fs/afs/fs_probe.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /* AFS fileserver 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 static bool afs_fs_probe_done(struct afs_server *server)
  15 {
  16         if (!atomic_dec_and_test(&server->probe_outstanding))
  17                 return false;
  18
  19         wake_up_var(&server->probe_outstanding);
  20         clear_bit_unlock(AFS_SERVER_FL_PROBING, &server->flags);
  21         wake_up_bit(&server->flags, AFS_SERVER_FL_PROBING);
  22         return true;
  23 }
  24
  25 /*
  26  * Process the result of probing a fileserver.  This is called after successful
  27  * or failed delivery of an FS.GetCapabilities operation.
  28  */
  29 void afs_fileserver_probe_result(struct afs_call *call)
  30 {
  31         struct afs_addr_list *alist = call->alist;
  32         struct afs_server *server = call->server;
  33         unsigned int server_index = call->server_index;
  34         unsigned int index = call->addr_ix;
  35         unsigned int rtt = UINT_MAX;
  36         bool have_result = false;
  37         u64 _rtt;
  38         int ret = call->error;
  39
  40         _enter("%pU,%u", &server->uuid, index);
  41
  42         spin_lock(&server->probe_lock);
  43
  44         switch (ret) {
  45         case 0:
  46                 server->probe.error = 0;
  47                 goto responded;
  48         case -ECONNABORTED:
  49                 if (!server->probe.responded) {
  50                         server->probe.abort_code = call->abort_code;
  51                         server->probe.error = ret;
  52                 }
  53                 goto responded;
  54         case -ENOMEM:
  55         case -ENONET:
  56                 server->probe.local_failure = true;
  57                 afs_io_error(call, afs_io_error_fs_probe_fail);
  58                 goto out;
  59         case -ECONNRESET: /* Responded, but call expired. */
  60         case -ERFKILL:
  61         case -EADDRNOTAVAIL:
  62         case -ENETUNREACH:
  63         case -EHOSTUNREACH:
  64         case -EHOSTDOWN:
  65         case -ECONNREFUSED:
  66         case -ETIMEDOUT:
  67         case -ETIME:
  68         default:
  69                 clear_bit(index, &alist->responded);
  70                 set_bit(index, &alist->failed);
  71                 if (!server->probe.responded &&
  72                     (server->probe.error == 0 ||
  73                      server->probe.error == -ETIMEDOUT ||
  74                      server->probe.error == -ETIME))
  75                         server->probe.error = ret;
  76                 afs_io_error(call, afs_io_error_fs_probe_fail);
  77                 goto out;
  78         }
  79
  80 responded:
  81         set_bit(index, &alist->responded);
  82         clear_bit(index, &alist->failed);
  83
  84         if (call->service_id == YFS_FS_SERVICE) {
  85                 server->probe.is_yfs = true;
  86                 set_bit(AFS_SERVER_FL_IS_YFS, &server->flags);
  87                 alist->addrs[index].srx_service = call->service_id;
  88         } else {
  89                 server->probe.not_yfs = true;
  90                 if (!server->probe.is_yfs) {
  91                         clear_bit(AFS_SERVER_FL_IS_YFS, &server->flags);
  92                         alist->addrs[index].srx_service = call->service_id;
  93                 }
  94         }
  95
  96         /* Get the RTT and scale it to fit into a 32-bit value that represents
  97          * over a minute of time so that we can access it with one instruction
  98          * on a 32-bit system.
  99          */
 100         _rtt = rxrpc_kernel_get_rtt(call->net->socket, call->rxcall);
 101         _rtt /= 64;
 102         rtt = (_rtt > UINT_MAX) ? UINT_MAX : _rtt;
 103         if (rtt < server->probe.rtt) {
 104                 server->probe.rtt = rtt;
 105                 alist->preferred = index;
 106                 have_result = true;
 107         }
 108
 109         smp_wmb(); /* Set rtt before responded. */
 110         server->probe.responded = true;
 111         set_bit(AFS_SERVER_FL_PROBED, &server->flags);
 112 out:
 113         spin_unlock(&server->probe_lock);
 114
 115         _debug("probe [%u][%u] %pISpc rtt=%u ret=%d",
 116                server_index, index, &alist->addrs[index].transport,
 117                (unsigned int)rtt, ret);
 118
 119         have_result |= afs_fs_probe_done(server);
 120         if (have_result)
 121                 wake_up_all(&server->probe_wq);
 122 }
 123
 124 /*
 125  * Probe all of a fileserver's addresses to find out the best route and to
 126  * query its capabilities.
