1// SPDX-License-Identifier: GPL-2.0-or-later
2/* AFS vlserver 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
14
15/*
16 * Handle the completion of a set of probes.
17 */
18static void afs_finished_vl_probe(struct afs_vlserver *server)
19{
20	if (!(server->probe.flags & AFS_VLSERVER_PROBE_RESPONDED)) {
21		server->rtt = UINT_MAX;
22		clear_bit(AFS_VLSERVER_FL_RESPONDING, &server->flags);
23	}
24
25	clear_bit_unlock(AFS_VLSERVER_FL_PROBING, &server->flags);
26	wake_up_bit(&server->flags, AFS_VLSERVER_FL_PROBING);
27}
28
29/*
30 * Handle the completion of a probe RPC call.
31 */
32static void afs_done_one_vl_probe(struct afs_vlserver *server, bool wake_up)
33{
34	if (atomic_dec_and_test(&server->probe_outstanding)) {
35		afs_finished_vl_probe(server);
36		wake_up = true;
37	}
38
39	if (wake_up)
40		wake_up_all(&server->probe_wq);
41}
42
43/*
44 * Process the result of probing a vlserver.  This is called after successful
45 * or failed delivery of an VL.GetCapabilities operation.
46 */
47void afs_vlserver_probe_result(struct afs_call *call)
48{
49	struct afs_addr_list *alist = call->vl_probe;
50	struct afs_vlserver *server = call->vlserver;
51	struct afs_address *addr = &alist->addrs[call->probe_index];
52	unsigned int server_index = call->server_index;
53	unsigned int rtt_us = 0;
54	unsigned int index = call->probe_index;
55	bool have_result = false;
56	int ret = call->error;
57
58	_enter("%s,%u,%u,%d,%d", server->name, server_index, index, ret, call->abort_code);
59
60	spin_lock(&server->probe_lock);
61
62	switch (ret) {
63	case 0:
64		server->probe.error = 0;
65		goto responded;
66	case -ECONNABORTED:
67		if (!(server->probe.flags & AFS_VLSERVER_PROBE_RESPONDED)) {
68			server->probe.abort_code = call->abort_code;
69			server->probe.error = ret;
70		}
71		goto responded;
72	case -ENOMEM:
73	case -ENONET:
74	case -EKEYEXPIRED:
75	case -EKEYREVOKED:
76	case -EKEYREJECTED:
77		server->probe.flags |= AFS_VLSERVER_PROBE_LOCAL_FAILURE;
78		if (server->probe.error == 0)
79			server->probe.error = ret;
80		trace_afs_io_error(call->debug_id, ret, afs_io_error_vl_probe_fail);
81		goto out;
82	case -ECONNRESET: /* Responded, but call expired. */
83	case -ERFKILL:
84	case -EADDRNOTAVAIL:
85	case -ENETUNREACH:
86	case -EHOSTUNREACH:
87	case -EHOSTDOWN:
88	case -ECONNREFUSED:
89	case -ETIMEDOUT:
90	case -ETIME:
91	default:
92		clear_bit(index, &alist->responded);
93		set_bit(index, &alist->probe_failed);
94		if (!(server->probe.flags & AFS_VLSERVER_PROBE_RESPONDED) &&
95		    (server->probe.error == 0 ||
96		     server->probe.error == -ETIMEDOUT ||
97		     server->probe.error == -ETIME))
98			server->probe.error = ret;
99		trace_afs_io_error(call->debug_id, ret, afs_io_error_vl_probe_fail);
100		goto out;
101	}
102
103responded:
104	set_bit(index, &alist->responded);
105	clear_bit(index, &alist->probe_failed);
106
107	if (call->service_id == YFS_VL_SERVICE) {
108		server->probe.flags |= AFS_VLSERVER_PROBE_IS_YFS;
109		set_bit(AFS_VLSERVER_FL_IS_YFS, &server->flags);
110		server->service_id = call->service_id;
111	} else {
112		server->probe.flags |= AFS_VLSERVER_PROBE_NOT_YFS;
113		if (!(server->probe.flags & AFS_VLSERVER_PROBE_IS_YFS)) {
114			clear_bit(AFS_VLSERVER_FL_IS_YFS, &server->flags);
115			server->service_id = call->service_id;
116		}
117	}
118
119	rtt_us = rxrpc_kernel_get_srtt(addr->peer);
120	if (rtt_us < server->probe.rtt) {
121		server->probe.rtt = rtt_us;
122		server->rtt = rtt_us;
123		alist->preferred = index;
124	}
125
126	smp_wmb(); /* Set rtt before responded. */
127	server->probe.flags |= AFS_VLSERVER_PROBE_RESPONDED;
128	set_bit(AFS_VLSERVER_FL_PROBED, &server->flags);
129	set_bit(AFS_VLSERVER_FL_RESPONDING, &server->flags);
130	have_result = true;
131out:
132	spin_unlock(&server->probe_lock);
133
134	trace_afs_vl_probe(server, false, alist, index, call->error, call->abort_code, rtt_us);
135	_debug("probe [%u][%u] %pISpc rtt=%d ret=%d",
136	       server_index, index, rxrpc_kernel_remote_addr(addr->peer),
137	       rtt_us, ret);
138
139	afs_done_one_vl_probe(server, have_result);
140}
141
142/*
143 * Probe all of a vlserver's addresses to find out the best route and to
144 * query its capabilities.
