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David Howellsec268152007-04-26 15:49:28 -07001/* AFS server record management
Linus Torvalds1da177e2005-04-16 15:20:36 -07002 *
David Howells08e0e7c2007-04-26 15:55:03 -07003 * Copyright (C) 2002, 2007 Red Hat, Inc. All Rights Reserved.
Linus Torvalds1da177e2005-04-16 15:20:36 -07004 * 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 License
8 * as published by the Free Software Foundation; either version
9 * 2 of the License, or (at your option) any later version.
10 */
11
12#include <linux/sched.h>
13#include <linux/slab.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070014#include "internal.h"
15
David Howells08e0e7c2007-04-26 15:55:03 -070016unsigned afs_server_timeout = 10; /* server timeout in seconds */
Linus Torvalds1da177e2005-04-16 15:20:36 -070017
David Howells08e0e7c2007-04-26 15:55:03 -070018static void afs_reap_server(struct work_struct *);
Linus Torvalds1da177e2005-04-16 15:20:36 -070019
David Howells08e0e7c2007-04-26 15:55:03 -070020/* tree of all the servers, indexed by IP address */
21static struct rb_root afs_servers = RB_ROOT;
22static DEFINE_RWLOCK(afs_servers_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -070023
David Howells08e0e7c2007-04-26 15:55:03 -070024/* LRU list of all the servers not currently in use */
25static LIST_HEAD(afs_server_graveyard);
26static DEFINE_SPINLOCK(afs_server_graveyard_lock);
27static DECLARE_DELAYED_WORK(afs_server_reaper, afs_reap_server);
Linus Torvalds1da177e2005-04-16 15:20:36 -070028
Linus Torvalds1da177e2005-04-16 15:20:36 -070029/*
David Howells08e0e7c2007-04-26 15:55:03 -070030 * install a server record in the master tree
Linus Torvalds1da177e2005-04-16 15:20:36 -070031 */
David Howells08e0e7c2007-04-26 15:55:03 -070032static int afs_install_server(struct afs_server *server)
Linus Torvalds1da177e2005-04-16 15:20:36 -070033{
David Howells08e0e7c2007-04-26 15:55:03 -070034 struct afs_server *xserver;
35 struct rb_node **pp, *p;
36 int ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -070037
David Howells08e0e7c2007-04-26 15:55:03 -070038 _enter("%p", server);
Linus Torvalds1da177e2005-04-16 15:20:36 -070039
David Howells08e0e7c2007-04-26 15:55:03 -070040 write_lock(&afs_servers_lock);
41
42 ret = -EEXIST;
43 pp = &afs_servers.rb_node;
44 p = NULL;
45 while (*pp) {
46 p = *pp;
47 _debug("- consider %p", p);
48 xserver = rb_entry(p, struct afs_server, master_rb);
49 if (server->addr.s_addr < xserver->addr.s_addr)
50 pp = &(*pp)->rb_left;
51 else if (server->addr.s_addr > xserver->addr.s_addr)
52 pp = &(*pp)->rb_right;
53 else
54 goto error;
55 }
56
57 rb_link_node(&server->master_rb, p, pp);
58 rb_insert_color(&server->master_rb, &afs_servers);
59 ret = 0;
60
61error:
62 write_unlock(&afs_servers_lock);
63 return ret;
64}
65
66/*
67 * allocate a new server record
68 */
69static struct afs_server *afs_alloc_server(struct afs_cell *cell,
70 const struct in_addr *addr)
71{
72 struct afs_server *server;
73
74 _enter("");
75
Yan Burmanb593e482006-12-06 20:40:32 -080076 server = kzalloc(sizeof(struct afs_server), GFP_KERNEL);
David Howells08e0e7c2007-04-26 15:55:03 -070077 if (server) {
78 atomic_set(&server->usage, 1);
79 server->cell = cell;
80
81 INIT_LIST_HEAD(&server->link);
82 INIT_LIST_HEAD(&server->grave);
83 init_rwsem(&server->sem);
84 spin_lock_init(&server->fs_lock);
85 server->fs_vnodes = RB_ROOT;
86 server->cb_promises = RB_ROOT;
87 spin_lock_init(&server->cb_lock);
88 init_waitqueue_head(&server->cb_break_waitq);
89 INIT_DELAYED_WORK(&server->cb_break_work,
90 afs_dispatch_give_up_callbacks);
91
92 memcpy(&server->addr, addr, sizeof(struct in_addr));
93 server->addr.s_addr = addr->s_addr;
94 }
95
96 _leave(" = %p{%d}", server, atomic_read(&server->usage));
97 return server;
98}
99
100/*
101 * get an FS-server record for a cell
102 */
103struct afs_server *afs_lookup_server(struct afs_cell *cell,
104 const struct in_addr *addr)
105{
106 struct afs_server *server, *candidate;
107
108 _enter("%p,"NIPQUAD_FMT, cell, NIPQUAD(addr->s_addr));
109
110 /* quick scan of the list to see if we already have the server */
111 read_lock(&cell->servers_lock);
112
113 list_for_each_entry(server, &cell->servers, link) {
114 if (server->addr.s_addr == addr->s_addr)
115 goto found_server_quickly;
116 }
117 read_unlock(&cell->servers_lock);
118
119 candidate = afs_alloc_server(cell, addr);
120 if (!candidate) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700121 _leave(" = -ENOMEM");
David Howells08e0e7c2007-04-26 15:55:03 -0700122 return ERR_PTR(-ENOMEM);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700123 }
124
