NLM: Add nlmclnt_release_call
[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_release_block(struct nlm_block *block);
43 static void     nlmsvc_insert_block(struct nlm_block *block, unsigned long);
44 static int      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 struct nlm_block *       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 **bp, *b;
62
63         dprintk("lockd: nlmsvc_insert_block(%p, %ld)\n", block, when);
64         kref_get(&block->b_count);
65         if (block->b_queued)
66                 nlmsvc_remove_block(block);
67         bp = &nlm_blocked;
68         if (when != NLM_NEVER) {
69                 if ((when += jiffies) == NLM_NEVER)
70                         when ++;
71                 while ((b = *bp) && time_before_eq(b->b_when,when) && b->b_when != NLM_NEVER)
72                         bp = &b->b_next;
73         } else
74                 while ((b = *bp) != 0)
75                         bp = &b->b_next;
76
77         block->b_queued = 1;
78         block->b_when = when;
79         block->b_next = b;
80         *bp = block;
81 }
82
83 /*
84  * Remove a block from the global list
85  */
86 static int
87 nlmsvc_remove_block(struct nlm_block *block)
88 {
89         struct nlm_block **bp, *b;
90
91         if (!block->b_queued)
92                 return 1;
93         for (bp = &nlm_blocked; (b = *bp) != 0; bp = &b->b_next) {
94                 if (b == block) {
95                         *bp = block->b_next;
96                         block->b_queued = 0;
97                         nlmsvc_release_block(block);
98                         return 1;
99                 }
100         }
101
102         return 0;
103 }
104
105 /*
106  * Find a block for a given lock and optionally remove it from
107  * the list.
108  */
109 static struct nlm_block *
110 nlmsvc_lookup_block(struct nlm_file *file, struct nlm_lock *lock, int remove)
111 {
112         struct nlm_block        **head, *block;
113         struct file_lock        *fl;
114
115         dprintk("lockd: nlmsvc_lookup_block f=%p pd=%d %Ld-%Ld ty=%d\n",
116                                 file, lock->fl.fl_pid,
117                                 (long long)lock->fl.fl_start,
118                                 (long long)lock->fl.fl_end, lock->fl.fl_type);
119         for (head = &nlm_blocked; (block = *head) != 0; head = &block->b_next) {
120                 fl = &block->b_call->a_args.lock.fl;
121                 dprintk("lockd: check f=%p pd=%d %Ld-%Ld ty=%d cookie=%s\n",
122                                 block->b_file, fl->fl_pid,
123                                 (long long)fl->fl_start,
124                                 (long long)fl->fl_end, fl->fl_type,
125                                 nlmdbg_cookie2a(&block->b_call->a_args.cookie));
126                 if (block->b_file == file && nlm_compare_locks(fl, &lock->fl)) {
127                         if (remove) {
128                                 *head = block->b_next;
129                                 block->b_queued = 0;
130                         }
131                         kref_get(&block->b_count);
132                         return block;
133                 }
134         }
135
136         return NULL;
137 }
138
139 static inline int nlm_cookie_match(struct nlm_cookie *a, struct nlm_cookie *b)
140 {
141         if(a->len != b->len)
142                 return 0;
143         if(memcmp(a->data,b->data,a->len))
144                 return 0;
145         return 1;
146 }
147
148 /*
149  * Find a block with a given NLM cookie.
150  */
151 static inline struct nlm_block *
152 nlmsvc_find_block(struct nlm_cookie *cookie,  struct sockaddr_in *sin)
153 {
154         struct nlm_block *block;
155
156         for (block = nlm_blocked; block; block = block->b_next) {
157                 dprintk("cookie: head of blocked queue %p, block %p\n", 
158                         nlm_blocked, block);
159                 if (nlm_cookie_match(&block->b_call->a_args.cookie,cookie)
160                                 && nlm_cmp_addr(sin, &block->b_host->h_addr))
161                         break;
162         }
163
164         if (block != NULL)
165                 kref_get(&block->b_count);
166         return block;
167 }
168
169 /*
170  * Create a block and initialize it.
171  *
172  * Note: we explicitly set the cookie of the grant reply to that of
173  * the blocked lock request. The spec explicitly mentions that the client
174  * should _not_ rely on the callback containing the same cookie as the
175  * request, but (as I found out later) that's because some implementations
176  * do just this. Never mind the standards comittees, they support our
177  * logging industries.
