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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * linux/fs/lockd/svclock.c
4 *
5 * Handling of server-side locks, mostly of the blocked variety.
6 * This is the ugliest part of lockd because we tread on very thin ice.
7 * GRANT and CANCEL calls may get stuck, meet in mid-flight, etc.
8 * IMNSHO introducing the grant callback into the NLM protocol was one
9 * of the worst ideas Sun ever had. Except maybe for the idea of doing
10 * NFS file locking at all.
11 *
12 * I'm trying hard to avoid race conditions by protecting most accesses
13 * to a file's list of blocked locks through a semaphore. The global
14 * list of blocked locks is not protected in this fashion however.
15 * Therefore, some functions (such as the RPC callback for the async grant
16 * call) move blocked locks towards the head of the list *while some other
17 * process might be traversing it*. This should not be a problem in
18 * practice, because this will only cause functions traversing the list
19 * to visit some blocks twice.
20 *
21 * Copyright (C) 1996, Olaf Kirch <okir@monad.swb.de>
22 */
23
24#include <linux/types.h>
25#include <linux/slab.h>
26#include <linux/errno.h>
27#include <linux/kernel.h>
28#include <linux/sched.h>
29#include <linux/sunrpc/clnt.h>
30#include <linux/sunrpc/svc_xprt.h>
31#include <linux/lockd/nlm.h>
32#include <linux/lockd/lockd.h>
33#include <linux/kthread.h>
34
35#define NLMDBG_FACILITY NLMDBG_SVCLOCK
36
37#ifdef CONFIG_LOCKD_V4
38#define nlm_deadlock nlm4_deadlock
39#else
40#define nlm_deadlock nlm_lck_denied
41#endif
42
43static void nlmsvc_release_block(struct nlm_block *block);
44static void nlmsvc_insert_block(struct nlm_block *block, unsigned long);
45static void nlmsvc_remove_block(struct nlm_block *block);
46
47static int nlmsvc_setgrantargs(struct nlm_rqst *call, struct nlm_lock *lock);
48static void nlmsvc_freegrantargs(struct nlm_rqst *call);
49static const struct rpc_call_ops nlmsvc_grant_ops;
50
51/*
52 * The list of blocked locks to retry
53 */
54static LIST_HEAD(nlm_blocked);
55static DEFINE_SPINLOCK(nlm_blocked_lock);
56
57#if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
58static const char *nlmdbg_cookie2a(const struct nlm_cookie *cookie)
59{
60 /*
61 * We can get away with a static buffer because this is only called
62 * from lockd, which is single-threaded.
63 */
64 static char buf[2*NLM_MAXCOOKIELEN+1];
65 unsigned int i, len = sizeof(buf);
66 char *p = buf;
67
68 len--; /* allow for trailing \0 */
69 if (len < 3)
70 return "???";
71 for (i = 0 ; i < cookie->len ; i++) {
72 if (len < 2) {
73 strcpy(p-3, "...");
74 break;
75 }
76 sprintf(p, "%02x", cookie->data[i]);
77 p += 2;
78 len -= 2;
79 }
80 *p = '\0';
81
82 return buf;
83}
84#endif
85
86/*
87 * Insert a blocked lock into the global list
88 */
89static void
90nlmsvc_insert_block_locked(struct nlm_block *block, unsigned long when)
91{
92 struct nlm_block *b;
93 struct list_head *pos;
94
95 dprintk("lockd: nlmsvc_insert_block(%p, %ld)\n", block, when);
96 if (list_empty(&block->b_list)) {
97 kref_get(&block->b_count);
98 } else {
99 list_del_init(&block->b_list);
100 }
101
102 pos = &nlm_blocked;
103 if (when != NLM_NEVER) {
104 if ((when += jiffies) == NLM_NEVER)
105 when ++;
106 list_for_each(pos, &nlm_blocked) {
107 b = list_entry(pos, struct nlm_block, b_list);
108 if (time_after(b->b_when,when) || b->b_when == NLM_NEVER)
109 break;
110 }
111 /* On normal exit from the loop, pos == &nlm_blocked,
112 * so we will be adding to the end of the list - good
113 */
114 }
115
116 list_add_tail(&block->b_list, pos);
117 block->b_when = when;
118}
119
120static void nlmsvc_insert_block(struct nlm_block *block, unsigned long when)
121{
122 spin_lock(&nlm_blocked_lock);
123 nlmsvc_insert_block_locked(block, when);
124 spin_unlock(&nlm_blocked_lock);
125}
126
127/*
128 * Remove a block from the global list
129 */
130static inline void
131nlmsvc_remove_block(struct nlm_block *block)
132{
133 if (!list_empty(&block->b_list)) {
134 spin_lock(&nlm_blocked_lock);
135 list_del_init(&block->b_list);
136 spin_unlock(&nlm_blocked_lock);
137 nlmsvc_release_block(block);
138 }
139}
140
141/*
142 * Find a block for a given lock
143 */
144static struct nlm_block *
145nlmsvc_lookup_block(struct nlm_file *file, struct nlm_lock *lock)
146{
147 struct nlm_block *block;
148 struct file_lock *fl;
149
150 dprintk("lockd: nlmsvc_lookup_block f=%p pd=%d %Ld-%Ld ty=%d\n",
151 file, lock->fl.fl_pid,
152 (long long)lock->fl.fl_start,
153 (long long)lock->fl.fl_end, lock->fl.fl_type);
154 list_for_each_entry(block, &nlm_blocked, b_list) {
155 fl = &block->b_call->a_args.lock.fl;
156 dprintk("lockd: check f=%p pd=%d %Ld-%Ld ty=%d cookie=%s\n",
157 block->b_file, fl->fl_pid,
158 (long long)fl->fl_start,
159 (long long)fl->fl_end, fl->fl_type,
160 nlmdbg_cookie2a(&block->b_call->a_args.cookie));
161 if (block->b_file == file && nlm_compare_locks(fl, &lock->fl)) {
162 kref_get(&block->b_count);
163 return block;
164 }
165 }
166
167 return NULL;
168}
169
170static inline int nlm_cookie_match(struct nlm_cookie *a, struct nlm_cookie *b)
171{
172 if (a->len != b->len)
173 return 0;
174 if (memcmp(a->data, b->data, a->len))
175 return 0;
176 return 1;
177}
178
179/*
180 * Find a block with a given NLM cookie.
181 */
182static inline struct nlm_block *
183nlmsvc_find_block(struct nlm_cookie *cookie)
184{
185 struct nlm_block *block;
186
187 list_for_each_entry(block, &nlm_blocked, b_list) {
188 if (nlm_cookie_match(&block->b_call->a_args.cookie,cookie))
189 goto found;
190 }
191
192 return NULL;
193
194found:
195 dprintk("nlmsvc_find_block(%s): block=%p\n", nlmdbg_cookie2a(cookie), block);
196 kref_get(&block->b_count);
197 return block;
198}
199
200/*
201 * Create a block and initialize it.
202 *
203 * Note: we explicitly set the cookie of the grant reply to that of
204 * the blocked lock request. The spec explicitly mentions that the client
205 * should _not_ rely on the callback containing the same cookie as the
206 * request, but (as I found out later) that's because some implementations
207 * do just this. Never mind the standards comittees, they support our
208 * logging industries.
209 *
210 * 10 years later: I hope we can safely ignore these old and broken
211 * clients by now. Let's fix this so we can uniquely identify an incoming
212 * GRANTED_RES message by cookie, without having to rely on the client's IP
213 * address. --okir
214 */
215static struct nlm_block *
216nlmsvc_create_block(struct svc_rqst *rqstp, struct nlm_host *host,
217 struct nlm_file *file, struct nlm_lock *lock,
218 struct nlm_cookie *cookie)
219{
220 struct nlm_block *block;
221 struct nlm_rqst *call = NULL;
222
223 call = nlm_alloc_call(host);
224 if (call == NULL)
225 return NULL;
226
227 /* Allocate memory for block, and initialize arguments */
228 block = kzalloc(sizeof(*block), GFP_KERNEL);
229 if (block == NULL)
230 goto failed;
231 kref_init(&block->b_count);
232 INIT_LIST_HEAD(&block->b_list);
233 INIT_LIST_HEAD(&block->b_flist);
234
235 if (!nlmsvc_setgrantargs(call, lock))
236 goto failed_free;
237
238 /* Set notifier function for VFS, and init args */
239 call->a_args.lock.fl.fl_flags |= FL_SLEEP;
240 call->a_args.lock.fl.fl_lmops = &nlmsvc_lock_operations;
241 nlmclnt_next_cookie(&call->a_args.cookie);
242
243 dprintk("lockd: created block %p...\n", block);
244
245 /* Create and initialize the block */
246 block->b_daemon = rqstp->rq_server;
247 block->b_host = host;
248 block->b_file = file;
249 file->f_count++;
250
251 /* Add to file's list of blocks */
252 list_add(&block->b_flist, &file->f_blocks);
253
254 /* Set up RPC arguments for callback */
255 block->b_call = call;
256 call->a_flags = RPC_TASK_ASYNC;
257 call->a_block = block;
258
259 return block;
260
261failed_free:
262 kfree(block);
263failed:
264 nlmsvc_release_call(call);
265 return NULL;
266}
267
268/*
269 * Delete a block.
270 * It is the caller's responsibility to check whether the file
271 * can be closed hereafter.