David Howells08e0e7c2007-04-26 15:55:03 -0700125 write_lock(&cell->servers_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700126
David Howells08e0e7c2007-04-26 15:55:03 -0700127 /* check the cell's server list again */
128 list_for_each_entry(server, &cell->servers, link) {
129 if (server->addr.s_addr == addr->s_addr)
130 goto found_server;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700131 }
132
David Howells08e0e7c2007-04-26 15:55:03 -0700133 _debug("new");
134 server = candidate;
135 if (afs_install_server(server) < 0)
136 goto server_in_two_cells;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700137
138 afs_get_cell(cell);
David Howells08e0e7c2007-04-26 15:55:03 -0700139 list_add_tail(&server->link, &cell->servers);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700140
David Howells08e0e7c2007-04-26 15:55:03 -0700141 write_unlock(&cell->servers_lock);
142 _leave(" = %p{%d}", server, atomic_read(&server->usage));
143 return server;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700144
David Howells08e0e7c2007-04-26 15:55:03 -0700145 /* found a matching server quickly */
146found_server_quickly:
147 _debug("found quickly");
148 afs_get_server(server);
149 read_unlock(&cell->servers_lock);
150no_longer_unused:
151 if (!list_empty(&server->grave)) {
152 spin_lock(&afs_server_graveyard_lock);
153 list_del_init(&server->grave);
154 spin_unlock(&afs_server_graveyard_lock);
155 }
156 _leave(" = %p{%d}", server, atomic_read(&server->usage));
157 return server;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700158
David Howells08e0e7c2007-04-26 15:55:03 -0700159 /* found a matching server on the second pass */
160found_server:
161 _debug("found");
162 afs_get_server(server);
163 write_unlock(&cell->servers_lock);
164 kfree(candidate);
165 goto no_longer_unused;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700166
David Howells08e0e7c2007-04-26 15:55:03 -0700167 /* found a server that seems to be in two cells */
168server_in_two_cells:
169 write_unlock(&cell->servers_lock);
170 kfree(candidate);
171 printk(KERN_NOTICE "kAFS:"
172 " Server "NIPQUAD_FMT" appears to be in two cells\n",
173 NIPQUAD(*addr));
174 _leave(" = -EEXIST");
175 return ERR_PTR(-EEXIST);
176}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700177
David Howells08e0e7c2007-04-26 15:55:03 -0700178/*
179 * look up a server by its IP address
180 */
181struct afs_server *afs_find_server(const struct in_addr *_addr)
182{
183 struct afs_server *server = NULL;
184 struct rb_node *p;
185 struct in_addr addr = *_addr;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700186
David Howells08e0e7c2007-04-26 15:55:03 -0700187 _enter(NIPQUAD_FMT, NIPQUAD(addr.s_addr));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700188
David Howells08e0e7c2007-04-26 15:55:03 -0700189 read_lock(&afs_servers_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700190
David Howells08e0e7c2007-04-26 15:55:03 -0700191 p = afs_servers.rb_node;
192 while (p) {
193 server = rb_entry(p, struct afs_server, master_rb);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700194
David Howells08e0e7c2007-04-26 15:55:03 -0700195 _debug("- consider %p", p);
196
197 if (addr.s_addr < server->addr.s_addr) {
198 p = p->rb_left;
199 } else if (addr.s_addr > server->addr.s_addr) {
200 p = p->rb_right;
201 } else {
202 afs_get_server(server);
203 goto found;
204 }
205 }
206
207 server = NULL;
208found:
209 read_unlock(&afs_servers_lock);
210 ASSERTIFCMP(server, server->addr.s_addr, ==, addr.s_addr);
211 _leave(" = %p", server);
212 return server;
David Howellsec268152007-04-26 15:49:28 -0700213}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700214
Linus Torvalds1da177e2005-04-16 15:20:36 -0700215/*
216 * destroy a server record
217 * - removes from the cell list
218 */
219void afs_put_server(struct afs_server *server)
220{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700221 if (!server)
222 return;
223
David Howells08e0e7c2007-04-26 15:55:03 -0700224 _enter("%p{%d}", server, atomic_read(&server->usage));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700225
David Howells260a9802007-04-26 15:59:35 -0700226 _debug("PUT SERVER %d", atomic_read(&server->usage));
227
David Howells08e0e7c2007-04-26 15:55:03 -0700228 ASSERTCMP(atomic_read(&server->usage), >, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700229
230 if (likely(!atomic_dec_and_test(&server->usage))) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700231 _leave("");
232 return;
233 }
234
David Howells08e0e7c2007-04-26 15:55:03 -0700235 afs_flush_callback_breaks(server);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700236
