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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/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
331 /*
332 * Deferred lock request handling for non-blocking lock
333 */
334 static __be32
335 nlmsvc_defer_lock_rqst(struct svc_rqst *rqstp, struct nlm_block *block)
336 {
337 __be32 status = nlm_lck_denied_nolocks;
338
339 block->b_flags |= B_QUEUED;
340
341 nlmsvc_insert_block(block, NLM_TIMEOUT);
342
343 block->b_cache_req = &rqstp->rq_chandle;
344 if (rqstp->rq_chandle.defer) {
345 block->b_deferred_req =
346 rqstp->rq_chandle.defer(block->b_cache_req);
347 if (block->b_deferred_req != NULL)
348 status = nlm_drop_reply;
349 }
350 dprintk("lockd: nlmsvc_defer_lock_rqst block %p flags %d status %d\n",
351 block, block->b_flags, ntohl(status));
352
353 return status;
354 }
355
356 /*
357 * Attempt to establish a lock, and if it can't be granted, block it
358 * if required.
359 */
360 __be32
361 nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file,
362 struct nlm_host *host, struct nlm_lock *lock, int wait,
363 struct nlm_cookie *cookie, int reclaim)
364 {
365 struct nlm_block *block = NULL;
366 int error;
367 __be32 ret;
368
369 dprintk("lockd: nlmsvc_lock(%s/%ld, ty=%d, pi=%d, %Ld-%Ld, bl=%d)\n",
370 file->f_file->f_path.dentry->d_inode->i_sb->s_id,
371 file->f_file->f_path.dentry->d_inode->i_ino,
372 lock->fl.fl_type, lock->fl.fl_pid,
373 (long long)lock->fl.fl_start,
374 (long long)lock->fl.fl_end,
375 wait);
376
377 /* Lock file against concurrent access */
378 mutex_lock(&file->f_mutex);
379 /* Get existing block (in case client is busy-waiting)
380 * or create new block
381 */
382 block = nlmsvc_lookup_block(file, lock);
383 if (block == NULL) {
384 block = nlmsvc_create_block(rqstp, host, file, lock, cookie);
385 ret = nlm_lck_denied_nolocks;
386 if (block == NULL)
387 goto out;
388 lock = &block->b_call->a_args.lock;
389 } else
390 lock->fl.fl_flags &= ~FL_SLEEP;
391
392 if (block->b_flags & B_QUEUED) {
393 dprintk("lockd: nlmsvc_lock deferred block %p flags %d\n",
394 block, block->b_flags);
395 if (block->b_granted) {
396 nlmsvc_unlink_block(block);
397 ret = nlm_granted;
398 goto out;
399 }
400 if (block->b_flags & B_TIMED_OUT) {
401 nlmsvc_unlink_block(block);
402 ret = nlm_lck_denied;
403 goto out;
404 }
405 ret = nlm_drop_reply;
406 goto out;
407 }
408
409 if (locks_in_grace() && !reclaim) {
410 ret = nlm_lck_denied_grace_period;
411 goto out;
412 }
413 if (reclaim && !locks_in_grace()) {
414 ret = nlm_lck_denied_grace_period;
415 goto out;
416 }
417
418 if (!wait)
419 lock->fl.fl_flags &= ~FL_SLEEP;
420 error = vfs_lock_file(file->f_file, F_SETLK, &lock->fl, NULL);
421 lock->fl.fl_flags &= ~FL_SLEEP;
422
423 dprintk("lockd: vfs_lock_file returned %d\n", error);
424 switch (error) {
425 case 0:
426 ret = nlm_granted;
427 goto out;
428 case -EAGAIN:
429 /*
430 * If this is a blocking request for an
431 * already pending lock request then we need
432 * to put it back on lockd's block list
433 */
434 if (wait)
435 break;
436 ret = nlm_lck_denied;
437 goto out;
438 case FILE_LOCK_DEFERRED:
439 if (wait)
440 break;
441 /* Filesystem lock operation is in progress
442 Add it to the queue waiting for callback */
443 ret = nlmsvc_defer_lock_rqst(rqstp, block);
444 goto out;
445 case -EDEADLK:
446 ret = nlm_deadlock;
447 goto out;
448 default: /* includes ENOLCK */
449 ret = nlm_lck_denied_nolocks;
450 goto out;
451 }
452
453 ret = nlm_lck_blocked;
454
455 /* Append to list of blocked */
456 nlmsvc_insert_block(block, NLM_NEVER);
457 out:
458 mutex_unlock(&file->f_mutex);
459 nlmsvc_release_block(block);
460 dprintk("lockd: nlmsvc_lock returned %u\n", ret);
461 return ret;
462 }
463
464 /*
465 * Test for presence of a conflicting lock.
