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 14static unsigned afs_server_gc_delay = 10; /* Server record timeout in seconds */ 15static atomic_t afs_server_debug_id; 16 17static struct afs_server *afs_maybe_use_server(struct afs_server *, 18 enum afs_server_trace); 19static void __afs_put_server(struct afs_net *, struct afs_server *); 20 21/* 22 * Find a server by one of its addresses. 23 */ 24struct afs_server *afs_find_server(struct afs_net *net, const struct rxrpc_peer *peer) 25{ 26 const struct afs_endpoint_state *estate; 27 const struct afs_addr_list *alist; 28 struct afs_server *server = NULL; 29 unsigned int i; 30 int seq = 1; 31 32 rcu_read_lock(); 33 34 do { 35 if (server) 36 afs_unuse_server_notime(net, server, afs_server_trace_put_find_rsq); 37 server = NULL; 38 seq++; /* 2 on the 1st/lockless path, otherwise odd */ 39 read_seqbegin_or_lock(&net->fs_addr_lock, &seq); 40 41 hlist_for_each_entry_rcu(server, &net->fs_addresses, addr_link) { 42 estate = rcu_dereference(server->endpoint_state); 43 alist = estate->addresses; 44 for (i = 0; i < alist->nr_addrs; i++) 45 if (alist->addrs[i].peer == peer) 46 goto found; 47 } 48 49 server = NULL; 50 continue; 51 found: 52 server = afs_maybe_use_server(server, afs_server_trace_get_by_addr); 53 54 } while (need_seqretry(&net->fs_addr_lock, seq)); 55 56 done_seqretry(&net->fs_addr_lock, seq); 57 58 rcu_read_unlock(); 59 return server; 60} 61 62/* 63 * Look up a server by its UUID and mark it active. 64 */ 65struct afs_server *afs_find_server_by_uuid(struct afs_net *net, const uuid_t *uuid) 66{ 67 struct afs_server *server = NULL; 68 struct rb_node *p; 69 int diff, seq = 1; 70 71 _enter("%pU", uuid); 72 73 do { 74 /* Unfortunately, rbtree walking doesn't give reliable results 75 * under just the RCU read lock, so we have to check for 76 * changes. 77 */ 78 if (server) 79 afs_unuse_server(net, server, afs_server_trace_put_uuid_rsq); 80 server = NULL; 81 seq++; /* 2 on the 1st/lockless path, otherwise odd */ 82 read_seqbegin_or_lock(&net->fs_lock, &seq); 83 84 p = net->fs_servers.rb_node; 85 while (p) { 86 server = rb_entry(p, struct afs_server, uuid_rb); 87 88 diff = memcmp(uuid, &server->uuid, sizeof(*uuid)); 89 if (diff < 0) { 90 p = p->rb_left; 91 } else if (diff > 0) { 92 p = p->rb_right; 93 } else { 94 afs_use_server(server, afs_server_trace_get_by_uuid); 95 break; 96 } 97 98 server = NULL; 99 } 100 } while (need_seqretry(&net->fs_lock, seq)); 101 102 done_seqretry(&net->fs_lock, seq); 103 104 _leave(" = %p", server); 105 return server; 106} 107 108/* 109 * Install a server record in the namespace tree. If there's a clash, we stick 110 * it into a list anchored on whichever afs_server struct is actually in the 111 * tree. 112 */ 113static struct afs_server *afs_install_server(struct afs_cell *cell, 114 struct afs_server *candidate) 115{ 116 const struct afs_endpoint_state *estate; 117 const struct afs_addr_list *alist; 118 struct afs_server *server, *next; 119 struct afs_net *net = cell->net; 120 struct rb_node **pp, *p; 121 int diff; 122 123 _enter("%p", candidate); 124 125 write_seqlock(&net->fs_lock); 126 127 /* Firstly install the server in the UUID lookup tree */ 128 pp = &net->fs_servers.rb_node; 129 p = NULL; 130 while (*pp) { 131 p = *pp; 132 _debug("- consider %p", p); 133 server = rb_entry(p, struct afs_server, uuid_rb); 134 diff = memcmp(&candidate->uuid, &server->uuid, sizeof(uuid_t)); 135 if (diff < 0) { 136 pp = &(*pp)->rb_left; 137 } else if (diff > 0) { 138 pp = &(*pp)->rb_right; 139 } else { 140 if (server->cell == cell) 141 goto exists; 142 143 /* We have the same UUID representing servers in 144 * different cells. Append the new server to the list. 145 */ 146 for (;;) { 147 next = rcu_dereference_protected( 148 server->uuid_next, 149 lockdep_is_held(&net->fs_lock.lock)); 150 if (!next) 151 break; 152 server = next; 153 } 154 rcu_assign_pointer(server->uuid_next, candidate); 155 candidate->uuid_prev = server; 156 server = candidate; 157 goto added_dup; 158 } 159 } 160 161 server = candidate; 162 rb_link_node(&server->uuid_rb, p, pp); 163 rb_insert_color(&server->uuid_rb, &net->fs_servers); 164 hlist_add_head_rcu(&server->proc_link, &net->fs_proc); 165 166added_dup: 167 write_seqlock(&net->fs_addr_lock); 168 estate = rcu_dereference_protected(server->endpoint_state, 169 lockdep_is_held(&net->fs_addr_lock.lock)); 170 alist = estate->addresses; 171 172 /* Secondly, if the server has any IPv4 and/or IPv6 addresses, install 173 * it in the IPv4 and/or IPv6 reverse-map lists. 174 * 175 * TODO: For speed we want to use something other than a flat list 176 * here; even sorting the list in terms of lowest address would help a 177 * bit, but anything we might want to do gets messy and memory 178 * intensive. 179 */ 180 if (alist->nr_addrs > 0) 181 hlist_add_head_rcu(&server->addr_link, &net->fs_addresses); 182 183 write_sequnlock(&net->fs_addr_lock); 184 185exists: 186 afs_get_server(server, afs_server_trace_get_install); 187 write_sequnlock(&net->fs_lock); 188 return server; 189} 190 191/* 192 * Allocate a new server record and mark it active. 193 */ 194static struct afs_server *afs_alloc_server(struct afs_cell *cell, 195 const uuid_t *uuid, 196 struct afs_addr_list *alist) 197{ 198 struct afs_endpoint_state *estate; 199 struct afs_server *server; 200 struct afs_net *net = cell->net; 201 202 _enter(""); 203 204 server = kzalloc(sizeof(struct afs_server), GFP_KERNEL); 205 if (!server) 206 goto enomem; 207 208 estate = kzalloc(sizeof(struct afs_endpoint_state), GFP_KERNEL); 209 if (!estate) 210 goto enomem_server; 211 212 refcount_set(&server->ref, 1); 213 atomic_set(&server->active, 1); 214 server->debug_id = atomic_inc_return(&afs_server_debug_id); 215 server->addr_version = alist->version; 216 server->uuid = *uuid; 217 rwlock_init(&server->fs_lock); 218 INIT_LIST_HEAD(&server->volumes); 219 init_waitqueue_head(&server->probe_wq); 220 INIT_LIST_HEAD(&server->probe_link); 221 spin_lock_init(&server->probe_lock); 222 server->cell = cell; 223 server->rtt = UINT_MAX; 224 server->service_id = FS_SERVICE; 225 226 server->probe_counter = 1; 227 server->probed_at = jiffies - LONG_MAX / 2; 228 refcount_set(&estate->ref, 1); 229 estate->addresses = alist; 230 estate->server_id = server->debug_id; 231 estate->probe_seq = 1; 232 rcu_assign_pointer(server->endpoint_state, estate); 233 234 afs_inc_servers_outstanding(net); 235 trace_afs_server(server->debug_id, 1, 1, afs_server_trace_alloc); 236 trace_afs_estate(estate->server_id, estate->probe_seq, refcount_read(&estate->ref), 