LXR linux/fs/afs/fs

   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
  14static 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 */
  29void 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
  80responded:
  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);
 112out:
 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 */
 131static 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 */
 172int 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 */
 198int 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
 252stop:
 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}
 277