fs/afs/volume.c

   1 /* volume.c: AFS volume 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/kernel.h>
  13 #include <linux/module.h>
  14 #include <linux/init.h>
  15 #include <linux/slab.h>
  16 #include <linux/fs.h>
  17 #include <linux/pagemap.h>
  18 #include "volume.h"
  19 #include "vnode.h"
  20 #include "cell.h"
  21 #include "cache.h"
  22 #include "cmservice.h"
  23 #include "fsclient.h"
  24 #include "vlclient.h"
  25 #include "internal.h"
  26
  27 #ifdef __KDEBUG
  28 static const char *afs_voltypes[] = { "R/W", "R/O", "BAK" };
  29 #endif
  30
  31 #ifdef AFS_CACHING_SUPPORT
  32 static cachefs_match_val_t afs_volume_cache_match(void *target,
  33                                                   const void *entry);
  34 static void afs_volume_cache_update(void *source, void *entry);
  35
  36 struct cachefs_index_def afs_volume_cache_index_def = {
  37         .name           = "volume",
  38         .data_size      = sizeof(struct afs_cache_vhash),
  39         .keys[0]        = { CACHEFS_INDEX_KEYS_BIN, 1 },
  40         .keys[1]        = { CACHEFS_INDEX_KEYS_BIN, 1 },
  41         .match          = afs_volume_cache_match,
  42         .update         = afs_volume_cache_update,
  43 };
  44 #endif
  45
  46 /*****************************************************************************/
  47 /*
  48  * lookup a volume by name
  49  * - this can be one of the following:
  50  *      "%[cell:]volume[.]"             R/W volume
  51  *      "#[cell:]volume[.]"             R/O or R/W volume (rwparent=0),
  52  *                                       or R/W (rwparent=1) volume
  53  *      "%[cell:]volume.readonly"       R/O volume
  54  *      "#[cell:]volume.readonly"       R/O volume
  55  *      "%[cell:]volume.backup"         Backup volume
  56  *      "#[cell:]volume.backup"         Backup volume
  57  *
  58  * The cell name is optional, and defaults to the current cell.
  59  *
  60  * See "The Rules of Mount Point Traversal" in Chapter 5 of the AFS SysAdmin
  61  * Guide
  62  * - Rule 1: Explicit type suffix forces access of that type or nothing
  63  *           (no suffix, then use Rule 2 & 3)
  64  * - Rule 2: If parent volume is R/O, then mount R/O volume by preference, R/W
  65  *           if not available
  66  * - Rule 3: If parent volume is R/W, then only mount R/W volume unless
  67  *           explicitly told otherwise
  68  */
  69 int afs_volume_lookup(const char *name, struct afs_cell *cell, int rwpath,
  70                       struct afs_volume **_volume)
  71 {
  72         struct afs_vlocation *vlocation = NULL;
  73         struct afs_volume *volume = NULL;
  74         afs_voltype_t type;
  75         const char *cellname, *volname, *suffix;
  76         char srvtmask;
  77         int force, ret, loop, cellnamesz, volnamesz;
  78
  79         _enter("%s,,%d,", name, rwpath);
  80
  81         if (!name || (name[0] != '%' && name[0] != '#') || !name[1]) {
  82                 printk("kAFS: unparsable volume name\n");
  83                 return -EINVAL;
  84         }
  85
  86         /* determine the type of volume we're looking for */
  87         force = 0;
  88         type = AFSVL_ROVOL;
  89
  90         if (rwpath || name[0] == '%') {
  91                 type = AFSVL_RWVOL;
  92                 force = 1;
  93         }
  94
  95         suffix = strrchr(name, '.');
  96         if (suffix) {
  97                 if (strcmp(suffix, ".readonly") == 0) {
  98                         type = AFSVL_ROVOL;
  99                         force = 1;
 100                 }
 101                 else if (strcmp(suffix, ".backup") == 0) {
 102                         type = AFSVL_BACKVOL;
 103                         force = 1;
 104                 }
 105                 else if (suffix[1] == 0) {
 106                 }
 107                 else {
 108                         suffix = NULL;
 109                 }
 110         }
 111
 112         /* split the cell and volume names */
 113         name++;
 114         volname = strchr(name, ':');
 115         if (volname) {
 116                 cellname = name;
 117                 cellnamesz = volname - name;
 118                 volname++;
 119         }
 120         else {
 121                 volname = name;
 122                 cellname = NULL;
 123                 cellnamesz = 0;
 124         }
 125
 126         volnamesz = suffix ? suffix - volname : strlen(volname);
 127
 128         _debug("CELL:%*.*s [%p] VOLUME:%*.*s SUFFIX:%s TYPE:%d%s",
 129                cellnamesz, cellnamesz, cellname ?: "", cell,
 130                volnamesz, volnamesz, volname, suffix ?: "-",
 131                type,
 132                force ? " FORCE" : "");
 133
