server.c 18 KB

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  1. // SPDX-License-Identifier: GPL-2.0-or-later
  2. /* AFS server record management
  3. *
  4. * Copyright (C) 2002, 2007 Red Hat, Inc. All Rights Reserved.
  5. * Written by David Howells ([email protected])
  6. */
  7. #include <linux/sched.h>
  8. #include <linux/slab.h>
  9. #include "afs_fs.h"
  10. #include "internal.h"
  11. #include "protocol_yfs.h"
  12. static unsigned afs_server_gc_delay = 10; /* Server record timeout in seconds */
  13. static atomic_t afs_server_debug_id;
  14. static struct afs_server *afs_maybe_use_server(struct afs_server *,
  15. enum afs_server_trace);
  16. static void __afs_put_server(struct afs_net *, struct afs_server *);
  17. /*
  18. * Find a server by one of its addresses.
  19. */
  20. struct afs_server *afs_find_server(struct afs_net *net,
  21. const struct sockaddr_rxrpc *srx)
  22. {
  23. const struct afs_addr_list *alist;
  24. struct afs_server *server = NULL;
  25. unsigned int i;
  26. int seq = 0, diff;
  27. rcu_read_lock();
  28. do {
  29. if (server)
  30. afs_unuse_server_notime(net, server, afs_server_trace_put_find_rsq);
  31. server = NULL;
  32. read_seqbegin_or_lock(&net->fs_addr_lock, &seq);
  33. if (srx->transport.family == AF_INET6) {
  34. const struct sockaddr_in6 *a = &srx->transport.sin6, *b;
  35. hlist_for_each_entry_rcu(server, &net->fs_addresses6, addr6_link) {
  36. alist = rcu_dereference(server->addresses);
  37. for (i = alist->nr_ipv4; i < alist->nr_addrs; i++) {
  38. b = &alist->addrs[i].transport.sin6;
  39. diff = ((u16 __force)a->sin6_port -
  40. (u16 __force)b->sin6_port);
  41. if (diff == 0)
  42. diff = memcmp(&a->sin6_addr,
  43. &b->sin6_addr,
  44. sizeof(struct in6_addr));
  45. if (diff == 0)
  46. goto found;
  47. }
  48. }
  49. } else {
  50. const struct sockaddr_in *a = &srx->transport.sin, *b;
  51. hlist_for_each_entry_rcu(server, &net->fs_addresses4, addr4_link) {
  52. alist = rcu_dereference(server->addresses);
  53. for (i = 0; i < alist->nr_ipv4; i++) {
  54. b = &alist->addrs[i].transport.sin;
  55. diff = ((u16 __force)a->sin_port -
  56. (u16 __force)b->sin_port);
  57. if (diff == 0)
  58. diff = ((u32 __force)a->sin_addr.s_addr -
  59. (u32 __force)b->sin_addr.s_addr);
  60. if (diff == 0)
  61. goto found;
  62. }
  63. }
  64. }
  65. server = NULL;
  66. continue;
  67. found:
  68. server = afs_maybe_use_server(server, afs_server_trace_get_by_addr);
  69. } while (need_seqretry(&net->fs_addr_lock, seq));
  70. done_seqretry(&net->fs_addr_lock, seq);
  71. rcu_read_unlock();
  72. return server;
  73. }
  74. /*
  75. * Look up a server by its UUID and mark it active.
  76. */
  77. struct afs_server *afs_find_server_by_uuid(struct afs_net *net, const uuid_t *uuid)
  78. {
  79. struct afs_server *server = NULL;
  80. struct rb_node *p;
  81. int diff, seq = 0;
  82. _enter("%pU", uuid);
  83. do {
  84. /* Unfortunately, rbtree walking doesn't give reliable results
  85. * under just the RCU read lock, so we have to check for
  86. * changes.