 127  */
 128 static int afs_do_probe_fileserver(struct afs_net *net,
 129                                    struct afs_server *server,
 130                                    struct key *key,
 131                                    unsigned int server_index,
 132                                    struct afs_error *_e)
 133 {
 134         struct afs_addr_cursor ac = {
 135                 .index = 0,
 136         };
 137         struct afs_call *call;
 138         bool in_progress = false;
 139
 140         _enter("%pU", &server->uuid);
 141
 142         read_lock(&server->fs_lock);
 143         ac.alist = rcu_dereference_protected(server->addresses,
 144                                              lockdep_is_held(&server->fs_lock));
 145         afs_get_addrlist(ac.alist);
 146         read_unlock(&server->fs_lock);
 147
 148         atomic_set(&server->probe_outstanding, ac.alist->nr_addrs);
 149         memset(&server->probe, 0, sizeof(server->probe));
 150         server->probe.rtt = UINT_MAX;
 151
 152         for (ac.index = 0; ac.index < ac.alist->nr_addrs; ac.index++) {
 153                 call = afs_fs_get_capabilities(net, server, &ac, key, server_index);
 154                 if (!IS_ERR(call)) {
 155                         afs_put_call(call);
 156                         in_progress = true;
 157                 } else {
 158                         afs_prioritise_error(_e, PTR_ERR(call), ac.abort_code);
 159                 }
 160         }
 161
 162         if (!in_progress)
 163                 afs_fs_probe_done(server);
 164         afs_put_addrlist(ac.alist);
 165         return in_progress;
 166 }
 167
 168 /*
 169  * Send off probes to all unprobed servers.
 170  */
 171 int afs_probe_fileservers(struct afs_net *net, struct key *key,
 172                           struct afs_server_list *list)
 173 {
 174         struct afs_server *server;
 175         struct afs_error e;
 176         bool in_progress = false;
 177         int i;
 178
 179         e.error = 0;
 180         e.responded = false;
 181         for (i = 0; i < list->nr_servers; i++) {
 182                 server = list->servers[i].server;
 183                 if (test_bit(AFS_SERVER_FL_PROBED, &server->flags))
 184                         continue;
 185
 186                 if (!test_and_set_bit_lock(AFS_SERVER_FL_PROBING, &server->flags) &&
 187                     afs_do_probe_fileserver(net, server, key, i, &e))
 188                         in_progress = true;
 189         }
 190
 191         return in_progress ? 0 : e.error;
 192 }
 193
 194 /*
 195  * Wait for the first as-yet untried fileserver to respond.
 196  */
 197 int afs_wait_for_fs_probes(struct afs_server_list *slist, unsigned long untried)
 198 {
 199         struct wait_queue_entry *waits;
 200         struct afs_server *server;
 201         unsigned int rtt = UINT_MAX;
 202         bool have_responders = false;
 203         int pref = -1, i;
 204
 205         _enter("%u,%lx", slist->nr_servers, untried);
 206
 207         /* Only wait for servers that have a probe outstanding. */
 208         for (i = 0; i < slist->nr_servers; i++) {
 209                 if (test_bit(i, &untried)) {
 210                         server = slist->servers[i].server;
 211                         if (!test_bit(AFS_SERVER_FL_PROBING, &server->flags))
 212                                 __clear_bit(i, &untried);
 213                         if (server->probe.responded)
 214                                 have_responders = true;
 215                 }
 216         }
 217         if (have_responders || !untried)
 218                 return 0;
 219
 220         waits = kmalloc(array_size(slist->nr_servers, sizeof(*waits)), GFP_KERNEL);
 221         if (!waits)
 222                 return -ENOMEM;
 223
 224         for (i = 0; i < slist->nr_servers; i++) {
 225                 if (test_bit(i, &untried)) {
 226                         server = slist->servers[i].server;
 227                         init_waitqueue_entry(&waits[i], current);
 228                         add_wait_queue(&server->probe_wq, &waits[i]);
 229                 }
 230         }
 231
 232         for (;;) {
 233                 bool still_probing = false;
 234
 235                 set_current_state(TASK_INTERRUPTIBLE);
 236                 for (i = 0; i < slist->nr_servers; i++) {
 237                         if (test_bit(i, &untried)) {
 238                                 server = slist->servers[i].server;
 239                                 if (server->probe.responded)
 240                                         goto stop;
 241                                 if (test_bit(AFS_SERVER_FL_PROBING, &server->flags))
 242                                         still_probing = true;
 243                         }
 244                 }
 245
 246                 if (!still_probing || signal_pending(current))
 247                         goto stop;
 248                 schedule();
 249         }
 250
 251 stop:
 252         set_current_state(TASK_RUNNING);
 253
 254         for (i = 0; i < slist->nr_servers; i++) {
 255                 if (test_bit(i, &untried)) {
 256                         server = slist->servers[i].server;
 257                         if (server->probe.responded &&
 258                             server->probe.rtt < rtt) {
 259                                 pref = i;
 260                                 rtt = server->probe.rtt;
 261                         }
 262
 263                         remove_wait_queue(&server->probe_wq, &waits[i]);
 264                 }
 265         }
 266
 267         kfree(waits);
 268
 269         if (pref == -1 && signal_pending(current))
 270                 return -ERESTARTSYS;
 271
 272         if (pref >= 0)
 273                 slist->preferred = pref;
 274         return 0;
 275 }