fs/afs/volume.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /* AFS volume management
   3  *
   4  * Copyright (C) 2002, 2007 Red Hat, Inc. All Rights Reserved.
   5  * Written by David Howells (dhowells@redhat.com)
   6  */
   7
   8 #include <linux/kernel.h>
   9 #include <linux/slab.h>
  10 #include "internal.h"
  11
  12 static unsigned __read_mostly afs_volume_record_life = 60 * 60;
  13
  14 static void afs_destroy_volume(struct work_struct *work);
  15
  16 /*
  17  * Insert a volume into a cell.  If there's an existing volume record, that is
  18  * returned instead with a ref held.
  19  */
  20 static struct afs_volume *afs_insert_volume_into_cell(struct afs_cell *cell,
  21                                                       struct afs_volume *volume)
  22 {
  23         struct afs_volume *p;
  24         struct rb_node *parent = NULL, **pp;
  25
  26         write_seqlock(&cell->volume_lock);
  27
  28         pp = &cell->volumes.rb_node;
  29         while (*pp) {
  30                 parent = *pp;
  31                 p = rb_entry(parent, struct afs_volume, cell_node);
  32                 if (p->vid < volume->vid) {
  33                         pp = &(*pp)->rb_left;
  34                 } else if (p->vid > volume->vid) {
  35                         pp = &(*pp)->rb_right;
  36                 } else {
  37                         if (afs_try_get_volume(p, afs_volume_trace_get_cell_insert)) {
  38                                 volume = p;
  39                                 goto found;
  40                         }
  41
  42                         set_bit(AFS_VOLUME_RM_TREE, &volume->flags);
  43                         rb_replace_node_rcu(&p->cell_node, &volume->cell_node, &cell->volumes);
  44                 }
  45         }
  46
  47         rb_link_node_rcu(&volume->cell_node, parent, pp);
  48         rb_insert_color(&volume->cell_node, &cell->volumes);
  49         hlist_add_head_rcu(&volume->proc_link, &cell->proc_volumes);
  50
  51 found:
  52         write_sequnlock(&cell->volume_lock);
  53         return volume;
  54
  55 }
  56
  57 static void afs_remove_volume_from_cell(struct afs_volume *volume)
  58 {
  59         struct afs_cell *cell = volume->cell;
  60
  61         if (!hlist_unhashed(&volume->proc_link)) {
  62                 trace_afs_volume(volume->vid, refcount_read(&cell->ref),
  63                                  afs_volume_trace_remove);
  64                 write_seqlock(&cell->volume_lock);
  65                 hlist_del_rcu(&volume->proc_link);
  66                 if (!test_and_set_bit(AFS_VOLUME_RM_TREE, &volume->flags))
  67                         rb_erase(&volume->cell_node, &cell->volumes);
  68                 write_sequnlock(&cell->volume_lock);
  69         }
  70 }
  71
  72 /*
  73  * Allocate a volume record and load it up from a vldb record.
  74  */
  75 static struct afs_volume *afs_alloc_volume(struct afs_fs_context *params,
  76                                            struct afs_vldb_entry *vldb,
  77                                            struct afs_server_list **_slist)
  78 {
  79         struct afs_server_list *slist;
  80         struct afs_volume *volume;
  81         int ret = -ENOMEM, i;
  82
  83         volume = kzalloc(sizeof(struct afs_volume), GFP_KERNEL);
  84         if (!volume)
  85                 goto error_0;
  86
  87         volume->vid             = vldb->vid[params->type];
  88         volume->update_at       = ktime_get_real_seconds() + afs_volume_record_life;
  89         volume->cell            = afs_get_cell(params->cell, afs_cell_trace_get_vol);
  90         volume->type            = params->type;
  91         volume->type_force      = params->force;
  92         volume->name_len        = vldb->name_len;
  93         volume->creation_time   = TIME64_MIN;
  94         volume->update_time     = TIME64_MIN;
  95
  96         refcount_set(&volume->ref, 1);
  97         INIT_HLIST_NODE(&volume->proc_link);
  98         INIT_WORK(&volume->destructor, afs_destroy_volume);
  99         rwlock_init(&volume->servers_lock);
 100         mutex_init(&volume->volsync_lock);
 101         mutex_init(&volume->cb_check_lock);
 102         rwlock_init(&volume->cb_v_break_lock);
 103         INIT_LIST_HEAD(&volume->open_mmaps);
 104         init_rwsem(&volume->open_mmaps_lock);
 105         memcpy(volume->name, vldb->name, vldb->name_len + 1);
 106
 107         for (i = 0; i < AFS_MAXTYPES; i++)
 108                 volume->vids[i] = vldb->vid[i];
 109
 110         slist = afs_alloc_server_list(volume, params->key, vldb);
 111         if (IS_ERR(slist)) {
 112                 ret = PTR_ERR(slist);
 113                 goto error_1;
 114         }
 115
 116         *_slist = slist;
 117         rcu_assign_pointer(volume->servers, slist);
 118         trace_afs_volume(volume->vid, 1, afs_volume_trace_alloc);
 119         return volume;
 120
 121 error_1:
 122         afs_put_cell(volume->cell, afs_cell_trace_put_vol);
 123         kfree(volume);
 124 error_0:
 125         return ERR_PTR(ret);
 126 }
 127
 128 /*
 129  * Look up or allocate a volume record.