  87. */
  88. if (server)
  89. afs_unuse_server(net, server, afs_server_trace_put_uuid_rsq);
  90. server = NULL;
  91. read_seqbegin_or_lock(&net->fs_lock, &seq);
  92. p = net->fs_servers.rb_node;
  93. while (p) {
  94. server = rb_entry(p, struct afs_server, uuid_rb);
  95. diff = memcmp(uuid, &server->uuid, sizeof(*uuid));
  96. if (diff < 0) {
  97. p = p->rb_left;
  98. } else if (diff > 0) {
  99. p = p->rb_right;
  100. } else {
  101. afs_use_server(server, afs_server_trace_get_by_uuid);
  102. break;
  103. }
  104. server = NULL;
  105. }
  106. } while (need_seqretry(&net->fs_lock, seq));
  107. done_seqretry(&net->fs_lock, seq);
  108. _leave(" = %p", server);
  109. return server;
  110. }
  111. /*
  112. * Install a server record in the namespace tree. If there's a clash, we stick
  113. * it into a list anchored on whichever afs_server struct is actually in the
  114. * tree.
  115. */
  116. static struct afs_server *afs_install_server(struct afs_cell *cell,
  117. struct afs_server *candidate)
  118. {
  119. const struct afs_addr_list *alist;
  120. struct afs_server *server, *next;
  121. struct afs_net *net = cell->net;
  122. struct rb_node **pp, *p;
  123. int diff;
  124. _enter("%p", candidate);
  125. write_seqlock(&net->fs_lock);
  126. /* Firstly install the server in the UUID lookup tree */
  127. pp = &net->fs_servers.rb_node;
  128. p = NULL;
  129. while (*pp) {
  130. p = *pp;
  131. _debug("- consider %p", p);
  132. server = rb_entry(p, struct afs_server, uuid_rb);
  133. diff = memcmp(&candidate->uuid, &server->uuid, sizeof(uuid_t));
  134. if (diff < 0) {
  135. pp = &(*pp)->rb_left;
  136. } else if (diff > 0) {
  137. pp = &(*pp)->rb_right;
  138. } else {
  139. if (server->cell == cell)
  140. goto exists;
  141. /* We have the same UUID representing servers in
  142. * different cells. Append the new server to the list.
  143. */
  144. for (;;) {
  145. next = rcu_dereference_protected(
  146. server->uuid_next,
  147. lockdep_is_held(&net->fs_lock.lock));
  148. if (!next)
  149. break;
  150. server = next;
  151. }
  152. rcu_assign_pointer(server->uuid_next, candidate);
  153. candidate->uuid_prev = server;
  154. server = candidate;
  155. goto added_dup;
  156. }
  157. }
  158. server = candidate;
  159. rb_link_node(&server->uuid_rb, p, pp);
  160. rb_insert_color(&server->uuid_rb, &net->fs_servers);
  161. hlist_add_head_rcu(&server->proc_link, &net->fs_proc);
  162. added_dup:
  163. write_seqlock(&net->fs_addr_lock);
  164. alist = rcu_dereference_protected(server->addresses,
  165. lockdep_is_held(&net->fs_addr_lock.lock));
  166. /* Secondly, if the server has any IPv4 and/or IPv6 addresses, install
  167. * it in the IPv4 and/or IPv6 reverse-map lists.
  168. *
  169. * TODO: For speed we want to use something other than a flat list
  170. * here; even sorting the list in terms of lowest address would help a
  171. * bit, but anything we might want to do gets messy and memory
  172. * intensive.
  173. */
  174. if (alist->nr_ipv4 > 0)
  175. hlist_add_head_rcu(&server->addr4_link, &net->fs_addresses4);
  176. if (alist->nr_addrs > alist->nr_ipv4)
  177. hlist_add_head_rcu(&server->addr6_link, &net->fs_addresses6);
  178. write_sequnlock(&net->fs_addr_lock);
  179. exists:
  180. afs_get_server(server, afs_server_trace_get_install);
  181. write_sequnlock(&net->fs_lock);
  182. return server;
  183. }
  184. /*
  185. * Allocate a new server record and mark it active.
