fs/afs/fs_probe.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /* AFS fileserver probing
   3  *
   4  * Copyright (C) 2018, 2020 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_afs.h"
  13 #include "protocol_yfs.h"
  14
  15 static unsigned int afs_fs_probe_fast_poll_interval = 30 * HZ;
  16 static unsigned int afs_fs_probe_slow_poll_interval = 5 * 60 * HZ;
  17
  18 struct afs_endpoint_state *afs_get_endpoint_state(struct afs_endpoint_state *estate,
  19                                                   enum afs_estate_trace where)
  20 {
  21         if (estate) {
  22                 int r;
  23
  24                 __refcount_inc(&estate->ref, &r);
  25                 trace_afs_estate(estate->server_id, estate->probe_seq, r, where);
  26         }
  27         return estate;
  28 }
  29
  30 static void afs_endpoint_state_rcu(struct rcu_head *rcu)
  31 {
  32         struct afs_endpoint_state *estate = container_of(rcu, struct afs_endpoint_state, rcu);
  33
  34         trace_afs_estate(estate->server_id, estate->probe_seq, refcount_read(&estate->ref),
  35                          afs_estate_trace_free);
  36         afs_put_addrlist(estate->addresses, afs_alist_trace_put_estate);
  37         kfree(estate);
  38 }
  39
  40 void afs_put_endpoint_state(struct afs_endpoint_state *estate, enum afs_estate_trace where)
  41 {
  42         if (estate) {
  43                 unsigned int server_id = estate->server_id, probe_seq = estate->probe_seq;
  44                 bool dead;
  45                 int r;
  46
  47                 dead = __refcount_dec_and_test(&estate->ref, &r);
  48                 trace_afs_estate(server_id, probe_seq, r, where);
  49                 if (dead)
  50                         call_rcu(&estate->rcu, afs_endpoint_state_rcu);
  51         }
  52 }
  53
  54 /*
  55  * Start the probe polling timer.  We have to supply it with an inc on the
  56  * outstanding server count.
  57  */
  58 static void afs_schedule_fs_probe(struct afs_net *net,
  59                                   struct afs_server *server, bool fast)
  60 {
  61         unsigned long atj;
  62
  63         if (!net->live)
  64                 return;
  65
  66         atj = server->probed_at;
  67         atj += fast ? afs_fs_probe_fast_poll_interval : afs_fs_probe_slow_poll_interval;
  68
  69         afs_inc_servers_outstanding(net);
  70         if (timer_reduce(&net->fs_probe_timer, atj))
  71                 afs_dec_servers_outstanding(net);
  72 }
  73
  74 /*
  75  * Handle the completion of a set of probes.
  76  */
  77 static void afs_finished_fs_probe(struct afs_net *net, struct afs_server *server,
  78                                   struct afs_endpoint_state *estate)
  79 {
  80         bool responded = test_bit(AFS_ESTATE_RESPONDED, &estate->flags);
  81
  82         write_seqlock(&net->fs_lock);
  83         if (responded) {
  84                 list_add_tail(&server->probe_link, &net->fs_probe_slow);
  85         } else {
  86                 server->rtt = UINT_MAX;
  87                 clear_bit(AFS_SERVER_FL_RESPONDING, &server->flags);
  88                 list_add_tail(&server->probe_link, &net->fs_probe_fast);
  89         }
  90
  91         write_sequnlock(&net->fs_lock);
  92
  93         afs_schedule_fs_probe(net, server, !responded);
  94 }
  95
  96 /*
  97  * Handle the completion of a probe.
  98  */
  99 static void afs_done_one_fs_probe(struct afs_net *net, struct afs_server *server,
 100                                   struct afs_endpoint_state *estate)
 101 {
 102         _enter("");
 103
 104         if (atomic_dec_and_test(&estate->nr_probing))
 105                 afs_finished_fs_probe(net, server, estate);
 106
 107         wake_up_all(&server->probe_wq);
 108 }
 109
 110 /*
 111  * Handle inability to send a probe due to ENOMEM when trying to allocate a
 112  * call struct.
