xref: /openbmc/linux/fs/lockd/svclock.c (revision d5cb9783536a41df9f9cba5b0a1d78047ed787f7)
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/config.h>
24 #include <linux/types.h>
25 #include <linux/errno.h>
26 #include <linux/kernel.h>
27 #include <linux/sched.h>
28 #include <linux/smp_lock.h>
29 #include <linux/sunrpc/clnt.h>
30 #include <linux/sunrpc/svc.h>
31 #include <linux/lockd/nlm.h>
32 #include <linux/lockd/lockd.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_insert_block(struct nlm_block *block, unsigned long);
43 static int	nlmsvc_remove_block(struct nlm_block *block);
44 static void	nlmsvc_grant_callback(struct rpc_task *task);
45 
46 /*
47  * The list of blocked locks to retry
48  */
49 static struct nlm_block *	nlm_blocked;
50 
51 /*
52  * Insert a blocked lock into the global list
53  */
54 static void
55 nlmsvc_insert_block(struct nlm_block *block, unsigned long when)
56 {
57 	struct nlm_block **bp, *b;
58 
59 	dprintk("lockd: nlmsvc_insert_block(%p, %ld)\n", block, when);
60 	if (block->b_queued)
61 		nlmsvc_remove_block(block);
62 	bp = &nlm_blocked;
63 	if (when != NLM_NEVER) {
64 		if ((when += jiffies) == NLM_NEVER)
65 			when ++;
66 		while ((b = *bp) && time_before_eq(b->b_when,when) && b->b_when != NLM_NEVER)
67 			bp = &b->b_next;
68 	} else
69 		while ((b = *bp) != 0)
70 			bp = &b->b_next;
71 
72 	block->b_queued = 1;
73 	block->b_when = when;
74 	block->b_next = b;
75 	*bp = block;
76 }
77 
78 /*
79  * Remove a block from the global list
80  */
81 static int
82 nlmsvc_remove_block(struct nlm_block *block)
83 {
84 	struct nlm_block **bp, *b;
85 
86 	if (!block->b_queued)
87 		return 1;
88 	for (bp = &nlm_blocked; (b = *bp) != 0; bp = &b->b_next) {
89 		if (b == block) {
90 			*bp = block->b_next;
91 			block->b_queued = 0;
92 			return 1;
93 		}
94 	}
95 
96 	return 0;
97 }
98 
99 /*
100  * Find a block for a given lock and optionally remove it from
101  * the list.
102  */
103 static struct nlm_block *
104 nlmsvc_lookup_block(struct nlm_file *file, struct nlm_lock *lock, int remove)
105 {
106 	struct nlm_block	**head, *block;
107 	struct file_lock	*fl;
108 
109 	dprintk("lockd: nlmsvc_lookup_block f=%p pd=%d %Ld-%Ld ty=%d\n",
110 				file, lock->fl.fl_pid,
111 				(long long)lock->fl.fl_start,
112 				(long long)lock->fl.fl_end, lock->fl.fl_type);
113 	for (head = &nlm_blocked; (block = *head) != 0; head = &block->b_next) {
114 		fl = &block->b_call.a_args.lock.fl;
115 		dprintk("lockd: check f=%p pd=%d %Ld-%Ld ty=%d cookie=%s\n",
116 				block->b_file, fl->fl_pid,
117 				(long long)fl->fl_start,
118 				(long long)fl->fl_end, fl->fl_type,
119 				nlmdbg_cookie2a(&block->b_call.a_args.cookie));
120 		if (block->b_file == file && nlm_compare_locks(fl, &lock->fl)) {
121 			if (remove) {
122 				*head = block->b_next;
123 				block->b_queued = 0;
124 			}
125 			return block;
126 		}
127 	}
128 
129 	return NULL;
130 }
131 
132 static inline int nlm_cookie_match(struct nlm_cookie *a, struct nlm_cookie *b)
133 {
134 	if(a->len != b->len)
135 		return 0;
136 	if(memcmp(a->data,b->data,a->len))
137 		return 0;
138 	return 1;
139 }
140 
141 /*
142  * Find a block with a given NLM cookie.
