Merge tag 'for-5.2/dm-changes-v2' of git://git.kernel.org/pub/scm/linux/kernel/git...
[linux-2.6-microblaze.git] / fs / afs / fs_probe.c
1 /* AFS fileserver probing
2  *
3  * Copyright (C) 2018 Red Hat, Inc. All Rights Reserved.
4  * Written by David Howells (dhowells@redhat.com)
5  *
6  * This program is free software; you can redistribute it and/or
7  * modify it under the terms of the GNU General Public Licence
8  * as published by the Free Software Foundation; either version
9  * 2 of the Licence, or (at your option) any later version.
10  */
11
12 #include <linux/sched.h>
13 #include <linux/slab.h>
14 #include "afs_fs.h"
15 #include "internal.h"
16 #include "protocol_yfs.h"
17
18 static bool afs_fs_probe_done(struct afs_server *server)
19 {
20         if (!atomic_dec_and_test(&server->probe_outstanding))
21                 return false;
22
23         wake_up_var(&server->probe_outstanding);
24         clear_bit_unlock(AFS_SERVER_FL_PROBING, &server->flags);
25         wake_up_bit(&server->flags, AFS_SERVER_FL_PROBING);
26         return true;
27 }
28
29 /*
30  * Process the result of probing a fileserver.  This is called after successful
31  * or failed delivery of an FS.GetCapabilities operation.
32  */
33 void afs_fileserver_probe_result(struct afs_call *call)
34 {
35         struct afs_addr_list *alist = call->alist;
36         struct afs_server *server = call->reply[0];
37         unsigned int server_index = (long)call->reply[1];
38         unsigned int index = call->addr_ix;
39         unsigned int rtt = UINT_MAX;
40         bool have_result = false;
41         u64 _rtt;
42         int ret = call->error;
43
44         _enter("%pU,%u", &server->uuid, index);
45
46         spin_lock(&server->probe_lock);
47
48         switch (ret) {
49         case 0:
50                 server->probe.error = 0;
51                 goto responded;
52         case -ECONNABORTED:
53                 if (!server->probe.responded) {
54                         server->probe.abort_code = call->abort_code;
55                         server->probe.error = ret;
56                 }
57                 goto responded;
58         case -ENOMEM:
59         case -ENONET:
60                 server->probe.local_failure = true;
61                 afs_io_error(call, afs_io_error_fs_probe_fail);
62                 goto out;
63         case -ECONNRESET: /* Responded, but call expired. */
64         case -ERFKILL:
65         case -EADDRNOTAVAIL:
66         case -ENETUNREACH:
67         case -EHOSTUNREACH:
68         case -EHOSTDOWN:
69         case -ECONNREFUSED:
70         case -ETIMEDOUT:
71         case -ETIME:
72         default:
73                 clear_bit(index, &alist->responded);
74                 set_bit(index, &alist->failed);
75                 if (!server->probe.responded &&
76                     (server->probe.error == 0 ||
77                      server->probe.error == -ETIMEDOUT ||
78                      server->probe.error == -ETIME))
79                         server->probe.error = ret;
80                 afs_io_error(call, afs_io_error_fs_probe_fail);
81                 goto out;
82         }
83
84 responded:
85         set_bit(index, &alist->responded);
86         clear_bit(index, &alist->failed);
87
88         if (call->service_id == YFS_FS_SERVICE) {
89                 server->probe.is_yfs = true;
90                 set_bit(AFS_SERVER_FL_IS_YFS, &server->flags);
91                 alist->addrs[index].srx_service = call->service_id;
92         } else {
93                 server->probe.not_yfs = true;
94                 if (!server->probe.is_yfs) {
95                         clear_bit(AFS_SERVER_FL_IS_YFS, &server->flags);
96                         alist->addrs[index].srx_service = call->service_id;
97                 }
98         }
99
100         /* Get the RTT and scale it to fit into a 32-bit value that represents
101          * over a minute of time so that we can access it with one instruction
102          * on a 32-bit system.
103          */
104         _rtt = rxrpc_kernel_get_rtt(call->net->socket, call->rxcall);
105         _rtt /= 64;
106         rtt = (_rtt > UINT_MAX) ? UINT_MAX : _rtt;
107         if (rtt < server->probe.rtt) {
108                 server->probe.rtt = rtt;
109                 alist->preferred = index;
110                 have_result = true;
111         }
112
113         smp_wmb(); /* Set rtt before responded. */
114         server->probe.responded = true;
115         set_bit(AFS_SERVER_FL_PROBED, &server->flags);
116 out:
117         spin_unlock(&server->probe_lock);
118
119         _debug("probe [%u][%u] %pISpc rtt=%u ret=%d",
120                server_index, index, &alist->addrs[index].transport,
121                (unsigned int)rtt, ret);
122
123         have_result |= afs_fs_probe_done(server);
124         if (have_result) {
125                 server->probe.have_result = true;
126                 wake_up_var(&server->probe.have_result);
127                 wake_up_all(&server->probe_wq);
128         }
129 }
130
131 /*
132  * Probe all of a fileserver's addresses to find out the best route and to
133  * query its capabilities.
