fs/afs/vl_rotate.c

   1 /* Handle vlserver selection and rotation.
   2  *
   3  * Copyright (C) 2018 Red Hat, Inc. All Rights Reserved.
   4  * Written by David Howells ([email protected])
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public Licence
   8  * as published by the Free Software Foundation; either version
   9  * 2 of the Licence, or (at your option) any later version.
  10  */
  11
  12 #include <linux/kernel.h>
  13 #include <linux/sched.h>
  14 #include <linux/sched/signal.h>
  15 #include "internal.h"
  16 #include "afs_vl.h"
  17
  18 /*
  19  * Begin an operation on a volume location server.
  20  */
  21 bool afs_begin_vlserver_operation(struct afs_vl_cursor *vc, struct afs_cell *cell,
  22                                   struct key *key)
  23 {
  24         memset(vc, 0, sizeof(*vc));
  25         vc->cell = cell;
  26         vc->key = key;
  27         vc->error = -EDESTADDRREQ;
  28         vc->ac.error = SHRT_MAX;
  29
  30         if (signal_pending(current)) {
  31                 vc->error = -EINTR;
  32                 vc->flags |= AFS_VL_CURSOR_STOP;
  33                 return false;
  34         }
  35
  36         return true;
  37 }
  38
  39 /*
  40  * Begin iteration through a server list, starting with the last used server if
  41  * possible, or the last recorded good server if not.
  42  */
  43 static bool afs_start_vl_iteration(struct afs_vl_cursor *vc)
  44 {
  45         struct afs_cell *cell = vc->cell;
  46
  47         if (wait_on_bit(&cell->flags, AFS_CELL_FL_NO_LOOKUP_YET,
  48                         TASK_INTERRUPTIBLE)) {
  49                 vc->error = -ERESTARTSYS;
  50                 return false;
  51         }
  52
  53         read_lock(&cell->vl_servers_lock);
  54         vc->server_list = afs_get_vlserverlist(
  55                 rcu_dereference_protected(cell->vl_servers,
  56                                           lockdep_is_held(&cell->vl_servers_lock)));
  57         read_unlock(&cell->vl_servers_lock);
  58         if (!vc->server_list || !vc->server_list->nr_servers)
  59                 return false;
  60
  61         vc->untried = (1UL << vc->server_list->nr_servers) - 1;
  62         vc->index = -1;
  63         return true;
  64 }
  65
  66 /*
  67  * Select the vlserver to use.  May be called multiple times to rotate
  68  * through the vlservers.
  69  */
  70 bool afs_select_vlserver(struct afs_vl_cursor *vc)
  71 {
  72         struct afs_addr_list *alist;
  73         struct afs_vlserver *vlserver;
  74         u32 rtt;
  75         int error = vc->ac.error, abort_code, i;
  76
  77         _enter("%lx[%d],%lx[%d],%d,%d",
  78                vc->untried, vc->index,
  79                vc->ac.tried, vc->ac.index,
  80                error, vc->ac.abort_code);
  81
  82         if (vc->flags & AFS_VL_CURSOR_STOP) {
  83                 _leave(" = f [stopped]");
  84                 return false;
  85         }
  86
  87         vc->nr_iterations++;
  88
  89         /* Evaluate the result of the previous operation, if there was one. */
  90         switch (error) {
  91         case SHRT_MAX:
  92                 goto start;
  93
  94         default:
  95         case 0:
  96                 /* Success or local failure.  Stop. */
  97                 vc->error = error;
  98                 vc->flags |= AFS_VL_CURSOR_STOP;
  99                 _leave(" = f [okay/local %d]", vc->ac.error);
 100                 return false;
 101
 102         case -ECONNABORTED:
 103                 /* The far side rejected the operation on some grounds.  This
 104                  * might involve the server being busy or the volume having been moved.