  186. */
  187. static struct afs_server *afs_alloc_server(struct afs_cell *cell,
  188. const uuid_t *uuid,
  189. struct afs_addr_list *alist)
  190. {
  191. struct afs_server *server;
  192. struct afs_net *net = cell->net;
  193. _enter("");
  194. server = kzalloc(sizeof(struct afs_server), GFP_KERNEL);
  195. if (!server)
  196. goto enomem;
  197. refcount_set(&server->ref, 1);
  198. atomic_set(&server->active, 1);
  199. server->debug_id = atomic_inc_return(&afs_server_debug_id);
  200. RCU_INIT_POINTER(server->addresses, alist);
  201. server->addr_version = alist->version;
  202. server->uuid = *uuid;
  203. rwlock_init(&server->fs_lock);
  204. INIT_WORK(&server->initcb_work, afs_server_init_callback_work);
  205. init_waitqueue_head(&server->probe_wq);
  206. INIT_LIST_HEAD(&server->probe_link);
  207. spin_lock_init(&server->probe_lock);
  208. server->cell = cell;
  209. server->rtt = UINT_MAX;
  210. afs_inc_servers_outstanding(net);
  211. trace_afs_server(server->debug_id, 1, 1, afs_server_trace_alloc);
  212. _leave(" = %p", server);
  213. return server;
  214. enomem:
  215. _leave(" = NULL [nomem]");
  216. return NULL;
  217. }
  218. /*
  219. * Look up an address record for a server
  220. */
  221. static struct afs_addr_list *afs_vl_lookup_addrs(struct afs_cell *cell,
  222. struct key *key, const uuid_t *uuid)
  223. {
  224. struct afs_vl_cursor vc;
  225. struct afs_addr_list *alist = NULL;
  226. int ret;
  227. ret = -ERESTARTSYS;
  228. if (afs_begin_vlserver_operation(&vc, cell, key)) {
  229. while (afs_select_vlserver(&vc)) {
  230. if (test_bit(AFS_VLSERVER_FL_IS_YFS, &vc.server->flags))
  231. alist = afs_yfsvl_get_endpoints(&vc, uuid);
  232. else
  233. alist = afs_vl_get_addrs_u(&vc, uuid);
  234. }
  235. ret = afs_end_vlserver_operation(&vc);
  236. }
  237. return ret < 0 ? ERR_PTR(ret) : alist;
  238. }
  239. /*
  240. * Get or create a fileserver record.
  241. */
  242. struct afs_server *afs_lookup_server(struct afs_cell *cell, struct key *key,
  243. const uuid_t *uuid, u32 addr_version)
  244. {
  245. struct afs_addr_list *alist;
  246. struct afs_server *server, *candidate;
  247. _enter("%p,%pU", cell->net, uuid);
  248. server = afs_find_server_by_uuid(cell->net, uuid);
  249. if (server) {
  250. if (server->addr_version != addr_version)
  251. set_bit(AFS_SERVER_FL_NEEDS_UPDATE, &server->flags);
  252. return server;
  253. }
  254. alist = afs_vl_lookup_addrs(cell, key, uuid);
  255. if (IS_ERR(alist))
  256. return ERR_CAST(alist);
  257. candidate = afs_alloc_server(cell, uuid, alist);
  258. if (!candidate) {
  259. afs_put_addrlist(alist);
  260. return ERR_PTR(-ENOMEM);
  261. }
  262. server = afs_install_server(cell, candidate);
  263. if (server != candidate) {
  264. afs_put_addrlist(alist);
  265. kfree(candidate);
  266. } else {
  267. /* Immediately dispatch an asynchronous probe to each interface
  268. * on the fileserver. This will make sure the repeat-probing
  269. * service is started.
  270. */
  271. afs_fs_probe_fileserver(cell->net, server, key, true);
  272. }
  273. return server;
  274. }
  275. /*
  276. * Set the server timer to fire after a given delay, assuming it's not already
  277. * set for an earlier time.
  278. */
  279. static void afs_set_server_timer(struct afs_net *net, time64_t delay)
  280. {
  281. if (net->live) {
  282. afs_inc_servers_outstanding(net);
  283. if (timer_reduce(&net->fs_timer, jiffies + delay * HZ))
  284. afs_dec_servers_outstanding(net);
  285. }
  286. }
  287. /*
  288. * Server management timer. We have an increment on fs_outstanding that we
  289. * need to pass along to the work item.
  290. */
  291. void afs_servers_timer(struct timer_list *timer)
  292. {
  293. struct afs_net *net = container_of(timer, struct afs_net, fs_timer);
  294. _enter("");
  295. if (!queue_work(afs_wq, &net->fs_manager))
  296. afs_dec_servers_outstanding(net);
  297. }
  298. /*
  299. * Get a reference on a server object.
