fs/afs/cell.c

   1 /* AFS cell and server record management
   2  *
   3  * Copyright (C) 2002 Red Hat, Inc. All Rights Reserved.
   4  * Written by David Howells (dhowells@redhat.com)
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License
   8  * as published by the Free Software Foundation; either version
   9  * 2 of the License, or (at your option) any later version.
  10  */
  11
  12 #include <linux/module.h>
  13 #include <linux/slab.h>
  14 #include <linux/key.h>
  15 #include <linux/ctype.h>
  16 #include <linux/sched.h>
  17 #include <keys/rxrpc-type.h>
  18 #include "internal.h"
  19
  20 DECLARE_RWSEM(afs_proc_cells_sem);
  21 LIST_HEAD(afs_proc_cells);
  22
  23 static LIST_HEAD(afs_cells);
  24 static DEFINE_RWLOCK(afs_cells_lock);
  25 static DECLARE_RWSEM(afs_cells_sem); /* add/remove serialisation */
  26 static DECLARE_WAIT_QUEUE_HEAD(afs_cells_freeable_wq);
  27 static struct afs_cell *afs_cell_root;
  28
  29 /*
  30  * allocate a cell record and fill in its name, VL server address list and
  31  * allocate an anonymous key
  32  */
  33 static struct afs_cell *afs_cell_alloc(const char *name, char *vllist)
  34 {
  35         struct afs_cell *cell;
  36         struct key *key;
  37         size_t namelen;
  38         char keyname[4 + AFS_MAXCELLNAME + 1], *cp, *dp, *next;
  39         int ret;
  40
  41         _enter("%s,%s", name, vllist);
  42
  43         BUG_ON(!name); /* TODO: want to look up "this cell" in the cache */
  44
  45         namelen = strlen(name);
  46         if (namelen > AFS_MAXCELLNAME)
  47                 return ERR_PTR(-ENAMETOOLONG);
  48
  49         /* allocate and initialise a cell record */
  50         cell = kzalloc(sizeof(struct afs_cell) + namelen + 1, GFP_KERNEL);
  51         if (!cell) {
  52                 _leave(" = -ENOMEM");
  53                 return ERR_PTR(-ENOMEM);
  54         }
  55
  56         memcpy(cell->name, name, namelen);
  57         cell->name[namelen] = 0;
  58
  59         atomic_set(&cell->usage, 1);
  60         INIT_LIST_HEAD(&cell->link);
  61         rwlock_init(&cell->servers_lock);
  62         INIT_LIST_HEAD(&cell->servers);
  63         init_rwsem(&cell->vl_sem);
  64         INIT_LIST_HEAD(&cell->vl_list);
  65         spin_lock_init(&cell->vl_lock);
  66
  67         /* fill in the VL server list from the rest of the string */
  68         do {
  69                 unsigned a, b, c, d;
  70
  71                 next = strchr(vllist, ':');
  72                 if (next)
  73                         *next++ = 0;
  74
  75                 if (sscanf(vllist, "%u.%u.%u.%u", &a, &b, &c, &d) != 4)
  76                         goto bad_address;
  77
  78                 if (a > 255 || b > 255 || c > 255 || d > 255)
  79                         goto bad_address;
  80
  81                 cell->vl_addrs[cell->vl_naddrs++].s_addr =
  82                         htonl((a << 24) | (b << 16) | (c << 8) | d);
  83
  84         } while (cell->vl_naddrs < AFS_CELL_MAX_ADDRS && (vllist = next));
  85
  86         /* create a key to represent an anonymous user */
  87         memcpy(keyname, "afs@", 4);
  88         dp = keyname + 4;
  89         cp = cell->name;
  90         do {
  91                 *dp++ = toupper(*cp);
  92         } while (*cp++);
  93
  94         key = rxrpc_get_null_key(keyname);
  95         if (IS_ERR(key)) {
  96                 _debug("no key");
  97                 ret = PTR_ERR(key);
  98                 goto error;
  99         }
 100         cell->anonymous_key = key;
 101
 102         _debug("anon key %p{%x}",
 103                cell->anonymous_key, key_serial(cell->anonymous_key));
 104
 105         _leave(" = %p", cell);
 106         return cell;
 107
 108 bad_address:
 109         printk(KERN_ERR "kAFS: bad VL server IP address\n");
 110         ret = -EINVAL;
 111 error:
 112         key_put(cell->anonymous_key);
 113         kfree(cell);
 114         _leave(" = %d", ret);
 115         return ERR_PTR(ret);
 116 }
 117
 118 /*
 119  * create a cell record
 120  * - "name" is the name of the cell
 121  * - "vllist" is a colon separated list of IP addresses in "a.b.c.d" format
 122  */
 123 struct afs_cell *afs_cell_create(const char *name, char *vllist)
 124 {
 125         struct afs_cell *cell;
 126         int ret;
 127
 128         _enter("%s,%s", name, vllist);
 129
 130         down_write(&afs_cells_sem);
 131         read_lock(&afs_cells_lock);
 132         list_for_each_entry(cell, &afs_cells, link) {
