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1da177e4 LT |
1 | /* server.c: AFS server record management |
2 | * | |
3 | * Copyright (C) 2002 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 <rxrpc/peer.h> | |
15 | #include <rxrpc/connection.h> | |
16 | #include "volume.h" | |
17 | #include "cell.h" | |
18 | #include "server.h" | |
19 | #include "transport.h" | |
20 | #include "vlclient.h" | |
21 | #include "kafstimod.h" | |
22 | #include "internal.h" | |
23 | ||
24 | DEFINE_SPINLOCK(afs_server_peer_lock); | |
25 | ||
26 | #define FS_SERVICE_ID 1 /* AFS Volume Location Service ID */ | |
27 | #define VL_SERVICE_ID 52 /* AFS Volume Location Service ID */ | |
28 | ||
29 | static void __afs_server_timeout(struct afs_timer *timer) | |
30 | { | |
31 | struct afs_server *server = | |
32 | list_entry(timer, struct afs_server, timeout); | |
33 | ||
34 | _debug("SERVER TIMEOUT [%p{u=%d}]", | |
35 | server, atomic_read(&server->usage)); | |
36 | ||
37 | afs_server_do_timeout(server); | |
38 | } | |
39 | ||
40 | static const struct afs_timer_ops afs_server_timer_ops = { | |
41 | .timed_out = __afs_server_timeout, | |
42 | }; | |
43 | ||
44 | /*****************************************************************************/ | |
45 | /* | |
46 | * lookup a server record in a cell | |
47 | * - TODO: search the cell's server list | |
48 | */ | |
49 | int afs_server_lookup(struct afs_cell *cell, const struct in_addr *addr, | |
50 | struct afs_server **_server) | |
51 | { | |
52 | struct afs_server *server, *active, *zombie; | |
53 | int loop; | |
54 | ||
55 | _enter("%p,%08x,", cell, ntohl(addr->s_addr)); | |
56 | ||
57 | /* allocate and initialise a server record */ | |
58 | server = kmalloc(sizeof(struct afs_server), GFP_KERNEL); | |
59 | if (!server) { | |
60 | _leave(" = -ENOMEM"); | |
61 | return -ENOMEM; | |
62 | } | |
63 | ||
64 | memset(server, 0, sizeof(struct afs_server)); | |
65 | atomic_set(&server->usage, 1); | |
66 | ||
67 | INIT_LIST_HEAD(&server->link); | |
68 | init_rwsem(&server->sem); | |
69 | INIT_LIST_HEAD(&server->fs_callq); | |
70 | spin_lock_init(&server->fs_lock); | |
71 | INIT_LIST_HEAD(&server->cb_promises); | |
72 | spin_lock_init(&server->cb_lock); | |
73 | ||
74 | for (loop = 0; loop < AFS_SERVER_CONN_LIST_SIZE; loop++) | |
75 | server->fs_conn_cnt[loop] = 4; | |
76 | ||
77 | memcpy(&server->addr, addr, sizeof(struct in_addr)); | |
78 | server->addr.s_addr = addr->s_addr; | |
79 | ||
80 | afs_timer_init(&server->timeout, &afs_server_timer_ops); | |
81 | ||
82 | /* add to the cell */ | |
83 | write_lock(&cell->sv_lock); | |
84 | ||
85 | /* check the active list */ | |
86 | list_for_each_entry(active, &cell->sv_list, link) { | |
87 | if (active->addr.s_addr == addr->s_addr) | |
88 | goto use_active_server; | |
89 | } | |
90 | ||
91 | /* check the inactive list */ | |
92 | spin_lock(&cell->sv_gylock); | |
93 | list_for_each_entry(zombie, &cell->sv_graveyard, link) { | |
94 | if (zombie->addr.s_addr == addr->s_addr) | |
95 | goto resurrect_server; | |
96 | } | |
97 | spin_unlock(&cell->sv_gylock); | |
98 | ||
99 | afs_get_cell(cell); | |
100 | server->cell = cell; | |
101 | list_add_tail(&server->link, &cell->sv_list); | |
