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1/*
2 * linux/fs/lockd/svclock.c
3 *
4 * Handling of server-side locks, mostly of the blocked variety.
5 * This is the ugliest part of lockd because we tread on very thin ice.
6 * GRANT and CANCEL calls may get stuck, meet in mid-flight, etc.
7 * IMNSHO introducing the grant callback into the NLM protocol was one
8 * of the worst ideas Sun ever had. Except maybe for the idea of doing
9 * NFS file locking at all.
10 *
11 * I'm trying hard to avoid race conditions by protecting most accesses
12 * to a file's list of blocked locks through a semaphore. The global
13 * list of blocked locks is not protected in this fashion however.
14 * Therefore, some functions (such as the RPC callback for the async grant
15 * call) move blocked locks towards the head of the list *while some other
16 * process might be traversing it*. This should not be a problem in
17 * practice, because this will only cause functions traversing the list
18 * to visit some blocks twice.
19 *
20 * Copyright (C) 1996, Olaf Kirch <okir@monad.swb.de>
21 */
22
23#include <linux/types.h>
24#include <linux/slab.h>
25#include <linux/errno.h>
26#include <linux/kernel.h>
27#include <linux/sched.h>
28#include <linux/sunrpc/clnt.h>
29#include <linux/sunrpc/svc_xprt.h>
30#include <linux/lockd/nlm.h>
31#include <linux/lockd/lockd.h>
32#include <linux/kthread.h>
33
34#define NLMDBG_FACILITY NLMDBG_SVCLOCK
35
36#ifdef CONFIG_LOCKD_V4
37#define nlm_deadlock nlm4_deadlock
38#else
39#define nlm_deadlock nlm_lck_denied
40#endif
41
42static void nlmsvc_release_block(struct nlm_block *block);
43static void nlmsvc_insert_block(struct nlm_block *block, unsigned long);
44static void nlmsvc_remove_block(struct nlm_block *block);
45
46static int nlmsvc_setgrantargs(struct nlm_rqst *call, struct nlm_lock *lock);
47static void nlmsvc_freegrantargs(struct nlm_rqst *call);
48static const struct rpc_call_ops nlmsvc_grant_ops;
49
50/*
51 * The list of blocked locks to retry
52 */
53static LIST_HEAD(nlm_blocked);
54static DEFINE_SPINLOCK(nlm_blocked_lock);
55
56#if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
57static const char *nlmdbg_cookie2a(const struct nlm_cookie *cookie)
58{
59 /*
60 * We can get away with a static buffer because this is only called
61 * from lockd, which is single-threaded.
62 */
63 static char buf[2*NLM_MAXCOOKIELEN+1];
64 unsigned int i, len = sizeof(buf);
65 char *p = buf;
66
67 len--; /* allow for trailing \0 */
68 if (len < 3)
69 return "???";
70 for (i = 0 ; i < cookie->len ; i++) {
71 if (len < 2) {
72 strcpy(p-3, "...");
73 break;
74 }
75 sprintf(p, "%02x", cookie->data[i]);
76 p += 2;
77 len -= 2;
78 }
79 *p = '\0';
80
81 return buf;
82}
83#endif
84
85/*
86 * Insert a blocked lock into the global list
87 */
88static void
89nlmsvc_insert_block_locked(struct nlm_block *block, unsigned long when)
90{
91 struct nlm_block *b;
92 struct list_head *pos;
93
94 dprintk("lockd: nlmsvc_insert_block(%p, %ld)\n", block, when);
95 if (list_empty(&block->b_list)) {
96 kref_get(&block->b_count);
97 } else {
98 list_del_init(&block->b_list);
99 }
100
101 pos = &nlm_blocked;
102 if (when != NLM_NEVER) {
103 if ((when += jiffies) == NLM_NEVER)
104 when ++;
105 list_for_each(pos, &nlm_blocked) {
106 b = list_entry(pos, struct nlm_block, b_list);
107 if (time_after(b->b_when,when) || b->b_when == NLM_NEVER)
108 break;
109 }
110 /* On normal exit from the loop, pos == &nlm_blocked,
111 * so we will be adding to the end of the list - good
112 */
113 }
114
115 list_add_tail(&block->b_list, pos);
116 block->b_when = when;
117}
118
119static void nlmsvc_insert_block(struct nlm_block *block, unsigned long when)
120{
121 spin_lock(&nlm_blocked_lock);
122 nlmsvc_insert_block_locked(block, when);
123 spin_unlock(&nlm_blocked_lock);
124}
125
126/*
127 * Remove a block from the global list
128 */
129static inline void
130nlmsvc_remove_block(struct nlm_block *block)
131{
132 if (!list_empty(&block->b_list)) {
133 spin_lock(&nlm_blocked_lock);
134 list_del_init(&block->b_list);
135 spin_unlock(&nlm_blocked_lock);
136 nlmsvc_release_block(block);
137 }
138}
139
140/*
141 * Find a block for a given lock
142 */
143static struct nlm_block *
144nlmsvc_lookup_block(struct nlm_file *file, struct nlm_lock *lock)
145{
146 struct nlm_block *block;
147 struct file_lock *fl;
148
149 dprintk("lockd: nlmsvc_lookup_block f=%p pd=%d %Ld-%Ld ty=%d\n",
150 file, lock->fl.fl_pid,
151 (long long)lock->fl.fl_start,
152 (long long)lock->fl.fl_end, lock->fl.fl_type);
153 list_for_each_entry(block, &nlm_blocked, b_list) {
154 fl = &block->b_call->a_args.lock.fl;
155 dprintk("lockd: check f=%p pd=%d %Ld-%Ld ty=%d cookie=%s\n",
156 block->b_file, fl->fl_pid,
157 (long long)fl->fl_start,
158 (long long)fl->fl_end, fl->fl_type,
159 nlmdbg_cookie2a(&block->b_call->a_args.cookie));
160 if (block->b_file == file && nlm_compare_locks(fl, &lock->fl)) {
161 kref_get(&block->b_count);
162 return block;
163 }
164 }
165
166 return NULL;
167}
168
169static inline int nlm_cookie_match(struct nlm_cookie *a, struct nlm_cookie *b)
170{
171 if (a->len != b->len)
172 return 0;
173 if (memcmp(a->data, b->data, a->len))
174 return 0;
175 return 1;
176}
177
178/*
179 * Find a block with a given NLM cookie.
180 */
181static inline struct nlm_block *
182nlmsvc_find_block(struct nlm_cookie *cookie)
183{
184 struct nlm_block *block;
185
186 list_for_each_entry(block, &nlm_blocked, b_list) {
187 if (nlm_cookie_match(&block->b_call->a_args.cookie,cookie))
188 goto found;
189 }
190
191 return NULL;
192
193found:
194 dprintk("nlmsvc_find_block(%s): block=%p\n", nlmdbg_cookie2a(cookie), block);
195 kref_get(&block->b_count);
196 return block;
197}
198
199/*
200 * Create a block and initialize it.
201 *
202 * Note: we explicitly set the cookie of the grant reply to that of
203 * the blocked lock request. The spec explicitly mentions that the client
204 * should _not_ rely on the callback containing the same cookie as the
205 * request, but (as I found out later) that's because some implementations
206 * do just this. Never mind the standards comittees, they support our
207 * logging industries.
