1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* AFS cell and server record management
3 *
4 * Copyright (C) 2002, 2017 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells (dhowells@redhat.com)
6 */
7
8 #include <linux/slab.h>
9 #include <linux/key.h>
10 #include <linux/ctype.h>
11 #include <linux/dns_resolver.h>
12 #include <linux/sched.h>
13 #include <linux/inet.h>
14 #include <linux/namei.h>
15 #include <keys/rxrpc-type.h>
16 #include "internal.h"
17
18 static unsigned __read_mostly afs_cell_gc_delay = 10;
19 static unsigned __read_mostly afs_cell_min_ttl = 10 * 60;
20 static unsigned __read_mostly afs_cell_max_ttl = 24 * 60 * 60;
21 static atomic_t cell_debug_id;
22
23 static void afs_queue_cell_manager(struct afs_net *);
24 static void afs_manage_cell_work(struct work_struct *);
25
26 static void afs_dec_cells_outstanding(struct afs_net *net)
27 {
28 if (atomic_dec_and_test(&net->cells_outstanding))
29 wake_up_var(&net->cells_outstanding);
30 }
31
32 /*
33 * Set the cell timer to fire after a given delay, assuming it's not already
34 * set for an earlier time.
35 */
36 static void afs_set_cell_timer(struct afs_net *net, time64_t delay)
37 {
38 if (net->live) {
39 atomic_inc(&net->cells_outstanding);
40 if (timer_reduce(&net->cells_timer, jiffies + delay * HZ))
41 afs_dec_cells_outstanding(net);
42 } else {
43 afs_queue_cell_manager(net);
44 }
45 }
46
47 /*
48 * Look up and get an activation reference on a cell record. The caller must
49 * hold net->cells_lock at least read-locked.
50 */
51 static struct afs_cell *afs_find_cell_locked(struct afs_net *net,
52 const char *name, unsigned int namesz,
53 enum afs_cell_trace reason)
54 {
55 struct afs_cell *cell = NULL;
56 struct rb_node *p;
57 int n;
58
59 _enter("%*.*s", namesz, namesz, name);
60
61 if (name && namesz == 0)
62 return ERR_PTR(-EINVAL);
63 if (namesz > AFS_MAXCELLNAME)
64 return ERR_PTR(-ENAMETOOLONG);
65
66 if (!name) {
67 cell = net->ws_cell;
68 if (!cell)
69 return ERR_PTR(-EDESTADDRREQ);
70 goto found;
71 }
72
73 p = net->cells.rb_node;
74 while (p) {
75 cell = rb_entry(p, struct afs_cell, net_node);
76
77 n = strncasecmp(cell->name, name,
78 min_t(size_t, cell->name_len, namesz));
79 if (n == 0)
80 n = cell->name_len - namesz;
81 if (n < 0)
82 p = p->rb_left;
83 else if (n > 0)
84 p = p->rb_right;
85 else
86 goto found;
87 }
88
89 return ERR_PTR(-ENOENT);
90
91 found:
92 return afs_use_cell(cell, reason);
93 }
94
95 /*
96 * Look up and get an activation reference on a cell record.
97 */
98 struct afs_cell *afs_find_cell(struct afs_net *net,
99 const char *name, unsigned int namesz,
100 enum afs_cell_trace reason)
101 {
102 struct afs_cell *cell;
103
104 down_read(&net->cells_lock);
105 cell = afs_find_cell_locked(net, name, namesz, reason);
106 up_read(&net->cells_lock);
107 return cell;
108 }
109
110 /*
111 * Set up a cell record and fill in its name, VL server address list and
112 * allocate an anonymous key
113 */
114 static struct afs_cell *afs_alloc_cell(struct afs_net *net,
115 const char *name, unsigned int namelen,
116 const char *addresses)
117 {
118 struct afs_vlserver_list *vllist;
119 struct afs_cell *cell;
120 int i, ret;
121
122 ASSERT(name);
123 if (namelen == 0)
124 return ERR_PTR(-EINVAL);
125 if (namelen > AFS_MAXCELLNAME) {
126 _leave(" = -ENAMETOOLONG");
127 return ERR_PTR(-ENAMETOOLONG);
128 }
129
130 /* Prohibit cell names that contain unprintable chars, '/' and '@' or
131 * that begin with a dot. This also precludes "@cell".
