xref: /linux/fs/afs/rotate.c (revision 8e3ed5440b0c305dcd1d5fa7419bd8066d22ef42)
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* Handle fileserver selection and rotation.
3  *
4  * Copyright (C) 2017 Red Hat, Inc. All Rights Reserved.
5  * Written by David Howells (dhowells@redhat.com)
6  */
7 
8 #include <linux/kernel.h>
9 #include <linux/slab.h>
10 #include <linux/fs.h>
11 #include <linux/sched.h>
12 #include <linux/delay.h>
13 #include <linux/sched/signal.h>
14 #include "internal.h"
15 #include "afs_fs.h"
16 #include "protocol_uae.h"
17 
18 void afs_clear_server_states(struct afs_operation *op)
19 {
20 	unsigned int i;
21 
22 	if (op->server_states) {
23 		for (i = 0; i < op->server_list->nr_servers; i++)
24 			afs_put_endpoint_state(op->server_states[i].endpoint_state,
25 					       afs_estate_trace_put_server_state);
26 		kfree(op->server_states);
27 	}
28 }
29 
30 /*
31  * Begin iteration through a server list, starting with the vnode's last used
32  * server if possible, or the last recorded good server if not.
33  */
34 static bool afs_start_fs_iteration(struct afs_operation *op,
35 				   struct afs_vnode *vnode)
36 {
37 	struct afs_server *server;
38 	void *cb_server;
39 	int i;
40 
41 	trace_afs_rotate(op, afs_rotate_trace_start, 0);
42 
43 	read_lock(&op->volume->servers_lock);
44 	op->server_list = afs_get_serverlist(
45 		rcu_dereference_protected(op->volume->servers,
46 					  lockdep_is_held(&op->volume->servers_lock)));
47 	read_unlock(&op->volume->servers_lock);
48 
49 	op->server_states = kcalloc(op->server_list->nr_servers, sizeof(op->server_states[0]),
50 				    GFP_KERNEL);
51 	if (!op->server_states) {
52 		afs_op_nomem(op);
53 		trace_afs_rotate(op, afs_rotate_trace_nomem, 0);
54 		return false;
55 	}
56 
57 	rcu_read_lock();
58 	for (i = 0; i < op->server_list->nr_servers; i++) {
59 		struct afs_endpoint_state *estate;
60 		struct afs_server_state *s = &op->server_states[i];
61 
62 		server = op->server_list->servers[i].server;
63 		estate = rcu_dereference(server->endpoint_state);
64 		s->endpoint_state = afs_get_endpoint_state(estate,
65 							   afs_estate_trace_get_server_state);
66 		s->probe_seq = estate->probe_seq;
67 		s->untried_addrs = (1UL << estate->addresses->nr_addrs) - 1;
68 		init_waitqueue_entry(&s->probe_waiter, current);
69 		afs_get_address_preferences(op->net, estate->addresses);
70 	}
71 	rcu_read_unlock();
72 
73 
74 	op->untried_servers = (1UL << op->server_list->nr_servers) - 1;
75 	op->server_index = -1;
76 
77 	cb_server = vnode->cb_server;
78 	if (cb_server) {
79 		/* See if the vnode's preferred record is still available */
80 		for (i = 0; i < op->server_list->nr_servers; i++) {
81 			server = op->server_list->servers[i].server;
82 			if (server == cb_server) {
83 				op->server_index = i;
84 				goto found_interest;
85 			}
86 		}
87 
88 		/* If we have a lock outstanding on a server that's no longer
89 		 * serving this vnode, then we can't switch to another server
90 		 * and have to return an error.