466 */
467 __be32
468 nlmsvc_testlock(struct svc_rqst *rqstp, struct nlm_file *file,
469 struct nlm_host *host, struct nlm_lock *lock,
470 struct nlm_lock *conflock, struct nlm_cookie *cookie)
471 {
472 struct nlm_block *block = NULL;
473 int error;
474 __be32 ret;
475
476 dprintk("lockd: nlmsvc_testlock(%s/%ld, ty=%d, %Ld-%Ld)\n",
477 file->f_file->f_path.dentry->d_inode->i_sb->s_id,
478 file->f_file->f_path.dentry->d_inode->i_ino,
479 lock->fl.fl_type,
480 (long long)lock->fl.fl_start,
481 (long long)lock->fl.fl_end);
482
483 /* Get existing block (in case client is busy-waiting) */
484 block = nlmsvc_lookup_block(file, lock);
485
486 if (block == NULL) {
487 struct file_lock *conf = kzalloc(sizeof(*conf), GFP_KERNEL);
488
489 if (conf == NULL)
490 return nlm_granted;
491 block = nlmsvc_create_block(rqstp, host, file, lock, cookie);
492 if (block == NULL) {
493 kfree(conf);
494 return nlm_granted;
495 }
496 block->b_fl = conf;
497 }
498 if (block->b_flags & B_QUEUED) {
499 dprintk("lockd: nlmsvc_testlock deferred block %p flags %d fl %p\n",
500 block, block->b_flags, block->b_fl);
501 if (block->b_flags & B_TIMED_OUT) {
502 nlmsvc_unlink_block(block);
503 ret = nlm_lck_denied;
504 goto out;
505 }
506 if (block->b_flags & B_GOT_CALLBACK) {
507 nlmsvc_unlink_block(block);
508 if (block->b_fl != NULL
509 && block->b_fl->fl_type != F_UNLCK) {
510 lock->fl = *block->b_fl;
511 goto conf_lock;
512 } else {
513 ret = nlm_granted;
514 goto out;
515 }
516 }
517 ret = nlm_drop_reply;
518 goto out;
519 }
520
521 if (locks_in_grace()) {
522 ret = nlm_lck_denied_grace_period;
523 goto out;
524 }
525 error = vfs_test_lock(file->f_file, &lock->fl);
526 if (error == FILE_LOCK_DEFERRED) {
527 ret = nlmsvc_defer_lock_rqst(rqstp, block);
528 goto out;
529 }
530 if (error) {
531 ret = nlm_lck_denied_nolocks;
532 goto out;
533 }
534 if (lock->fl.fl_type == F_UNLCK) {
535 ret = nlm_granted;
536 goto out;
537 }
538
539 conf_lock:
540 dprintk("lockd: conflicting lock(ty=%d, %Ld-%Ld)\n",
541 lock->fl.fl_type, (long long)lock->fl.fl_start,
542 (long long)lock->fl.fl_end);
543 conflock->caller = "somehost"; /* FIXME */
544 conflock->len = strlen(conflock->caller);
545 conflock->oh.len = 0; /* don't return OH info */
546 conflock->svid = lock->fl.fl_pid;
547 conflock->fl.fl_type = lock->fl.fl_type;
548 conflock->fl.fl_start = lock->fl.fl_start;
549 conflock->fl.fl_end = lock->fl.fl_end;
550 ret = nlm_lck_denied;
551 out:
552 if (block)
553 nlmsvc_release_block(block);
554 return ret;
555 }
556
557 /*
558 * Remove a lock.
559 * This implies a CANCEL call: We send a GRANT_MSG, the client replies
560 * with a GRANT_RES call which gets lost, and calls UNLOCK immediately
561 * afterwards. In this case the block will still be there, and hence
562 * must be removed.
