fs/afs/server.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /* AFS server record 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/sched.h>
   9 #include <linux/slab.h>
  10 #include "afs_fs.h"
  11 #include "internal.h"
  12 #include "protocol_yfs.h"
  13
  14 static unsigned afs_server_gc_delay = 10;       /* Server record timeout in seconds */
  15 static unsigned afs_server_update_delay = 30;   /* Time till VLDB recheck in secs */
  16 static atomic_t afs_server_debug_id;
  17
  18 static void afs_inc_servers_outstanding(struct afs_net *net)
  19 {
  20         atomic_inc(&net->servers_outstanding);
  21 }
  22
  23 static void afs_dec_servers_outstanding(struct afs_net *net)
  24 {
  25         if (atomic_dec_and_test(&net->servers_outstanding))
  26                 wake_up_var(&net->servers_outstanding);
  27 }
  28
  29 /*
  30  * Find a server by one of its addresses.
  31  */
  32 struct afs_server *afs_find_server(struct afs_net *net,
  33                                    const struct sockaddr_rxrpc *srx)
  34 {
  35         const struct afs_addr_list *alist;
  36         struct afs_server *server = NULL;
  37         unsigned int i;
  38         int seq = 0, diff;
  39
  40         rcu_read_lock();
  41
  42         do {
  43                 if (server)
  44                         afs_put_server(net, server, afs_server_trace_put_find_rsq);
  45                 server = NULL;
  46                 read_seqbegin_or_lock(&net->fs_addr_lock, &seq);
  47
  48                 if (srx->transport.family == AF_INET6) {
  49                         const struct sockaddr_in6 *a = &srx->transport.sin6, *b;
  50                         hlist_for_each_entry_rcu(server, &net->fs_addresses6, addr6_link) {
  51                                 alist = rcu_dereference(server->addresses);
  52                                 for (i = alist->nr_ipv4; i < alist->nr_addrs; i++) {
  53                                         b = &alist->addrs[i].transport.sin6;
  54                                         diff = ((u16 __force)a->sin6_port -
  55                                                 (u16 __force)b->sin6_port);
  56                                         if (diff == 0)
  57                                                 diff = memcmp(&a->sin6_addr,
  58                                                               &b->sin6_addr,
  59                                                               sizeof(struct in6_addr));
  60                                         if (diff == 0)
  61                                                 goto found;
  62                                 }
  63                         }
  64                 } else {
  65                         const struct sockaddr_in *a = &srx->transport.sin, *b;
  66                         hlist_for_each_entry_rcu(server, &net->fs_addresses4, addr4_link) {
  67                                 alist = rcu_dereference(server->addresses);
  68                                 for (i = 0; i < alist->nr_ipv4; i++) {
  69                                         b = &alist->addrs[i].transport.sin;
  70                                         diff = ((u16 __force)a->sin_port -
  71                                                 (u16 __force)b->sin_port);
  72                                         if (diff == 0)
  73                                                 diff = ((u32 __force)a->sin_addr.s_addr -
  74                                                         (u32 __force)b->sin_addr.s_addr);
  75                                         if (diff == 0)
  76                                                 goto found;
  77                                 }
  78                         }
  79                 }
  80
  81                 server = NULL;
  82         found:
  83                 if (server && !atomic_inc_not_zero(&server->usage))
  84                         server = NULL;
  85
  86         } while (need_seqretry(&net->fs_addr_lock, seq));
  87
  88         done_seqretry(&net->fs_addr_lock, seq);
  89
  90         rcu_read_unlock();
  91         return server;
  92 }
  93
  94 /*
  95  * Look up a server by its UUID
  96  */
  97 struct afs_server *afs_find_server_by_uuid(struct afs_net *net, const uuid_t *uuid)
  98 {
  99         struct afs_server *server = NULL;
 100         struct rb_node *p;
 101         int diff, seq = 0;
 102
 103         _enter("%pU", uuid);
 104
 105         do {
 106                 /* Unfortunately, rbtree walking doesn't give reliable results
 107                  * under just the RCU read lock, so we have to check for
 108                  * changes.