91 		 */
92 		if (op->flags & AFS_OPERATION_CUR_ONLY) {
93 			afs_op_set_error(op, -ESTALE);
94 			trace_afs_rotate(op, afs_rotate_trace_stale_lock, 0);
95 			return false;
96 		}
97 
98 		/* Note that the callback promise is effectively broken */
99 		write_seqlock(&vnode->cb_lock);
100 		ASSERTCMP(cb_server, ==, vnode->cb_server);
101 		vnode->cb_server = NULL;
102 		if (atomic64_xchg(&vnode->cb_expires_at, AFS_NO_CB_PROMISE) != AFS_NO_CB_PROMISE)
103 			vnode->cb_break++;
104 		write_sequnlock(&vnode->cb_lock);
105 	}
106 
107 found_interest:
108 	return true;
109 }
110 
111 /*
112  * Post volume busy note.
113  */
114 static void afs_busy(struct afs_operation *op, u32 abort_code)
115 {
116 	const char *m;
117 
118 	switch (abort_code) {
119 	case VOFFLINE:		m = "offline";		break;
120 	case VRESTARTING:	m = "restarting";	break;
121 	case VSALVAGING:	m = "being salvaged";	break;
122 	default:		m = "busy";		break;
123 	}
124 
125 	pr_notice("kAFS: Volume %llu '%s' on server %pU is %s\n",
126 		  op->volume->vid, op->volume->name, &op->server->uuid, m);
127 }
128 
129 /*
130  * Sleep and retry the operation to the same fileserver.
131  */
132 static bool afs_sleep_and_retry(struct afs_operation *op)
133 {
134 	trace_afs_rotate(op, afs_rotate_trace_busy_sleep, 0);
135 	if (!(op->flags & AFS_OPERATION_UNINTR)) {
136 		msleep_interruptible(1000);
137 		if (signal_pending(current)) {
138 			afs_op_set_error(op, -ERESTARTSYS);
139 			return false;
140 		}
141 	} else {
142 		msleep(1000);
143 	}
144 
145 	return true;
146 }
147 
148 /*
149  * Select the fileserver to use.  May be called multiple times to rotate
150  * through the fileservers.
151  */
152 bool afs_select_fileserver(struct afs_operation *op)
153 {
154 	struct afs_addr_list *alist;
155 	struct afs_server *server;
156 	struct afs_vnode *vnode = op->file[0].vnode;
157 	unsigned long set, failed;
158 	s32 abort_code = op->call_abort_code;
159 	int best_prio = 0;
160 	int error = op->call_error, addr_index, i, j;
161 
162 	op->nr_iterations++;
163 
164 	_enter("OP=%x+%x,%llx,%u{%lx},%u{%lx},%d,%d",
165 	       op->debug_id, op->nr_iterations, op->volume->vid,
166 	       op->server_index, op->untried_servers,
167 	       op->addr_index, op->addr_tried,
168 	       error, abort_code);
169 
170 	if (op->flags & AFS_OPERATION_STOP) {
171 		trace_afs_rotate(op, afs_rotate_trace_stopped, 0);
172 		_leave(" = f [stopped]");
173 		return false;
174 	}
175 
176 	if (op->nr_iterations == 0)
177 		goto start;
178 
179 	WRITE_ONCE(op->estate->addresses->addrs[op->addr_index].last_error, error);
180 	trace_afs_rotate(op, afs_rotate_trace_iter, op->call_error);
181 
182 	/* Evaluate the result of the previous operation, if there was one. */
183 	switch (op->call_error) {
184 	case 0:
185 		clear_bit(AFS_SE_VOLUME_OFFLINE,
186 			  &op->server_list->servers[op->server_index].flags);
187 		clear_bit(AFS_SE_VOLUME_BUSY,
188 			  &op->server_list->servers[op->server_index].flags);
189 		op->cumul_error.responded = true;
190 
191 		/* We succeeded, but we may need to redo the op from another
192 		 * server if we're looking at a set of RO volumes where some of
193 		 * the servers have not yet been brought up to date lest we
194 		 * regress the data.  We only switch to the new version once
195 		 * >=50% of the servers are updated.