102 | ||
103 | write_unlock(&cell->sv_lock); | |
104 | ||
105 | *_server = server; | |
106 | _leave(" = 0 (%p)", server); | |
107 | return 0; | |
108 | ||
109 | /* found a matching active server */ | |
110 | use_active_server: | |
111 | _debug("active server"); | |
112 | afs_get_server(active); | |
113 | write_unlock(&cell->sv_lock); | |
114 | ||
115 | kfree(server); | |
116 | ||
117 | *_server = active; | |
118 | _leave(" = 0 (%p)", active); | |
119 | return 0; | |
120 | ||
121 | /* found a matching server in the graveyard, so resurrect it and | |
122 | * dispose of the new record */ | |
123 | resurrect_server: | |
124 | _debug("resurrecting server"); | |
125 | ||
126 | list_del(&zombie->link); | |
127 | list_add_tail(&zombie->link, &cell->sv_list); | |
128 | afs_get_server(zombie); | |
129 | afs_kafstimod_del_timer(&zombie->timeout); | |
130 | spin_unlock(&cell->sv_gylock); | |
131 | write_unlock(&cell->sv_lock); | |
132 | ||
133 | kfree(server); | |
134 | ||
135 | *_server = zombie; | |
136 | _leave(" = 0 (%p)", zombie); | |
137 | return 0; | |
138 | ||
139 | } /* end afs_server_lookup() */ | |
140 | ||
141 | /*****************************************************************************/ | |
142 | /* | |
143 | * destroy a server record | |
144 | * - removes from the cell list | |
145 | */ | |
146 | void afs_put_server(struct afs_server *server) | |
147 | { | |
148 | struct afs_cell *cell; | |
149 | ||
150 | if (!server) | |
151 | return; | |
152 | ||
153 | _enter("%p", server); | |
154 | ||
155 | cell = server->cell; | |
156 | ||
157 | /* sanity check */ | |
158 | BUG_ON(atomic_read(&server->usage) <= 0); | |
159 | ||
160 | /* to prevent a race, the decrement and the dequeue must be effectively | |
161 | * atomic */ | |
162 | write_lock(&cell->sv_lock); | |
163 | ||
164 | if (likely(!atomic_dec_and_test(&server->usage))) { | |
165 | write_unlock(&cell->sv_lock); | |
166 | _leave(""); | |
167 | return; | |
168 | } | |
169 | ||
170 | spin_lock(&cell->sv_gylock); | |
171 | list_del(&server->link); | |
172 | list_add_tail(&server->link, &cell->sv_graveyard); | |
173 | ||
174 | /* time out in 10 secs */ | |
175 | afs_kafstimod_add_timer(&server->timeout, 10 * HZ); | |
176 | ||
177 | spin_unlock(&cell->sv_gylock); | |
178 | write_unlock(&cell->sv_lock); | |
179 | ||
180 | _leave(" [killed]"); | |
181 | } /* end afs_put_server() */ | |
182 | ||
183 | /*****************************************************************************/ | |
184 | /* | |
185 | * timeout server record | |
186 | * - removes from the cell's graveyard if the usage count is zero | |
187 | */ | |
188 | void afs_server_do_timeout(struct afs_server *server) | |
189 | { | |
190 | struct rxrpc_peer *peer; | |
191 | struct afs_cell *cell; | |
192 | int loop; | |
193 | ||
194 | _enter("%p", server); | |
195 | ||
196 | cell = server->cell; | |
197 | ||
198 | BUG_ON(atomic_read(&server->usage) < 0); | |
199 | ||
200 | /* remove from graveyard if still dead */ | |
201 | spin_lock(&cell->vl_gylock); | |
202 | if (atomic_read(&server->usage) == 0) | |
203 | list_del_init(&server->link); | |
204 | else | |
205 | server = NULL; | |
