Merge master.kernel.org:/pub/scm/linux/kernel/git/davej/agpgart
[linux-2.6.git] / fs / lockd / svclock.c
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
45 static const struct rpc_call_ops nlmsvc_grant_ops;
46
47 /*
48  * The list of blocked locks to retry
49  */
50 static struct nlm_block *       nlm_blocked;
51
52 /*
53  * Insert a blocked lock into the global list
54  */
55 static void
56 nlmsvc_insert_block(struct nlm_block *block, unsigned long when)
57 {
58         struct nlm_block **bp, *b;
59
60         dprintk("lockd: nlmsvc_insert_block(%p, %ld)\n", block, when);
61         if (block->b_queued)
62                 nlmsvc_remove_block(block);
63         bp = &nlm_blocked;
64         if (when != NLM_NEVER) {
65                 if ((when += jiffies) == NLM_NEVER)
66                         when ++;
67                 while ((b = *bp) && time_before_eq(b->b_when,when) && b->b_when != NLM_NEVER)
68                         bp = &b->b_next;
69         } else
70                 while ((b = *bp) != 0)
71                         bp = &b->b_next;
72
73         block->b_queued = 1;
74         block->b_when = when;
75         block->b_next = b;
76         *bp = block;
77 }
78
79 /*
80  * Remove a block from the global list
81  */
82 static int
83 nlmsvc_remove_block(struct nlm_block *block)
84 {
85         struct nlm_block **bp, *b;
86
87         if (!block->b_queued)
88                 return 1;
89         for (bp = &nlm_blocked; (b = *bp) != 0; bp = &b->b_next) {
90                 if (b == block) {
91                         *bp = block->b_next;
92                         block->b_queued = 0;
93                         return 1;
94                 }
95         }
96
97         return 0;
98 }
99
100 /*
101  * Find a block for a given lock and optionally remove it from
102  * the list.
103  */
104 static struct nlm_block *
105 nlmsvc_lookup_block(struct nlm_file *file, struct nlm_lock *lock, int remove)
106 {
107         struct nlm_block        **head, *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         for (head = &nlm_blocked; (block = *head) != 0; head = &block->b_next) {
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                         if (remove) {
123                                 *head = block->b_next;
124                                 block->b_queued = 0;
125                         }
126                         return block;
127                 }
128         }
129
130         return NULL;
131 }
132
133 static inline int nlm_cookie_match(struct nlm_cookie *a, struct nlm_cookie *b)
134 {
135         if(a->len != b->len)
136                 return 0;
137         if(memcmp(a->data,b->data,a->len))
138                 return 0;
139         return 1;
140 }
141
142 /*
143  * Find a block with a given NLM cookie.
144  */
145 static inline struct nlm_block *
146 nlmsvc_find_block(struct nlm_cookie *cookie,  struct sockaddr_in *sin)
147 {
148         struct nlm_block *block;
149
150         for (block = nlm_blocked; block; block = block->b_next) {
151                 dprintk("cookie: head of blocked queue %p, block %p\n", 
152                         nlm_blocked, block);
153                 if (nlm_cookie_match(&block->b_call.a_args.cookie,cookie)
154                                 && nlm_cmp_addr(sin, &block->b_host->h_addr))
155                         break;
156         }
157
158         return block;
159 }
160
161 /*
162  * Create a block and initialize it.
163  *
164  * Note: we explicitly set the cookie of the grant reply to that of
165  * the blocked lock request. The spec explicitly mentions that the client
166  * should _not_ rely on the callback containing the same cookie as the
167  * request, but (as I found out later) that's because some implementations
168  * do just this. Never mind the standards comittees, they support our
169  * logging industries.