196 		 */
197 		error = afs_update_volume_state(op);
198 		if (error != 0) {
199 			if (error == 1) {
200 				afs_sleep_and_retry(op);
201 				goto restart_from_beginning;
202 			}
203 			afs_op_set_error(op, error);
204 			goto failed;
205 		}
206 		fallthrough;
207 	default:
208 		/* Success or local failure.  Stop. */
209 		afs_op_set_error(op, error);
210 		op->flags |= AFS_OPERATION_STOP;
211 		trace_afs_rotate(op, afs_rotate_trace_stop, error);
212 		_leave(" = f [okay/local %d]", error);
213 		return false;
214 
215 	case -ECONNABORTED:
216 		/* The far side rejected the operation on some grounds.  This
217 		 * might involve the server being busy or the volume having been moved.
218 		 *
219 		 * Note that various V* errors should not be sent to a cache manager
220 		 * by a fileserver as they should be translated to more modern UAE*
221 		 * errors instead.  IBM AFS and OpenAFS fileservers, however, do leak
222 		 * these abort codes.
223 		 */
224 		trace_afs_rotate(op, afs_rotate_trace_aborted, abort_code);
225 		op->cumul_error.responded = true;
226 		switch (abort_code) {
227 		case VNOVOL:
228 			/* This fileserver doesn't know about the volume.
229 			 * - May indicate that the VL is wrong - retry once and compare
230 			 *   the results.
231 			 * - May indicate that the fileserver couldn't attach to the vol.
232 			 * - The volume might have been temporarily removed so that it can
233 			 *   be replaced by a volume restore.  "vos" might have ended one
234 			 *   transaction and has yet to create the next.
235 			 * - The volume might not be blessed or might not be in-service
236 			 *   (administrative action).
237 			 */
238 			if (op->flags & AFS_OPERATION_VNOVOL) {
239 				afs_op_accumulate_error(op, -EREMOTEIO, abort_code);
240 				goto next_server;
241 			}
242 
243 			write_lock(&op->volume->servers_lock);
244 			op->server_list->vnovol_mask |= 1 << op->server_index;
245 			write_unlock(&op->volume->servers_lock);
246 
247 			set_bit(AFS_VOLUME_NEEDS_UPDATE, &op->volume->flags);
248 			error = afs_check_volume_status(op->volume, op);
249 			if (error < 0) {
250 				afs_op_set_error(op, error);
251 				goto failed;
252 			}
253 
254 			if (test_bit(AFS_VOLUME_DELETED, &op->volume->flags)) {
255 				afs_op_set_error(op, -ENOMEDIUM);
256 				goto failed;
257 			}
258 
259 			/* If the server list didn't change, then assume that
260 			 * it's the fileserver having trouble.
261 			 */
262 			if (rcu_access_pointer(op->volume->servers) == op->server_list) {
263 				afs_op_accumulate_error(op, -EREMOTEIO, abort_code);
264 				goto next_server;
265 			}
266 
267 			/* Try again */
268 			op->flags |= AFS_OPERATION_VNOVOL;
269 			_leave(" = t [vnovol]");
270 			return true;
271 
272 		case VVOLEXISTS:
273 		case VONLINE:
274 			/* These should not be returned from the fileserver. */
275 			pr_warn("Fileserver returned unexpected abort %d\n",
276 				abort_code);
277 			afs_op_accumulate_error(op, -EREMOTEIO, abort_code);
278 			goto next_server;
279 
280 		case VNOSERVICE:
281 			/* Prior to AFS 3.2 VNOSERVICE was returned from the fileserver
282 			 * if the volume was neither in-service nor administratively
283 			 * blessed.  All usage was replaced by VNOVOL because AFS 3.1 and
284 			 * earlier cache managers did not handle VNOSERVICE and assumed
285 			 * it was the client OSes errno 105.
286 			 *
287 			 * Starting with OpenAFS 1.4.8 VNOSERVICE was repurposed as the
288 			 * fileserver idle dead time error which was sent in place of
289 			 * RX_CALL_TIMEOUT (-3).  The error was intended to be sent if the
290 			 * fileserver took too long to send a reply to the client.