  300. */
  301. struct afs_server *afs_get_server(struct afs_server *server,
  302. enum afs_server_trace reason)
  303. {
  304. unsigned int a;
  305. int r;
  306. __refcount_inc(&server->ref, &r);
  307. a = atomic_read(&server->active);
  308. trace_afs_server(server->debug_id, r + 1, a, reason);
  309. return server;
  310. }
  311. /*
  312. * Try to get a reference on a server object.
  313. */
  314. static struct afs_server *afs_maybe_use_server(struct afs_server *server,
  315. enum afs_server_trace reason)
  316. {
  317. unsigned int a;
  318. int r;
  319. if (!__refcount_inc_not_zero(&server->ref, &r))
  320. return NULL;
  321. a = atomic_inc_return(&server->active);
  322. trace_afs_server(server->debug_id, r + 1, a, reason);
  323. return server;
  324. }
  325. /*
  326. * Get an active count on a server object.
  327. */
  328. struct afs_server *afs_use_server(struct afs_server *server, enum afs_server_trace reason)
  329. {
  330. unsigned int a;
  331. int r;
  332. __refcount_inc(&server->ref, &r);
  333. a = atomic_inc_return(&server->active);
  334. trace_afs_server(server->debug_id, r + 1, a, reason);
  335. return server;
  336. }
  337. /*
  338. * Release a reference on a server record.
  339. */
  340. void afs_put_server(struct afs_net *net, struct afs_server *server,
  341. enum afs_server_trace reason)
  342. {
  343. unsigned int a, debug_id = server->debug_id;
  344. bool zero;
  345. int r;
  346. if (!server)
  347. return;
  348. a = atomic_read(&server->active);
  349. zero = __refcount_dec_and_test(&server->ref, &r);
  350. trace_afs_server(debug_id, r - 1, a, reason);
  351. if (unlikely(zero))
  352. __afs_put_server(net, server);
  353. }
  354. /*
  355. * Drop an active count on a server object without updating the last-unused
  356. * time.
  357. */
  358. void afs_unuse_server_notime(struct afs_net *net, struct afs_server *server,
  359. enum afs_server_trace reason)
  360. {
  361. if (server) {
  362. unsigned int active = atomic_dec_return(&server->active);
  363. if (active == 0)
  364. afs_set_server_timer(net, afs_server_gc_delay);
  365. afs_put_server(net, server, reason);
  366. }
  367. }
  368. /*
  369. * Drop an active count on a server object.
  370. */
  371. void afs_unuse_server(struct afs_net *net, struct afs_server *server,
  372. enum afs_server_trace reason)
  373. {
  374. if (server) {
  375. server->unuse_time = ktime_get_real_seconds();
  376. afs_unuse_server_notime(net, server, reason);
  377. }
  378. }
  379. static void afs_server_rcu(struct rcu_head *rcu)
  380. {
  381. struct afs_server *server = container_of(rcu, struct afs_server, rcu);
  382. trace_afs_server(server->debug_id, refcount_read(&server->ref),
  383. atomic_read(&server->active), afs_server_trace_free);
  384. afs_put_addrlist(rcu_access_pointer(server->addresses));
  385. kfree(server);
  386. }
  387. static void __afs_put_server(struct afs_net *net, struct afs_server *server)
  388. {
  389. call_rcu(&server->rcu, afs_server_rcu);
  390. afs_dec_servers_outstanding(net);
  391. }
  392. static void afs_give_up_callbacks(struct afs_net *net, struct afs_server *server)
  393. {
  394. struct afs_addr_list *alist = rcu_access_pointer(server->addresses);
  395. struct afs_addr_cursor ac = {
  396. .alist = alist,
  397. .index = alist->preferred,
  398. .error = 0,
  399. };
  400. afs_fs_give_up_all_callbacks(net, server, &ac, NULL);
  401. }
  402. /*
  403. * destroy a dead server
  404. */
  405. static void afs_destroy_server(struct afs_net *net, struct afs_server *server)
  406. {
  407. if (test_bit(AFS_SERVER_FL_MAY_HAVE_CB, &server->flags))
  408. afs_give_up_callbacks(net, server);
  409. flush_work(&server->initcb_work);
  410. afs_put_server(net, server, afs_server_trace_destroy);
  411. }
  412. /*
  413. * Garbage collect any expired servers.