132 */
133 if (name[0] == '.')
134 return ERR_PTR(-EINVAL);
135 for (i = 0; i < namelen; i++) {
136 char ch = name[i];
137 if (!isprint(ch) || ch == '/' || ch == '@')
138 return ERR_PTR(-EINVAL);
139 }
140
141 _enter("%*.*s,%s", namelen, namelen, name, addresses);
142
143 cell = kzalloc(sizeof(struct afs_cell), GFP_KERNEL);
144 if (!cell) {
145 _leave(" = -ENOMEM");
146 return ERR_PTR(-ENOMEM);
147 }
148
149 cell->name = kmalloc(namelen + 1, GFP_KERNEL);
150 if (!cell->name) {
151 kfree(cell);
152 return ERR_PTR(-ENOMEM);
153 }
154
155 cell->net = net;
156 cell->name_len = namelen;
157 for (i = 0; i < namelen; i++)
158 cell->name[i] = tolower(name[i]);
159 cell->name[i] = 0;
160
161 refcount_set(&cell->ref, 1);
162 atomic_set(&cell->active, 0);
163 INIT_WORK(&cell->manager, afs_manage_cell_work);
164 init_rwsem(&cell->vs_lock);
165 cell->volumes = RB_ROOT;
166 INIT_HLIST_HEAD(&cell->proc_volumes);
167 seqlock_init(&cell->volume_lock);
168 cell->fs_servers = RB_ROOT;
169 seqlock_init(&cell->fs_lock);
170 rwlock_init(&cell->vl_servers_lock);
171 cell->flags = (1 << AFS_CELL_FL_CHECK_ALIAS);
172
173 /* Provide a VL server list, filling it in if we were given a list of
174 * addresses to use.
175 */
176 if (addresses) {
177 vllist = afs_parse_text_addrs(net,
178 addresses, strlen(addresses), ':',
179 VL_SERVICE, AFS_VL_PORT);
180 if (IS_ERR(vllist)) {
181 ret = PTR_ERR(vllist);
182 goto parse_failed;
183 }
184
185 vllist->source = DNS_RECORD_FROM_CONFIG;
186 vllist->status = DNS_LOOKUP_NOT_DONE;
187 cell->dns_expiry = TIME64_MAX;
188 } else {
189 ret = -ENOMEM;
190 vllist = afs_alloc_vlserver_list(0);
191 if (!vllist)
192 goto error;
193 vllist->source = DNS_RECORD_UNAVAILABLE;
194 vllist->status = DNS_LOOKUP_NOT_DONE;
195 cell->dns_expiry = ktime_get_real_seconds();
196 }
197
198 rcu_assign_pointer(cell->vl_servers, vllist);
199
200 cell->dns_source = vllist->source;
201 cell->dns_status = vllist->status;
202 smp_store_release(&cell->dns_lookup_count, 1); /* vs source/status */
203 atomic_inc(&net->cells_outstanding);
204 cell->debug_id = atomic_inc_return(&cell_debug_id);
205 trace_afs_cell(cell->debug_id, 1, 0, afs_cell_trace_alloc);
206
207 _leave(" = %p", cell);
208 return cell;
209
210 parse_failed:
211 if (ret == -EINVAL)
212 printk(KERN_ERR "kAFS: bad VL server IP address\n");
213 error:
214 kfree(cell->name);
215 kfree(cell);
216 _leave(" = %d", ret);
217 return ERR_PTR(ret);
218 }
219
220 /*
221 * afs_lookup_cell - Look up or create a cell record.
222 * @net: The network namespace
223 * @name: The name of the cell.
224 * @namesz: The strlen of the cell name.
225 * @vllist: A colon/comma separated list of numeric IP addresses or NULL.
226 * @excl: T if an error should be given if the cell name already exists.
227 *
228 * Look up a cell record by name and query the DNS for VL server addresses if
229 * needed. Note that that actual DNS query is punted off to the manager thread
230 * so that this function can return immediately if interrupted whilst allowing
231 * cell records to be shared even if not yet fully constructed.
