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1/* AFS server record management
2 *
3 * Copyright (C) 2002, 2007 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 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>
14#include "internal.h"
15
16static unsigned afs_server_timeout = 10; /* server timeout in seconds */
17
18static void afs_reap_server(struct work_struct *);
19
20/* tree of all the servers, indexed by IP address */
21static struct rb_root afs_servers = RB_ROOT;
22static DEFINE_RWLOCK(afs_servers_lock);
23
24/* 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);
28
29/*
30 * install a server record in the master tree
31 */
32static int afs_install_server(struct afs_server *server)
33{
34 struct afs_server *xserver;
35 struct rb_node **pp, *p;
36 int ret;
37
38 _enter("%p", server);
39
40 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
76 server = kzalloc(sizeof(struct afs_server), GFP_KERNEL);
77 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 _leave(" = %p{%d}", server, atomic_read(&server->usage));
95 } else {
96 _leave(" = NULL [nomem]");
97 }
98 return server;
99}
100
101/*
102 * get an FS-server record for a cell
103 */
104struct afs_server *afs_lookup_server(struct afs_cell *cell,
105 const struct in_addr *addr)
106{
107 struct afs_server *server, *candidate;
108
109 _enter("%p,%pI4", cell, &addr->s_addr);
110
111 /* quick scan of the list to see if we already have the server */
112 read_lock(&cell->servers_lock);
113
114 list_for_each_entry(server, &cell->servers, link) {
115 if (server->addr.s_addr == addr->s_addr)
116 goto found_server_quickly;
117 }
118 read_unlock(&cell->servers_lock);
119
120 candidate = afs_alloc_server(cell, addr);
121 if (!candidate) {
122 _leave(" = -ENOMEM");
123 return ERR_PTR(-ENOMEM);
124 }
125
126 write_lock(&cell->servers_lock);
127
128 /* check the cell's server list again */
129 list_for_each_entry(server, &cell->servers, link) {
130 if (server->addr.s_addr == addr->s_addr)
131 goto found_server;
132 }
133
134 _debug("new");
135 server = candidate;
136 if (afs_install_server(server) < 0)
137 goto server_in_two_cells;
138
139 afs_get_cell(cell);
140 list_add_tail(&server->link, &cell->servers);
141
142 write_unlock(&cell->servers_lock);
143 _leave(" = %p{%d}", server, atomic_read(&server->usage));
144 return server;
145
146 /* found a matching server quickly */
147found_server_quickly:
148 _debug("found quickly");
149 afs_get_server(server);
150 read_unlock(&cell->servers_lock);
151no_longer_unused:
152 if (!list_empty(&server->grave)) {
153 spin_lock(&afs_server_graveyard_lock);
154 list_del_init(&server->grave);
155 spin_unlock(&afs_server_graveyard_lock);
156 }
157 _leave(" = %p{%d}", server, atomic_read(&server->usage));
158 return server;
159
160 /* found a matching server on the second pass */
161found_server:
162 _debug("found");
163 afs_get_server(server);
164 write_unlock(&cell->servers_lock);
165 kfree(candidate);
166 goto no_longer_unused;
167
168 /* found a server that seems to be in two cells */
169server_in_two_cells:
170 write_unlock(&cell->servers_lock);
171 kfree(candidate);
172 printk(KERN_NOTICE "kAFS: Server %pI4 appears to be in two cells\n",
173 addr);
174 _leave(" = -EEXIST");
175 return ERR_PTR(-EEXIST);
176}
177
178/*
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;
186
187 _enter("%pI4", &addr.s_addr);
188
189 read_lock(&afs_servers_lock);
190
191 p = afs_servers.rb_node;
192 while (p) {
193 server = rb_entry(p, struct afs_server, master_rb);
194
195 _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;
213}
214
215/*
216 * destroy a server record
217 * - removes from the cell list
218 */
219void afs_put_server(struct afs_server *server)
220{
221 if (!server)
222 return;
223
224 _enter("%p{%d}", server, atomic_read(&server->usage));
225
226 _debug("PUT SERVER %d", atomic_read(&server->usage));
227
228 ASSERTCMP(atomic_read(&server->usage), >, 0);
229
230 if (likely(!atomic_dec_and_test(&server->usage))) {
231 _leave("");
232 return;
233 }
234
235 afs_flush_callback_breaks(server);
236
237 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 queue_delayed_work(afs_wq, &afs_server_reaper,
242 afs_server_timeout * HZ);
243 }
244 spin_unlock(&afs_server_graveyard_lock);
245 _leave(" [dead]");
