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