143  */
144 static inline struct nlm_block *
145 nlmsvc_find_block(struct nlm_cookie *cookie,  struct sockaddr_in *sin)
146 {
147 	struct nlm_block *block;
148 
149 	for (block = nlm_blocked; block; block = block->b_next) {
150 		dprintk("cookie: head of blocked queue %p, block %p\n",
151 			nlm_blocked, block);
152 		if (nlm_cookie_match(&block->b_call.a_args.cookie,cookie)
153 				&& nlm_cmp_addr(sin, &block->b_host->h_addr))
154 			break;
155 	}
156 
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 static inline struct nlm_block *
171 nlmsvc_create_block(struct svc_rqst *rqstp, struct nlm_file *file,
172 				struct nlm_lock *lock, struct nlm_cookie *cookie)
173 {
174 	struct nlm_block	*block;
175 	struct nlm_host		*host;
176 	struct nlm_rqst		*call;
177 
178 	/* Create host handle for callback */
179 	host = nlmclnt_lookup_host(&rqstp->rq_addr,
180 				rqstp->rq_prot, rqstp->rq_vers);
181 	if (host == NULL)
182 		return NULL;
183 
184 	/* Allocate memory for block, and initialize arguments */
185 	if (!(block = (struct nlm_block *) kmalloc(sizeof(*block), GFP_KERNEL)))
186 		goto failed;
187 	memset(block, 0, sizeof(*block));
188 	locks_init_lock(&block->b_call.a_args.lock.fl);
189 	locks_init_lock(&block->b_call.a_res.lock.fl);
190 
191 	if (!nlmclnt_setgrantargs(&block->b_call, lock))
192 		goto failed_free;
193 
194 	/* Set notifier function for VFS, and init args */
195 	block->b_call.a_args.lock.fl.fl_lmops = &nlmsvc_lock_operations;
196 	block->b_call.a_args.cookie = *cookie;	/* see above */
197 
198 	dprintk("lockd: created block %p...\n", block);
199 
200 	/* Create and initialize the block */
201 	block->b_daemon = rqstp->rq_server;
202 	block->b_host   = host;
203 	block->b_file   = file;
204 
205 	/* Add to file's list of blocks */
206 	block->b_fnext  = file->f_blocks;
207 	file->f_blocks  = block;
208 
209 	/* Set up RPC arguments for callback */
210 	call = &block->b_call;
211 	call->a_host    = host;
212 	call->a_flags   = RPC_TASK_ASYNC;
213 
214 	return block;
215 
216 failed_free:
217 	kfree(block);
218 failed:
219 	nlm_release_host(host);
220 	return NULL;
221 }
222 
223 /*
224  * Delete a block. If the lock was cancelled or the grant callback
225  * failed, unlock is set to 1.
226  * It is the caller's responsibility to check whether the file
227  * can be closed hereafter.
228  */
229 static void
230 nlmsvc_delete_block(struct nlm_block *block, int unlock)
231 {
232 	struct file_lock	*fl = &block->b_call.a_args.lock.fl;
233 	struct nlm_file		*file = block->b_file;
234 	struct nlm_block	**bp;
235 
236 	dprintk("lockd: deleting block %p...\n", block);
237 
238 	/* Remove block from list */
239 	nlmsvc_remove_block(block);
240 	if (fl->fl_next)
241 		posix_unblock_lock(file->f_file, fl);
242 	if (unlock) {
243 		fl->fl_type = F_UNLCK;
244 		posix_lock_file(file->f_file, fl);
245 		block->b_granted = 0;
246 	}
247 
248 	/* If the block is in the middle of a GRANT callback,
249 	 * don't kill it yet. */
250 	if (block->b_incall) {
251 		nlmsvc_insert_block(block, NLM_NEVER);
252 		block->b_done = 1;
253 		return;
254 	}
255 
256 	/* Remove block from file's list of blocks */
257 	for (bp = &file->f_blocks; *bp; bp = &(*bp)->b_fnext) {
258 		if (*bp == block) {
259 			*bp = block->b_fnext;
260 			break;
261 		}
262 	}
263 
264 	if (block->b_host)
265 		nlm_release_host(block->b_host);
266 	nlmclnt_freegrantargs(&block->b_call);
267 	kfree(block);
268 }
269 
270 /*
271  * Loop over all blocks and perform the action specified.