David Howells08e0e7c2007-04-26 15:55:03 -0700237 spin_lock(&afs_server_graveyard_lock);
238 if (atomic_read(&server->usage) == 0) {
239 list_move_tail(&server->grave, &afs_server_graveyard);
240 server->time_of_death = get_seconds();
241 schedule_delayed_work(&afs_server_reaper,
242 afs_server_timeout * HZ);
243 }
244 spin_unlock(&afs_server_graveyard_lock);
245 _leave(" [dead]");
David Howellsec268152007-04-26 15:49:28 -0700246}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700247
Linus Torvalds1da177e2005-04-16 15:20:36 -0700248/*
David Howells08e0e7c2007-04-26 15:55:03 -0700249 * destroy a dead server
Linus Torvalds1da177e2005-04-16 15:20:36 -0700250 */
David Howells08e0e7c2007-04-26 15:55:03 -0700251static void afs_destroy_server(struct afs_server *server)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700252{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700253 _enter("%p", server);
254
David Howells08e0e7c2007-04-26 15:55:03 -0700255 ASSERTCMP(server->fs_vnodes.rb_node, ==, NULL);
256 ASSERTCMP(server->cb_promises.rb_node, ==, NULL);
257 ASSERTCMP(server->cb_break_head, ==, server->cb_break_tail);
258 ASSERTCMP(atomic_read(&server->cb_break_n), ==, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700259
David Howells08e0e7c2007-04-26 15:55:03 -0700260 afs_put_cell(server->cell);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700261 kfree(server);
David Howellsec268152007-04-26 15:49:28 -0700262}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700263
Linus Torvalds1da177e2005-04-16 15:20:36 -0700264/*
David Howells08e0e7c2007-04-26 15:55:03 -0700265 * reap dead server records
Linus Torvalds1da177e2005-04-16 15:20:36 -0700266 */
David Howells08e0e7c2007-04-26 15:55:03 -0700267static void afs_reap_server(struct work_struct *work)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700268{
David Howells08e0e7c2007-04-26 15:55:03 -0700269 LIST_HEAD(corpses);
270 struct afs_server *server;
271 unsigned long delay, expiry;
272 time_t now;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700273
David Howells08e0e7c2007-04-26 15:55:03 -0700274 now = get_seconds();
275 spin_lock(&afs_server_graveyard_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700276
David Howells08e0e7c2007-04-26 15:55:03 -0700277 while (!list_empty(&afs_server_graveyard)) {
278 server = list_entry(afs_server_graveyard.next,
279 struct afs_server, grave);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700280
David Howells08e0e7c2007-04-26 15:55:03 -0700281 /* the queue is ordered most dead first */
282 expiry = server->time_of_death + afs_server_timeout;
283 if (expiry > now) {
284 delay = (expiry - now) * HZ;
285 if (!schedule_delayed_work(&afs_server_reaper, delay)) {
286 cancel_delayed_work(&afs_server_reaper);
287 schedule_delayed_work(&afs_server_reaper,
288 delay);
289 }
290 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700291 }
292
David Howells08e0e7c2007-04-26 15:55:03 -0700293 write_lock(&server->cell->servers_lock);
294 write_lock(&afs_servers_lock);
295 if (atomic_read(&server->usage) > 0) {
296 list_del_init(&server->grave);
297 } else {
298 list_move_tail(&server->grave, &corpses);
299 list_del_init(&server->link);
300 rb_erase(&server->master_rb, &afs_servers);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700301 }
David Howells08e0e7c2007-04-26 15:55:03 -0700302 write_unlock(&afs_servers_lock);
303 write_unlock(&server->cell->servers_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700304 }
305
David Howells08e0e7c2007-04-26 15:55:03 -0700306 spin_unlock(&afs_server_graveyard_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700307
David Howells08e0e7c2007-04-26 15:55:03 -0700308 /* now reap the corpses we've extracted */
309 while (!list_empty(&corpses)) {
310 server = list_entry(corpses.next, struct afs_server, grave);
311 list_del(&server->grave);
312 afs_destroy_server(server);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700313 }
David Howellsec268152007-04-26 15:49:28 -0700314}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700315
Linus Torvalds1da177e2005-04-16 15:20:36 -0700316/*
David Howells08e0e7c2007-04-26 15:55:03 -0700317 * discard all the server records for rmmod
Linus Torvalds1da177e2005-04-16 15:20:36 -0700318 */
David Howells08e0e7c2007-04-26 15:55:03 -0700319void __exit afs_purge_servers(void)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700320{
David Howells08e0e7c2007-04-26 15:55:03 -0700321 afs_server_timeout = 0;
322 cancel_delayed_work(&afs_server_reaper);
323 schedule_delayed_work(&afs_server_reaper, 0);
David Howellsec268152007-04-26 15:49:28 -0700324}