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1// SPDX-License-Identifier: GPL-2.0-or-later2/* Handle vlserver selection and rotation.3 *4 * Copyright (C) 2018 Red Hat, Inc. All Rights Reserved.5 * Written by David Howells (dhowells@redhat.com)6 */7 8#include <linux/kernel.h>9#include <linux/sched.h>10#include <linux/sched/signal.h>11#include "internal.h"12#include "afs_vl.h"13 14/*15 * Begin an operation on a volume location server.16 */17bool afs_begin_vlserver_operation(struct afs_vl_cursor *vc, struct afs_cell *cell,18 struct key *key)19{20 static atomic_t debug_ids;21 22 memset(vc, 0, sizeof(*vc));23 vc->cell = cell;24 vc->key = key;25 vc->cumul_error.error = -EDESTADDRREQ;26 vc->nr_iterations = -1;27 28 if (signal_pending(current)) {29 vc->cumul_error.error = -EINTR;30 vc->flags |= AFS_VL_CURSOR_STOP;31 return false;32 }33 34 vc->debug_id = atomic_inc_return(&debug_ids);35 return true;36}37 38/*39 * Begin iteration through a server list, starting with the last used server if40 * possible, or the last recorded good server if not.41 */42static bool afs_start_vl_iteration(struct afs_vl_cursor *vc)43{44 struct afs_cell *cell = vc->cell;45 unsigned int dns_lookup_count;46 47 if (cell->dns_source == DNS_RECORD_UNAVAILABLE ||48 cell->dns_expiry <= ktime_get_real_seconds()) {49 dns_lookup_count = smp_load_acquire(&cell->dns_lookup_count);50 set_bit(AFS_CELL_FL_DO_LOOKUP, &cell->flags);51 afs_queue_cell(cell, afs_cell_trace_get_queue_dns);52 53 if (cell->dns_source == DNS_RECORD_UNAVAILABLE) {54 if (wait_var_event_interruptible(55 &cell->dns_lookup_count,56 smp_load_acquire(&cell->dns_lookup_count)57 != dns_lookup_count) < 0) {58 vc->cumul_error.error = -ERESTARTSYS;59 return false;60 }61 }62 63 /* Status load is ordered after lookup counter load */64 if (cell->dns_status == DNS_LOOKUP_GOT_NOT_FOUND) {65 pr_warn("No record of cell %s\n", cell->name);66 vc->cumul_error.error = -ENOENT;67 return false;68 }69 70 if (cell->dns_source == DNS_RECORD_UNAVAILABLE) {71 vc->cumul_error.error = -EDESTADDRREQ;72 return false;73 }74 }75 76 read_lock(&cell->vl_servers_lock);77 vc->server_list = afs_get_vlserverlist(78 rcu_dereference_protected(cell->vl_servers,79 lockdep_is_held(&cell->vl_servers_lock)));80 read_unlock(&cell->vl_servers_lock);81 if (!vc->server_list->nr_servers)82 return false;83 84 vc->untried_servers = (1UL << vc->server_list->nr_servers) - 1;85 vc->server_index = -1;86 return true;87}88 89/*90 * Select the vlserver to use. May be called multiple times to rotate91 * through the vlservers.92 */93bool afs_select_vlserver(struct afs_vl_cursor *vc)94{95 struct afs_addr_list *alist = vc->alist;96 struct afs_vlserver *vlserver;97 unsigned long set, failed;98 unsigned int rtt;99 s32 abort_code = vc->call_abort_code;100 int error = vc->call_error, i;101 102 vc->nr_iterations++;103 104 _enter("VC=%x+%x,%d{%lx},%d{%lx},%d,%d",105 vc->debug_id, vc->nr_iterations, vc->server_index, vc->untried_servers,106 vc->addr_index, vc->addr_tried,107 error, abort_code);108 109 if (vc->flags & AFS_VL_CURSOR_STOP) {110 _leave(" = f [stopped]");111 return false;112 }113 114 if (vc->nr_iterations == 0)115 goto start;116 117 WRITE_ONCE(alist->addrs[vc->addr_index].last_error, error);118 119 /* Evaluate the result of the previous operation, if there was one. */120 switch (error) {121 default:122 case 0:123 /* Success or local failure. Stop. */124 vc->cumul_error.error = error;125 vc->flags |= AFS_VL_CURSOR_STOP;126 _leave(" = f [okay/local %d]", vc->cumul_error.error);127 return false;128 129 case -ECONNABORTED:130 /* The far side rejected the operation on some grounds. This131 * might involve the server being busy or the volume having been moved.132 */133 switch (abort_code) {134 case AFSVL_IO:135 case AFSVL_BADVOLOPER:136 case AFSVL_NOMEM:137 /* The server went weird. */138 