206 | spin_unlock(&cell->vl_gylock); | |
207 | ||
208 | if (!server) { | |
209 | _leave(""); | |
210 | return; /* resurrected */ | |
211 | } | |
212 | ||
213 | /* we can now destroy it properly */ | |
214 | afs_put_cell(cell); | |
215 | ||
216 | /* uncross-point the structs under a global lock */ | |
217 | spin_lock(&afs_server_peer_lock); | |
218 | peer = server->peer; | |
219 | if (peer) { | |
220 | server->peer = NULL; | |
221 | peer->user = NULL; | |
222 | } | |
223 | spin_unlock(&afs_server_peer_lock); | |
224 | ||
225 | /* finish cleaning up the server */ | |
226 | for (loop = AFS_SERVER_CONN_LIST_SIZE - 1; loop >= 0; loop--) | |
227 | if (server->fs_conn[loop]) | |
228 | rxrpc_put_connection(server->fs_conn[loop]); | |
229 | ||
230 | if (server->vlserver) | |
231 | rxrpc_put_connection(server->vlserver); | |
232 | ||
233 | kfree(server); | |
234 | ||
235 | _leave(" [destroyed]"); | |
236 | } /* end afs_server_do_timeout() */ | |
237 | ||
238 | /*****************************************************************************/ | |
239 | /* | |
240 | * get a callslot on a connection to the fileserver on the specified server | |
241 | */ | |
242 | int afs_server_request_callslot(struct afs_server *server, | |
243 | struct afs_server_callslot *callslot) | |
244 | { | |
245 | struct afs_server_callslot *pcallslot; | |
246 | struct rxrpc_connection *conn; | |
247 | int nconn, ret; | |
248 | ||
249 | _enter("%p,",server); | |
250 | ||
251 | INIT_LIST_HEAD(&callslot->link); | |
252 | callslot->task = current; | |
253 | callslot->conn = NULL; | |
254 | callslot->nconn = -1; | |
255 | callslot->ready = 0; | |
256 | ||
257 | ret = 0; | |
258 | conn = NULL; | |
259 | ||
260 | /* get hold of a callslot first */ | |
261 | spin_lock(&server->fs_lock); | |
262 | ||
263 | /* resurrect the server if it's death timeout has expired */ | |
264 | if (server->fs_state) { | |
265 | if (time_before(jiffies, server->fs_dead_jif)) { | |
266 | ret = server->fs_state; | |
267 | spin_unlock(&server->fs_lock); | |
268 | _leave(" = %d [still dead]", ret); | |
269 | return ret; | |
270 | } | |
271 | ||
272 | server->fs_state = 0; | |
273 | } | |
274 | ||
275 | /* try and find a connection that has spare callslots */ | |
276 | for (nconn = 0; nconn < AFS_SERVER_CONN_LIST_SIZE; nconn++) { | |
277 | if (server->fs_conn_cnt[nconn] > 0) { | |
278 | server->fs_conn_cnt[nconn]--; | |
279 | spin_unlock(&server->fs_lock); | |
280 | callslot->nconn = nconn; | |
281 | goto obtained_slot; | |
282 | } | |
283 | } | |
284 | ||
285 | /* none were available - wait interruptibly for one to become | |
286 | * available */ | |
287 | set_current_state(TASK_INTERRUPTIBLE); | |
288 | list_add_tail(&callslot->link, &server->fs_callq); | |
289 | spin_unlock(&server->fs_lock); | |
290 | ||
291 | while (!callslot->ready && !signal_pending(current)) { | |
292 | schedule(); | |
293 | set_current_state(TASK_INTERRUPTIBLE); | |
294 | } | |
295 | ||
296 | set_current_state(TASK_RUNNING); | |
297 | ||
298 | /* even if we were interrupted we may still be queued */ | |
299 | if (!callslot->ready) { | |
300 | spin_lock(&server->fs_lock); | |
301 | list_del_init(&callslot->link); | |
