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 = kzalloc(sizeof(struct afs_volume), GFP_KERNEL);
 190         if (!volume)
 191                 goto error_up;
 192
 193         atomic_set(&volume->usage, 1);
 194         volume->type            = type;
 195         volume->type_force      = force;
 196         volume->cell            = cell;
 197         volume->vid             = vlocation->vldb.vid[type];
 198
 199         init_rwsem(&volume->server_sem);
 200
 201         /* look up all the applicable server records */
 202         for (loop = 0; loop < 8; loop++) {
 203                 if (vlocation->vldb.srvtmask[loop] & (1 << volume->type)) {
 204                         ret = afs_server_lookup(
 205                                 volume->cell,
 206                                 &vlocation->vldb.servers[loop],
 207                                 &volume->servers[volume->nservers]);
 208                         if (ret < 0)
 209                                 goto error_discard;
 210
 211                         volume->nservers++;
 212                 }
 213         }
 214
 215         /* attach the cache and volume location */
 216 #ifdef AFS_CACHING_SUPPORT
 217         cachefs_acquire_cookie(vlocation->cache,
 218                                &afs_vnode_cache_index_def,
 219                                volume,
 220                                &volume->cache);
 221 #endif
 222
 223         afs_get_vlocation(vlocation);
 224         volume->vlocation = vlocation;
 225
 226         vlocation->vols[type] = volume;
 227
 228  success:
 229         _debug("kAFS selected %s volume %08x",
 230                afs_voltypes[volume->type], volume->vid);
 231         *_volume = volume;
 232         ret = 0;
 233
 234         /* clean up */
 235  error_up:
 236         up_write(&cell->vl_sem);
 237  error:
 238         afs_put_vlocation(vlocation);
 239         afs_put_cell(cell);
 240
 241         _leave(" = %d (%p)", ret, volume);
 242         return ret;
 243
 244  error_discard:
 245         up_write(&cell->vl_sem);
 246
 247         for (loop = volume->nservers - 1; loop >= 0; loop--)
 248                 afs_put_server(volume->servers[loop]);
 249
 250         kfree(volume);
 251         goto error;
 252 } /* end afs_volume_lookup() */
 253
 254 /*****************************************************************************/
 255 /*
 256  * destroy a volume record
 257  */
 258 void afs_put_volume(struct afs_volume *volume)
 259 {
 260         struct afs_vlocation *vlocation;
 261         int loop;
 262
 263         if (!volume)
 264                 return;
 265
 266         _enter("%p", volume);
 267
 268         vlocation = volume->vlocation;
 269
 270         /* sanity check */
 271         BUG_ON(atomic_read(&volume->usage) <= 0);
 272
 273         /* to prevent a race, the decrement and the dequeue must be effectively
 274          * atomic */
 275         down_write(&vlocation->cell->vl_sem);
 276
 277         if (likely(!atomic_dec_and_test(&volume->usage))) {
 278                 up_write(&vlocation->cell->vl_sem);
 279                 _leave("");
 280                 return;
 281         }
 282
 283         vlocation->vols[volume->type] = NULL;
 284
 285         up_write(&vlocation->cell->vl_sem);
 286
 287         /* finish cleaning up the volume */
 288 #ifdef AFS_CACHING_SUPPORT
 289         cachefs_relinquish_cookie(volume->cache, 0);
 290 #endif
 291         afs_put_vlocation(vlocation);
 292
 293         for (loop = volume->nservers - 1; loop >= 0; loop--)
 294                 afs_put_server(volume->servers[loop]);
 295
 296         kfree(volume);
 297
 298         _leave(" [destroyed]");
 299 } /* end afs_put_volume() */
 300
 301 /*****************************************************************************/
 302 /*
 303  * pick a server to use to try accessing this volume
 304  * - returns with an elevated usage count on the server chosen
 305  */
 306 int afs_volume_pick_fileserver(struct afs_volume *volume,
 307                                struct afs_server **_server)
 308 {
 309         struct afs_server *server;
 310         int ret, state, loop;
 311
 312         _enter("%s", volume->vlocation->vldb.name);
 313
 314         down_read(&volume->server_sem);
 315
 316         /* handle the no-server case */
 317         if (volume->nservers == 0) {
 318                 ret = volume->rjservers ? -ENOMEDIUM : -ESTALE;
 319                 up_read(&volume->server_sem);
 320                 _leave(" = %d [no servers]", ret);
 321                 return ret;
 322         }
 323
 324         /* basically, just search the list for the first live server and use
 325          * that */
 326         ret = 0;
 327         for (loop = 0; loop < volume->nservers; loop++) {
 328                 server = volume->servers[loop];
 329                 state = server->fs_state;
 330
 331                 switch (state) {
 332                         /* found an apparently healthy server */
 333                 case 0:
 334                         afs_get_server(server);
 335                         up_read(&volume->server_sem);
 336                         *_server = server;
 337                         _leave(" = 0 (picked %08x)",
 338                                ntohl(server->addr.s_addr));
 339                         return 0;
 340
 341                 case -ENETUNREACH:
 342                         if (ret == 0)
 343                                 ret = state;
 344                         break;
 345
 346                 case -EHOSTUNREACH:
 347                         if (ret == 0 ||
 348                             ret == -ENETUNREACH)
 349                                 ret = state;
 350                         break;
 351
 352                 case -ECONNREFUSED:
 353                         if (ret == 0 ||
 354                             ret == -ENETUNREACH ||
 355                             ret == -EHOSTUNREACH)
 356                                 ret = state;
 357                         break;
 358
 359                 default:
 360                 case -EREMOTEIO:
