fs_probe.c

  1// SPDX-License-Identifier: GPL-2.0-or-later
  2/* AFS fileserver probing
  3 *
  4 * Copyright (C) 2018, 2020 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_afs.h"
 13#include "protocol_yfs.h"
 14
 15static unsigned int afs_fs_probe_fast_poll_interval = 30 * HZ;
 16static unsigned int afs_fs_probe_slow_poll_interval = 5 * 60 * HZ;
 17
 18struct afs_endpoint_state *afs_get_endpoint_state(struct afs_endpoint_state *estate,
 19						  enum afs_estate_trace where)
 20{
 21	if (estate) {
 22		int r;
 23
 24		__refcount_inc(&estate->ref, &r);
 25		trace_afs_estate(estate->server_id, estate->probe_seq, r, where);
 26	}
 27	return estate;
 28}
 29
 30static void afs_endpoint_state_rcu(struct rcu_head *rcu)
 31{
 32	struct afs_endpoint_state *estate = container_of(rcu, struct afs_endpoint_state, rcu);
 33
 34	trace_afs_estate(estate->server_id, estate->probe_seq, refcount_read(&estate->ref),
 35			 afs_estate_trace_free);
 36	afs_put_addrlist(estate->addresses, afs_alist_trace_put_estate);
 37	kfree(estate);
 38}
 39
 40void afs_put_endpoint_state(struct afs_endpoint_state *estate, enum afs_estate_trace where)
 41{
 42	if (estate) {
 43		unsigned int server_id = estate->server_id, probe_seq = estate->probe_seq;
 44		bool dead;
 45		int r;
 46
 47		dead = __refcount_dec_and_test(&estate->ref, &r);
 48		trace_afs_estate(server_id, probe_seq, r, where);
 49		if (dead)
 50			call_rcu(&estate->rcu, afs_endpoint_state_rcu);
 51	}
 52}
 53
 54/*
 55 * Start the probe polling timer.  We have to supply it with an inc on the
 56 * outstanding server count.
 57 */
 58static void afs_schedule_fs_probe(struct afs_net *net,
 59				  struct afs_server *server, bool fast)
 60{
 61	unsigned long atj;
 62
 63	if (!net->live)
 64		return;
 65
 66	atj = server->probed_at;
 67	atj += fast ? afs_fs_probe_fast_poll_interval : afs_fs_probe_slow_poll_interval;
 68
 69	afs_inc_servers_outstanding(net);
 70	if (timer_reduce(&net->fs_probe_timer, atj))
 71		afs_dec_servers_outstanding(net);
 72}
 73
 74/*
 75 * Handle the completion of a set of probes.
 76 */
 77static void afs_finished_fs_probe(struct afs_net *net, struct afs_server *server,
 78				  struct afs_endpoint_state *estate)
 79{
 80	bool responded = test_bit(AFS_ESTATE_RESPONDED, &estate->flags);
 81
 82	write_seqlock(&net->fs_lock);
 83	if (responded) {
 84		list_add_tail(&server->probe_link, &net->fs_probe_slow);
 85	} else {
 86		server->rtt = UINT_MAX;
 87		clear_bit(AFS_SERVER_FL_RESPONDING, &server->flags);
 88		list_add_tail(&server->probe_link, &net->fs_probe_fast);
 89	}
 90
 91	write_sequnlock(&net->fs_lock);
 92
 93	afs_schedule_fs_probe(net, server, !responded);
 94}
 95
 96/*
 97 * Handle the completion of a probe.
 98 */
 99static void afs_done_one_fs_probe(struct afs_net *net, struct afs_server *server,
100				  struct afs_endpoint_state *estate)
101{
102	_enter("");
103
104	if (atomic_dec_and_test(&estate->nr_probing))
105		afs_finished_fs_probe(net, server, estate);
106
107	wake_up_all(&server->probe_wq);
108}
109
110/*
111 * Handle inability to send a probe due to ENOMEM when trying to allocate a
112 * call struct.
