fs/afs/vl_probe.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /* AFS vlserver probing
   3  *
   4  * Copyright (C) 2018 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
  14
  15 /*
  16  * Handle the completion of a set of probes.
  17  */
  18 static void afs_finished_vl_probe(struct afs_vlserver *server)
  19 {
  20         if (!(server->probe.flags & AFS_VLSERVER_PROBE_RESPONDED)) {
  21                 server->rtt = UINT_MAX;
  22                 clear_bit(AFS_VLSERVER_FL_RESPONDING, &server->flags);
  23         }
  24
  25         clear_bit_unlock(AFS_VLSERVER_FL_PROBING, &server->flags);
  26         wake_up_bit(&server->flags, AFS_VLSERVER_FL_PROBING);
  27 }
  28
  29 /*
  30  * Handle the completion of a probe RPC call.
  31  */
  32 static void afs_done_one_vl_probe(struct afs_vlserver *server, bool wake_up)
  33 {
  34         if (atomic_dec_and_test(&server->probe_outstanding)) {
  35                 afs_finished_vl_probe(server);
  36                 wake_up = true;
  37         }
  38
  39         if (wake_up)
  40                 wake_up_all(&server->probe_wq);
  41 }
  42
  43 /*
  44  * Process the result of probing a vlserver.  This is called after successful
  45  * or failed delivery of an VL.GetCapabilities operation.
  46  */
  47 void afs_vlserver_probe_result(struct afs_call *call)
  48 {
  49         struct afs_addr_list *alist = call->vl_probe;
  50         struct afs_vlserver *server = call->vlserver;
  51         struct afs_address *addr = &alist->addrs[call->probe_index];
  52         unsigned int server_index = call->server_index;
  53         unsigned int rtt_us = 0;
  54         unsigned int index = call->probe_index;
  55         bool have_result = false;
  56         int ret = call->error;
  57
  58         _enter("%s,%u,%u,%d,%d", server->name, server_index, index, ret, call->abort_code);
  59
  60         spin_lock(&server->probe_lock);
  61
  62         switch (ret) {
  63         case 0:
  64                 server->probe.error = 0;
  65                 goto responded;
  66         case -ECONNABORTED:
  67                 if (!(server->probe.flags & AFS_VLSERVER_PROBE_RESPONDED)) {
  68                         server->probe.abort_code = call->abort_code;
  69                         server->probe.error = ret;
  70                 }
  71                 goto responded;
  72         case -ENOMEM:
  73         case -ENONET:
  74         case -EKEYEXPIRED:
  75         case -EKEYREVOKED:
  76         case -EKEYREJECTED:
  77                 server->probe.flags |= AFS_VLSERVER_PROBE_LOCAL_FAILURE;
  78                 if (server->probe.error == 0)
  79                         server->probe.error = ret;
  80                 trace_afs_io_error(call->debug_id, ret, afs_io_error_vl_probe_fail);
  81                 goto out;
  82         case -ECONNRESET: /* Responded, but call expired. */
  83         case -ERFKILL:
  84         case -EADDRNOTAVAIL:
  85         case -ENETUNREACH:
  86         case -EHOSTUNREACH:
  87         case -EHOSTDOWN:
  88         case -ECONNREFUSED:
  89         case -ETIMEDOUT:
  90         case -ETIME:
  91         default:
  92                 clear_bit(index, &alist->responded);
  93                 set_bit(index, &alist->probe_failed);
  94                 if (!(server->probe.flags & AFS_VLSERVER_PROBE_RESPONDED) &&
  95                     (server->probe.error == 0 ||
  96                      server->probe.error == -ETIMEDOUT ||
  97                      server->probe.error == -ETIME))
  98                         server->probe.error = ret;
  99                 trace_afs_io_error(call->debug_id, ret, afs_io_error_vl_probe_fail);
 100                 goto out;
 101         }
 102
 103 responded:
 104         set_bit(index, &alist->responded);
 105         clear_bit(index, &alist->probe_failed);
 106
 107         if (call->service_id == YFS_VL_SERVICE) {
 108                 server->probe.flags |= AFS_VLSERVER_PROBE_IS_YFS;
 109                 set_bit(AFS_VLSERVER_FL_IS_YFS, &server->flags);
