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         cell = afs_cell_alloc(name, vllist);
 131         if (IS_ERR(cell)) {
 132                 _leave(" = %ld", PTR_ERR(cell));
 133                 return cell;
 134         }
 135
 136         down_write(&afs_cells_sem);
 137
 138         /* add a proc directory for this cell */
 139         ret = afs_proc_cell_setup(cell);
 140         if (ret < 0)
 141                 goto error;
 142
 143 #ifdef AFS_CACHING_SUPPORT
 144         /* put it up for caching */
 145         cachefs_acquire_cookie(afs_cache_netfs.primary_index,
 146                                &afs_vlocation_cache_index_def,
 147                                cell,
 148                                &cell->cache);
 149 #endif
 150
 151         /* add to the cell lists */
 152         write_lock(&afs_cells_lock);
 153         list_add_tail(&cell->link, &afs_cells);
 154         write_unlock(&afs_cells_lock);
 155
 156         down_write(&afs_proc_cells_sem);
 157         list_add_tail(&cell->proc_link, &afs_proc_cells);
 158         up_write(&afs_proc_cells_sem);
 159         up_write(&afs_cells_sem);
 160
 161         _leave(" = %p", cell);
 162         return cell;
 163
 164 error:
 165         up_write(&afs_cells_sem);
 166         key_put(cell->anonymous_key);
 167         kfree(cell);
 168         _leave(" = %d", ret);
 169         return ERR_PTR(ret);
 170 }
 171
 172 /*
 173  * set the root cell information
 174  * - can be called with a module parameter string
 175  * - can be called from a write to /proc/fs/afs/rootcell
 176  */
 177 int afs_cell_init(char *rootcell)
 178 {
 179         struct afs_cell *old_root, *new_root;
 180         char *cp;
 181
 182         _enter("");
 183
 184         if (!rootcell) {
 185                 /* module is loaded with no parameters, or built statically.
 186                  * - in the future we might initialize cell DB here.
 187                  */
 188                 _leave(" = 0 [no root]");
 189                 return 0;
 190         }
 191
 192         cp = strchr(rootcell, ':');
 193         if (!cp) {
 194                 printk(KERN_ERR "kAFS: no VL server IP addresses specified\n");
 195                 _leave(" = -EINVAL");
 196                 return -EINVAL;
 197         }
 198
 199         /* allocate a cell record for the root cell */
 200         *cp++ = 0;
 201         new_root = afs_cell_create(rootcell, cp);
 202         if (IS_ERR(new_root)) {
 203                 _leave(" = %ld", PTR_ERR(new_root));
 204                 return PTR_ERR(new_root);
 205         }
 206
 207         /* install the new cell */
 208         write_lock(&afs_cells_lock);
 209         old_root = afs_cell_root;
 210         afs_cell_root = new_root;
 211         write_unlock(&afs_cells_lock);
 212         afs_put_cell(old_root);
 213
 214         _leave(" = 0");
 215         return 0;
 216 }
 217
 218 /*
 219  * lookup a cell record
 220  */
 221 struct afs_cell *afs_cell_lookup(const char *name, unsigned namesz)
 222 {
 223         struct afs_cell *cell;
 224
 225         _enter("\"%*.*s\",", namesz, namesz, name ? name : "");
 226
 227         down_read(&afs_cells_sem);
 228         read_lock(&afs_cells_lock);
 229
 230         if (name) {
 231                 /* if the cell was named, look for it in the cell record list */
 232                 list_for_each_entry(cell, &afs_cells, link) {
 233                         if (strncmp(cell->name, name, namesz) == 0) {
 234                                 afs_get_cell(cell);
 235                                 goto found;
 236                         }
 237                 }
 238                 cell = ERR_PTR(-ENOENT);
 239         found:
 240                 ;
 241         } else {
 242                 cell = afs_cell_root;
 243                 if (!cell) {
 244                         /* this should not happen unless user tries to mount
 245                          * when root cell is not set. Return an impossibly
 246                          * bizzare errno to alert the user. Things like
 247                          * ENOENT might be "more appropriate" but they happen
 248                          * for other reasons.