208 *
209 * 10 years later: I hope we can safely ignore these old and broken
210 * clients by now. Let's fix this so we can uniquely identify an incoming
211 * GRANTED_RES message by cookie, without having to rely on the client's IP
212 * address. --okir
213 */
214static struct nlm_block *
215nlmsvc_create_block(struct svc_rqst *rqstp, struct nlm_host *host,
216 struct nlm_file *file, struct nlm_lock *lock,
217 struct nlm_cookie *cookie)
218{
219 struct nlm_block *block;
220 struct nlm_rqst *call = NULL;
221
222 call = nlm_alloc_call(host);
223 if (call == NULL)
224 return NULL;
225
226 /* Allocate memory for block, and initialize arguments */
227 block = kzalloc(sizeof(*block), GFP_KERNEL);
228 if (block == NULL)
229 goto failed;
230 kref_init(&block->b_count);
231 INIT_LIST_HEAD(&block->b_list);
232 INIT_LIST_HEAD(&block->b_flist);
233
234 if (!nlmsvc_setgrantargs(call, lock))
235 goto failed_free;
236
237 /* Set notifier function for VFS, and init args */
238 call->a_args.lock.fl.fl_flags |= FL_SLEEP;
239 call->a_args.lock.fl.fl_lmops = &nlmsvc_lock_operations;
240 nlmclnt_next_cookie(&call->a_args.cookie);
241
242 dprintk("lockd: created block %p...\n", block);
243
244 /* Create and initialize the block */
245 block->b_daemon = rqstp->rq_server;
246 block->b_host = host;
247 block->b_file = file;
248 file->f_count++;
249
250 /* Add to file's list of blocks */
251 list_add(&block->b_flist, &file->f_blocks);
252
253 /* Set up RPC arguments for callback */
254 block->b_call = call;
255 call->a_flags = RPC_TASK_ASYNC;
256 call->a_block = block;
257
258 return block;
259
260failed_free:
261 kfree(block);
262failed:
263 nlmsvc_release_call(call);
264 return NULL;
265}
266
267/*
268 * Delete a block.
269 * It is the caller's responsibility to check whether the file
270 * can be closed hereafter.
271 */
272static int nlmsvc_unlink_block(struct nlm_block *block)
273{
274 int status;
275 dprintk("lockd: unlinking block %p...\n", block);
276
277 /* Remove block from list */
278 status = posix_unblock_lock(&block->b_call->a_args.lock.fl);
279 nlmsvc_remove_block(block);
280 return status;
281}
282
283static void nlmsvc_free_block(struct kref *kref)
284{
285 struct nlm_block *block = container_of(kref, struct nlm_block, b_count);
286 struct nlm_file *file = block->b_file;
287
288 dprintk("lockd: freeing block %p...\n", block);
289
290 /* Remove block from file's list of blocks */
291 list_del_init(&block->b_flist);
292 mutex_unlock(&file->f_mutex);
293
294 nlmsvc_freegrantargs(block->b_call);
295 nlmsvc_release_call(block->b_call);
296 nlm_release_file(block->b_file);
297 kfree(block);
298}
299
300static void nlmsvc_release_block(struct nlm_block *block)
301{
302 if (block != NULL)
303 kref_put_mutex(&block->b_count, nlmsvc_free_block, &block->b_file->f_mutex);
304}
305
306/*
307 * Loop over all blocks and delete blocks held by
308 * a matching host.
309 */
310void nlmsvc_traverse_blocks(struct nlm_host *host,
311 struct nlm_file *file,
312 nlm_host_match_fn_t match)
313{
314 struct nlm_block *block, *next;
315
316restart:
317 mutex_lock(&file->f_mutex);
318 list_for_each_entry_safe(block, next, &file->f_blocks, b_flist) {
319 if (!match(block->b_host, host))
320 continue;
321 /* Do not destroy blocks that are not on
322 * the global retry list - why? */
323 if (list_empty(&block->b_list))
324 continue;
325 kref_get(&block->b_count);
326 mutex_unlock(&file->f_mutex);
327 nlmsvc_unlink_block(block);
328 nlmsvc_release_block(block);
329 goto restart;
330 }
331 mutex_unlock(&file->f_mutex);
332}
333
334/*
335 * Initialize arguments for GRANTED call. The nlm_rqst structure
336 * has been cleared already.
337 */
338static int nlmsvc_setgrantargs(struct nlm_rqst *call, struct nlm_lock *lock)
339{
340 locks_copy_lock(&call->a_args.lock.fl, &lock->fl);
341 memcpy(&call->a_args.lock.fh, &lock->fh, sizeof(call->a_args.lock.fh));
342 call->a_args.lock.caller = utsname()->nodename;
343 call->a_args.lock.oh.len = lock->oh.len;
344
345 /* set default data area */
346 call->a_args.lock.oh.data = call->a_owner;
347 call->a_args.lock.svid = lock->fl.fl_pid;
348
349 if (lock->oh.len > NLMCLNT_OHSIZE) {
350 void *data = kmalloc(lock->oh.len, GFP_KERNEL);
351 if (!data)
352 return 0;
353 call->a_args.lock.oh.data = (u8 *) data;
354 }
355
356 memcpy(call->a_args.lock.oh.data, lock->oh.data, lock->oh.len);
357 return 1;
358}
359
360static void nlmsvc_freegrantargs(struct nlm_rqst *call)
361{
362 if (call->a_args.lock.oh.data != call->a_owner)
363 kfree(call->a_args.lock.oh.data);
364
365 locks_release_private(&call->a_args.lock.fl);
366}
367
368/*
369 * Deferred lock request handling for non-blocking lock
370 */
371static __be32
372nlmsvc_defer_lock_rqst(struct svc_rqst *rqstp, struct nlm_block *block)
373{
374 __be32 status = nlm_lck_denied_nolocks;
375
376 block->b_flags |= B_QUEUED;
377
378 nlmsvc_insert_block(block, NLM_TIMEOUT);
379
380 block->b_cache_req = &rqstp->rq_chandle;
381 if (rqstp->rq_chandle.defer) {
382 block->b_deferred_req =
383 rqstp->rq_chandle.defer(block->b_cache_req);
384 if (block->b_deferred_req != NULL)
385 status = nlm_drop_reply;
386 }
387 dprintk("lockd: nlmsvc_defer_lock_rqst block %p flags %d status %d\n",
388 block, block->b_flags, ntohl(status));
389
390 return status;
391}
392
393/*
394 * Attempt to establish a lock, and if it can't be granted, block it
395 * if required.
