fs/afs/vl_rotate.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /* Handle vlserver selection and rotation.
   3  *
   4  * Copyright (C) 2018 Red Hat, Inc. All Rights Reserved.
   5  * Written by David Howells ([email protected])
   6  */
   7
   8 #include <linux/kernel.h>
   9 #include <linux/sched.h>
  10 #include <linux/sched/signal.h>
  11 #include "internal.h"
  12 #include "afs_vl.h"
  13
  14 /*
  15  * Begin an operation on a volume location server.
  16  */
  17 bool afs_begin_vlserver_operation(struct afs_vl_cursor *vc, struct afs_cell *cell,
  18                                   struct key *key)
  19 {
  20         memset(vc, 0, sizeof(*vc));
  21         vc->cell = cell;
  22         vc->key = key;
  23         vc->error = -EDESTADDRREQ;
  24         vc->ac.error = SHRT_MAX;
  25
  26         if (signal_pending(current)) {
  27                 vc->error = -EINTR;
  28                 vc->flags |= AFS_VL_CURSOR_STOP;
  29                 return false;
  30         }
  31
  32         return true;
  33 }
  34
  35 /*
  36  * Begin iteration through a server list, starting with the last used server if
  37  * possible, or the last recorded good server if not.
  38  */
  39 static bool afs_start_vl_iteration(struct afs_vl_cursor *vc)
  40 {
  41         struct afs_cell *cell = vc->cell;
  42         unsigned int dns_lookup_count;
  43
  44         if (cell->dns_source == DNS_RECORD_UNAVAILABLE ||
  45             cell->dns_expiry <= ktime_get_real_seconds()) {
  46                 dns_lookup_count = smp_load_acquire(&cell->dns_lookup_count);
  47                 set_bit(AFS_CELL_FL_DO_LOOKUP, &cell->flags);
  48                 afs_queue_cell(cell, afs_cell_trace_get_queue_dns);
  49
  50                 if (cell->dns_source == DNS_RECORD_UNAVAILABLE) {
  51                         if (wait_var_event_interruptible(
  52                                     &cell->dns_lookup_count,
  53                                     smp_load_acquire(&cell->dns_lookup_count)
  54                                     != dns_lookup_count) < 0) {
  55                                 vc->error = -ERESTARTSYS;
  56                                 return false;
  57                         }
  58                 }
  59
  60                 /* Status load is ordered after lookup counter load */
  61                 if (cell->dns_status == DNS_LOOKUP_GOT_NOT_FOUND) {
  62                         pr_warn("No record of cell %s\n", cell->name);
  63                         vc->error = -ENOENT;
  64                         return false;
  65                 }
  66
  67                 if (cell->dns_source == DNS_RECORD_UNAVAILABLE) {
  68                         vc->error = -EDESTADDRREQ;
  69                         return false;
  70                 }
  71         }
  72
  73         read_lock(&cell->vl_servers_lock);
  74         vc->server_list = afs_get_vlserverlist(
  75                 rcu_dereference_protected(cell->vl_servers,
  76                                           lockdep_is_held(&cell->vl_servers_lock)));
  77         read_unlock(&cell->vl_servers_lock);
  78         if (!vc->server_list->nr_servers)
  79                 return false;
  80
  81         vc->untried = (1UL << vc->server_list->nr_servers) - 1;
  82         vc->index = -1;
  83         return true;
  84 }
  85
  86 /*
  87  * Select the vlserver to use.  May be called multiple times to rotate
  88  * through the vlservers.
  89  */
  90 bool afs_select_vlserver(struct afs_vl_cursor *vc)
  91 {
  92         struct afs_addr_list *alist;
  93         struct afs_vlserver *vlserver;
  94         struct afs_error e;
  95         u32 rtt;
  96         int error = vc->ac.error, i;
  97
  98         _enter("%lx[%d],%lx[%d],%d,%d",
  99                vc->untried, vc->index,
 100                vc->ac.tried, vc->ac.index,
 101                error, vc->ac.abort_code);
 102
 103         if (vc->flags & AFS_VL_CURSOR_STOP) {
 104                 _leave(" = f [stopped]");
 105                 return false;
 106         }
 107
 108         vc->nr_iterations++;
 109
 110         /* Evaluate the result of the previous operation, if there was one. */
 111         switch (error) {
 112         case SHRT_MAX:
 113                 goto start;
 114
 115         default:
 116         case 0:
 117                 /* Success or local failure.  Stop. */
 118                 vc->error = error;
 119                 vc->flags |= AFS_VL_CURSOR_STOP;
 120                 _leave(" = f [okay/local %d]", vc->ac.error);
 121                 return false;
 122
 123         case -ECONNABORTED:
 124                 /* The far side rejected the operation on some grounds.  This
 125                  * might involve the server being busy or the volume having been moved.
