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
afs_vl_probe_done(struct afs_vlserver * server)14 static bool afs_vl_probe_done(struct afs_vlserver *server)
15 {
16 if (!atomic_dec_and_test(&server->probe_outstanding))
17 return false;
18
19 wake_up_var(&server->probe_outstanding);
20 clear_bit_unlock(AFS_VLSERVER_FL_PROBING, &server->flags);
21 wake_up_bit(&server->flags, AFS_VLSERVER_FL_PROBING);
22 return true;
23 }
24
25 /*
26 * Process the result of probing a vlserver. This is called after successful
27 * or failed delivery of an VL.GetCapabilities operation.
28 */
afs_vlserver_probe_result(struct afs_call * call)29 void afs_vlserver_probe_result(struct afs_call *call)
30 {
31 struct afs_addr_list *alist = call->alist;
32 struct afs_vlserver *server = call->vlserver;
33 unsigned int server_index = call->server_index;
34 unsigned int index = call->addr_ix;
35 unsigned int rtt = UINT_MAX;
36 bool have_result = false;
37 u64 _rtt;
38 int ret = call->error;
39
40 _enter("%s,%u,%u,%d,%d", server->name, server_index, index, ret, call->abort_code);
41
42 spin_lock(&server->probe_lock);
43
44 switch (ret) {
45 case 0:
46 server->probe.error = 0;
47 goto responded;
48 case -ECONNABORTED:
49 if (!server->probe.responded) {
50 server->probe.abort_code = call->abort_code;
51 server->probe.error = ret;
52 }
53 goto responded;
54 case -ENOMEM:
55 case -ENONET:
56 server->probe.local_failure = true;
57 afs_io_error(call, afs_io_error_vl_probe_fail);
58 goto out;
59 case -ECONNRESET: /* Responded, but call expired. */
60 case -ERFKILL:
61 case -EADDRNOTAVAIL:
62 case -ENETUNREACH:
63 case -EHOSTUNREACH:
64 case -EHOSTDOWN:
65 case -ECONNREFUSED:
66 case -ETIMEDOUT:
67 case -ETIME:
68 default:
69 clear_bit(index, &alist->responded);
70 set_bit(index, &alist->failed);
71 if (!server->probe.responded &&
72 (server->probe.error == 0 ||
73 server->probe.error == -ETIMEDOUT ||
74 server->probe.error == -ETIME))
75 server->probe.error = ret;
76 afs_io_error(call, afs_io_error_vl_probe_fail);
77 goto out;
78 }
79
80 responded:
81 set_bit(index, &alist->responded);
82 clear_bit(index, &alist->failed);
83
84 if (call->service_id == YFS_VL_SERVICE) {
85 server->probe.is_yfs = true;
86 set_bit(AFS_VLSERVER_FL_IS_YFS, &server->flags);
87 alist->addrs[index].srx_service = call->service_id;
88 } else {
89 server->probe.not_yfs = true;
90 if (!server->probe.is_yfs) {
91 clear_bit(AFS_VLSERVER_FL_IS_YFS, &server->flags);
92 alist->addrs[index].srx_service = call->service_id;
93 }
94 }
95
96 /* Get the RTT and scale it to fit into a 32-bit value that represents
97 * over a minute of time so that we can access it with one instruction
98 * on a 32-bit system.
99 */
100 _rtt = rxrpc_kernel_get_rtt(call->net->socket, call->rxcall);
101 _rtt /= 64;
102 rtt = (_rtt > UINT_MAX) ? UINT_MAX : _rtt;
103 if (rtt < server->probe.rtt) {
104 server->probe.rtt = rtt;
105 alist->preferred = index;
106 have_result = true;
107 }
108
109 smp_wmb(); /* Set rtt before responded. */
110 server->probe.responded = true;
111 set_bit(AFS_VLSERVER_FL_PROBED, &server->flags);
112 out:
113 spin_unlock(&server->probe_lock);
114
115 _debug("probe [%u][%u] %pISpc rtt=%u ret=%d",
116 server_index, index, &alist->addrs[index].transport,
117 (unsigned int)rtt, ret);
118
119 have_result |= afs_vl_probe_done(server);
120 if (have_result) {
121 server->probe.have_result = true;
122 wake_up_var(&server->probe.have_result);
123 wake_up_all(&server->probe_wq);
124 }
125 }
126
127 /*
128 * Probe all of a vlserver's addresses to find out the best route and to
129 * query its capabilities.