396 */
397__be32
398nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file,
399 struct nlm_host *host, struct nlm_lock *lock, int wait,
400 struct nlm_cookie *cookie, int reclaim)
401{
402 struct nlm_block *block = NULL;
403 int error;
404 __be32 ret;
405
406 dprintk("lockd: nlmsvc_lock(%s/%ld, ty=%d, pi=%d, %Ld-%Ld, bl=%d)\n",
407 file_inode(file->f_file)->i_sb->s_id,
408 file_inode(file->f_file)->i_ino,
409 lock->fl.fl_type, lock->fl.fl_pid,
410 (long long)lock->fl.fl_start,
411 (long long)lock->fl.fl_end,
412 wait);
413
414 /* Lock file against concurrent access */
415 mutex_lock(&file->f_mutex);
416 /* Get existing block (in case client is busy-waiting)
417 * or create new block
418 */
419 block = nlmsvc_lookup_block(file, lock);
420 if (block == NULL) {
421 block = nlmsvc_create_block(rqstp, host, file, lock, cookie);
422 ret = nlm_lck_denied_nolocks;
423 if (block == NULL)
424 goto out;
425 lock = &block->b_call->a_args.lock;
426 } else
427 lock->fl.fl_flags &= ~FL_SLEEP;
428
429 if (block->b_flags & B_QUEUED) {
430 dprintk("lockd: nlmsvc_lock deferred block %p flags %d\n",
431 block, block->b_flags);
432 if (block->b_granted) {
433 nlmsvc_unlink_block(block);
434 ret = nlm_granted;
435 goto out;
436 }
437 if (block->b_flags & B_TIMED_OUT) {
438 nlmsvc_unlink_block(block);
439 ret = nlm_lck_denied;
440 goto out;
441 }
442 ret = nlm_drop_reply;
443 goto out;
444 }
445
446 if (locks_in_grace(SVC_NET(rqstp)) && !reclaim) {
447 ret = nlm_lck_denied_grace_period;
448 goto out;
449 }
450 if (reclaim && !locks_in_grace(SVC_NET(rqstp))) {
451 ret = nlm_lck_denied_grace_period;
452 goto out;
453 }
454
455 if (!wait)
456 lock->fl.fl_flags &= ~FL_SLEEP;
457 error = vfs_lock_file(file->f_file, F_SETLK, &lock->fl, NULL);
458 lock->fl.fl_flags &= ~FL_SLEEP;
459
460 dprintk("lockd: vfs_lock_file returned %d\n", error);
461 switch (error) {
462 case 0:
463 ret = nlm_granted;
464 goto out;
465 case -EAGAIN:
466 /*
467 * If this is a blocking request for an
468 * already pending lock request then we need
469 * to put it back on lockd's block list
470 */
471 if (wait)
472 break;
473 ret = nlm_lck_denied;
474 goto out;
475 case FILE_LOCK_DEFERRED:
476 if (wait)
477 break;
478 /* Filesystem lock operation is in progress
479 Add it to the queue waiting for callback */
480 ret = nlmsvc_defer_lock_rqst(rqstp, block);
481 goto out;
482 case -EDEADLK:
483 ret = nlm_deadlock;
484 goto out;
485 default: /* includes ENOLCK */
486 ret = nlm_lck_denied_nolocks;
487 goto out;
488 }
489
490 ret = nlm_lck_blocked;
491
492 /* Append to list of blocked */
493 nlmsvc_insert_block(block, NLM_NEVER);
494out:
495 mutex_unlock(&file->f_mutex);
496 nlmsvc_release_block(block);
497 dprintk("lockd: nlmsvc_lock returned %u\n", ret);
498 return ret;
499}
500
501/*
502 * Test for presence of a conflicting lock.
503 */
504__be32
505nlmsvc_testlock(struct svc_rqst *rqstp, struct nlm_file *file,
506 struct nlm_host *host, struct nlm_lock *lock,
507 struct nlm_lock *conflock, struct nlm_cookie *cookie)
508{
509 int error;
510 __be32 ret;
511
512 dprintk("lockd: nlmsvc_testlock(%s/%ld, ty=%d, %Ld-%Ld)\n",
513 file_inode(file->f_file)->i_sb->s_id,
514 file_inode(file->f_file)->i_ino,
515 lock->fl.fl_type,
516 (long long)lock->fl.fl_start,
517 (long long)lock->fl.fl_end);
518
519 if (locks_in_grace(SVC_NET(rqstp))) {
520 ret = nlm_lck_denied_grace_period;
521 goto out;
522 }
523
524 error = vfs_test_lock(file->f_file, &lock->fl);
525 if (error) {
526 /* We can't currently deal with deferred test requests */
527 if (error == FILE_LOCK_DEFERRED)
528 WARN_ON_ONCE(1);
529
530 ret = nlm_lck_denied_nolocks;
531 goto out;
532 }
533
534 if (lock->fl.fl_type == F_UNLCK) {
535 ret = nlm_granted;
536 goto out;
537 }
538
539 dprintk("lockd: conflicting lock(ty=%d, %Ld-%Ld)\n",
540 lock->fl.fl_type, (long long)lock->fl.fl_start,
541 (long long)lock->fl.fl_end);
542 conflock->caller = "somehost"; /* FIXME */
543 conflock->len = strlen(conflock->caller);
544 conflock->oh.len = 0; /* don't return OH info */
545 conflock->svid = lock->fl.fl_pid;
546 conflock->fl.fl_type = lock->fl.fl_type;
547 conflock->fl.fl_start = lock->fl.fl_start;
548 conflock->fl.fl_end = lock->fl.fl_end;
549 locks_release_private(&lock->fl);
550 ret = nlm_lck_denied;
551out:
552 return ret;
553}
554
555/*
556 * Remove a lock.
557 * This implies a CANCEL call: We send a GRANT_MSG, the client replies
558 * with a GRANT_RES call which gets lost, and calls UNLOCK immediately
559 * afterwards. In this case the block will still be there, and hence
560 * must be removed.
561 */
562__be32
563nlmsvc_unlock(struct net *net, struct nlm_file *file, struct nlm_lock *lock)
564{
565 int error;
566
567 dprintk("lockd: nlmsvc_unlock(%s/%ld, pi=%d, %Ld-%Ld)\n",
568 file_inode(file->f_file)->i_sb->s_id,
569 file_inode(file->f_file)->i_ino,
570 lock->fl.fl_pid,
571 (long long)lock->fl.fl_start,
572 (long long)lock->fl.fl_end);
573
574 /* First, cancel any lock that might be there */
575 nlmsvc_cancel_blocked(net, file, lock);
576
577 lock->fl.fl_type = F_UNLCK;
578 error = vfs_lock_file(file->f_file, F_SETLK, &lock->fl, NULL);
579
580 return (error < 0)? nlm_lck_denied_nolocks : nlm_granted;
581}
582
583/*
584 * Cancel a previously blocked request.
585 *
586 * A cancel request always overrides any grant that may currently
587 * be in progress.
588 * The calling procedure must check whether the file can be closed.
589 */
590__be32
591nlmsvc_cancel_blocked(struct net *net, struct nlm_file *file, struct nlm_lock *lock)
592{
593 struct nlm_block *block;
594 int status = 0;
595
596 dprintk("lockd: nlmsvc_cancel(%s/%ld, pi=%d, %Ld-%Ld)\n",
597 file_inode(file->f_file)->i_sb->s_id,
598 file_inode(file->f_file)->i_ino,
599 lock->fl.fl_pid,
600 (long long)lock->fl.fl_start,
601 (long long)lock->fl.fl_end);
602
603 if (locks_in_grace(net))
604 return nlm_lck_denied_grace_period;
605
606 mutex_lock(&file->f_mutex);
607 block = nlmsvc_lookup_block(file, lock);
608 mutex_unlock(&file->f_mutex);
609 if (block != NULL) {
610 vfs_cancel_lock(block->b_file->f_file,
611 &block->b_call->a_args.lock.fl);
612 status = nlmsvc_unlink_block(block);
613 nlmsvc_release_block(block);
614 }
615 return status ? nlm_lck_denied : nlm_granted;
616}
617
618/*
619 * This is a callback from the filesystem for VFS file lock requests.