232 */
233 struct afs_cell *afs_lookup_cell(struct afs_net *net,
234 const char *name, unsigned int namesz,
235 const char *vllist, bool excl)
236 {
237 struct afs_cell *cell, *candidate, *cursor;
238 struct rb_node *parent, **pp;
239 enum afs_cell_state state;
240 int ret, n;
241
242 _enter("%s,%s", name, vllist);
243
244 if (!excl) {
245 cell = afs_find_cell(net, name, namesz, afs_cell_trace_use_lookup);
246 if (!IS_ERR(cell))
247 goto wait_for_cell;
248 }
249
250 /* Assume we're probably going to create a cell and preallocate and
251 * mostly set up a candidate record. We can then use this to stash the
252 * name, the net namespace and VL server addresses.
253 *
254 * We also want to do this before we hold any locks as it may involve
255 * upcalling to userspace to make DNS queries.
256 */
257 candidate = afs_alloc_cell(net, name, namesz, vllist);
258 if (IS_ERR(candidate)) {
259 _leave(" = %ld", PTR_ERR(candidate));
260 return candidate;
261 }
262
263 /* Find the insertion point and check to see if someone else added a
264 * cell whilst we were allocating.
265 */
266 down_write(&net->cells_lock);
267
268 pp = &net->cells.rb_node;
269 parent = NULL;
270 while (*pp) {
271 parent = *pp;
272 cursor = rb_entry(parent, struct afs_cell, net_node);
273
274 n = strncasecmp(cursor->name, name,
275 min_t(size_t, cursor->name_len, namesz));
276 if (n == 0)
277 n = cursor->name_len - namesz;
278 if (n < 0)
279 pp = &(*pp)->rb_left;
280 else if (n > 0)
281 pp = &(*pp)->rb_right;
282 else
283 goto cell_already_exists;
284 }
285
286 cell = candidate;
287 candidate = NULL;
288 atomic_set(&cell->active, 2);
289 trace_afs_cell(cell->debug_id, refcount_read(&cell->ref), 2, afs_cell_trace_insert);
290 rb_link_node_rcu(&cell->net_node, parent, pp);
291 rb_insert_color(&cell->net_node, &net->cells);
292 up_write(&net->cells_lock);
293
294 afs_queue_cell(cell, afs_cell_trace_get_queue_new);
295
296 wait_for_cell:
297 trace_afs_cell(cell->debug_id, refcount_read(&cell->ref), atomic_read(&cell->active),
298 afs_cell_trace_wait);
299 _debug("wait_for_cell");
300 wait_var_event(&cell->state,
301 ({
302 state = smp_load_acquire(&cell->state); /* vs error */
303 state == AFS_CELL_ACTIVE || state == AFS_CELL_REMOVED;
304 }));
305
306 /* Check the state obtained from the wait check. */
307 if (state == AFS_CELL_REMOVED) {
308 ret = cell->error;
309 goto error;
310 }
311
312 _leave(" = %p [cell]", cell);
313 return cell;
314
315 cell_already_exists:
316 _debug("cell exists");
317 cell = cursor;
318 if (excl) {
319 ret = -EEXIST;
320 } else {
321 afs_use_cell(cursor, afs_cell_trace_use_lookup);
322 ret = 0;
323 }
324 up_write(&net->cells_lock);
325 if (candidate)
326 afs_put_cell(candidate, afs_cell_trace_put_candidate);
327 if (ret == 0)
328 goto wait_for_cell;
329 goto error_noput;
330 error:
331 afs_unuse_cell(net, cell, afs_cell_trace_unuse_lookup);
332 error_noput:
333 _leave(" = %d [error]", ret);
334 return ERR_PTR(ret);
335 }
336
337 /*
338 * set the root cell information
339 * - can be called with a module parameter string
340 * - can be called from a write to /proc/fs/afs/rootcell
341 */
342 int afs_cell_init(struct afs_net *net, const char *rootcell)
343 {
344 struct afs_cell *old_root, *new_root;
345 const char *cp, *vllist;
346 size_t len;
347
348 _enter("");
349
350 if (!rootcell) {
351 /* module is loaded with no parameters, or built statically.
