fs: replace NIPQUAD()
[linux-2.6.git] / fs / afs / server.c
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
16 static unsigned afs_server_timeout = 10;        /* server timeout in seconds */
17
18 static void afs_reap_server(struct work_struct *);
19
20 /* tree of all the servers, indexed by IP address */
21 static struct rb_root afs_servers = RB_ROOT;
22 static DEFINE_RWLOCK(afs_servers_lock);
23
24 /* LRU list of all the servers not currently in use */
25 static LIST_HEAD(afs_server_graveyard);
26 static DEFINE_SPINLOCK(afs_server_graveyard_lock);
27 static DECLARE_DELAYED_WORK(afs_server_reaper, afs_reap_server);
28
29 /*
30  * install a server record in the master tree
31  */
32 static 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
61 error:
62         write_unlock(&afs_servers_lock);
63         return ret;
64 }
65
66 /*
67  * allocate a new server record
68  */
69 static 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         }
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  */
103 struct 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,%pI4", cell, &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) {
121                 _leave(" = -ENOMEM");
122                 return ERR_PTR(-ENOMEM);
123         }
124
125         write_lock(&cell->servers_lock);
126
127         /* 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;
131         }
132
133         _debug("new");
134         server = candidate;
135         if (afs_install_server(server) < 0)
136                 goto server_in_two_cells;
137
138         afs_get_cell(cell);
139         list_add_tail(&server->link, &cell->servers);
140
141         write_unlock(&cell->servers_lock);
142         _leave(" = %p{%d}", server, atomic_read(&server->usage));
143         return server;
144
145         /* found a matching server quickly */
146 found_server_quickly:
147         _debug("found quickly");
148         afs_get_server(server);
149         read_unlock(&cell->servers_lock);
150 no_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;
158
159         /* found a matching server on the second pass */
160 found_server:
161         _debug("found");
162         afs_get_server(server);
163         write_unlock(&cell->servers_lock);
164         kfree(candidate);
165         goto no_longer_unused;
166
167         /* found a server that seems to be in two cells */
168 server_in_two_cells:
169         write_unlock(&cell->servers_lock);
170         kfree(candidate);
171         printk(KERN_NOTICE "kAFS: Server %pI4 appears to be in two cells\n",
172                addr);
173         _leave(" = -EEXIST");
174         return ERR_PTR(-EEXIST);
175 }
176
177 /*
178  * look up a server by its IP address
179  */
180 struct afs_server *afs_find_server(const struct in_addr *_addr)
181 {
182         struct afs_server *server = NULL;
183         struct rb_node *p;
184         struct in_addr addr = *_addr;
185
186         _enter("%pI4", &addr.s_addr);
187
188         read_lock(&afs_servers_lock);
189
190         p = afs_servers.rb_node;
191         while (p) {
192                 server = rb_entry(p, struct afs_server, master_rb);
193
194                 _debug("- consider %p", p);
195
196                 if (addr.s_addr < server->addr.s_addr) {
197                         p = p->rb_left;
198                 } else if (addr.s_addr > server->addr.s_addr) {
199                         p = p->rb_right;
200                 } else {
201                         afs_get_server(server);
202                         goto found;
203                 }
204         }
205
206         server = NULL;
207 found:
208         read_unlock(&afs_servers_lock);
209         ASSERTIFCMP(server, server->addr.s_addr, ==, addr.s_addr);
210         _leave(" = %p", server);
211         return server;
212 }
213
214 /*
215  * destroy a server record
216  * - removes from the cell list
217  */
218 void afs_put_server(struct afs_server *server)
219 {
220         if (!server)
221                 return;
222
223         _enter("%p{%d}", server, atomic_read(&server->usage));
224
225         _debug("PUT SERVER %d", atomic_read(&server->usage));
226
227         ASSERTCMP(atomic_read(&server->usage), >, 0);
228
229         if (likely(!atomic_dec_and_test(&server->usage))) {
230                 _leave("");
231                 return;
232         }
233
234         afs_flush_callback_breaks(server);
235
236         spin_lock(&afs_server_graveyard_lock);
237         if (atomic_read(&server->usage) == 0) {
238                 list_move_tail(&server->grave, &afs_server_graveyard);
239                 server->time_of_death = get_seconds();
240                 schedule_delayed_work(&afs_server_reaper,
241                                       afs_server_timeout * HZ);
242         }
243         spin_unlock(&afs_server_graveyard_lock);
244         _leave(" [dead]");
245 }
246
247 /*
248  * destroy a dead server
249  */
250 static void afs_destroy_server(struct afs_server *server)
251 {
252         _enter("%p", server);
253
254         ASSERTIF(server->cb_break_head != server->cb_break_tail,
255                  delayed_work_pending(&server->cb_break_work));
256
257         ASSERTCMP(server->fs_vnodes.rb_node, ==, NULL);
258         ASSERTCMP(server->cb_promises.rb_node, ==, NULL);
259         ASSERTCMP(server->cb_break_head, ==, server->cb_break_tail);
260         ASSERTCMP(atomic_read(&server->cb_break_n), ==, 0);
261
262         afs_put_cell(server->cell);
263         kfree(server);
264 }
265
266 /*
267  * reap dead server records
268  */
269 static void afs_reap_server(struct work_struct *work)
270 {
271         LIST_HEAD(corpses);
272         struct afs_server *server;
273         unsigned long delay, expiry;
274         time_t now;
275
276         now = get_seconds();
277         spin_lock(&afs_server_graveyard_lock);
278
279         while (!list_empty(&afs_server_graveyard)) {
280                 server = list_entry(afs_server_graveyard.next,
281                                     struct afs_server, grave);
282
283                 /* the queue is ordered most dead first */
284                 expiry = server->time_of_death + afs_server_timeout;
285                 if (expiry > now) {
286                         delay = (expiry - now) * HZ;
287                         if (!schedule_delayed_work(&afs_server_reaper, delay)) {
288                                 cancel_delayed_work(&afs_server_reaper);
289                                 schedule_delayed_work(&afs_server_reaper,
290                                                       delay);
291                         }
292                         break;
293                 }
294
295                 write_lock(&server->cell->servers_lock);
296                 write_lock(&afs_servers_lock);
297                 if (atomic_read(&server->usage) > 0) {
298                         list_del_init(&server->grave);
299                 } else {
300                         list_move_tail(&server->grave, &corpses);
301                         list_del_init(&server->link);
302                         rb_erase(&server->master_rb, &afs_servers);
303                 }
304                 write_unlock(&afs_servers_lock);
305                 write_unlock(&server->cell->servers_lock);
306         }
307
308         spin_unlock(&afs_server_graveyard_lock);
309
310         /* now reap the corpses we've extracted */
311         while (!list_empty(&corpses)) {
312                 server = list_entry(corpses.next, struct afs_server, grave);
313                 list_del(&server->grave);
314                 afs_destroy_server(server);
315         }
316 }
317
318 /*
319  * discard all the server records for rmmod
320  */
321 void __exit afs_purge_servers(void)
322 {
323         afs_server_timeout = 0;
324         cancel_delayed_work(&afs_server_reaper);
325         schedule_delayed_work(&afs_server_reaper, 0);
326 }