291 			 * RX_CALL_TIMEOUT would have caused the cache manager to mark the
292 			 * server down whereas VNOSERVICE since AFS 3.2 would cause cache
293 			 * manager to temporarily (up to 15 minutes) mark the volume
294 			 * instance as unusable.
295 			 *
296 			 * The idle dead logic resulted in cache inconsistency since a
297 			 * state changing call that the cache manager assumed was dead
298 			 * could still be processed to completion by the fileserver.  This
299 			 * logic was removed in OpenAFS 1.8.0 and VNOSERVICE is no longer
300 			 * returned.  However, many 1.4.8 through 1.6.24 fileservers are
301 			 * still in existence.
302 			 *
303 			 * AuriStorFS fileservers have never returned VNOSERVICE.
304 			 *
305 			 * VNOSERVICE should be treated as an alias for RX_CALL_TIMEOUT.
306 			 */
307 		case RX_CALL_TIMEOUT:
308 			afs_op_accumulate_error(op, -ETIMEDOUT, abort_code);
309 			goto next_server;
310 
311 		case VSALVAGING: /* This error should not be leaked to cache managers
312 				  * but is from OpenAFS demand attach fileservers.
313 				  * It should be treated as an alias for VOFFLINE.
314 				  */
315 		case VSALVAGE: /* VSALVAGE should be treated as a synonym of VOFFLINE */
316 		case VOFFLINE:
317 			/* The volume is in use by the volserver or another volume utility
318 			 * for an operation that might alter the contents.  The volume is
319 			 * expected to come back but it might take a long time (could be
320 			 * days).
321 			 */
322 			if (!test_and_set_bit(AFS_SE_VOLUME_OFFLINE,
323 					      &op->server_list->servers[op->server_index].flags)) {
324 				afs_busy(op, abort_code);
325 				clear_bit(AFS_SE_VOLUME_BUSY,
326 					  &op->server_list->servers[op->server_index].flags);
327 			}
328 			if (op->flags & AFS_OPERATION_NO_VSLEEP) {
329 				afs_op_set_error(op, -EADV);
330 				goto failed;
331 			}
332 			goto busy;
333 
334 		case VRESTARTING: /* The fileserver is either shutting down or starting up. */
335 		case VBUSY:
336 			/* The volume is in use by the volserver or another volume
337 			 * utility for an operation that is not expected to alter the
338 			 * contents of the volume.  VBUSY does not need to be returned
339 			 * for a ROVOL or BACKVOL bound to an ITBusy volserver
340 			 * transaction.  The fileserver is permitted to continue serving
341 			 * content from ROVOLs and BACKVOLs during an ITBusy transaction
342 			 * because the content will not change.  However, many fileserver
343 			 * releases do return VBUSY for ROVOL and BACKVOL instances under
344 			 * many circumstances.
345 			 *
346 			 * Retry after going round all the servers unless we have a file
347 			 * lock we need to maintain.
348 			 */
349 			if (op->flags & AFS_OPERATION_NO_VSLEEP) {
350 				afs_op_set_error(op, -EBUSY);
351 				goto failed;
352 			}
353 			if (!test_and_set_bit(AFS_SE_VOLUME_BUSY,
354 					      &op->server_list->servers[op->server_index].flags)) {
355 				afs_busy(op, abort_code);
356 				clear_bit(AFS_SE_VOLUME_OFFLINE,
357 					  &op->server_list->servers[op->server_index].flags);
358 			}
359 		busy:
360 			if (op->flags & AFS_OPERATION_CUR_ONLY) {
361 				if (!afs_sleep_and_retry(op))
362 					goto failed;
363 
364 				/* Retry with same server & address */
365 				_leave(" = t [vbusy]");
366 				return true;
367 			}
368 
369 			op->flags |= AFS_OPERATION_VBUSY;
370 			goto next_server;
371 
372 		case VMOVED:
373 			/* The volume migrated to another server.  We consider
374 			 * consider all locks and callbacks broken and request
375 			 * an update from the VLDB.