  414. */
  415. static void afs_gc_servers(struct afs_net *net, struct afs_server *gc_list)
  416. {
  417. struct afs_server *server, *next, *prev;
  418. int active;
  419. while ((server = gc_list)) {
  420. gc_list = server->gc_next;
  421. write_seqlock(&net->fs_lock);
  422. active = atomic_read(&server->active);
  423. if (active == 0) {
  424. trace_afs_server(server->debug_id, refcount_read(&server->ref),
  425. active, afs_server_trace_gc);
  426. next = rcu_dereference_protected(
  427. server->uuid_next, lockdep_is_held(&net->fs_lock.lock));
  428. prev = server->uuid_prev;
  429. if (!prev) {
  430. /* The one at the front is in the tree */
  431. if (!next) {
  432. rb_erase(&server->uuid_rb, &net->fs_servers);
  433. } else {
  434. rb_replace_node_rcu(&server->uuid_rb,
  435. &next->uuid_rb,
  436. &net->fs_servers);
  437. next->uuid_prev = NULL;
  438. }
  439. } else {
  440. /* This server is not at the front */
  441. rcu_assign_pointer(prev->uuid_next, next);
  442. if (next)
  443. next->uuid_prev = prev;
  444. }
  445. list_del(&server->probe_link);
  446. hlist_del_rcu(&server->proc_link);
  447. if (!hlist_unhashed(&server->addr4_link))
  448. hlist_del_rcu(&server->addr4_link);
  449. if (!hlist_unhashed(&server->addr6_link))
  450. hlist_del_rcu(&server->addr6_link);
  451. }
  452. write_sequnlock(&net->fs_lock);
  453. if (active == 0)
  454. afs_destroy_server(net, server);
  455. }
  456. }
  457. /*
  458. * Manage the records of servers known to be within a network namespace. This
  459. * includes garbage collecting unused servers.
  460. *
  461. * Note also that we were given an increment on net->servers_outstanding by
  462. * whoever queued us that we need to deal with before returning.
  463. */
  464. void afs_manage_servers(struct work_struct *work)
  465. {
  466. struct afs_net *net = container_of(work, struct afs_net, fs_manager);
  467. struct afs_server *gc_list = NULL;
  468. struct rb_node *cursor;
  469. time64_t now = ktime_get_real_seconds(), next_manage = TIME64_MAX;
  470. bool purging = !net->live;
  471. _enter("");
  472. /* Trawl the server list looking for servers that have expired from
  473. * lack of use.
  474. */
  475. read_seqlock_excl(&net->fs_lock);
  476. for (cursor = rb_first(&net->fs_servers); cursor; cursor = rb_next(cursor)) {
  477. struct afs_server *server =
  478. rb_entry(cursor, struct afs_server, uuid_rb);
  479. int active = atomic_read(&server->active);
  480. _debug("manage %pU %u", &server->uuid, active);
  481. if (purging) {
  482. trace_afs_server(server->debug_id, refcount_read(&server->ref),
  483. active, afs_server_trace_purging);
  484. if (active != 0)
  485. pr_notice("Can't purge s=%08x\n", server->debug_id);
  486. }
  487. if (active == 0) {
  488. time64_t expire_at = server->unuse_time;
  489. if (!test_bit(AFS_SERVER_FL_VL_FAIL, &server->flags) &&
  490. !test_bit(AFS_SERVER_FL_NOT_FOUND, &server->flags))
  491. expire_at += afs_server_gc_delay;
  492. if (purging || expire_at <= now) {
  493. server->gc_next = gc_list;
  494. gc_list = server;
  495. } else if (expire_at < next_manage) {
  496. next_manage = expire_at;
  497. }
  498. }
  499. }
  500. read_sequnlock_excl(&net->fs_lock);
  501. /* Update the timer on the way out. We have to pass an increment on
  502. * servers_outstanding in the namespace that we are in to the timer or
  503. * the work scheduler.