178  */
179 static inline struct nlm_block *
180 nlmsvc_create_block(struct svc_rqst *rqstp, struct nlm_file *file,
181                                 struct nlm_lock *lock, struct nlm_cookie *cookie)
182 {
183         struct nlm_block        *block;
184         struct nlm_host         *host;
185         struct nlm_rqst         *call = NULL;
186
187         /* Create host handle for callback */
188         host = nlmsvc_lookup_host(rqstp);
189         if (host == NULL)
190                 return NULL;
191
192         call = nlm_alloc_call(host);
193         if (call == NULL)
194                 return NULL;
195
196         /* Allocate memory for block, and initialize arguments */
197         block = kzalloc(sizeof(*block), GFP_KERNEL);
198         if (block == NULL)
199                 goto failed;
200         kref_init(&block->b_count);
201
202         if (!nlmsvc_setgrantargs(call, lock))
203                 goto failed_free;
204
205         /* Set notifier function for VFS, and init args */
206         call->a_args.lock.fl.fl_flags |= FL_SLEEP;
207         call->a_args.lock.fl.fl_lmops = &nlmsvc_lock_operations;
208         call->a_args.cookie = *cookie;  /* see above */
209
210         dprintk("lockd: created block %p...\n", block);
211
212         /* Create and initialize the block */
213         block->b_daemon = rqstp->rq_server;
214         block->b_host   = host;
215         block->b_file   = file;
216
217         /* Add to file's list of blocks */
218         block->b_fnext  = file->f_blocks;
219         file->f_blocks  = block;
220
221         /* Set up RPC arguments for callback */
222         block->b_call = call;
223         call->a_flags   = RPC_TASK_ASYNC;
224         call->a_block = block;
225
226         return block;
227
228 failed_free:
229         kfree(block);
230 failed:
231         nlm_release_call(call);
232         return NULL;
233 }
234
235 /*
236  * Delete a block. If the lock was cancelled or the grant callback
237  * failed, unlock is set to 1.
238  * It is the caller's responsibility to check whether the file
239  * can be closed hereafter.
240  */
241 static int nlmsvc_unlink_block(struct nlm_block *block)
242 {
243         int status;
244         dprintk("lockd: unlinking block %p...\n", block);
245
246         /* Remove block from list */
247         status = posix_unblock_lock(block->b_file->f_file, &block->b_call->a_args.lock.fl);
248         nlmsvc_remove_block(block);
249         return status;
250 }
251
252 static void nlmsvc_free_block(struct kref *kref)
253 {
254         struct nlm_block *block = container_of(kref, struct nlm_block, b_count);
255         struct nlm_file         *file = block->b_file;
256         struct nlm_block        **bp;
257
258         dprintk("lockd: freeing block %p...\n", block);
259
260         /* Remove block from file's list of blocks */
261         for (bp = &file->f_blocks; *bp; bp = &(*bp)->b_fnext) {
262                 if (*bp == block) {
263                         *bp = block->b_fnext;
264                         break;
265                 }
266         }
267
268         nlmsvc_freegrantargs(block->b_call);
269         nlm_release_call(block->b_call);
270         kfree(block);
271 }
272
273 static void nlmsvc_release_block(struct nlm_block *block)
274 {
275         if (block != NULL)
276                 kref_put(&block->b_count, nlmsvc_free_block);
277 }
278
279 /*
280  * Loop over all blocks and perform the action specified.
281  * (NLM_ACT_CHECK handled by nlmsvc_inspect_file).
282  */
283 int
284 nlmsvc_traverse_blocks(struct nlm_host *host, struct nlm_file *file, int action)
285 {
286         struct nlm_block        *block, *next;
287         /* XXX: Will everything get cleaned up if we don't unlock here? */
288
289         down(&file->f_sema);
290         for (block = file->f_blocks; block; block = next) {
291                 next = block->b_fnext;
292                 if (action == NLM_ACT_MARK)
293                         block->b_host->h_inuse = 1;
294                 else if (action == NLM_ACT_UNLOCK) {
295                         if (host == NULL || host == block->b_host)
296                                 nlmsvc_unlink_block(block);
297                 }
298         }
299         up(&file->f_sema);
300         return 0;
301 }
302
303 /*
304  * Initialize arguments for GRANTED call. The nlm_rqst structure
305  * has been cleared already.
