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 struct list_head afs_cells = LIST_HEAD_INIT(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 AFS_CACHING_SUPPORT
 151         /* put it up for caching */
 152         cachefs_acquire_cookie(afs_cache_netfs.primary_index,
 153                                &afs_vlocation_cache_index_def,
 154                                cell,
 155                                &cell->cache);
 156 #endif
 157
 158         /* add to the cell lists */
 159         write_lock(&afs_cells_lock);
 160         list_add_tail(&cell->link, &afs_cells);
 161         write_unlock(&afs_cells_lock);
 162
 163         down_write(&afs_proc_cells_sem);
 164         list_add_tail(&cell->proc_link, &afs_proc_cells);
 165         up_write(&afs_proc_cells_sem);
 166         up_write(&afs_cells_sem);
 167
 168         _leave(" = %p", cell);
 169         return cell;
 170
 171 error:
 172         up_write(&afs_cells_sem);
 173         key_put(cell->anonymous_key);
 174         kfree(cell);
 175         _leave(" = %d", ret);
 176         return ERR_PTR(ret);
 177
 178 duplicate_name:
 179         read_unlock(&afs_cells_lock);
 180         up_write(&afs_cells_sem);
 181         return ERR_PTR(-EEXIST);
 182 }
 183
 184 /*
 185  * set the root cell information
 186  * - can be called with a module parameter string
 187  * - can be called from a write to /proc/fs/afs/rootcell
 188  */
 189 int afs_cell_init(char *rootcell)
 190 {
 191         struct afs_cell *old_root, *new_root;
 192         char *cp;
 193
 194         _enter("");
 195
 196         if (!rootcell) {
 197                 /* module is loaded with no parameters, or built statically.
 198                  * - in the future we might initialize cell DB here.
 199                  */
 200                 _leave(" = 0 [no root]");
 201                 return 0;
 202         }
 203
 204         cp = strchr(rootcell, ':');
 205         if (!cp) {
 206                 printk(KERN_ERR "kAFS: no VL server IP addresses specified\n");
 207                 _leave(" = -EINVAL");
 208                 return -EINVAL;
 209         }
 210
 211         /* allocate a cell record for the root cell */
 212         *cp++ = 0;
 213         new_root = afs_cell_create(rootcell, cp);
 214         if (IS_ERR(new_root)) {
 215                 _leave(" = %ld", PTR_ERR(new_root));
 216                 return PTR_ERR(new_root);
 217         }
 218
 219         /* install the new cell */
 220         write_lock(&afs_cells_lock);
 221         old_root = afs_cell_root;
 222         afs_cell_root = new_root;
 223         write_unlock(&afs_cells_lock);
 224         afs_put_cell(old_root);
 225
 226         _leave(" = 0");
 227         return 0;
 228 }
 229
 230 /*
 231  * lookup a cell record
 232  */
 233 struct afs_cell *afs_cell_lookup(const char *name, unsigned namesz)
 234 {
 235         struct afs_cell *cell;
 236
 237         _enter("\"%*.*s\",", namesz, namesz, name ? name : "");
 238
 239         down_read(&afs_cells_sem);
 240         read_lock(&afs_cells_lock);
 241
 242         if (name) {
 243                 /* if the cell was named, look for it in the cell record list */
 244                 list_for_each_entry(cell, &afs_cells, link) {
 245                         if (strncmp(cell->name, name, namesz) == 0) {
 246                                 afs_get_cell(cell);
 247                                 goto found;
 248                         }
 249                 }
 250                 cell = ERR_PTR(-ENOENT);
 251         found:
 252                 ;
 253         } else {
 254                 cell = afs_cell_root;
 255                 if (!cell) {
 256                         /* this should not happen unless user tries to mount
 257                          * when root cell is not set. Return an impossibly
 258                          * bizzare errno to alert the user. Things like
 259                          * ENOENT might be "more appropriate" but they happen
 260                          * for other reasons.