134  */
135 static int afs_do_probe_fileserver(struct afs_net *net,
136                                    struct afs_server *server,
137                                    struct key *key,
138                                    unsigned int server_index,
139                                    struct afs_error *_e)
140 {
141         struct afs_addr_cursor ac = {
142                 .index = 0,
143         };
144         struct afs_call *call;
145         bool in_progress = false;
146
147         _enter("%pU", &server->uuid);
148
149         read_lock(&server->fs_lock);
150         ac.alist = rcu_dereference_protected(server->addresses,
151                                              lockdep_is_held(&server->fs_lock));
152         read_unlock(&server->fs_lock);
153
154         atomic_set(&server->probe_outstanding, ac.alist->nr_addrs);
155         memset(&server->probe, 0, sizeof(server->probe));
156         server->probe.rtt = UINT_MAX;
157
158         for (ac.index = 0; ac.index < ac.alist->nr_addrs; ac.index++) {
159                 call = afs_fs_get_capabilities(net, server, &ac, key, server_index);
160                 if (!IS_ERR(call)) {
161                         afs_put_call(call);
162                         in_progress = true;
163                 } else {
164                         afs_prioritise_error(_e, PTR_ERR(call), ac.abort_code);
165                 }
166         }
167
168         if (!in_progress)
169                 afs_fs_probe_done(server);
170         return in_progress;
171 }
172
173 /*
174  * Send off probes to all unprobed servers.
175  */
176 int afs_probe_fileservers(struct afs_net *net, struct key *key,
177                           struct afs_server_list *list)
178 {
179         struct afs_server *server;
180         struct afs_error e;
181         bool in_progress = false;
182         int i;
183
184         e.error = 0;
185         e.responded = false;
186         for (i = 0; i < list->nr_servers; i++) {
187                 server = list->servers[i].server;
188                 if (test_bit(AFS_SERVER_FL_PROBED, &server->flags))
189                         continue;
190
191                 if (!test_and_set_bit_lock(AFS_SERVER_FL_PROBING, &server->flags) &&
192                     afs_do_probe_fileserver(net, server, key, i, &e))
193                         in_progress = true;
194         }
195
196         return in_progress ? 0 : e.error;
197 }
198
199 /*
200  * Wait for the first as-yet untried fileserver to respond.
201  */
202 int afs_wait_for_fs_probes(struct afs_server_list *slist, unsigned long untried)
203 {
204         struct wait_queue_entry *waits;
205         struct afs_server *server;
206         unsigned int rtt = UINT_MAX;
207         bool have_responders = false;
208         int pref = -1, i;
209
210         _enter("%u,%lx", slist->nr_servers, untried);
211
212         /* Only wait for servers that have a probe outstanding. */
213         for (i = 0; i < slist->nr_servers; i++) {
214                 if (test_bit(i, &untried)) {
215                         server = slist->servers[i].server;
216                         if (!test_bit(AFS_SERVER_FL_PROBING, &server->flags))
217                                 __clear_bit(i, &untried);
218                         if (server->probe.responded)
219                                 have_responders = true;
220                 }
221         }
222         if (have_responders || !untried)
223                 return 0;
224
225         waits = kmalloc(array_size(slist->nr_servers, sizeof(*waits)), GFP_KERNEL);
226         if (!waits)
227                 return -ENOMEM;
228
229         for (i = 0; i < slist->nr_servers; i++) {
230                 if (test_bit(i, &untried)) {
231                         server = slist->servers[i].server;
232                         init_waitqueue_entry(&waits[i], current);
233                         add_wait_queue(&server->probe_wq, &waits[i]);
234                 }
235         }
236
237         for (;;) {
238                 bool still_probing = false;
239
240                 set_current_state(TASK_INTERRUPTIBLE);
241                 for (i = 0; i < slist->nr_servers; i++) {
242                         if (test_bit(i, &untried)) {
243                                 server = slist->servers[i].server;
244                                 if (server->probe.responded)
245                                         goto stop;
246                                 if (test_bit(AFS_SERVER_FL_PROBING, &server->flags))
247                                         still_probing = true;
248                         }
249                 }
250
251                 if (!still_probing || signal_pending(current))
252                         goto stop;
253                 schedule();
254         }
255
256 stop:
257         set_current_state(TASK_RUNNING);
258
259         for (i = 0; i < slist->nr_servers; i++) {
260                 if (test_bit(i, &untried)) {
261                         server = slist->servers[i].server;
262                         if (server->probe.responded &&
263                             server->probe.rtt < rtt) {
264                                 pref = i;
265                                 rtt = server->probe.rtt;
266                         }
267
268                         remove_wait_queue(&server->probe_wq, &waits[i]);
269                 }
270         }
271
272         kfree(waits);
273
274         if (pref == -1 && signal_pending(current))
275                 return -ERESTARTSYS;
276
277         if (pref >= 0)
278                 slist->preferred = pref;
279         return 0;
280 }