306  */
307 static int nlmsvc_setgrantargs(struct nlm_rqst *call, struct nlm_lock *lock)
308 {
309         locks_copy_lock(&call->a_args.lock.fl, &lock->fl);
310         memcpy(&call->a_args.lock.fh, &lock->fh, sizeof(call->a_args.lock.fh));
311         call->a_args.lock.caller = system_utsname.nodename;
312         call->a_args.lock.oh.len = lock->oh.len;
313
314         /* set default data area */
315         call->a_args.lock.oh.data = call->a_owner;
316         call->a_args.lock.svid = lock->fl.fl_pid;
317
318         if (lock->oh.len > NLMCLNT_OHSIZE) {
319                 void *data = kmalloc(lock->oh.len, GFP_KERNEL);
320                 if (!data)
321                         return 0;
322                 call->a_args.lock.oh.data = (u8 *) data;
323         }
324
325         memcpy(call->a_args.lock.oh.data, lock->oh.data, lock->oh.len);
326         return 1;
327 }
328
329 static void nlmsvc_freegrantargs(struct nlm_rqst *call)
330 {
331         if (call->a_args.lock.oh.data != call->a_owner)
332                 kfree(call->a_args.lock.oh.data);
333 }
334
335 /*
336  * Attempt to establish a lock, and if it can't be granted, block it
337  * if required.
338  */
339 u32
340 nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file,
341                         struct nlm_lock *lock, int wait, struct nlm_cookie *cookie)
342 {
343         struct nlm_block        *block, *newblock = NULL;
344         int                     error;
345         u32                     ret;
346
347         dprintk("lockd: nlmsvc_lock(%s/%ld, ty=%d, pi=%d, %Ld-%Ld, bl=%d)\n",
348                                 file->f_file->f_dentry->d_inode->i_sb->s_id,
349                                 file->f_file->f_dentry->d_inode->i_ino,
350                                 lock->fl.fl_type, lock->fl.fl_pid,
351                                 (long long)lock->fl.fl_start,
352                                 (long long)lock->fl.fl_end,
353                                 wait);
354
355
356         lock->fl.fl_flags &= ~FL_SLEEP;
357 again:
358         /* Lock file against concurrent access */
359         down(&file->f_sema);
360         /* Get existing block (in case client is busy-waiting) */
361         block = nlmsvc_lookup_block(file, lock, 0);
362         if (block == NULL) {
363                 if (newblock != NULL)
364                         lock = &newblock->b_call->a_args.lock;
365         } else
366                 lock = &block->b_call->a_args.lock;
367
368         error = posix_lock_file(file->f_file, &lock->fl);
369         lock->fl.fl_flags &= ~FL_SLEEP;
370
371         dprintk("lockd: posix_lock_file returned %d\n", error);
372
373         switch(error) {
374                 case 0:
375                         ret = nlm_granted;
376                         goto out;
377                 case -EAGAIN:
378                         break;
379                 case -EDEADLK:
380                         ret = nlm_deadlock;
381                         goto out;
382                 default:                        /* includes ENOLCK */
383                         ret = nlm_lck_denied_nolocks;
384                         goto out;
385         }
386
387         ret = nlm_lck_denied;
388         if (!wait)
389                 goto out;
390
391         ret = nlm_lck_blocked;
392         if (block != NULL)
393                 goto out;
394
395         /* If we don't have a block, create and initialize it. Then
396          * retry because we may have slept in kmalloc. */
397         /* We have to release f_sema as nlmsvc_create_block may try to
398          * to claim it while doing host garbage collection */
399         if (newblock == NULL) {
400                 up(&file->f_sema);
401                 dprintk("lockd: blocking on this lock (allocating).\n");
402                 if (!(newblock = nlmsvc_create_block(rqstp, file, lock, cookie)))
403                         return nlm_lck_denied_nolocks;
404                 goto again;
405         }
406
407         /* Append to list of blocked */
408         nlmsvc_insert_block(newblock, NLM_NEVER);
409 out:
410         up(&file->f_sema);
411         nlmsvc_release_block(newblock);
412         nlmsvc_release_block(block);
413         dprintk("lockd: nlmsvc_lock returned %u\n", ret);
414         return ret;
415 }
416
417 /*
418  * Test for presence of a conflicting lock.