246}
247
248/*
249 * destroy a dead server
250 */
251static void afs_destroy_server(struct afs_server *server)
252{
253 _enter("%p", server);
254
255 ASSERTIF(server->cb_break_head != server->cb_break_tail,
256 delayed_work_pending(&server->cb_break_work));
257
258 ASSERTCMP(server->fs_vnodes.rb_node, ==, NULL);
259 ASSERTCMP(server->cb_promises.rb_node, ==, NULL);
260 ASSERTCMP(server->cb_break_head, ==, server->cb_break_tail);
261 ASSERTCMP(atomic_read(&server->cb_break_n), ==, 0);
262
263 afs_put_cell(server->cell);
264 kfree(server);
265}
266
267/*
268 * reap dead server records
269 */
270static void afs_reap_server(struct work_struct *work)
271{
272 LIST_HEAD(corpses);
273 struct afs_server *server;
274 unsigned long delay, expiry;
275 time_t now;
276
277 now = get_seconds();
278 spin_lock(&afs_server_graveyard_lock);
279
280 while (!list_empty(&afs_server_graveyard)) {
281 server = list_entry(afs_server_graveyard.next,
282 struct afs_server, grave);
283
284 /* the queue is ordered most dead first */
285 expiry = server->time_of_death + afs_server_timeout;
286 if (expiry > now) {
287 delay = (expiry - now) * HZ;
288 if (!queue_delayed_work(afs_wq, &afs_server_reaper,
289 delay)) {
290 cancel_delayed_work(&afs_server_reaper);
291 queue_delayed_work(afs_wq, &afs_server_reaper,
292 delay);
293 }
294 break;
295 }
296
297 write_lock(&server->cell->servers_lock);
298 write_lock(&afs_servers_lock);
299 if (atomic_read(&server->usage) > 0) {
300 list_del_init(&server->grave);
301 } else {
302 list_move_tail(&server->grave, &corpses);
303 list_del_init(&server->link);
304 rb_erase(&server->master_rb, &afs_servers);
305 }
306 write_unlock(&afs_servers_lock);
307 write_unlock(&server->cell->servers_lock);
308 }
309
310 spin_unlock(&afs_server_graveyard_lock);
311
312 /* now reap the corpses we've extracted */
313 while (!list_empty(&corpses)) {
314 server = list_entry(corpses.next, struct afs_server, grave);
315 list_del(&server->grave);
316 afs_destroy_server(server);
317 }
318}
319
320/*
321 * discard all the server records for rmmod
322 */
323void __exit afs_purge_servers(void)
324{
325 afs_server_timeout = 0;
326 cancel_delayed_work(&afs_server_reaper);
327 queue_delayed_work(afs_wq, &afs_server_reaper, 0);
328}
1/* AFS server record management
2 *
3 * Copyright (C) 2002, 2007 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 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>
14#include "internal.h"
15
16static unsigned afs_server_timeout = 10; /* server timeout in seconds */
17
18static void afs_reap_server(struct work_struct *);
19
20/* tree of all the servers, indexed by IP address */
21static struct rb_root afs_servers = RB_ROOT;
22static DEFINE_RWLOCK(afs_servers_lock);
23
24/* 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);
28
29/*
30 * install a server record in the master tree
31 */
32static int afs_install_server(struct afs_server *server)
33{
34 struct afs_server *xserver;
35 struct rb_node **pp, *p;
36 int ret;
37
38 _enter("%p", server);
39
40 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
76 server = kzalloc(sizeof(struct afs_server), GFP_KERNEL);
77 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 _leave(" = %p{%d}", server, atomic_read(&server->usage));
95 } else {
96 _leave(" = NULL [nomem]");
97 }
98 return server;
99}
100
101/*
102 * get an FS-server record for a cell
103 */
104struct afs_server *afs_lookup_server(struct afs_cell *cell,
105 const struct in_addr *addr)
106{
107 struct afs_server *server, *candidate;
108
109 _enter("%p,%pI4", cell, &addr->s_addr);
110
111 /* quick scan of the list to see if we already have the server */
112 read_lock(&cell->servers_lock);
113
114 list_for_each_entry(server, &cell->servers, link) {
115 if (server->addr.s_addr == addr->s_addr)
116 goto found_server_quickly;
117 }
118 read_unlock(&cell->servers_lock);
119
120 candidate = afs_alloc_server(cell, addr);
121 if (!candidate) {
122 _leave(" = -ENOMEM");
123 return ERR_PTR(-ENOMEM);
124 }
125
126 write_lock(&cell->servers_lock);
127
128 /* check the cell's server list again */
129 list_for_each_entry(server, &cell->servers, link) {
130 if (server->addr.s_addr == addr->s_addr)
131 goto found_server;
132 }
133
134 _debug("new");
135 server = candidate;