272 */
273static int nlmsvc_unlink_block(struct nlm_block *block)
274{
275 int status;
276 dprintk("lockd: unlinking block %p...\n", block);
277
278 /* Remove block from list */
279 status = locks_delete_block(&block->b_call->a_args.lock.fl);
280 nlmsvc_remove_block(block);
281 return status;
282}
283
284static void nlmsvc_free_block(struct kref *kref)
285{
286 struct nlm_block *block = container_of(kref, struct nlm_block, b_count);
287 struct nlm_file *file = block->b_file;
288
289 dprintk("lockd: freeing block %p...\n", block);
290
291 /* Remove block from file's list of blocks */
292 list_del_init(&block->b_flist);
293 mutex_unlock(&file->f_mutex);
294
295 nlmsvc_freegrantargs(block->b_call);
296 nlmsvc_release_call(block->b_call);
297 nlm_release_file(block->b_file);
298 kfree(block);
299}
300
301static void nlmsvc_release_block(struct nlm_block *block)
302{
303 if (block != NULL)
304 kref_put_mutex(&block->b_count, nlmsvc_free_block, &block->b_file->f_mutex);
305}
306
307/*
308 * Loop over all blocks and delete blocks held by
309 * a matching host.
310 */
311void nlmsvc_traverse_blocks(struct nlm_host *host,
312 struct nlm_file *file,
313 nlm_host_match_fn_t match)
314{
315 struct nlm_block *block, *next;
316
317restart:
318 mutex_lock(&file->f_mutex);
319 list_for_each_entry_safe(block, next, &file->f_blocks, b_flist) {
320 if (!match(block->b_host, host))
321 continue;
322 /* Do not destroy blocks that are not on
323 * the global retry list - why? */
324 if (list_empty(&block->b_list))
325 continue;
326 kref_get(&block->b_count);
327 mutex_unlock(&file->f_mutex);
328 nlmsvc_unlink_block(block);
329 nlmsvc_release_block(block);
330 goto restart;
331 }
332 mutex_unlock(&file->f_mutex);
333}
334
335static struct nlm_lockowner *
336nlmsvc_get_lockowner(struct nlm_lockowner *lockowner)
337{
338 refcount_inc(&lockowner->count);
339 return lockowner;
340}
341
342static void nlmsvc_put_lockowner(struct nlm_lockowner *lockowner)
343{
344 if (!refcount_dec_and_lock(&lockowner->count, &lockowner->host->h_lock))
345 return;
346 list_del(&lockowner->list);
347 spin_unlock(&lockowner->host->h_lock);
348 nlmsvc_release_host(lockowner->host);
349 kfree(lockowner);
350}
351
352static struct nlm_lockowner *__nlmsvc_find_lockowner(struct nlm_host *host, pid_t pid)
353{
354 struct nlm_lockowner *lockowner;
355 list_for_each_entry(lockowner, &host->h_lockowners, list) {
356 if (lockowner->pid != pid)
357 continue;
358 return nlmsvc_get_lockowner(lockowner);
359 }
360 return NULL;
361}
362
363static struct nlm_lockowner *nlmsvc_find_lockowner(struct nlm_host *host, pid_t pid)
364{
365 struct nlm_lockowner *res, *new = NULL;
366
367 spin_lock(&host->h_lock);
368 res = __nlmsvc_find_lockowner(host, pid);
369
370 if (res == NULL) {
371 spin_unlock(&host->h_lock);
372 new = kmalloc(sizeof(*res), GFP_KERNEL);
373 spin_lock(&host->h_lock);
374 res = __nlmsvc_find_lockowner(host, pid);
375 if (res == NULL && new != NULL) {
376 res = new;
377 /* fs/locks.c will manage the refcount through lock_ops */
378 refcount_set(&new->count, 1);
379 new->pid = pid;
380 new->host = nlm_get_host(host);
381 list_add(&new->list, &host->h_lockowners);
382 new = NULL;
383 }
384 }
385
386 spin_unlock(&host->h_lock);
387 kfree(new);
388 return res;
389}
390
391void
392nlmsvc_release_lockowner(struct nlm_lock *lock)
393{
394 if (lock->fl.fl_owner)
395 nlmsvc_put_lockowner(lock->fl.fl_owner);
396}
397
398void nlmsvc_locks_init_private(struct file_lock *fl, struct nlm_host *host,
399 pid_t pid)
400{
401 fl->fl_owner = nlmsvc_find_lockowner(host, pid);
402}
403
404/*
405 * Initialize arguments for GRANTED call. The nlm_rqst structure
406 * has been cleared already.
407 */
408static int nlmsvc_setgrantargs(struct nlm_rqst *call, struct nlm_lock *lock)
409{
410 locks_copy_lock(&call->a_args.lock.fl, &lock->fl);
411 memcpy(&call->a_args.lock.fh, &lock->fh, sizeof(call->a_args.lock.fh));
412 call->a_args.lock.caller = utsname()->nodename;
413 call->a_args.lock.oh.len = lock->oh.len;
414
415 /* set default data area */
416 call->a_args.lock.oh.data = call->a_owner;
417 call->a_args.lock.svid = ((struct nlm_lockowner *)lock->fl.fl_owner)->pid;
418
419 if (lock->oh.len > NLMCLNT_OHSIZE) {
420 void *data = kmalloc(lock->oh.len, GFP_KERNEL);
421 if (!data)
422 return 0;
423 call->a_args.lock.oh.data = (u8 *) data;
424 }
425
426 memcpy(call->a_args.lock.oh.data, lock->oh.data, lock->oh.len);
427 return 1;
428}
429
430static void nlmsvc_freegrantargs(struct nlm_rqst *call)
431{
432 if (call->a_args.lock.oh.data != call->a_owner)
433 kfree(call->a_args.lock.oh.data);
434
435 locks_release_private(&call->a_args.lock.fl);
436}
437
438/*
439 * Deferred lock request handling for non-blocking lock
440 */
441static __be32
442nlmsvc_defer_lock_rqst(struct svc_rqst *rqstp, struct nlm_block *block)
443{
444 __be32 status = nlm_lck_denied_nolocks;
445
446 block->b_flags |= B_QUEUED;
447
448 nlmsvc_insert_block(block, NLM_TIMEOUT);
449
450 block->b_cache_req = &rqstp->rq_chandle;
451 if (rqstp->rq_chandle.defer) {
452 block->b_deferred_req =
453 rqstp->rq_chandle.defer(block->b_cache_req);
454 if (block->b_deferred_req != NULL)
455 status = nlm_drop_reply;
456 }
457 dprintk("lockd: nlmsvc_defer_lock_rqst block %p flags %d status %d\n",
458 block, block->b_flags, ntohl(status));
459
460 return status;
461}
462
463/*
464 * Attempt to establish a lock, and if it can't be granted, block it
465 * if required.
466 */
467__be32
468nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file,
469 struct nlm_host *host, struct nlm_lock *lock, int wait,
470 struct nlm_cookie *cookie, int reclaim)
471{
472 struct nlm_block *block = NULL;
473 int error;
474 __be32 ret;
475
476 dprintk("lockd: nlmsvc_lock(%s/%ld, ty=%d, pi=%d, %Ld-%Ld, bl=%d)\n",
477 locks_inode(file->f_file)->i_sb->s_id,
478 locks_inode(file->f_file)->i_ino,
479 lock->fl.fl_type, lock->fl.fl_pid,
480 (long long)lock->fl.fl_start,
481 (long long)lock->fl.fl_end,
482 wait);
483
484 /* Lock file against concurrent access */
485 mutex_lock(&file->f_mutex);
486 /* Get existing block (in case client is busy-waiting)
487 * or create new block
488 */
489 block = nlmsvc_lookup_block(file, lock);
490 if (block == NULL) {
491 block = nlmsvc_create_block(rqstp, host, file, lock, cookie);
492 ret = nlm_lck_denied_nolocks;
493 if (block == NULL)
494 goto out;
495 lock = &block->b_call->a_args.lock;
496 } else
497 lock->fl.fl_flags &= ~FL_SLEEP;
498
499 if (block->b_flags & B_QUEUED) {
500 dprintk("lockd: nlmsvc_lock deferred block %p flags %d\n",
501 block, block->b_flags);
502 if (block->b_granted) {
503 nlmsvc_unlink_block(block);
504 ret = nlm_granted;
505 goto out;
506 }
507 if (block->b_flags & B_TIMED_OUT) {
508 nlmsvc_unlink_block(block);
509 ret = nlm_lck_denied;
510 goto out;
511 }
512 ret = nlm_drop_reply;
513 goto out;
514 }
515
516 if (locks_in_grace(SVC_NET(rqstp)) && !reclaim) {
517 ret = nlm_lck_denied_grace_period;
518 goto out;
519 }
520 if (reclaim && !locks_in_grace(SVC_NET(rqstp))) {
521 ret = nlm_lck_denied_grace_period;
522 goto out;
523 }
524
525 if (!wait)
526 lock->fl.fl_flags &= ~FL_SLEEP;
527 error = vfs_lock_file(file->f_file, F_SETLK, &lock->fl, NULL);
528 lock->fl.fl_flags &= ~FL_SLEEP;
529
530 dprintk("lockd: vfs_lock_file returned %d\n", error);
531 switch (error) {
532 case 0:
533 ret = nlm_granted;
534 goto out;
535 case -EAGAIN:
536 /*
537 * If this is a blocking request for an
538 * already pending lock request then we need
539 * to put it back on lockd's block list
540 */
541 if (wait)
542 break;
543 ret = nlm_lck_denied;
544 goto out;
545 case FILE_LOCK_DEFERRED:
546 if (wait)
547 break;
548 /* Filesystem lock operation is in progress
549 Add it to the queue waiting for callback */
550 ret = nlmsvc_defer_lock_rqst(rqstp, block);
551 goto out;
552 case -EDEADLK:
553 ret = nlm_deadlock;
554 goto out;
555 default: /* includes ENOLCK */
556 ret = nlm_lck_denied_nolocks;
557 goto out;
558 }
559
560 ret = nlm_lck_blocked;
561
562 /* Append to list of blocked */
563 nlmsvc_insert_block(block, NLM_NEVER);
564out:
565 mutex_unlock(&file->f_mutex);
566 nlmsvc_release_block(block);
567 dprintk("lockd: nlmsvc_lock returned %u\n", ret);
568 return ret;
569}
570
571/*
572 * Test for presence of a conflicting lock.