170  */
171 static inline struct nlm_block *
172 nlmsvc_create_block(struct svc_rqst *rqstp, struct nlm_file *file,
173                                 struct nlm_lock *lock, struct nlm_cookie *cookie)
174 {
175         struct nlm_block        *block;
176         struct nlm_host         *host;
177         struct nlm_rqst         *call;
178
179         /* Create host handle for callback */
180         host = nlmclnt_lookup_host(&rqstp->rq_addr,
181                                 rqstp->rq_prot, rqstp->rq_vers);
182         if (host == NULL)
183                 return NULL;
184
185         /* Allocate memory for block, and initialize arguments */
186         if (!(block = (struct nlm_block *) kmalloc(sizeof(*block), GFP_KERNEL)))
187                 goto failed;
188         memset(block, 0, sizeof(*block));
189         locks_init_lock(&block->b_call.a_args.lock.fl);
190         locks_init_lock(&block->b_call.a_res.lock.fl);
191
192         if (!nlmclnt_setgrantargs(&block->b_call, lock))
193                 goto failed_free;
194
195         /* Set notifier function for VFS, and init args */
196         block->b_call.a_args.lock.fl.fl_lmops = &nlmsvc_lock_operations;
197         block->b_call.a_args.cookie = *cookie;  /* see above */
198
199         dprintk("lockd: created block %p...\n", block);
200
201         /* Create and initialize the block */
202         block->b_daemon = rqstp->rq_server;
203         block->b_host   = host;
204         block->b_file   = file;
205
206         /* Add to file's list of blocks */
207         block->b_fnext  = file->f_blocks;
208         file->f_blocks  = block;
209
210         /* Set up RPC arguments for callback */
211         call = &block->b_call;
212         call->a_host    = host;
213         call->a_flags   = RPC_TASK_ASYNC;
214
215         return block;
216
217 failed_free:
218         kfree(block);
219 failed:
220         nlm_release_host(host);
221         return NULL;
222 }
223
224 /*
225  * Delete a block. If the lock was cancelled or the grant callback
226  * failed, unlock is set to 1.
227  * It is the caller's responsibility to check whether the file
228  * can be closed hereafter.
229  */
230 static int
231 nlmsvc_delete_block(struct nlm_block *block, int unlock)
232 {
233         struct file_lock        *fl = &block->b_call.a_args.lock.fl;
234         struct nlm_file         *file = block->b_file;
235         struct nlm_block        **bp;
236         int status = 0;
237
238         dprintk("lockd: deleting block %p...\n", block);
239
240         /* Remove block from list */
241         nlmsvc_remove_block(block);
242         if (unlock)
243                 status = posix_unblock_lock(file->f_file, fl);
244
245         /* If the block is in the middle of a GRANT callback,
246          * don't kill it yet. */
247         if (block->b_incall) {
248                 nlmsvc_insert_block(block, NLM_NEVER);
249                 block->b_done = 1;
250                 return status;
251         }
252
253         /* Remove block from file's list of blocks */
254         for (bp = &file->f_blocks; *bp; bp = &(*bp)->b_fnext) {
255                 if (*bp == block) {
256                         *bp = block->b_fnext;
257                         break;
258                 }
259         }
260
261         if (block->b_host)
262                 nlm_release_host(block->b_host);
263         nlmclnt_freegrantargs(&block->b_call);
264         kfree(block);
265         return status;
266 }
267
268 /*
269  * Loop over all blocks and perform the action specified.
270  * (NLM_ACT_CHECK handled by nlmsvc_inspect_file).
271  */
272 int
273 nlmsvc_traverse_blocks(struct nlm_host *host, struct nlm_file *file, int action)
274 {
275         struct nlm_block        *block, *next;
276         /* XXX: Will everything get cleaned up if we don't unlock here? */
277
278         down(&file->f_sema);
279         for (block = file->f_blocks; block; block = next) {
280                 next = block->b_fnext;
281                 if (action == NLM_ACT_MARK)
282                         block->b_host->h_inuse = 1;
283                 else if (action == NLM_ACT_UNLOCK) {
284                         if (host == NULL || host == block->b_host)
285                                 nlmsvc_delete_block(block, 1);
286                 }
287         }
288         up(&file->f_sema);
289         return 0;
290 }
291
292 /*
293  * Attempt to establish a lock, and if it can't be granted, block it
294  * if required.