 113  */
 114 static void afs_fs_probe_not_done(struct afs_net *net,
 115                                   struct afs_server *server,
 116                                   struct afs_endpoint_state *estate,
 117                                   int index)
 118 {
 119         _enter("");
 120
 121         trace_afs_io_error(0, -ENOMEM, afs_io_error_fs_probe_fail);
 122         spin_lock(&server->probe_lock);
 123
 124         set_bit(AFS_ESTATE_LOCAL_FAILURE, &estate->flags);
 125         if (estate->error == 0)
 126                 estate->error = -ENOMEM;
 127
 128         set_bit(index, &estate->failed_set);
 129
 130         spin_unlock(&server->probe_lock);
 131         return afs_done_one_fs_probe(net, server, estate);
 132 }
 133
 134 /*
 135  * Process the result of probing a fileserver.  This is called after successful
 136  * or failed delivery of an FS.GetCapabilities operation.
 137  */
 138 void afs_fileserver_probe_result(struct afs_call *call)
 139 {
 140         struct afs_endpoint_state *estate = call->probe;
 141         struct afs_addr_list *alist = estate->addresses;
 142         struct afs_address *addr = &alist->addrs[call->probe_index];
 143         struct afs_server *server = call->server;
 144         unsigned int index = call->probe_index;
 145         unsigned int rtt_us = -1, cap0;
 146         int ret = call->error;
 147
 148         _enter("%pU,%u", &server->uuid, index);
 149
 150         WRITE_ONCE(addr->last_error, ret);
 151
 152         spin_lock(&server->probe_lock);
 153
 154         switch (ret) {
 155         case 0:
 156                 estate->error = 0;
 157                 goto responded;
 158         case -ECONNABORTED:
 159                 if (!test_bit(AFS_ESTATE_RESPONDED, &estate->flags)) {
 160                         estate->abort_code = call->abort_code;
 161                         estate->error = ret;
 162                 }
 163                 goto responded;
 164         case -ENOMEM:
 165         case -ENONET:
 166                 clear_bit(index, &estate->responsive_set);
 167                 set_bit(AFS_ESTATE_LOCAL_FAILURE, &estate->flags);
 168                 trace_afs_io_error(call->debug_id, ret, afs_io_error_fs_probe_fail);
 169                 goto out;
 170         case -ECONNRESET: /* Responded, but call expired. */
 171         case -ERFKILL:
 172         case -EADDRNOTAVAIL:
 173         case -ENETUNREACH:
 174         case -EHOSTUNREACH:
 175         case -EHOSTDOWN:
 176         case -ECONNREFUSED:
 177         case -ETIMEDOUT:
 178         case -ETIME:
 179         default:
 180                 clear_bit(index, &estate->responsive_set);
 181                 set_bit(index, &estate->failed_set);
 182                 if (!test_bit(AFS_ESTATE_RESPONDED, &estate->flags) &&
 183                     (estate->error == 0 ||
 184                      estate->error == -ETIMEDOUT ||
 185                      estate->error == -ETIME))
 186                         estate->error = ret;
 187                 trace_afs_io_error(call->debug_id, ret, afs_io_error_fs_probe_fail);
 188                 goto out;
 189         }
 190
 191 responded:
 192         clear_bit(index, &estate->failed_set);
 193
 194         if (call->service_id == YFS_FS_SERVICE) {
 195                 set_bit(AFS_ESTATE_IS_YFS, &estate->flags);
 196                 set_bit(AFS_SERVER_FL_IS_YFS, &server->flags);
 197                 server->service_id = call->service_id;
 198         } else {
 199                 set_bit(AFS_ESTATE_NOT_YFS, &estate->flags);
 200                 if (!test_bit(AFS_ESTATE_IS_YFS, &estate->flags)) {
 201                         clear_bit(AFS_SERVER_FL_IS_YFS, &server->flags);
 202                         server->service_id = call->service_id;
 203                 }
 204                 cap0 = ntohl(call->tmp);
 205                 if (cap0 & AFS3_VICED_CAPABILITY_64BITFILES)
 206                         set_bit(AFS_SERVER_FL_HAS_FS64, &server->flags);
 207                 else
 208                         clear_bit(AFS_SERVER_FL_HAS_FS64, &server->flags);
 209         }
 210
 211         rtt_us = rxrpc_kernel_get_srtt(addr->peer);
 212         if (rtt_us < estate->rtt) {
 213                 estate->rtt = rtt_us;
 214                 server->rtt = rtt_us;
 215                 alist->preferred = index;
 216         }
 217
 218         smp_wmb(); /* Set rtt before responded. */
 219         set_bit(AFS_ESTATE_RESPONDED, &estate->flags);
 220         set_bit(index, &estate->responsive_set);
 221         set_bit(AFS_SERVER_FL_RESPONDING, &server->flags);
 222 out:
 223         spin_unlock(&server->probe_lock);
 224
 225         trace_afs_fs_probe(server, false, estate, index, call->error, call->abort_code, rtt_us);
 226         _debug("probe[%x] %pU [%u] %pISpc rtt=%d ret=%d",
 227                estate->probe_seq, &server->uuid, index,
 228                rxrpc_kernel_remote_addr(alist->addrs[index].peer),
 229                rtt_us, ret);
 230
 231         return afs_done_one_fs_probe(call->net, server, estate);
 232 }
 233
 234 /*
 235  * Probe all of a fileserver's addresses to find out the best route and to
 236  * query its capabilities.