 105                  */
 106                 switch (vc->ac.abort_code) {
 107                 case AFSVL_IO:
 108                 case AFSVL_BADVOLOPER:
 109                 case AFSVL_NOMEM:
 110                         /* The server went weird. */
 111                         vc->error = -EREMOTEIO;
 112                         //write_lock(&vc->cell->vl_servers_lock);
 113                         //vc->server_list->weird_mask |= 1 << vc->index;
 114                         //write_unlock(&vc->cell->vl_servers_lock);
 115                         goto next_server;
 116
 117                 default:
 118                         vc->error = afs_abort_to_error(vc->ac.abort_code);
 119                         goto failed;
 120                 }
 121
 122         case -ENETUNREACH:
 123         case -EHOSTUNREACH:
 124         case -ECONNREFUSED:
 125         case -ETIMEDOUT:
 126         case -ETIME:
 127                 _debug("no conn %d", error);
 128                 vc->error = error;
 129                 goto iterate_address;
 130
 131         case -ECONNRESET:
 132                 _debug("call reset");
 133                 vc->error = error;
 134                 vc->flags |= AFS_VL_CURSOR_RETRY;
 135                 goto next_server;
 136         }
 137
 138 restart_from_beginning:
 139         _debug("restart");
 140         afs_end_cursor(&vc->ac);
 141         afs_put_vlserverlist(vc->cell->net, vc->server_list);
 142         vc->server_list = NULL;
 143         if (vc->flags & AFS_VL_CURSOR_RETRIED)
 144                 goto failed;
 145         vc->flags |= AFS_VL_CURSOR_RETRIED;
 146 start:
 147         _debug("start");
 148
 149         if (!afs_start_vl_iteration(vc))
 150                 goto failed;
 151
 152         error = afs_send_vl_probes(vc->cell->net, vc->key, vc->server_list);
 153         if (error < 0)
 154                 goto failed_set_error;
 155
 156 pick_server:
 157         _debug("pick [%lx]", vc->untried);
 158
 159         error = afs_wait_for_vl_probes(vc->server_list, vc->untried);
 160         if (error < 0)
 161                 goto failed_set_error;
 162
 163         /* Pick the untried server with the lowest RTT. */
 164         vc->index = vc->server_list->preferred;
 165         if (test_bit(vc->index, &vc->untried))
 166                 goto selected_server;
 167
 168         vc->index = -1;
 169         rtt = U32_MAX;
 170         for (i = 0; i < vc->server_list->nr_servers; i++) {
 171                 struct afs_vlserver *s = vc->server_list->servers[i].server;
 172
 173                 if (!test_bit(i, &vc->untried) || !s->probe.responded)
 174                         continue;
 175                 if (s->probe.rtt < rtt) {
 176                         vc->index = i;
 177                         rtt = s->probe.rtt;
 178                 }
 179         }
 180
 181         if (vc->index == -1)
 182                 goto no_more_servers;
 183
 184 selected_server:
 185         _debug("use %d", vc->index);
 186         __clear_bit(vc->index, &vc->untried);
 187
 188         /* We're starting on a different vlserver from the list.  We need to
 189          * check it, find its address list and probe its capabilities before we
 190          * use it.
 191          */
 192         ASSERTCMP(vc->ac.alist, ==, NULL);
 193         vlserver = vc->server_list->servers[vc->index].server;
 194         vc->server = vlserver;
 195
 196         _debug("USING VLSERVER: %s", vlserver->name);
 197
 198         read_lock(&vlserver->lock);
 199         alist = rcu_dereference_protected(vlserver->addresses,
 200                                           lockdep_is_held(&vlserver->lock));
 201         afs_get_addrlist(alist);
 202         read_unlock(&vlserver->lock);
 203
 204         memset(&vc->ac, 0, sizeof(vc->ac));
 205
 206         if (!vc->ac.alist)
 207                 vc->ac.alist = alist;
 208         else
 209                 afs_put_addrlist(alist);
 210
 211         vc->ac.index = -1;
 212
 213 iterate_address:
 214         ASSERT(vc->ac.alist);
 215         /* Iterate over the current server's address list to try and find an
 216          * address on which it will respond to us.
 217          */
 218         if (!afs_iterate_addresses(&vc->ac))
 219                 goto next_server;
 220
 221         _debug("VL address %d/%d", vc->ac.index, vc->ac.alist->nr_addrs);
 222
 223         _leave(" = t %pISpc", &vc->ac.alist->addrs[vc->ac.index].transport);
 224         return true;
 225
 226 next_server:
 227         _debug("next");
 228         afs_end_cursor(&vc->ac);
 229         goto pick_server;
 230
 231 no_more_servers:
 232         /* That's all the servers poked to no good effect.  Try again if some
 233          * of them were busy.