563 */
564 __be32
565 nlmsvc_unlock(struct nlm_file *file, struct nlm_lock *lock)
566 {
567 int error;
568
569 dprintk("lockd: nlmsvc_unlock(%s/%ld, pi=%d, %Ld-%Ld)\n",
570 file->f_file->f_path.dentry->d_inode->i_sb->s_id,
571 file->f_file->f_path.dentry->d_inode->i_ino,
572 lock->fl.fl_pid,
573 (long long)lock->fl.fl_start,
574 (long long)lock->fl.fl_end);
575
576 /* First, cancel any lock that might be there */
577 nlmsvc_cancel_blocked(file, lock);
578
579 lock->fl.fl_type = F_UNLCK;
580 error = vfs_lock_file(file->f_file, F_SETLK, &lock->fl, NULL);
581
582 return (error < 0)? nlm_lck_denied_nolocks : nlm_granted;
583 }
584
585 /*
586 * Cancel a previously blocked request.
587 *
588 * A cancel request always overrides any grant that may currently
589 * be in progress.
590 * The calling procedure must check whether the file can be closed.
591 */
592 __be32
593 nlmsvc_cancel_blocked(struct nlm_file *file, struct nlm_lock *lock)
594 {
595 struct nlm_block *block;
596 int status = 0;
597
598 dprintk("lockd: nlmsvc_cancel(%s/%ld, pi=%d, %Ld-%Ld)\n",
599 file->f_file->f_path.dentry->d_inode->i_sb->s_id,
600 file->f_file->f_path.dentry->d_inode->i_ino,
601 lock->fl.fl_pid,
602 (long long)lock->fl.fl_start,
603 (long long)lock->fl.fl_end);
604
605 if (locks_in_grace())
606 return nlm_lck_denied_grace_period;
607
608 mutex_lock(&file->f_mutex);
609 block = nlmsvc_lookup_block(file, lock);
610 mutex_unlock(&file->f_mutex);
611 if (block != NULL) {
612 vfs_cancel_lock(block->b_file->f_file,
613 &block->b_call->a_args.lock.fl);
614 status = nlmsvc_unlink_block(block);
615 nlmsvc_release_block(block);
616 }
617 return status ? nlm_lck_denied : nlm_granted;
618 }
619
620 /*
621 * This is a callback from the filesystem for VFS file lock requests.
622 * It will be used if fl_grant is defined and the filesystem can not
623 * respond to the request immediately.
624 * For GETLK request it will copy the reply to the nlm_block.
625 * For SETLK or SETLKW request it will get the local posix lock.
626 * In all cases it will move the block to the head of nlm_blocked q where
627 * nlmsvc_retry_blocked() can send back a reply for SETLKW or revisit the
628 * deferred rpc for GETLK and SETLK.
629 */
630 static void
631 nlmsvc_update_deferred_block(struct nlm_block *block, struct file_lock *conf,
632 int result)
633 {
634 block->b_flags |= B_GOT_CALLBACK;
635 if (result == 0)
636 block->b_granted = 1;
637 else
638 block->b_flags |= B_TIMED_OUT;
639 if (conf) {
640 if (block->b_fl)
641 __locks_copy_lock(block->b_fl, conf);
642 }
643 }
644
645 static int nlmsvc_grant_deferred(struct file_lock *fl, struct file_lock *conf,
646 int result)
647 {
648 struct nlm_block *block;
649 int rc = -ENOENT;
650
651 lock_kernel();
652 list_for_each_entry(block, &nlm_blocked, b_list) {
653 if (nlm_compare_locks(&block->b_call->a_args.lock.fl, fl)) {
654 dprintk("lockd: nlmsvc_notify_blocked block %p flags %d\n",
655 block, block->b_flags);
656 if (block->b_flags & B_QUEUED) {
657 if (block->b_flags & B_TIMED_OUT) {
658 rc = -ENOLCK;
659 break;
660 }
661 nlmsvc_update_deferred_block(block, conf, result);
662 } else if (result == 0)
663 block->b_granted = 1;
664
665 nlmsvc_insert_block(block, 0);
666 svc_wake_up(block->b_daemon);
667 rc = 0;
668 break;
669 }
670 }
671 unlock_kernel();
672 if (rc == -ENOENT)
673 printk(KERN_WARNING "lockd: grant for unknown block\n");
674 return rc;
675 }
676
677 /*
678 * Unblock a blocked lock request. This is a callback invoked from the
679 * VFS layer when a lock on which we blocked is removed.
680 *
681 * This function doesn't grant the blocked lock instantly, but rather moves
682 * the block to the head of nlm_blocked where it can be picked up by lockd.