136 if (afs_install_server(server) < 0)
137 goto server_in_two_cells;
138
139 afs_get_cell(cell);
140 list_add_tail(&server->link, &cell->servers);
141
142 write_unlock(&cell->servers_lock);
143 _leave(" = %p{%d}", server, atomic_read(&server->usage));
144 return server;
145
146 /* found a matching server quickly */
147found_server_quickly:
148 _debug("found quickly");
149 afs_get_server(server);
150 read_unlock(&cell->servers_lock);
151no_longer_unused:
152 if (!list_empty(&server->grave)) {
153 spin_lock(&afs_server_graveyard_lock);
154 list_del_init(&server->grave);
155 spin_unlock(&afs_server_graveyard_lock);
156 }
157 _leave(" = %p{%d}", server, atomic_read(&server->usage));
158 return server;
159
160 /* found a matching server on the second pass */
161found_server:
162 _debug("found");
163 afs_get_server(server);
164 write_unlock(&cell->servers_lock);
165 kfree(candidate);
166 goto no_longer_unused;
167
168 /* found a server that seems to be in two cells */
169server_in_two_cells:
170 write_unlock(&cell->servers_lock);
171 kfree(candidate);
172 printk(KERN_NOTICE "kAFS: Server %pI4 appears to be in two cells\n",
173 addr);
174 _leave(" = -EEXIST");
175 return ERR_PTR(-EEXIST);
176}
177
178/*
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;
186
187 _enter("%pI4", &addr.s_addr);
188
189 read_lock(&afs_servers_lock);
190
191 p = afs_servers.rb_node;
192 while (p) {
193 server = rb_entry(p, struct afs_server, master_rb);
194
195 _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;
213}
214
215/*
216 * destroy a server record
217 * - removes from the cell list
218 */
219void afs_put_server(struct afs_server *server)
220{
221 if (!server)
222 return;
223
224 _enter("%p{%d}", server, atomic_read(&server->usage));
225
226 _debug("PUT SERVER %d", atomic_read(&server->usage));
227
228 ASSERTCMP(atomic_read(&server->usage), >, 0);
229
230 if (likely(!atomic_dec_and_test(&server->usage))) {
231 _leave("");
232 return;
233 }
234
235 afs_flush_callback_breaks(server);
236
237 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 queue_delayed_work(afs_wq, &afs_server_reaper,
242 afs_server_timeout * HZ);
243 }
244 spin_unlock(&afs_server_graveyard_lock);
245 _leave(" [dead]");
246}
247
248/*
249 * destroy a dead server
250 */
251static void afs_destroy_server(struct afs_server *server)
252{
253 _enter("%p", server);
254
255 ASSERTIF(server->cb_break_head != server->cb_break_tail,
256 delayed_work_pending(&server->cb_break_work));
257
258 ASSERTCMP(server->fs_vnodes.rb_node, ==, NULL);
259 ASSERTCMP(server->cb_promises.rb_node, ==, NULL);
260 ASSERTCMP(server->cb_break_head, ==, server->cb_break_tail);
261 ASSERTCMP(atomic_read(&server->cb_break_n), ==, 0);
262
263 afs_put_cell(server->cell);
264 kfree(server);
265}
266
267/*
268 * reap dead server records
269 */
270static void afs_reap_server(struct work_struct *work)
271{
272 LIST_HEAD(corpses);
273 struct afs_server *server;
274 unsigned long delay, expiry;
275 time_t now;
276
277 now = get_seconds();
278 spin_lock(&afs_server_graveyard_lock);
279
280 while (!list_empty(&afs_server_graveyard)) {
281 server = list_entry(afs_server_graveyard.next,
282 struct afs_server, grave);
283
284 /* the queue is ordered most dead first */
285 expiry = server->time_of_death + afs_server_timeout;
286 if (expiry > now) {
287 delay = (expiry - now) * HZ;
288 mod_delayed_work(afs_wq, &afs_server_reaper, delay);
289 break;
290 }
291
292 write_lock(&server->cell->servers_lock);
293 write_lock(&afs_servers_lock);
294 if (atomic_read(&server->usage) > 0) {
295 list_del_init(&server->grave);
296 } else {
297 list_move_tail(&server->grave, &corpses);
298 list_del_init(&server->link);
299 rb_erase(&server->master_rb, &afs_servers);
300 }
301 write_unlock(&afs_servers_lock);
302 write_unlock(&server->cell->servers_lock);
303 }
304
305 spin_unlock(&afs_server_graveyard_lock);
306
307 /* now reap the corpses we've extracted */
308 while (!list_empty(&corpses)) {
309 server = list_entry(corpses.next, struct afs_server, grave);
310 list_del(&server->grave);
311 afs_destroy_server(server);
312 }
313}
314
315/*
316 * discard all the server records for rmmod
317 */
318void __exit afs_purge_servers(void)
319{
320 afs_server_timeout = 0;
321 mod_delayed_work(afs_wq, &afs_server_reaper, 0);
322}