376 			 *
377 			 * We also limit the number of VMOVED hops we will
378 			 * honour, just in case someone sets up a loop.
379 			 */
380 			if (op->flags & AFS_OPERATION_VMOVED) {
381 				afs_op_set_error(op, -EREMOTEIO);
382 				goto failed;
383 			}
384 			op->flags |= AFS_OPERATION_VMOVED;
385 
386 			set_bit(AFS_VOLUME_WAIT, &op->volume->flags);
387 			set_bit(AFS_VOLUME_NEEDS_UPDATE, &op->volume->flags);
388 			error = afs_check_volume_status(op->volume, op);
389 			if (error < 0) {
390 				afs_op_set_error(op, error);
391 				goto failed;
392 			}
393 
394 			/* If the server list didn't change, then the VLDB is
395 			 * out of sync with the fileservers.  This is hopefully
396 			 * a temporary condition, however, so we don't want to
397 			 * permanently block access to the file.
398 			 *
399 			 * TODO: Try other fileservers if we can.
400 			 *
401 			 * TODO: Retry a few times with sleeps.
402 			 */
403 			if (rcu_access_pointer(op->volume->servers) == op->server_list) {
404 				afs_op_accumulate_error(op, -ENOMEDIUM, abort_code);
405 				goto failed;
406 			}
407 
408 			goto restart_from_beginning;
409 
410 		case UAEIO:
411 		case VIO:
412 			afs_op_accumulate_error(op, -EREMOTEIO, abort_code);
413 			if (op->volume->type != AFSVL_RWVOL)
414 				goto next_server;
415 			goto failed;
416 
417 		case VDISKFULL:
418 		case UAENOSPC:
419 			/* The partition is full.  Only applies to RWVOLs.
420 			 * Translate locally and return ENOSPC.
421 			 * No replicas to failover to.
422 			 */
423 			afs_op_set_error(op, -ENOSPC);
424 			goto failed_but_online;
425 
426 		case VOVERQUOTA:
427 		case UAEDQUOT:
428 			/* Volume is full.  Only applies to RWVOLs.
429 			 * Translate locally and return EDQUOT.
430 			 * No replicas to failover to.
431 			 */
432 			afs_op_set_error(op, -EDQUOT);
433 			goto failed_but_online;
434 
435 		default:
436 			afs_op_accumulate_error(op, error, abort_code);
437 		failed_but_online:
438 			clear_bit(AFS_SE_VOLUME_OFFLINE,
439 				  &op->server_list->servers[op->server_index].flags);
440 			clear_bit(AFS_SE_VOLUME_BUSY,
441 				  &op->server_list->servers[op->server_index].flags);
442 			goto failed;
443 		}
444 
445 	case -ETIMEDOUT:
446 	case -ETIME:
447 		if (afs_op_error(op) != -EDESTADDRREQ)
448 			goto iterate_address;
449 		fallthrough;
450 	case -ERFKILL:
451 	case -EADDRNOTAVAIL:
452 	case -ENETUNREACH:
453 	case -EHOSTUNREACH:
454 	case -EHOSTDOWN:
455 	case -ECONNREFUSED:
456 		_debug("no conn");
457 		afs_op_accumulate_error(op, error, 0);
458 		goto iterate_address;
459 
460 	case -ENETRESET:
461 		pr_warn("kAFS: Peer reset %s (op=%x)\n",
462 			op->type ? op->type->name : "???", op->debug_id);
463 		fallthrough;
464 	case -ECONNRESET:
465 		_debug("call reset");
466 		afs_op_set_error(op, error);
467 		goto failed;
468 	}
469 
470 restart_from_beginning:
471 	trace_afs_rotate(op, afs_rotate_trace_restart, 0);
472 	_debug("restart");
473 	op->estate = NULL;
474 	op->server = NULL;
475 	afs_clear_server_states(op);
476 	op->server_states = NULL;
477 	afs_put_serverlist(op->net, op->server_list);
478 	op->server_list = NULL;
479 start:
480 	_debug("start");
481 	ASSERTCMP(op->estate, ==, NULL);
482 	/* See if we need to do an update of the volume record.  Note that the
483 	 * volume may have moved or even have been deleted.