 110                 server->service_id = call->service_id;
 111         } else {
 112                 server->probe.flags |= AFS_VLSERVER_PROBE_NOT_YFS;
 113                 if (!(server->probe.flags & AFS_VLSERVER_PROBE_IS_YFS)) {
 114                         clear_bit(AFS_VLSERVER_FL_IS_YFS, &server->flags);
 115                         server->service_id = call->service_id;
 116                 }
 117         }
 118
 119         rtt_us = rxrpc_kernel_get_srtt(addr->peer);
 120         if (rtt_us < server->probe.rtt) {
 121                 server->probe.rtt = rtt_us;
 122                 server->rtt = rtt_us;
 123                 alist->preferred = index;
 124         }
 125
 126         smp_wmb(); /* Set rtt before responded. */
 127         server->probe.flags |= AFS_VLSERVER_PROBE_RESPONDED;
 128         set_bit(AFS_VLSERVER_FL_PROBED, &server->flags);
 129         set_bit(AFS_VLSERVER_FL_RESPONDING, &server->flags);
 130         have_result = true;
 131 out:
 132         spin_unlock(&server->probe_lock);
 133
 134         trace_afs_vl_probe(server, false, alist, index, call->error, call->abort_code, rtt_us);
 135         _debug("probe [%u][%u] %pISpc rtt=%d ret=%d",
 136                server_index, index, rxrpc_kernel_remote_addr(addr->peer),
 137                rtt_us, ret);
 138
 139         afs_done_one_vl_probe(server, have_result);
 140 }
 141
 142 /*
 143  * Probe all of a vlserver's addresses to find out the best route and to
 144  * query its capabilities.
 145  */
 146 static bool afs_do_probe_vlserver(struct afs_net *net,
 147                                   struct afs_vlserver *server,
 148                                   struct key *key,
 149                                   unsigned int server_index,
 150                                   struct afs_error *_e)
 151 {
 152         struct afs_addr_list *alist;
 153         struct afs_call *call;
 154         unsigned long unprobed;
 155         unsigned int index, i;
 156         bool in_progress = false;
 157         int best_prio;
 158
 159         _enter("%s", server->name);
 160
 161         read_lock(&server->lock);
 162         alist = rcu_dereference_protected(server->addresses,
 163                                           lockdep_is_held(&server->lock));
 164         afs_get_addrlist(alist, afs_alist_trace_get_vlprobe);
 165         read_unlock(&server->lock);
 166
 167         atomic_set(&server->probe_outstanding, alist->nr_addrs);
 168         memset(&server->probe, 0, sizeof(server->probe));
 169         server->probe.rtt = UINT_MAX;
 170
 171         unprobed = (1UL << alist->nr_addrs) - 1;
 172         while (unprobed) {
 173                 best_prio = -1;
 174                 index = 0;
 175                 for (i = 0; i < alist->nr_addrs; i++) {
 176                         if (test_bit(i, &unprobed) &&
 177                             alist->addrs[i].prio > best_prio) {
 178                                 index = i;
 179                                 best_prio = alist->addrs[i].prio;
 180                         }
 181                 }
 182                 __clear_bit(index, &unprobed);
 183
 184                 trace_afs_vl_probe(server, true, alist, index, 0, 0, 0);
 185                 call = afs_vl_get_capabilities(net, alist, index, key, server,
 186                                                server_index);
 187                 if (!IS_ERR(call)) {
 188                         afs_prioritise_error(_e, call->error, call->abort_code);
 189                         afs_put_call(call);
 190                         in_progress = true;
 191                 } else {
 192                         afs_prioritise_error(_e, PTR_ERR(call), 0);
 193                         afs_done_one_vl_probe(server, false);
 194                 }
 195         }
 196
 197         afs_put_addrlist(alist, afs_alist_trace_put_vlprobe);
 198         return in_progress;
 199 }
 200
 201 /*
 202  * Send off probes to all unprobed servers.