302 | spin_unlock(&server->fs_lock); | |
303 | } | |
304 | ||
305 | nconn = callslot->nconn; | |
306 | ||
307 | /* if interrupted, we must release any slot we also got before | |
308 | * returning an error */ | |
309 | if (signal_pending(current)) { | |
310 | ret = -EINTR; | |
311 | goto error_release; | |
312 | } | |
313 | ||
314 | /* if we were woken up with an error, then pass that error back to the | |
315 | * called */ | |
316 | if (nconn < 0) { | |
317 | _leave(" = %d", callslot->errno); | |
318 | return callslot->errno; | |
319 | } | |
320 | ||
321 | /* were we given a connection directly? */ | |
322 | if (callslot->conn) { | |
323 | /* yes - use it */ | |
324 | _leave(" = 0 (nc=%d)", nconn); | |
325 | return 0; | |
326 | } | |
327 | ||
328 | /* got a callslot, but no connection */ | |
329 | obtained_slot: | |
330 | ||
331 | /* need to get hold of the RxRPC connection */ | |
332 | down_write(&server->sem); | |
333 | ||
334 | /* quick check to see if there's an outstanding error */ | |
335 | ret = server->fs_state; | |
336 | if (ret) | |
337 | goto error_release_upw; | |
338 | ||
339 | if (server->fs_conn[nconn]) { | |
340 | /* reuse an existing connection */ | |
341 | rxrpc_get_connection(server->fs_conn[nconn]); | |
342 | callslot->conn = server->fs_conn[nconn]; | |
343 | } | |
344 | else { | |
345 | /* create a new connection */ | |
346 | ret = rxrpc_create_connection(afs_transport, | |
347 | htons(7000), | |
348 | server->addr.s_addr, | |
349 | FS_SERVICE_ID, | |
350 | NULL, | |
351 | &server->fs_conn[nconn]); | |
352 | ||
353 | if (ret < 0) | |
354 | goto error_release_upw; | |
355 | ||
356 | callslot->conn = server->fs_conn[0]; | |
357 | rxrpc_get_connection(callslot->conn); | |
358 | } | |
359 | ||
360 | up_write(&server->sem); | |
361 | ||
362 | _leave(" = 0"); | |
363 | return 0; | |
364 | ||
365 | /* handle an error occurring */ | |
366 | error_release_upw: | |
367 | up_write(&server->sem); | |
368 | ||
369 | error_release: | |
370 | /* either release the callslot or pass it along to another deserving | |
371 | * task */ | |
372 | spin_lock(&server->fs_lock); | |
373 | ||
374 | if (nconn < 0) { | |
375 | /* no callslot allocated */ | |
376 | } | |
377 | else if (list_empty(&server->fs_callq)) { | |
378 | /* no one waiting */ | |
379 | server->fs_conn_cnt[nconn]++; | |
380 | spin_unlock(&server->fs_lock); | |
381 | } | |
382 | else { | |
383 | /* someone's waiting - dequeue them and wake them up */ | |
384 | pcallslot = list_entry(server->fs_callq.next, | |
385 | struct afs_server_callslot, link); | |
386 | list_del_init(&pcallslot->link); | |
387 | ||
388 | pcallslot->errno = server->fs_state; | |
389 | if (!pcallslot->errno) { | |
390 | /* pass them out callslot details */ | |
391 | callslot->conn = xchg(&pcallslot->conn, | |
392 | callslot->conn); | |
393 | pcallslot->nconn = nconn; | |
394 | callslot->nconn = nconn = -1; | |
395 | } | |
396 | pcallslot->ready = 1; | |
397 | wake_up_process(pcallslot->task); | |
398 | spin_unlock(&server->fs_lock); | |
399 | } | |
400 | ||
401 | rxrpc_put_connection(callslot->conn); | |
402 | callslot->conn = NULL; | |
403 | ||
404 | _leave(" = %d", ret); | |
405 | return ret; | |