afs_prioritise_error(&vc->cumul_error, -EREMOTEIO, abort_code);139 //write_lock(&vc->cell->vl_servers_lock);140 //vc->server_list->weird_mask |= 1 << vc->server_index;141 //write_unlock(&vc->cell->vl_servers_lock);142 goto next_server;143 144 default:145 afs_prioritise_error(&vc->cumul_error, error, abort_code);146 goto failed;147 }148 149 case -ERFKILL:150 case -EADDRNOTAVAIL:151 case -ENETUNREACH:152 case -EHOSTUNREACH:153 case -EHOSTDOWN:154 case -ECONNREFUSED:155 case -ETIMEDOUT:156 case -ETIME:157 _debug("no conn %d", error);158 afs_prioritise_error(&vc->cumul_error, error, 0);159 goto iterate_address;160 161 case -ECONNRESET:162 _debug("call reset");163 afs_prioritise_error(&vc->cumul_error, error, 0);164 vc->flags |= AFS_VL_CURSOR_RETRY;165 goto next_server;166 167 case -EOPNOTSUPP:168 _debug("notsupp");169 goto next_server;170 }171 172restart_from_beginning:173 _debug("restart");174 if (vc->call_responded &&175 vc->addr_index != vc->alist->preferred &&176 test_bit(alist->preferred, &vc->addr_tried))177 WRITE_ONCE(alist->preferred, vc->addr_index);178 afs_put_addrlist(alist, afs_alist_trace_put_vlrotate_restart);179 alist = vc->alist = NULL;180 181 afs_put_vlserverlist(vc->cell->net, vc->server_list);182 vc->server_list = NULL;183 if (vc->flags & AFS_VL_CURSOR_RETRIED)184 goto failed;185 vc->flags |= AFS_VL_CURSOR_RETRIED;186start:187 _debug("start");188 ASSERTCMP(alist, ==, NULL);189 190 if (!afs_start_vl_iteration(vc))191 goto failed;192 193 error = afs_send_vl_probes(vc->cell->net, vc->key, vc->server_list);194 if (error < 0) {195 afs_prioritise_error(&vc->cumul_error, error, 0);196 goto failed;197 }198 199pick_server:200 _debug("pick [%lx]", vc->untried_servers);201 ASSERTCMP(alist, ==, NULL);202 203 error = afs_wait_for_vl_probes(vc->server_list, vc->untried_servers);204 if (error < 0) {205 afs_prioritise_error(&vc->cumul_error, error, 0);206 goto failed;207 }208 209 /* Pick the untried server with the lowest RTT. */210 vc->server_index = vc->server_list->preferred;211 if (test_bit(vc->server_index, &vc->untried_servers))212 goto selected_server;213 214 vc->server_index = -1;215 rtt = UINT_MAX;216 for (i = 0; i < vc->server_list->nr_servers; i++) {217 struct afs_vlserver *s = vc->server_list->servers[i].server;218 219 if (!test_bit(i, &vc->untried_servers) ||220 !test_bit(AFS_VLSERVER_FL_RESPONDING, &s->flags))221 continue;222 if (s->probe.rtt <= rtt) {223 vc->server_index = i;224 rtt = s->probe.rtt;225 }226 }227 228 if (vc->server_index == -1)229 goto no_more_servers;230 231selected_server:232 _debug("use %d", vc->server_index);233 __clear_bit(vc->server_index, &vc->untried_servers);234 235 /* We're starting on a different vlserver from the list. We need to236 * check it, find its address list and probe its capabilities before we237 * use it.238 */239 vlserver = vc->server_list->servers[vc->server_index].server;240 vc->server = vlserver;241 242 _debug("USING VLSERVER: %s", vlserver->name);243 244 read_lock(&vlserver->lock);245 alist = rcu_dereference_protected(vlserver->addresses,246 lockdep_is_held(&vlserver->lock));247 vc->alist = afs_get_addrlist(alist, afs_alist_trace_get_vlrotate_set);248 read_unlock(&vlserver->lock);249 250 vc->addr_tried = 0;251 vc->addr_index = -1;252 253iterate_address:254 /* Iterate over the current server's address list to try and find an255 * address on which it will respond to us.256 */257 set = READ_ONCE(alist->responded);258 failed = READ_ONCE(alist->probe_failed);259 vc->addr_index = READ_ONCE(alist->preferred);260 261 _debug("%lx-%lx-%lx,%d", set, failed, vc->addr_tried, vc->addr_index);262 263 set &= ~(failed | vc->addr_tried);264 265 if (!set)266 goto next_server;267 268 if (!test_bit(vc->addr_index, &set))269 vc->addr_index = __ffs(set);270 271 set_bit(vc->addr_index, &vc->addr_tried);272 vc->alist = alist;273 274 _debug("VL