295  */
296 u32
297 nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file,
298                         struct nlm_lock *lock, int wait, struct nlm_cookie *cookie)
299 {
300         struct file_lock        *conflock;
301         struct nlm_block        *block;
302         int                     error;
303
304         dprintk("lockd: nlmsvc_lock(%s/%ld, ty=%d, pi=%d, %Ld-%Ld, bl=%d)\n",
305                                 file->f_file->f_dentry->d_inode->i_sb->s_id,
306                                 file->f_file->f_dentry->d_inode->i_ino,
307                                 lock->fl.fl_type, lock->fl.fl_pid,
308                                 (long long)lock->fl.fl_start,
309                                 (long long)lock->fl.fl_end,
310                                 wait);
311
312
313         /* Get existing block (in case client is busy-waiting) */
314         block = nlmsvc_lookup_block(file, lock, 0);
315
316         lock->fl.fl_flags |= FL_LOCKD;
317
318 again:
319         /* Lock file against concurrent access */
320         down(&file->f_sema);
321
322         if (!(conflock = posix_test_lock(file->f_file, &lock->fl))) {
323                 error = posix_lock_file(file->f_file, &lock->fl);
324
325                 if (block)
326                         nlmsvc_delete_block(block, 0);
327                 up(&file->f_sema);
328
329                 dprintk("lockd: posix_lock_file returned %d\n", -error);
330                 switch(-error) {
331                 case 0:
332                         return nlm_granted;
333                 case EDEADLK:
334                         return nlm_deadlock;
335                 case EAGAIN:
336                         return nlm_lck_denied;
337                 default:                        /* includes ENOLCK */
338                         return nlm_lck_denied_nolocks;
339                 }
340         }
341
342         if (!wait) {
343                 up(&file->f_sema);
344                 return nlm_lck_denied;
345         }
346
347         if (posix_locks_deadlock(&lock->fl, conflock)) {
348                 up(&file->f_sema);
349                 return nlm_deadlock;
350         }
351
352         /* If we don't have a block, create and initialize it. Then
353          * retry because we may have slept in kmalloc. */
354         /* We have to release f_sema as nlmsvc_create_block may try to
355          * to claim it while doing host garbage collection */
356         if (block == NULL) {
357                 up(&file->f_sema);
358                 dprintk("lockd: blocking on this lock (allocating).\n");
359                 if (!(block = nlmsvc_create_block(rqstp, file, lock, cookie)))
360                         return nlm_lck_denied_nolocks;
361                 goto again;
362         }
363
364         /* Append to list of blocked */
365         nlmsvc_insert_block(block, NLM_NEVER);
366
367         if (list_empty(&block->b_call.a_args.lock.fl.fl_block)) {
368                 /* Now add block to block list of the conflicting lock
369                    if we haven't done so. */
370                 dprintk("lockd: blocking on this lock.\n");
371                 posix_block_lock(conflock, &block->b_call.a_args.lock.fl);
372         }
373
374         up(&file->f_sema);
375         return nlm_lck_blocked;
376 }
377
378 /*
379  * Test for presence of a conflicting lock.
380  */
381 u32
382 nlmsvc_testlock(struct nlm_file *file, struct nlm_lock *lock,
383                                        struct nlm_lock *conflock)
384 {
385         struct file_lock        *fl;
386
387         dprintk("lockd: nlmsvc_testlock(%s/%ld, ty=%d, %Ld-%Ld)\n",
388                                 file->f_file->f_dentry->d_inode->i_sb->s_id,
389                                 file->f_file->f_dentry->d_inode->i_ino,
390                                 lock->fl.fl_type,
391                                 (long long)lock->fl.fl_start,
392                                 (long long)lock->fl.fl_end);
393
394         if ((fl = posix_test_lock(file->f_file, &lock->fl)) != NULL) {
395                 dprintk("lockd: conflicting lock(ty=%d, %Ld-%Ld)\n",
396                                 fl->fl_type, (long long)fl->fl_start,
397                                 (long long)fl->fl_end);
398                 conflock->caller = "somehost";  /* FIXME */
399                 conflock->oh.len = 0;           /* don't return OH info */
400                 conflock->fl = *fl;
401                 return nlm_lck_denied;
402         }
403
404         return nlm_granted;
405 }
406
407 /*
408  * Remove a lock.
409  * This implies a CANCEL call: We send a GRANT_MSG, the client replies
410  * with a GRANT_RES call which gets lost, and calls UNLOCK immediately
411  * afterwards. In this case the block will still be there, and hence
412  * must be removed.
413  */
414 u32
415 nlmsvc_unlock(struct nlm_file *file, struct nlm_lock *lock)
416 {
417         int     error;
418
419         dprintk("lockd: nlmsvc_unlock(%s/%ld, pi=%d, %Ld-%Ld)\n",
420                                 file->f_file->f_dentry->d_inode->i_sb->s_id,
421                                 file->f_file->f_dentry->d_inode->i_ino,
422                                 lock->fl.fl_pid,
423                                 (long long)lock->fl.fl_start,
424                                 (long long)lock->fl.fl_end);
425
426         /* First, cancel any lock that might be there */
427         nlmsvc_cancel_blocked(file, lock);
428
429         lock->fl.fl_type = F_UNLCK;
430         error = posix_lock_file(file->f_file, &lock->fl);
431
432         return (error < 0)? nlm_lck_denied_nolocks : nlm_granted;
433 }
434
435 /*
436  * Cancel a previously blocked request.
437  *
438  * A cancel request always overrides any grant that may currently
439  * be in progress.
440  * The calling procedure must check whether the file can be closed.