 130  */
 131 static struct afs_volume *afs_lookup_volume(struct afs_fs_context *params,
 132                                             struct afs_vldb_entry *vldb)
 133 {
 134         struct afs_server_list *slist;
 135         struct afs_volume *candidate, *volume;
 136
 137         candidate = afs_alloc_volume(params, vldb, &slist);
 138         if (IS_ERR(candidate))
 139                 return candidate;
 140
 141         volume = afs_insert_volume_into_cell(params->cell, candidate);
 142         if (volume == candidate)
 143                 afs_attach_volume_to_servers(volume, slist);
 144         else
 145                 afs_put_volume(candidate, afs_volume_trace_put_cell_dup);
 146         return volume;
 147 }
 148
 149 /*
 150  * Look up a VLDB record for a volume.
 151  */
 152 static struct afs_vldb_entry *afs_vl_lookup_vldb(struct afs_cell *cell,
 153                                                  struct key *key,
 154                                                  const char *volname,
 155                                                  size_t volnamesz)
 156 {
 157         struct afs_vldb_entry *vldb = ERR_PTR(-EDESTADDRREQ);
 158         struct afs_vl_cursor vc;
 159         int ret;
 160
 161         if (!afs_begin_vlserver_operation(&vc, cell, key))
 162                 return ERR_PTR(-ERESTARTSYS);
 163
 164         while (afs_select_vlserver(&vc)) {
 165                 vldb = afs_vl_get_entry_by_name_u(&vc, volname, volnamesz);
 166         }
 167
 168         ret = afs_end_vlserver_operation(&vc);
 169         return ret < 0 ? ERR_PTR(ret) : vldb;
 170 }
 171
 172 /*
 173  * Look up a volume in the VL server and create a candidate volume record for
 174  * it.
 175  *
 176  * The volume name can be one of the following:
 177  *      "%[cell:]volume[.]"             R/W volume
 178  *      "#[cell:]volume[.]"             R/O or R/W volume (rwparent=0),
 179  *                                       or R/W (rwparent=1) volume
 180  *      "%[cell:]volume.readonly"       R/O volume
 181  *      "#[cell:]volume.readonly"       R/O volume
 182  *      "%[cell:]volume.backup"         Backup volume
 183  *      "#[cell:]volume.backup"         Backup volume
 184  *
 185  * The cell name is optional, and defaults to the current cell.
 186  *
 187  * See "The Rules of Mount Point Traversal" in Chapter 5 of the AFS SysAdmin
 188  * Guide
 189  * - Rule 1: Explicit type suffix forces access of that type or nothing
 190  *           (no suffix, then use Rule 2 & 3)
 191  * - Rule 2: If parent volume is R/O, then mount R/O volume by preference, R/W
 192  *           if not available
 193  * - Rule 3: If parent volume is R/W, then only mount R/W volume unless
 194  *           explicitly told otherwise
 195  */
 196 struct afs_volume *afs_create_volume(struct afs_fs_context *params)
 197 {
 198         struct afs_vldb_entry *vldb;
 199         struct afs_volume *volume;
 200         unsigned long type_mask = 1UL << params->type;
 201
 202         vldb = afs_vl_lookup_vldb(params->cell, params->key,
 203                                   params->volname, params->volnamesz);
 204         if (IS_ERR(vldb))
 205                 return ERR_CAST(vldb);
 206
 207         if (test_bit(AFS_VLDB_QUERY_ERROR, &vldb->flags)) {
 208                 volume = ERR_PTR(vldb->error);
 209                 goto error;
 210         }
 211
 212         /* Make the final decision on the type we want */
 213         volume = ERR_PTR(-ENOMEDIUM);
 214         if (params->force) {
 215                 if (!(vldb->flags & type_mask))
 216                         goto error;
 217         } else if (test_bit(AFS_VLDB_HAS_RO, &vldb->flags)) {
 218                 params->type = AFSVL_ROVOL;
 219         } else if (test_bit(AFS_VLDB_HAS_RW, &vldb->flags)) {
 220                 params->type = AFSVL_RWVOL;
 221         } else {