419  */
420 u32
421 nlmsvc_testlock(struct nlm_file *file, struct nlm_lock *lock,
422                                        struct nlm_lock *conflock)
423 {
424         dprintk("lockd: nlmsvc_testlock(%s/%ld, ty=%d, %Ld-%Ld)\n",
425                                 file->f_file->f_dentry->d_inode->i_sb->s_id,
426                                 file->f_file->f_dentry->d_inode->i_ino,
427                                 lock->fl.fl_type,
428                                 (long long)lock->fl.fl_start,
429                                 (long long)lock->fl.fl_end);
430
431         if (posix_test_lock(file->f_file, &lock->fl, &conflock->fl)) {
432                 dprintk("lockd: conflicting lock(ty=%d, %Ld-%Ld)\n",
433                                 conflock->fl.fl_type,
434                                 (long long)conflock->fl.fl_start,
435                                 (long long)conflock->fl.fl_end);
436                 conflock->caller = "somehost";  /* FIXME */
437                 conflock->oh.len = 0;           /* don't return OH info */
438                 conflock->svid = conflock->fl.fl_pid;
439                 return nlm_lck_denied;
440         }
441
442         return nlm_granted;
443 }
444
445 /*
446  * Remove a lock.
447  * This implies a CANCEL call: We send a GRANT_MSG, the client replies
448  * with a GRANT_RES call which gets lost, and calls UNLOCK immediately
449  * afterwards. In this case the block will still be there, and hence
450  * must be removed.
451  */
452 u32
453 nlmsvc_unlock(struct nlm_file *file, struct nlm_lock *lock)
454 {
455         int     error;
456
457         dprintk("lockd: nlmsvc_unlock(%s/%ld, pi=%d, %Ld-%Ld)\n",
458                                 file->f_file->f_dentry->d_inode->i_sb->s_id,
459                                 file->f_file->f_dentry->d_inode->i_ino,
460                                 lock->fl.fl_pid,
461                                 (long long)lock->fl.fl_start,
462                                 (long long)lock->fl.fl_end);
463
464         /* First, cancel any lock that might be there */
465         nlmsvc_cancel_blocked(file, lock);
466
467         lock->fl.fl_type = F_UNLCK;
468         error = posix_lock_file(file->f_file, &lock->fl);
469
470         return (error < 0)? nlm_lck_denied_nolocks : nlm_granted;
471 }
472
473 /*
474  * Cancel a previously blocked request.
475  *
476  * A cancel request always overrides any grant that may currently
477  * be in progress.
478  * The calling procedure must check whether the file can be closed.
479  */
480 u32
481 nlmsvc_cancel_blocked(struct nlm_file *file, struct nlm_lock *lock)
482 {
483         struct nlm_block        *block;
484         int status = 0;
485
486         dprintk("lockd: nlmsvc_cancel(%s/%ld, pi=%d, %Ld-%Ld)\n",
487                                 file->f_file->f_dentry->d_inode->i_sb->s_id,
488                                 file->f_file->f_dentry->d_inode->i_ino,
489                                 lock->fl.fl_pid,
490                                 (long long)lock->fl.fl_start,
491                                 (long long)lock->fl.fl_end);
492
493         down(&file->f_sema);
494         if ((block = nlmsvc_lookup_block(file, lock, 1)) != NULL) {
495                 status = nlmsvc_unlink_block(block);
496                 nlmsvc_release_block(block);
497         }
498         up(&file->f_sema);
499         return status ? nlm_lck_denied : nlm_granted;
500 }
501
502 /*
503  * Unblock a blocked lock request. This is a callback invoked from the
504  * VFS layer when a lock on which we blocked is removed.
505  *
506  * This function doesn't grant the blocked lock instantly, but rather moves
507  * the block to the head of nlm_blocked where it can be picked up by lockd.
508  */
509 static void
510 nlmsvc_notify_blocked(struct file_lock *fl)
511 {
512         struct nlm_block        **bp, *block;
513
514         dprintk("lockd: VFS unblock notification for block %p\n", fl);
515         for (bp = &nlm_blocked; (block = *bp) != 0; bp = &block->b_next) {
516                 if (nlm_compare_locks(&block->b_call->a_args.lock.fl, fl)) {
517                         nlmsvc_insert_block(block, 0);
518                         svc_wake_up(block->b_daemon);
519                         return;
520                 }
521         }
522
523         printk(KERN_WARNING "lockd: notification for unknown block!\n");
524 }
525
526 static int nlmsvc_same_owner(struct file_lock *fl1, struct file_lock *fl2)
527 {
528         return fl1->fl_owner == fl2->fl_owner && fl1->fl_pid == fl2->fl_pid;
529 }
530
531 struct lock_manager_operations nlmsvc_lock_operations = {
532         .fl_compare_owner = nlmsvc_same_owner,
533         .fl_notify = nlmsvc_notify_blocked,
534 };
535
536 /*
537  * Try to claim a lock that was previously blocked.
