fs/afs/vl_probe.c

0001 // SPDX-License-Identifier: GPL-2.0-or-later
0002 /* AFS vlserver probing
0003  *
0004  * Copyright (C) 2018 Red Hat, Inc. All Rights Reserved.
0005  * Written by David Howells (dhowells@redhat.com)
0006  */
0007
0008 #include <linux/sched.h>
0009 #include <linux/slab.h>
0010 #include "afs_fs.h"
0011 #include "internal.h"
0012 #include "protocol_yfs.h"
0013
0014
0015 /*
0016  * Handle the completion of a set of probes.
0017  */
0018 static void afs_finished_vl_probe(struct afs_vlserver *server)
0019 {
0020     if (!(server->probe.flags & AFS_VLSERVER_PROBE_RESPONDED)) {
0021         server->rtt = UINT_MAX;
0022         clear_bit(AFS_VLSERVER_FL_RESPONDING, &server->flags);
0023     }
0024
0025     clear_bit_unlock(AFS_VLSERVER_FL_PROBING, &server->flags);
0026     wake_up_bit(&server->flags, AFS_VLSERVER_FL_PROBING);
0027 }
0028
0029 /*
0030  * Handle the completion of a probe RPC call.
0031  */
0032 static void afs_done_one_vl_probe(struct afs_vlserver *server, bool wake_up)
0033 {
0034     if (atomic_dec_and_test(&server->probe_outstanding)) {
0035         afs_finished_vl_probe(server);
0036         wake_up = true;
0037     }
0038
0039     if (wake_up)
0040         wake_up_all(&server->probe_wq);
0041 }
0042
0043 /*
0044  * Process the result of probing a vlserver.  This is called after successful
0045  * or failed delivery of an VL.GetCapabilities operation.
0046  */
0047 void afs_vlserver_probe_result(struct afs_call *call)
0048 {
0049     struct afs_addr_list *alist = call->alist;
0050     struct afs_vlserver *server = call->vlserver;
0051     unsigned int server_index = call->server_index;
0052     unsigned int rtt_us = 0;
0053     unsigned int index = call->addr_ix;
0054     bool have_result = false;
0055     int ret = call->error;
0056
0057     _enter("%s,%u,%u,%d,%d", server->name, server_index, index, ret, call->abort_code);
0058
0059     spin_lock(&server->probe_lock);
0060
0061     switch (ret) {
0062     case 0:
0063         server->probe.error = 0;
0064         goto responded;
0065     case -ECONNABORTED:
0066         if (!(server->probe.flags & AFS_VLSERVER_PROBE_RESPONDED)) {
0067             server->probe.abort_code = call->abort_code;
0068             server->probe.error = ret;
0069         }
0070         goto responded;
0071     case -ENOMEM:
0072     case -ENONET:
0073     case -EKEYEXPIRED:
0074     case -EKEYREVOKED:
0075     case -EKEYREJECTED:
0076         server->probe.flags |= AFS_VLSERVER_PROBE_LOCAL_FAILURE;
0077         if (server->probe.error == 0)
0078             server->probe.error = ret;
0079         trace_afs_io_error(call->debug_id, ret, afs_io_error_vl_probe_fail);
0080         goto out;
0081     case -ECONNRESET: /* Responded, but call expired. */
0082     case -ERFKILL:
0083     case -EADDRNOTAVAIL:
0084     case -ENETUNREACH:
0085     case -EHOSTUNREACH:
0086     case -EHOSTDOWN:
0087     case -ECONNREFUSED:
0088     case -ETIMEDOUT:
0089     case -ETIME:
0090     default:
0091         clear_bit(index, &alist->responded);
0092         set_bit(index, &alist->failed);
0093         if (!(server->probe.flags & AFS_VLSERVER_PROBE_RESPONDED) &&
0094             (server->probe.error == 0 ||
0095              server->probe.error == -ETIMEDOUT ||
0096              server->probe.error == -ETIME))
0097             server->probe.error = ret;
0098         trace_afs_io_error(call->debug_id, ret, afs_io_error_vl_probe_fail);
0099         goto out;
0100     }
0101
0102 responded:
0103     set_bit(index, &alist->responded);
0104     clear_bit(index, &alist->failed);
0105
0106     if (call->service_id == YFS_VL_SERVICE) {
0107         server->probe.flags |= AFS_VLSERVER_PROBE_IS_YFS;
0108         set_bit(AFS_VLSERVER_FL_IS_YFS, &server->flags);
0109         alist->addrs[index].srx_service = call->service_id;
0110     } else {
0111         server->probe.flags |= AFS_VLSERVER_PROBE_NOT_YFS;
0112         if (!(server->probe.flags & AFS_VLSERVER_PROBE_IS_YFS)) {
0113             clear_bit(AFS_VLSERVER_FL_IS_YFS, &server->flags);
0114             alist->addrs[index].srx_service = call->service_id;
0115         }
0116     }
0117
0118     if (rxrpc_kernel_get_srtt(call->net->socket, call->rxcall, &rtt_us) &&
0119         rtt_us < server->probe.rtt) {
0120         server->probe.rtt = rtt_us;
0121         server->rtt = rtt_us;
0122         alist->preferred = index;
0123     }
0124
0125     smp_wmb(); /* Set rtt before responded. */
0126     server->probe.flags |= AFS_VLSERVER_PROBE_RESPONDED;
0127     set_bit(AFS_VLSERVER_FL_PROBED, &server->flags);
0128     set_bit(AFS_VLSERVER_FL_RESPONDING, &server->flags);
0129     have_result = true;
0130 out:
0131     spin_unlock(&server->probe_lock);
0132
0133     _debug("probe [%u][%u] %pISpc rtt=%u ret=%d",
0134            server_index, index, &alist->addrs[index].transport, rtt_us, ret);
0135
0136     afs_done_one_vl_probe(server, have_result);
0137 }
0138
0139 /*
0140  * Probe all of a vlserver's addresses to find out the best route and to
0141  * query its capabilities.
