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