113 */
114static void afs_fs_probe_not_done(struct afs_net *net,
115				  struct afs_server *server,
116				  struct afs_endpoint_state *estate,
117				  int index)
118{
119	_enter("");
120
121	trace_afs_io_error(0, -ENOMEM, afs_io_error_fs_probe_fail);
122	spin_lock(&server->probe_lock);
123
124	set_bit(AFS_ESTATE_LOCAL_FAILURE, &estate->flags);
125	if (estate->error == 0)
126		estate->error = -ENOMEM;
127
128	set_bit(index, &estate->failed_set);
129
130	spin_unlock(&server->probe_lock);
131	return afs_done_one_fs_probe(net, server, estate);
132}
133
134/*
135 * Process the result of probing a fileserver.  This is called after successful
136 * or failed delivery of an FS.GetCapabilities operation.
137 */
138void afs_fileserver_probe_result(struct afs_call *call)
139{
140	struct afs_endpoint_state *estate = call->probe;
141	struct afs_addr_list *alist = estate->addresses;
142	struct afs_address *addr = &alist->addrs[call->probe_index];
143	struct afs_server *server = call->server;
144	unsigned int index = call->probe_index;
145	unsigned int rtt_us = -1, cap0;
146	int ret = call->error;
147
148	_enter("%pU,%u", &server->uuid, index);
149
150	WRITE_ONCE(addr->last_error, ret);
151
152	spin_lock(&server->probe_lock);
153
154	switch (ret) {
155	case 0:
156		estate->error = 0;
157		goto responded;
158	case -ECONNABORTED:
159		if (!test_bit(AFS_ESTATE_RESPONDED, &estate->flags)) {
160			estate->abort_code = call->abort_code;
161			estate->error = ret;
162		}
163		goto responded;
164	case -ENOMEM:
165	case -ENONET:
166		clear_bit(index, &estate->responsive_set);
167		set_bit(AFS_ESTATE_LOCAL_FAILURE, &estate->flags);
168		trace_afs_io_error(call->debug_id, ret, afs_io_error_fs_probe_fail);
169		goto out;
170	case -ECONNRESET: /* Responded, but call expired. */
171	case -ERFKILL:
172	case -EADDRNOTAVAIL:
173	case -ENETUNREACH:
174	case -EHOSTUNREACH:
175	case -EHOSTDOWN:
176	case -ECONNREFUSED:
177	case -ETIMEDOUT:
178	case -ETIME:
179	default:
180		clear_bit(index, &estate->responsive_set);
181		set_bit(index, &estate->failed_set);
182		if (!test_bit(AFS_ESTATE_RESPONDED, &estate->flags) &&
183		    (estate->error == 0 ||
184		     estate->error == -ETIMEDOUT ||
185		     estate->error == -ETIME))
186			estate->error = ret;
187		trace_afs_io_error(call->debug_id, ret, afs_io_error_fs_probe_fail);
188		goto out;
189	}
190
191responded:
192	clear_bit(index, &estate->failed_set);
193
194	if (call->service_id == YFS_FS_SERVICE) {
195		set_bit(AFS_ESTATE_IS_YFS, &estate->flags);
196		set_bit(AFS_SERVER_FL_IS_YFS, &server->flags);
197		server->service_id = call->service_id;
198	} else {
199		set_bit(AFS_ESTATE_NOT_YFS, &estate->flags);
200		if (!test_bit(AFS_ESTATE_IS_YFS, &estate->flags)) {
201			clear_bit(AFS_SERVER_FL_IS_YFS, &server->flags);
202			server->service_id = call->service_id;
203		}
204		cap0 = ntohl(call->tmp);
205		if (cap0 & AFS3_VICED_CAPABILITY_64BITFILES)
206			set_bit(AFS_SERVER_FL_HAS_FS64, &server->flags);
207		else
208			clear_bit(AFS_SERVER_FL_HAS_FS64, &server->flags);
209	}
210
211	rtt_us = rxrpc_kernel_get_srtt(addr->peer);
212	if (rtt_us < estate->rtt) {
213		estate->rtt = rtt_us;
214		server->rtt = rtt_us;
215		alist->preferred = index;
216	}
217
218	smp_wmb(); /* Set rtt before responded. */
219	set_bit(AFS_ESTATE_RESPONDED, &estate->flags);
220	set_bit(index, &estate->responsive_set);
221	set_bit(AFS_SERVER_FL_RESPONDING, &server->flags);
222out:
223	spin_unlock(&server->probe_lock);
224
225	trace_afs_fs_probe(server, false, estate, index, call->error, call->abort_code, rtt_us);
226	_debug("probe[%x] %pU [%u] %pISpc rtt=%d ret=%d",
227	       estate->probe_seq, &server->uuid, index,
228	       rxrpc_kernel_remote_addr(alist->addrs[index].peer),
229	       rtt_us, ret);
230
231	return afs_done_one_fs_probe(call->net, server, estate);
232}
233
234/*
235 * Probe all of a fileserver's addresses to find out the best route and to
236 * query its capabilities.
