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 -ENETUNREACH:
  65         case -EHOSTUNREACH:
  66         case -ECONNREFUSED:
  67         case -ETIMEDOUT:
  68         case -ETIME:
  69         default:
  70                 clear_bit(index, &alist->responded);
  71                 set_bit(index, &alist->failed);
  72                 if (!server->probe.responded &&
  73                     (server->probe.error == 0 ||
  74                      server->probe.error == -ETIMEDOUT ||
  75                      server->probe.error == -ETIME))
  76                         server->probe.error = ret;
  77                 afs_io_error(call, afs_io_error_fs_probe_fail);
  78                 goto out;
  79         }
  80
  81 responded:
  82         set_bit(index, &alist->responded);
  83         clear_bit(index, &alist->failed);
  84
  85         if (call->service_id == YFS_FS_SERVICE) {
  86                 server->probe.is_yfs = true;
  87                 set_bit(AFS_SERVER_FL_IS_YFS, &server->flags);
  88                 alist->addrs[index].srx_service = call->service_id;
  89         } else {
  90                 server->probe.not_yfs = true;
  91                 if (!server->probe.is_yfs) {
  92                         clear_bit(AFS_SERVER_FL_IS_YFS, &server->flags);
  93                         alist->addrs[index].srx_service = call->service_id;
  94                 }
  95         }
  96
  97         /* Get the RTT and scale it to fit into a 32-bit value that represents
  98          * over a minute of time so that we can access it with one instruction
  99          * on a 32-bit system.
 100          */
 101         _rtt = rxrpc_kernel_get_rtt(call->net->socket, call->rxcall);
 102         _rtt /= 64;
 103         rtt = (_rtt > UINT_MAX) ? UINT_MAX : _rtt;
 104         if (rtt < server->probe.rtt) {
 105                 server->probe.rtt = rtt;
 106                 alist->preferred = index;
 107                 have_result = true;
 108         }
 109
 110         smp_wmb(); /* Set rtt before responded. */
 111         server->probe.responded = true;
 112         set_bit(AFS_SERVER_FL_PROBED, &server->flags);
 113 out:
 114         spin_unlock(&server->probe_lock);
 115
 116         _debug("probe [%u][%u] %pISpc rtt=%u ret=%d",
 117                server_index, index, &alist->addrs[index].transport,
 118                (unsigned int)rtt, ret);
 119
 120         have_result |= afs_fs_probe_done(server);
 121         if (have_result) {
 122                 server->probe.have_result = true;
 123                 wake_up_var(&server->probe.have_result);
 124                 wake_up_all(&server->probe_wq);
 125         }
 126 }
 127
 128 /*
 129  * Probe all of a fileserver's addresses to find out the best route and to
 130  * query its capabilities.
 131  */
 132 static int afs_do_probe_fileserver(struct afs_net *net,
 133                                    struct afs_server *server,
 134                                    struct key *key,
 135                                    unsigned int server_index)
 136 {
 137         struct afs_addr_cursor ac = {
 138                 .index = 0,
 139         };
 140         int ret;
 141
 142         _enter("%pU", &server->uuid);
 143
 144         read_lock(&server->fs_lock);
 145         ac.alist = rcu_dereference_protected(server->addresses,
 146                                              lockdep_is_held(&server->fs_lock));
 147         read_unlock(&server->fs_lock);
 148
 149         atomic_set(&server->probe_outstanding, ac.alist->nr_addrs);
 150         memset(&server->probe, 0, sizeof(server->probe));
 151         server->probe.rtt = UINT_MAX;
 152
 153         for (ac.index = 0; ac.index < ac.alist->nr_addrs; ac.index++) {
 154                 ret = afs_fs_get_capabilities(net, server, &ac, key, server_index,
 155                                               true);
 156                 if (ret != -EINPROGRESS) {
 157                         afs_fs_probe_done(server);
 158                         return ret;
 159                 }
 160         }
 161
 162         return 0;
 163 }
 164
 165 /*
 166  * Send off probes to all unprobed servers.
 167  */
 168 int afs_probe_fileservers(struct afs_net *net, struct key *key,
 169                           struct afs_server_list *list)
 170 {
 171         struct afs_server *server;
 172         int i, ret;
 173
 174         for (i = 0; i < list->nr_servers; i++) {
 175                 server = list->servers[i].server;
 176                 if (test_bit(AFS_SERVER_FL_PROBED, &server->flags))
 177                         continue;
 178
 179                 if (!test_and_set_bit_lock(AFS_SERVER_FL_PROBING, &server->flags)) {
 180                         ret = afs_do_probe_fileserver(net, server, key, i);
 181                         if (ret)
 182                                 return ret;
 183                 }
 184         }
 185
 186         return 0;
 187 }
 188
 189 /*
 190  * Wait for the first as-yet untried fileserver to respond.
 191  */
 192 int afs_wait_for_fs_probes(struct afs_server_list *slist, unsigned long untried)
 193 {
 194         struct wait_queue_entry *waits;
 195         struct afs_server *server;
 196         unsigned int rtt = UINT_MAX;
 197         bool have_responders = false;
 198         int pref = -1, i;
 199
 200         _enter("%u,%lx", slist->nr_servers, untried);
 201
 202         /* Only wait for servers that have a probe outstanding. */
 203         for (i = 0; i < slist->nr_servers; i++) {
 204                 if (test_bit(i, &untried)) {
 205                         server = slist->servers[i].server;
 206                         if (!test_bit(AFS_SERVER_FL_PROBING, &server->flags))
 207                                 __clear_bit(i, &untried);
 208                         if (server->probe.responded)
 209                                 have_responders = true;
 210                 }
 211         }
 212         if (have_responders || !untried)
 213                 return 0;
 214
 215         waits = kmalloc(array_size(slist->nr_servers, sizeof(*waits)), GFP_KERNEL);
 216         if (!waits)
 217                 return -ENOMEM;
 218
 219         for (i = 0; i < slist->nr_servers; i++) {
 220                 if (test_bit(i, &untried)) {
 221                         server = slist->servers[i].server;
 222                         init_waitqueue_entry(&waits[i], current);
 223                         add_wait_queue(&server->probe_wq, &waits[i]);
 224                 }
 225         }
 226
 227         for (;;) {
 228                 bool still_probing = false;
 229
 230                 set_current_state(TASK_INTERRUPTIBLE);
 231                 for (i = 0; i < slist->nr_servers; i++) {
 232                         if (test_bit(i, &untried)) {
 233                                 server = slist->servers[i].server;
 234                                 if (server->probe.responded)
 235                                         goto stop;
 236                                 if (test_bit(AFS_SERVER_FL_PROBING, &server->flags))
 237                                         still_probing = true;
 238                         }
 239                 }
 240
 241                 if (!still_probing || unlikely(signal_pending(current)))
 242                         goto stop;
 243                 schedule();
 244         }
 245
 246 stop:
 247         set_current_state(TASK_RUNNING);
 248
 249         for (i = 0; i < slist->nr_servers; i++) {
 250                 if (test_bit(i, &untried)) {
 251                         server = slist->servers[i].server;
 252                         if (server->probe.responded &&
 253                             server->probe.rtt < rtt) {
 254                                 pref = i;
 255                                 rtt = server->probe.rtt;
 256                         }
 257
 258                         remove_wait_queue(&server->probe_wq, &waits[i]);
 259                 }
 260         }
 261
 262         kfree(waits);
 263
 264         if (pref == -1 && signal_pending(current))
 265                 return -ERESTARTSYS;
 266
 267         if (pref >= 0)
 268                 slist->preferred = pref;
 269         return 0;
 270 }