 0)
 379                 goto error;
 380
 381         /* try and do the mount securely */
 382         key = afs_request_key(params.cell);
 383         if (IS_ERR(key)) {
 384                 _leave(" = %ld [key]", PTR_ERR(key));
 385                 ret = PTR_ERR(key);
 386                 goto error;
 387         }
 388         params.key = key;
 389
 390         /* parse the device name */
 391         vol = afs_volume_lookup(&params);
 392         if (IS_ERR(vol)) {
 393                 ret = PTR_ERR(vol);
 394                 goto error;
 395         }
 396         params.volume = vol;
 397
 398         /* allocate a deviceless superblock */
 399         sb = sget(fs_type, afs_test_super, set_anon_super, &params);
 400         if (IS_ERR(sb)) {
 401                 ret = PTR_ERR(sb);
 402                 goto error;
 403         }
 404
 405         if (!sb->s_root) {
 406                 /* initial superblock/root creation */
 407                 _debug("create");
 408                 sb->s_flags = flags;
 409                 ret = afs_fill_super(sb, &params);
 410                 if (ret < 0) {
 411                         up_write(&sb->s_umount);
 412                         deactivate_super(sb);
 413                         goto error;
 414                 }
 415                 sb->s_flags |= MS_ACTIVE;
 416         } else {
 417                 _debug("reuse");
 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         _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         afs_put_volume(as->volume);
 445
 446         _leave("");
 447 }
 448
 449 /*
 450  * initialise an inode cache slab element prior to any use
 451  */
 452 static void afs_i_init_once(void *_vnode, struct kmem_cache *cachep,
 453                             unsigned long flags)
 454 {
 455         struct afs_vnode *vnode = _vnode;
 456
 457         if (flags & SLAB_CTOR_CONSTRUCTOR) {
 458                 memset(vnode, 0, sizeof(*vnode));
 459                 inode_init_once(&vnode->vfs_inode);
 460                 init_waitqueue_head(&vnode->update_waitq);
 461                 mutex_init(&vnode->permits_lock);
 462                 mutex_init(&vnode->validate_lock);
 463                 spin_lock_init(&vnode->writeback_lock);
 464                 spin_lock_init(&vnode->lock);
 465                 INIT_LIST_HEAD(&vnode->writebacks);
 466                 INIT_WORK(&vnode->cb_broken_work, afs_broken_callback_work);
 467         }
 468 }
 469
 470 /*
 471  * allocate an AFS inode struct from our slab cache
 472  */
 473 static struct inode *afs_alloc_inode(struct super_block *sb)
 474 {
 475         struct afs_vnode *vnode;
 476
 477         vnode = kmem_cache_alloc(afs_inode_cachep, GFP_KERNEL);
 478         if (!vnode)
 479                 return NULL;
 480
 481         atomic_inc(&afs_count_active_inodes);
 482
 483         memset(&vnode->fid, 0, sizeof(vnode->fid));
 484         memset(&vnode->status, 0, sizeof(vnode->status));
 485
 486         vnode->volume           = NULL;
 487         vnode->update_cnt       = 0;
 488         vnode->flags            = 1 << AFS_VNODE_UNSET;
 489         vnode->cb_promised      = false;
 490
 491         return &vnode->vfs_inode;
 492 }
 493
 494 /*
 495  * destroy an AFS inode struct
 496  */
 497 static void afs_destroy_inode(struct inode *inode)
 498 {
 499         struct afs_vnode *vnode = AFS_FS_I(inode);
 500
 501         _enter("{%lu}", inode->i_ino);
 502
 503         _debug("DESTROY INODE %p", inode);
 504
 505         ASSERTCMP(vnode->server, ==, NULL);
 506
 507         kmem_cache_free(afs_inode_cachep, vnode);
 508         atomic_dec(&afs_count_active_inodes);
 509 }