237 afs_estate_trace_alloc_server); 238 _leave(" = %p", server); 239 return server; 240 241enomem_server: 242 kfree(server); 243enomem: 244 _leave(" = NULL [nomem]"); 245 return NULL; 246} 247 248/* 249 * Look up an address record for a server 250 */ 251static struct afs_addr_list *afs_vl_lookup_addrs(struct afs_cell *cell, 252 struct key *key, const uuid_t *uuid) 253{ 254 struct afs_vl_cursor vc; 255 struct afs_addr_list *alist = NULL; 256 int ret; 257 258 ret = -ERESTARTSYS; 259 if (afs_begin_vlserver_operation(&vc, cell, key)) { 260 while (afs_select_vlserver(&vc)) { 261 if (test_bit(AFS_VLSERVER_FL_IS_YFS, &vc.server->flags)) 262 alist = afs_yfsvl_get_endpoints(&vc, uuid); 263 else 264 alist = afs_vl_get_addrs_u(&vc, uuid); 265 } 266 267 ret = afs_end_vlserver_operation(&vc); 268 } 269 270 return ret < 0 ? ERR_PTR(ret) : alist; 271} 272 273/* 274 * Get or create a fileserver record. 275 */ 276struct afs_server *afs_lookup_server(struct afs_cell *cell, struct key *key, 277 const uuid_t *uuid, u32 addr_version) 278{ 279 struct afs_addr_list *alist; 280 struct afs_server *server, *candidate; 281 282 _enter("%p,%pU", cell->net, uuid); 283 284 server = afs_find_server_by_uuid(cell->net, uuid); 285 if (server) { 286 if (server->addr_version != addr_version) 287 set_bit(AFS_SERVER_FL_NEEDS_UPDATE, &server->flags); 288 return server; 289 } 290 291 alist = afs_vl_lookup_addrs(cell, key, uuid); 292 if (IS_ERR(alist)) 293 return ERR_CAST(alist); 294 295 candidate = afs_alloc_server(cell, uuid, alist); 296 if (!candidate) { 297 afs_put_addrlist(alist, afs_alist_trace_put_server_oom); 298 return ERR_PTR(-ENOMEM); 299 } 300 301 server = afs_install_server(cell, candidate); 302 if (server != candidate) { 303 afs_put_addrlist(alist, afs_alist_trace_put_server_dup); 304 kfree(candidate); 305 } else { 306 /* Immediately dispatch an asynchronous probe to each interface 307 * on the fileserver. This will make sure the repeat-probing 308 * service is started. 309 */ 310 afs_fs_probe_fileserver(cell->net, server, alist, key); 311 } 312 313 return server; 314} 315 316/* 317 * Set the server timer to fire after a given delay, assuming it's not already 318 * set for an earlier time. 319 */ 320static void afs_set_server_timer(struct afs_net *net, time64_t delay) 321{ 322 if (net->live) { 323 afs_inc_servers_outstanding(net); 324 if (timer_reduce(&net->fs_timer, jiffies + delay * HZ)) 325 afs_dec_servers_outstanding(net); 326 } 327} 328 329/* 330 * Server management timer. We have an increment on fs_outstanding that we 331 * need to pass along to the work item. 332 */ 333void afs_servers_timer(struct timer_list *timer) 334{ 335 struct afs_net *net = container_of(timer, struct afs_net, fs_timer); 336 337 _enter(""); 338 if (!queue_work(afs_wq, &net->fs_manager)) 339 afs_dec_servers_outstanding(net); 340} 341 342/* 343 * Get a reference on a server object. 344 */ 345struct afs_server *afs_get_server(struct afs_server *server, 346 enum afs_server_trace reason) 347{ 348 unsigned int a; 349 int r; 350 351 __refcount_inc(&server->ref, &r); 352 a = atomic_read(&server->active); 353 trace_afs_server(server->debug_id, r + 1, a, reason); 354 return server; 355} 356 357/* 358 * Try to get a reference on a server object. 