summaryrefslogtreecommitdiffstats
path: root/fs/afs/vl_probe.c
blob: c0f616bd70cba33f292e7c7cbb9d3c4e3e310f21 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
/* AFS vlserver probing
 *
 * Copyright (C) 2018 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public Licence
 * as published by the Free Software Foundation; either version
 * 2 of the Licence, or (at your option) any later version.
 */

#include <linux/sched.h>
#include <linux/slab.h>
#include "afs_fs.h"
#include "internal.h"
#include "protocol_yfs.h"

static bool afs_vl_probe_done(struct afs_vlserver *server)
{
	if (!atomic_dec_and_test(&server->probe_outstanding))
		return false;

	wake_up_var(&server->probe_outstanding);
	clear_bit_unlock(AFS_VLSERVER_FL_PROBING, &server->flags);
	wake_up_bit(&server->flags, AFS_VLSERVER_FL_PROBING);
	return true;
}

/*
 * Process the result of probing a vlserver.  This is called after successful
 * or failed delivery of an VL.GetCapabilities operation.
 */
void afs_vlserver_probe_result(struct afs_call *call)
{
	struct afs_addr_list *alist = call->alist;
	struct afs_vlserver *server = call->reply[0];
	unsigned int server_index = (long)call->reply[1];
	unsigned int index = call->addr_ix;
	unsigned int rtt = UINT_MAX;
	bool have_result = false;
	u64 _rtt;
	int ret = call->error;

	_enter("%s,%u,%u,%d,%d", server->name, server_index, index, ret, call->abort_code);

	spin_lock(&server->probe_lock);

	switch (ret) {
	case 0:
		server->probe.error = 0;
		goto responded;
	case -ECONNABORTED:
		if (!server->probe.responded) {
			server->probe.abort_code = call->abort_code;
			server->probe.error = ret;
		}
		goto responded;
	case -ENOMEM:
	case -ENONET:
		server->probe.local_failure = true;
		afs_io_error(call, afs_io_error_vl_probe_fail);
		goto out;
	case -ECONNRESET: /* Responded, but call expired. */
	case -ENETUNREACH:
	case -EHOSTUNREACH:
	case -ECONNREFUSED:
	case -ETIMEDOUT:
	case -ETIME:
	default:
		clear_bit(index, &alist->responded);
		set_bit(index, &alist->failed);
		if (!server->probe.responded &&
		    (server->probe.error == 0 ||
		     server->probe.error == -ETIMEDOUT ||
		     server->probe.error == -ETIME))
			server->probe.error = ret;
		afs_io_error(call, afs_io_error_vl_probe_fail);
		goto out;
	}

responded:
	set_bit(index, &alist->responded);
	clear_bit(index, &alist->failed);

	if (call->service_id == YFS_VL_SERVICE) {
		server->probe.is_yfs = true;
		set_bit(AFS_VLSERVER_FL_IS_YFS, &server->flags);
		alist->addrs[index].srx_service = call->service_id;
	} else {
		server->probe.not_yfs = true;
		if (!server->probe.is_yfs) {
			clear_bit(AFS_VLSERVER_FL_IS_YFS, &server->flags);
			alist->addrs[index].srx_service = call->service_id;
		}
	}

	/* Get the RTT and scale it to fit into a 32-bit value that represents
	 * over a minute of time so that we can access it with one instruction
	 * on a 32-bit system.
	 */
	_rtt = rxrpc_kernel_get_rtt(call->net->socket, call->rxcall);
	_rtt /= 64;
	rtt = (_rtt > UINT_MAX) ? UINT_MAX : _rtt;
	if (rtt < server->probe.rtt) {
		server->probe.rtt = rtt;
		alist->preferred = index;
		have_result = true;
	}

	smp_wmb(); /* Set rtt before responded. */
	server->probe.responded = true;
	set_bit(AFS_VLSERVER_FL_PROBED, &server->flags);
out:
	spin_unlock(&server->probe_lock);

	_debug("probe [%u][%u] %pISpc rtt=%u ret=%d",
	       server_index, index, &alist->addrs[index].transport,
	       (unsigned int)rtt, ret);

	have_result |= afs_vl_probe_done(server);
	if (have_result) {
		server->probe.have_result = true;
		wake_up_var(&server->probe.have_result);
		wake_up_all(&server->probe_wq);
	}
}