620 * It will be used if lm_grant is defined and the filesystem can not
621 * respond to the request immediately.
622 * For SETLK or SETLKW request it will get the local posix lock.
623 * In all cases it will move the block to the head of nlm_blocked q where
624 * nlmsvc_retry_blocked() can send back a reply for SETLKW or revisit the
625 * deferred rpc for GETLK and SETLK.
626 */
627static void
628nlmsvc_update_deferred_block(struct nlm_block *block, int result)
629{
630 block->b_flags |= B_GOT_CALLBACK;
631 if (result == 0)
632 block->b_granted = 1;
633 else
634 block->b_flags |= B_TIMED_OUT;
635}
636
637static int nlmsvc_grant_deferred(struct file_lock *fl, int result)
638{
639 struct nlm_block *block;
640 int rc = -ENOENT;
641
642 spin_lock(&nlm_blocked_lock);
643 list_for_each_entry(block, &nlm_blocked, b_list) {
644 if (nlm_compare_locks(&block->b_call->a_args.lock.fl, fl)) {
645 dprintk("lockd: nlmsvc_notify_blocked block %p flags %d\n",
646 block, block->b_flags);
647 if (block->b_flags & B_QUEUED) {
648 if (block->b_flags & B_TIMED_OUT) {
649 rc = -ENOLCK;
650 break;
651 }
652 nlmsvc_update_deferred_block(block, result);
653 } else if (result == 0)
654 block->b_granted = 1;
655
656 nlmsvc_insert_block_locked(block, 0);
657 svc_wake_up(block->b_daemon);
658 rc = 0;
659 break;
660 }
661 }
662 spin_unlock(&nlm_blocked_lock);
663 if (rc == -ENOENT)
664 printk(KERN_WARNING "lockd: grant for unknown block\n");
665 return rc;
666}
667
668/*
669 * Unblock a blocked lock request. This is a callback invoked from the
670 * VFS layer when a lock on which we blocked is removed.
671 *
672 * This function doesn't grant the blocked lock instantly, but rather moves
673 * the block to the head of nlm_blocked where it can be picked up by lockd.
674 */
675static void
676nlmsvc_notify_blocked(struct file_lock *fl)
677{
678 struct nlm_block *block;
679
680 dprintk("lockd: VFS unblock notification for block %p\n", fl);
681 spin_lock(&nlm_blocked_lock);
682 list_for_each_entry(block, &nlm_blocked, b_list) {
683 if (nlm_compare_locks(&block->b_call->a_args.lock.fl, fl)) {
684 nlmsvc_insert_block_locked(block, 0);
685 spin_unlock(&nlm_blocked_lock);
686 svc_wake_up(block->b_daemon);
687 return;
688 }
689 }
690 spin_unlock(&nlm_blocked_lock);
691 printk(KERN_WARNING "lockd: notification for unknown block!\n");
692}
693
694static int nlmsvc_same_owner(struct file_lock *fl1, struct file_lock *fl2)
695{
696 return fl1->fl_owner == fl2->fl_owner && fl1->fl_pid == fl2->fl_pid;
697}
698
699/*
700 * Since NLM uses two "keys" for tracking locks, we need to hash them down
701 * to one for the blocked_hash. Here, we're just xor'ing the host address
702 * with the pid in order to create a key value for picking a hash bucket.
703 */
704static unsigned long
705nlmsvc_owner_key(struct file_lock *fl)
706{
707 return (unsigned long)fl->fl_owner ^ (unsigned long)fl->fl_pid;
708}
709
710const struct lock_manager_operations nlmsvc_lock_operations = {
711 .lm_compare_owner = nlmsvc_same_owner,
712 .lm_owner_key = nlmsvc_owner_key,
713 .lm_notify = nlmsvc_notify_blocked,
714 .lm_grant = nlmsvc_grant_deferred,
715};
716
717/*
718 * Try to claim a lock that was previously blocked.
719 *
720 * Note that we use both the RPC_GRANTED_MSG call _and_ an async
721 * RPC thread when notifying the client. This seems like overkill...
722 * Here's why:
723 * - we don't want to use a synchronous RPC thread, otherwise
724 * we might find ourselves hanging on a dead portmapper.
725 * - Some lockd implementations (e.g. HP) don't react to
726 * RPC_GRANTED calls; they seem to insist on RPC_GRANTED_MSG calls.
727 */
728static void
729nlmsvc_grant_blocked(struct nlm_block *block)
730{
731 struct nlm_file *file = block->b_file;
732 struct nlm_lock *lock = &block->b_call->a_args.lock;
733 int error;
734 loff_t fl_start, fl_end;
735
736 dprintk("lockd: grant blocked lock %p\n", block);
737
738 kref_get(&block->b_count);
739
740 /* Unlink block request from list */
741 nlmsvc_unlink_block(block);
742
743 /* If b_granted is true this means we've been here before.
744 * Just retry the grant callback, possibly refreshing the RPC
745 * binding */
746 if (block->b_granted) {
747 nlm_rebind_host(block->b_host);
748 goto callback;
749 }
750
751 /* Try the lock operation again */
752 /* vfs_lock_file() can mangle fl_start and fl_end, but we need
753 * them unchanged for the GRANT_MSG
754 */
755 lock->fl.fl_flags |= FL_SLEEP;
756 fl_start = lock->fl.fl_start;
757 fl_end = lock->fl.fl_end;
758 error = vfs_lock_file(file->f_file, F_SETLK, &lock->fl, NULL);
759 lock->fl.fl_flags &= ~FL_SLEEP;
760 lock->fl.fl_start = fl_start;
761 lock->fl.fl_end = fl_end;
762
763 switch (error) {
764 case 0:
765 break;
766 case FILE_LOCK_DEFERRED:
767 dprintk("lockd: lock still blocked error %d\n", error);
768 nlmsvc_insert_block(block, NLM_NEVER);
769 nlmsvc_release_block(block);
770 return;
771 default:
772 printk(KERN_WARNING "lockd: unexpected error %d in %s!\n",
773 -error, __func__);
774 nlmsvc_insert_block(block, 10 * HZ);
775 nlmsvc_release_block(block);
776 return;
777 }
778
779callback:
780 /* Lock was granted by VFS. */
781 dprintk("lockd: GRANTing blocked lock.\n");
782 block->b_granted = 1;
783
784 /* keep block on the list, but don't reattempt until the RPC
785 * completes or the submission fails
786 */
787 nlmsvc_insert_block(block, NLM_NEVER);
788
789 /* Call the client -- use a soft RPC task since nlmsvc_retry_blocked
790 * will queue up a new one if this one times out
791 */
792 error = nlm_async_call(block->b_call, NLMPROC_GRANTED_MSG,
793 &nlmsvc_grant_ops);
794
795 /* RPC submission failed, wait a bit and retry */
796 if (error < 0)
797 nlmsvc_insert_block(block, 10 * HZ);
798}
799
800/*
801 * This is the callback from the RPC layer when the NLM_GRANTED_MSG
802 * RPC call has succeeded or timed out.