406 | ||
407 | } /* end afs_server_request_callslot() */ | |
408 | ||
409 | /*****************************************************************************/ | |
410 | /* | |
411 | * release a callslot back to the server | |
412 | * - transfers the RxRPC connection to the next pending callslot if possible | |
413 | */ | |
414 | void afs_server_release_callslot(struct afs_server *server, | |
415 | struct afs_server_callslot *callslot) | |
416 | { | |
417 | struct afs_server_callslot *pcallslot; | |
418 | ||
419 | _enter("{ad=%08x,cnt=%u},{%d}", | |
420 | ntohl(server->addr.s_addr), | |
421 | server->fs_conn_cnt[callslot->nconn], | |
422 | callslot->nconn); | |
423 | ||
424 | BUG_ON(callslot->nconn < 0); | |
425 | ||
426 | spin_lock(&server->fs_lock); | |
427 | ||
428 | if (list_empty(&server->fs_callq)) { | |
429 | /* no one waiting */ | |
430 | server->fs_conn_cnt[callslot->nconn]++; | |
431 | spin_unlock(&server->fs_lock); | |
432 | } | |
433 | else { | |
434 | /* someone's waiting - dequeue them and wake them up */ | |
435 | pcallslot = list_entry(server->fs_callq.next, | |
436 | struct afs_server_callslot, link); | |
437 | list_del_init(&pcallslot->link); | |
438 | ||
439 | pcallslot->errno = server->fs_state; | |
440 | if (!pcallslot->errno) { | |
441 | /* pass them out callslot details */ | |
442 | callslot->conn = xchg(&pcallslot->conn, callslot->conn); | |
443 | pcallslot->nconn = callslot->nconn; | |
444 | callslot->nconn = -1; | |
445 | } | |
446 | ||
447 | pcallslot->ready = 1; | |
448 | wake_up_process(pcallslot->task); | |
449 | spin_unlock(&server->fs_lock); | |
450 | } | |
451 | ||
452 | rxrpc_put_connection(callslot->conn); | |
453 | ||
454 | _leave(""); | |
455 | } /* end afs_server_release_callslot() */ | |
456 | ||
457 | /*****************************************************************************/ | |
458 | /* | |
459 | * get a handle to a connection to the vlserver (volume location) on the | |
460 | * specified server | |
461 | */ | |
462 | int afs_server_get_vlconn(struct afs_server *server, | |
463 | struct rxrpc_connection **_conn) | |
464 | { | |
465 | struct rxrpc_connection *conn; | |
466 | int ret; | |
467 | ||
468 | _enter("%p,", server); | |
469 | ||
470 | ret = 0; | |
471 | conn = NULL; | |
472 | down_read(&server->sem); | |
473 | ||
474 | if (server->vlserver) { | |
475 | /* reuse an existing connection */ | |
476 | rxrpc_get_connection(server->vlserver); | |
477 | conn = server->vlserver; | |
478 | up_read(&server->sem); | |
479 | } | |
480 | else { | |
481 | /* create a new connection */ | |
482 | up_read(&server->sem); | |
483 | down_write(&server->sem); | |
484 | if (!server->vlserver) { | |
485 | ret = rxrpc_create_connection(afs_transport, | |
486 | htons(7003), | |
487 | server->addr.s_addr, | |
488 | VL_SERVICE_ID, | |
489 | NULL, | |
490 | &server->vlserver); | |
491 | } | |
492 | if (ret == 0) { | |
493 | rxrpc_get_connection(server->vlserver); | |
494 | conn = server->vlserver; | |
495 | } | |
496 | up_write(&server->sem); | |
497 | } | |
498 | ||
499 | *_conn = conn; | |
500 | _leave(" = %d", ret); | |
501 | return ret; | |
502 | } /* end afs_server_get_vlconn() */ |