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