1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 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 */ 17 bool afs_begin_vlserver_operation(struct afs_vl_cursor *vc, struct afs_cell *cell, 18 struct key *key) 19 { 20 memset(vc, 0, sizeof(*vc)); 21 vc->cell = cell; 22 vc->key = key; 23 vc->error = -EDESTADDRREQ; 24 vc->ac.error = SHRT_MAX; 25 26 if (signal_pending(current)) { 27 vc->error = -EINTR; 28 vc->flags |= AFS_VL_CURSOR_STOP; 29 return false; 30 } 31 32 return true; 33 } 34 35 /* 36 * Begin iteration through a server list, starting with the last used server if 37 * possible, or the last recorded good server if not. 38 */ 39 static bool afs_start_vl_iteration(struct afs_vl_cursor *vc) 40 { 41 struct afs_cell *cell = vc->cell; 42 unsigned int dns_lookup_count; 43 44 if (cell->dns_source == DNS_RECORD_UNAVAILABLE || 45 cell->dns_expiry <= ktime_get_real_seconds()) { 46 dns_lookup_count = smp_load_acquire(&cell->dns_lookup_count); 47 set_bit(AFS_CELL_FL_DO_LOOKUP, &cell->flags); 48 queue_work(afs_wq, &cell->manager); 49 50 if (cell->dns_source == DNS_RECORD_UNAVAILABLE) { 51 if (wait_var_event_interruptible( 52 &cell->dns_lookup_count, 53 smp_load_acquire(&cell->dns_lookup_count) 54 != dns_lookup_count) < 0) { 55 vc->error = -ERESTARTSYS; 56 return false; 57 } 58 } 59 60 /* Status load is ordered after lookup counter load */ 61 if (cell->dns_source == DNS_RECORD_UNAVAILABLE) { 62 vc->error = -EDESTADDRREQ; 63 return false; 64 } 65 } 66 67 read_lock(&cell->vl_servers_lock); 68 vc->server_list = afs_get_vlserverlist( 69 rcu_dereference_protected(cell->vl_servers, 70 lockdep_is_held(&cell->vl_servers_lock))); 71 read_unlock(&cell->vl_servers_lock); 72 if (!vc->server_list->nr_servers) 73 return false; 74 75 vc->untried = (1UL << vc->server_list->nr_servers) - 1; 76 vc->index = -1; 77 return true; 78 } 79 80 /* 81 * Select the vlserver to use. May be called multiple times to rotate 82 * through the vlservers. 83 */ 84 bool afs_select_vlserver(struct afs_vl_cursor *vc) 85 { 86 struct afs_addr_list *alist; 87 struct afs_vlserver *vlserver; 88 struct afs_error e; 89 u32 rtt; 90 int error = vc->ac.error, i; 91 92 _enter("%lx[%d],%lx[%d],%d,%d", 93 vc->untried, vc->index, 94 vc->ac.tried, vc->ac.index, 95 error, vc->ac.abort_code); 96 97 if (vc->flags & AFS_VL_CURSOR_STOP) { 98 _leave(" = f [stopped]"); 99 return false; 100 } 101 102 vc->nr_iterations++; 103 104 /* Evaluate the result of the previous operation, if there was one. */ 105 switch (error) { 106 case SHRT_MAX: 107 goto start; 108 109 default: 110 case 0: 111 /* Success or local failure. Stop. */ 112 vc->error = error; 113 vc->flags |= AFS_VL_CURSOR_STOP; 114 _leave(" = f [okay/local %d]", vc->ac.error); 115 return false; 116 117 case -ECONNABORTED: 118 /* The far side rejected the operation on some grounds. This 119 * might involve the server being busy or the volume having been moved. 