803 * Like all RPC callbacks, it is invoked by the rpciod process, so it
804 * better not sleep. Therefore, we put the blocked lock on the nlm_blocked
805 * chain once more in order to have it removed by lockd itself (which can
806 * then sleep on the file semaphore without disrupting e.g. the nfs client).
807 */
808static void nlmsvc_grant_callback(struct rpc_task *task, void *data)
809{
810 struct nlm_rqst *call = data;
811 struct nlm_block *block = call->a_block;
812 unsigned long timeout;
813
814 dprintk("lockd: GRANT_MSG RPC callback\n");
815
816 spin_lock(&nlm_blocked_lock);
817 /* if the block is not on a list at this point then it has
818 * been invalidated. Don't try to requeue it.
819 *
820 * FIXME: it's possible that the block is removed from the list
821 * after this check but before the nlmsvc_insert_block. In that
822 * case it will be added back. Perhaps we need better locking
823 * for nlm_blocked?
824 */
825 if (list_empty(&block->b_list))
826 goto out;
827
828 /* Technically, we should down the file semaphore here. Since we
829 * move the block towards the head of the queue only, no harm
830 * can be done, though. */
831 if (task->tk_status < 0) {
832 /* RPC error: Re-insert for retransmission */
833 timeout = 10 * HZ;
834 } else {
835 /* Call was successful, now wait for client callback */
836 timeout = 60 * HZ;
837 }
838 nlmsvc_insert_block_locked(block, timeout);
839 svc_wake_up(block->b_daemon);
840out:
841 spin_unlock(&nlm_blocked_lock);
842}
843
844/*
845 * FIXME: nlmsvc_release_block() grabs a mutex. This is not allowed for an
846 * .rpc_release rpc_call_op
847 */
848static void nlmsvc_grant_release(void *data)
849{
850 struct nlm_rqst *call = data;
851 nlmsvc_release_block(call->a_block);
852}
853
854static const struct rpc_call_ops nlmsvc_grant_ops = {
855 .rpc_call_done = nlmsvc_grant_callback,
856 .rpc_release = nlmsvc_grant_release,
857};
858
859/*
860 * We received a GRANT_RES callback. Try to find the corresponding
861 * block.
862 */
863void
864nlmsvc_grant_reply(struct nlm_cookie *cookie, __be32 status)
865{
866 struct nlm_block *block;
867
868 dprintk("grant_reply: looking for cookie %x, s=%d \n",
869 *(unsigned int *)(cookie->data), status);
870 if (!(block = nlmsvc_find_block(cookie)))
871 return;
872
873 if (block) {
874 if (status == nlm_lck_denied_grace_period) {
875 /* Try again in a couple of seconds */
876 nlmsvc_insert_block(block, 10 * HZ);
877 } else {
878 /* Lock is now held by client, or has been rejected.
879 * In both cases, the block should be removed. */
880 nlmsvc_unlink_block(block);
881 }
882 }
883 nlmsvc_release_block(block);
884}
885
886/* Helper function to handle retry of a deferred block.
887 * If it is a blocking lock, call grant_blocked.
888 * For a non-blocking lock or test lock, revisit the request.
889 */
890static void
891retry_deferred_block(struct nlm_block *block)
892{
893 if (!(block->b_flags & B_GOT_CALLBACK))
894 block->b_flags |= B_TIMED_OUT;
895 nlmsvc_insert_block(block, NLM_TIMEOUT);
896 dprintk("revisit block %p flags %d\n", block, block->b_flags);
897 if (block->b_deferred_req) {
898 block->b_deferred_req->revisit(block->b_deferred_req, 0);
899 block->b_deferred_req = NULL;
900 }
901}
902
903/*
904 * Retry all blocked locks that have been notified. This is where lockd
905 * picks up locks that can be granted, or grant notifications that must
906 * be retransmitted.
907 */
908unsigned long
909nlmsvc_retry_blocked(void)
910{
911 unsigned long timeout = MAX_SCHEDULE_TIMEOUT;
912 struct nlm_block *block;
913
914 spin_lock(&nlm_blocked_lock);
915 while (!list_empty(&nlm_blocked) && !kthread_should_stop()) {
916 block = list_entry(nlm_blocked.next, struct nlm_block, b_list);
917
918 if (block->b_when == NLM_NEVER)
919 break;
920 if (time_after(block->b_when, jiffies)) {
921 timeout = block->b_when - jiffies;
922 break;
923 }
924 spin_unlock(&nlm_blocked_lock);
925
926 dprintk("nlmsvc_retry_blocked(%p, when=%ld)\n",
927 block, block->b_when);
928 if (block->b_flags & B_QUEUED) {
929 dprintk("nlmsvc_retry_blocked delete block (%p, granted=%d, flags=%d)\n",
930 block, block->b_granted, block->b_flags);
931 retry_deferred_block(block);
932 } else
933 nlmsvc_grant_blocked(block);
934 spin_lock(&nlm_blocked_lock);
935 }
936 spin_unlock(&nlm_blocked_lock);
937
938 return timeout;
939}
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
398static void nlmsvc_locks_copy_lock(struct file_lock *new, struct file_lock *fl)
399{
400 struct nlm_lockowner *nlm_lo = (struct nlm_lockowner *)fl->fl_owner;
401 new->fl_owner = nlmsvc_get_lockowner(nlm_lo);
402}
403
404static void nlmsvc_locks_release_private(struct file_lock *fl)
405{
406 nlmsvc_put_lockowner((struct nlm_lockowner *)fl->fl_owner);
407}
408
409static const struct file_lock_operations nlmsvc_lock_ops = {
410 .fl_copy_lock = nlmsvc_locks_copy_lock,
411 .fl_release_private = nlmsvc_locks_release_private,
412};
413
414void nlmsvc_locks_init_private(struct file_lock *fl, struct nlm_host *host,
415 pid_t pid)
416{
417 fl->fl_owner = nlmsvc_find_lockowner(host, pid);
418 if (fl->fl_owner != NULL)
419 fl->fl_ops = &nlmsvc_lock_ops;
420}
421
422/*
423 * Initialize arguments for GRANTED call. The nlm_rqst structure
424 * has been cleared already.