352 * - in the future we might initialize cell DB here.
353 */
354 _leave(" = 0 [no root]");
355 return 0;
356 }
357
358 cp = strchr(rootcell, ':');
359 if (!cp) {
360 _debug("kAFS: no VL server IP addresses specified");
361 vllist = NULL;
362 len = strlen(rootcell);
363 } else {
364 vllist = cp + 1;
365 len = cp - rootcell;
366 }
367
368 /* allocate a cell record for the root cell */
369 new_root = afs_lookup_cell(net, rootcell, len, vllist, false);
370 if (IS_ERR(new_root)) {
371 _leave(" = %ld", PTR_ERR(new_root));
372 return PTR_ERR(new_root);
373 }
374
375 if (!test_and_set_bit(AFS_CELL_FL_NO_GC, &new_root->flags))
376 afs_use_cell(new_root, afs_cell_trace_use_pin);
377
378 /* install the new cell */
379 down_write(&net->cells_lock);
380 afs_see_cell(new_root, afs_cell_trace_see_ws);
381 old_root = net->ws_cell;
382 net->ws_cell = new_root;
383 up_write(&net->cells_lock);
384
385 afs_unuse_cell(net, old_root, afs_cell_trace_unuse_ws);
386 _leave(" = 0");
387 return 0;
388 }
389
390 /*
391 * Update a cell's VL server address list from the DNS.
392 */
393 static int afs_update_cell(struct afs_cell *cell)
394 {
395 struct afs_vlserver_list *vllist, *old = NULL, *p;
396 unsigned int min_ttl = READ_ONCE(afs_cell_min_ttl);
397 unsigned int max_ttl = READ_ONCE(afs_cell_max_ttl);
398 time64_t now, expiry = 0;
399 int ret = 0;
400
401 _enter("%s", cell->name);
402
403 vllist = afs_dns_query(cell, &expiry);
404 if (IS_ERR(vllist)) {
405 ret = PTR_ERR(vllist);
406
407 _debug("%s: fail %d", cell->name, ret);
408 if (ret == -ENOMEM)
409 goto out_wake;
410
411 vllist = afs_alloc_vlserver_list(0);
412 if (!vllist) {
413 if (ret >= 0)
414 ret = -ENOMEM;
415 goto out_wake;
416 }
417
418 switch (ret) {
419 case -ENODATA:
420 case -EDESTADDRREQ:
421 vllist->status = DNS_LOOKUP_GOT_NOT_FOUND;
422 break;
423 case -EAGAIN:
424 case -ECONNREFUSED:
425 vllist->status = DNS_LOOKUP_GOT_TEMP_FAILURE;
426 break;
427 default:
428 vllist->status = DNS_LOOKUP_GOT_LOCAL_FAILURE;
429 break;
430 }
431 }
432
433 _debug("%s: got list %d %d", cell->name, vllist->source, vllist->status);
434 cell->dns_status = vllist->status;
435
436 now = ktime_get_real_seconds();
437 if (min_ttl > max_ttl)
438 max_ttl = min_ttl;
439 if (expiry < now + min_ttl)
440 expiry = now + min_ttl;
441 else if (expiry > now + max_ttl)
442 expiry = now + max_ttl;
443
444 _debug("%s: status %d", cell->name, vllist->status);
445 if (vllist->source == DNS_RECORD_UNAVAILABLE) {
446 switch (vllist->status) {
447 case DNS_LOOKUP_GOT_NOT_FOUND:
448 /* The DNS said that the cell does not exist or there
449 * weren't any addresses to be had.
450 */
451 cell->dns_expiry = expiry;
452 break;
453
454 case DNS_LOOKUP_BAD:
455 case DNS_LOOKUP_GOT_LOCAL_FAILURE:
456 case DNS_LOOKUP_GOT_TEMP_FAILURE:
457 case DNS_LOOKUP_GOT_NS_FAILURE:
458 default:
459 cell->dns_expiry = now + 10;
460 break;
461 }
462 } else {
463 cell->dns_expiry = expiry;
464 }
465
466 /* Replace the VL server list if the new record has servers or the old
467 * record doesn't.
