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                 server->probe.have_result = true;
 122                 wake_up_var(&server->probe.have_result);
 123                 wake_up_all(&server->probe_wq);
 124         }
 125 }
 126
 127 /*
 128  * Probe all of a fileserver's addresses to find out the best route and to
 129  * query its capabilities.
 130  */
 131 static int afs_do_probe_fileserver(struct afs_net *net,
 132                                    struct afs_server *server,
 133                                    struct key *key,
 134                                    unsigned int server_index,
 135                                    struct afs_error *_e)
 136 {
 137         struct afs_addr_cursor ac = {
 138                 .index = 0,
 139         };
 140         struct afs_call *call;
 141         bool in_progress = false;
 142
 143         _enter("%pU", &server->uuid);
 144
 145         read_lock(&server->fs_lock);
 146         ac.alist = rcu_dereference_protected(server->addresses,
 147                                              lockdep_is_held(&server->fs_lock));
 148         read_unlock(&server->fs_lock);
 149
 150         atomic_set(&server->probe_outstanding, ac.alist->nr_addrs);
 151         memset(&server->probe, 0, sizeof(server->probe));
 152         server->probe.rtt = UINT_MAX;
 153
 154         for (ac.index = 0; ac.index < ac.alist->nr_addrs; ac.index++) {
 155                 call = afs_fs_get_capabilities(net, server, &ac, key, server_index);
 156                 if (!IS_ERR(call)) {
 157                         afs_put_call(call);
 158                         in_progress = true;
 159                 } else {
 160                         afs_prioritise_error(_e, PTR_ERR(call), ac.abort_code);
 161                 }
 162         }
 163
 164         if (!in_progress)
 165                 afs_fs_probe_done(server);
 166         return in_progress;
 167 }
 168
 169 /*
 170  * Send off probes to all unprobed servers.
 171  */
 172 int afs_probe_fileservers(struct afs_net *net, struct key *key,
 173                           struct afs_server_list *list)
 174 {
 175         struct afs_server *server;
 176         struct afs_error e;
 177         bool in_progress = false;
 178         int i;
 179
 180         e.error = 0;
 181         e.responded = false;
 182         for (i = 0; i < list->nr_servers; i++) {
 183                 server = list->servers[i].server;
 184                 if (test_bit(AFS_SERVER_FL_PROBED, &server->flags))
 185                         continue;
 186
 187                 if (!test_and_set_bit_lock(AFS_SERVER_FL_PROBING, &server->flags) &&
 188                     afs_do_probe_fileserver(net, server, key, i, &e))
 189                         in_progress = true;
 190         }
 191
 192         return in_progress ? 0 : e.error;
 193 }
 194
 195 /*
 196  * Wait for the first as-yet untried fileserver to respond.
 197  */
 198 int afs_wait_for_fs_probes(struct afs_server_list *slist, unsigned long untried)
 199 {
 200         struct wait_queue_entry *waits;
 201         struct afs_server *server;
 202         unsigned int rtt = UINT_MAX;
 203         bool have_responders = false;
 204         int pref = -1, i;
 205
 206         _enter("%u,%lx", slist->nr_servers, untried);
 207
 208         /* Only wait for servers that have a probe outstanding. */
 209         for (i = 0; i < slist->nr_servers; i++) {
 210                 if (test_bit(i, &untried)) {
 211                         server = slist->servers[i].server;
 212                         if (!test_bit(AFS_SERVER_FL_PROBING, &server->flags))
 213                                 __clear_bit(i, &untried);
 214                         if (server->probe.responded)
 215                                 have_responders = true;
 216                 }
 217         }
 218         if (have_responders || !untried)
 219                 return 0;
 220
 221         waits = kmalloc(array_size(slist->nr_servers, sizeof(*waits)), GFP_KERNEL);
 222         if (!waits)
 223                 return -ENOMEM;
 224
 225         for (i = 0; i < slist->nr_servers; i++) {
 226                 if (test_bit(i, &untried)) {
 227                         server = slist->servers[i].server;
 228                         init_waitqueue_entry(&waits[i], current);
 229                         add_wait_queue(&server->probe_wq, &waits[i]);
 230                 }
 231         }
 232
 233         for (;;) {
 234                 bool still_probing = false;
 235
 236                 set_current_state(TASK_INTERRUPTIBLE);
 237                 for (i = 0; i < slist->nr_servers; i++) {
 238                         if (test_bit(i, &untried)) {
 239                                 server = slist->servers[i].server;
 240                                 if (server->probe.responded)
 241                                         goto stop;
 242                                 if (test_bit(AFS_SERVER_FL_PROBING, &server->flags))
 243                                         still_probing = true;
 244                         }
 245                 }
 246
 247                 if (!still_probing || signal_pending(current))
 248                         goto stop;
 249                 schedule();
 250         }
 251
 252 stop:
 253         set_current_state(TASK_RUNNING);
 254
 255         for (i = 0; i < slist->nr_servers; i++) {
 256                 if (test_bit(i, &untried)) {
 257                         server = slist->servers[i].server;
 258                         if (server->probe.responded &&
 259                             server->probe.rtt < rtt) {
 260                                 pref = i;
 261                                 rtt = server->probe.rtt;
 262                         }
 263
 264                         remove_wait_queue(&server->probe_wq, &waits[i]);
 265                 }
 266         }
 267
 268         kfree(waits);
 269
 270         if (pref == -1 && signal_pending(current))
 271                 return -ERESTARTSYS;
 272
 273         if (pref >= 0)
 274                 slist->preferred = pref;
 275         return 0;
 276 }