 134         /* lookup the cell record */
 135         if (cellname || !cell) {
 136                 ret = afs_cell_lookup(cellname, cellnamesz, &cell);
 137                 if (ret<0) {
 138                         printk("kAFS: unable to lookup cell '%s'\n",
 139                                cellname ?: "");
 140                         goto error;
 141                 }
 142         }
 143         else {
 144                 afs_get_cell(cell);
 145         }
 146
 147         /* lookup the volume location record */
 148         ret = afs_vlocation_lookup(cell, volname, volnamesz, &vlocation);
 149         if (ret < 0)
 150                 goto error;
 151
 152         /* make the final decision on the type we want */
 153         ret = -ENOMEDIUM;
 154         if (force && !(vlocation->vldb.vidmask & (1 << type)))
 155                 goto error;
 156
 157         srvtmask = 0;
 158         for (loop = 0; loop < vlocation->vldb.nservers; loop++)
 159                 srvtmask |= vlocation->vldb.srvtmask[loop];
 160
 161         if (force) {
 162                 if (!(srvtmask & (1 << type)))
 163                         goto error;
 164         }
 165         else if (srvtmask & AFS_VOL_VTM_RO) {
 166                 type = AFSVL_ROVOL;
 167         }
 168         else if (srvtmask & AFS_VOL_VTM_RW) {
 169                 type = AFSVL_RWVOL;
 170         }
 171         else {
 172                 goto error;
 173         }
 174
 175         down_write(&cell->vl_sem);
 176
 177         /* is the volume already active? */
 178         if (vlocation->vols[type]) {
 179                 /* yes - re-use it */
 180                 volume = vlocation->vols[type];
 181                 afs_get_volume(volume);
 182                 goto success;
 183         }
 184
 185         /* create a new volume record */
 186         _debug("creating new volume record");
 187
 188         ret = -ENOMEM;
 189         volume = kmalloc(sizeof(struct afs_volume), GFP_KERNEL);
 190         if (!volume)
 191                 goto error_up;
 192
 193         memset(volume, 0, sizeof(struct afs_volume));
 194         atomic_set(&volume->usage, 1);
 195         volume->type            = type;
 196         volume->type_force      = force;
 197         volume->cell            = cell;
 198         volume->vid             = vlocation->vldb.vid[type];
 199
 200         init_rwsem(&volume->server_sem);
 201
 202         /* look up all the applicable server records */
 203         for (loop = 0; loop < 8; loop++) {
 204                 if (vlocation->vldb.srvtmask[loop] & (1 << volume->type)) {
 205                         ret = afs_server_lookup(
 206                                 volume->cell,
 207                                 &vlocation->vldb.servers[loop],
 208                                 &volume->servers[volume->nservers]);
 209                         if (ret < 0)
 210                                 goto error_discard;
 211
 212                         volume->nservers++;
 213                 }
 214         }
 215
 216         /* attach the cache and volume location */
 217 #ifdef AFS_CACHING_SUPPORT
 218         cachefs_acquire_cookie(vlocation->cache,
 219                                &afs_vnode_cache_index_def,
 220                                volume,
 221                                &volume->cache);
 222 #endif
 223
 224         afs_get_vlocation(vlocation);
 225         volume->vlocation = vlocation;
 226
 227         vlocation->vols[type] = volume;
 228
 229  success:
 230         _debug("kAFS selected %s volume %08x",
 231                afs_voltypes[volume->type], volume->vid);
 232         *_volume = volume;
 233         ret = 0;
 234
 235         /* clean up */
 236  error_up:
 237         up_write(&cell->vl_sem);
 238  error:
 239         afs_put_vlocation(vlocation);
 240         afs_put_cell(cell);
 241
 242         _leave(" = %d (%p)", ret, volume);
 243         return ret;
 244
 245  error_discard:
 246         up_write(&cell->vl_sem);
 247
 248         for (loop = volume->nservers - 1; loop >= 0; loop--)
 249                 afs_put_server(volume->servers[loop]);
 250
 251         kfree(volume);
 252         goto error;
 253 } /* end afs_volume_lookup() */
 254
 255 /*****************************************************************************/
 256 /*
 257  * destroy a volume record
 258  */
 259 void afs_put_volume(struct afs_volume *volume)
 260 {
 261         struct afs_vlocation *vlocation;
 262         int loop;
 263
 264         if (!volume)
 265                 return;
 266
 267         _enter("%p", volume);
 268
 269         vlocation = volume->vlocation;
 270
 271         /* sanity check */
 272         BUG_ON(atomic_read(&volume->usage) <= 0);