130 */
afs_do_probe_vlserver(struct afs_net * net,struct afs_vlserver * server,struct key * key,unsigned int server_index,struct afs_error * _e)131 static bool afs_do_probe_vlserver(struct afs_net *net,
132 struct afs_vlserver *server,
133 struct key *key,
134 unsigned int server_index,
135 struct afs_error *_e)
136 {
137 struct afs_addr_cursor ac = {
138 .index = 0,
139 };
140 struct afs_call *call;
141 bool in_progress = false;
142
143 _enter("%s", server->name);
144
145 read_lock(&server->lock);
146 ac.alist = rcu_dereference_protected(server->addresses,
147 lockdep_is_held(&server->lock));
148 read_unlock(&server->lock);
149
150 atomic_set(&server->probe_outstanding, ac.alist->nr_addrs);
151 memset(&server->probe, 0, sizeof(server->probe));
152 server->probe.rtt = UINT_MAX;
153
154 for (ac.index = 0; ac.index < ac.alist->nr_addrs; ac.index++) {
155 call = afs_vl_get_capabilities(net, &ac, key, server,
156 server_index);
157 if (!IS_ERR(call)) {
158 afs_put_call(call);
159 in_progress = true;
160 } else {
161 afs_prioritise_error(_e, PTR_ERR(call), ac.abort_code);
162 }
163 }
164
165 if (!in_progress)
166 afs_vl_probe_done(server);
167 return in_progress;
168 }
169
170 /*
171 * Send off probes to all unprobed servers.
172 */
afs_send_vl_probes(struct afs_net * net,struct key * key,struct afs_vlserver_list * vllist)173 int afs_send_vl_probes(struct afs_net *net, struct key *key,
174 struct afs_vlserver_list *vllist)
175 {
176 struct afs_vlserver *server;
177 struct afs_error e;
178 bool in_progress = false;
179 int i;
180
181 e.error = 0;
182 e.responded = false;
183 for (i = 0; i < vllist->nr_servers; i++) {
184 server = vllist->servers[i].server;
185 if (test_bit(AFS_VLSERVER_FL_PROBED, &server->flags))
186 continue;
187
188 if (!test_and_set_bit_lock(AFS_VLSERVER_FL_PROBING, &server->flags) &&
189 afs_do_probe_vlserver(net, server, key, i, &e))
190 in_progress = true;
191 }
192
193 return in_progress ? 0 : e.error;
194 }
195
196 /*
197 * Wait for the first as-yet untried server to respond.
198 */
afs_wait_for_vl_probes(struct afs_vlserver_list * vllist,unsigned long untried)199 int afs_wait_for_vl_probes(struct afs_vlserver_list *vllist,
200 unsigned long untried)
201 {
202 struct wait_queue_entry *waits;
203 struct afs_vlserver *server;
204 unsigned int rtt = UINT_MAX;
205 bool have_responders = false;
206 int pref = -1, i;
207
208 _enter("%u,%lx", vllist->nr_servers, untried);
209
210 /* Only wait for servers that have a probe outstanding. */
211 for (i = 0; i < vllist->nr_servers; i++) {
212 if (test_bit(i, &untried)) {
213 server = vllist->servers[i].server;
214 if (!test_bit(AFS_VLSERVER_FL_PROBING, &server->flags))
215 __clear_bit(i, &untried);
216 if (server->probe.responded)
217 have_responders = true;
218 }
219 }
220 if (have_responders || !untried)
221 return 0;
222
223 waits = kmalloc(array_size(vllist->nr_servers, sizeof(*waits)), GFP_KERNEL);
224 if (!waits)
225 return -ENOMEM;
226
227 for (i = 0; i < vllist->nr_servers; i++) {
228 if (test_bit(i, &untried)) {
229 server = vllist->servers[i].server;
230 init_waitqueue_entry(&waits[i], current);
231 add_wait_queue(&server->probe_wq, &waits[i]);
232 }
233 }
234
235 for (;;) {
236 bool still_probing = false;
237
238 set_current_state(TASK_INTERRUPTIBLE);
239 for (i = 0; i < vllist->nr_servers; i++) {
240 if (test_bit(i, &untried)) {
241 server = vllist->servers[i].server;
242 if (server->probe.responded)
243 goto stop;
244 if (test_bit(AFS_VLSERVER_FL_PROBING, &server->flags))
245 still_probing = true;
246 }
247 }
248
249 if (!still_probing || signal_pending(current))
250 goto stop;
251 schedule();
252 }
253
254 stop:
255 set_current_state(TASK_RUNNING);
256
257 for (i = 0; i < vllist->nr_servers; i++) {
258 if (test_bit(i, &untried)) {
259 server = vllist->servers[i].server;
260 if (server->probe.responded &&
261 server->probe.rtt < rtt) {
262 pref = i;
263 rtt = server->probe.rtt;
264 }
265
266 remove_wait_queue(&server->probe_wq, &waits[i]);
267 }
268 }
269
270 kfree(waits);
271
272 if (pref == -1 && signal_pending(current))
273 return -ERESTARTSYS;
274
275 if (pref >= 0)
276 vllist->preferred = pref;
277
278 _leave(" = 0 [%u]", pref);
279 return 0;
280 }
281