120 */ 121 switch (vc->ac.abort_code) { 122 case AFSVL_IO: 123 case AFSVL_BADVOLOPER: 124 case AFSVL_NOMEM: 125 /* The server went weird. */ 126 vc->error = -EREMOTEIO; 127 //write_lock(&vc->cell->vl_servers_lock); 128 //vc->server_list->weird_mask |= 1 << vc->index; 129 //write_unlock(&vc->cell->vl_servers_lock); 130 goto next_server; 131 132 default: 133 vc->error = afs_abort_to_error(vc->ac.abort_code); 134 goto failed; 135 } 136 137 case -ERFKILL: 138 case -EADDRNOTAVAIL: 139 case -ENETUNREACH: 140 case -EHOSTUNREACH: 141 case -EHOSTDOWN: 142 case -ECONNREFUSED: 143 case -ETIMEDOUT: 144 case -ETIME: 145 _debug("no conn %d", error); 146 vc->error = error; 147 goto iterate_address; 148 149 case -ECONNRESET: 150 _debug("call reset"); 151 vc->error = error; 152 vc->flags |= AFS_VL_CURSOR_RETRY; 153 goto next_server; 154 } 155 156 restart_from_beginning: 157 _debug("restart"); 158 afs_end_cursor(&vc->ac); 159 afs_put_vlserverlist(vc->cell->net, vc->server_list); 160 vc->server_list = NULL; 161 if (vc->flags & AFS_VL_CURSOR_RETRIED) 162 goto failed; 163 vc->flags |= AFS_VL_CURSOR_RETRIED; 164 start: 165 _debug("start"); 166 167 if (!afs_start_vl_iteration(vc)) 168 goto failed; 169 170 error = afs_send_vl_probes(vc->cell->net, vc->key, vc->server_list); 171 if (error < 0) 172 goto failed_set_error; 173 174 pick_server: 175 _debug("pick [%lx]", vc->untried); 176 177 error = afs_wait_for_vl_probes(vc->server_list, vc->untried); 178 if (error < 0) 179 goto failed_set_error; 180 181 /* Pick the untried server with the lowest RTT. */ 182 vc->index = vc->server_list->preferred; 183 if (test_bit(vc->index, &vc->untried)) 184 goto selected_server; 185 186 vc->index = -1; 187 rtt = U32_MAX; 188 for (i = 0; i < vc->server_list->nr_servers; i++) { 189 struct afs_vlserver *s = vc->server_list->servers[i].server; 190 191 if (!test_bit(i, &vc->untried) || !s->probe.responded) 192 continue; 193 if (s->probe.rtt < rtt) { 194 vc->index = i; 195 rtt = s->probe.rtt; 196 } 197 } 198 199 if (vc->index == -1) 200 goto no_more_servers; 201 202 selected_server: 203 _debug("use %d", vc->index); 204 __clear_bit(vc->index, &vc->untried); 205 206 /* We're starting on a different vlserver from the list. We need to 207 * check it, find its address list and probe its capabilities before we 208 * use it. 209 */ 210 ASSERTCMP(vc->ac.alist, ==, NULL); 211 vlserver = vc->server_list->servers[vc->index].server; 212 vc->server = vlserver; 213 214 _debug("USING VLSERVER: %s", vlserver->name); 215 216 read_lock(&vlserver->lock); 217 alist = rcu_dereference_protected(vlserver->addresses, 218 lockdep_is_held(&vlserver->lock)); 219 afs_get_addrlist(alist); 220 read_unlock(&vlserver->lock); 221 222 memset(&vc->ac, 0, sizeof(vc->ac)); 223 224 if (!vc->ac.alist) 225 vc->ac.alist = alist; 226 else 227 afs_put_addrlist(alist); 228 229 vc->ac.index = -1; 230 231 iterate_address: 232 ASSERT(vc->ac.alist); 233 /* Iterate over the current server's address list to try and find an 234 * address on which it will respond to us. 235 */ 236 if (!afs_iterate_addresses(&vc->ac)) 237 goto next_server; 238 239 _debug("VL address %d/%d", vc->ac.index, vc->ac.alist->nr_addrs); 240 241 _leave(" = t %pISpc", &vc->ac.alist->addrs[vc->ac.index].transport); 242 return true; 243 244 next_server: 245 _debug("next"); 246 afs_end_cursor(&vc->ac); 247 goto pick_server; 248 249 no_more_servers: 250 /* That's all the servers poked to no good effect. Try again if some 251 * of them were busy. 252 */ 253 if (vc->flags & AFS_VL_CURSOR_RETRY) 254 goto restart_from_beginning; 255 256 e.error = -EDESTADDRREQ; 257 e.responded = false; 258 for (i = 0; i < vc->server_list->nr_servers; i++) { 259 struct afs_vlserver *s = vc->server_list->servers[i].server; 260 261 afs_prioritise_error(&e, READ_ONCE(s->probe.error), 262 s->probe.abort_code); 263 } 264 265 failed_set_error: 266 vc->error = error; 267 failed: 268 vc->flags |= AFS_VL_CURSOR_STOP; 269 afs_end_cursor(&vc->ac); 270 _leave(" = f [failed %d]", vc->error); 271 return false; 272 } 273 274 /* 275 * Dump cursor state in the case of the error being EDESTADDRREQ. 276 */ 277 static void afs_vl_dump_edestaddrreq(const struct afs_vl_cursor *vc) 278 { 279 static int count; 280 int i; 281 282 if (!IS_ENABLED(CONFIG_AFS_DEBUG_CURSOR) || count > 3) 283 return; 284 count++; 285 286 rcu_read_lock(); 287 pr_notice("EDESTADDR occurred\n"); 288 pr_notice("VC: ut=%lx ix=%u ni=%hu fl=%hx err=%hd\n", 289 vc->untried, vc->index, vc->nr_iterations, vc->flags, vc->error); 290 291 if (vc->server_list) { 292 const struct afs_vlserver_list *sl = vc->server_list; 293 pr_notice("VC: SL nr=%u ix=%u\n", 294 sl->nr_servers, sl->index); 295 for (i = 0; i < sl->nr_servers; i++) { 296 const struct afs_vlserver *s = sl->servers[i].server; 297 pr_notice("VC: server %s+%hu fl=%lx E=%hd\n", 298 s->name, s->port, s->flags, s->probe.error); 299 if (s->addresses) { 300 const struct afs_addr_list *a = 301 rcu_dereference(s->addresses); 302 pr_notice("VC: - nr=%u/%u/%u pf=%u\n", 303 a->nr_ipv4, a->nr_addrs, a->max_addrs, 304 a->preferred); 305 pr_notice("VC: - pr=%lx R=%lx F=%lx\n", 306 a->probed, a->responded, a->failed); 307 if (a == vc->ac.alist) 308 pr_notice("VC: - current\n"); 309 } 310 } 311 } 312 313 pr_notice("AC: t=%lx ax=%u ac=%d er=%d r=%u ni=%u\n", 314 vc->ac.tried, vc->ac.index, vc->ac.abort_code, vc->ac.error, 315 vc->ac.responded, vc->ac.nr_iterations); 316 rcu_read_unlock(); 317 } 318 319 /* 320 * Tidy up a volume location server cursor and unlock the vnode. 321 */ 322 int afs_end_vlserver_operation(struct afs_vl_cursor *vc) 323 { 324 struct afs_net *net = vc->cell->net; 325 326 if (vc->error == -EDESTADDRREQ || 327 vc->error == -EADDRNOTAVAIL || 328 vc->error == -ENETUNREACH || 329 vc->error == -EHOSTUNREACH) 330 afs_vl_dump_edestaddrreq(vc); 331 332 afs_end_cursor(&vc->ac); 333 afs_put_vlserverlist(net, vc->server_list); 334 335 if (vc->error == -ECONNABORTED) 336 vc->error = afs_abort_to_error(vc->ac.abort_code); 337 338 return vc->error; 339 } 340