server.c 7.7 KB
Newer Older
D
David Howells 已提交
1
/* AFS server record management
L
Linus Torvalds 已提交
2
 *
3
 * Copyright (C) 2002, 2007 Red Hat, Inc. All Rights Reserved.
L
Linus Torvalds 已提交
4 5 6 7 8 9 10 11 12 13 14 15
 * 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 License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 */

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

16
unsigned afs_server_timeout = 10;	/* server timeout in seconds */
L
Linus Torvalds 已提交
17

18
static void afs_reap_server(struct work_struct *);
L
Linus Torvalds 已提交
19

20 21 22 23 24 25 26 27 28 29 30 31 32
/* tree of all the servers, indexed by IP address */
static struct rb_root afs_servers = RB_ROOT;
static DEFINE_RWLOCK(afs_servers_lock);

/* LRU list of all the servers not currently in use */
static LIST_HEAD(afs_server_graveyard);
static DEFINE_SPINLOCK(afs_server_graveyard_lock);
static DECLARE_DELAYED_WORK(afs_server_reaper, afs_reap_server);

/*
 * install a server record in the master tree
 */
static int afs_install_server(struct afs_server *server)
L
Linus Torvalds 已提交
33
{
34 35 36 37 38
	struct afs_server *xserver;
	struct rb_node **pp, *p;
	int ret;

	_enter("%p", server);
L
Linus Torvalds 已提交
39

40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55
	write_lock(&afs_servers_lock);

	ret = -EEXIST;
	pp = &afs_servers.rb_node;
	p = NULL;
	while (*pp) {
		p = *pp;
		_debug("- consider %p", p);
		xserver = rb_entry(p, struct afs_server, master_rb);
		if (server->addr.s_addr < xserver->addr.s_addr)
			pp = &(*pp)->rb_left;
		else if (server->addr.s_addr > xserver->addr.s_addr)
			pp = &(*pp)->rb_right;
		else
			goto error;
	}
L
Linus Torvalds 已提交
56

57 58 59
	rb_link_node(&server->master_rb, p, pp);
	rb_insert_color(&server->master_rb, &afs_servers);
	ret = 0;
L
Linus Torvalds 已提交
60

61 62 63 64
error:
	write_unlock(&afs_servers_lock);
	return ret;
}
L
Linus Torvalds 已提交
65 66

/*
67
 * allocate a new server record
L
Linus Torvalds 已提交
68
 */
69 70
static struct afs_server *afs_alloc_server(struct afs_cell *cell,
					   const struct in_addr *addr)
L
Linus Torvalds 已提交
71
{
72
	struct afs_server *server;
L
Linus Torvalds 已提交
73

74
	_enter("");
L
Linus Torvalds 已提交
75

76
	server = kzalloc(sizeof(struct afs_server), GFP_KERNEL);
77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93
	if (server) {
		atomic_set(&server->usage, 1);
		server->cell = cell;

		INIT_LIST_HEAD(&server->link);
		INIT_LIST_HEAD(&server->grave);
		init_rwsem(&server->sem);
		spin_lock_init(&server->fs_lock);
		server->fs_vnodes = RB_ROOT;
		server->cb_promises = RB_ROOT;
		spin_lock_init(&server->cb_lock);
		init_waitqueue_head(&server->cb_break_waitq);
		INIT_DELAYED_WORK(&server->cb_break_work,
				  afs_dispatch_give_up_callbacks);

		memcpy(&server->addr, addr, sizeof(struct in_addr));
		server->addr.s_addr = addr->s_addr;
L
Linus Torvalds 已提交
94 95
	}

96 97 98
	_leave(" = %p{%d}", server, atomic_read(&server->usage));
	return server;
}
L
Linus Torvalds 已提交
99

100 101 102 103 104 105 106
/*
 * get an FS-server record for a cell
 */
struct afs_server *afs_lookup_server(struct afs_cell *cell,
				     const struct in_addr *addr)
{
	struct afs_server *server, *candidate;
L
Linus Torvalds 已提交
107

108
	_enter("%p,"NIPQUAD_FMT, cell, NIPQUAD(addr->s_addr));
L
Linus Torvalds 已提交
109