 222                 goto error;
 223         }
 224
 225         volume = afs_lookup_volume(params, vldb);
 226
 227 error:
 228         kfree(vldb);
 229         return volume;
 230 }
 231
 232 /*
 233  * Destroy a volume record
 234  */
 235 static void afs_destroy_volume(struct work_struct *work)
 236 {
 237         struct afs_volume *volume = container_of(work, struct afs_volume, destructor);
 238         struct afs_server_list *slist = rcu_access_pointer(volume->servers);
 239
 240         _enter("%p", volume);
 241
 242 #ifdef CONFIG_AFS_FSCACHE
 243         ASSERTCMP(volume->cache, ==, NULL);
 244 #endif
 245
 246         afs_detach_volume_from_servers(volume, slist);
 247         afs_remove_volume_from_cell(volume);
 248         afs_put_serverlist(volume->cell->net, slist);
 249         afs_put_cell(volume->cell, afs_cell_trace_put_vol);
 250         trace_afs_volume(volume->vid, refcount_read(&volume->ref),
 251                          afs_volume_trace_free);
 252         kfree_rcu(volume, rcu);
 253
 254         _leave(" [destroyed]");
 255 }
 256
 257 /*
 258  * Try to get a reference on a volume record.
 259  */
 260 bool afs_try_get_volume(struct afs_volume *volume, enum afs_volume_trace reason)
 261 {
 262         int r;
 263
 264         if (__refcount_inc_not_zero(&volume->ref, &r)) {
 265                 trace_afs_volume(volume->vid, r + 1, reason);
 266                 return true;
 267         }
 268         return false;
 269 }
 270
 271 /*
 272  * Get a reference on a volume record.
 273  */
 274 struct afs_volume *afs_get_volume(struct afs_volume *volume,
 275                                   enum afs_volume_trace reason)
 276 {
 277         if (volume) {
 278                 int r;
 279
 280                 __refcount_inc(&volume->ref, &r);
 281                 trace_afs_volume(volume->vid, r + 1, reason);
 282         }
 283         return volume;
 284 }
 285
 286
 287 /*
 288  * Drop a reference on a volume record.
 289  */
 290 void afs_put_volume(struct afs_volume *volume, enum afs_volume_trace reason)
 291 {
 292         if (volume) {
 293                 afs_volid_t vid = volume->vid;
 294                 bool zero;
 295                 int r;
 296
 297                 zero = __refcount_dec_and_test(&volume->ref, &r);
 298                 trace_afs_volume(vid, r - 1, reason);
 299                 if (zero)
 300                         schedule_work(&volume->destructor);
 301         }
 302 }
 303
 304 /*
 305  * Activate a volume.
 306  */
 307 int afs_activate_volume(struct afs_volume *volume)
 308 {
 309 #ifdef CONFIG_AFS_FSCACHE
 310         struct fscache_volume *vcookie;
 311         char *name;
 312
 313         name = kasprintf(GFP_KERNEL, "afs,%s,%llx",
 314                          volume->cell->name, volume->vid);
 315         if (!name)
 316                 return -ENOMEM;
 317
 318         vcookie = fscache_acquire_volume(name, NULL, NULL, 0);
 319         if (IS_ERR(vcookie)) {
 320                 if (vcookie != ERR_PTR(-EBUSY)) {
 321                         kfree(name);
 322                         return PTR_ERR(vcookie);
 323                 }
 324                 pr_err("AFS: Cache volume key already in use (%s)\n", name);
 325                 vcookie = NULL;
 326         }
 327         volume->cache = vcookie;
 328         kfree(name);
 329 #endif
 330         return 0;
 331 }
 332
 333 /*
 334  * Deactivate a volume.
 335  */
 336 void afs_deactivate_volume(struct afs_volume *volume)
 337 {
 338         _enter("%s", volume->name);
 339
 340 #ifdef CONFIG_AFS_FSCACHE
 341         fscache_relinquish_volume(volume->cache, NULL,
 342                                   test_bit(AFS_VOLUME_DELETED, &volume->flags));
 343         volume->cache = NULL;
 344 #endif
 345
 346         _leave("");
 347 }
 348
 349 /*
 350  * Query the VL service to update the volume status.