 109                  */
 110                 if (server)
 111                         afs_put_server(net, server, afs_server_trace_put_uuid_rsq);
 112                 server = NULL;
 113
 114                 read_seqbegin_or_lock(&net->fs_lock, &seq);
 115
 116                 p = net->fs_servers.rb_node;
 117                 while (p) {
 118                         server = rb_entry(p, struct afs_server, uuid_rb);
 119
 120                         diff = memcmp(uuid, &server->uuid, sizeof(*uuid));
 121                         if (diff < 0) {
 122                                 p = p->rb_left;
 123                         } else if (diff > 0) {
 124                                 p = p->rb_right;
 125                         } else {
 126                                 afs_get_server(server, afs_server_trace_get_by_uuid);
 127                                 break;
 128                         }
 129
 130                         server = NULL;
 131                 }
 132         } while (need_seqretry(&net->fs_lock, seq));
 133
 134         done_seqretry(&net->fs_lock, seq);
 135
 136         _leave(" = %p", server);
 137         return server;
 138 }
 139
 140 /*
 141  * Install a server record in the namespace tree
 142  */
 143 static struct afs_server *afs_install_server(struct afs_net *net,
 144                                              struct afs_server *candidate)
 145 {
 146         const struct afs_addr_list *alist;
 147         struct afs_server *server;
 148         struct rb_node **pp, *p;
 149         int diff;
 150
 151         _enter("%p", candidate);
 152
 153         write_seqlock(&net->fs_lock);
 154
 155         /* Firstly install the server in the UUID lookup tree */
 156         pp = &net->fs_servers.rb_node;
 157         p = NULL;
 158         while (*pp) {
 159                 p = *pp;
 160                 _debug("- consider %p", p);
 161                 server = rb_entry(p, struct afs_server, uuid_rb);
 162                 diff = memcmp(&candidate->uuid, &server->uuid, sizeof(uuid_t));
 163                 if (diff < 0)
 164                         pp = &(*pp)->rb_left;
 165                 else if (diff > 0)
 166                         pp = &(*pp)->rb_right;
 167                 else
 168                         goto exists;
 169         }
 170
 171         server = candidate;
 172         rb_link_node(&server->uuid_rb, p, pp);
 173         rb_insert_color(&server->uuid_rb, &net->fs_servers);
 174         hlist_add_head_rcu(&server->proc_link, &net->fs_proc);
 175
 176         write_seqlock(&net->fs_addr_lock);
 177         alist = rcu_dereference_protected(server->addresses,
 178                                           lockdep_is_held(&net->fs_addr_lock.lock));
 179
 180         /* Secondly, if the server has any IPv4 and/or IPv6 addresses, install
 181          * it in the IPv4 and/or IPv6 reverse-map lists.
 182          *
 183          * TODO: For speed we want to use something other than a flat list
 184          * here; even sorting the list in terms of lowest address would help a
 185          * bit, but anything we might want to do gets messy and memory
 186          * intensive.
 187          */
 188         if (alist->nr_ipv4 > 0)
 189                 hlist_add_head_rcu(&server->addr4_link, &net->fs_addresses4);
 190         if (alist->nr_addrs > alist->nr_ipv4)
 191                 hlist_add_head_rcu(&server->addr6_link, &net->fs_addresses6);
 192
 193         write_sequnlock(&net->fs_addr_lock);
 194
 195 exists:
 196         afs_get_server(server, afs_server_trace_get_install);
 197         write_sequnlock(&net->fs_lock);
 198         return server;
 199 }
 200
 201 /*
 202  * allocate a new server record
 203  */
 204 static struct afs_server *afs_alloc_server(struct afs_net *net,
 205                                            const uuid_t *uuid,
 206                                            struct afs_addr_list *alist)
 207 {
 208         struct afs_server *server;
 209
 210         _enter("");
 211
 212         server = kzalloc(sizeof(struct afs_server), GFP_KERNEL);
 213         if (!server)
 214                 goto enomem;
 215
 216         atomic_set(&server->usage, 1);
 217         server->debug_id = atomic_inc_return(&afs_server_debug_id);
 218         RCU_INIT_POINTER(server->addresses, alist);
 219         server->addr_version = alist->version;
 220         server->uuid = *uuid;
 221         server->update_at = ktime_get_real_seconds() + afs_server_update_delay;
 222         rwlock_init(&server->fs_lock);
 223         INIT_HLIST_HEAD(&server->cb_volumes);
 224         rwlock_init(&server->cb_break_lock);
 225         init_waitqueue_head(&server->probe_wq);
 226         spin_lock_init(&server->probe_lock);
 227
 228         afs_inc_servers_outstanding(net);
 229         trace_afs_server(server, 1, afs_server_trace_alloc);
 230         _leave(" = %p", server);
 231         return server;
 232
 233 enomem:
 234         _leave(" = NULL [nomem]");
 235         return NULL;
 236 }
 237
 238 /*
 239  * Look up an address record for a server
 240  */
 241 static struct afs_addr_list *afs_vl_lookup_addrs(struct afs_cell *cell,
 242                                                  struct key *key, const uuid_t *uuid)
 243 {
 244         struct afs_vl_cursor vc;
 245         struct afs_addr_list *alist = NULL;
 246         int ret;
 247
 248         ret = -ERESTARTSYS;
 249         if (afs_begin_vlserver_operation(&vc, cell, key)) {
 250                 while (afs_select_vlserver(&vc)) {
 251                         if (test_bit(AFS_VLSERVER_FL_IS_YFS, &vc.server->flags))
 252                                 alist = afs_yfsvl_get_endpoints(&vc, uuid);
 253                         else
 254                                 alist = afs_vl_get_addrs_u(&vc, uuid);
 255                 }
 256
 257                 ret = afs_end_vlserver_operation(&vc);
 258         }
 259
 260         return ret < 0 ? ERR_PTR(ret) : alist;
 261 }
 262
 263 /*
 264  * Get or create a fileserver record.