573 */
574__be32
575nlmsvc_testlock(struct svc_rqst *rqstp, struct nlm_file *file,
576 struct nlm_host *host, struct nlm_lock *lock,
577 struct nlm_lock *conflock, struct nlm_cookie *cookie)
578{
579 int error;
580 __be32 ret;
581 struct nlm_lockowner *test_owner;
582
583 dprintk("lockd: nlmsvc_testlock(%s/%ld, ty=%d, %Ld-%Ld)\n",
584 locks_inode(file->f_file)->i_sb->s_id,
585 locks_inode(file->f_file)->i_ino,
586 lock->fl.fl_type,
587 (long long)lock->fl.fl_start,
588 (long long)lock->fl.fl_end);
589
590 if (locks_in_grace(SVC_NET(rqstp))) {
591 ret = nlm_lck_denied_grace_period;
592 goto out;
593 }
594
595 /* If there's a conflicting lock, remember to clean up the test lock */
596 test_owner = (struct nlm_lockowner *)lock->fl.fl_owner;
597
598 error = vfs_test_lock(file->f_file, &lock->fl);
599 if (error) {
600 /* We can't currently deal with deferred test requests */
601 if (error == FILE_LOCK_DEFERRED)
602 WARN_ON_ONCE(1);
603
604 ret = nlm_lck_denied_nolocks;
605 goto out;
606 }
607
608 if (lock->fl.fl_type == F_UNLCK) {
609 ret = nlm_granted;
610 goto out;
611 }
612
613 dprintk("lockd: conflicting lock(ty=%d, %Ld-%Ld)\n",
614 lock->fl.fl_type, (long long)lock->fl.fl_start,
615 (long long)lock->fl.fl_end);
616 conflock->caller = "somehost"; /* FIXME */
617 conflock->len = strlen(conflock->caller);
618 conflock->oh.len = 0; /* don't return OH info */
619 conflock->svid = lock->fl.fl_pid;
620 conflock->fl.fl_type = lock->fl.fl_type;
621 conflock->fl.fl_start = lock->fl.fl_start;
622 conflock->fl.fl_end = lock->fl.fl_end;
623 locks_release_private(&lock->fl);
624
625 /* Clean up the test lock */
626 lock->fl.fl_owner = NULL;
627 nlmsvc_put_lockowner(test_owner);
628
629 ret = nlm_lck_denied;
630out:
631 return ret;
632}
633
634/*
635 * Remove a lock.
636 * This implies a CANCEL call: We send a GRANT_MSG, the client replies
637 * with a GRANT_RES call which gets lost, and calls UNLOCK immediately
638 * afterwards. In this case the block will still be there, and hence
639 * must be removed.
640 */
641__be32
642nlmsvc_unlock(struct net *net, struct nlm_file *file, struct nlm_lock *lock)
643{
644 int error;
645
646 dprintk("lockd: nlmsvc_unlock(%s/%ld, pi=%d, %Ld-%Ld)\n",
647 locks_inode(file->f_file)->i_sb->s_id,
648 locks_inode(file->f_file)->i_ino,
649 lock->fl.fl_pid,
650 (long long)lock->fl.fl_start,
651 (long long)lock->fl.fl_end);
652
653 /* First, cancel any lock that might be there */
654 nlmsvc_cancel_blocked(net, file, lock);
655
656 lock->fl.fl_type = F_UNLCK;
657 error = vfs_lock_file(file->f_file, F_SETLK, &lock->fl, NULL);
658
659 return (error < 0)? nlm_lck_denied_nolocks : nlm_granted;
660}
661
662/*
663 * Cancel a previously blocked request.
664 *
665 * A cancel request always overrides any grant that may currently
666 * be in progress.
667 * The calling procedure must check whether the file can be closed.
668 */
669__be32
670nlmsvc_cancel_blocked(struct net *net, struct nlm_file *file, struct nlm_lock *lock)
671{
672 struct nlm_block *block;
673 int status = 0;
674
675 dprintk("lockd: nlmsvc_cancel(%s/%ld, pi=%d, %Ld-%Ld)\n",
676 locks_inode(file->f_file)->i_sb->s_id,
677 locks_inode(file->f_file)->i_ino,
678 lock->fl.fl_pid,
679 (long long)lock->fl.fl_start,
680 (long long)lock->fl.fl_end);
681
682 if (locks_in_grace(net))
683 return nlm_lck_denied_grace_period;
684
685 mutex_lock(&file->f_mutex);
686 block = nlmsvc_lookup_block(file, lock);
687 mutex_unlock(&file->f_mutex);
688 if (block != NULL) {
689 vfs_cancel_lock(block->b_file->f_file,
690 &block->b_call->a_args.lock.fl);
691 status = nlmsvc_unlink_block(block);
692 nlmsvc_release_block(block);
693 }
694 return status ? nlm_lck_denied : nlm_granted;
695}
696
697/*
698 * This is a callback from the filesystem for VFS file lock requests.
699 * It will be used if lm_grant is defined and the filesystem can not
700 * respond to the request immediately.
701 * For SETLK or SETLKW request it will get the local posix lock.
702 * In all cases it will move the block to the head of nlm_blocked q where
703 * nlmsvc_retry_blocked() can send back a reply for SETLKW or revisit the
704 * deferred rpc for GETLK and SETLK.
705 */
706static void
707nlmsvc_update_deferred_block(struct nlm_block *block, int result)
708{
709 block->b_flags |= B_GOT_CALLBACK;
710 if (result == 0)
711 block->b_granted = 1;
712 else
713 block->b_flags |= B_TIMED_OUT;
714}
715
716static int nlmsvc_grant_deferred(struct file_lock *fl, int result)
717{
718 struct nlm_block *block;
719 int rc = -ENOENT;
720
721 spin_lock(&nlm_blocked_lock);
722 list_for_each_entry(block, &nlm_blocked, b_list) {
723 if (nlm_compare_locks(&block->b_call->a_args.lock.fl, fl)) {
724 dprintk("lockd: nlmsvc_notify_blocked block %p flags %d\n",
725 block, block->b_flags);
726 if (block->b_flags & B_QUEUED) {
727 if (block->b_flags & B_TIMED_OUT) {
728 rc = -ENOLCK;
729 break;
730 }
731 nlmsvc_update_deferred_block(block, result);
732 } else if (result == 0)
733 block->b_granted = 1;
734
735 nlmsvc_insert_block_locked(block, 0);
736 svc_wake_up(block->b_daemon);
737 rc = 0;
738 break;
739 }
740 }
741 spin_unlock(&nlm_blocked_lock);
742 if (rc == -ENOENT)
743 printk(KERN_WARNING "lockd: grant for unknown block\n");
744 return rc;
745}
746
747/*
748 * Unblock a blocked lock request. This is a callback invoked from the
749 * VFS layer when a lock on which we blocked is removed.
750 *
751 * This function doesn't grant the blocked lock instantly, but rather moves
752 * the block to the head of nlm_blocked where it can be picked up by lockd.
753 */
754static void
755nlmsvc_notify_blocked(struct file_lock *fl)
756{
757 struct nlm_block *block;
758
759 dprintk("lockd: VFS unblock notification for block %p\n", fl);
760 spin_lock(&nlm_blocked_lock);
761 list_for_each_entry(block, &nlm_blocked, b_list) {
762 if (nlm_compare_locks(&block->b_call->a_args.lock.fl, fl)) {
763 nlmsvc_insert_block_locked(block, 0);
764 spin_unlock(&nlm_blocked_lock);
765 svc_wake_up(block->b_daemon);
766 return;
767 }
768 }
769 spin_unlock(&nlm_blocked_lock);
770 printk(KERN_WARNING "lockd: notification for unknown block!\n");
771}
772
773static fl_owner_t nlmsvc_get_owner(fl_owner_t owner)
774{
775 return nlmsvc_get_lockowner(owner);
776}
777
778static void nlmsvc_put_owner(fl_owner_t owner)
779{
780 nlmsvc_put_lockowner(owner);
781}
782
783const struct lock_manager_operations nlmsvc_lock_operations = {
784 .lm_notify = nlmsvc_notify_blocked,
785 .lm_grant = nlmsvc_grant_deferred,
786 .lm_get_owner = nlmsvc_get_owner,
787 .lm_put_owner = nlmsvc_put_owner,
788};
789
790/*
791 * Try to claim a lock that was previously blocked.
792 *
793 * Note that we use both the RPC_GRANTED_MSG call _and_ an async
794 * RPC thread when notifying the client. This seems like overkill...