 351  */
 352 static int afs_update_volume_status(struct afs_volume *volume, struct key *key)
 353 {
 354         struct afs_server_list *new, *old, *discard;
 355         struct afs_vldb_entry *vldb;
 356         char idbuf[24];
 357         int ret, idsz;
 358
 359         _enter("");
 360
 361         /* We look up an ID by passing it as a decimal string in the
 362          * operation's name parameter.
 363          */
 364         idsz = snprintf(idbuf, sizeof(idbuf), "%llu", volume->vid);
 365
 366         vldb = afs_vl_lookup_vldb(volume->cell, key, idbuf, idsz);
 367         if (IS_ERR(vldb)) {
 368                 ret = PTR_ERR(vldb);
 369                 goto error;
 370         }
 371
 372         /* See if the volume got renamed. */
 373         if (vldb->name_len != volume->name_len ||
 374             memcmp(vldb->name, volume->name, vldb->name_len) != 0) {
 375                 /* TODO: Use RCU'd string. */
 376                 memcpy(volume->name, vldb->name, AFS_MAXVOLNAME);
 377                 volume->name_len = vldb->name_len;
 378         }
 379
 380         /* See if the volume's server list got updated. */
 381         new = afs_alloc_server_list(volume, key, vldb);
 382         if (IS_ERR(new)) {
 383                 ret = PTR_ERR(new);
 384                 goto error_vldb;
 385         }
 386
 387         write_lock(&volume->servers_lock);
 388
 389         discard = new;
 390         old = rcu_dereference_protected(volume->servers,
 391                                         lockdep_is_held(&volume->servers_lock));
 392         if (afs_annotate_server_list(new, old)) {
 393                 new->seq = volume->servers_seq + 1;
 394                 rcu_assign_pointer(volume->servers, new);
 395                 smp_wmb();
 396                 volume->servers_seq++;
 397                 discard = old;
 398         }
 399
 400         /* Check more often if replication is ongoing. */
 401         if (new->ro_replicating)
 402                 volume->update_at = ktime_get_real_seconds() + 10 * 60;
 403         else
 404                 volume->update_at = ktime_get_real_seconds() + afs_volume_record_life;
 405         write_unlock(&volume->servers_lock);
 406
 407         if (discard == old)
 408                 afs_reattach_volume_to_servers(volume, new, old);
 409         afs_put_serverlist(volume->cell->net, discard);
 410         ret = 0;
 411 error_vldb:
 412         kfree(vldb);
 413 error:
 414         _leave(" = %d", ret);
 415         return ret;
 416 }
 417
 418 /*
 419  * Make sure the volume record is up to date.
 420  */
 421 int afs_check_volume_status(struct afs_volume *volume, struct afs_operation *op)
 422 {
 423         int ret, retries = 0;
 424
 425         _enter("");
 426
 427 retry:
 428         if (test_bit(AFS_VOLUME_WAIT, &volume->flags))
 429                 goto wait;
 430         if (volume->update_at <= ktime_get_real_seconds() ||
 431             test_bit(AFS_VOLUME_NEEDS_UPDATE, &volume->flags))
 432                 goto update;
 433         _leave(" = 0");
 434         return 0;
 435
 436 update:
 437         if (!test_and_set_bit_lock(AFS_VOLUME_UPDATING, &volume->flags)) {
 438                 clear_bit(AFS_VOLUME_NEEDS_UPDATE, &volume->flags);
 439                 ret = afs_update_volume_status(volume, op->key);
 440                 if (ret < 0)
 441                         set_bit(AFS_VOLUME_NEEDS_UPDATE, &volume->flags);
 442                 clear_bit_unlock(AFS_VOLUME_WAIT, &volume->flags);
 443                 clear_bit_unlock(AFS_VOLUME_UPDATING, &volume->flags);
 444                 wake_up_bit(&volume->flags, AFS_VOLUME_WAIT);
 445                 _leave(" = %d", ret);
 446                 return ret;
 447         }
 448
 449 wait:
 450         if (!test_bit(AFS_VOLUME_WAIT, &volume->flags)) {
 451                 _leave(" = 0 [no wait]");
 452                 return 0;
 453         }
 454
 455         ret = wait_on_bit(&volume->flags, AFS_VOLUME_WAIT,
 456                           (op->flags & AFS_OPERATION_UNINTR) ?
 457                           TASK_UNINTERRUPTIBLE : TASK_INTERRUPTIBLE);
 458         if (ret == -ERESTARTSYS) {
 459                 _leave(" = %d", ret);
 460                 return ret;
 461         }
 462
 463         retries++;
 464         if (retries == 4) {
 465                 _leave(" = -ESTALE");
 466                 return -ESTALE;
 467         }
 468         goto retry;
 469 }