 265  */
 266 struct afs_server *afs_lookup_server(struct afs_cell *cell, struct key *key,
 267                                      const uuid_t *uuid)
 268 {
 269         struct afs_addr_list *alist;
 270         struct afs_server *server, *candidate;
 271
 272         _enter("%p,%pU", cell->net, uuid);
 273
 274         server = afs_find_server_by_uuid(cell->net, uuid);
 275         if (server)
 276                 return server;
 277
 278         alist = afs_vl_lookup_addrs(cell, key, uuid);
 279         if (IS_ERR(alist))
 280                 return ERR_CAST(alist);
 281
 282         candidate = afs_alloc_server(cell->net, uuid, alist);
 283         if (!candidate) {
 284                 afs_put_addrlist(alist);
 285                 return ERR_PTR(-ENOMEM);
 286         }
 287
 288         server = afs_install_server(cell->net, candidate);
 289         if (server != candidate) {
 290                 afs_put_addrlist(alist);
 291                 kfree(candidate);
 292         }
 293
 294         _leave(" = %p{%d}", server, atomic_read(&server->usage));
 295         return server;
 296 }
 297
 298 /*
 299  * Set the server timer to fire after a given delay, assuming it's not already
 300  * set for an earlier time.
 301  */
 302 static void afs_set_server_timer(struct afs_net *net, time64_t delay)
 303 {
 304         if (net->live) {
 305                 afs_inc_servers_outstanding(net);
 306                 if (timer_reduce(&net->fs_timer, jiffies + delay * HZ))
 307                         afs_dec_servers_outstanding(net);
 308         }
 309 }
 310
 311 /*
 312  * Server management timer.  We have an increment on fs_outstanding that we
 313  * need to pass along to the work item.
 314  */
 315 void afs_servers_timer(struct timer_list *timer)
 316 {
 317         struct afs_net *net = container_of(timer, struct afs_net, fs_timer);
 318
 319         _enter("");
 320         if (!queue_work(afs_wq, &net->fs_manager))
 321                 afs_dec_servers_outstanding(net);
 322 }
 323
 324 /*
 325  * Get a reference on a server object.
 326  */
 327 struct afs_server *afs_get_server(struct afs_server *server,
 328                                   enum afs_server_trace reason)
 329 {
 330         unsigned int u = atomic_inc_return(&server->usage);
 331
 332         trace_afs_server(server, u, reason);
 333         return server;
 334 }
 335
 336 /*
 337  * Release a reference on a server record.
 338  */
 339 void afs_put_server(struct afs_net *net, struct afs_server *server,
 340                     enum afs_server_trace reason)
 341 {
 342         unsigned int usage;
 343
 344         if (!server)
 345                 return;
 346
 347         server->put_time = ktime_get_real_seconds();
 348
 349         usage = atomic_dec_return(&server->usage);
 350
 351         trace_afs_server(server, usage, reason);
 352
 353         if (likely(usage > 0))
 354                 return;
 355
 356         afs_set_server_timer(net, afs_server_gc_delay);
 357 }
 358
 359 static void afs_server_rcu(struct rcu_head *rcu)
 360 {
 361         struct afs_server *server = container_of(rcu, struct afs_server, rcu);
 362
 363         trace_afs_server(server, atomic_read(&server->usage),
 364                          afs_server_trace_free);
 365         afs_put_addrlist(rcu_access_pointer(server->addresses));
 366         kfree(server);
 367 }
 368
 369 /*
 370  * destroy a dead server
 371  */
 372 static void afs_destroy_server(struct afs_net *net, struct afs_server *server)
 373 {
 374         struct afs_addr_list *alist = rcu_access_pointer(server->addresses);
 375         struct afs_addr_cursor ac = {
 376                 .alist  = alist,
 377                 .index  = alist->preferred,
 378                 .error  = 0,
 379         };
 380
 381         trace_afs_server(server, atomic_read(&server->usage),
 382                          afs_server_trace_give_up_cb);
 383
 384         if (test_bit(AFS_SERVER_FL_MAY_HAVE_CB, &server->flags))
 385                 afs_fs_give_up_all_callbacks(net, server, &ac, NULL);
 386
 387         wait_var_event(&server->probe_outstanding,
 388                        atomic_read(&server->probe_outstanding) == 0);
 389
 390         trace_afs_server(server, atomic_read(&server->usage),
 391                          afs_server_trace_destroy);
 392         call_rcu(&server->rcu, afs_server_rcu);
 393         afs_dec_servers_outstanding(net);
 394 }
 395
 396 /*
 397  * Garbage collect any expired servers.