795 * Here's why:
796 * - we don't want to use a synchronous RPC thread, otherwise
797 * we might find ourselves hanging on a dead portmapper.
798 * - Some lockd implementations (e.g. HP) don't react to
799 * RPC_GRANTED calls; they seem to insist on RPC_GRANTED_MSG calls.
800 */
801static void
802nlmsvc_grant_blocked(struct nlm_block *block)
803{
804 struct nlm_file *file = block->b_file;
805 struct nlm_lock *lock = &block->b_call->a_args.lock;
806 int error;
807 loff_t fl_start, fl_end;
808
809 dprintk("lockd: grant blocked lock %p\n", block);
810
811 kref_get(&block->b_count);
812
813 /* Unlink block request from list */
814 nlmsvc_unlink_block(block);
815
816 /* If b_granted is true this means we've been here before.
817 * Just retry the grant callback, possibly refreshing the RPC
818 * binding */
819 if (block->b_granted) {
820 nlm_rebind_host(block->b_host);
821 goto callback;
822 }
823
824 /* Try the lock operation again */
825 /* vfs_lock_file() can mangle fl_start and fl_end, but we need
826 * them unchanged for the GRANT_MSG
827 */
828 lock->fl.fl_flags |= FL_SLEEP;
829 fl_start = lock->fl.fl_start;
830 fl_end = lock->fl.fl_end;
831 error = vfs_lock_file(file->f_file, F_SETLK, &lock->fl, NULL);
832 lock->fl.fl_flags &= ~FL_SLEEP;
833 lock->fl.fl_start = fl_start;
834 lock->fl.fl_end = fl_end;
835
836 switch (error) {
837 case 0:
838 break;
839 case FILE_LOCK_DEFERRED:
840 dprintk("lockd: lock still blocked error %d\n", error);
841 nlmsvc_insert_block(block, NLM_NEVER);
842 nlmsvc_release_block(block);
843 return;
844 default:
845 printk(KERN_WARNING "lockd: unexpected error %d in %s!\n",
846 -error, __func__);
847 nlmsvc_insert_block(block, 10 * HZ);
848 nlmsvc_release_block(block);
849 return;
850 }
851
852callback:
853 /* Lock was granted by VFS. */
854 dprintk("lockd: GRANTing blocked lock.\n");
855 block->b_granted = 1;
856
857 /* keep block on the list, but don't reattempt until the RPC
858 * completes or the submission fails
859 */
860 nlmsvc_insert_block(block, NLM_NEVER);
861
862 /* Call the client -- use a soft RPC task since nlmsvc_retry_blocked
863 * will queue up a new one if this one times out
864 */
865 error = nlm_async_call(block->b_call, NLMPROC_GRANTED_MSG,
866 &nlmsvc_grant_ops);
867
868 /* RPC submission failed, wait a bit and retry */
869 if (error < 0)
870 nlmsvc_insert_block(block, 10 * HZ);
871}
872
873/*
874 * This is the callback from the RPC layer when the NLM_GRANTED_MSG
875 * RPC call has succeeded or timed out.
876 * Like all RPC callbacks, it is invoked by the rpciod process, so it
877 * better not sleep. Therefore, we put the blocked lock on the nlm_blocked
878 * chain once more in order to have it removed by lockd itself (which can
879 * then sleep on the file semaphore without disrupting e.g. the nfs client).
880 */
881static void nlmsvc_grant_callback(struct rpc_task *task, void *data)
882{
883 struct nlm_rqst *call = data;
884 struct nlm_block *block = call->a_block;
885 unsigned long timeout;
886
887 dprintk("lockd: GRANT_MSG RPC callback\n");
888
889 spin_lock(&nlm_blocked_lock);
890 /* if the block is not on a list at this point then it has
891 * been invalidated. Don't try to requeue it.
892 *
893 * FIXME: it's possible that the block is removed from the list
894 * after this check but before the nlmsvc_insert_block. In that
895 * case it will be added back. Perhaps we need better locking
896 * for nlm_blocked?
897 */
898 if (list_empty(&block->b_list))
899 goto out;
900
901 /* Technically, we should down the file semaphore here. Since we
902 * move the block towards the head of the queue only, no harm
903 * can be done, though. */
904 if (task->tk_status < 0) {
905 /* RPC error: Re-insert for retransmission */
906 timeout = 10 * HZ;
907 } else {
908 /* Call was successful, now wait for client callback */
909 timeout = 60 * HZ;
910 }
911 nlmsvc_insert_block_locked(block, timeout);
912 svc_wake_up(block->b_daemon);
913out:
914 spin_unlock(&nlm_blocked_lock);
915}
916
917/*
918 * FIXME: nlmsvc_release_block() grabs a mutex. This is not allowed for an
919 * .rpc_release rpc_call_op
920 */
921static void nlmsvc_grant_release(void *data)
922{
923 struct nlm_rqst *call = data;
924 nlmsvc_release_block(call->a_block);
925}
926
927static const struct rpc_call_ops nlmsvc_grant_ops = {
928 .rpc_call_done = nlmsvc_grant_callback,
929 .rpc_release = nlmsvc_grant_release,
930};
931
932/*
933 * We received a GRANT_RES callback. Try to find the corresponding
934 * block.
935 */
936void
937nlmsvc_grant_reply(struct nlm_cookie *cookie, __be32 status)
938{
939 struct nlm_block *block;
940
941 dprintk("grant_reply: looking for cookie %x, s=%d \n",
942 *(unsigned int *)(cookie->data), status);
943 if (!(block = nlmsvc_find_block(cookie)))
944 return;
945
946 if (status == nlm_lck_denied_grace_period) {
947 /* Try again in a couple of seconds */
948 nlmsvc_insert_block(block, 10 * HZ);
949 } else {
950 /*
951 * Lock is now held by client, or has been rejected.
952 * In both cases, the block should be removed.
953 */
954 nlmsvc_unlink_block(block);
955 }
956 nlmsvc_release_block(block);
957}
958
959/* Helper function to handle retry of a deferred block.
960 * If it is a blocking lock, call grant_blocked.
961 * For a non-blocking lock or test lock, revisit the request.
962 */
963static void
964retry_deferred_block(struct nlm_block *block)
965{
966 if (!(block->b_flags & B_GOT_CALLBACK))
967 block->b_flags |= B_TIMED_OUT;
968 nlmsvc_insert_block(block, NLM_TIMEOUT);
969 dprintk("revisit block %p flags %d\n", block, block->b_flags);
970 if (block->b_deferred_req) {
971 block->b_deferred_req->revisit(block->b_deferred_req, 0);
972 block->b_deferred_req = NULL;
973 }
974}
975
976/*
977 * Retry all blocked locks that have been notified. This is where lockd
978 * picks up locks that can be granted, or grant notifications that must
979 * be retransmitted.
980 */
981unsigned long
982nlmsvc_retry_blocked(void)
983{
984 unsigned long timeout = MAX_SCHEDULE_TIMEOUT;
985 struct nlm_block *block;
986
987 spin_lock(&nlm_blocked_lock);
988 while (!list_empty(&nlm_blocked) && !kthread_should_stop()) {
989 block = list_entry(nlm_blocked.next, struct nlm_block, b_list);
990
991 if (block->b_when == NLM_NEVER)
992 break;
993 if (time_after(block->b_when, jiffies)) {
994 timeout = block->b_when - jiffies;
995 break;
996 }
997 spin_unlock(&nlm_blocked_lock);
998
999 dprintk("nlmsvc_retry_blocked(%p, when=%ld)\n",
1000 block, block->b_when);
1001 if (block->b_flags & B_QUEUED) {
1002 dprintk("nlmsvc_retry_blocked delete block (%p, granted=%d, flags=%d)\n",
1003 block, block->b_granted, block->b_flags);
1004 retry_deferred_block(block);
1005 } else
1006 nlmsvc_grant_blocked(block);
1007 spin_lock(&nlm_blocked_lock);
1008 }
1009 spin_unlock(&nlm_blocked_lock);
1010
1011 return timeout;
1012}
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * linux/fs/lockd/svclock.c
4 *
5 * Handling of server-side locks, mostly of the blocked variety.
6 * This is the ugliest part of lockd because we tread on very thin ice.
7 * GRANT and CANCEL calls may get stuck, meet in mid-flight, etc.
8 * IMNSHO introducing the grant callback into the NLM protocol was one
9 * of the worst ideas Sun ever had. Except maybe for the idea of doing
10 * NFS file locking at all.
11 *
12 * I'm trying hard to avoid race conditions by protecting most accesses
13 * to a file's list of blocked locks through a semaphore. The global
14 * list of blocked locks is not protected in this fashion however.
15 * Therefore, some functions (such as the RPC callback for the async grant
16 * call) move blocked locks towards the head of the list *while some other
17 * process might be traversing it*. This should not be a problem in
18 * practice, because this will only cause functions traversing the list
19 * to visit some blocks twice.