272  * (NLM_ACT_CHECK handled by nlmsvc_inspect_file).
273  */
274 int
275 nlmsvc_traverse_blocks(struct nlm_host *host, struct nlm_file *file, int action)
276 {
277 	struct nlm_block	*block, *next;
278 
279 	down(&file->f_sema);
280 	for (block = file->f_blocks; block; block = next) {
281 		next = block->b_fnext;
282 		if (action == NLM_ACT_MARK)
283 			block->b_host->h_inuse = 1;
284 		else if (action == NLM_ACT_UNLOCK) {
285 			if (host == NULL || host == block->b_host)
286 				nlmsvc_delete_block(block, 1);
287 		}
288 	}
289 	up(&file->f_sema);
290 	return 0;
291 }
292 
293 /*
294  * Attempt to establish a lock, and if it can't be granted, block it
295  * if required.
296  */
297 u32
298 nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file,
299 			struct nlm_lock *lock, int wait, struct nlm_cookie *cookie)
300 {
301 	struct file_lock	*conflock;
302 	struct nlm_block	*block;
303 	int			error;
304 
305 	dprintk("lockd: nlmsvc_lock(%s/%ld, ty=%d, pi=%d, %Ld-%Ld, bl=%d)\n",
306 				file->f_file->f_dentry->d_inode->i_sb->s_id,
307 				file->f_file->f_dentry->d_inode->i_ino,
308 				lock->fl.fl_type, lock->fl.fl_pid,
309 				(long long)lock->fl.fl_start,
310 				(long long)lock->fl.fl_end,
311 				wait);
312 
313 
314 	/* Get existing block (in case client is busy-waiting) */
315 	block = nlmsvc_lookup_block(file, lock, 0);
316 
317 	lock->fl.fl_flags |= FL_LOCKD;
318 
319 again:
320 	/* Lock file against concurrent access */
321 	down(&file->f_sema);
322 
323 	if (!(conflock = posix_test_lock(file->f_file, &lock->fl))) {
324 		error = posix_lock_file(file->f_file, &lock->fl);
325 
326 		if (block)
327 			nlmsvc_delete_block(block, 0);
328 		up(&file->f_sema);
329 
330 		dprintk("lockd: posix_lock_file returned %d\n", -error);
331 		switch(-error) {
332 		case 0:
333 			return nlm_granted;
334 		case EDEADLK:
335 			return nlm_deadlock;
336 		case EAGAIN:
337 			return nlm_lck_denied;
338 		default:			/* includes ENOLCK */
339 			return nlm_lck_denied_nolocks;
340 		}
341 	}
342 
343 	if (!wait) {
344 		up(&file->f_sema);
345 		return nlm_lck_denied;
346 	}
347 
348 	if (posix_locks_deadlock(&lock->fl, conflock)) {
349 		up(&file->f_sema);
350 		return nlm_deadlock;
351 	}
352 
353 	/* If we don't have a block, create and initialize it. Then
354 	 * retry because we may have slept in kmalloc. */
355 	/* We have to release f_sema as nlmsvc_create_block may try to
356 	 * to claim it while doing host garbage collection */
357 	if (block == NULL) {
358 		up(&file->f_sema);
359 		dprintk("lockd: blocking on this lock (allocating).\n");
360 		if (!(block = nlmsvc_create_block(rqstp, file, lock, cookie)))
361 			return nlm_lck_denied_nolocks;
362 		goto again;
363 	}
364 
365 	/* Append to list of blocked */
366 	nlmsvc_insert_block(block, NLM_NEVER);
367 
368 	if (list_empty(&block->b_call.a_args.lock.fl.fl_block)) {
369 		/* Now add block to block list of the conflicting lock
370 		   if we haven't done so. */
371 		dprintk("lockd: blocking on this lock.\n");
372 		posix_block_lock(conflock, &block->b_call.a_args.lock.fl);
373 	}
374 
375 	up(&file->f_sema);
376 	return nlm_lck_blocked;
377 }
378 
379 /*
380  * Test for presence of a conflicting lock.
