1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* AFS fileserver 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_fs_probe_done(struct afs_server * server)14 static bool afs_fs_probe_done(struct afs_server *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_SERVER_FL_PROBING, &server->flags);
21 wake_up_bit(&server->flags, AFS_SERVER_FL_PROBING);
22 return true;
23 }
24
25 /*
26 * Process the result of probing a fileserver. This is called after successful
27 * or failed delivery of an FS.GetCapabilities operation.
28 */
afs_fileserver_probe_result(struct afs_call * call)29 void afs_fileserver_probe_result(struct afs_call *call)
30 {
31 struct afs_addr_list *alist = call->alist;
32 struct afs_server *server = call->server;
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("%pU,%u", &server->uuid, index);
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_fs_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_fs_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_FS_SERVICE) {
85 server->probe.is_yfs = true;
86 set_bit(AFS_SERVER_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_SERVER_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_SERVER_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_fs_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 fileserver's addresses to find out the best route and to
129 * query its capabilities.
130 */
afs_do_probe_fileserver(struct afs_net * net,struct afs_server * server,struct key * key,unsigned int server_index,struct afs_error * _e)131 static int afs_do_probe_fileserver(struct afs_net *net,
132 struct afs_server *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("%pU", &server->uuid);
144
145 read_lock(&server->fs_lock);
146 ac.alist = rcu_dereference_protected(server->addresses,
147 lockdep_is_held(&server->fs_lock));
148 read_unlock(&server->fs_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_fs_get_capabilities(net, server, &ac, key, server_index);
156 if (!IS_ERR(call)) {
157 afs_put_call(call);
158 in_progress = true;
159 } else {
160 afs_prioritise_error(_e, PTR_ERR(call), ac.abort_code);
161 }
162 }
163
164 if (!in_progress)
165 afs_fs_probe_done(server);
166 return in_progress;
167 }
168
169 /*
170 * Send off probes to all unprobed servers.
171 */
afs_probe_fileservers(struct afs_net * net,struct key * key,struct afs_server_list * list)172 int afs_probe_fileservers(struct afs_net *net, struct key *key,
173 struct afs_server_list *list)
174 {
175 struct afs_server *server;
176 struct afs_error e;
177 bool in_progress = false;
178 int i;
179
180 e.error = 0;
181 e.responded = false;
182 for (i = 0; i < list->nr_servers; i++) {
183 server = list->servers[i].server;
184 if (test_bit(AFS_SERVER_FL_PROBED, &server->flags))
185 continue;
186
187 if (!test_and_set_bit_lock(AFS_SERVER_FL_PROBING, &server->flags) &&
188 afs_do_probe_fileserver(net, server, key, i, &e))
189 in_progress = true;
190 }
191
192 return in_progress ? 0 : e.error;
193 }
194
195 /*
196 * Wait for the first as-yet untried fileserver to respond.
197 */
afs_wait_for_fs_probes(struct afs_server_list * slist,unsigned long untried)198 int afs_wait_for_fs_probes(struct afs_server_list *slist, unsigned long untried)
199 {
200 struct wait_queue_entry *waits;
201 struct afs_server *server;
202 unsigned int rtt = UINT_MAX;
203 bool have_responders = false;
204 int pref = -1, i;
205
206 _enter("%u,%lx", slist->nr_servers, untried);
207
208 /* Only wait for servers that have a probe outstanding. */
209 for (i = 0; i < slist->nr_servers; i++) {
210 if (test_bit(i, &untried)) {
211 server = slist->servers[i].server;
212 if (!test_bit(AFS_SERVER_FL_PROBING, &server->flags))
213 __clear_bit(i, &untried);
214 if (server->probe.responded)
215 have_responders = true;
216 }
217 }
218 if (have_responders || !untried)
219 return 0;
220
221 waits = kmalloc(array_size(slist->nr_servers, sizeof(*waits)), GFP_KERNEL);
222 if (!waits)
223 return -ENOMEM;
224
225 for (i = 0; i < slist->nr_servers; i++) {
226 if (test_bit(i, &untried)) {
227 server = slist->servers[i].server;
228 init_waitqueue_entry(&waits[i], current);
229 add_wait_queue(&server->probe_wq, &waits[i]);
230 }
231 }
232
233 for (;;) {
234 bool still_probing = false;
235
236 set_current_state(TASK_INTERRUPTIBLE);
237 for (i = 0; i < slist->nr_servers; i++) {
238 if (test_bit(i, &untried)) {
239 server = slist->servers[i].server;
240 if (server->probe.responded)
241 goto stop;
242 if (test_bit(AFS_SERVER_FL_PROBING, &server->flags))
243 still_probing = true;
244 }
245 }
246
247 if (!still_probing || signal_pending(current))
248 goto stop;
249 schedule();
250 }
251
252 stop:
253 set_current_state(TASK_RUNNING);
254
255 for (i = 0; i < slist->nr_servers; i++) {
256 if (test_bit(i, &untried)) {
257 server = slist->servers[i].server;
258 if (server->probe.responded &&
259 server->probe.rtt < rtt) {
260 pref = i;
261 rtt = server->probe.rtt;
262 }
263
264 remove_wait_queue(&server->probe_wq, &waits[i]);
265 }
266 }
267
268 kfree(waits);
269
270 if (pref == -1 && signal_pending(current))
271 return -ERESTARTSYS;
272
273 if (pref >= 0)
274 slist->preferred = pref;
275 return 0;
276 }
277