 126                  */
 127                 switch (vc->ac.abort_code) {
 128                 case AFSVL_IO:
 129                 case AFSVL_BADVOLOPER:
 130                 case AFSVL_NOMEM:
 131                         /* The server went weird. */
 132                         vc->error = -EREMOTEIO;
 133                         //write_lock(&vc->cell->vl_servers_lock);
 134                         //vc->server_list->weird_mask |= 1 << vc->index;
 135                         //write_unlock(&vc->cell->vl_servers_lock);
 136                         goto next_server;
 137
 138                 default:
 139                         vc->error = afs_abort_to_error(vc->ac.abort_code);
 140                         goto failed;
 141                 }
 142
 143         case -ERFKILL:
 144         case -EADDRNOTAVAIL:
 145         case -ENETUNREACH:
 146         case -EHOSTUNREACH:
 147         case -EHOSTDOWN:
 148         case -ECONNREFUSED:
 149         case -ETIMEDOUT:
 150         case -ETIME:
 151                 _debug("no conn %d", error);
 152                 vc->error = error;
 153                 goto iterate_address;
 154
 155         case -ECONNRESET:
 156                 _debug("call reset");
 157                 vc->error = error;
 158                 vc->flags |= AFS_VL_CURSOR_RETRY;
 159                 goto next_server;
 160
 161         case -EOPNOTSUPP:
 162                 _debug("notsupp");
 163                 goto next_server;
 164         }
 165
 166 restart_from_beginning:
 167         _debug("restart");
 168         afs_end_cursor(&vc->ac);
 169         afs_put_vlserverlist(vc->cell->net, vc->server_list);
 170         vc->server_list = NULL;
 171         if (vc->flags & AFS_VL_CURSOR_RETRIED)
 172                 goto failed;
 173         vc->flags |= AFS_VL_CURSOR_RETRIED;
 174 start:
 175         _debug("start");
 176
 177         if (!afs_start_vl_iteration(vc))
 178                 goto failed;
 179
 180         error = afs_send_vl_probes(vc->cell->net, vc->key, vc->server_list);
 181         if (error < 0)
 182                 goto failed_set_error;
 183
 184 pick_server:
 185         _debug("pick [%lx]", vc->untried);
 186
 187         error = afs_wait_for_vl_probes(vc->server_list, vc->untried);
 188         if (error < 0)
 189                 goto failed_set_error;
 190
 191         /* Pick the untried server with the lowest RTT. */
 192         vc->index = vc->server_list->preferred;
 193         if (test_bit(vc->index, &vc->untried))
 194                 goto selected_server;
 195
 196         vc->index = -1;
 197         rtt = U32_MAX;
 198         for (i = 0; i < vc->server_list->nr_servers; i++) {
 199                 struct afs_vlserver *s = vc->server_list->servers[i].server;
 200
 201                 if (!test_bit(i, &vc->untried) ||
 202                     !test_bit(AFS_VLSERVER_FL_RESPONDING, &s->flags))
 203                         continue;
 204                 if (s->probe.rtt < rtt) {
 205                         vc->index = i;
 206                         rtt = s->probe.rtt;
 207                 }
 208         }
 209
 210         if (vc->index == -1)
 211                 goto no_more_servers;
 212
 213 selected_server:
 214         _debug("use %d", vc->index);
 215         __clear_bit(vc->index, &vc->untried);
 216
 217         /* We're starting on a different vlserver from the list.  We need to
 218          * check it, find its address list and probe its capabilities before we
 219          * use it.
 220          */
 221         ASSERTCMP(vc->ac.alist, ==, NULL);
 222         vlserver = vc->server_list->servers[vc->index].server;
 223         vc->server = vlserver;
 224
 225         _debug("USING VLSERVER: %s", vlserver->name);
 226
 227         read_lock(&vlserver->lock);
 228         alist = rcu_dereference_protected(vlserver->addresses,
 229                                           lockdep_is_held(&vlserver->lock));
 230         afs_get_addrlist(alist);
 231         read_unlock(&vlserver->lock);
 232
 233         memset(&vc->ac, 0, sizeof(vc->ac));
 234
 235         if (!vc->ac.alist)
 236                 vc->ac.alist = alist;
 237         else
 238                 afs_put_addrlist(alist);
 239
 240         vc->ac.index = -1;
 241
 242 iterate_address:
 243         ASSERT(vc->ac.alist);
 244         /* Iterate over the current server's address list to try and find an
 245          * address on which it will respond to us.