20 *
21 * Copyright (C) 1996, Olaf Kirch <okir@monad.swb.de>
22 */
23
24#include <linux/types.h>
25#include <linux/slab.h>
26#include <linux/errno.h>
27#include <linux/kernel.h>
28#include <linux/sched.h>
29#include <linux/sunrpc/clnt.h>
30#include <linux/sunrpc/svc_xprt.h>
31#include <linux/lockd/nlm.h>
32#include <linux/lockd/lockd.h>
33#include <linux/exportfs.h>
34
35#define NLMDBG_FACILITY NLMDBG_SVCLOCK
36
37#ifdef CONFIG_LOCKD_V4
38#define nlm_deadlock nlm4_deadlock
39#else
40#define nlm_deadlock nlm_lck_denied
41#endif
42
43static void nlmsvc_release_block(struct nlm_block *block);
44static void nlmsvc_insert_block(struct nlm_block *block, unsigned long);
45static void nlmsvc_remove_block(struct nlm_block *block);
46
47static int nlmsvc_setgrantargs(struct nlm_rqst *call, struct nlm_lock *lock);
48static void nlmsvc_freegrantargs(struct nlm_rqst *call);
49static const struct rpc_call_ops nlmsvc_grant_ops;
50
51/*
52 * The list of blocked locks to retry
53 */
54static LIST_HEAD(nlm_blocked);
55static DEFINE_SPINLOCK(nlm_blocked_lock);
56
57#if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
58static const char *nlmdbg_cookie2a(const struct nlm_cookie *cookie)
59{
60 /*
61 * We can get away with a static buffer because this is only called
62 * from lockd, which is single-threaded.
63 */
64 static char buf[2*NLM_MAXCOOKIELEN+1];
65 unsigned int i, len = sizeof(buf);
66 char *p = buf;
67
68 len--; /* allow for trailing \0 */
69 if (len < 3)
70 return "???";
71 for (i = 0 ; i < cookie->len ; i++) {
72 if (len < 2) {
73 strcpy(p-3, "...");
74 break;
75 }
76 sprintf(p, "%02x", cookie->data[i]);
77 p += 2;
78 len -= 2;
79 }
80 *p = '\0';
81
82 return buf;
83}
84#endif
85
86/*
87 * Insert a blocked lock into the global list
88 */
89static void
90nlmsvc_insert_block_locked(struct nlm_block *block, unsigned long when)
91{
92 struct nlm_block *b;
93 struct list_head *pos;
94
95 dprintk("lockd: nlmsvc_insert_block(%p, %ld)\n", block, when);
96 if (list_empty(&block->b_list)) {
97 kref_get(&block->b_count);
98 } else {
99 list_del_init(&block->b_list);
100 }
101
102 pos = &nlm_blocked;
103 if (when != NLM_NEVER) {
104 if ((when += jiffies) == NLM_NEVER)
105 when ++;
106 list_for_each(pos, &nlm_blocked) {
107 b = list_entry(pos, struct nlm_block, b_list);
108 if (time_after(b->b_when,when) || b->b_when == NLM_NEVER)
109 break;
110 }
111 /* On normal exit from the loop, pos == &nlm_blocked,
112 * so we will be adding to the end of the list - good
113 */
114 }
115
116 list_add_tail(&block->b_list, pos);
117 block->b_when = when;
118}
119
120static void nlmsvc_insert_block(struct nlm_block *block, unsigned long when)
121{
122 spin_lock(&nlm_blocked_lock);
123 nlmsvc_insert_block_locked(block, when);
124 spin_unlock(&nlm_blocked_lock);
125}
126
127/*
128 * Remove a block from the global list
129 */
130static inline void
131nlmsvc_remove_block(struct nlm_block *block)
132{
133 spin_lock(&nlm_blocked_lock);
134 if (!list_empty(&block->b_list)) {
135 list_del_init(&block->b_list);
136 spin_unlock(&nlm_blocked_lock);
137 nlmsvc_release_block(block);
138 return;
139 }
140 spin_unlock(&nlm_blocked_lock);
141}
142
143/*
144 * Find a block for a given lock
145 */
146static struct nlm_block *
147nlmsvc_lookup_block(struct nlm_file *file, struct nlm_lock *lock)
148{
149 struct nlm_block *block;
150 struct file_lock *fl;
151
152 dprintk("lockd: nlmsvc_lookup_block f=%p pd=%d %Ld-%Ld ty=%d\n",
153 file, lock->fl.c.flc_pid,
154 (long long)lock->fl.fl_start,
155 (long long)lock->fl.fl_end,
156 lock->fl.c.flc_type);
157 spin_lock(&nlm_blocked_lock);
158 list_for_each_entry(block, &nlm_blocked, b_list) {
159 fl = &block->b_call->a_args.lock.fl;
160 dprintk("lockd: check f=%p pd=%d %Ld-%Ld ty=%d cookie=%s\n",
161 block->b_file, fl->c.flc_pid,
162 (long long)fl->fl_start,
163 (long long)fl->fl_end, fl->c.flc_type,
164 nlmdbg_cookie2a(&block->b_call->a_args.cookie));
165 if (block->b_file == file && nlm_compare_locks(fl, &lock->fl)) {
166 kref_get(&block->b_count);
167 spin_unlock(&nlm_blocked_lock);
168 return block;
169 }
170 }
171 spin_unlock(&nlm_blocked_lock);
172
173 return NULL;
174}
175
176static inline int nlm_cookie_match(struct nlm_cookie *a, struct nlm_cookie *b)
177{
178 if (a->len != b->len)
179 return 0;
180 if (memcmp(a->data, b->data, a->len))
181 return 0;
182 return 1;
183}
184
185/*
186 * Find a block with a given NLM cookie.
187 */
188static inline struct nlm_block *
189nlmsvc_find_block(struct nlm_cookie *cookie)
190{
191 struct nlm_block *block;
192
193 spin_lock(&nlm_blocked_lock);
194 list_for_each_entry(block, &nlm_blocked, b_list) {
195 if (nlm_cookie_match(&block->b_call->a_args.cookie,cookie))
196 goto found;
197 }
198 spin_unlock(&nlm_blocked_lock);
199
200 return NULL;
201
202found:
203 dprintk("nlmsvc_find_block(%s): block=%p\n", nlmdbg_cookie2a(cookie), block);
204 kref_get(&block->b_count);
205 spin_unlock(&nlm_blocked_lock);
206 return block;
207}
208
209/*
210 * Create a block and initialize it.
211 *
212 * Note: we explicitly set the cookie of the grant reply to that of
213 * the blocked lock request. The spec explicitly mentions that the client
214 * should _not_ rely on the callback containing the same cookie as the
215 * request, but (as I found out later) that's because some implementations
216 * do just this. Never mind the standards comittees, they support our
217 * logging industries.
218 *
219 * 10 years later: I hope we can safely ignore these old and broken
220 * clients by now. Let's fix this so we can uniquely identify an incoming
221 * GRANTED_RES message by cookie, without having to rely on the client's IP
222 * address. --okir
223 */
224static struct nlm_block *
225nlmsvc_create_block(struct svc_rqst *rqstp, struct nlm_host *host,
226 struct nlm_file *file, struct nlm_lock *lock,
227 struct nlm_cookie *cookie)
228{
229 struct nlm_block *block;
230 struct nlm_rqst *call = NULL;
231
232 call = nlm_alloc_call(host);
233 if (call == NULL)
234 return NULL;
235
236 /* Allocate memory for block, and initialize arguments */
237 block = kzalloc(sizeof(*block), GFP_KERNEL);
238 if (block == NULL)
239 goto failed;
240 kref_init(&block->b_count);
241 INIT_LIST_HEAD(&block->b_list);
242 INIT_LIST_HEAD(&block->b_flist);
243
244 if (!nlmsvc_setgrantargs(call, lock))
245 goto failed_free;
246
247 /* Set notifier function for VFS, and init args */
248 call->a_args.lock.fl.c.flc_flags |= FL_SLEEP;
249 call->a_args.lock.fl.fl_lmops = &nlmsvc_lock_operations;
250 nlmclnt_next_cookie(&call->a_args.cookie);
251
252 dprintk("lockd: created block %p...\n", block);
253
254 /* Create and initialize the block */
255 block->b_daemon = rqstp->rq_server;
256 block->b_host = host;
257 block->b_file = file;
258 file->f_count++;
259
260 /* Add to file's list of blocks */
261 list_add(&block->b_flist, &file->f_blocks);
262
263 /* Set up RPC arguments for callback */
264 block->b_call = call;
265 call->a_flags = RPC_TASK_ASYNC;
266 call->a_block = block;
267
268 return block;
269
270failed_free:
271 kfree(block);
272failed:
273 nlmsvc_release_call(call);
274 return NULL;
275}
276
277/*
278 * Delete a block.
279 * It is the caller's responsibility to check whether the file
280 * can be closed hereafter.
281 */
282static int nlmsvc_unlink_block(struct nlm_block *block)
283{
284 int status;
285 dprintk("lockd: unlinking block %p...\n", block);
286
287 /* Remove block from list */
288 status = locks_delete_block(&block->b_call->a_args.lock.fl);
289 nlmsvc_remove_block(block);
290 return status;
291}
292
293static void nlmsvc_free_block(struct kref *kref)
294{
295 struct nlm_block *block = container_of(kref, struct nlm_block, b_count);
296 struct nlm_file *file = block->b_file;
297
298 dprintk("lockd: freeing block %p...\n", block);
299
300 /* Remove block from file's list of blocks */
301 list_del_init(&block->b_flist);
302 mutex_unlock(&file->f_mutex);
303
304 nlmsvc_freegrantargs(block->b_call);
305 nlmsvc_release_call(block->b_call);
306 nlm_release_file(block->b_file);
307 kfree(block);
308}
309
310static void nlmsvc_release_block(struct nlm_block *block)
311{
312 if (block != NULL)
313 kref_put_mutex(&block->b_count, nlmsvc_free_block, &block->b_file->f_mutex);
314}
315
316/*
317 * Loop over all blocks and delete blocks held by
318 * a matching host.