 237  */
 238 void afs_fs_probe_fileserver(struct afs_net *net, struct afs_server *server,
 239                              struct afs_addr_list *new_alist, struct key *key)
 240 {
 241         struct afs_endpoint_state *estate, *old;
 242         struct afs_addr_list *alist;
 243         unsigned long unprobed;
 244
 245         _enter("%pU", &server->uuid);
 246
 247         estate = kzalloc(sizeof(*estate), GFP_KERNEL);
 248         if (!estate)
 249                 return;
 250
 251         refcount_set(&estate->ref, 1);
 252         estate->server_id = server->debug_id;
 253         estate->rtt = UINT_MAX;
 254
 255         write_lock(&server->fs_lock);
 256
 257         old = rcu_dereference_protected(server->endpoint_state,
 258                                         lockdep_is_held(&server->fs_lock));
 259         estate->responsive_set = old->responsive_set;
 260         estate->addresses = afs_get_addrlist(new_alist ?: old->addresses,
 261                                              afs_alist_trace_get_estate);
 262         alist = estate->addresses;
 263         estate->probe_seq = ++server->probe_counter;
 264         atomic_set(&estate->nr_probing, alist->nr_addrs);
 265
 266         rcu_assign_pointer(server->endpoint_state, estate);
 267         set_bit(AFS_ESTATE_SUPERSEDED, &old->flags);
 268         write_unlock(&server->fs_lock);
 269
 270         trace_afs_estate(estate->server_id, estate->probe_seq, refcount_read(&estate->ref),
 271                          afs_estate_trace_alloc_probe);
 272
 273         afs_get_address_preferences(net, alist);
 274
 275         server->probed_at = jiffies;
 276         unprobed = (1UL << alist->nr_addrs) - 1;
 277         while (unprobed) {
 278                 unsigned int index = 0, i;
 279                 int best_prio = -1;
 280
 281                 for (i = 0; i < alist->nr_addrs; i++) {
 282                         if (test_bit(i, &unprobed) &&
 283                             alist->addrs[i].prio > best_prio) {
 284                                 index = i;
 285                                 best_prio = alist->addrs[i].prio;
 286                         }
 287                 }
 288                 __clear_bit(index, &unprobed);
 289
 290                 trace_afs_fs_probe(server, true, estate, index, 0, 0, 0);
 291                 if (!afs_fs_get_capabilities(net, server, estate, index, key))
 292                         afs_fs_probe_not_done(net, server, estate, index);
 293         }
 294
 295         afs_put_endpoint_state(old, afs_estate_trace_put_probe);
 296 }
 297
 298 /*
 299  * Wait for the first as-yet untried fileserver to respond, for the probe state
 300  * to be superseded or for all probes to finish.