 234          */
 235         if (vc->flags & AFS_VL_CURSOR_RETRY)
 236                 goto restart_from_beginning;
 237
 238         abort_code = 0;
 239         error = -EDESTADDRREQ;
 240         for (i = 0; i < vc->server_list->nr_servers; i++) {
 241                 struct afs_vlserver *s = vc->server_list->servers[i].server;
 242                 int probe_error = READ_ONCE(s->probe.error);
 243
 244                 switch (probe_error) {
 245                 case 0:
 246                         continue;
 247                 default:
 248                         if (error == -ETIMEDOUT ||
 249                             error == -ETIME)
 250                                 continue;
 251                 case -ETIMEDOUT:
 252                 case -ETIME:
 253                         if (error == -ENOMEM ||
 254                             error == -ENONET)
 255                                 continue;
 256                 case -ENOMEM:
 257                 case -ENONET:
 258                         if (error == -ENETUNREACH)
 259                                 continue;
 260                 case -ENETUNREACH:
 261                         if (error == -EHOSTUNREACH)
 262                                 continue;
 263                 case -EHOSTUNREACH:
 264                         if (error == -ECONNREFUSED)
 265                                 continue;
 266                 case -ECONNREFUSED:
 267                         if (error == -ECONNRESET)
 268                                 continue;
 269                 case -ECONNRESET: /* Responded, but call expired. */
 270                         if (error == -ECONNABORTED)
 271                                 continue;
 272                 case -ECONNABORTED:
 273                         abort_code = s->probe.abort_code;
 274                         error = probe_error;
 275                         continue;
 276                 }
 277         }
 278
 279         if (error == -ECONNABORTED)
 280                 error = afs_abort_to_error(abort_code);
 281
 282 failed_set_error:
 283         vc->error = error;
 284 failed:
 285         vc->flags |= AFS_VL_CURSOR_STOP;
 286         afs_end_cursor(&vc->ac);
 287         _leave(" = f [failed %d]", vc->error);
 288         return false;
 289 }
 290
 291 /*
 292  * Dump cursor state in the case of the error being EDESTADDRREQ.
 293  */
 294 static void afs_vl_dump_edestaddrreq(const struct afs_vl_cursor *vc)
 295 {
 296         static int count;
 297         int i;
 298
 299         if (!IS_ENABLED(CONFIG_AFS_DEBUG_CURSOR) || count > 3)
 300                 return;
 301         count++;
 302
 303         rcu_read_lock();
 304         pr_notice("EDESTADDR occurred\n");
 305         pr_notice("VC: ut=%lx ix=%u ni=%hu fl=%hx err=%hd\n",
 306                   vc->untried, vc->index, vc->nr_iterations, vc->flags, vc->error);
 307
 308         if (vc->server_list) {
 309                 const struct afs_vlserver_list *sl = vc->server_list;
 310                 pr_notice("VC: SL nr=%u ix=%u\n",
 311                           sl->nr_servers, sl->index);
 312                 for (i = 0; i < sl->nr_servers; i++) {
 313                         const struct afs_vlserver *s = sl->servers[i].server;
 314                         pr_notice("VC: server %s+%hu fl=%lx E=%hd\n",
 315                                   s->name, s->port, s->flags, s->probe.error);
 316                         if (s->addresses) {
 317                                 const struct afs_addr_list *a =
 318                                         rcu_dereference(s->addresses);
 319                                 pr_notice("VC:  - nr=%u/%u/%u pf=%u\n",
 320                                           a->nr_ipv4, a->nr_addrs, a->max_addrs,
 321                                           a->preferred);
 322                                 pr_notice("VC:  - pr=%lx R=%lx F=%lx\n",
 323                                           a->probed, a->responded, a->failed);
 324                                 if (a == vc->ac.alist)
 325                                         pr_notice("VC:  - current\n");
 326                         }
 327                 }
 328         }
 329
 330         pr_notice("AC: t=%lx ax=%u ac=%d er=%d r=%u ni=%u\n",
 331                   vc->ac.tried, vc->ac.index, vc->ac.abort_code, vc->ac.error,
 332                   vc->ac.responded, vc->ac.nr_iterations);
 333         rcu_read_unlock();
 334 }
 335
 336 /*
 337  * Tidy up a volume location server cursor and unlock the vnode.
 338  */
 339 int afs_end_vlserver_operation(struct afs_vl_cursor *vc)
 340 {
 341         struct afs_net *net = vc->cell->net;
 342
 343         if (vc->error == -EDESTADDRREQ ||
 344             vc->error == -ENETUNREACH ||
 345             vc->error == -EHOSTUNREACH)
 346                 afs_vl_dump_edestaddrreq(vc);
 347
 348         afs_end_cursor(&vc->ac);
 349         afs_put_vlserverlist(net, vc->server_list);
 350
 351         if (vc->error == -ECONNABORTED)
 352                 vc->error = afs_abort_to_error(vc->ac.abort_code);
 353
 354         return vc->error;
 355 }