381  */
382 u32
383 nlmsvc_testlock(struct nlm_file *file, struct nlm_lock *lock,
384 				       struct nlm_lock *conflock)
385 {
386 	struct file_lock	*fl;
387 
388 	dprintk("lockd: nlmsvc_testlock(%s/%ld, ty=%d, %Ld-%Ld)\n",
389 				file->f_file->f_dentry->d_inode->i_sb->s_id,
390 				file->f_file->f_dentry->d_inode->i_ino,
391 				lock->fl.fl_type,
392 				(long long)lock->fl.fl_start,
393 				(long long)lock->fl.fl_end);
394 
395 	if ((fl = posix_test_lock(file->f_file, &lock->fl)) != NULL) {
396 		dprintk("lockd: conflicting lock(ty=%d, %Ld-%Ld)\n",
397 				fl->fl_type, (long long)fl->fl_start,
398 				(long long)fl->fl_end);
399 		conflock->caller = "somehost";	/* FIXME */
400 		conflock->oh.len = 0;		/* don't return OH info */
401 		conflock->fl = *fl;
402 		return nlm_lck_denied;
403 	}
404 
405 	return nlm_granted;
406 }
407 
408 /*
409  * Remove a lock.
410  * This implies a CANCEL call: We send a GRANT_MSG, the client replies
411  * with a GRANT_RES call which gets lost, and calls UNLOCK immediately
412  * afterwards. In this case the block will still be there, and hence
413  * must be removed.
414  */
415 u32
416 nlmsvc_unlock(struct nlm_file *file, struct nlm_lock *lock)
417 {
418 	int	error;
419 
420 	dprintk("lockd: nlmsvc_unlock(%s/%ld, pi=%d, %Ld-%Ld)\n",
421 				file->f_file->f_dentry->d_inode->i_sb->s_id,
422 				file->f_file->f_dentry->d_inode->i_ino,
423 				lock->fl.fl_pid,
424 				(long long)lock->fl.fl_start,
425 				(long long)lock->fl.fl_end);
426 
427 	/* First, cancel any lock that might be there */
428 	nlmsvc_cancel_blocked(file, lock);
429 
430 	lock->fl.fl_type = F_UNLCK;
431 	error = posix_lock_file(file->f_file, &lock->fl);
432 
433 	return (error < 0)? nlm_lck_denied_nolocks : nlm_granted;
434 }
435 
436 /*
437  * Cancel a previously blocked request.
438  *
439  * A cancel request always overrides any grant that may currently
440  * be in progress.
441  * The calling procedure must check whether the file can be closed.
442  */
443 u32
444 nlmsvc_cancel_blocked(struct nlm_file *file, struct nlm_lock *lock)
445 {
446 	struct nlm_block	*block;
447 
448 	dprintk("lockd: nlmsvc_cancel(%s/%ld, pi=%d, %Ld-%Ld)\n",
449 				file->f_file->f_dentry->d_inode->i_sb->s_id,
450 				file->f_file->f_dentry->d_inode->i_ino,
451 				lock->fl.fl_pid,
452 				(long long)lock->fl.fl_start,
453 				(long long)lock->fl.fl_end);
454 
455 	down(&file->f_sema);
456 	if ((block = nlmsvc_lookup_block(file, lock, 1)) != NULL)
457 		nlmsvc_delete_block(block, 1);
458 	up(&file->f_sema);
459 	return nlm_granted;
460 }
461 
462 /*
463  * Unblock a blocked lock request. This is a callback invoked from the
464  * VFS layer when a lock on which we blocked is removed.
465  *
466  * This function doesn't grant the blocked lock instantly, but rather moves
467  * the block to the head of nlm_blocked where it can be picked up by lockd.
468  */
469 static void
470 nlmsvc_notify_blocked(struct file_lock *fl)
471 {
472 	struct nlm_block	**bp, *block;
473 
474 	dprintk("lockd: VFS unblock notification for block %p\n", fl);
475 	for (bp = &nlm_blocked; (block = *bp) != 0; bp = &block->b_next) {
476 		if (nlm_compare_locks(&block->b_call.a_args.lock.fl, fl)) {
477 			nlmsvc_insert_block(block, 0);
478 			svc_wake_up(block->b_daemon);
479 			return;
480 		}
481 	}
482 
483 	printk(KERN_WARNING "lockd: notification for unknown block!\n");
484 }
485 
486 static int nlmsvc_same_owner(struct file_lock *fl1, struct file_lock *fl2)
487 {
488 	return fl1->fl_owner == fl2->fl_owner && fl1->fl_pid == fl2->fl_pid;
489 }
490 
491 struct lock_manager_operations nlmsvc_lock_operations = {
492 	.fl_compare_owner = nlmsvc_same_owner,
493 	.fl_notify = nlmsvc_notify_blocked,
494 };
495 
496 /*
497  * Try to claim a lock that was previously blocked.