 301  */
 302 int afs_wait_for_fs_probes(struct afs_operation *op, struct afs_server_state *states, bool intr)
 303 {
 304         struct afs_endpoint_state *estate;
 305         struct afs_server_list *slist = op->server_list;
 306         bool still_probing = true;
 307         int ret = 0, i;
 308
 309         _enter("%u", slist->nr_servers);
 310
 311         for (i = 0; i < slist->nr_servers; i++) {
 312                 estate = states[i].endpoint_state;
 313                 if (test_bit(AFS_ESTATE_SUPERSEDED, &estate->flags))
 314                         return 2;
 315                 if (atomic_read(&estate->nr_probing))
 316                         still_probing = true;
 317                 if (estate->responsive_set & states[i].untried_addrs)
 318                         return 1;
 319         }
 320         if (!still_probing)
 321                 return 0;
 322
 323         for (i = 0; i < slist->nr_servers; i++)
 324                 add_wait_queue(&slist->servers[i].server->probe_wq, &states[i].probe_waiter);
 325
 326         for (;;) {
 327                 still_probing = false;
 328
 329                 set_current_state(intr ? TASK_INTERRUPTIBLE : TASK_UNINTERRUPTIBLE);
 330                 for (i = 0; i < slist->nr_servers; i++) {
 331                         estate = states[i].endpoint_state;
 332                         if (test_bit(AFS_ESTATE_SUPERSEDED, &estate->flags)) {
 333                                 ret = 2;
 334                                 goto stop;
 335                         }
 336                         if (atomic_read(&estate->nr_probing))
 337                                 still_probing = true;
 338                         if (estate->responsive_set & states[i].untried_addrs) {
 339                                 ret = 1;
 340                                 goto stop;
 341                         }
 342                 }
 343
 344                 if (!still_probing || signal_pending(current))
 345                         goto stop;
 346                 schedule();
 347         }
 348
 349 stop:
 350         set_current_state(TASK_RUNNING);
 351
 352         for (i = 0; i < slist->nr_servers; i++)
 353                 remove_wait_queue(&slist->servers[i].server->probe_wq, &states[i].probe_waiter);
 354
 355         if (!ret && signal_pending(current))
 356                 ret = -ERESTARTSYS;
 357         return ret;
 358 }
 359
 360 /*
 361  * Probe timer.  We have an increment on fs_outstanding that we need to pass
 362  * along to the work item.
 363  */
 364 void afs_fs_probe_timer(struct timer_list *timer)
 365 {
 366         struct afs_net *net = container_of(timer, struct afs_net, fs_probe_timer);
 367
 368         if (!net->live || !queue_work(afs_wq, &net->fs_prober))
 369                 afs_dec_servers_outstanding(net);
 370 }
 371
 372 /*
 373  * Dispatch a probe to a server.
 374  */
 375 static void afs_dispatch_fs_probe(struct afs_net *net, struct afs_server *server)
 376         __releases(&net->fs_lock)
 377 {
 378         struct key *key = NULL;
 379
 380         /* We remove it from the queues here - it will be added back to
 381          * one of the queues on the completion of the probe.
 382          */
 383         list_del_init(&server->probe_link);
 384
 385         afs_get_server(server, afs_server_trace_get_probe);
 386         write_sequnlock(&net->fs_lock);
 387
 388         afs_fs_probe_fileserver(net, server, NULL, key);
 389         afs_put_server(net, server, afs_server_trace_put_probe);
 390 }
 391
 392 /*
 393  * Probe a server immediately without waiting for its due time to come
 394  * round.  This is used when all of the addresses have been tried.
 395  */
 396 void afs_probe_fileserver(struct afs_net *net, struct afs_server *server)
 397 {
 398         write_seqlock(&net->fs_lock);
 399         if (!list_empty(&server->probe_link))
 400                 return afs_dispatch_fs_probe(net, server);
 401         write_sequnlock(&net->fs_lock);
 402 }
 403
 404 /*
 405  * Probe dispatcher to regularly dispatch probes to keep NAT alive.