484 	 */
485 	error = afs_check_volume_status(op->volume, op);
486 	trace_afs_rotate(op, afs_rotate_trace_check_vol_status, error);
487 	if (error < 0) {
488 		afs_op_set_error(op, error);
489 		goto failed;
490 	}
491 
492 	if (!afs_start_fs_iteration(op, vnode))
493 		goto failed;
494 
495 	_debug("__ VOL %llx __", op->volume->vid);
496 
497 pick_server:
498 	_debug("pick [%lx]", op->untried_servers);
499 	ASSERTCMP(op->estate, ==, NULL);
500 
501 	error = afs_wait_for_fs_probes(op, op->server_states,
502 				       !(op->flags & AFS_OPERATION_UNINTR));
503 	switch (error) {
504 	case 0: /* No untried responsive servers and no outstanding probes */
505 		trace_afs_rotate(op, afs_rotate_trace_probe_none, 0);
506 		goto no_more_servers;
507 	case 1: /* Got a response */
508 		trace_afs_rotate(op, afs_rotate_trace_probe_response, 0);
509 		break;
510 	case 2: /* Probe data superseded */
511 		trace_afs_rotate(op, afs_rotate_trace_probe_superseded, 0);
512 		goto restart_from_beginning;
513 	default:
514 		trace_afs_rotate(op, afs_rotate_trace_probe_error, error);
515 		afs_op_set_error(op, error);
516 		goto failed;
517 	}
518 
519 	/* Pick the untried server with the highest priority untried endpoint.
520 	 * If we have outstanding callbacks, we stick with the server we're
521 	 * already using if we can.
522 	 */
523 	if (op->server) {
524 		_debug("server %u", op->server_index);
525 		if (test_bit(op->server_index, &op->untried_servers))
526 			goto selected_server;
527 		op->server = NULL;
528 		_debug("no server");
529 	}
530 
531 	rcu_read_lock();
532 	op->server_index = -1;
533 	best_prio = -1;
534 	for (i = 0; i < op->server_list->nr_servers; i++) {
535 		struct afs_endpoint_state *es;
536 		struct afs_server_entry *se = &op->server_list->servers[i];
537 		struct afs_addr_list *sal;
538 		struct afs_server *s = se->server;
539 
540 		if (!test_bit(i, &op->untried_servers) ||
541 		    test_bit(AFS_SE_EXCLUDED, &se->flags) ||
542 		    !test_bit(AFS_SERVER_FL_RESPONDING, &s->flags))
543 			continue;
544 		es = op->server_states->endpoint_state;
545 		sal = es->addresses;
546 
547 		afs_get_address_preferences_rcu(op->net, sal);
548 		for (j = 0; j < sal->nr_addrs; j++) {
549 			if (!sal->addrs[j].peer)
550 				continue;
551 			if (sal->addrs[j].prio > best_prio) {
552 				op->server_index = i;
553 				best_prio = sal->addrs[j].prio;
554 			}
555 		}
556 	}
557 	rcu_read_unlock();
558 
559 	if (op->server_index == -1)
560 		goto no_more_servers;
561 
562 selected_server:
563 	trace_afs_rotate(op, afs_rotate_trace_selected_server, best_prio);
564 	_debug("use %d prio %u", op->server_index, best_prio);
565 	__clear_bit(op->server_index, &op->untried_servers);
566 
567 	/* We're starting on a different fileserver from the list.  We need to
568 	 * check it, create a callback intercept, find its address list and
569 	 * probe its capabilities before we use it.