468 */
469 write_lock(&cell->vl_servers_lock);
470 p = rcu_dereference_protected(cell->vl_servers, true);
471 if (vllist->nr_servers > 0 || p->nr_servers == 0) {
472 rcu_assign_pointer(cell->vl_servers, vllist);
473 cell->dns_source = vllist->source;
474 old = p;
475 }
476 write_unlock(&cell->vl_servers_lock);
477 afs_put_vlserverlist(cell->net, old);
478
479 out_wake:
480 smp_store_release(&cell->dns_lookup_count,
481 cell->dns_lookup_count + 1); /* vs source/status */
482 wake_up_var(&cell->dns_lookup_count);
483 _leave(" = %d", ret);
484 return ret;
485 }
486
487 /*
488 * Destroy a cell record
489 */
490 static void afs_cell_destroy(struct rcu_head *rcu)
491 {
492 struct afs_cell *cell = container_of(rcu, struct afs_cell, rcu);
493 struct afs_net *net = cell->net;
494 int r;
495
496 _enter("%p{%s}", cell, cell->name);
497
498 r = refcount_read(&cell->ref);
499 ASSERTCMP(r, ==, 0);
500 trace_afs_cell(cell->debug_id, r, atomic_read(&cell->active), afs_cell_trace_free);
501
502 afs_put_vlserverlist(net, rcu_access_pointer(cell->vl_servers));
503 afs_unuse_cell(net, cell->alias_of, afs_cell_trace_unuse_alias);
504 key_put(cell->anonymous_key);
505 kfree(cell->name);
506 kfree(cell);
507
508 afs_dec_cells_outstanding(net);
509 _leave(" [destroyed]");
510 }
511
512 /*
513 * Queue the cell manager.
514 */
515 static void afs_queue_cell_manager(struct afs_net *net)
516 {
517 int outstanding = atomic_inc_return(&net->cells_outstanding);
518
519 _enter("%d", outstanding);
520
521 if (!queue_work(afs_wq, &net->cells_manager))
522 afs_dec_cells_outstanding(net);
523 }
524
525 /*
526 * Cell management timer. We have an increment on cells_outstanding that we
527 * need to pass along to the work item.
528 */
529 void afs_cells_timer(struct timer_list *timer)
530 {
531 struct afs_net *net = container_of(timer, struct afs_net, cells_timer);
532
533 _enter("");
534 if (!queue_work(afs_wq, &net->cells_manager))
535 afs_dec_cells_outstanding(net);
536 }
537
538 /*
539 * Get a reference on a cell record.
540 */
541 struct afs_cell *afs_get_cell(struct afs_cell *cell, enum afs_cell_trace reason)
542 {
543 int r;
544
545 __refcount_inc(&cell->ref, &r);
546 trace_afs_cell(cell->debug_id, r + 1, atomic_read(&cell->active), reason);
547 return cell;
548 }
549
550 /*
551 * Drop a reference on a cell record.
552 */
553 void afs_put_cell(struct afs_cell *cell, enum afs_cell_trace reason)
554 {
555 if (cell) {
556 unsigned int debug_id = cell->debug_id;
557 unsigned int a;
558 bool zero;
559 int r;
560
561 a = atomic_read(&cell->active);
562 zero = __refcount_dec_and_test(&cell->ref, &r);
563 trace_afs_cell(debug_id, r - 1, a, reason);
564 if (zero) {
565 a = atomic_read(&cell->active);
566 WARN(a != 0, "Cell active count %u > 0\n", a);
567 call_rcu(&cell->rcu, afs_cell_destroy);
568 }
569 }
570 }
571
572 /*
573 * Note a cell becoming more active.
574 */
575 struct afs_cell *afs_use_cell(struct afs_cell *cell, enum afs_cell_trace reason)
576 {
577 int r, a;
578
579 r = refcount_read(&cell->ref);
580 WARN_ON(r == 0);
581 a = atomic_inc_return(&cell->active);
582 trace_afs_cell(cell->debug_id, r, a, reason);
583 return cell;
584 }
585
586 /*
587 * Record a cell becoming less active. When the active counter reaches 1, it
588 * is scheduled for destruction, but may get reactivated.