 246          */
 247         if (!afs_iterate_addresses(&vc->ac))
 248                 goto next_server;
 249
 250         _debug("VL address %d/%d", vc->ac.index, vc->ac.alist->nr_addrs);
 251
 252         _leave(" = t %pISpc", &vc->ac.alist->addrs[vc->ac.index].transport);
 253         return true;
 254
 255 next_server:
 256         _debug("next");
 257         afs_end_cursor(&vc->ac);
 258         goto pick_server;
 259
 260 no_more_servers:
 261         /* That's all the servers poked to no good effect.  Try again if some
 262          * of them were busy.
 263          */
 264         if (vc->flags & AFS_VL_CURSOR_RETRY)
 265                 goto restart_from_beginning;
 266
 267         e.error = -EDESTADDRREQ;
 268         e.responded = false;
 269         for (i = 0; i < vc->server_list->nr_servers; i++) {
 270                 struct afs_vlserver *s = vc->server_list->servers[i].server;
 271
 272                 if (test_bit(AFS_VLSERVER_FL_RESPONDING, &s->flags))
 273                         e.responded = true;
 274                 afs_prioritise_error(&e, READ_ONCE(s->probe.error),
 275                                      s->probe.abort_code);
 276         }
 277
 278         error = e.error;
 279
 280 failed_set_error:
 281         vc->error = error;
 282 failed:
 283         vc->flags |= AFS_VL_CURSOR_STOP;
 284         afs_end_cursor(&vc->ac);
 285         _leave(" = f [failed %d]", vc->error);
 286         return false;
 287 }
 288
 289 /*
 290  * Dump cursor state in the case of the error being EDESTADDRREQ.
 291  */
 292 static void afs_vl_dump_edestaddrreq(const struct afs_vl_cursor *vc)
 293 {
 294         struct afs_cell *cell = vc->cell;
 295         static int count;
 296         int i;
 297
 298         if (!IS_ENABLED(CONFIG_AFS_DEBUG_CURSOR) || count > 3)
 299                 return;
 300         count++;
 301
 302         rcu_read_lock();
 303         pr_notice("EDESTADDR occurred\n");
 304         pr_notice("CELL: %s err=%d\n", cell->name, cell->error);
 305         pr_notice("DNS: src=%u st=%u lc=%x\n",
 306                   cell->dns_source, cell->dns_status, cell->dns_lookup_count);
 307         pr_notice("VC: ut=%lx ix=%u ni=%hu fl=%hx err=%hd\n",
 308                   vc->untried, vc->index, vc->nr_iterations, vc->flags, vc->error);
 309
 310         if (vc->server_list) {
 311                 const struct afs_vlserver_list *sl = vc->server_list;
 312                 pr_notice("VC: SL nr=%u ix=%u\n",
 313                           sl->nr_servers, sl->index);
 314                 for (i = 0; i < sl->nr_servers; i++) {
 315                         const struct afs_vlserver *s = sl->servers[i].server;
 316                         pr_notice("VC: server %s+%hu fl=%lx E=%hd\n",
 317                                   s->name, s->port, s->flags, s->probe.error);
 318                         if (s->addresses) {
 319                                 const struct afs_addr_list *a =
 320                                         rcu_dereference(s->addresses);
 321                                 pr_notice("VC:  - nr=%u/%u/%u pf=%u\n",
 322                                           a->nr_ipv4, a->nr_addrs, a->max_addrs,
 323                                           a->preferred);
 324                                 pr_notice("VC:  - R=%lx F=%lx\n",
 325                                           a->responded, a->failed);
 326                                 if (a == vc->ac.alist)
 327                                         pr_notice("VC:  - current\n");
 328                         }
 329                 }
 330         }
 331
 332         pr_notice("AC: t=%lx ax=%u ac=%d er=%d r=%u ni=%u\n",
 333                   vc->ac.tried, vc->ac.index, vc->ac.abort_code, vc->ac.error,
 334                   vc->ac.responded, vc->ac.nr_iterations);
 335         rcu_read_unlock();
 336 }
 337
 338 /*
 339  * Tidy up a volume location server cursor and unlock the vnode.
 340  */
 341 int afs_end_vlserver_operation(struct afs_vl_cursor *vc)
 342 {
 343         struct afs_net *net = vc->cell->net;
 344
 345         if (vc->error == -EDESTADDRREQ ||
 346             vc->error == -EADDRNOTAVAIL ||
 347             vc->error == -ENETUNREACH ||
 348             vc->error == -EHOSTUNREACH)
 349                 afs_vl_dump_edestaddrreq(vc);
 350
 351         afs_end_cursor(&vc->ac);
 352         afs_put_vlserverlist(net, vc->server_list);
 353
 354         if (vc->error == -ECONNABORTED)
 355                 vc->error = afs_abort_to_error(vc->ac.abort_code);
 356
 357         return vc->error;
 358 }