441  */
442 u32
443 nlmsvc_cancel_blocked(struct nlm_file *file, struct nlm_lock *lock)
444 {
445         struct nlm_block        *block;
446         int status = 0;
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                 status = nlmsvc_delete_block(block, 1);
458         up(&file->f_sema);
459         return status ? nlm_lck_denied : 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_ops) < 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 nlmsvc_grant_callback(struct rpc_task *task, void *data)
579 {
580         struct nlm_rqst         *call = data;
581         struct nlm_block        *block;
582         unsigned long           timeout;
583         struct sockaddr_in      *peer_addr = RPC_PEERADDR(task->tk_client);
584
585         dprintk("lockd: GRANT_MSG RPC callback\n");
586         dprintk("callback: looking for cookie %s, host (%u.%u.%u.%u)\n",
587                 nlmdbg_cookie2a(&call->a_args.cookie),
588                 NIPQUAD(peer_addr->sin_addr.s_addr));
589         if (!(block = nlmsvc_find_block(&call->a_args.cookie, peer_addr))) {
590                 dprintk("lockd: no block for cookie %s, host (%u.%u.%u.%u)\n",
591                         nlmdbg_cookie2a(&call->a_args.cookie),
592                         NIPQUAD(peer_addr->sin_addr.s_addr));
593                 return;
594         }
595
596         /* Technically, we should down the file semaphore here. Since we
597          * move the block towards the head of the queue only, no harm
598          * can be done, though. */
599         if (task->tk_status < 0) {
600                 /* RPC error: Re-insert for retransmission */
601                 timeout = 10 * HZ;
602         } else if (block->b_done) {
603                 /* Block already removed, kill it for real */
604                 timeout = 0;
605         } else {
606                 /* Call was successful, now wait for client callback */
607                 timeout = 60 * HZ;
608         }
609         nlmsvc_insert_block(block, timeout);
610         svc_wake_up(block->b_daemon);
611         block->b_incall = 0;
612
613         nlm_release_host(call->a_host);
614 }
615
616 static const struct rpc_call_ops nlmsvc_grant_ops = {
617         .rpc_call_done = nlmsvc_grant_callback,
618 };
619
620 /*
621  * We received a GRANT_RES callback. Try to find the corresponding
622  * block.
623  */
624 void
625 nlmsvc_grant_reply(struct svc_rqst *rqstp, struct nlm_cookie *cookie, u32 status)
626 {
627         struct nlm_block        *block;
628         struct nlm_file         *file;
629
630         dprintk("grant_reply: looking for cookie %x, host (%08x), s=%d \n", 
631                 *(unsigned int *)(cookie->data), 
632                 ntohl(rqstp->rq_addr.sin_addr.s_addr), status);
633         if (!(block = nlmsvc_find_block(cookie, &rqstp->rq_addr)))
634                 return;
635         file = block->b_file;
636
637         file->f_count++;
638         down(&file->f_sema);
639         block = nlmsvc_find_block(cookie, &rqstp->rq_addr);
640         if (block) {
641                 if (status == NLM_LCK_DENIED_GRACE_PERIOD) {
642                         /* Try again in a couple of seconds */
643                         nlmsvc_insert_block(block, 10 * HZ);
644                         up(&file->f_sema);
645                 } else {
646                         /* Lock is now held by client, or has been rejected.
647                          * In both cases, the block should be removed. */
648                         up(&file->f_sema);
649                         if (status == NLM_LCK_GRANTED)
650                                 nlmsvc_delete_block(block, 0);
651                         else
652                                 nlmsvc_delete_block(block, 1);
653                 }
654         }
655         nlm_release_file(file);
656 }
657
658 /*
659  * Retry all blocked locks that have been notified. This is where lockd
660  * picks up locks that can be granted, or grant notifications that must
661  * be retransmitted.
662  */
663 unsigned long
664 nlmsvc_retry_blocked(void)
665 {
666         struct nlm_block        *block;
667
668         dprintk("nlmsvc_retry_blocked(%p, when=%ld)\n",
669                         nlm_blocked,
670                         nlm_blocked? nlm_blocked->b_when : 0);
671         while ((block = nlm_blocked) != 0) {
672                 if (block->b_when == NLM_NEVER)
673                         break;
674                 if (time_after(block->b_when,jiffies))
675                         break;
676                 dprintk("nlmsvc_retry_blocked(%p, when=%ld, done=%d)\n",
677                         block, block->b_when, block->b_done);
678                 if (block->b_done)
679                         nlmsvc_delete_block(block, 0);
680                 else
681                         nlmsvc_grant_blocked(block);
682         }
683
684         if ((block = nlm_blocked) && block->b_when != NLM_NEVER)
685                 return (block->b_when - jiffies);
686
687         return MAX_SCHEDULE_TIMEOUT;
688 }