359 */ 360static struct afs_server *afs_maybe_use_server(struct afs_server *server, 361 enum afs_server_trace reason) 362{ 363 unsigned int a; 364 int r; 365 366 if (!__refcount_inc_not_zero(&server->ref, &r)) 367 return NULL; 368 369 a = atomic_inc_return(&server->active); 370 trace_afs_server(server->debug_id, r + 1, a, reason); 371 return server; 372} 373 374/* 375 * Get an active count on a server object. 376 */ 377struct afs_server *afs_use_server(struct afs_server *server, enum afs_server_trace reason) 378{ 379 unsigned int a; 380 int r; 381 382 __refcount_inc(&server->ref, &r); 383 a = atomic_inc_return(&server->active); 384 385 trace_afs_server(server->debug_id, r + 1, a, reason); 386 return server; 387} 388 389/* 390 * Release a reference on a server record. 391 */ 392void afs_put_server(struct afs_net *net, struct afs_server *server, 393 enum afs_server_trace reason) 394{ 395 unsigned int a, debug_id = server->debug_id; 396 bool zero; 397 int r; 398 399 if (!server) 400 return; 401 402 a = atomic_read(&server->active); 403 zero = __refcount_dec_and_test(&server->ref, &r); 404 trace_afs_server(debug_id, r - 1, a, reason); 405 if (unlikely(zero)) 406 __afs_put_server(net, server); 407} 408 409/* 410 * Drop an active count on a server object without updating the last-unused 411 * time. 412 */ 413void afs_unuse_server_notime(struct afs_net *net, struct afs_server *server, 414 enum afs_server_trace reason) 415{ 416 if (server) { 417 unsigned int active = atomic_dec_return(&server->active); 418 419 if (active == 0) 420 afs_set_server_timer(net, afs_server_gc_delay); 421 afs_put_server(net, server, reason); 422 } 423} 424 425/* 426 * Drop an active count on a server object. 427 */ 428void afs_unuse_server(struct afs_net *net, struct afs_server *server, 429 enum afs_server_trace reason) 430{ 431 if (server) { 432 server->unuse_time = ktime_get_real_seconds(); 433 afs_unuse_server_notime(net, server, reason); 434 } 435} 436 437static void afs_server_rcu(struct rcu_head *rcu) 438{ 439 struct afs_server *server = container_of(rcu, struct afs_server, rcu); 440 441 trace_afs_server(server->debug_id, refcount_read(&server->ref), 442 atomic_read(&server->active), afs_server_trace_free); 443 afs_put_endpoint_state(rcu_access_pointer(server->endpoint_state), 444 afs_estate_trace_put_server); 445 kfree(server); 446} 447 448static void __afs_put_server(struct afs_net *net, struct afs_server *server) 449{ 450 call_rcu(&server->rcu, afs_server_rcu); 451 afs_dec_servers_outstanding(net); 452} 453 454static void afs_give_up_callbacks(struct afs_net *net, struct afs_server *server) 455{ 456 struct afs_endpoint_state *estate = rcu_access_pointer(server->endpoint_state); 457 struct afs_addr_list *alist = estate->addresses; 458 459 afs_fs_give_up_all_callbacks(net, server, &alist->addrs[alist->preferred], NULL); 460} 461 462/* 463 * destroy a dead server 464 */ 465static void afs_destroy_server(struct afs_net *net, struct afs_server *server) 466{ 467 if (test_bit(AFS_SERVER_FL_MAY_HAVE_CB, &server->flags)) 468 afs_give_up_callbacks(net, server); 469 470 afs_put_server(net, server, afs_server_trace_destroy); 471} 472 473/* 474 * Garbage collect any expired servers. 