 361                         if (ret == 0 ||
 362                             ret == -ENETUNREACH ||
 363                             ret == -EHOSTUNREACH ||
 364                             ret == -ECONNREFUSED)
 365                                 ret = state;
 366                         break;
 367                 }
 368         }
 369
 370         /* no available servers
 371          * - TODO: handle the no active servers case better
 372          */
 373         up_read(&volume->server_sem);
 374         _leave(" = %d", ret);
 375         return ret;
 376 } /* end afs_volume_pick_fileserver() */
 377
 378 /*****************************************************************************/
 379 /*
 380  * release a server after use
 381  * - releases the ref on the server struct that was acquired by picking
 382  * - records result of using a particular server to access a volume
 383  * - return 0 to try again, 1 if okay or to issue error
 384  */
 385 int afs_volume_release_fileserver(struct afs_volume *volume,
 386                                   struct afs_server *server,
 387                                   int result)
 388 {
 389         unsigned loop;
 390
 391         _enter("%s,%08x,%d",
 392                volume->vlocation->vldb.name, ntohl(server->addr.s_addr),
 393                result);
 394
 395         switch (result) {
 396                 /* success */
 397         case 0:
 398                 server->fs_act_jif = jiffies;
 399                 break;
 400
 401                 /* the fileserver denied all knowledge of the volume */
 402         case -ENOMEDIUM:
 403                 server->fs_act_jif = jiffies;
 404                 down_write(&volume->server_sem);
 405
 406                 /* first, find where the server is in the active list (if it
 407                  * is) */
 408                 for (loop = 0; loop < volume->nservers; loop++)
 409                         if (volume->servers[loop] == server)
 410                                 goto present;
 411
 412                 /* no longer there - may have been discarded by another op */
 413                 goto try_next_server_upw;
 414
 415         present:
 416                 volume->nservers--;
 417                 memmove(&volume->servers[loop],
 418                         &volume->servers[loop + 1],
 419                         sizeof(volume->servers[loop]) *
 420                         (volume->nservers - loop));
 421                 volume->servers[volume->nservers] = NULL;
 422                 afs_put_server(server);
 423                 volume->rjservers++;
 424
 425                 if (volume->nservers > 0)
 426                         /* another server might acknowledge its existence */
 427                         goto try_next_server_upw;
 428
 429                 /* handle the case where all the fileservers have rejected the
 430                  * volume
 431                  * - TODO: try asking the fileservers for volume information
 432                  * - TODO: contact the VL server again to see if the volume is
 433                  *         no longer registered
 434                  */
 435                 up_write(&volume->server_sem);
 436                 afs_put_server(server);
 437                 _leave(" [completely rejected]");
 438                 return 1;
 439
 440                 /* problem reaching the server */
 441         case -ENETUNREACH:
 442         case -EHOSTUNREACH:
 443         case -ECONNREFUSED:
 444         case -ETIMEDOUT:
 445         case -EREMOTEIO:
 446                 /* mark the server as dead
 447                  * TODO: vary dead timeout depending on error
 448                  */
 449                 spin_lock(&server->fs_lock);
 450                 if (!server->fs_state) {
 451                         server->fs_dead_jif = jiffies + HZ * 10;
 452                         server->fs_state = result;
 453                         printk("kAFS: SERVER DEAD state=%d\n", result);
 454                 }
 455                 spin_unlock(&server->fs_lock);
 456                 goto try_next_server;
 457
 458                 /* miscellaneous error */
 459         default:
 460                 server->fs_act_jif = jiffies;
 461         case -ENOMEM:
 462         case -ENONET:
 463                 break;
 464         }
 465
 466         /* tell the caller to accept the result */
 467         afs_put_server(server);
 468         _leave("");
 469         return 1;
 470
 471         /* tell the caller to loop around and try the next server */
 472  try_next_server_upw:
 473         up_write(&volume->server_sem);
 474  try_next_server:
 475         afs_put_server(server);
 476         _leave(" [try next server]");
 477         return 0;
 478
 479 } /* end afs_volume_release_fileserver() */
 480
 481 /*****************************************************************************/
 482 /*
 483  * match a volume hash record stored in the cache
 484  */
 485 #ifdef AFS_CACHING_SUPPORT
 486 static cachefs_match_val_t afs_volume_cache_match(void *target,
 487                                                   const void *entry)
 488 {
 489         const struct afs_cache_vhash *vhash = entry;
 490         struct afs_volume *volume = target;
 491
 492         _enter("{%u},{%u}", volume->type, vhash->vtype);
 493
 494         if (volume->type == vhash->vtype) {
 495                 _leave(" = SUCCESS");
 496                 return CACHEFS_MATCH_SUCCESS;
 497         }
 498
 499         _leave(" = FAILED");
 500         return CACHEFS_MATCH_FAILED;
 501 } /* end afs_volume_cache_match() */
 502 #endif
 503
 504 /*****************************************************************************/
 505 /*
 506  * update a volume hash record stored in the cache
 507  */
 508 #ifdef AFS_CACHING_SUPPORT
 509 static void afs_volume_cache_update(void *source, void *entry)
 510 {
 511         struct afs_cache_vhash *vhash = entry;
 512         struct afs_volume *volume = source;
 513
 514         _enter("");
 515
 516         vhash->vtype = volume->type;
 517
 518 } /* end afs_volume_cache_update() */
 519 #endif