237 */
238int afs_fs_probe_fileserver(struct afs_net *net, struct afs_server *server,
239			    struct afs_addr_list *new_alist, struct key *key)
240{
241	struct afs_endpoint_state *estate, *old;
242	struct afs_addr_list *old_alist = NULL, *alist;
243	unsigned long unprobed;
244
245	_enter("%pU", &server->uuid);
246
247	estate = kzalloc(sizeof(*estate), GFP_KERNEL);
248	if (!estate)
249		return -ENOMEM;
250
251	refcount_set(&estate->ref, 2);
252	estate->server_id = server->debug_id;
253	estate->rtt = UINT_MAX;
254
255	write_lock(&server->fs_lock);
256
257	old = rcu_dereference_protected(server->endpoint_state,
258					lockdep_is_held(&server->fs_lock));
259	if (old) {
260		estate->responsive_set = old->responsive_set;
261		if (!new_alist)
262			new_alist = old->addresses;
263	}
264
265	if (old_alist != new_alist)
266		afs_set_peer_appdata(server, old_alist, new_alist);
267
268	estate->addresses = afs_get_addrlist(new_alist, afs_alist_trace_get_estate);
269	alist = estate->addresses;
270	estate->probe_seq = ++server->probe_counter;
271	atomic_set(&estate->nr_probing, alist->nr_addrs);
272
273	if (new_alist)
274		server->addr_version = new_alist->version;
275	rcu_assign_pointer(server->endpoint_state, estate);
276	write_unlock(&server->fs_lock);
277	if (old)
278		set_bit(AFS_ESTATE_SUPERSEDED, &old->flags);
279
280	trace_afs_estate(estate->server_id, estate->probe_seq, refcount_read(&estate->ref),
281			 afs_estate_trace_alloc_probe);
282
283	afs_get_address_preferences(net, new_alist);
284
285	server->probed_at = jiffies;
286	unprobed = (1UL << alist->nr_addrs) - 1;
287	while (unprobed) {
288		unsigned int index = 0, i;
289		int best_prio = -1;
290
291		for (i = 0; i < alist->nr_addrs; i++) {
292			if (test_bit(i, &unprobed) &&
293			    alist->addrs[i].prio > best_prio) {
294				index = i;
295				best_prio = alist->addrs[i].prio;
296			}
297		}
298		__clear_bit(index, &unprobed);
299
300		trace_afs_fs_probe(server, true, estate, index, 0, 0, 0);
301		if (!afs_fs_get_capabilities(net, server, estate, index, key))
302			afs_fs_probe_not_done(net, server, estate, index);
303	}
304
305	afs_put_endpoint_state(old, afs_estate_trace_put_probe);
306	afs_put_endpoint_state(estate, afs_estate_trace_put_probe);
307	return 0;
308}
309
310/*
311 * Wait for the first as-yet untried fileserver to respond, for the probe state
312 * to be superseded or for all probes to finish.