589 */
590 void afs_unuse_cell(struct afs_net *net, struct afs_cell *cell, enum afs_cell_trace reason)
591 {
592 unsigned int debug_id;
593 time64_t now, expire_delay;
594 int r, a;
595
596 if (!cell)
597 return;
598
599 _enter("%s", cell->name);
600
601 now = ktime_get_real_seconds();
602 cell->last_inactive = now;
603 expire_delay = 0;
604 if (cell->vl_servers->nr_servers)
605 expire_delay = afs_cell_gc_delay;
606
607 debug_id = cell->debug_id;
608 r = refcount_read(&cell->ref);
609 a = atomic_dec_return(&cell->active);
610 trace_afs_cell(debug_id, r, a, reason);
611 WARN_ON(a == 0);
612 if (a == 1)
613 /* 'cell' may now be garbage collected. */
614 afs_set_cell_timer(net, expire_delay);
615 }
616
617 /*
618 * Note that a cell has been seen.
619 */
620 void afs_see_cell(struct afs_cell *cell, enum afs_cell_trace reason)
621 {
622 int r, a;
623
624 r = refcount_read(&cell->ref);
625 a = atomic_read(&cell->active);
626 trace_afs_cell(cell->debug_id, r, a, reason);
627 }
628
629 /*
630 * Queue a cell for management, giving the workqueue a ref to hold.
631 */
632 void afs_queue_cell(struct afs_cell *cell, enum afs_cell_trace reason)
633 {
634 afs_get_cell(cell, reason);
635 if (!queue_work(afs_wq, &cell->manager))
636 afs_put_cell(cell, afs_cell_trace_put_queue_fail);
637 }
638
639 /*
640 * Allocate a key to use as a placeholder for anonymous user security.
641 */
642 static int afs_alloc_anon_key(struct afs_cell *cell)
643 {
644 struct key *key;
645 char keyname[4 + AFS_MAXCELLNAME + 1], *cp, *dp;
646
647 /* Create a key to represent an anonymous user. */
648 memcpy(keyname, "afs@", 4);
649 dp = keyname + 4;
650 cp = cell->name;
651 do {
652 *dp++ = tolower(*cp);
653 } while (*cp++);
654
655 key = rxrpc_get_null_key(keyname);
656 if (IS_ERR(key))
657 return PTR_ERR(key);
658
659 cell->anonymous_key = key;
660
661 _debug("anon key %p{%x}",
662 cell->anonymous_key, key_serial(cell->anonymous_key));
663 return 0;
664 }
665
666 /*
667 * Activate a cell.
668 */
669 static int afs_activate_cell(struct afs_net *net, struct afs_cell *cell)
670 {
671 struct hlist_node **p;
672 struct afs_cell *pcell;
673 int ret;
674
675 if (!cell->anonymous_key) {
676 ret = afs_alloc_anon_key(cell);
677 if (ret < 0)
678 return ret;
679 }
680
681 ret = afs_proc_cell_setup(cell);
682 if (ret < 0)
683 return ret;
684
685 mutex_lock(&net->proc_cells_lock);
686 for (p = &net->proc_cells.first; *p; p = &(*p)->next) {
687 pcell = hlist_entry(*p, struct afs_cell, proc_link);
688 if (strcmp(cell->name, pcell->name) < 0)
689 break;
690 }
691
692 cell->proc_link.pprev = p;
693 cell->proc_link.next = *p;
694 rcu_assign_pointer(*p, &cell->proc_link.next);
695 if (cell->proc_link.next)
696 cell->proc_link.next->pprev = &cell->proc_link.next;
697
698 afs_dynroot_mkdir(net, cell);
699 mutex_unlock(&net->proc_cells_lock);
700 return 0;
701 }
702
703 /*
704 * Deactivate a cell.
705 */
706 static void afs_deactivate_cell(struct afs_net *net, struct afs_cell *cell)
707 {
708 _enter("%s", cell->name);
709
710 afs_proc_cell_remove(cell);
711
712 mutex_lock(&net->proc_cells_lock);
713 hlist_del_rcu(&cell->proc_link);
714 afs_dynroot_rmdir(net, cell);
715 mutex_unlock(&net->proc_cells_lock);
716
717 _leave("");
718 }
719
720 /*
721 * Manage a cell record, initialising and destroying it, maintaining its DNS
722 * records.