498  *
499  * Note that we use both the RPC_GRANTED_MSG call _and_ an async
500  * RPC thread when notifying the client. This seems like overkill...
501  * Here's why:
502  *  -	we don't want to use a synchronous RPC thread, otherwise
503  *	we might find ourselves hanging on a dead portmapper.
504  *  -	Some lockd implementations (e.g. HP) don't react to
505  *	RPC_GRANTED calls; they seem to insist on RPC_GRANTED_MSG calls.
506  */
507 static void
508 nlmsvc_grant_blocked(struct nlm_block *block)
509 {
510 	struct nlm_file		*file = block->b_file;
511 	struct nlm_lock		*lock = &block->b_call.a_args.lock;
512 	struct file_lock	*conflock;
513 	int			error;
514 
515 	dprintk("lockd: grant blocked lock %p\n", block);
516 
517 	/* First thing is lock the file */
518 	down(&file->f_sema);
519 
520 	/* Unlink block request from list */
521 	nlmsvc_remove_block(block);
522 
523 	/* If b_granted is true this means we've been here before.
524 	 * Just retry the grant callback, possibly refreshing the RPC
525 	 * binding */
526 	if (block->b_granted) {
527 		nlm_rebind_host(block->b_host);
528 		goto callback;
529 	}
530 
531 	/* Try the lock operation again */
532 	if ((conflock = posix_test_lock(file->f_file, &lock->fl)) != NULL) {
533 		/* Bummer, we blocked again */
534 		dprintk("lockd: lock still blocked\n");
535 		nlmsvc_insert_block(block, NLM_NEVER);
536 		posix_block_lock(conflock, &lock->fl);
537 		up(&file->f_sema);
538 		return;
539 	}
540 
541 	/* Alright, no conflicting lock. Now lock it for real. If the
542 	 * following yields an error, this is most probably due to low
543 	 * memory. Retry the lock in a few seconds.
544 	 */
545 	if ((error = posix_lock_file(file->f_file, &lock->fl)) < 0) {
546 		printk(KERN_WARNING "lockd: unexpected error %d in %s!\n",
547 				-error, __FUNCTION__);
548 		nlmsvc_insert_block(block, 10 * HZ);
549 		up(&file->f_sema);
550 		return;
551 	}
552 
553 callback:
554 	/* Lock was granted by VFS. */
555 	dprintk("lockd: GRANTing blocked lock.\n");
556 	block->b_granted = 1;
557 	block->b_incall  = 1;
558 
559 	/* Schedule next grant callback in 30 seconds */
560 	nlmsvc_insert_block(block, 30 * HZ);
561 
562 	/* Call the client */
563 	nlm_get_host(block->b_call.a_host);
564 	if (nlmsvc_async_call(&block->b_call, NLMPROC_GRANTED_MSG,
565 						nlmsvc_grant_callback) < 0)
566 		nlm_release_host(block->b_call.a_host);
567 	up(&file->f_sema);
568 }
569 
570 /*
571  * This is the callback from the RPC layer when the NLM_GRANTED_MSG
572  * RPC call has succeeded or timed out.
573  * Like all RPC callbacks, it is invoked by the rpciod process, so it
574  * better not sleep. Therefore, we put the blocked lock on the nlm_blocked
575  * chain once more in order to have it removed by lockd itself (which can
576  * then sleep on the file semaphore without disrupting e.g. the nfs client).