 133                 if (strcasecmp(cell->name, name) == 0)
 134                         goto duplicate_name;
 135         }
 136         read_unlock(&afs_cells_lock);
 137
 138         cell = afs_cell_alloc(name, vllist);
 139         if (IS_ERR(cell)) {
 140                 _leave(" = %ld", PTR_ERR(cell));
 141                 up_write(&afs_cells_sem);
 142                 return cell;
 143         }
 144
 145         /* add a proc directory for this cell */
 146         ret = afs_proc_cell_setup(cell);
 147         if (ret < 0)
 148                 goto error;
 149
 150 #ifdef CONFIG_AFS_FSCACHE
 151         /* put it up for caching (this never returns an error) */
 152         cell->cache = fscache_acquire_cookie(afs_cache_netfs.primary_index,
 153                                              &afs_cell_cache_index_def,
 154                                              cell);
 155 #endif
 156
 157         /* add to the cell lists */
 158         write_lock(&afs_cells_lock);
 159         list_add_tail(&cell->link, &afs_cells);
 160         write_unlock(&afs_cells_lock);
 161
 162         down_write(&afs_proc_cells_sem);
 163         list_add_tail(&cell->proc_link, &afs_proc_cells);
 164         up_write(&afs_proc_cells_sem);
 165         up_write(&afs_cells_sem);
 166
 167         _leave(" = %p", cell);
 168         return cell;
 169
 170 error:
 171         up_write(&afs_cells_sem);
 172         key_put(cell->anonymous_key);
 173         kfree(cell);
 174         _leave(" = %d", ret);
 175         return ERR_PTR(ret);
 176
 177 duplicate_name:
 178         read_unlock(&afs_cells_lock);
 179         up_write(&afs_cells_sem);
 180         return ERR_PTR(-EEXIST);
 181 }
 182
 183 /*
 184  * set the root cell information
 185  * - can be called with a module parameter string
 186  * - can be called from a write to /proc/fs/afs/rootcell
 187  */
 188 int afs_cell_init(char *rootcell)
 189 {
 190         struct afs_cell *old_root, *new_root;
 191         char *cp;
 192
 193         _enter("");
 194
 195         if (!rootcell) {
 196                 /* module is loaded with no parameters, or built statically.
 197                  * - in the future we might initialize cell DB here.
 198                  */
 199                 _leave(" = 0 [no root]");
 200                 return 0;
 201         }
 202
 203         cp = strchr(rootcell, ':');
 204         if (!cp) {
 205                 printk(KERN_ERR "kAFS: no VL server IP addresses specified\n");
 206                 _leave(" = -EINVAL");
 207                 return -EINVAL;
 208         }
 209
 210         /* allocate a cell record for the root cell */
 211         *cp++ = 0;
 212         new_root = afs_cell_create(rootcell, cp);
 213         if (IS_ERR(new_root)) {
 214                 _leave(" = %ld", PTR_ERR(new_root));
 215                 return PTR_ERR(new_root);
 216         }
 217
 218         /* install the new cell */
 219         write_lock(&afs_cells_lock);
 220         old_root = afs_cell_root;
 221         afs_cell_root = new_root;
 222         write_unlock(&afs_cells_lock);
 223         afs_put_cell(old_root);
 224
 225         _leave(" = 0");
 226         return 0;
 227 }
 228
 229 /*
 230  * lookup a cell record
 231  */
 232 struct afs_cell *afs_cell_lookup(const char *name, unsigned namesz)
 233 {
 234         struct afs_cell *cell;
 235
 236         _enter("\"%*.*s\",", namesz, namesz, name ? name : "");
 237
 238         down_read(&afs_cells_sem);
 239         read_lock(&afs_cells_lock);
 240
 241         if (name) {
 242                 /* if the cell was named, look for it in the cell record list */
 243                 list_for_each_entry(cell, &afs_cells, link) {
 244                         if (strncmp(cell->name, name, namesz) == 0) {
 245                                 afs_get_cell(cell);
 246                                 goto found;
 247                         }
 248                 }
 249                 cell = ERR_PTR(-ENOENT);
 250         found:
 251                 ;
 252         } else {
 253                 cell = afs_cell_root;
 254                 if (!cell) {
 255                         /* this should not happen unless user tries to mount
 256                          * when root cell is not set. Return an impossibly
 257                          * bizzare errno to alert the user. Things like
 258                          * ENOENT might be "more appropriate" but they happen
 259                          * for other reasons.
