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->alist;
  50         struct afs_vlserver *server = call->vlserver;
  51         unsigned int server_index = call->server_index;
  52         unsigned int rtt_us = 0;
  53         unsigned int index = call->addr_ix;
  54         bool have_result = false;
  55         int ret = call->error;
  56
  57         _enter("%s,%u,%u,%d,%d", server->name, server_index, index, ret, call->abort_code);
  58
  59         spin_lock(&server->probe_lock);
  60
  61         switch (ret) {
  62         case 0:
  63                 server->probe.error = 0;
  64                 goto responded;
  65         case -ECONNABORTED:
  66                 if (!(server->probe.flags & AFS_VLSERVER_PROBE_RESPONDED)) {
  67                         server->probe.abort_code = call->abort_code;
  68                         server->probe.error = ret;
  69                 }
  70                 goto responded;
  71         case -ENOMEM:
  72         case -ENONET:
  73         case -EKEYEXPIRED:
  74         case -EKEYREVOKED:
  75         case -EKEYREJECTED:
  76                 server->probe.flags |= AFS_VLSERVER_PROBE_LOCAL_FAILURE;
  77                 if (server->probe.error == 0)
  78                         server->probe.error = ret;
  79                 trace_afs_io_error(call->debug_id, ret, afs_io_error_vl_probe_fail);
  80                 goto out;
  81         case -ECONNRESET: /* Responded, but call expired. */
  82         case -ERFKILL:
  83         case -EADDRNOTAVAIL:
  84         case -ENETUNREACH:
  85         case -EHOSTUNREACH:
  86         case -EHOSTDOWN:
  87         case -ECONNREFUSED:
  88         case -ETIMEDOUT:
  89         case -ETIME:
  90         default:
  91                 clear_bit(index, &alist->responded);
  92                 set_bit(index, &alist->failed);
  93                 if (!(server->probe.flags & AFS_VLSERVER_PROBE_RESPONDED) &&
  94                     (server->probe.error == 0 ||
  95                      server->probe.error == -ETIMEDOUT ||
  96                      server->probe.error == -ETIME))
  97                         server->probe.error = ret;
  98                 trace_afs_io_error(call->debug_id, ret, afs_io_error_vl_probe_fail);
  99                 goto out;
 100         }
 101
 102 responded:
 103         set_bit(index, &alist->responded);
 104         clear_bit(index, &alist->failed);
 105
 106         if (call->service_id == YFS_VL_SERVICE) {
 107                 server->probe.flags |= AFS_VLSERVER_PROBE_IS_YFS;
 108                 set_bit(AFS_VLSERVER_FL_IS_YFS, &server->flags);
 109                 alist->addrs[index].srx_service = call->service_id;
 110         } else {
 111                 server->probe.flags |= AFS_VLSERVER_PROBE_NOT_YFS;
 112                 if (!(server->probe.flags & AFS_VLSERVER_PROBE_IS_YFS)) {
 113                         clear_bit(AFS_VLSERVER_FL_IS_YFS, &server->flags);
 114                         alist->addrs[index].srx_service = call->service_id;
 115                 }
 116         }
 117
 118         if (rxrpc_kernel_get_srtt(call->net->socket, call->rxcall, &rtt_us) &&
 119             rtt_us < server->probe.rtt) {
 120                 server->probe.rtt = rtt_us;
 121                 server->rtt = rtt_us;
 122                 alist->preferred = index;
 123         }
 124
 125         smp_wmb(); /* Set rtt before responded. */
 126         server->probe.flags |= AFS_VLSERVER_PROBE_RESPONDED;
 127         set_bit(AFS_VLSERVER_FL_PROBED, &server->flags);
 128         set_bit(AFS_VLSERVER_FL_RESPONDING, &server->flags);
 129         have_result = true;
 130 out:
 131         spin_unlock(&server->probe_lock);
 132
 133         _debug("probe [%u][%u] %pISpc rtt=%u ret=%d",
 134                server_index, index, &alist->addrs[index].transport, rtt_us, ret);
 135
 136         afs_done_one_vl_probe(server, have_result);
 137 }
 138
 139 /*
 140  * Probe all of a vlserver's addresses to find out the best route and to
 141  * query its capabilities.