 261                          */
 262                         cell = ERR_PTR(-EDESTADDRREQ);
 263                 } else {
 264                         afs_get_cell(cell);
 265                 }
 266
 267         }
 268
 269         read_unlock(&afs_cells_lock);
 270         up_read(&afs_cells_sem);
 271         _leave(" = %p", cell);
 272         return cell;
 273 }
 274
 275 #if 0
 276 /*
 277  * try and get a cell record
 278  */
 279 struct afs_cell *afs_get_cell_maybe(struct afs_cell *cell)
 280 {
 281         write_lock(&afs_cells_lock);
 282
 283         if (cell && !list_empty(&cell->link))
 284                 afs_get_cell(cell);
 285         else
 286                 cell = NULL;
 287
 288         write_unlock(&afs_cells_lock);
 289         return cell;
 290 }
 291 #endif  /*  0  */
 292
 293 /*
 294  * destroy a cell record
 295  */
 296 void afs_put_cell(struct afs_cell *cell)
 297 {
 298         if (!cell)
 299                 return;
 300
 301         _enter("%p{%d,%s}", cell, atomic_read(&cell->usage), cell->name);
 302
 303         ASSERTCMP(atomic_read(&cell->usage), >, 0);
 304
 305         /* to prevent a race, the decrement and the dequeue must be effectively
 306          * atomic */
 307         write_lock(&afs_cells_lock);
 308
 309         if (likely(!atomic_dec_and_test(&cell->usage))) {
 310                 write_unlock(&afs_cells_lock);
 311                 _leave("");
 312                 return;
 313         }
 314
 315         ASSERT(list_empty(&cell->servers));
 316         ASSERT(list_empty(&cell->vl_list));
 317
 318         write_unlock(&afs_cells_lock);
 319
 320         wake_up(&afs_cells_freeable_wq);
 321
 322         _leave(" [unused]");
 323 }
 324
 325 /*
 326  * destroy a cell record
 327  * - must be called with the afs_cells_sem write-locked
 328  * - cell->link should have been broken by the caller
 329  */
 330 static void afs_cell_destroy(struct afs_cell *cell)
 331 {
 332         _enter("%p{%d,%s}", cell, atomic_read(&cell->usage), cell->name);
 333
 334         ASSERTCMP(atomic_read(&cell->usage), >=, 0);
 335         ASSERT(list_empty(&cell->link));
 336
 337         /* wait for everyone to stop using the cell */
 338         if (atomic_read(&cell->usage) > 0) {
 339                 DECLARE_WAITQUEUE(myself, current);
 340
 341                 _debug("wait for cell %s", cell->name);
 342                 set_current_state(TASK_UNINTERRUPTIBLE);
 343                 add_wait_queue(&afs_cells_freeable_wq, &myself);
 344
 345                 while (atomic_read(&cell->usage) > 0) {
 346                         schedule();
 347                         set_current_state(TASK_UNINTERRUPTIBLE);
 348                 }
 349
 350                 remove_wait_queue(&afs_cells_freeable_wq, &myself);
 351                 set_current_state(TASK_RUNNING);
 352         }
 353
 354         _debug("cell dead");
 355         ASSERTCMP(atomic_read(&cell->usage), ==, 0);
 356         ASSERT(list_empty(&cell->servers));
 357         ASSERT(list_empty(&cell->vl_list));
 358
 359         afs_proc_cell_remove(cell);
 360
 361         down_write(&afs_proc_cells_sem);
 362         list_del_init(&cell->proc_link);
 363         up_write(&afs_proc_cells_sem);
 364
 365 #ifdef AFS_CACHING_SUPPORT
 366         cachefs_relinquish_cookie(cell->cache, 0);
 367 #endif
 368
 369         key_put(cell->anonymous_key);
 370         kfree(cell);
 371
 372         _leave(" [destroyed]");
 373 }
 374
 375 /*
 376  * purge in-memory cell database on module unload or afs_init() failure
 377  * - the timeout daemon is stopped before calling this
 378  */
 379 void afs_cell_purge(void)
 380 {
 381         struct afs_cell *cell;
 382
 383         _enter("");
 384
 385         afs_put_cell(afs_cell_root);
 386
 387         down_write(&afs_cells_sem);
 388
 389         while (!list_empty(&afs_cells)) {
 390                 cell = NULL;
 391
 392                 /* remove the next cell from the front of the list */
 393                 write_lock(&afs_cells_lock);
 394
 395                 if (!list_empty(&afs_cells)) {
 396                         cell = list_entry(afs_cells.next,
 397                                           struct afs_cell, link);
 398                         list_del_init(&cell->link);
 399                 }
 400
 401                 write_unlock(&afs_cells_lock);
 402
 403                 if (cell) {
 404                         _debug("PURGING CELL %s (%d)",
 405                                cell->name, atomic_read(&cell->usage));
 406
 407                         /* now the cell should be left with no references */
 408                         afs_cell_destroy(cell);
 409                 }
 410         }
 411
 412         up_write(&afs_cells_sem);
 413         _leave("");
 414 }