address %d/%d", vc->addr_index, alist->nr_addrs);275 276 vc->call_responded = false;277 _leave(" = t %pISpc", rxrpc_kernel_remote_addr(alist->addrs[vc->addr_index].peer));278 return true;279 280next_server:281 _debug("next");282 ASSERT(alist);283 if (vc->call_responded &&284 vc->addr_index != alist->preferred &&285 test_bit(alist->preferred, &vc->addr_tried))286 WRITE_ONCE(alist->preferred, vc->addr_index);287 afs_put_addrlist(alist, afs_alist_trace_put_vlrotate_next);288 alist = vc->alist = NULL;289 goto pick_server;290 291no_more_servers:292 /* That's all the servers poked to no good effect. Try again if some293 * of them were busy.294 */295 if (vc->flags & AFS_VL_CURSOR_RETRY)296 goto restart_from_beginning;297 298 for (i = 0; i < vc->server_list->nr_servers; i++) {299 struct afs_vlserver *s = vc->server_list->servers[i].server;300 301 if (test_bit(AFS_VLSERVER_FL_RESPONDING, &s->flags))302 vc->cumul_error.responded = true;303 afs_prioritise_error(&vc->cumul_error, READ_ONCE(s->probe.error),304 s->probe.abort_code);305 }306 307failed:308 if (alist) {309 if (vc->call_responded &&310 vc->addr_index != alist->preferred &&311 test_bit(alist->preferred, &vc->addr_tried))312 WRITE_ONCE(alist->preferred, vc->addr_index);313 afs_put_addrlist(alist, afs_alist_trace_put_vlrotate_fail);314 alist = vc->alist = NULL;315 }316 vc->flags |= AFS_VL_CURSOR_STOP;317 _leave(" = f [failed %d]", vc->cumul_error.error);318 return false;319}320 321/*322 * Dump cursor state in the case of the error being EDESTADDRREQ.323 */324static void afs_vl_dump_edestaddrreq(const struct afs_vl_cursor *vc)325{326 struct afs_cell *cell = vc->cell;327 static int count;328 int i;329 330 if (!IS_ENABLED(CONFIG_AFS_DEBUG_CURSOR) || count > 3)331 return;332 count++;333 334 rcu_read_lock();335 pr_notice("EDESTADDR occurred\n");336 pr_notice("CELL: %s err=%d\n", cell->name, cell->error);337 pr_notice("DNS: src=%u st=%u lc=%x\n",338 cell->dns_source, cell->dns_status, cell->dns_lookup_count);339 pr_notice("VC: ut=%lx ix=%u ni=%hu fl=%hx err=%hd\n",340 vc->untried_servers, vc->server_index, vc->nr_iterations,341 vc->flags, vc->cumul_error.error);342 pr_notice("VC: call er=%d ac=%d r=%u\n",343 vc->call_error, vc->call_abort_code, vc->call_responded);344 345 if (vc->server_list) {346 const struct afs_vlserver_list *sl = vc->server_list;347 pr_notice("VC: SL nr=%u ix=%u\n",348 sl->nr_servers, sl->index);349 for (i = 0; i < sl->nr_servers; i++) {350 const struct afs_vlserver *s = sl->servers[i].server;351 pr_notice("VC: server %s+%hu fl=%lx E=%hd\n",352 s->name, s->port, s->flags, s->probe.error);353 if (s->addresses) {354 const struct afs_addr_list *a =355 rcu_dereference(s->addresses);356 pr_notice("VC: - nr=%u/%u/%u pf=%u\n",357 a->nr_ipv4, a->nr_addrs, a->max_addrs,358 a->preferred);359 pr_notice("VC: - R=%lx F=%lx\n",360 a->responded, a->probe_failed);361 if (a == vc->alist)362 pr_notice("VC: - current\n");363 }364 }365 }366 367 pr_notice("AC: t=%lx ax=%u\n", vc->addr_tried, vc->addr_index);368 rcu_read_unlock();369}370 371/*372 * Tidy up a volume location server cursor and unlock the vnode.373 */374int afs_end_vlserver_operation(struct afs_vl_cursor *vc)375{376 struct afs_net *net = vc->cell->net;377 378 _enter("VC=%x+%x", vc->debug_id, vc->nr_iterations);379 380 switch (vc->cumul_error.error) {381 case -EDESTADDRREQ:382 case -EADDRNOTAVAIL:383 case -ENETUNREACH:384 case -EHOSTUNREACH:385 afs_vl_dump_edestaddrreq(vc);386 break;387 }388 389 if (vc->alist) {390 if (vc->call_responded &&391 vc->addr_index != vc->alist->preferred &&392 test_bit(vc->alist->preferred, &vc->addr_tried))393 WRITE_ONCE(vc->alist->preferred, vc->addr_index);394 afs_put_addrlist(vc->alist, afs_alist_trace_put_vlrotate_end);395 vc->alist = NULL;396 }397 afs_put_vlserverlist(net, vc->server_list);398 return vc->cumul_error.error;399}400