 203  */
 204 int afs_send_vl_probes(struct afs_net *net, struct key *key,
 205                        struct afs_vlserver_list *vllist)
 206 {
 207         struct afs_vlserver *server;
 208         struct afs_error e = {};
 209         bool in_progress = false;
 210         int i;
 211
 212         for (i = 0; i < vllist->nr_servers; i++) {
 213                 server = vllist->servers[i].server;
 214                 if (test_bit(AFS_VLSERVER_FL_PROBED, &server->flags))
 215                         continue;
 216
 217                 if (!test_and_set_bit_lock(AFS_VLSERVER_FL_PROBING, &server->flags) &&
 218                     afs_do_probe_vlserver(net, server, key, i, &e))
 219                         in_progress = true;
 220         }
 221
 222         return in_progress ? 0 : e.error;
 223 }
 224
 225 /*
 226  * Wait for the first as-yet untried server to respond.
 227  */
 228 int afs_wait_for_vl_probes(struct afs_vlserver_list *vllist,
 229                            unsigned long untried)
 230 {
 231         struct wait_queue_entry *waits;
 232         struct afs_vlserver *server;
 233         unsigned int rtt = UINT_MAX, rtt_s;
 234         bool have_responders = false;
 235         int pref = -1, i;
 236
 237         _enter("%u,%lx", vllist->nr_servers, untried);
 238
 239         /* Only wait for servers that have a probe outstanding. */
 240         for (i = 0; i < vllist->nr_servers; i++) {
 241                 if (test_bit(i, &untried)) {
 242                         server = vllist->servers[i].server;
 243                         if (!test_bit(AFS_VLSERVER_FL_PROBING, &server->flags))
 244                                 __clear_bit(i, &untried);
 245                         if (server->probe.flags & AFS_VLSERVER_PROBE_RESPONDED)
 246                                 have_responders = true;
 247                 }
 248         }
 249         if (have_responders || !untried)
 250                 return 0;
 251
 252         waits = kmalloc(array_size(vllist->nr_servers, sizeof(*waits)), GFP_KERNEL);
 253         if (!waits)
 254                 return -ENOMEM;
 255
 256         for (i = 0; i < vllist->nr_servers; i++) {
 257                 if (test_bit(i, &untried)) {
 258                         server = vllist->servers[i].server;
 259                         init_waitqueue_entry(&waits[i], current);
 260                         add_wait_queue(&server->probe_wq, &waits[i]);
 261                 }
 262         }
 263
 264         for (;;) {
 265                 bool still_probing = false;
 266
 267                 set_current_state(TASK_INTERRUPTIBLE);
 268                 for (i = 0; i < vllist->nr_servers; i++) {
 269                         if (test_bit(i, &untried)) {
 270                                 server = vllist->servers[i].server;
 271                                 if (server->probe.flags & AFS_VLSERVER_PROBE_RESPONDED)
 272                                         goto stop;
 273                                 if (test_bit(AFS_VLSERVER_FL_PROBING, &server->flags))
 274                                         still_probing = true;
 275                         }
 276                 }
 277
 278                 if (!still_probing || signal_pending(current))
 279                         goto stop;
 280                 schedule();
 281         }
 282
 283 stop:
 284         set_current_state(TASK_RUNNING);
 285
 286         for (i = 0; i < vllist->nr_servers; i++) {
 287                 if (test_bit(i, &untried)) {
 288                         server = vllist->servers[i].server;
 289                         rtt_s = READ_ONCE(server->rtt);
 290                         if (test_bit(AFS_VLSERVER_FL_RESPONDING, &server->flags) &&
 291                             rtt_s < rtt) {
 292                                 pref = i;
 293                                 rtt = rtt_s;
 294                         }
 295
 296                         remove_wait_queue(&server->probe_wq, &waits[i]);
 297                 }
 298         }
 299
 300         kfree(waits);
 301
 302         if (pref == -1 && signal_pending(current))
 303                 return -ERESTARTSYS;
 304
 305         if (pref >= 0)
 306                 vllist->preferred = pref;
 307
 308         _leave(" = 0 [%u]", pref);
 309         return 0;
 310 }