319 */
320void nlmsvc_traverse_blocks(struct nlm_host *host,
321 struct nlm_file *file,
322 nlm_host_match_fn_t match)
323{
324 struct nlm_block *block, *next;
325
326restart:
327 mutex_lock(&file->f_mutex);
328 spin_lock(&nlm_blocked_lock);
329 list_for_each_entry_safe(block, next, &file->f_blocks, b_flist) {
330 if (!match(block->b_host, host))
331 continue;
332 /* Do not destroy blocks that are not on
333 * the global retry list - why? */
334 if (list_empty(&block->b_list))
335 continue;
336 kref_get(&block->b_count);
337 spin_unlock(&nlm_blocked_lock);
338 mutex_unlock(&file->f_mutex);
339 nlmsvc_unlink_block(block);
340 nlmsvc_release_block(block);
341 goto restart;
342 }
343 spin_unlock(&nlm_blocked_lock);
344 mutex_unlock(&file->f_mutex);
345}
346
347static struct nlm_lockowner *
348nlmsvc_get_lockowner(struct nlm_lockowner *lockowner)
349{
350 refcount_inc(&lockowner->count);
351 return lockowner;
352}
353
354void nlmsvc_put_lockowner(struct nlm_lockowner *lockowner)
355{
356 if (!refcount_dec_and_lock(&lockowner->count, &lockowner->host->h_lock))
357 return;
358 list_del(&lockowner->list);
359 spin_unlock(&lockowner->host->h_lock);
360 nlmsvc_release_host(lockowner->host);
361 kfree(lockowner);
362}
363
364static struct nlm_lockowner *__nlmsvc_find_lockowner(struct nlm_host *host, pid_t pid)
365{
366 struct nlm_lockowner *lockowner;
367 list_for_each_entry(lockowner, &host->h_lockowners, list) {
368 if (lockowner->pid != pid)
369 continue;
370 return nlmsvc_get_lockowner(lockowner);
371 }
372 return NULL;
373}
374
375static struct nlm_lockowner *nlmsvc_find_lockowner(struct nlm_host *host, pid_t pid)
376{
377 struct nlm_lockowner *res, *new = NULL;
378
379 spin_lock(&host->h_lock);
380 res = __nlmsvc_find_lockowner(host, pid);
381
382 if (res == NULL) {
383 spin_unlock(&host->h_lock);
384 new = kmalloc(sizeof(*res), GFP_KERNEL);
385 spin_lock(&host->h_lock);
386 res = __nlmsvc_find_lockowner(host, pid);
387 if (res == NULL && new != NULL) {
388 res = new;
389 /* fs/locks.c will manage the refcount through lock_ops */
390 refcount_set(&new->count, 1);
391 new->pid = pid;
392 new->host = nlm_get_host(host);
393 list_add(&new->list, &host->h_lockowners);
394 new = NULL;
395 }
396 }
397
398 spin_unlock(&host->h_lock);
399 kfree(new);
400 return res;
401}
402
403void
404nlmsvc_release_lockowner(struct nlm_lock *lock)
405{
406 if (lock->fl.c.flc_owner)
407 nlmsvc_put_lockowner(lock->fl.c.flc_owner);
408}
409
410void nlmsvc_locks_init_private(struct file_lock *fl, struct nlm_host *host,
411 pid_t pid)
412{
413 fl->c.flc_owner = nlmsvc_find_lockowner(host, pid);
414}
415
416/*
417 * Initialize arguments for GRANTED call. The nlm_rqst structure
418 * has been cleared already.
419 */
420static int nlmsvc_setgrantargs(struct nlm_rqst *call, struct nlm_lock *lock)
421{
422 locks_copy_lock(&call->a_args.lock.fl, &lock->fl);
423 memcpy(&call->a_args.lock.fh, &lock->fh, sizeof(call->a_args.lock.fh));
424 call->a_args.lock.caller = utsname()->nodename;
425 call->a_args.lock.oh.len = lock->oh.len;
426
427 /* set default data area */
428 call->a_args.lock.oh.data = call->a_owner;
429 call->a_args.lock.svid = ((struct nlm_lockowner *) lock->fl.c.flc_owner)->pid;
430
431 if (lock->oh.len > NLMCLNT_OHSIZE) {
432 void *data = kmalloc(lock->oh.len, GFP_KERNEL);
433 if (!data)
434 return 0;
435 call->a_args.lock.oh.data = (u8 *) data;
436 }
437
438 memcpy(call->a_args.lock.oh.data, lock->oh.data, lock->oh.len);
439 return 1;
440}
441
442static void nlmsvc_freegrantargs(struct nlm_rqst *call)
443{
444 if (call->a_args.lock.oh.data != call->a_owner)
445 kfree(call->a_args.lock.oh.data);
446
447 locks_release_private(&call->a_args.lock.fl);
448}
449
450/*
451 * Deferred lock request handling for non-blocking lock
452 */
453static __be32
454nlmsvc_defer_lock_rqst(struct svc_rqst *rqstp, struct nlm_block *block)
455{
456 __be32 status = nlm_lck_denied_nolocks;
457
458 block->b_flags |= B_QUEUED;
459
460 nlmsvc_insert_block(block, NLM_TIMEOUT);
461
462 block->b_cache_req = &rqstp->rq_chandle;
463 if (rqstp->rq_chandle.defer) {
464 block->b_deferred_req =
465 rqstp->rq_chandle.defer(block->b_cache_req);
466 if (block->b_deferred_req != NULL)
467 status = nlm_drop_reply;
468 }
469 dprintk("lockd: nlmsvc_defer_lock_rqst block %p flags %d status %d\n",
470 block, block->b_flags, ntohl(status));
471
472 return status;
473}
474
475/*
476 * Attempt to establish a lock, and if it can't be granted, block it
477 * if required.
478 */
479__be32
480nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file,
481 struct nlm_host *host, struct nlm_lock *lock, int wait,
482 struct nlm_cookie *cookie, int reclaim)
483{
484 struct inode *inode = nlmsvc_file_inode(file);
485 struct nlm_block *block = NULL;
486 int error;
487 int mode;
488 int async_block = 0;
489 __be32 ret;
490
491 dprintk("lockd: nlmsvc_lock(%s/%ld, ty=%d, pi=%d, %Ld-%Ld, bl=%d)\n",
492 inode->i_sb->s_id, inode->i_ino,
493 lock->fl.c.flc_type,
494 lock->fl.c.flc_pid,
495 (long long)lock->fl.fl_start,
496 (long long)lock->fl.fl_end,
497 wait);
498
499 if (!exportfs_lock_op_is_async(inode->i_sb->s_export_op)) {
500 async_block = wait;
501 wait = 0;
502 }
503
504 /* Lock file against concurrent access */
505 mutex_lock(&file->f_mutex);
506 /* Get existing block (in case client is busy-waiting)
507 * or create new block
508 */
509 block = nlmsvc_lookup_block(file, lock);
510 if (block == NULL) {
511 block = nlmsvc_create_block(rqstp, host, file, lock, cookie);
512 ret = nlm_lck_denied_nolocks;
513 if (block == NULL)
514 goto out;
515 lock = &block->b_call->a_args.lock;
516 } else
517 lock->fl.c.flc_flags &= ~FL_SLEEP;
518
519 if (block->b_flags & B_QUEUED) {
520 dprintk("lockd: nlmsvc_lock deferred block %p flags %d\n",
521 block, block->b_flags);
522 if (block->b_granted) {
523 nlmsvc_unlink_block(block);
524 ret = nlm_granted;
525 goto out;
526 }
527 if (block->b_flags & B_TIMED_OUT) {
528 nlmsvc_unlink_block(block);
529 ret = nlm_lck_denied;
530 goto out;
531 }
532 ret = nlm_drop_reply;
533 goto out;
534 }
535
536 if (locks_in_grace(SVC_NET(rqstp)) && !reclaim) {
537 ret = nlm_lck_denied_grace_period;
538 goto out;
539 }
540 if (reclaim && !locks_in_grace(SVC_NET(rqstp))) {
541 ret = nlm_lck_denied_grace_period;
542 goto out;
543 }
544
545 spin_lock(&nlm_blocked_lock);
546 /*
547 * If this is a lock request for an already pending
548 * lock request we return nlm_lck_blocked without calling
549 * vfs_lock_file() again. Otherwise we have two pending
550 * requests on the underlaying ->lock() implementation but
551 * only one nlm_block to being granted by lm_grant().
