49f959796b665ca145b1ff9eafccd2bdf27d84a5
[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 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 }