570 	 */
571 	ASSERTCMP(op->estate, ==, NULL);
572 	server = op->server_list->servers[op->server_index].server;
573 
574 	if (!afs_check_server_record(op, server, op->key))
575 		goto failed;
576 
577 	_debug("USING SERVER: %pU", &server->uuid);
578 
579 	op->flags |= AFS_OPERATION_RETRY_SERVER;
580 	op->server = server;
581 	if (vnode->cb_server != server) {
582 		vnode->cb_server = server;
583 		vnode->cb_v_check = atomic_read(&vnode->volume->cb_v_break);
584 		atomic64_set(&vnode->cb_expires_at, AFS_NO_CB_PROMISE);
585 	}
586 
587 retry_server:
588 	op->addr_tried = 0;
589 	op->addr_index = -1;
590 
591 iterate_address:
592 	/* Iterate over the current server's address list to try and find an
593 	 * address on which it will respond to us.
594 	 */
595 	op->estate = op->server_states[op->server_index].endpoint_state;
596 	set = READ_ONCE(op->estate->responsive_set);
597 	failed = READ_ONCE(op->estate->failed_set);
598 	_debug("iterate ES=%x rs=%lx fs=%lx", op->estate->probe_seq, set, failed);
599 	set &= ~(failed | op->addr_tried);
600 	trace_afs_rotate(op, afs_rotate_trace_iterate_addr, set);
601 	if (!set)
602 		goto wait_for_more_probe_results;
603 
604 	alist = op->estate->addresses;
605 	for (i = 0; i < alist->nr_addrs; i++) {
606 		if (alist->addrs[i].prio > best_prio) {
607 			addr_index = i;
608 			best_prio = alist->addrs[i].prio;
609 		}
610 	}
611 
612 	addr_index = READ_ONCE(alist->preferred);
613 	if (!test_bit(addr_index, &set))
614 		addr_index = __ffs(set);
615 
616 	op->addr_index = addr_index;
617 	set_bit(addr_index, &op->addr_tried);
618 
619 	op->volsync.creation = TIME64_MIN;
620 	op->volsync.update = TIME64_MIN;
621 	op->call_responded = false;
622 	_debug("address [%u] %u/%u %pISp",
623 	       op->server_index, addr_index, alist->nr_addrs,
624 	       rxrpc_kernel_remote_addr(alist->addrs[op->addr_index].peer));
625 	_leave(" = t");
626 	return true;
627 
628 wait_for_more_probe_results:
629 	error = afs_wait_for_one_fs_probe(op->server, op->estate, op->addr_tried,
630 					  !(op->flags & AFS_OPERATION_UNINTR));
631 	if (!error)
632 		goto iterate_address;
633 
634 	/* We've now had a failure to respond on all of a server's addresses -
635 	 * immediately probe them again and consider retrying the server.
636 	 */
637 	trace_afs_rotate(op, afs_rotate_trace_probe_fileserver, 0);
638 	afs_probe_fileserver(op->net, op->server);
639 	if (op->flags & AFS_OPERATION_RETRY_SERVER) {
640 		error = afs_wait_for_one_fs_probe(op->server, op->estate, op->addr_tried,
641 						  !(op->flags & AFS_OPERATION_UNINTR));
642 		switch (error) {
643 		case 0:
644 			op->flags &= ~AFS_OPERATION_RETRY_SERVER;
645 			trace_afs_rotate(op, afs_rotate_trace_retry_server, 0);
646 			goto retry_server;
647 		case -ERESTARTSYS:
648 			afs_op_set_error(op, error);
649 			goto failed;
650 		case -ETIME:
651 		case -EDESTADDRREQ:
652 			goto next_server;
653 		}
654 	}
655 
656 next_server:
657 	trace_afs_rotate(op, afs_rotate_trace_next_server, 0);
658 	_debug("next");
659 	ASSERT(op->estate);
660 	alist = op->estate->addresses;
661 	if (op->call_responded &&
662 	    op->addr_index != READ_ONCE(alist->preferred) &&
663 	    test_bit(alist->preferred, &op->addr_tried))
664 		WRITE_ONCE(alist->preferred, op->addr_index);
665 	op->estate = NULL;
666 	goto pick_server;
667 
668 no_more_servers:
669 	/* That's all the servers poked to no good effect.  Try again if some
670 	 * of them were busy.