552 */
553 if (exportfs_lock_op_is_async(inode->i_sb->s_export_op) &&
554 !list_empty(&block->b_list)) {
555 spin_unlock(&nlm_blocked_lock);
556 ret = nlm_lck_blocked;
557 goto out;
558 }
559
560 /* Append to list of blocked */
561 nlmsvc_insert_block_locked(block, NLM_NEVER);
562 spin_unlock(&nlm_blocked_lock);
563
564 if (!wait)
565 lock->fl.c.flc_flags &= ~FL_SLEEP;
566 mode = lock_to_openmode(&lock->fl);
567 error = vfs_lock_file(file->f_file[mode], F_SETLK, &lock->fl, NULL);
568 lock->fl.c.flc_flags &= ~FL_SLEEP;
569
570 dprintk("lockd: vfs_lock_file returned %d\n", error);
571 switch (error) {
572 case 0:
573 nlmsvc_remove_block(block);
574 ret = nlm_granted;
575 goto out;
576 case -EAGAIN:
577 if (!wait)
578 nlmsvc_remove_block(block);
579 ret = async_block ? nlm_lck_blocked : nlm_lck_denied;
580 goto out;
581 case FILE_LOCK_DEFERRED:
582 if (wait)
583 break;
584 /* Filesystem lock operation is in progress
585 Add it to the queue waiting for callback */
586 ret = nlmsvc_defer_lock_rqst(rqstp, block);
587 goto out;
588 case -EDEADLK:
589 nlmsvc_remove_block(block);
590 ret = nlm_deadlock;
591 goto out;
592 default: /* includes ENOLCK */
593 nlmsvc_remove_block(block);
594 ret = nlm_lck_denied_nolocks;
595 goto out;
596 }
597
598 ret = nlm_lck_blocked;
599out:
600 mutex_unlock(&file->f_mutex);
601 nlmsvc_release_block(block);
602 dprintk("lockd: nlmsvc_lock returned %u\n", ret);
603 return ret;
604}
605
606/*
607 * Test for presence of a conflicting lock.
608 */
609__be32
610nlmsvc_testlock(struct svc_rqst *rqstp, struct nlm_file *file,
611 struct nlm_host *host, struct nlm_lock *lock,
612 struct nlm_lock *conflock, struct nlm_cookie *cookie)
613{
614 int error;
615 int mode;
616 __be32 ret;
617
618 dprintk("lockd: nlmsvc_testlock(%s/%ld, ty=%d, %Ld-%Ld)\n",
619 nlmsvc_file_inode(file)->i_sb->s_id,
620 nlmsvc_file_inode(file)->i_ino,
621 lock->fl.c.flc_type,
622 (long long)lock->fl.fl_start,
623 (long long)lock->fl.fl_end);
624
625 if (locks_in_grace(SVC_NET(rqstp))) {
626 ret = nlm_lck_denied_grace_period;
627 goto out;
628 }
629
630 mode = lock_to_openmode(&lock->fl);
631 error = vfs_test_lock(file->f_file[mode], &lock->fl);
632 if (error) {
633 /* We can't currently deal with deferred test requests */
634 if (error == FILE_LOCK_DEFERRED)
635 WARN_ON_ONCE(1);
636
637 ret = nlm_lck_denied_nolocks;
638 goto out;
639 }
640
641 if (lock->fl.c.flc_type == F_UNLCK) {
642 ret = nlm_granted;
643 goto out;
644 }
645
646 dprintk("lockd: conflicting lock(ty=%d, %Ld-%Ld)\n",
647 lock->fl.c.flc_type, (long long)lock->fl.fl_start,
648 (long long)lock->fl.fl_end);
649 conflock->caller = "somehost"; /* FIXME */
650 conflock->len = strlen(conflock->caller);
651 conflock->oh.len = 0; /* don't return OH info */
652 conflock->svid = lock->fl.c.flc_pid;
653 conflock->fl.c.flc_type = lock->fl.c.flc_type;
654 conflock->fl.fl_start = lock->fl.fl_start;
655 conflock->fl.fl_end = lock->fl.fl_end;
656 locks_release_private(&lock->fl);
657
658 ret = nlm_lck_denied;
659out:
660 return ret;
661}
662
663/*
664 * Remove a lock.
665 * This implies a CANCEL call: We send a GRANT_MSG, the client replies
666 * with a GRANT_RES call which gets lost, and calls UNLOCK immediately
667 * afterwards. In this case the block will still be there, and hence
668 * must be removed.
669 */
670__be32
671nlmsvc_unlock(struct net *net, struct nlm_file *file, struct nlm_lock *lock)
672{
673 int error = 0;
674
675 dprintk("lockd: nlmsvc_unlock(%s/%ld, pi=%d, %Ld-%Ld)\n",
676 nlmsvc_file_inode(file)->i_sb->s_id,
677 nlmsvc_file_inode(file)->i_ino,
678 lock->fl.c.flc_pid,
679 (long long)lock->fl.fl_start,
680 (long long)lock->fl.fl_end);
681
682 /* First, cancel any lock that might be there */
683 nlmsvc_cancel_blocked(net, file, lock);
684
685 lock->fl.c.flc_type = F_UNLCK;
686 lock->fl.c.flc_file = file->f_file[O_RDONLY];
687 if (lock->fl.c.flc_file)
688 error = vfs_lock_file(lock->fl.c.flc_file, F_SETLK,
689 &lock->fl, NULL);
690 lock->fl.c.flc_file = file->f_file[O_WRONLY];
691 if (lock->fl.c.flc_file)
692 error |= vfs_lock_file(lock->fl.c.flc_file, F_SETLK,
693 &lock->fl, NULL);
694
695 return (error < 0)? nlm_lck_denied_nolocks : nlm_granted;
696}
697
698/*
699 * Cancel a previously blocked request.
700 *
701 * A cancel request always overrides any grant that may currently
702 * be in progress.
703 * The calling procedure must check whether the file can be closed.
704 */
705__be32
706nlmsvc_cancel_blocked(struct net *net, struct nlm_file *file, struct nlm_lock *lock)
707{
708 struct nlm_block *block;
709 int status = 0;
710 int mode;
711
712 dprintk("lockd: nlmsvc_cancel(%s/%ld, pi=%d, %Ld-%Ld)\n",
713 nlmsvc_file_inode(file)->i_sb->s_id,
714 nlmsvc_file_inode(file)->i_ino,
715 lock->fl.c.flc_pid,
716 (long long)lock->fl.fl_start,
717 (long long)lock->fl.fl_end);
718
719 if (locks_in_grace(net))
720 return nlm_lck_denied_grace_period;
721
722 mutex_lock(&file->f_mutex);
723 block = nlmsvc_lookup_block(file, lock);
724 mutex_unlock(&file->f_mutex);
725 if (block != NULL) {
726 struct file_lock *fl = &block->b_call->a_args.lock.fl;
727
728 mode = lock_to_openmode(fl);
729 vfs_cancel_lock(block->b_file->f_file[mode], fl);
730 status = nlmsvc_unlink_block(block);
731 nlmsvc_release_block(block);
732 }
733 return status ? nlm_lck_denied : nlm_granted;
734}
735
736/*
737 * This is a callback from the filesystem for VFS file lock requests.
738 * It will be used if lm_grant is defined and the filesystem can not
739 * respond to the request immediately.
740 * For SETLK or SETLKW request it will get the local posix lock.
741 * In all cases it will move the block to the head of nlm_blocked q where
742 * nlmsvc_retry_blocked() can send back a reply for SETLKW or revisit the
743 * deferred rpc for GETLK and SETLK.
744 */
745static void
746nlmsvc_update_deferred_block(struct nlm_block *block, int result)
747{
748 block->b_flags |= B_GOT_CALLBACK;
749 if (result == 0)
750 block->b_granted = 1;
751 else
752 block->b_flags |= B_TIMED_OUT;
753}
754
755static int nlmsvc_grant_deferred(struct file_lock *fl, int result)
756{
757 struct nlm_block *block;
758 int rc = -ENOENT;
759
760 spin_lock(&nlm_blocked_lock);
761 list_for_each_entry(block, &nlm_blocked, b_list) {
762 if (nlm_compare_locks(&block->b_call->a_args.lock.fl, fl)) {
763 dprintk("lockd: nlmsvc_notify_blocked block %p flags %d\n",
764 block, block->b_flags);
765 if (block->b_flags & B_QUEUED) {
766 if (block->b_flags & B_TIMED_OUT) {
767 rc = -ENOLCK;
768 break;
769 }
770 nlmsvc_update_deferred_block(block, result);
771 } else if (result == 0)
772 block->b_granted = 1;
773
774 nlmsvc_insert_block_locked(block, 0);
775 svc_wake_up(block->b_daemon);
776 rc = 0;
777 break;
778 }
779 }
780 spin_unlock(&nlm_blocked_lock);
781 if (rc == -ENOENT)
782 printk(KERN_WARNING "lockd: grant for unknown block\n");
783 return rc;
784}
785
786/*
787 * Unblock a blocked lock request. This is a callback invoked from the
788 * VFS layer when a lock on which we blocked is removed.
789 *
790 * This function doesn't grant the blocked lock instantly, but rather moves
791 * the block to the head of nlm_blocked where it can be picked up by lockd.
792 */
793static void
794nlmsvc_notify_blocked(struct file_lock *fl)
795{
796 struct nlm_block *block;
797
798 dprintk("lockd: VFS unblock notification for block %p\n", fl);
799 spin_lock(&nlm_blocked_lock);
800 list_for_each_entry(block, &nlm_blocked, b_list) {
801 if (nlm_compare_locks(&block->b_call->a_args.lock.fl, fl)) {
802 nlmsvc_insert_block_locked(block, 0);
803 spin_unlock(&nlm_blocked_lock);
804 svc_wake_up(block->b_daemon);
805 return;
806 }
807 }
808 spin_unlock(&nlm_blocked_lock);
809 printk(KERN_WARNING "lockd: notification for unknown block!\n");
810}
811
812static fl_owner_t nlmsvc_get_owner(fl_owner_t owner)
813{
814 return nlmsvc_get_lockowner(owner);
815}
816
817static void nlmsvc_put_owner(fl_owner_t owner)
818{
819 nlmsvc_put_lockowner(owner);
820}
821
822const struct lock_manager_operations nlmsvc_lock_operations = {
823 .lm_notify = nlmsvc_notify_blocked,
824 .lm_grant = nlmsvc_grant_deferred,
825 .lm_get_owner = nlmsvc_get_owner,
826 .lm_put_owner = nlmsvc_put_owner,
827};
828
829/*
830 * Try to claim a lock that was previously blocked.
