fs/afs/fs_probe.c

   1 /* AFS fileserver probing
   2  *
   3  * Copyright (C) 2018 Red Hat, Inc. All Rights Reserved.
   4  * Written by David Howells (dhowells@redhat.com)
   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/sched.h>
  13 #include <linux/slab.h>
  14 #include "afs_fs.h"
  15 #include "internal.h"
  16 #include "protocol_yfs.h"
  17
  18 static bool afs_fs_probe_done(struct afs_server *server)
  19 {
  20         if (!atomic_dec_and_test(&server->probe_outstanding))
  21                 return false;
  22
  23         wake_up_var(&server->probe_outstanding);
  24         clear_bit_unlock(AFS_SERVER_FL_PROBING, &server->flags);
  25         wake_up_bit(&server->flags, AFS_SERVER_FL_PROBING);
  26         return true;
  27 }
  28
  29 /*
  30  * Process the result of probing a fileserver.  This is called after successful
  31  * or failed delivery of an FS.GetCapabilities operation.
  32  */
  33 void afs_fileserver_probe_result(struct afs_call *call)
  34 {
  35         struct afs_addr_list *alist = call->alist;
  36         struct afs_server *server = call->reply[0];
  37         unsigned int server_index = (long)call->reply[1];
  38         unsigned int index = call->addr_ix;
  39         unsigned int rtt = UINT_MAX;
  40         bool have_result = false;
  41         u64 _rtt;
  42         int ret = call->error;
  43
  44         _enter("%pU,%u", &server->uuid, index);
  45
  46         spin_lock(&server->probe_lock);
  47
  48         switch (ret) {
  49         case 0:
  50                 server->probe.error = 0;
  51                 goto responded;
  52         case -ECONNABORTED:
  53                 if (!server->probe.responded) {
  54                         server->probe.abort_code = call->abort_code;
  55                         server->probe.error = ret;
  56                 }
  57                 goto responded;
  58         case -ENOMEM:
  59         case -ENONET:
  60                 server->probe.local_failure = true;
  61                 afs_io_error(call, afs_io_error_fs_probe_fail);
  62                 goto out;
  63         case -ECONNRESET: /* Responded, but call expired. */
  64         case -ERFKILL:
  65         case -EADDRNOTAVAIL:
  66         case -ENETUNREACH:
  67         case -EHOSTUNREACH:
  68         case -EHOSTDOWN:
  69         case -ECONNREFUSED:
  70         case -ETIMEDOUT:
  71         case -ETIME:
  72         default:
  73                 clear_bit(index, &alist->responded);
  74                 set_bit(index, &alist->failed);
  75                 if (!server->probe.responded &&
  76                     (server->probe.error == 0 ||
  77                      server->probe.error == -ETIMEDOUT ||
  78                      server->probe.error == -ETIME))
  79                         server->probe.error = ret;
  80                 afs_io_error(call, afs_io_error_fs_probe_fail);
  81                 goto out;
  82         }
  83
  84 responded:
  85         set_bit(index, &alist->responded);
  86         clear_bit(index, &alist->failed);
  87
  88         if (call->service_id == YFS_FS_SERVICE) {
  89                 server->probe.is_yfs = true;
  90                 set_bit(AFS_SERVER_FL_IS_YFS, &server->flags);
  91                 alist->addrs[index].srx_service = call->service_id;
  92         } else {
  93                 server->probe.not_yfs = true;
  94                 if (!server->probe.is_yfs) {
  95                         clear_bit(AFS_SERVER_FL_IS_YFS, &server->flags);
  96                         alist->addrs[index].srx_service = call->service_id;
  97                 }
  98         }
  99
 100         /* Get the RTT and scale it to fit into a 32-bit value that represents
 101          * over a minute of time so that we can access it with one instruction
 102          * on a 32-bit system.
 103          */
 104         _rtt = rxrpc_kernel_get_rtt(call->net->socket, call->rxcall);
 105         _rtt /= 64;
 106         rtt = (_rtt > UINT_MAX) ? UINT_MAX : _rtt;
 107         if (rtt < server->probe.rtt) {
 108                 server->probe.rtt = rtt;
 109                 alist->preferred = index;
 110                 have_result = true;
 111         }
 112
 113         smp_wmb(); /* Set rtt before responded. */
 114         server->probe.responded = true;
 115         set_bit(AFS_SERVER_FL_PROBED, &server->flags);
 116 out:
 117         spin_unlock(&server->probe_lock);
 118
 119         _debug("probe [%u][%u] %pISpc rtt=%u ret=%d",
 120                server_index, index, &alist->addrs[index].transport,
 121                (unsigned int)rtt, ret);
 122
 123         have_result |= afs_fs_probe_done(server);
 124         if (have_result) {
 125                 server->probe.have_result = true;
 126                 wake_up_var(&server->probe.have_result);
 127                 wake_up_all(&server->probe_wq);
 128         }
 129 }
 130
 131 /*
 132  * Probe all of a fileserver's addresses to find out the best route and to
 133  * query its capabilities.