 406  */
 407 void afs_fs_probe_dispatcher(struct work_struct *work)
 408 {
 409         struct afs_net *net = container_of(work, struct afs_net, fs_prober);
 410         struct afs_server *fast, *slow, *server;
 411         unsigned long nowj, timer_at, poll_at;
 412         bool first_pass = true, set_timer = false;
 413
 414         if (!net->live) {
 415                 afs_dec_servers_outstanding(net);
 416                 return;
 417         }
 418
 419         _enter("");
 420
 421         if (list_empty(&net->fs_probe_fast) && list_empty(&net->fs_probe_slow)) {
 422                 afs_dec_servers_outstanding(net);
 423                 _leave(" [none]");
 424                 return;
 425         }
 426
 427 again:
 428         write_seqlock(&net->fs_lock);
 429
 430         fast = slow = server = NULL;
 431         nowj = jiffies;
 432         timer_at = nowj + MAX_JIFFY_OFFSET;
 433
 434         if (!list_empty(&net->fs_probe_fast)) {
 435                 fast = list_first_entry(&net->fs_probe_fast, struct afs_server, probe_link);
 436                 poll_at = fast->probed_at + afs_fs_probe_fast_poll_interval;
 437                 if (time_before(nowj, poll_at)) {
 438                         timer_at = poll_at;
 439                         set_timer = true;
 440                         fast = NULL;
 441                 }
 442         }
 443
 444         if (!list_empty(&net->fs_probe_slow)) {
 445                 slow = list_first_entry(&net->fs_probe_slow, struct afs_server, probe_link);
 446                 poll_at = slow->probed_at + afs_fs_probe_slow_poll_interval;
 447                 if (time_before(nowj, poll_at)) {
 448                         if (time_before(poll_at, timer_at))
 449                             timer_at = poll_at;
 450                         set_timer = true;
 451                         slow = NULL;
 452                 }
 453         }
 454
 455         server = fast ?: slow;
 456         if (server)
 457                 _debug("probe %pU", &server->uuid);
 458
 459         if (server && (first_pass || !need_resched())) {
 460                 afs_dispatch_fs_probe(net, server);
 461                 first_pass = false;
 462                 goto again;
 463         }
 464
 465         write_sequnlock(&net->fs_lock);
 466
 467         if (server) {
 468                 if (!queue_work(afs_wq, &net->fs_prober))
 469                         afs_dec_servers_outstanding(net);
 470                 _leave(" [requeue]");
 471         } else if (set_timer) {
 472                 if (timer_reduce(&net->fs_probe_timer, timer_at))
 473                         afs_dec_servers_outstanding(net);
 474                 _leave(" [timer]");
 475         } else {
 476                 afs_dec_servers_outstanding(net);
 477                 _leave(" [quiesce]");
 478         }
 479 }
 480
 481 /*
 482  * Wait for a probe on a particular fileserver to complete for 2s.
 483  */
 484 int afs_wait_for_one_fs_probe(struct afs_server *server, struct afs_endpoint_state *estate,
 485                               unsigned long exclude, bool is_intr)
 486 {
 487         struct wait_queue_entry wait;
 488         unsigned long timo = 2 * HZ;
 489
 490         if (atomic_read(&estate->nr_probing) == 0)
 491                 goto dont_wait;
 492
 493         init_wait_entry(&wait, 0);
 494         for (;;) {
 495                 prepare_to_wait_event(&server->probe_wq, &wait,
 496                                       is_intr ? TASK_INTERRUPTIBLE : TASK_UNINTERRUPTIBLE);
 497                 if (timo == 0 ||
 498                     test_bit(AFS_ESTATE_SUPERSEDED, &estate->flags) ||
 499                     (estate->responsive_set & ~exclude) ||
 500                     atomic_read(&estate->nr_probing) == 0 ||
 501                     (is_intr && signal_pending(current)))
 502                         break;
 503                 timo = schedule_timeout(timo);
 504         }
 505
 506         finish_wait(&server->probe_wq, &wait);
 507
 508 dont_wait:
 509         if (estate->responsive_set & ~exclude)
 510                 return 1;
 511         if (test_bit(AFS_ESTATE_SUPERSEDED, &estate->flags))
 512                 return 0;
 513         if (is_intr && signal_pending(current))
 514                 return -ERESTARTSYS;
 515         if (timo == 0)
 516                 return -ETIME;
 517         return -EDESTADDRREQ;
 518 }
 519
 520 /*
 521  * Clean up the probing when the namespace is killed off.
 522  */
 523 void afs_fs_probe_cleanup(struct afs_net *net)
 524 {
 525         if (del_timer_sync(&net->fs_probe_timer))
 526                 afs_dec_servers_outstanding(net);
 527 }