110 111
	/* quick scan of the list to see if we already have the server */
	read_lock(&cell->servers_lock);
L
Linus Torvalds 已提交
112

113 114 115
	list_for_each_entry(server, &cell->servers, link) {
		if (server->addr.s_addr == addr->s_addr)
			goto found_server_quickly;
L
Linus Torvalds 已提交
116
	}
117
	read_unlock(&cell->servers_lock);
L
Linus Torvalds 已提交
118

119 120 121 122
	candidate = afs_alloc_server(cell, addr);
	if (!candidate) {
		_leave(" = -ENOMEM");
		return ERR_PTR(-ENOMEM);
L
Linus Torvalds 已提交
123 124
	}

125
	write_lock(&cell->servers_lock);
L
Linus Torvalds 已提交
126

127 128 129 130 131 132 133 134 135 136
	/* check the cell's server list again */
	list_for_each_entry(server, &cell->servers, link) {
		if (server->addr.s_addr == addr->s_addr)
			goto found_server;
	}

	_debug("new");
	server = candidate;
	if (afs_install_server(server) < 0)
		goto server_in_two_cells;
L
Linus Torvalds 已提交
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
	afs_get_cell(cell);
	list_add_tail(&server->link, &cell->servers);

	write_unlock(&cell->servers_lock);
	_leave(" = %p{%d}", server, atomic_read(&server->usage));
	return server;

	/* found a matching server quickly */
found_server_quickly:
	_debug("found quickly");
	afs_get_server(server);
	read_unlock(&cell->servers_lock);
no_longer_unused:
	if (!list_empty(&server->grave)) {
		spin_lock(&afs_server_graveyard_lock);
		list_del_init(&server->grave);
		spin_unlock(&afs_server_graveyard_lock);
	}
	_leave(" = %p{%d}", server, atomic_read(&server->usage));
	return server;

	/* found a matching server on the second pass */
found_server:
	_debug("found");
	afs_get_server(server);
	write_unlock(&cell->servers_lock);
	kfree(candidate);
	goto no_longer_unused;

	/* found a server that seems to be in two cells */
server_in_two_cells:
	write_unlock(&cell->servers_lock);
	kfree(candidate);
	printk(KERN_NOTICE "kAFS:"
	       " Server "NIPQUAD_FMT" appears to be in two cells\n",
	       NIPQUAD(*addr));
	_leave(" = -EEXIST");
	return ERR_PTR(-EEXIST);
}
L
Linus Torvalds 已提交
177

178 179 180 181 182 183 184 185
/*
 * look up a server by its IP address
 */
struct afs_server *afs_find_server(const struct in_addr *_addr)
{
	struct afs_server *server = NULL;
	struct rb_node *p;
	struct in_addr addr = *_addr;
L
Linus Torvalds 已提交
186

187
	_enter(NIPQUAD_FMT, NIPQUAD(addr.s_addr));
L
Linus Torvalds 已提交
188

189
	read_lock(&afs_servers_lock);
L
Linus Torvalds 已提交
190

191 192 193
	p = afs_servers.rb_node;
	while (p) {
		server = rb_entry(p, struct afs_server, master_rb);
L
Linus Torvalds 已提交
194

195
		_debug("- consider %p", p);
L
Linus Torvalds 已提交
196

197 198 199 200 201 202 203 204 205
		if (addr.s_addr < server->addr.s_addr) {
			p = p->rb_left;
		} else if (addr.s_addr > server->addr.s_addr) {
			p = p->rb_right;
		} else {
			afs_get_server(server);
			goto found;
		}
	}
L
Linus Torvalds 已提交
206

207 208 209 210 211 212
	server = NULL;
found:
	read_unlock(&afs_servers_lock);
	ASSERTIFCMP(server, server->addr.s_addr, ==, addr.s_addr);
	_leave(" = %p", server);
	return server;
D
David Howells 已提交
213
}
L
Linus Torvalds 已提交
214 215 216 217 218 219 220 221 222 223

/*
 * destroy a server record
 * - removes from the cell list
 */
void afs_put_server(struct afs_server *server)
{
	if (!server)
		return;

224
	_enter("%p{%d}", server, atomic_read(&server->usage));
L
Linus Torvalds 已提交
225