683 */
684 static void
685 nlmsvc_notify_blocked(struct file_lock *fl)
686 {
687 struct nlm_block *block;
688
689 dprintk("lockd: VFS unblock notification for block %p\n", fl);
690 list_for_each_entry(block, &nlm_blocked, b_list) {
691 if (nlm_compare_locks(&block->b_call->a_args.lock.fl, fl)) {
692 nlmsvc_insert_block(block, 0);
693 svc_wake_up(block->b_daemon);
694 return;
695 }
696 }
697
698 printk(KERN_WARNING "lockd: notification for unknown block!\n");
699 }
700
701 static int nlmsvc_same_owner(struct file_lock *fl1, struct file_lock *fl2)
702 {
703 return fl1->fl_owner == fl2->fl_owner && fl1->fl_pid == fl2->fl_pid;
704 }
705
706 struct lock_manager_operations nlmsvc_lock_operations = {
707 .fl_compare_owner = nlmsvc_same_owner,
708 .fl_notify = nlmsvc_notify_blocked,
709 .fl_grant = nlmsvc_grant_deferred,
710 };
711
712 /*
713 * Try to claim a lock that was previously blocked.
714 *
715 * Note that we use both the RPC_GRANTED_MSG call _and_ an async
716 * RPC thread when notifying the client. This seems like overkill...
717 * Here's why:
718 * - we don't want to use a synchronous RPC thread, otherwise
719 * we might find ourselves hanging on a dead portmapper.
720 * - Some lockd implementations (e.g. HP) don't react to
721 * RPC_GRANTED calls; they seem to insist on RPC_GRANTED_MSG calls.
722 */
723 static void
724 nlmsvc_grant_blocked(struct nlm_block *block)
725 {
726 struct nlm_file *file = block->b_file;
727 struct nlm_lock *lock = &block->b_call->a_args.lock;
728 int error;
729
730 dprintk("lockd: grant blocked lock %p\n", block);
731
732 kref_get(&block->b_count);
733
734 /* Unlink block request from list */
735 nlmsvc_unlink_block(block);
736
737 /* If b_granted is true this means we've been here before.
738 * Just retry the grant callback, possibly refreshing the RPC
739 * binding */
740 if (block->b_granted) {
741 nlm_rebind_host(block->b_host);
742 goto callback;
743 }
744
745 /* Try the lock operation again */
746 lock->fl.fl_flags |= FL_SLEEP;
747 error = vfs_lock_file(file->f_file, F_SETLK, &lock->fl, NULL);
748 lock->fl.fl_flags &= ~FL_SLEEP;
749
750 switch (error) {
751 case 0:
752 break;
753 case FILE_LOCK_DEFERRED:
754 dprintk("lockd: lock still blocked error %d\n", error);
755 nlmsvc_insert_block(block, NLM_NEVER);
756 nlmsvc_release_block(block);
757 return;
758 default:
759 printk(KERN_WARNING "lockd: unexpected error %d in %s!\n",
760 -error, __func__);
761 nlmsvc_insert_block(block, 10 * HZ);
762 nlmsvc_release_block(block);
763 return;
764 }
765
766 callback:
767 /* Lock was granted by VFS. */
768 dprintk("lockd: GRANTing blocked lock.\n");
769 block->b_granted = 1;
770
771 /* keep block on the list, but don't reattempt until the RPC
772 * completes or the submission fails
773 */
774 nlmsvc_insert_block(block, NLM_NEVER);
775
776 /* Call the client -- use a soft RPC task since nlmsvc_retry_blocked
777 * will queue up a new one if this one times out
778 */
779 error = nlm_async_call(block->b_call, NLMPROC_GRANTED_MSG,
780 &nlmsvc_grant_ops);
781
782 /* RPC submission failed, wait a bit and retry */
783 if (error < 0)
784 nlmsvc_insert_block(block, 10 * HZ);
785 }
786
787 /*
788 * This is the callback from the RPC layer when the NLM_GRANTED_MSG
789 * RPC call has succeeded or timed out.
790 * Like all RPC callbacks, it is invoked by the rpciod process, so it
791 * better not sleep. Therefore, we put the blocked lock on the nlm_blocked
792 * chain once more in order to have it removed by lockd itself (which can
793 * then sleep on the file semaphore without disrupting e.g. the nfs client).