 134  */
 135 static int afs_do_probe_fileserver(struct afs_net *net,
 136                                    struct afs_server *server,
 137                                    struct key *key,
 138                                    unsigned int server_index,
 139                                    struct afs_error *_e)
 140 {
 141         struct afs_addr_cursor ac = {
 142                 .index = 0,
 143         };
 144         struct afs_call *call;
 145         bool in_progress = false;
 146
 147         _enter("%pU", &server->uuid);
 148
 149         read_lock(&server->fs_lock);
 150         ac.alist = rcu_dereference_protected(server->addresses,
 151                                              lockdep_is_held(&server->fs_lock));
 152         read_unlock(&server->fs_lock);
 153
 154         atomic_set(&server->probe_outstanding, ac.alist->nr_addrs);
 155         memset(&server->probe, 0, sizeof(server->probe));
 156         server->probe.rtt = UINT_MAX;
 157
 158         for (ac.index = 0; ac.index < ac.alist->nr_addrs; ac.index++) {
 159                 call = afs_fs_get_capabilities(net, server, &ac, key, server_index);
 160                 if (!IS_ERR(call)) {
 161                         afs_put_call(call);
 162                         in_progress = true;
 163                 } else {
 164                         afs_prioritise_error(_e, PTR_ERR(call), ac.abort_code);
 165                 }
 166         }
 167
 168         if (!in_progress)
 169                 afs_fs_probe_done(server);
 170         return in_progress;
 171 }
 172
 173 /*
 174  * Send off probes to all unprobed servers.
 175  */
 176 int afs_probe_fileservers(struct afs_net *net, struct key *key,
 177                           struct afs_server_list *list)
 178 {
 179         struct afs_server *server;
 180         struct afs_error e;
 181         bool in_progress = false;
 182         int i;
 183
 184         e.error = 0;
 185         e.responded = false;
 186         for (i = 0; i < list->nr_servers; i++) {
 187                 server = list->servers[i].server;
 188                 if (test_bit(AFS_SERVER_FL_PROBED, &server->flags))
 189                         continue;
 190
 191                 if (!test_and_set_bit_lock(AFS_SERVER_FL_PROBING, &server->flags) &&
 192                     afs_do_probe_fileserver(net, server, key, i, &e))
 193                         in_progress = true;
 194         }
 195
 196         return in_progress ? 0 : e.error;
 197 }
 198
 199 /*
 200  * Wait for the first as-yet untried fileserver to respond.
 201  */
 202 int afs_wait_for_fs_probes(struct afs_server_list *slist, unsigned long untried)
 203 {
 204         struct wait_queue_entry *waits;
 205         struct afs_server *server;
 206         unsigned int rtt = UINT_MAX;
 207         bool have_responders = false;
 208         int pref = -1, i;
 209
 210         _enter("%u,%lx", slist->nr_servers, untried);
 211
 212         /* Only wait for servers that have a probe outstanding. */
 213         for (i = 0; i < slist->nr_servers; i++) {
 214                 if (test_bit(i, &untried)) {
 215                         server = slist->servers[i].server;
 216                         if (!test_bit(AFS_SERVER_FL_PROBING, &server->flags))
 217                                 __clear_bit(i, &untried);
 218                         if (server->probe.responded)
 219                                 have_responders = true;
 220                 }
 221         }
 222         if (have_responders || !untried)
 223                 return 0;
 224
 225         waits = kmalloc(array_size(slist->nr_servers, sizeof(*waits)), GFP_KERNEL);
 226         if (!waits)
 227                 return -ENOMEM;
 228
 229         for (i = 0; i < slist->nr_servers; i++) {
 230                 if (test_bit(i, &untried)) {
 231                         server = slist->servers[i].server;
 232                         init_waitqueue_entry(&waits[i], current);
 233                         add_wait_queue(&server->probe_wq, &waits[i]);
 234                 }
 235         }
 236
 237         for (;;) {
 238                 bool still_probing = false;
 239
 240                 set_current_state(TASK_INTERRUPTIBLE);
 241                 for (i = 0; i < slist->nr_servers; i++) {
 242                         if (test_bit(i, &untried)) {
 243                                 server = slist->servers[i].server;
 244                                 if (server->probe.responded)
 245                                         goto stop;
 246                                 if (test_bit(AFS_SERVER_FL_PROBING, &server->flags))
 247                                         still_probing = true;
 248                         }
 249                 }
 250
 251                 if (!still_probing || signal_pending(current))
 252                         goto stop;
 253                 schedule();
 254         }
 255
 256 stop:
 257         set_current_state(TASK_RUNNING);
 258
 259         for (i = 0; i < slist->nr_servers; i++) {
 260                 if (test_bit(i, &untried)) {
 261                         server = slist->servers[i].server;
 262                         if (server->probe.responded &&
 263                             server->probe.rtt < rtt) {
 264                                 pref = i;
 265                                 rtt = server->probe.rtt;
 266                         }
 267
 268                         remove_wait_queue(&server->probe_wq, &waits[i]);
 269                 }
 270         }
 271
 272         kfree(waits);
 273
 274         if (pref == -1 && signal_pending(current))
 275                 return -ERESTARTSYS;
 276
 277         if (pref >= 0)
 278                 slist->preferred = pref;
 279         return 0;
 280 }