226
	ASSERTCMP(atomic_read(&server->usage), >, 0);
L
Linus Torvalds 已提交
227 228 229 230 231 232

	if (likely(!atomic_dec_and_test(&server->usage))) {
		_leave("");
		return;
	}

233
	afs_flush_callback_breaks(server);
L
Linus Torvalds 已提交
234

235 236 237 238 239 240 241 242 243
	spin_lock(&afs_server_graveyard_lock);
	if (atomic_read(&server->usage) == 0) {
		list_move_tail(&server->grave, &afs_server_graveyard);
		server->time_of_death = get_seconds();
		schedule_delayed_work(&afs_server_reaper,
				      afs_server_timeout * HZ);
	}
	spin_unlock(&afs_server_graveyard_lock);
	_leave(" [dead]");
D
David Howells 已提交
244
}
L
Linus Torvalds 已提交
245 246

/*
247
 * destroy a dead server
L
Linus Torvalds 已提交
248
 */
249
static void afs_destroy_server(struct afs_server *server)
L
Linus Torvalds 已提交
250 251 252
{
	_enter("%p", server);

253 254 255 256
	ASSERTCMP(server->fs_vnodes.rb_node, ==, NULL);
	ASSERTCMP(server->cb_promises.rb_node, ==, NULL);
	ASSERTCMP(server->cb_break_head, ==, server->cb_break_tail);
	ASSERTCMP(atomic_read(&server->cb_break_n), ==, 0);
L
Linus Torvalds 已提交
257

258
	afs_put_cell(server->cell);
L
Linus Torvalds 已提交
259
	kfree(server);
D
David Howells 已提交
260
}
L
Linus Torvalds 已提交
261 262

/*
263
 * reap dead server records
L
Linus Torvalds 已提交
264
 */
265
static void afs_reap_server(struct work_struct *work)
L
Linus Torvalds 已提交
266
{
267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288
	LIST_HEAD(corpses);
	struct afs_server *server;
	unsigned long delay, expiry;
	time_t now;

	now = get_seconds();
	spin_lock(&afs_server_graveyard_lock);

	while (!list_empty(&afs_server_graveyard)) {
		server = list_entry(afs_server_graveyard.next,
				    struct afs_server, grave);

		/* the queue is ordered most dead first */
		expiry = server->time_of_death + afs_server_timeout;
		if (expiry > now) {
			delay = (expiry - now) * HZ;
			if (!schedule_delayed_work(&afs_server_reaper, delay)) {
				cancel_delayed_work(&afs_server_reaper);
				schedule_delayed_work(&afs_server_reaper,
						      delay);
			}
			break;
L
Linus Torvalds 已提交
289 290
		}

291 292 293 294 295 296 297 298
		write_lock(&server->cell->servers_lock);
		write_lock(&afs_servers_lock);
		if (atomic_read(&server->usage) > 0) {
			list_del_init(&server->grave);
		} else {
			list_move_tail(&server->grave, &corpses);
			list_del_init(&server->link);
			rb_erase(&server->master_rb, &afs_servers);
L
Linus Torvalds 已提交
299
		}
300 301
		write_unlock(&afs_servers_lock);
		write_unlock(&server->cell->servers_lock);
L
Linus Torvalds 已提交
302 303
	}

304
	spin_unlock(&afs_server_graveyard_lock);
L
Linus Torvalds 已提交
305

306 307 308 309 310
	/* now reap the corpses we've extracted */
	while (!list_empty(&corpses)) {
		server = list_entry(corpses.next, struct afs_server, grave);
		list_del(&server->grave);
		afs_destroy_server(server);
L
Linus Torvalds 已提交
311
	}
D
David Howells 已提交
312
}
L
Linus Torvalds 已提交
313 314

/*
315
 * discard all the server records for rmmod
L
Linus Torvalds 已提交
316
 */
317
void __exit afs_purge_servers(void)
L
Linus Torvalds 已提交
318
{
319 320 321
	afs_server_timeout = 0;
	cancel_delayed_work(&afs_server_reaper);
	schedule_delayed_work(&afs_server_reaper, 0);
D
David Howells 已提交
322
}