794 */
795 static void nlmsvc_grant_callback(struct rpc_task *task, void *data)
796 {
797 struct nlm_rqst *call = data;
798 struct nlm_block *block = call->a_block;
799 unsigned long timeout;
800
801 dprintk("lockd: GRANT_MSG RPC callback\n");
802
803 lock_kernel();
804 /* if the block is not on a list at this point then it has
805 * been invalidated. Don't try to requeue it.
806 *
807 * FIXME: it's possible that the block is removed from the list
808 * after this check but before the nlmsvc_insert_block. In that
809 * case it will be added back. Perhaps we need better locking
810 * for nlm_blocked?
811 */
812 if (list_empty(&block->b_list))
813 goto out;
814
815 /* Technically, we should down the file semaphore here. Since we
816 * move the block towards the head of the queue only, no harm
817 * can be done, though. */
818 if (task->tk_status < 0) {
819 /* RPC error: Re-insert for retransmission */
820 timeout = 10 * HZ;
821 } else {
822 /* Call was successful, now wait for client callback */
823 timeout = 60 * HZ;
824 }
825 nlmsvc_insert_block(block, timeout);
826 svc_wake_up(block->b_daemon);
827 out:
828 unlock_kernel();
829 }
830
831 static void nlmsvc_grant_release(void *data)
832 {
833 struct nlm_rqst *call = data;
834
835 lock_kernel();
836 nlmsvc_release_block(call->a_block);
837 unlock_kernel();
838 }
839
840 static const struct rpc_call_ops nlmsvc_grant_ops = {
841 .rpc_call_done = nlmsvc_grant_callback,
842 .rpc_release = nlmsvc_grant_release,
843 };
844
845 /*
846 * We received a GRANT_RES callback. Try to find the corresponding
847 * block.
848 */
849 void
850 nlmsvc_grant_reply(struct nlm_cookie *cookie, __be32 status)
851 {
852 struct nlm_block *block;
853
854 dprintk("grant_reply: looking for cookie %x, s=%d \n",
855 *(unsigned int *)(cookie->data), status);
856 if (!(block = nlmsvc_find_block(cookie)))
857 return;
858
859 if (block) {
860 if (status == nlm_lck_denied_grace_period) {
861 /* Try again in a couple of seconds */
862 nlmsvc_insert_block(block, 10 * HZ);
863 } else {
864 /* Lock is now held by client, or has been rejected.
865 * In both cases, the block should be removed. */
866 nlmsvc_unlink_block(block);
867 }
868 }
869 nlmsvc_release_block(block);
870 }
871
872 /* Helper function to handle retry of a deferred block.
873 * If it is a blocking lock, call grant_blocked.
874 * For a non-blocking lock or test lock, revisit the request.
875 */
876 static void
877 retry_deferred_block(struct nlm_block *block)
878 {
879 if (!(block->b_flags & B_GOT_CALLBACK))
880 block->b_flags |= B_TIMED_OUT;
881 nlmsvc_insert_block(block, NLM_TIMEOUT);
882 dprintk("revisit block %p flags %d\n", block, block->b_flags);
883 if (block->b_deferred_req) {
884 block->b_deferred_req->revisit(block->b_deferred_req, 0);
885 block->b_deferred_req = NULL;
886 }
887 }
888
889 /*
890 * Retry all blocked locks that have been notified. This is where lockd
891 * picks up locks that can be granted, or grant notifications that must
892 * be retransmitted.
893 */
894 unsigned long
895 nlmsvc_retry_blocked(void)
896 {
897 unsigned long timeout = MAX_SCHEDULE_TIMEOUT;
898 struct nlm_block *block;
899
900 while (!list_empty(&nlm_blocked) && !kthread_should_stop()) {
901 block = list_entry(nlm_blocked.next, struct nlm_block, b_list);
902
903 if (block->b_when == NLM_NEVER)
904 break;
905 if (time_after(block->b_when, jiffies)) {
906 timeout = block->b_when - jiffies;
907 break;
908 }
909
910 dprintk("nlmsvc_retry_blocked(%p, when=%ld)\n",
911 block, block->b_when);
912 if (block->b_flags & B_QUEUED) {
913 dprintk("nlmsvc_retry_blocked delete block (%p, granted=%d, flags=%d)\n",
914 block, block->b_granted, block->b_flags);
915 retry_deferred_block(block);
916 } else
917 nlmsvc_grant_blocked(block);
918 }
919
920 return timeout;
921 }