 398  */
 399 static void afs_gc_servers(struct afs_net *net, struct afs_server *gc_list)
 400 {
 401         struct afs_server *server;
 402         bool deleted;
 403         int usage;
 404
 405         while ((server = gc_list)) {
 406                 gc_list = server->gc_next;
 407
 408                 write_seqlock(&net->fs_lock);
 409                 usage = 1;
 410                 deleted = atomic_try_cmpxchg(&server->usage, &usage, 0);
 411                 trace_afs_server(server, usage, afs_server_trace_gc);
 412                 if (deleted) {
 413                         rb_erase(&server->uuid_rb, &net->fs_servers);
 414                         hlist_del_rcu(&server->proc_link);
 415                 }
 416                 write_sequnlock(&net->fs_lock);
 417
 418                 if (deleted) {
 419                         write_seqlock(&net->fs_addr_lock);
 420                         if (!hlist_unhashed(&server->addr4_link))
 421                                 hlist_del_rcu(&server->addr4_link);
 422                         if (!hlist_unhashed(&server->addr6_link))
 423                                 hlist_del_rcu(&server->addr6_link);
 424                         write_sequnlock(&net->fs_addr_lock);
 425                         afs_destroy_server(net, server);
 426                 }
 427         }
 428 }
 429
 430 /*
 431  * Manage the records of servers known to be within a network namespace.  This
 432  * includes garbage collecting unused servers.
 433  *
 434  * Note also that we were given an increment on net->servers_outstanding by
 435  * whoever queued us that we need to deal with before returning.
 436  */
 437 void afs_manage_servers(struct work_struct *work)
 438 {
 439         struct afs_net *net = container_of(work, struct afs_net, fs_manager);
 440         struct afs_server *gc_list = NULL;
 441         struct rb_node *cursor;
 442         time64_t now = ktime_get_real_seconds(), next_manage = TIME64_MAX;
 443         bool purging = !net->live;
 444
 445         _enter("");
 446
 447         /* Trawl the server list looking for servers that have expired from
 448          * lack of use.
 449          */
 450         read_seqlock_excl(&net->fs_lock);
 451
 452         for (cursor = rb_first(&net->fs_servers); cursor; cursor = rb_next(cursor)) {
 453                 struct afs_server *server =
 454                         rb_entry(cursor, struct afs_server, uuid_rb);
 455                 int usage = atomic_read(&server->usage);
 456
 457                 _debug("manage %pU %u", &server->uuid, usage);
 458
 459                 ASSERTCMP(usage, >=, 1);
 460                 ASSERTIFCMP(purging, usage, ==, 1);
 461
 462                 if (usage == 1) {
 463                         time64_t expire_at = server->put_time;
 464
 465                         if (!test_bit(AFS_SERVER_FL_VL_FAIL, &server->flags) &&
 466                             !test_bit(AFS_SERVER_FL_NOT_FOUND, &server->flags))
 467                                 expire_at += afs_server_gc_delay;
 468                         if (purging || expire_at <= now) {
 469                                 server->gc_next = gc_list;
 470                                 gc_list = server;
 471                         } else if (expire_at < next_manage) {
 472                                 next_manage = expire_at;
 473                         }
 474                 }
 475         }
 476
 477         read_sequnlock_excl(&net->fs_lock);
 478
 479         /* Update the timer on the way out.  We have to pass an increment on
 480          * servers_outstanding in the namespace that we are in to the timer or
 481          * the work scheduler.