671 	 */
672 	trace_afs_rotate(op, afs_rotate_trace_no_more_servers, 0);
673 	if (op->flags & AFS_OPERATION_VBUSY) {
674 		afs_sleep_and_retry(op);
675 		op->flags &= ~AFS_OPERATION_VBUSY;
676 		goto restart_from_beginning;
677 	}
678 
679 	rcu_read_lock();
680 	for (i = 0; i < op->server_list->nr_servers; i++) {
681 		struct afs_endpoint_state *estate;
682 
683 		estate = op->server_states->endpoint_state;
684 		error = READ_ONCE(estate->error);
685 		if (error < 0)
686 			afs_op_accumulate_error(op, error, estate->abort_code);
687 	}
688 	rcu_read_unlock();
689 
690 failed:
691 	trace_afs_rotate(op, afs_rotate_trace_failed, 0);
692 	op->flags |= AFS_OPERATION_STOP;
693 	if (op->estate) {
694 		alist = op->estate->addresses;
695 		if (op->call_responded &&
696 		    op->addr_index != READ_ONCE(alist->preferred) &&
697 		    test_bit(alist->preferred, &op->addr_tried))
698 			WRITE_ONCE(alist->preferred, op->addr_index);
699 		op->estate = NULL;
700 	}
701 	_leave(" = f [failed %d]", afs_op_error(op));
702 	return false;
703 }
704 
705 /*
706  * Dump cursor state in the case of the error being EDESTADDRREQ.
707  */
708 void afs_dump_edestaddrreq(const struct afs_operation *op)
709 {
710 	static int count;
711 	int i;
712 
713 	if (!IS_ENABLED(CONFIG_AFS_DEBUG_CURSOR) || count > 3)
714 		return;
715 	count++;
716 
717 	rcu_read_lock();
718 
719 	pr_notice("EDESTADDR occurred\n");
720 	pr_notice("OP: cbb=%x cbb2=%x fl=%x err=%hd\n",
721 		  op->file[0].cb_break_before,
722 		  op->file[1].cb_break_before, op->flags, op->cumul_error.error);
723 	pr_notice("OP: ut=%lx ix=%d ni=%u\n",
724 		  op->untried_servers, op->server_index, op->nr_iterations);
725 	pr_notice("OP: call  er=%d ac=%d r=%u\n",
726 		  op->call_error, op->call_abort_code, op->call_responded);
727 
728 	if (op->server_list) {
729 		const struct afs_server_list *sl = op->server_list;
730 
731 		pr_notice("FC: SL nr=%u vnov=%hx\n",
732 			  sl->nr_servers, sl->vnovol_mask);
733 		for (i = 0; i < sl->nr_servers; i++) {
734 			const struct afs_server *s = sl->servers[i].server;
735 			const struct afs_endpoint_state *e =
736 				rcu_dereference(s->endpoint_state);
737 			const struct afs_addr_list *a = e->addresses;
738 
739 			pr_notice("FC: server fl=%lx av=%u %pU\n",
740 				  s->flags, s->addr_version, &s->uuid);
741 			pr_notice("FC:  - pq=%x R=%lx F=%lx\n",
742 				  e->probe_seq, e->responsive_set, e->failed_set);
743 			if (a) {
744 				pr_notice("FC:  - av=%u nr=%u/%u/%u pr=%u\n",
745 					  a->version,
746 					  a->nr_ipv4, a->nr_addrs, a->max_addrs,
747 					  a->preferred);
748 				if (a == e->addresses)
749 					pr_notice("FC:  - current\n");
750 			}
751 		}
752 	}
753 
754 	pr_notice("AC: t=%lx ax=%d\n", op->addr_tried, op->addr_index);
755 	rcu_read_unlock();
756 }
757