 273
 274         /* to prevent a race, the decrement and the dequeue must be effectively
 275          * atomic */
 276         down_write(&vlocation->cell->vl_sem);
 277
 278         if (likely(!atomic_dec_and_test(&volume->usage))) {
 279                 up_write(&vlocation->cell->vl_sem);
 280                 _leave("");
 281                 return;
 282         }
 283
 284         vlocation->vols[volume->type] = NULL;
 285
 286         up_write(&vlocation->cell->vl_sem);
 287
 288         /* finish cleaning up the volume */
 289 #ifdef AFS_CACHING_SUPPORT
 290         cachefs_relinquish_cookie(volume->cache, 0);
 291 #endif
 292         afs_put_vlocation(vlocation);
 293
 294         for (loop = volume->nservers - 1; loop >= 0; loop--)
 295                 afs_put_server(volume->servers[loop]);
 296
 297         kfree(volume);
 298
 299         _leave(" [destroyed]");
 300 } /* end afs_put_volume() */
 301
 302 /*****************************************************************************/
 303 /*
 304  * pick a server to use to try accessing this volume
 305  * - returns with an elevated usage count on the server chosen
 306  */
 307 int afs_volume_pick_fileserver(struct afs_volume *volume,
 308                                struct afs_server **_server)
 309 {
 310         struct afs_server *server;
 311         int ret, state, loop;
 312
 313         _enter("%s", volume->vlocation->vldb.name);
 314
 315         down_read(&volume->server_sem);
 316
 317         /* handle the no-server case */
 318         if (volume->nservers == 0) {
 319                 ret = volume->rjservers ? -ENOMEDIUM : -ESTALE;
 320                 up_read(&volume->server_sem);
 321                 _leave(" = %d [no servers]", ret);
 322                 return ret;
 323         }
 324
 325         /* basically, just search the list for the first live server and use
 326          * that */
 327         ret = 0;
 328         for (loop = 0; loop < volume->nservers; loop++) {
 329                 server = volume->servers[loop];
 330                 state = server->fs_state;
 331
 332                 switch (state) {
 333                         /* found an apparently healthy server */
 334                 case 0:
 335                         afs_get_server(server);
 336                         up_read(&volume->server_sem);
 337                         *_server = server;
 338                         _leave(" = 0 (picked %08x)",
 339                                ntohl(server->addr.s_addr));
 340                         return 0;
 341
 342                 case -ENETUNREACH:
 343                         if (ret == 0)
 344                                 ret = state;
 345                         break;
 346
 347                 case -EHOSTUNREACH:
 348                         if (ret == 0 ||
 349                             ret == -ENETUNREACH)
 350                                 ret = state;
 351                         break;
 352
 353                 case -ECONNREFUSED:
 354                         if (ret == 0 ||
 355                             ret == -ENETUNREACH ||
 356                             ret == -EHOSTUNREACH)
 357                                 ret = state;
 358                         break;
 359
 360                 default:
 361                 case -EREMOTEIO:
 362                         if (ret == 0 ||
 363                             ret == -ENETUNREACH ||
 364                             ret == -EHOSTUNREACH ||
 365                             ret == -ECONNREFUSED)
 366                                 ret = state;
 367                         break;
 368                 }
 369         }
 370
 371         /* no available servers
 372          * - TODO: handle the no active servers case better
 373          */
 374         up_read(&volume->server_sem);
 375         _leave(" = %d", ret);
 376         return ret;
 377 } /* end afs_volume_pick_fileserver() */
 378
 379 /*****************************************************************************/
 380 /*
 381  * release a server after use
 382  * - releases the ref on the server struct that was acquired by picking
 383  * - records result of using a particular server to access a volume
 384  * - return 0 to try again, 1 if okay or to issue error
 385  */
 386 int afs_volume_release_fileserver(struct afs_volume *volume,
 387                                   struct afs_server *server,
 388                                   int result)
 389 {
 390         unsigned loop;
 391
 392         _enter("%s,%08x,%d",
 393                volume->vlocation->vldb.name, ntohl(server->addr.s_addr),
 394                result);
 395
 396         switch (result) {
 397                 /* success */