145 */
146static bool afs_do_probe_vlserver(struct afs_net *net,
147				  struct afs_vlserver *server,
148				  struct key *key,
149				  unsigned int server_index,
150				  struct afs_error *_e)
151{
152	struct afs_addr_list *alist;
153	struct afs_call *call;
154	unsigned long unprobed;
155	unsigned int index, i;
156	bool in_progress = false;
157	int best_prio;
158
159	_enter("%s", server->name);
160
161	read_lock(&server->lock);
162	alist = rcu_dereference_protected(server->addresses,
163					  lockdep_is_held(&server->lock));
164	afs_get_addrlist(alist, afs_alist_trace_get_vlprobe);
165	read_unlock(&server->lock);
166
167	atomic_set(&server->probe_outstanding, alist->nr_addrs);
168	memset(&server->probe, 0, sizeof(server->probe));
169	server->probe.rtt = UINT_MAX;
170
171	unprobed = (1UL << alist->nr_addrs) - 1;
172	while (unprobed) {
173		best_prio = -1;
174		index = 0;
175		for (i = 0; i < alist->nr_addrs; i++) {
176			if (test_bit(i, &unprobed) &&
177			    alist->addrs[i].prio > best_prio) {
178				index = i;
179				best_prio = alist->addrs[i].prio;
180			}
181		}
182		__clear_bit(index, &unprobed);
183
184		trace_afs_vl_probe(server, true, alist, index, 0, 0, 0);
185		call = afs_vl_get_capabilities(net, alist, index, key, server,
186					       server_index);
187		if (!IS_ERR(call)) {
188			afs_prioritise_error(_e, call->error, call->abort_code);
189			afs_put_call(call);
190			in_progress = true;
191		} else {
192			afs_prioritise_error(_e, PTR_ERR(call), 0);
193			afs_done_one_vl_probe(server, false);
194		}
195	}
196
197	afs_put_addrlist(alist, afs_alist_trace_put_vlprobe);
198	return in_progress;
199}
200
201/*
202 * Send off probes to all unprobed servers.
203 */
204int afs_send_vl_probes(struct afs_net *net, struct key *key,
205		       struct afs_vlserver_list *vllist)
206{
207	struct afs_vlserver *server;
208	struct afs_error e = {};
209	bool in_progress = false;
210	int i;
211
212	for (i = 0; i < vllist->nr_servers; i++) {
213		server = vllist->servers[i].server;
214		if (test_bit(AFS_VLSERVER_FL_PROBED, &server->flags))
215			continue;
216
217		if (!test_and_set_bit_lock(AFS_VLSERVER_FL_PROBING, &server->flags) &&
218		    afs_do_probe_vlserver(net, server, key, i, &e))
219			in_progress = true;
220	}
221
222	return in_progress ? 0 : e.error;
223}
224
225/*
226 * Wait for the first as-yet untried server to respond.
227 */
228int afs_wait_for_vl_probes(struct afs_vlserver_list *vllist,
229			   unsigned long untried)
230{
231	struct wait_queue_entry *waits;
232	struct afs_vlserver *server;
233	unsigned int rtt = UINT_MAX, rtt_s;
234	bool have_responders = false;
235	int pref = -1, i;
236
237	_enter("%u,%lx", vllist->nr_servers, untried);
238
239	/* Only wait for servers that have a probe outstanding. */
240	for (i = 0; i < vllist->nr_servers; i++) {
241		if (test_bit(i, &untried)) {
242			server = vllist->servers[i].server;
243			if (!test_bit(AFS_VLSERVER_FL_PROBING, &server->flags))
244				__clear_bit(i, &untried);
245			if (server->probe.flags & AFS_VLSERVER_PROBE_RESPONDED)
246				have_responders = true;
247		}
248	}
249	if (have_responders || !untried)
250		return 0;
251
252	waits = kmalloc(array_size(vllist->nr_servers, sizeof(*waits)), GFP_KERNEL);
253	if (!waits)
254		return -ENOMEM;
255
256	for (i = 0; i < vllist->nr_servers; i++) {
257		if (test_bit(i, &untried)) {
258			server = vllist->servers[i].server;
259			init_waitqueue_entry(&waits[i], current);
260			add_wait_queue(&server->probe_wq, &waits[i]);
261		}
262	}
263
264	for (;;) {
265		bool still_probing = false;
266
267		set_current_state(TASK_INTERRUPTIBLE);
268		for (i = 0; i < vllist->nr_servers; i++) {
269			if (test_bit(i, &untried)) {
270				server = vllist->servers[i].server;
271				if (server->probe.flags & AFS_VLSERVER_PROBE_RESPONDED)
272					goto stop;
273				if (test_bit(AFS_VLSERVER_FL_PROBING, &server->flags))
274					still_probing = true;
275			}
276		}
277
278		if (!still_probing || signal_pending(current))
279			goto stop;
280		schedule();
281	}
282
283stop:
284	set_current_state(TASK_RUNNING);
285
286	for (i = 0; i < vllist->nr_servers; i++) {
287		if (test_bit(i, &untried)) {
288			server = vllist->servers[i].server;
289			rtt_s = READ_ONCE(server->rtt);
290			if (test_bit(AFS_VLSERVER_FL_RESPONDING, &server->flags) &&
291			    rtt_s < rtt) {
292				pref = i;
293				rtt = rtt_s;
294			}
295
296			remove_wait_queue(&server->probe_wq, &waits[i]);
297		}
298	}
299
300	kfree(waits);
301
302	if (pref == -1 && signal_pending(current))
303		return -ERESTARTSYS;
304
305	if (pref >= 0)
306		vllist->preferred = pref;
307
308	_leave(" = 0 [%u]", pref);
309	return 0;
310}
311