475 */ 476static void afs_gc_servers(struct afs_net *net, struct afs_server *gc_list) 477{ 478 struct afs_server *server, *next, *prev; 479 int active; 480 481 while ((server = gc_list)) { 482 gc_list = server->gc_next; 483 484 write_seqlock(&net->fs_lock); 485 486 active = atomic_read(&server->active); 487 if (active == 0) { 488 trace_afs_server(server->debug_id, refcount_read(&server->ref), 489 active, afs_server_trace_gc); 490 next = rcu_dereference_protected( 491 server->uuid_next, lockdep_is_held(&net->fs_lock.lock)); 492 prev = server->uuid_prev; 493 if (!prev) { 494 /* The one at the front is in the tree */ 495 if (!next) { 496 rb_erase(&server->uuid_rb, &net->fs_servers); 497 } else { 498 rb_replace_node_rcu(&server->uuid_rb, 499 &next->uuid_rb, 500 &net->fs_servers); 501 next->uuid_prev = NULL; 502 } 503 } else { 504 /* This server is not at the front */ 505 rcu_assign_pointer(prev->uuid_next, next); 506 if (next) 507 next->uuid_prev = prev; 508 } 509 510 list_del(&server->probe_link); 511 hlist_del_rcu(&server->proc_link); 512 if (!hlist_unhashed(&server->addr_link)) 513 hlist_del_rcu(&server->addr_link); 514 } 515 write_sequnlock(&net->fs_lock); 516 517 if (active == 0) 518 afs_destroy_server(net, server); 519 } 520} 521 522/* 523 * Manage the records of servers known to be within a network namespace. This 524 * includes garbage collecting unused servers. 525 * 526 * Note also that we were given an increment on net->servers_outstanding by 527 * whoever queued us that we need to deal with before returning. 528 */ 529void afs_manage_servers(struct work_struct *work) 530{ 531 struct afs_net *net = container_of(work, struct afs_net, fs_manager); 532 struct afs_server *gc_list = NULL; 533 struct rb_node *cursor; 534 time64_t now = ktime_get_real_seconds(), next_manage = TIME64_MAX; 535 bool purging = !net->live; 536 537 _enter(""); 538 539 /* Trawl the server list looking for servers that have expired from 540 * lack of use. 541 */ 542 read_seqlock_excl(&net->fs_lock); 543 544 for (cursor = rb_first(&net->fs_servers); cursor; cursor = rb_next(cursor)) { 545 struct afs_server *server = 546 rb_entry(cursor, struct afs_server, uuid_rb); 547 int active = atomic_read(&server->active); 548 549 _debug("manage %pU %u", &server->uuid, active); 550 551 if (purging) { 552 trace_afs_server(server->debug_id, refcount_read(&server->ref), 553 active, afs_server_trace_purging); 554 if (active != 0) 555 pr_notice("Can't purge s=%08x\n", server->debug_id); 556 } 557 558 if (active == 0) { 559 time64_t expire_at = server->unuse_time; 560 561 if (!test_bit(AFS_SERVER_FL_VL_FAIL, &server->flags) && 562 !test_bit(AFS_SERVER_FL_NOT_FOUND, &server->flags)) 563 expire_at += afs_server_gc_delay; 564 if (purging || expire_at <= now) { 565 server->gc_next = gc_list; 566 gc_list = server; 567 } else if (expire_at < next_manage) { 568 next_manage = expire_at; 569 } 570 } 571 } 572 573 read_sequnlock_excl(&net->fs_lock); 574 575 /* Update the timer on the way out. We have to pass an increment on 576 * servers_outstanding in the namespace that we are in to the timer or 577 * the work scheduler. 