/*
 * Probe all of a vlserver's addresses to find out the best route and to
 * query its capabilities.
 */
static int afs_do_probe_vlserver(struct afs_net *net,
				 struct afs_vlserver *server,
				 struct key *key,
				 unsigned int server_index)
{
	struct afs_addr_cursor ac = {
		.index = 0,
	};
	int ret;

	_enter("%s", server->name);

	read_lock(&server->lock);
	ac.alist = rcu_dereference_protected(server->addresses,
					     lockdep_is_held(&server->lock));
	read_unlock(&server->lock);

	atomic_set(&server->probe_outstanding, ac.alist->nr_addrs);
	memset(&server->probe, 0, sizeof(server->probe));
	server->probe.rtt = UINT_MAX;

	for (ac.index = 0; ac.index < ac.alist->nr_addrs; ac.index++) {
		ret = afs_vl_get_capabilities(net, &ac, key, server,
					      server_index, true);
		if (ret != -EINPROGRESS) {
			afs_vl_probe_done(server);
			return ret;
		}
	}

	return 0;
}

/*
 * Send off probes to all unprobed servers.
 */
int afs_send_vl_probes(struct afs_net *net, struct key *key,
		       struct afs_vlserver_list *vllist)
{
	struct afs_vlserver *server;
	int i, ret;

	for (i = 0; i < vllist->nr_servers; i++) {
		server = vllist->servers[i].server;
		if (test_bit(AFS_VLSERVER_FL_PROBED, &server->flags))
			continue;

		if (!test_and_set_bit_lock(AFS_VLSERVER_FL_PROBING, &server->flags)) {
			ret = afs_do_probe_vlserver(net, server, key, i);
			if (ret)
				return ret;
		}
	}

	return 0;
}

/*
 * Wait for the first as-yet untried server to respond.
 */
int afs_wait_for_vl_probes(struct afs_vlserver_list *vllist,
			   unsigned long untried)
{
	struct wait_queue_entry *waits;
	struct afs_vlserver *server;
	unsigned int rtt = UINT_MAX;
	bool have_responders = false;
	int pref = -1, i;

	_enter("%u,%lx", vllist->nr_servers, untried);

	/* Only wait for servers that have a probe outstanding. */
	for (i = 0; i < vllist->nr_servers; i++) {
		if (test_bit(i, &untried)) {
			server = vllist->servers[i].server;
			if (!test_bit(AFS_VLSERVER_FL_PROBING, &server->flags))
				__clear_bit(i, &untried);
			if (server->probe.responded)
				have_responders = true;
		}
	}
	if (have_responders || !untried)
		return 0;

	waits = kmalloc(array_size(vllist->nr_servers, sizeof(*waits)), GFP_KERNEL);
	if (!waits)
		return -ENOMEM;

	for (i = 0; i < vllist->nr_servers; i++) {
		if (test_bit(i, &untried)) {
			server = vllist->servers[i].server;
			init_waitqueue_entry(&waits[i], current);
			add_wait_queue(&server->probe_wq, &waits[i]);
		}
	}

	for (;;) {
		bool still_probing = false;

		set_current_state(TASK_INTERRUPTIBLE);
		for (i = 0; i < vllist->nr_servers; i++) {
			if (test_bit(i, &untried)) {
				server = vllist->servers[i].server;
				if (server->probe.responded)
					goto stop;
				if (test_bit(AFS_VLSERVER_FL_PROBING, &server->flags))
					still_probing = true;
			}
		}

		if (!still_probing || unlikely(signal_pending(current)))
			goto stop;
		schedule();
	}

stop:
	set_current_state(TASK_RUNNING);

	for (i = 0; i < vllist->nr_servers; i++) {
		if (test_bit(i, &untried)) {
			server = vllist->servers[i].server;
			if (server->probe.responded &&
			    server->probe.rtt < rtt) {
				pref = i;
				rtt = server->probe.rtt;
			}

			remove_wait_queue(&server->probe_wq, &waits[i]);
		}
	}

	kfree(waits);

	if (pref == -1 && signal_pending(current))
		return -ERESTARTSYS;

	if (pref >= 0)
		vllist->preferred = pref;

	_leave(" = 0 [%u]", pref);
	return 0;
}
OpenPOWER on IntegriCloud