723 */
724 static void afs_manage_cell(struct afs_cell *cell)
725 {
726 struct afs_net *net = cell->net;
727 int ret, active;
728
729 _enter("%s", cell->name);
730
731 again:
732 _debug("state %u", cell->state);
733 switch (cell->state) {
734 case AFS_CELL_INACTIVE:
735 case AFS_CELL_FAILED:
736 down_write(&net->cells_lock);
737 active = 1;
738 if (atomic_try_cmpxchg_relaxed(&cell->active, &active, 0)) {
739 rb_erase(&cell->net_node, &net->cells);
740 trace_afs_cell(cell->debug_id, refcount_read(&cell->ref), 0,
741 afs_cell_trace_unuse_delete);
742 smp_store_release(&cell->state, AFS_CELL_REMOVED);
743 }
744 up_write(&net->cells_lock);
745 if (cell->state == AFS_CELL_REMOVED) {
746 wake_up_var(&cell->state);
747 goto final_destruction;
748 }
749 if (cell->state == AFS_CELL_FAILED)
750 goto done;
751 smp_store_release(&cell->state, AFS_CELL_UNSET);
752 wake_up_var(&cell->state);
753 goto again;
754
755 case AFS_CELL_UNSET:
756 smp_store_release(&cell->state, AFS_CELL_ACTIVATING);
757 wake_up_var(&cell->state);
758 goto again;
759
760 case AFS_CELL_ACTIVATING:
761 ret = afs_activate_cell(net, cell);
762 if (ret < 0)
763 goto activation_failed;
764
765 smp_store_release(&cell->state, AFS_CELL_ACTIVE);
766 wake_up_var(&cell->state);
767 goto again;
768
769 case AFS_CELL_ACTIVE:
770 if (atomic_read(&cell->active) > 1) {
771 if (test_and_clear_bit(AFS_CELL_FL_DO_LOOKUP, &cell->flags)) {
772 ret = afs_update_cell(cell);
773 if (ret < 0)
774 cell->error = ret;
775 }
776 goto done;
777 }
778 smp_store_release(&cell->state, AFS_CELL_DEACTIVATING);
779 wake_up_var(&cell->state);
780 goto again;
781
782 case AFS_CELL_DEACTIVATING:
783 if (atomic_read(&cell->active) > 1)
784 goto reverse_deactivation;
785 afs_deactivate_cell(net, cell);
786 smp_store_release(&cell->state, AFS_CELL_INACTIVE);
787 wake_up_var(&cell->state);
788 goto again;
789
790 case AFS_CELL_REMOVED:
791 goto done;
792
793 default:
794 break;
795 }
796 _debug("bad state %u", cell->state);
797 BUG(); /* Unhandled state */
798
799 activation_failed:
800 cell->error = ret;
801 afs_deactivate_cell(net, cell);
802
803 smp_store_release(&cell->state, AFS_CELL_FAILED); /* vs error */
804 wake_up_var(&cell->state);
805 goto again;
806
807 reverse_deactivation:
808 smp_store_release(&cell->state, AFS_CELL_ACTIVE);
809 wake_up_var(&cell->state);
810 _leave(" [deact->act]");
811 return;
812
813 done:
814 _leave(" [done %u]", cell->state);
815 return;
816
817 final_destruction:
818 /* The root volume is pinning the cell */
819 afs_put_volume(cell->root_volume, afs_volume_trace_put_cell_root);
820 cell->root_volume = NULL;
821 afs_put_cell(cell, afs_cell_trace_put_destroy);
822 }
823
824 static void afs_manage_cell_work(struct work_struct *work)
825 {
826 struct afs_cell *cell = container_of(work, struct afs_cell, manager);
827
828 afs_manage_cell(cell);
829 afs_put_cell(cell, afs_cell_trace_put_queue_work);
830 }
831
832 /*
833 * Manage the records of cells known to a network namespace. This includes
834 * updating the DNS records and garbage collecting unused cells that were
835 * automatically added.