578 */ 579 if (!purging && next_manage < TIME64_MAX) { 580 now = ktime_get_real_seconds(); 581 582 if (next_manage - now <= 0) { 583 if (queue_work(afs_wq, &net->fs_manager)) 584 afs_inc_servers_outstanding(net); 585 } else { 586 afs_set_server_timer(net, next_manage - now); 587 } 588 } 589 590 afs_gc_servers(net, gc_list); 591 592 afs_dec_servers_outstanding(net); 593 _leave(" [%d]", atomic_read(&net->servers_outstanding)); 594} 595 596static void afs_queue_server_manager(struct afs_net *net) 597{ 598 afs_inc_servers_outstanding(net); 599 if (!queue_work(afs_wq, &net->fs_manager)) 600 afs_dec_servers_outstanding(net); 601} 602 603/* 604 * Purge list of servers. 605 */ 606void afs_purge_servers(struct afs_net *net) 607{ 608 _enter(""); 609 610 if (del_timer_sync(&net->fs_timer)) 611 afs_dec_servers_outstanding(net); 612 613 afs_queue_server_manager(net); 614 615 _debug("wait"); 616 atomic_dec(&net->servers_outstanding); 617 wait_var_event(&net->servers_outstanding, 618 !atomic_read(&net->servers_outstanding)); 619 _leave(""); 620} 621 622/* 623 * Get an update for a server's address list. 624 */ 625static noinline bool afs_update_server_record(struct afs_operation *op, 626 struct afs_server *server, 627 struct key *key) 628{ 629 struct afs_endpoint_state *estate; 630 struct afs_addr_list *alist; 631 bool has_addrs; 632 633 _enter(""); 634 635 trace_afs_server(server->debug_id, refcount_read(&server->ref), 636 atomic_read(&server->active), 637 afs_server_trace_update); 638 639 alist = afs_vl_lookup_addrs(op->volume->cell, op->key, &server->uuid); 640 if (IS_ERR(alist)) { 641 rcu_read_lock(); 642 estate = rcu_dereference(server->endpoint_state); 643 has_addrs = estate->addresses; 644 rcu_read_unlock(); 645 646 if ((PTR_ERR(alist) == -ERESTARTSYS || 647 PTR_ERR(alist) == -EINTR) && 648 (op->flags & AFS_OPERATION_UNINTR) && 649 has_addrs) { 650 _leave(" = t [intr]"); 651 return true; 652 } 653 afs_op_set_error(op, PTR_ERR(alist)); 654 _leave(" = f [%d]", afs_op_error(op)); 655 return false; 656 } 657 658 if (server->addr_version != alist->version) 659 afs_fs_probe_fileserver(op->net, server, alist, key); 660 661 afs_put_addrlist(alist, afs_alist_trace_put_server_update); 662 _leave(" = t"); 663 return true; 664} 665 666/* 667 * See if a server's address list needs updating. 668 */ 669bool afs_check_server_record(struct afs_operation *op, struct afs_server *server, 670 struct key *key) 671{ 672 bool success; 673 int ret, retries = 0; 674 675 _enter(""); 676 677 ASSERT(server); 678 679retry: 680 if (test_bit(AFS_SERVER_FL_UPDATING, &server->flags)) 681 goto wait; 682 if (test_bit(AFS_SERVER_FL_NEEDS_UPDATE, &server->flags)) 683 goto update; 684 _leave(" = t [good]"); 685 return true; 686 687update: 688 if (!test_and_set_bit_lock(AFS_SERVER_FL_UPDATING, &server->flags)) { 689 clear_bit(AFS_SERVER_FL_NEEDS_UPDATE, &server->flags); 690 success = afs_update_server_record(op, server, key); 691 clear_bit_unlock(AFS_SERVER_FL_UPDATING, &server->flags); 692 wake_up_bit(&server->flags, AFS_SERVER_FL_UPDATING); 693 _leave(" = %d", success); 694 return success; 695 } 696 697wait: 698 ret = wait_on_bit(&server->flags, AFS_SERVER_FL_UPDATING, 699 (op->flags & AFS_OPERATION_UNINTR) ? 700 TASK_UNINTERRUPTIBLE : TASK_INTERRUPTIBLE); 701 if (ret == -ERESTARTSYS) { 702 afs_op_set_error(op, ret); 703 _leave(" = f [intr]"); 704 return false; 705 } 706 707 retries++; 708 if (retries == 4) { 709 _leave(" = f [stale]"); 710 ret = -ESTALE; 711 return false; 712 } 713 goto retry; 714} 715