 260                          */
 261                         cell = ERR_PTR(-EDESTADDRREQ);
 262                 } else {
 263                         afs_get_cell(cell);
 264                 }
 265
 266         }
 267
 268         read_unlock(&afs_cells_lock);
 269         up_read(&afs_cells_sem);
 270         _leave(" = %p", cell);
 271         return cell;
 272 }
 273
 274 #if 0
 275 /*
 276  * try and get a cell record
 277  */
 278 struct afs_cell *afs_get_cell_maybe(struct afs_cell *cell)
 279 {
 280         write_lock(&afs_cells_lock);
 281
 282         if (cell && !list_empty(&cell->link))
 283                 afs_get_cell(cell);
 284         else
 285                 cell = NULL;
 286
 287         write_unlock(&afs_cells_lock);
 288         return cell;
 289 }
 290 #endif  /*  0  */
 291
 292 /*
 293  * destroy a cell record
 294  */
 295 void afs_put_cell(struct afs_cell *cell)
 296 {
 297         if (!cell)
 298                 return;
 299
 300         _enter("%p{%d,%s}", cell, atomic_read(&cell->usage), cell->name);
 301
 302         ASSERTCMP(atomic_read(&cell->usage), >, 0);
 303
 304         /* to prevent a race, the decrement and the dequeue must be effectively
 305          * atomic */
 306         write_lock(&afs_cells_lock);
 307
 308         if (likely(!atomic_dec_and_test(&cell->usage))) {
 309                 write_unlock(&afs_cells_lock);
 310                 _leave("");
 311                 return;
 312         }
 313
 314         ASSERT(list_empty(&cell->servers));
 315         ASSERT(list_empty(&cell->vl_list));
 316
 317         write_unlock(&afs_cells_lock);
 318
 319         wake_up(&afs_cells_freeable_wq);
 320
 321         _leave(" [unused]");
 322 }
 323
 324 /*
 325  * destroy a cell record
 326  * - must be called with the afs_cells_sem write-locked
 327  * - cell->link should have been broken by the caller
 328  */
 329 static void afs_cell_destroy(struct afs_cell *cell)
 330 {
 331         _enter("%p{%d,%s}", cell, atomic_read(&cell->usage), cell->name);
 332
 333         ASSERTCMP(atomic_read(&cell->usage), >=, 0);
 334         ASSERT(list_empty(&cell->link));
 335
 336         /* wait for everyone to stop using the cell */
 337         if (atomic_read(&cell->usage) > 0) {
 338                 DECLARE_WAITQUEUE(myself, current);
 339
 340                 _debug("wait for cell %s", cell->name);
 341                 set_current_state(TASK_UNINTERRUPTIBLE);
 342                 add_wait_queue(&afs_cells_freeable_wq, &myself);
 343
 344                 while (atomic_read(&cell->usage) > 0) {
 345                         schedule();
 346                         set_current_state(TASK_UNINTERRUPTIBLE);
 347                 }
 348
 349                 remove_wait_queue(&afs_cells_freeable_wq, &myself);
 350                 set_current_state(TASK_RUNNING);
 351         }
 352
 353         _debug("cell dead");
 354         ASSERTCMP(atomic_read(&cell->usage), ==, 0);
 355         ASSERT(list_empty(&cell->servers));
 356         ASSERT(list_empty(&cell->vl_list));
 357
 358         afs_proc_cell_remove(cell);
 359
 360         down_write(&afs_proc_cells_sem);
 361         list_del_init(&cell->proc_link);
 362         up_write(&afs_proc_cells_sem);
 363
 364 #ifdef CONFIG_AFS_FSCACHE
 365         fscache_relinquish_cookie(cell->cache, 0);
 366 #endif
 367         key_put(cell->anonymous_key);
 368         kfree(cell);
 369
 370         _leave(" [destroyed]");
 371 }
 372
 373 /*
 374  * purge in-memory cell database on module unload or afs_init() failure
 375  * - the timeout daemon is stopped before calling this
 376  */
 377 void afs_cell_purge(void)
 378 {
 379         struct afs_cell *cell;
 380
 381         _enter("");
 382
 383         afs_put_cell(afs_cell_root);
 384
 385         down_write(&afs_cells_sem);
 386
 387         while (!list_empty(&afs_cells)) {
 388                 cell = NULL;
 389
 390                 /* remove the next cell from the front of the list */
 391                 write_lock(&afs_cells_lock);
 392
 393                 if (!list_empty(&afs_cells)) {
 394                         cell = list_entry(afs_cells.next,
 395                                           struct afs_cell, link);
 396                         list_del_init(&cell->link);
 397                 }
 398
 399                 write_unlock(&afs_cells_lock);
 400
 401                 if (cell) {
 402                         _debug("PURGING CELL %s (%d)",
 403                                cell->name, atomic_read(&cell->usage));
 404
 405                         /* now the cell should be left with no references */
 406                         afs_cell_destroy(cell);
 407                 }
 408         }
 409
 410         up_write(&afs_cells_sem);
 411         _leave("");
 412 }