425 */
426static int nlmsvc_setgrantargs(struct nlm_rqst *call, struct nlm_lock *lock)
427{
428 locks_copy_lock(&call->a_args.lock.fl, &lock->fl);
429 memcpy(&call->a_args.lock.fh, &lock->fh, sizeof(call->a_args.lock.fh));
430 call->a_args.lock.caller = utsname()->nodename;
431 call->a_args.lock.oh.len = lock->oh.len;
432
433 /* set default data area */
434 call->a_args.lock.oh.data = call->a_owner;
435 call->a_args.lock.svid = ((struct nlm_lockowner *)lock->fl.fl_owner)->pid;
436
437 if (lock->oh.len > NLMCLNT_OHSIZE) {
438 void *data = kmalloc(lock->oh.len, GFP_KERNEL);
439 if (!data)
440 return 0;
441 call->a_args.lock.oh.data = (u8 *) data;
442 }
443
444 memcpy(call->a_args.lock.oh.data, lock->oh.data, lock->oh.len);
445 return 1;
446}
447
448static void nlmsvc_freegrantargs(struct nlm_rqst *call)
449{
450 if (call->a_args.lock.oh.data != call->a_owner)
451 kfree(call->a_args.lock.oh.data);
452
453 locks_release_private(&call->a_args.lock.fl);
454}
455
456/*
457 * Deferred lock request handling for non-blocking lock
458 */
459static __be32
460nlmsvc_defer_lock_rqst(struct svc_rqst *rqstp, struct nlm_block *block)
461{
462 __be32 status = nlm_lck_denied_nolocks;
463
464 block->b_flags |= B_QUEUED;
465
466 nlmsvc_insert_block(block, NLM_TIMEOUT);
467
468 block->b_cache_req = &rqstp->rq_chandle;
469 if (rqstp->rq_chandle.defer) {
470 block->b_deferred_req =
471 rqstp->rq_chandle.defer(block->b_cache_req);
472 if (block->b_deferred_req != NULL)
473 status = nlm_drop_reply;
474 }
475 dprintk("lockd: nlmsvc_defer_lock_rqst block %p flags %d status %d\n",
476 block, block->b_flags, ntohl(status));
477
478 return status;
479}
480
481/*
482 * Attempt to establish a lock, and if it can't be granted, block it
483 * if required.
484 */
485__be32
486nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file,
487 struct nlm_host *host, struct nlm_lock *lock, int wait,
488 struct nlm_cookie *cookie, int reclaim)
489{
490 struct nlm_block *block = NULL;
491 int error;
492 __be32 ret;
493
494 dprintk("lockd: nlmsvc_lock(%s/%ld, ty=%d, pi=%d, %Ld-%Ld, bl=%d)\n",
495 locks_inode(file->f_file)->i_sb->s_id,
496 locks_inode(file->f_file)->i_ino,
497 lock->fl.fl_type, lock->fl.fl_pid,
498 (long long)lock->fl.fl_start,
499 (long long)lock->fl.fl_end,
500 wait);
501
502 /* Lock file against concurrent access */
503 mutex_lock(&file->f_mutex);
504 /* Get existing block (in case client is busy-waiting)
505 * or create new block
506 */
507 block = nlmsvc_lookup_block(file, lock);
508 if (block == NULL) {
509 block = nlmsvc_create_block(rqstp, host, file, lock, cookie);
510 ret = nlm_lck_denied_nolocks;
511 if (block == NULL)
512 goto out;
513 lock = &block->b_call->a_args.lock;
514 } else
515 lock->fl.fl_flags &= ~FL_SLEEP;
516
517 if (block->b_flags & B_QUEUED) {
518 dprintk("lockd: nlmsvc_lock deferred block %p flags %d\n",
519 block, block->b_flags);
520 if (block->b_granted) {
521 nlmsvc_unlink_block(block);
522 ret = nlm_granted;
523 goto out;
524 }
525 if (block->b_flags & B_TIMED_OUT) {
526 nlmsvc_unlink_block(block);
527 ret = nlm_lck_denied;
528 goto out;
529 }
530 ret = nlm_drop_reply;
531 goto out;
532 }
533
534 if (locks_in_grace(SVC_NET(rqstp)) && !reclaim) {
535 ret = nlm_lck_denied_grace_period;
536 goto out;
537 }
538 if (reclaim && !locks_in_grace(SVC_NET(rqstp))) {
539 ret = nlm_lck_denied_grace_period;
540 goto out;
541 }
542
543 if (!wait)
544 lock->fl.fl_flags &= ~FL_SLEEP;
545 error = vfs_lock_file(file->f_file, F_SETLK, &lock->fl, NULL);
546 lock->fl.fl_flags &= ~FL_SLEEP;
547
548 dprintk("lockd: vfs_lock_file returned %d\n", error);
549 switch (error) {
550 case 0:
551 ret = nlm_granted;
552 goto out;
553 case -EAGAIN:
554 /*
555 * If this is a blocking request for an
556 * already pending lock request then we need
557 * to put it back on lockd's block list
558 */
559 if (wait)
560 break;
561 ret = nlm_lck_denied;
562 goto out;
563 case FILE_LOCK_DEFERRED:
564 if (wait)
565 break;
566 /* Filesystem lock operation is in progress
567 Add it to the queue waiting for callback */
568 ret = nlmsvc_defer_lock_rqst(rqstp, block);
569 goto out;
570 case -EDEADLK:
571 ret = nlm_deadlock;
572 goto out;
573 default: /* includes ENOLCK */
574 ret = nlm_lck_denied_nolocks;
575 goto out;
576 }
577
578 ret = nlm_lck_blocked;
579
580 /* Append to list of blocked */
581 nlmsvc_insert_block(block, NLM_NEVER);
582out:
583 mutex_unlock(&file->f_mutex);
584 nlmsvc_release_block(block);
585 dprintk("lockd: nlmsvc_lock returned %u\n", ret);
586 return ret;
587}
588
589/*
590 * Test for presence of a conflicting lock.
591 */
592__be32
593nlmsvc_testlock(struct svc_rqst *rqstp, struct nlm_file *file,
594 struct nlm_host *host, struct nlm_lock *lock,
595 struct nlm_lock *conflock, struct nlm_cookie *cookie)
596{
597 int error;
598 __be32 ret;
599 struct nlm_lockowner *test_owner;
600
601 dprintk("lockd: nlmsvc_testlock(%s/%ld, ty=%d, %Ld-%Ld)\n",
602 locks_inode(file->f_file)->i_sb->s_id,
603 locks_inode(file->f_file)->i_ino,
604 lock->fl.fl_type,
605 (long long)lock->fl.fl_start,
606 (long long)lock->fl.fl_end);
607
608 if (locks_in_grace(SVC_NET(rqstp))) {
609 ret = nlm_lck_denied_grace_period;
610 goto out;
611 }
612
613 /* If there's a conflicting lock, remember to clean up the test lock */
614 test_owner = (struct nlm_lockowner *)lock->fl.fl_owner;
615
616 error = vfs_test_lock(file->f_file, &lock->fl);
617 if (error) {
618 /* We can't currently deal with deferred test requests */
619 if (error == FILE_LOCK_DEFERRED)
620 WARN_ON_ONCE(1);
621
622 ret = nlm_lck_denied_nolocks;
623 goto out;
624 }
625
626 if (lock->fl.fl_type == F_UNLCK) {
627 ret = nlm_granted;
628 goto out;
629 }
630
631 dprintk("lockd: conflicting lock(ty=%d, %Ld-%Ld)\n",
632 lock->fl.fl_type, (long long)lock->fl.fl_start,
633 (long long)lock->fl.fl_end);
634 conflock->caller = "somehost"; /* FIXME */
635 conflock->len = strlen(conflock->caller);
636 conflock->oh.len = 0; /* don't return OH info */
637 conflock->svid = ((struct nlm_lockowner *)lock->fl.fl_owner)->pid;
638 conflock->fl.fl_type = lock->fl.fl_type;
639 conflock->fl.fl_start = lock->fl.fl_start;
640 conflock->fl.fl_end = lock->fl.fl_end;
641 locks_release_private(&lock->fl);
642
643 /* Clean up the test lock */
644 lock->fl.fl_owner = NULL;
645 nlmsvc_put_lockowner(test_owner);
646
647 ret = nlm_lck_denied;
648out:
649 return ret;
650}
651
652/*
653 * Remove a lock.