 249                          */
 250                         cell = ERR_PTR(-EDESTADDRREQ);
 251                 } else {
 252                         afs_get_cell(cell);
 253                 }
 254
 255         }
 256
 257         read_unlock(&afs_cells_lock);
 258         up_read(&afs_cells_sem);
 259         _leave(" = %p", cell);
 260         return cell;
 261 }
 262
 263 #if 0
 264 /*
 265  * try and get a cell record
 266  */
 267 struct afs_cell *afs_get_cell_maybe(struct afs_cell *cell)
 268 {
 269         write_lock(&afs_cells_lock);
 270
 271         if (cell && !list_empty(&cell->link))
 272                 afs_get_cell(cell);
 273         else
 274                 cell = NULL;
 275
 276         write_unlock(&afs_cells_lock);
 277         return cell;
 278 }
 279 #endif  /*  0  */
 280
 281 /*
 282  * destroy a cell record
 283  */
 284 void afs_put_cell(struct afs_cell *cell)
 285 {
 286         if (!cell)
 287                 return;
 288
 289         _enter("%p{%d,%s}", cell, atomic_read(&cell->usage), cell->name);
 290
 291         ASSERTCMP(atomic_read(&cell->usage), >, 0);
 292
 293         /* to prevent a race, the decrement and the dequeue must be effectively
 294          * atomic */
 295         write_lock(&afs_cells_lock);
 296
 297         if (likely(!atomic_dec_and_test(&cell->usage))) {
 298                 write_unlock(&afs_cells_lock);
 299                 _leave("");
 300                 return;
 301         }
 302
 303         ASSERT(list_empty(&cell->servers));
 304         ASSERT(list_empty(&cell->vl_list));
 305
 306         write_unlock(&afs_cells_lock);
 307
 308         wake_up(&afs_cells_freeable_wq);
 309
 310         _leave(" [unused]");
 311 }
 312
 313 /*
 314  * destroy a cell record
 315  * - must be called with the afs_cells_sem write-locked
 316  * - cell->link should have been broken by the caller
 317  */
 318 static void afs_cell_destroy(struct afs_cell *cell)
 319 {
 320         _enter("%p{%d,%s}", cell, atomic_read(&cell->usage), cell->name);
 321
 322         ASSERTCMP(atomic_read(&cell->usage), >=, 0);
 323         ASSERT(list_empty(&cell->link));
 324
 325         /* wait for everyone to stop using the cell */
 326         if (atomic_read(&cell->usage) > 0) {
 327                 DECLARE_WAITQUEUE(myself, current);
 328
 329                 _debug("wait for cell %s", cell->name);
 330                 set_current_state(TASK_UNINTERRUPTIBLE);
 331                 add_wait_queue(&afs_cells_freeable_wq, &myself);
 332
 333                 while (atomic_read(&cell->usage) > 0) {
 334                         schedule();
 335                         set_current_state(TASK_UNINTERRUPTIBLE);
 336                 }
 337
 338                 remove_wait_queue(&afs_cells_freeable_wq, &myself);
 339                 set_current_state(TASK_RUNNING);
 340         }
 341
 342         _debug("cell dead");
 343         ASSERTCMP(atomic_read(&cell->usage), ==, 0);
 344         ASSERT(list_empty(&cell->servers));
 345         ASSERT(list_empty(&cell->vl_list));
 346
 347         afs_proc_cell_remove(cell);
 348
 349         down_write(&afs_proc_cells_sem);
 350         list_del_init(&cell->proc_link);
 351         up_write(&afs_proc_cells_sem);
 352
 353 #ifdef AFS_CACHING_SUPPORT
 354         cachefs_relinquish_cookie(cell->cache, 0);
 355 #endif
 356
 357         key_put(cell->anonymous_key);
 358         kfree(cell);
 359
 360         _leave(" [destroyed]");
 361 }
 362
 363 /*
 364  * purge in-memory cell database on module unload or afs_init() failure
 365  * - the timeout daemon is stopped before calling this
 366  */
 367 void afs_cell_purge(void)
 368 {
 369         struct afs_cell *cell;
 370
 371         _enter("");
 372
 373         afs_put_cell(afs_cell_root);
 374
 375         down_write(&afs_cells_sem);
 376
 377         while (!list_empty(&afs_cells)) {
 378                 cell = NULL;
 379
 380                 /* remove the next cell from the front of the list */
 381                 write_lock(&afs_cells_lock);
 382
 383                 if (!list_empty(&afs_cells)) {
 384                         cell = list_entry(afs_cells.next,
 385                                           struct afs_cell, link);
 386                         list_del_init(&cell->link);
 387                 }
 388
 389                 write_unlock(&afs_cells_lock);
 390
 391                 if (cell) {
 392                         _debug("PURGING CELL %s (%d)",
 393                                cell->name, atomic_read(&cell->usage));
 394
 395                         /* now the cell should be left with no references */
 396                         afs_cell_destroy(cell);
 397                 }
 398         }
 399
 400         up_write(&afs_cells_sem);
 401         _leave("");
 402 }