  504. */
  505. if (!purging && next_manage < TIME64_MAX) {
  506. now = ktime_get_real_seconds();
  507. if (next_manage - now <= 0) {
  508. if (queue_work(afs_wq, &net->fs_manager))
  509. afs_inc_servers_outstanding(net);
  510. } else {
  511. afs_set_server_timer(net, next_manage - now);
  512. }
  513. }
  514. afs_gc_servers(net, gc_list);
  515. afs_dec_servers_outstanding(net);
  516. _leave(" [%d]", atomic_read(&net->servers_outstanding));
  517. }
  518. static void afs_queue_server_manager(struct afs_net *net)
  519. {
  520. afs_inc_servers_outstanding(net);
  521. if (!queue_work(afs_wq, &net->fs_manager))
  522. afs_dec_servers_outstanding(net);
  523. }
  524. /*
  525. * Purge list of servers.
  526. */
  527. void afs_purge_servers(struct afs_net *net)
  528. {
  529. _enter("");
  530. if (del_timer_sync(&net->fs_timer))
  531. afs_dec_servers_outstanding(net);
  532. afs_queue_server_manager(net);
  533. _debug("wait");
  534. atomic_dec(&net->servers_outstanding);
  535. wait_var_event(&net->servers_outstanding,
  536. !atomic_read(&net->servers_outstanding));
  537. _leave("");
  538. }
  539. /*
  540. * Get an update for a server's address list.
  541. */
  542. static noinline bool afs_update_server_record(struct afs_operation *op,
  543. struct afs_server *server)
  544. {
  545. struct afs_addr_list *alist, *discard;
  546. _enter("");
  547. trace_afs_server(server->debug_id, refcount_read(&server->ref),
  548. atomic_read(&server->active),
  549. afs_server_trace_update);
  550. alist = afs_vl_lookup_addrs(op->volume->cell, op->key, &server->uuid);
  551. if (IS_ERR(alist)) {
  552. if ((PTR_ERR(alist) == -ERESTARTSYS ||
  553. PTR_ERR(alist) == -EINTR) &&
  554. (op->flags & AFS_OPERATION_UNINTR) &&
  555. server->addresses) {
  556. _leave(" = t [intr]");
  557. return true;
  558. }
  559. op->error = PTR_ERR(alist);
  560. _leave(" = f [%d]", op->error);
  561. return false;
  562. }
  563. discard = alist;
  564. if (server->addr_version != alist->version) {
  565. write_lock(&server->fs_lock);
  566. discard = rcu_dereference_protected(server->addresses,
  567. lockdep_is_held(&server->fs_lock));
  568. rcu_assign_pointer(server->addresses, alist);
  569. server->addr_version = alist->version;
  570. write_unlock(&server->fs_lock);
  571. }
  572. afs_put_addrlist(discard);
  573. _leave(" = t");
  574. return true;
  575. }
  576. /*
  577. * See if a server's address list needs updating.
  578. */
  579. bool afs_check_server_record(struct afs_operation *op, struct afs_server *server)
  580. {
  581. bool success;
  582. int ret, retries = 0;
  583. _enter("");
  584. ASSERT(server);
  585. retry:
  586. if (test_bit(AFS_SERVER_FL_UPDATING, &server->flags))
  587. goto wait;
  588. if (test_bit(AFS_SERVER_FL_NEEDS_UPDATE, &server->flags))
  589. goto update;
  590. _leave(" = t [good]");
  591. return true;
  592. update:
  593. if (!test_and_set_bit_lock(AFS_SERVER_FL_UPDATING, &server->flags)) {
  594. clear_bit(AFS_SERVER_FL_NEEDS_UPDATE, &server->flags);
  595. success = afs_update_server_record(op, server);
  596. clear_bit_unlock(AFS_SERVER_FL_UPDATING, &server->flags);
  597. wake_up_bit(&server->flags, AFS_SERVER_FL_UPDATING);
  598. _leave(" = %d", success);
  599. return success;
  600. }
  601. wait:
  602. ret = wait_on_bit(&server->flags, AFS_SERVER_FL_UPDATING,
  603. (op->flags & AFS_OPERATION_UNINTR) ?
  604. TASK_UNINTERRUPTIBLE : TASK_INTERRUPTIBLE);
  605. if (ret == -ERESTARTSYS) {
  606. op->error = ret;
  607. _leave(" = f [intr]");
  608. return false;
  609. }
  610. retries++;
  611. if (retries == 4) {
  612. _leave(" = f [stale]");
  613. ret = -ESTALE;
  614. return false;
  615. }
  616. goto retry;
  617. }