654 * This implies a CANCEL call: We send a GRANT_MSG, the client replies
655 * with a GRANT_RES call which gets lost, and calls UNLOCK immediately
656 * afterwards. In this case the block will still be there, and hence
657 * must be removed.
658 */
659__be32
660nlmsvc_unlock(struct net *net, struct nlm_file *file, struct nlm_lock *lock)
661{
662 int error;
663
664 dprintk("lockd: nlmsvc_unlock(%s/%ld, pi=%d, %Ld-%Ld)\n",
665 locks_inode(file->f_file)->i_sb->s_id,
666 locks_inode(file->f_file)->i_ino,
667 lock->fl.fl_pid,
668 (long long)lock->fl.fl_start,
669 (long long)lock->fl.fl_end);
670
671 /* First, cancel any lock that might be there */
672 nlmsvc_cancel_blocked(net, file, lock);
673
674 lock->fl.fl_type = F_UNLCK;
675 error = vfs_lock_file(file->f_file, F_SETLK, &lock->fl, NULL);
676
677 return (error < 0)? nlm_lck_denied_nolocks : nlm_granted;
678}
679
680/*
681 * Cancel a previously blocked request.
682 *
683 * A cancel request always overrides any grant that may currently
684 * be in progress.
685 * The calling procedure must check whether the file can be closed.
686 */
687__be32
688nlmsvc_cancel_blocked(struct net *net, struct nlm_file *file, struct nlm_lock *lock)
689{
690 struct nlm_block *block;
691 int status = 0;
692
693 dprintk("lockd: nlmsvc_cancel(%s/%ld, pi=%d, %Ld-%Ld)\n",
694 locks_inode(file->f_file)->i_sb->s_id,
695 locks_inode(file->f_file)->i_ino,
696 lock->fl.fl_pid,
697 (long long)lock->fl.fl_start,
698 (long long)lock->fl.fl_end);
699
700 if (locks_in_grace(net))
701 return nlm_lck_denied_grace_period;
702
703 mutex_lock(&file->f_mutex);
704 block = nlmsvc_lookup_block(file, lock);
705 mutex_unlock(&file->f_mutex);
706 if (block != NULL) {
707 vfs_cancel_lock(block->b_file->f_file,
708 &block->b_call->a_args.lock.fl);
709 status = nlmsvc_unlink_block(block);
710 nlmsvc_release_block(block);
711 }
712 return status ? nlm_lck_denied : nlm_granted;
713}
714
715/*
716 * This is a callback from the filesystem for VFS file lock requests.
717 * It will be used if lm_grant is defined and the filesystem can not
718 * respond to the request immediately.
719 * For SETLK or SETLKW request it will get the local posix lock.
720 * In all cases it will move the block to the head of nlm_blocked q where
721 * nlmsvc_retry_blocked() can send back a reply for SETLKW or revisit the
722 * deferred rpc for GETLK and SETLK.
723 */
724static void
725nlmsvc_update_deferred_block(struct nlm_block *block, int result)
726{
727 block->b_flags |= B_GOT_CALLBACK;
728 if (result == 0)
729 block->b_granted = 1;
730 else
731 block->b_flags |= B_TIMED_OUT;
732}
733
734static int nlmsvc_grant_deferred(struct file_lock *fl, int result)
735{
736 struct nlm_block *block;
737 int rc = -ENOENT;
738
739 spin_lock(&nlm_blocked_lock);
740 list_for_each_entry(block, &nlm_blocked, b_list) {
741 if (nlm_compare_locks(&block->b_call->a_args.lock.fl, fl)) {
742 dprintk("lockd: nlmsvc_notify_blocked block %p flags %d\n",
743 block, block->b_flags);
744 if (block->b_flags & B_QUEUED) {
745 if (block->b_flags & B_TIMED_OUT) {
746 rc = -ENOLCK;
747 break;
748 }
749 nlmsvc_update_deferred_block(block, result);
750 } else if (result == 0)
751 block->b_granted = 1;
752
753 nlmsvc_insert_block_locked(block, 0);
754 svc_wake_up(block->b_daemon);
755 rc = 0;
756 break;
757 }
758 }
759 spin_unlock(&nlm_blocked_lock);
760 if (rc == -ENOENT)
761 printk(KERN_WARNING "lockd: grant for unknown block\n");
762 return rc;
763}
764
765/*
766 * Unblock a blocked lock request. This is a callback invoked from the
767 * VFS layer when a lock on which we blocked is removed.
768 *
769 * This function doesn't grant the blocked lock instantly, but rather moves
770 * the block to the head of nlm_blocked where it can be picked up by lockd.
771 */
772static void
773nlmsvc_notify_blocked(struct file_lock *fl)
774{
775 struct nlm_block *block;
776
777 dprintk("lockd: VFS unblock notification for block %p\n", fl);
778 spin_lock(&nlm_blocked_lock);
779 list_for_each_entry(block, &nlm_blocked, b_list) {
780 if (nlm_compare_locks(&block->b_call->a_args.lock.fl, fl)) {
781 nlmsvc_insert_block_locked(block, 0);
782 spin_unlock(&nlm_blocked_lock);
783 svc_wake_up(block->b_daemon);
784 return;
785 }
786 }
787 spin_unlock(&nlm_blocked_lock);
788 printk(KERN_WARNING "lockd: notification for unknown block!\n");
789}
790
791const struct lock_manager_operations nlmsvc_lock_operations = {
792 .lm_notify = nlmsvc_notify_blocked,
793 .lm_grant = nlmsvc_grant_deferred,
794};
795
796/*
797 * Try to claim a lock that was previously blocked.
798 *
799 * Note that we use both the RPC_GRANTED_MSG call _and_ an async
800 * RPC thread when notifying the client. This seems like overkill...
801 * Here's why:
802 * - we don't want to use a synchronous RPC thread, otherwise
803 * we might find ourselves hanging on a dead portmapper.
804 * - Some lockd implementations (e.g. HP) don't react to
805 * RPC_GRANTED calls; they seem to insist on RPC_GRANTED_MSG calls.
806 */
807static void
808nlmsvc_grant_blocked(struct nlm_block *block)
809{
810 struct nlm_file *file = block->b_file;
811 struct nlm_lock *lock = &block->b_call->a_args.lock;
812 int error;
813 loff_t fl_start, fl_end;
814
815 dprintk("lockd: grant blocked lock %p\n", block);
816
817 kref_get(&block->b_count);
818
819 /* Unlink block request from list */
820 nlmsvc_unlink_block(block);
821
822 /* If b_granted is true this means we've been here before.