 398         case 0:
 399                 server->fs_act_jif = jiffies;
 400                 break;
 401
 402                 /* the fileserver denied all knowledge of the volume */
 403         case -ENOMEDIUM:
 404                 server->fs_act_jif = jiffies;
 405                 down_write(&volume->server_sem);
 406
 407                 /* first, find where the server is in the active list (if it
 408                  * is) */
 409                 for (loop = 0; loop < volume->nservers; loop++)
 410                         if (volume->servers[loop] == server)
 411                                 goto present;
 412
 413                 /* no longer there - may have been discarded by another op */
 414                 goto try_next_server_upw;
 415
 416         present:
 417                 volume->nservers--;
 418                 memmove(&volume->servers[loop],
 419                         &volume->servers[loop + 1],
 420                         sizeof(volume->servers[loop]) *
 421                         (volume->nservers - loop));
 422                 volume->servers[volume->nservers] = NULL;
 423                 afs_put_server(server);
 424                 volume->rjservers++;
 425
 426                 if (volume->nservers > 0)
 427                         /* another server might acknowledge its existence */
 428                         goto try_next_server_upw;
 429
 430                 /* handle the case where all the fileservers have rejected the
 431                  * volume
 432                  * - TODO: try asking the fileservers for volume information
 433                  * - TODO: contact the VL server again to see if the volume is
 434                  *         no longer registered
 435                  */
 436                 up_write(&volume->server_sem);
 437                 afs_put_server(server);
 438                 _leave(" [completely rejected]");
 439                 return 1;
 440
 441                 /* problem reaching the server */
 442         case -ENETUNREACH:
 443         case -EHOSTUNREACH:
 444         case -ECONNREFUSED:
 445         case -ETIMEDOUT:
 446         case -EREMOTEIO:
 447                 /* mark the server as dead
 448                  * TODO: vary dead timeout depending on error
 449                  */
 450                 spin_lock(&server->fs_lock);
 451                 if (!server->fs_state) {
 452                         server->fs_dead_jif = jiffies + HZ * 10;
 453                         server->fs_state = result;
 454                         printk("kAFS: SERVER DEAD state=%d\n", result);
 455                 }
 456                 spin_unlock(&server->fs_lock);
 457                 goto try_next_server;
 458
 459                 /* miscellaneous error */
 460         default:
 461                 server->fs_act_jif = jiffies;
 462         case -ENOMEM:
 463         case -ENONET:
 464                 break;
 465         }
 466
 467         /* tell the caller to accept the result */
 468         afs_put_server(server);
 469         _leave("");
 470         return 1;
 471
 472         /* tell the caller to loop around and try the next server */
 473  try_next_server_upw:
 474         up_write(&volume->server_sem);
 475  try_next_server:
 476         afs_put_server(server);
 477         _leave(" [try next server]");
 478         return 0;
 479
 480 } /* end afs_volume_release_fileserver() */
 481
 482 /*****************************************************************************/
 483 /*
 484  * match a volume hash record stored in the cache
 485  */
 486 #ifdef AFS_CACHING_SUPPORT
 487 static cachefs_match_val_t afs_volume_cache_match(void *target,
 488                                                   const void *entry)
 489 {
 490         const struct afs_cache_vhash *vhash = entry;
 491         struct afs_volume *volume = target;
 492
 493         _enter("{%u},{%u}", volume->type, vhash->vtype);
 494
 495         if (volume->type == vhash->vtype) {
 496                 _leave(" = SUCCESS");
 497                 return CACHEFS_MATCH_SUCCESS;
 498         }
 499
 500         _leave(" = FAILED");
 501         return CACHEFS_MATCH_FAILED;
 502 } /* end afs_volume_cache_match() */
 503 #endif
 504
 505 /*****************************************************************************/
 506 /*
 507  * update a volume hash record stored in the cache
 508  */
 509 #ifdef AFS_CACHING_SUPPORT
 510 static void afs_volume_cache_update(void *source, void *entry)
 511 {
 512         struct afs_cache_vhash *vhash = entry;
 513         struct afs_volume *volume = source;
 514
 515         _enter("");
 516
 517         vhash->vtype = volume->type;
 518
 519 } /* end afs_volume_cache_update() */
 520 #endif