 142  */
 143 static bool afs_do_probe_vlserver(struct afs_net *net,
 144                                   struct afs_vlserver *server,
 145                                   struct key *key,
 146                                   unsigned int server_index,
 147                                   struct afs_error *_e)
 148 {
 149         struct afs_addr_cursor ac = {
 150                 .index = 0,
 151         };
 152         struct afs_call *call;
 153         bool in_progress = false;
 154
 155         _enter("%s", server->name);
 156
 157         read_lock(&server->lock);
 158         ac.alist = rcu_dereference_protected(server->addresses,
 159                                              lockdep_is_held(&server->lock));
 160         read_unlock(&server->lock);
 161
 162         atomic_set(&server->probe_outstanding, ac.alist->nr_addrs);
 163         memset(&server->probe, 0, sizeof(server->probe));
 164         server->probe.rtt = UINT_MAX;
 165
 166         for (ac.index = 0; ac.index < ac.alist->nr_addrs; ac.index++) {
 167                 call = afs_vl_get_capabilities(net, &ac, key, server,
 168                                                server_index);
 169                 if (!IS_ERR(call)) {
 170                         afs_put_call(call);
 171                         in_progress = true;
 172                 } else {
 173                         afs_prioritise_error(_e, PTR_ERR(call), ac.abort_code);
 174                         afs_done_one_vl_probe(server, false);
 175                 }
 176         }
 177
 178         return in_progress;
 179 }
 180
 181 /*
 182  * Send off probes to all unprobed servers.
 183  */
 184 int afs_send_vl_probes(struct afs_net *net, struct key *key,
 185                        struct afs_vlserver_list *vllist)
 186 {
 187         struct afs_vlserver *server;
 188         struct afs_error e;
 189         bool in_progress = false;
 190         int i;
 191
 192         e.error = 0;
 193         e.responded = false;
 194         for (i = 0; i < vllist->nr_servers; i++) {
 195                 server = vllist->servers[i].server;
 196                 if (test_bit(AFS_VLSERVER_FL_PROBED, &server->flags))
 197                         continue;
 198
 199                 if (!test_and_set_bit_lock(AFS_VLSERVER_FL_PROBING, &server->flags) &&
 200                     afs_do_probe_vlserver(net, server, key, i, &e))
 201                         in_progress = true;
 202         }
 203
 204         return in_progress ? 0 : e.error;
 205 }
 206
 207 /*
 208  * Wait for the first as-yet untried server to respond.
 209  */
 210 int afs_wait_for_vl_probes(struct afs_vlserver_list *vllist,
 211                            unsigned long untried)
 212 {
 213         struct wait_queue_entry *waits;
 214         struct afs_vlserver *server;
 215         unsigned int rtt = UINT_MAX, rtt_s;
 216         bool have_responders = false;
 217         int pref = -1, i;
 218
 219         _enter("%u,%lx", vllist->nr_servers, untried);
 220
 221         /* Only wait for servers that have a probe outstanding. */
 222         for (i = 0; i < vllist->nr_servers; i++) {
 223                 if (test_bit(i, &untried)) {
 224                         server = vllist->servers[i].server;
 225                         if (!test_bit(AFS_VLSERVER_FL_PROBING, &server->flags))
 226                                 __clear_bit(i, &untried);
 227                         if (server->probe.flags & AFS_VLSERVER_PROBE_RESPONDED)
 228                                 have_responders = true;
 229                 }
 230         }
 231         if (have_responders || !untried)
 232                 return 0;
 233
 234         waits = kmalloc(array_size(vllist->nr_servers, sizeof(*waits)), GFP_KERNEL);
 235         if (!waits)
 236                 return -ENOMEM;
 237
 238         for (i = 0; i < vllist->nr_servers; i++) {
 239                 if (test_bit(i, &untried)) {
 240                         server = vllist->servers[i].server;
 241                         init_waitqueue_entry(&waits[i], current);
 242                         add_wait_queue(&server->probe_wq, &waits[i]);
 243                 }
 244         }
 245
 246         for (;;) {
 247                 bool still_probing = false;
 248
 249                 set_current_state(TASK_INTERRUPTIBLE);
 250                 for (i = 0; i < vllist->nr_servers; i++) {
 251                         if (test_bit(i, &untried)) {
 252                                 server = vllist->servers[i].server;
 253                                 if (server->probe.flags & AFS_VLSERVER_PROBE_RESPONDED)
 254                                         goto stop;
 255                                 if (test_bit(AFS_VLSERVER_FL_PROBING, &server->flags))
 256                                         still_probing = true;
 257                         }
 258                 }
 259
 260                 if (!still_probing || signal_pending(current))
 261                         goto stop;
 262                 schedule();
 263         }
 264
 265 stop:
 266         set_current_state(TASK_RUNNING);
 267
 268         for (i = 0; i < vllist->nr_servers; i++) {
 269                 if (test_bit(i, &untried)) {
 270                         server = vllist->servers[i].server;
 271                         rtt_s = READ_ONCE(server->rtt);
 272                         if (test_bit(AFS_VLSERVER_FL_RESPONDING, &server->flags) &&
 273                             rtt_s < rtt) {
 274                                 pref = i;
 275                                 rtt = rtt_s;
 276                         }
 277
 278                         remove_wait_queue(&server->probe_wq, &waits[i]);
 279                 }
 280         }
 281
 282         kfree(waits);
 283
 284         if (pref == -1 && signal_pending(current))
 285                 return -ERESTARTSYS;
 286
 287         if (pref >= 0)
 288                 vllist->preferred = pref;
 289
 290         _leave(" = 0 [%u]", pref);
 291         return 0;
 292 }