836 *
837 * Note that constructed cell records may only be removed from net->cells by
838 * this work item, so it is safe for this work item to stash a cursor pointing
839 * into the tree and then return to caller (provided it skips cells that are
840 * still under construction).
841 *
842 * Note also that we were given an increment on net->cells_outstanding by
843 * whoever queued us that we need to deal with before returning.
844 */
845 void afs_manage_cells(struct work_struct *work)
846 {
847 struct afs_net *net = container_of(work, struct afs_net, cells_manager);
848 struct rb_node *cursor;
849 time64_t now = ktime_get_real_seconds(), next_manage = TIME64_MAX;
850 bool purging = !net->live;
851
852 _enter("");
853
854 /* Trawl the cell database looking for cells that have expired from
855 * lack of use and cells whose DNS results have expired and dispatch
856 * their managers.
857 */
858 down_read(&net->cells_lock);
859
860 for (cursor = rb_first(&net->cells); cursor; cursor = rb_next(cursor)) {
861 struct afs_cell *cell =
862 rb_entry(cursor, struct afs_cell, net_node);
863 unsigned active;
864 bool sched_cell = false;
865
866 active = atomic_read(&cell->active);
867 trace_afs_cell(cell->debug_id, refcount_read(&cell->ref),
868 active, afs_cell_trace_manage);
869
870 ASSERTCMP(active, >=, 1);
871
872 if (purging) {
873 if (test_and_clear_bit(AFS_CELL_FL_NO_GC, &cell->flags)) {
874 active = atomic_dec_return(&cell->active);
875 trace_afs_cell(cell->debug_id, refcount_read(&cell->ref),
876 active, afs_cell_trace_unuse_pin);
877 }
878 }
879
880 if (active == 1) {
881 struct afs_vlserver_list *vllist;
882 time64_t expire_at = cell->last_inactive;
883
884 read_lock(&cell->vl_servers_lock);
885 vllist = rcu_dereference_protected(
886 cell->vl_servers,
887 lockdep_is_held(&cell->vl_servers_lock));
888 if (vllist->nr_servers > 0)
889 expire_at += afs_cell_gc_delay;
890 read_unlock(&cell->vl_servers_lock);
891 if (purging || expire_at <= now)
892 sched_cell = true;
893 else if (expire_at < next_manage)
894 next_manage = expire_at;
895 }
896
897 if (!purging) {
898 if (test_bit(AFS_CELL_FL_DO_LOOKUP, &cell->flags))
899 sched_cell = true;
900 }
901
902 if (sched_cell)
903 afs_queue_cell(cell, afs_cell_trace_get_queue_manage);
904 }
905
906 up_read(&net->cells_lock);
907
908 /* Update the timer on the way out. We have to pass an increment on
909 * cells_outstanding in the namespace that we are in to the timer or
910 * the work scheduler.
911 */
912 if (!purging && next_manage < TIME64_MAX) {
913 now = ktime_get_real_seconds();
914
915 if (next_manage - now <= 0) {
916 if (queue_work(afs_wq, &net->cells_manager))
917 atomic_inc(&net->cells_outstanding);
918 } else {
919 afs_set_cell_timer(net, next_manage - now);
920 }
921 }
922
923 afs_dec_cells_outstanding(net);
924 _leave(" [%d]", atomic_read(&net->cells_outstanding));
925 }
926
927 /*
928 * Purge in-memory cell database.
929 */
930 void afs_cell_purge(struct afs_net *net)
931 {
932 struct afs_cell *ws;
933
934 _enter("");
935
936 down_write(&net->cells_lock);
937 ws = net->ws_cell;
938 net->ws_cell = NULL;
939 up_write(&net->cells_lock);
940 afs_unuse_cell(net, ws, afs_cell_trace_unuse_ws);
941
942 _debug("del timer");
943 if (del_timer_sync(&net->cells_timer))
944 atomic_dec(&net->cells_outstanding);
945
946 _debug("kick mgr");
947 afs_queue_cell_manager(net);
948
949 _debug("wait");
950 wait_var_event(&net->cells_outstanding,
951 !atomic_read(&net->cells_outstanding));
952 _leave("");
953 }
954
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