0142  */
0143 static bool afs_do_probe_vlserver(struct afs_net *net,
0144                   struct afs_vlserver *server,
0145                   struct key *key,
0146                   unsigned int server_index,
0147                   struct afs_error *_e)
0148 {
0149     struct afs_addr_cursor ac = {
0150         .index = 0,
0151     };
0152     struct afs_call *call;
0153     bool in_progress = false;
0154
0155     _enter("%s", server->name);
0156
0157     read_lock(&server->lock);
0158     ac.alist = rcu_dereference_protected(server->addresses,
0159                          lockdep_is_held(&server->lock));
0160     read_unlock(&server->lock);
0161
0162     atomic_set(&server->probe_outstanding, ac.alist->nr_addrs);
0163     memset(&server->probe, 0, sizeof(server->probe));
0164     server->probe.rtt = UINT_MAX;
0165
0166     for (ac.index = 0; ac.index < ac.alist->nr_addrs; ac.index++) {
0167         call = afs_vl_get_capabilities(net, &ac, key, server,
0168                            server_index);
0169         if (!IS_ERR(call)) {
0170             afs_put_call(call);
0171             in_progress = true;
0172         } else {
0173             afs_prioritise_error(_e, PTR_ERR(call), ac.abort_code);
0174             afs_done_one_vl_probe(server, false);
0175         }
0176     }
0177
0178     return in_progress;
0179 }
0180
0181 /*
0182  * Send off probes to all unprobed servers.
0183  */
0184 int afs_send_vl_probes(struct afs_net *net, struct key *key,
0185                struct afs_vlserver_list *vllist)
0186 {
0187     struct afs_vlserver *server;
0188     struct afs_error e;
0189     bool in_progress = false;
0190     int i;
0191
0192     e.error = 0;
0193     e.responded = false;
0194     for (i = 0; i < vllist->nr_servers; i++) {
0195         server = vllist->servers[i].server;
0196         if (test_bit(AFS_VLSERVER_FL_PROBED, &server->flags))
0197             continue;
0198
0199         if (!test_and_set_bit_lock(AFS_VLSERVER_FL_PROBING, &server->flags) &&
0200             afs_do_probe_vlserver(net, server, key, i, &e))
0201             in_progress = true;
0202     }
0203
0204     return in_progress ? 0 : e.error;
0205 }
0206
0207 /*
0208  * Wait for the first as-yet untried server to respond.
0209  */
0210 int afs_wait_for_vl_probes(struct afs_vlserver_list *vllist,
0211                unsigned long untried)
0212 {
0213     struct wait_queue_entry *waits;
0214     struct afs_vlserver *server;
0215     unsigned int rtt = UINT_MAX, rtt_s;
0216     bool have_responders = false;
0217     int pref = -1, i;
0218
0219     _enter("%u,%lx", vllist->nr_servers, untried);
0220
0221     /* Only wait for servers that have a probe outstanding. */
0222     for (i = 0; i < vllist->nr_servers; i++) {
0223         if (test_bit(i, &untried)) {
0224             server = vllist->servers[i].server;
0225             if (!test_bit(AFS_VLSERVER_FL_PROBING, &server->flags))
0226                 __clear_bit(i, &untried);
0227             if (server->probe.flags & AFS_VLSERVER_PROBE_RESPONDED)
0228                 have_responders = true;
0229         }
0230     }
0231     if (have_responders || !untried)
0232         return 0;
0233
0234     waits = kmalloc(array_size(vllist->nr_servers, sizeof(*waits)), GFP_KERNEL);
0235     if (!waits)
0236         return -ENOMEM;
0237
0238     for (i = 0; i < vllist->nr_servers; i++) {
0239         if (test_bit(i, &untried)) {
0240             server = vllist->servers[i].server;
0241             init_waitqueue_entry(&waits[i], current);
0242             add_wait_queue(&server->probe_wq, &waits[i]);
0243         }
0244     }
0245
0246     for (;;) {
0247         bool still_probing = false;
0248
0249         set_current_state(TASK_INTERRUPTIBLE);
0250         for (i = 0; i < vllist->nr_servers; i++) {
0251             if (test_bit(i, &untried)) {
0252                 server = vllist->servers[i].server;
0253                 if (server->probe.flags & AFS_VLSERVER_PROBE_RESPONDED)
0254                     goto stop;
0255                 if (test_bit(AFS_VLSERVER_FL_PROBING, &server->flags))
0256                     still_probing = true;
0257             }
0258         }
0259
0260         if (!still_probing || signal_pending(current))
0261             goto stop;
0262         schedule();
0263     }
0264
0265 stop:
0266     set_current_state(TASK_RUNNING);
0267
0268     for (i = 0; i < vllist->nr_servers; i++) {
0269         if (test_bit(i, &untried)) {
0270             server = vllist->servers[i].server;
0271             rtt_s = READ_ONCE(server->rtt);
0272             if (test_bit(AFS_VLSERVER_FL_RESPONDING, &server->flags) &&
0273                 rtt_s < rtt) {
0274                 pref = i;
0275                 rtt = rtt_s;
0276             }
0277
0278             remove_wait_queue(&server->probe_wq, &waits[i]);
0279         }
0280     }
0281
0282     kfree(waits);
0283
0284     if (pref == -1 && signal_pending(current))
0285         return -ERESTARTSYS;
0286
0287     if (pref >= 0)
0288         vllist->preferred = pref;
0289
0290     _leave(" = 0 [%u]", pref);
0291     return 0;
0292 }