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