831 *
832 * Note that we use both the RPC_GRANTED_MSG call _and_ an async
833 * RPC thread when notifying the client. This seems like overkill...
834 * Here's why:
835 * - we don't want to use a synchronous RPC thread, otherwise
836 * we might find ourselves hanging on a dead portmapper.
837 * - Some lockd implementations (e.g. HP) don't react to
838 * RPC_GRANTED calls; they seem to insist on RPC_GRANTED_MSG calls.
839 */
840static void
841nlmsvc_grant_blocked(struct nlm_block *block)
842{
843 struct nlm_file *file = block->b_file;
844 struct nlm_lock *lock = &block->b_call->a_args.lock;
845 int mode;
846 int error;
847 loff_t fl_start, fl_end;
848
849 dprintk("lockd: grant blocked lock %p\n", block);
850
851 kref_get(&block->b_count);
852
853 /* Unlink block request from list */
854 nlmsvc_unlink_block(block);
855
856 /* If b_granted is true this means we've been here before.
857 * Just retry the grant callback, possibly refreshing the RPC
858 * binding */
859 if (block->b_granted) {
860 nlm_rebind_host(block->b_host);
861 goto callback;
862 }
863
864 /* Try the lock operation again */
865 /* vfs_lock_file() can mangle fl_start and fl_end, but we need
866 * them unchanged for the GRANT_MSG
867 */
868 lock->fl.c.flc_flags |= FL_SLEEP;
869 fl_start = lock->fl.fl_start;
870 fl_end = lock->fl.fl_end;
871 mode = lock_to_openmode(&lock->fl);
872 error = vfs_lock_file(file->f_file[mode], F_SETLK, &lock->fl, NULL);
873 lock->fl.c.flc_flags &= ~FL_SLEEP;
874 lock->fl.fl_start = fl_start;
875 lock->fl.fl_end = fl_end;
876
877 switch (error) {
878 case 0:
879 break;
880 case FILE_LOCK_DEFERRED:
881 dprintk("lockd: lock still blocked error %d\n", error);
882 nlmsvc_insert_block(block, NLM_NEVER);
883 nlmsvc_release_block(block);
884 return;
885 default:
886 printk(KERN_WARNING "lockd: unexpected error %d in %s!\n",
887 -error, __func__);
888 nlmsvc_insert_block(block, 10 * HZ);
889 nlmsvc_release_block(block);
890 return;
891 }
892
893callback:
894 /* Lock was granted by VFS. */
895 dprintk("lockd: GRANTing blocked lock.\n");
896 block->b_granted = 1;
897
898 /* keep block on the list, but don't reattempt until the RPC
899 * completes or the submission fails
900 */
901 nlmsvc_insert_block(block, NLM_NEVER);
902
903 /* Call the client -- use a soft RPC task since nlmsvc_retry_blocked
904 * will queue up a new one if this one times out
905 */
906 error = nlm_async_call(block->b_call, NLMPROC_GRANTED_MSG,
907 &nlmsvc_grant_ops);
908
909 /* RPC submission failed, wait a bit and retry */
910 if (error < 0)
911 nlmsvc_insert_block(block, 10 * HZ);
912}
913
914/*
915 * This is the callback from the RPC layer when the NLM_GRANTED_MSG
916 * RPC call has succeeded or timed out.
917 * Like all RPC callbacks, it is invoked by the rpciod process, so it
918 * better not sleep. Therefore, we put the blocked lock on the nlm_blocked
919 * chain once more in order to have it removed by lockd itself (which can
920 * then sleep on the file semaphore without disrupting e.g. the nfs client).
921 */
922static void nlmsvc_grant_callback(struct rpc_task *task, void *data)
923{
924 struct nlm_rqst *call = data;
925 struct nlm_block *block = call->a_block;
926 unsigned long timeout;
927
928 dprintk("lockd: GRANT_MSG RPC callback\n");
929
930 spin_lock(&nlm_blocked_lock);
931 /* if the block is not on a list at this point then it has
932 * been invalidated. Don't try to requeue it.
933 *
934 * FIXME: it's possible that the block is removed from the list
935 * after this check but before the nlmsvc_insert_block. In that
936 * case it will be added back. Perhaps we need better locking
937 * for nlm_blocked?
938 */
939 if (list_empty(&block->b_list))
940 goto out;
941
942 /* Technically, we should down the file semaphore here. Since we
943 * move the block towards the head of the queue only, no harm
944 * can be done, though. */
945 if (task->tk_status < 0) {
946 /* RPC error: Re-insert for retransmission */
947 timeout = 10 * HZ;
948 } else {
949 /* Call was successful, now wait for client callback */
950 timeout = 60 * HZ;
951 }
952 nlmsvc_insert_block_locked(block, timeout);
953 svc_wake_up(block->b_daemon);
954out:
955 spin_unlock(&nlm_blocked_lock);
956}
957
958/*
959 * FIXME: nlmsvc_release_block() grabs a mutex. This is not allowed for an
960 * .rpc_release rpc_call_op
961 */
962static void nlmsvc_grant_release(void *data)
963{
964 struct nlm_rqst *call = data;
965 nlmsvc_release_block(call->a_block);
966}
967
968static const struct rpc_call_ops nlmsvc_grant_ops = {
969 .rpc_call_done = nlmsvc_grant_callback,
970 .rpc_release = nlmsvc_grant_release,
971};
972
973/*
974 * We received a GRANT_RES callback. Try to find the corresponding
975 * block.
976 */
977void
978nlmsvc_grant_reply(struct nlm_cookie *cookie, __be32 status)
979{
980 struct nlm_block *block;
981 struct file_lock *fl;
982 int error;
983
984 dprintk("grant_reply: looking for cookie %x, s=%d \n",
985 *(unsigned int *)(cookie->data), status);
986 if (!(block = nlmsvc_find_block(cookie)))
987 return;
988
989 switch (status) {
990 case nlm_lck_denied_grace_period:
991 /* Try again in a couple of seconds */
992 nlmsvc_insert_block(block, 10 * HZ);
993 break;
994 case nlm_lck_denied:
995 /* Client doesn't want it, just unlock it */
996 nlmsvc_unlink_block(block);
997 fl = &block->b_call->a_args.lock.fl;
998 fl->c.flc_type = F_UNLCK;
999 error = vfs_lock_file(fl->c.flc_file, F_SETLK, fl, NULL);
1000 if (error)
1001 pr_warn("lockd: unable to unlock lock rejected by client!\n");
1002 break;
1003 default:
1004 /*
1005 * Either it was accepted or the status makes no sense
1006 * just unlink it either way.
1007 */
1008 nlmsvc_unlink_block(block);
1009 }
1010 nlmsvc_release_block(block);
1011}
1012
1013/* Helper function to handle retry of a deferred block.
1014 * If it is a blocking lock, call grant_blocked.
1015 * For a non-blocking lock or test lock, revisit the request.
1016 */
1017static void
1018retry_deferred_block(struct nlm_block *block)
1019{
1020 if (!(block->b_flags & B_GOT_CALLBACK))
1021 block->b_flags |= B_TIMED_OUT;
1022 nlmsvc_insert_block(block, NLM_TIMEOUT);
1023 dprintk("revisit block %p flags %d\n", block, block->b_flags);
1024 if (block->b_deferred_req) {
1025 block->b_deferred_req->revisit(block->b_deferred_req, 0);
1026 block->b_deferred_req = NULL;
1027 }
1028}
1029
1030/*
1031 * Retry all blocked locks that have been notified. This is where lockd
1032 * picks up locks that can be granted, or grant notifications that must
1033 * be retransmitted.
1034 */
1035void
1036nlmsvc_retry_blocked(struct svc_rqst *rqstp)
1037{
1038 unsigned long timeout = MAX_SCHEDULE_TIMEOUT;
1039 struct nlm_block *block;
1040
1041 spin_lock(&nlm_blocked_lock);
1042 while (!list_empty(&nlm_blocked) && !svc_thread_should_stop(rqstp)) {
1043 block = list_entry(nlm_blocked.next, struct nlm_block, b_list);
1044
1045 if (block->b_when == NLM_NEVER)
1046 break;
1047 if (time_after(block->b_when, jiffies)) {
1048 timeout = block->b_when - jiffies;
1049 break;
1050 }
1051 spin_unlock(&nlm_blocked_lock);
1052
1053 dprintk("nlmsvc_retry_blocked(%p, when=%ld)\n",
1054 block, block->b_when);
1055 if (block->b_flags & B_QUEUED) {
1056 dprintk("nlmsvc_retry_blocked delete block (%p, granted=%d, flags=%d)\n",
1057 block, block->b_granted, block->b_flags);
1058 retry_deferred_block(block);
1059 } else
1060 nlmsvc_grant_blocked(block);
1061 spin_lock(&nlm_blocked_lock);
1062 }
1063 spin_unlock(&nlm_blocked_lock);
1064
1065 if (timeout < MAX_SCHEDULE_TIMEOUT)
1066 mod_timer(&nlmsvc_retry, jiffies + timeout);
1067}