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