 482          */
 483         if (!purging && next_manage < TIME64_MAX) {
 484                 now = ktime_get_real_seconds();
 485
 486                 if (next_manage - now <= 0) {
 487                         if (queue_work(afs_wq, &net->fs_manager))
 488                                 afs_inc_servers_outstanding(net);
 489                 } else {
 490                         afs_set_server_timer(net, next_manage - now);
 491                 }
 492         }
 493
 494         afs_gc_servers(net, gc_list);
 495
 496         afs_dec_servers_outstanding(net);
 497         _leave(" [%d]", atomic_read(&net->servers_outstanding));
 498 }
 499
 500 static void afs_queue_server_manager(struct afs_net *net)
 501 {
 502         afs_inc_servers_outstanding(net);
 503         if (!queue_work(afs_wq, &net->fs_manager))
 504                 afs_dec_servers_outstanding(net);
 505 }
 506
 507 /*
 508  * Purge list of servers.
 509  */
 510 void afs_purge_servers(struct afs_net *net)
 511 {
 512         _enter("");
 513
 514         if (del_timer_sync(&net->fs_timer))
 515                 atomic_dec(&net->servers_outstanding);
 516
 517         afs_queue_server_manager(net);
 518
 519         _debug("wait");
 520         wait_var_event(&net->servers_outstanding,
 521                        !atomic_read(&net->servers_outstanding));
 522         _leave("");
 523 }
 524
 525 /*
 526  * Get an update for a server's address list.
 527  */
 528 static noinline bool afs_update_server_record(struct afs_fs_cursor *fc, struct afs_server *server)
 529 {
 530         struct afs_addr_list *alist, *discard;
 531
 532         _enter("");
 533
 534         trace_afs_server(server, atomic_read(&server->usage), afs_server_trace_update);
 535
 536         alist = afs_vl_lookup_addrs(fc->vnode->volume->cell, fc->key,
 537                                     &server->uuid);
 538         if (IS_ERR(alist)) {
 539                 if ((PTR_ERR(alist) == -ERESTARTSYS ||
 540                      PTR_ERR(alist) == -EINTR) &&
 541                     !(fc->flags & AFS_FS_CURSOR_INTR) &&
 542                     server->addresses) {
 543                         _leave(" = t [intr]");
 544                         return true;
 545                 }
 546                 fc->error = PTR_ERR(alist);
 547                 _leave(" = f [%d]", fc->error);
 548                 return false;
 549         }
 550
 551         discard = alist;
 552         if (server->addr_version != alist->version) {
 553                 write_lock(&server->fs_lock);
 554                 discard = rcu_dereference_protected(server->addresses,
 555                                                     lockdep_is_held(&server->fs_lock));
 556                 rcu_assign_pointer(server->addresses, alist);
 557                 server->addr_version = alist->version;
 558                 write_unlock(&server->fs_lock);
 559         }
 560
 561         server->update_at = ktime_get_real_seconds() + afs_server_update_delay;
 562         afs_put_addrlist(discard);
 563         _leave(" = t");
 564         return true;
 565 }
 566
 567 /*
 568  * See if a server's address list needs updating.
 569  */
 570 bool afs_check_server_record(struct afs_fs_cursor *fc, struct afs_server *server)
 571 {
 572         time64_t now = ktime_get_real_seconds();
 573         long diff;
 574         bool success;
 575         int ret, retries = 0;
 576
 577         _enter("");
 578
 579         ASSERT(server);
 580
 581 retry:
 582         diff = READ_ONCE(server->update_at) - now;
 583         if (diff > 0) {
 584                 _leave(" = t [not now %ld]", diff);
 585                 return true;
 586         }
 587
 588         if (!test_and_set_bit_lock(AFS_SERVER_FL_UPDATING, &server->flags)) {
 589                 success = afs_update_server_record(fc, server);
 590                 clear_bit_unlock(AFS_SERVER_FL_UPDATING, &server->flags);
 591                 wake_up_bit(&server->flags, AFS_SERVER_FL_UPDATING);
 592                 _leave(" = %d", success);
 593                 return success;
 594         }
 595
 596         ret = wait_on_bit(&server->flags, AFS_SERVER_FL_UPDATING,
 597                           TASK_INTERRUPTIBLE);
 598         if (ret == -ERESTARTSYS) {
 599                 if (!(fc->flags & AFS_FS_CURSOR_INTR) && server->addresses) {
 600                         _leave(" = t [intr]");
 601                         return true;
 602                 }
 603                 fc->error = ret;
 604                 _leave(" = f [intr]");
 605                 return false;
 606         }
 607
 608         retries++;
 609         if (retries == 4) {
 610                 _leave(" = f [stale]");
 611                 ret = -ESTALE;
 612                 return false;
 613         }
 614         goto retry;
 615 }