577  */
578 static void
579 nlmsvc_grant_callback(struct rpc_task *task)
580 {
581 	struct nlm_rqst		*call = (struct nlm_rqst *) task->tk_calldata;
582 	struct nlm_block	*block;
583 	unsigned long		timeout;
584 	struct sockaddr_in	*peer_addr = RPC_PEERADDR(task->tk_client);
585 
586 	dprintk("lockd: GRANT_MSG RPC callback\n");
587 	dprintk("callback: looking for cookie %s, host (%u.%u.%u.%u)\n",
588 		nlmdbg_cookie2a(&call->a_args.cookie),
589 		NIPQUAD(peer_addr->sin_addr.s_addr));
590 	if (!(block = nlmsvc_find_block(&call->a_args.cookie, peer_addr))) {
591 		dprintk("lockd: no block for cookie %s, host (%u.%u.%u.%u)\n",
592 			nlmdbg_cookie2a(&call->a_args.cookie),
593 			NIPQUAD(peer_addr->sin_addr.s_addr));
594 		return;
595 	}
596 
597 	/* Technically, we should down the file semaphore here. Since we
598 	 * move the block towards the head of the queue only, no harm
599 	 * can be done, though. */
600 	if (task->tk_status < 0) {
601 		/* RPC error: Re-insert for retransmission */
602 		timeout = 10 * HZ;
603 	} else if (block->b_done) {
604 		/* Block already removed, kill it for real */
605 		timeout = 0;
606 	} else {
607 		/* Call was successful, now wait for client callback */
608 		timeout = 60 * HZ;
609 	}
610 	nlmsvc_insert_block(block, timeout);
611 	svc_wake_up(block->b_daemon);
612 	block->b_incall = 0;
613 
614 	nlm_release_host(call->a_host);
615 }
616 
617 /*
618  * We received a GRANT_RES callback. Try to find the corresponding
619  * block.
620  */
621 void
622 nlmsvc_grant_reply(struct svc_rqst *rqstp, struct nlm_cookie *cookie, u32 status)
623 {
624 	struct nlm_block	*block;
625 	struct nlm_file		*file;
626 
627 	dprintk("grant_reply: looking for cookie %x, host (%08x), s=%d \n",
628 		*(unsigned int *)(cookie->data),
629 		ntohl(rqstp->rq_addr.sin_addr.s_addr), status);
630 	if (!(block = nlmsvc_find_block(cookie, &rqstp->rq_addr)))
631 		return;
632 	file = block->b_file;
633 
634 	file->f_count++;
635 	down(&file->f_sema);
636 	if ((block = nlmsvc_find_block(cookie,&rqstp->rq_addr)) != NULL) {
637 		if (status == NLM_LCK_DENIED_GRACE_PERIOD) {
638 			/* Try again in a couple of seconds */
639 			nlmsvc_insert_block(block, 10 * HZ);
640 			block = NULL;
641 		} else {
642 			/* Lock is now held by client, or has been rejected.
643 			 * In both cases, the block should be removed. */
644 			up(&file->f_sema);
645 			if (status == NLM_LCK_GRANTED)
646 				nlmsvc_delete_block(block, 0);
647 			else
648 				nlmsvc_delete_block(block, 1);
649 		}
650 	}
651 	if (!block)
652 		up(&file->f_sema);
653 	nlm_release_file(file);
654 }
655 
656 /*
657  * Retry all blocked locks that have been notified. This is where lockd
658  * picks up locks that can be granted, or grant notifications that must
659  * be retransmitted.
660  */
661 unsigned long
662 nlmsvc_retry_blocked(void)
663 {
664 	struct nlm_block	*block;
665 
666 	dprintk("nlmsvc_retry_blocked(%p, when=%ld)\n",
667 			nlm_blocked,
668 			nlm_blocked? nlm_blocked->b_when : 0);
669 	while ((block = nlm_blocked) != 0) {
670 		if (block->b_when == NLM_NEVER)
671 			break;
672 	        if (time_after(block->b_when,jiffies))
673 			break;
674 		dprintk("nlmsvc_retry_blocked(%p, when=%ld, done=%d)\n",
675 			block, block->b_when, block->b_done);
676 		if (block->b_done)
677 			nlmsvc_delete_block(block, 0);
678 		else
679 			nlmsvc_grant_blocked(block);
680 	}
681 
682 	if ((block = nlm_blocked) && block->b_when != NLM_NEVER)
683 		return (block->b_when - jiffies);
684 
685 	return MAX_SCHEDULE_TIMEOUT;
686 }
687