313 */
314int afs_wait_for_fs_probes(struct afs_operation *op, struct afs_server_state *states, bool intr)
315{
316	struct afs_endpoint_state *estate;
317	struct afs_server_list *slist = op->server_list;
318	bool still_probing = true;
319	int ret = 0, i;
320
321	_enter("%u", slist->nr_servers);
322
323	for (i = 0; i < slist->nr_servers; i++) {
324		estate = states[i].endpoint_state;
325		if (test_bit(AFS_ESTATE_SUPERSEDED, &estate->flags))
326			return 2;
327		if (atomic_read(&estate->nr_probing))
328			still_probing = true;
329		if (estate->responsive_set & states[i].untried_addrs)
330			return 1;
331	}
332	if (!still_probing)
333		return 0;
334
335	for (i = 0; i < slist->nr_servers; i++)
336		add_wait_queue(&slist->servers[i].server->probe_wq, &states[i].probe_waiter);
337
338	for (;;) {
339		still_probing = false;
340
341		set_current_state(intr ? TASK_INTERRUPTIBLE : TASK_UNINTERRUPTIBLE);
342		for (i = 0; i < slist->nr_servers; i++) {
343			estate = states[i].endpoint_state;
344			if (test_bit(AFS_ESTATE_SUPERSEDED, &estate->flags)) {
345				ret = 2;
346				goto stop;
347			}
348			if (atomic_read(&estate->nr_probing))
349				still_probing = true;
350			if (estate->responsive_set & states[i].untried_addrs) {
351				ret = 1;
352				goto stop;
353			}
354		}
355
356		if (!still_probing || signal_pending(current))
357			goto stop;
358		schedule();
359	}
360
361stop:
362	set_current_state(TASK_RUNNING);
363
364	for (i = 0; i < slist->nr_servers; i++)
365		remove_wait_queue(&slist->servers[i].server->probe_wq, &states[i].probe_waiter);
366
367	if (!ret && signal_pending(current))
368		ret = -ERESTARTSYS;
369	return ret;
370}
371
372/*
373 * Probe timer.  We have an increment on fs_outstanding that we need to pass
374 * along to the work item.
375 */
376void afs_fs_probe_timer(struct timer_list *timer)
377{
378	struct afs_net *net = container_of(timer, struct afs_net, fs_probe_timer);
379
380	if (!net->live || !queue_work(afs_wq, &net->fs_prober))
381		afs_dec_servers_outstanding(net);
382}
383
384/*
385 * Dispatch a probe to a server.
386 */
387static void afs_dispatch_fs_probe(struct afs_net *net, struct afs_server *server)
388	__releases(&net->fs_lock)
389{
390	struct key *key = NULL;
391
392	/* We remove it from the queues here - it will be added back to
393	 * one of the queues on the completion of the probe.
394	 */
395	list_del_init(&server->probe_link);
396
397	afs_get_server(server, afs_server_trace_get_probe);
398	write_sequnlock(&net->fs_lock);
399
400	afs_fs_probe_fileserver(net, server, NULL, key);
401	afs_put_server(net, server, afs_server_trace_put_probe);
402}
403
404/*
405 * Probe a server immediately without waiting for its due time to come
406 * round.  This is used when all of the addresses have been tried.
407 */
408void afs_probe_fileserver(struct afs_net *net, struct afs_server *server)
409{
410	write_seqlock(&net->fs_lock);
411	if (!list_empty(&server->probe_link))
412		return afs_dispatch_fs_probe(net, server);
413	write_sequnlock(&net->fs_lock);
414}
415
416/*
417 * Probe dispatcher to regularly dispatch probes to keep NAT alive.