823 * Just retry the grant callback, possibly refreshing the RPC
824 * binding */
825 if (block->b_granted) {
826 nlm_rebind_host(block->b_host);
827 goto callback;
828 }
829
830 /* Try the lock operation again */
831 /* vfs_lock_file() can mangle fl_start and fl_end, but we need
832 * them unchanged for the GRANT_MSG
833 */
834 lock->fl.fl_flags |= FL_SLEEP;
835 fl_start = lock->fl.fl_start;
836 fl_end = lock->fl.fl_end;
837 error = vfs_lock_file(file->f_file, F_SETLK, &lock->fl, NULL);
838 lock->fl.fl_flags &= ~FL_SLEEP;
839 lock->fl.fl_start = fl_start;
840 lock->fl.fl_end = fl_end;
841
842 switch (error) {
843 case 0:
844 break;
845 case FILE_LOCK_DEFERRED:
846 dprintk("lockd: lock still blocked error %d\n", error);
847 nlmsvc_insert_block(block, NLM_NEVER);
848 nlmsvc_release_block(block);
849 return;
850 default:
851 printk(KERN_WARNING "lockd: unexpected error %d in %s!\n",
852 -error, __func__);
853 nlmsvc_insert_block(block, 10 * HZ);
854 nlmsvc_release_block(block);
855 return;
856 }
857
858callback:
859 /* Lock was granted by VFS. */
860 dprintk("lockd: GRANTing blocked lock.\n");
861 block->b_granted = 1;
862
863 /* keep block on the list, but don't reattempt until the RPC
864 * completes or the submission fails
865 */
866 nlmsvc_insert_block(block, NLM_NEVER);
867
868 /* Call the client -- use a soft RPC task since nlmsvc_retry_blocked
869 * will queue up a new one if this one times out
870 */
871 error = nlm_async_call(block->b_call, NLMPROC_GRANTED_MSG,
872 &nlmsvc_grant_ops);
873
874 /* RPC submission failed, wait a bit and retry */
875 if (error < 0)
876 nlmsvc_insert_block(block, 10 * HZ);
877}
878
879/*
880 * This is the callback from the RPC layer when the NLM_GRANTED_MSG
881 * RPC call has succeeded or timed out.
882 * Like all RPC callbacks, it is invoked by the rpciod process, so it
883 * better not sleep. Therefore, we put the blocked lock on the nlm_blocked
884 * chain once more in order to have it removed by lockd itself (which can
885 * then sleep on the file semaphore without disrupting e.g. the nfs client).
886 */
887static void nlmsvc_grant_callback(struct rpc_task *task, void *data)
888{
889 struct nlm_rqst *call = data;
890 struct nlm_block *block = call->a_block;
891 unsigned long timeout;
892
893 dprintk("lockd: GRANT_MSG RPC callback\n");
894
895 spin_lock(&nlm_blocked_lock);
896 /* if the block is not on a list at this point then it has
897 * been invalidated. Don't try to requeue it.
898 *
899 * FIXME: it's possible that the block is removed from the list
900 * after this check but before the nlmsvc_insert_block. In that
901 * case it will be added back. Perhaps we need better locking
902 * for nlm_blocked?
903 */
904 if (list_empty(&block->b_list))
905 goto out;
906
907 /* Technically, we should down the file semaphore here. Since we
908 * move the block towards the head of the queue only, no harm
909 * can be done, though. */
910 if (task->tk_status < 0) {
911 /* RPC error: Re-insert for retransmission */
912 timeout = 10 * HZ;
913 } else {
914 /* Call was successful, now wait for client callback */
915 timeout = 60 * HZ;
916 }
917 nlmsvc_insert_block_locked(block, timeout);
918 svc_wake_up(block->b_daemon);
919out:
920 spin_unlock(&nlm_blocked_lock);
921}
922
923/*
924 * FIXME: nlmsvc_release_block() grabs a mutex. This is not allowed for an
925 * .rpc_release rpc_call_op
926 */
927static void nlmsvc_grant_release(void *data)
928{
929 struct nlm_rqst *call = data;
930 nlmsvc_release_block(call->a_block);
931}
932
933static const struct rpc_call_ops nlmsvc_grant_ops = {
934 .rpc_call_done = nlmsvc_grant_callback,
935 .rpc_release = nlmsvc_grant_release,
936};
937
938/*
939 * We received a GRANT_RES callback. Try to find the corresponding
940 * block.
941 */
942void
943nlmsvc_grant_reply(struct nlm_cookie *cookie, __be32 status)
944{
945 struct nlm_block *block;
946
947 dprintk("grant_reply: looking for cookie %x, s=%d \n",
948 *(unsigned int *)(cookie->data), status);
949 if (!(block = nlmsvc_find_block(cookie)))
950 return;
951
952 if (status == nlm_lck_denied_grace_period) {
953 /* Try again in a couple of seconds */
954 nlmsvc_insert_block(block, 10 * HZ);
955 } else {
956 /*
957 * Lock is now held by client, or has been rejected.
958 * In both cases, the block should be removed.
959 */
960 nlmsvc_unlink_block(block);
961 }
962 nlmsvc_release_block(block);
963}
964
965/* Helper function to handle retry of a deferred block.
966 * If it is a blocking lock, call grant_blocked.
967 * For a non-blocking lock or test lock, revisit the request.
968 */
969static void
970retry_deferred_block(struct nlm_block *block)
971{
972 if (!(block->b_flags & B_GOT_CALLBACK))
973 block->b_flags |= B_TIMED_OUT;
974 nlmsvc_insert_block(block, NLM_TIMEOUT);
975 dprintk("revisit block %p flags %d\n", block, block->b_flags);
976 if (block->b_deferred_req) {
977 block->b_deferred_req->revisit(block->b_deferred_req, 0);
978 block->b_deferred_req = NULL;
979 }
980}
981
982/*
983 * Retry all blocked locks that have been notified. This is where lockd
984 * picks up locks that can be granted, or grant notifications that must
985 * be retransmitted.
986 */
987unsigned long
988nlmsvc_retry_blocked(void)
989{
990 unsigned long timeout = MAX_SCHEDULE_TIMEOUT;
991 struct nlm_block *block;
992
993 spin_lock(&nlm_blocked_lock);
994 while (!list_empty(&nlm_blocked) && !kthread_should_stop()) {
995 block = list_entry(nlm_blocked.next, struct nlm_block, b_list);
996
997 if (block->b_when == NLM_NEVER)
998 break;
999 if (time_after(block->b_when, jiffies)) {
1000 timeout = block->b_when - jiffies;
1001 break;
1002 }
1003 spin_unlock(&nlm_blocked_lock);
1004
1005 dprintk("nlmsvc_retry_blocked(%p, when=%ld)\n",
1006 block, block->b_when);
1007 if (block->b_flags & B_QUEUED) {
1008 dprintk("nlmsvc_retry_blocked delete block (%p, granted=%d, flags=%d)\n",
1009 block, block->b_granted, block->b_flags);
1010 retry_deferred_block(block);
1011 } else
1012 nlmsvc_grant_blocked(block);
1013 spin_lock(&nlm_blocked_lock);
1014 }
1015 spin_unlock(&nlm_blocked_lock);
1016
1017 return timeout;
1018}