418 */
419void afs_fs_probe_dispatcher(struct work_struct *work)
420{
421	struct afs_net *net = container_of(work, struct afs_net, fs_prober);
422	struct afs_server *fast, *slow, *server;
423	unsigned long nowj, timer_at, poll_at;
424	bool first_pass = true, set_timer = false;
425
426	if (!net->live) {
427		afs_dec_servers_outstanding(net);
428		return;
429	}
430
431	_enter("");
432
433	if (list_empty(&net->fs_probe_fast) && list_empty(&net->fs_probe_slow)) {
434		afs_dec_servers_outstanding(net);
435		_leave(" [none]");
436		return;
437	}
438
439again:
440	write_seqlock(&net->fs_lock);
441
442	fast = slow = server = NULL;
443	nowj = jiffies;
444	timer_at = nowj + MAX_JIFFY_OFFSET;
445
446	if (!list_empty(&net->fs_probe_fast)) {
447		fast = list_first_entry(&net->fs_probe_fast, struct afs_server, probe_link);
448		poll_at = fast->probed_at + afs_fs_probe_fast_poll_interval;
449		if (time_before(nowj, poll_at)) {
450			timer_at = poll_at;
451			set_timer = true;
452			fast = NULL;
453		}
454	}
455
456	if (!list_empty(&net->fs_probe_slow)) {
457		slow = list_first_entry(&net->fs_probe_slow, struct afs_server, probe_link);
458		poll_at = slow->probed_at + afs_fs_probe_slow_poll_interval;
459		if (time_before(nowj, poll_at)) {
460			if (time_before(poll_at, timer_at))
461			    timer_at = poll_at;
462			set_timer = true;
463			slow = NULL;
464		}
465	}
466
467	server = fast ?: slow;
468	if (server)
469		_debug("probe %pU", &server->uuid);
470
471	if (server && (first_pass || !need_resched())) {
472		afs_dispatch_fs_probe(net, server);
473		first_pass = false;
474		goto again;
475	}
476
477	write_sequnlock(&net->fs_lock);
478
479	if (server) {
480		if (!queue_work(afs_wq, &net->fs_prober))
481			afs_dec_servers_outstanding(net);
482		_leave(" [requeue]");
483	} else if (set_timer) {
484		if (timer_reduce(&net->fs_probe_timer, timer_at))
485			afs_dec_servers_outstanding(net);
486		_leave(" [timer]");
487	} else {
488		afs_dec_servers_outstanding(net);
489		_leave(" [quiesce]");
490	}
491}
492
493/*
494 * Wait for a probe on a particular fileserver to complete for 2s.
495 */
496int afs_wait_for_one_fs_probe(struct afs_server *server, struct afs_endpoint_state *estate,
497			      unsigned long exclude, bool is_intr)
498{
499	struct wait_queue_entry wait;
500	unsigned long timo = 2 * HZ;
501
502	if (atomic_read(&estate->nr_probing) == 0)
503		goto dont_wait;
504
505	init_wait_entry(&wait, 0);
506	for (;;) {
507		prepare_to_wait_event(&server->probe_wq, &wait,
508				      is_intr ? TASK_INTERRUPTIBLE : TASK_UNINTERRUPTIBLE);
509		if (timo == 0 ||
510		    test_bit(AFS_ESTATE_SUPERSEDED, &estate->flags) ||
511		    (estate->responsive_set & ~exclude) ||
512		    atomic_read(&estate->nr_probing) == 0 ||
513		    (is_intr && signal_pending(current)))
514			break;
515		timo = schedule_timeout(timo);
516	}
517
518	finish_wait(&server->probe_wq, &wait);
519
520dont_wait:
521	if (test_bit(AFS_ESTATE_SUPERSEDED, &estate->flags))
522		return 0;
523	if (estate->responsive_set & ~exclude)
524		return 1;
525	if (is_intr && signal_pending(current))
526		return -ERESTARTSYS;
527	if (timo == 0)
528		return -ETIME;
529	return -EDESTADDRREQ;
530}
531
532/*
533 * Clean up the probing when the namespace is killed off.
534 */
535void afs_fs_probe_cleanup(struct afs_net *net)
536{
537	if (timer_delete_sync(&net->fs_probe_timer))
538		afs_dec_servers_outstanding(net);
539}