538  *
539  * Note that we use both the RPC_GRANTED_MSG call _and_ an async
540  * RPC thread when notifying the client. This seems like overkill...
541  * Here's why:
542  *  -   we don't want to use a synchronous RPC thread, otherwise
543  *      we might find ourselves hanging on a dead portmapper.
544  *  -   Some lockd implementations (e.g. HP) don't react to
545  *      RPC_GRANTED calls; they seem to insist on RPC_GRANTED_MSG calls.
546  */
547 static void
548 nlmsvc_grant_blocked(struct nlm_block *block)
549 {
550         struct nlm_file         *file = block->b_file;
551         struct nlm_lock         *lock = &block->b_call->a_args.lock;
552         int                     error;
553
554         dprintk("lockd: grant blocked lock %p\n", block);
555
556         /* First thing is lock the file */
557         down(&file->f_sema);
558
559         /* Unlink block request from list */
560         nlmsvc_unlink_block(block);
561
562         /* If b_granted is true this means we've been here before.
563          * Just retry the grant callback, possibly refreshing the RPC
564          * binding */
565         if (block->b_granted) {
566                 nlm_rebind_host(block->b_host);
567                 goto callback;
568         }
569
570         /* Try the lock operation again */
571         lock->fl.fl_flags |= FL_SLEEP;
572         error = posix_lock_file(file->f_file, &lock->fl);
573         lock->fl.fl_flags &= ~FL_SLEEP;
574
575         switch (error) {
576         case 0:
577                 break;
578         case -EAGAIN:
579                 dprintk("lockd: lock still blocked\n");
580                 nlmsvc_insert_block(block, NLM_NEVER);
581                 goto out_unlock;
582         default:
583                 printk(KERN_WARNING "lockd: unexpected error %d in %s!\n",
584                                 -error, __FUNCTION__);
585                 nlmsvc_insert_block(block, 10 * HZ);
586                 goto out_unlock;
587         }
588
589 callback:
590         /* Lock was granted by VFS. */
591         dprintk("lockd: GRANTing blocked lock.\n");
592         block->b_granted = 1;
593
594         /* Schedule next grant callback in 30 seconds */
595         nlmsvc_insert_block(block, 30 * HZ);
596
597         /* Call the client */
598         kref_get(&block->b_count);
599         if (nlm_async_call(block->b_call, NLMPROC_GRANTED_MSG,
600                                                 &nlmsvc_grant_ops) < 0)
601                 nlmsvc_release_block(block);
602 out_unlock:
603         up(&file->f_sema);
604 }
605
606 /*
607  * This is the callback from the RPC layer when the NLM_GRANTED_MSG
608  * RPC call has succeeded or timed out.
609  * Like all RPC callbacks, it is invoked by the rpciod process, so it
610  * better not sleep. Therefore, we put the blocked lock on the nlm_blocked
611  * chain once more in order to have it removed by lockd itself (which can
612  * then sleep on the file semaphore without disrupting e.g. the nfs client).
613  */
614 static void nlmsvc_grant_callback(struct rpc_task *task, void *data)
615 {
616         struct nlm_rqst         *call = data;
617         struct nlm_block        *block = call->a_block;
618         unsigned long           timeout;
619
620         dprintk("lockd: GRANT_MSG RPC callback\n");
621
622         /* Technically, we should down the file semaphore here. Since we
623          * move the block towards the head of the queue only, no harm
624          * can be done, though. */
625         if (task->tk_status < 0) {
626                 /* RPC error: Re-insert for retransmission */
627                 timeout = 10 * HZ;
628         } else if (block->b_done) {
629                 /* Block already removed, kill it for real */
630                 timeout = 0;
631         } else {
632                 /* Call was successful, now wait for client callback */
633                 timeout = 60 * HZ;
634         }
635         nlmsvc_insert_block(block, timeout);
636         svc_wake_up(block->b_daemon);
637 }
638
639 void nlmsvc_grant_release(void *data)
640 {
641         nlmsvc_release_block(data);
642 }
643
644 static const struct rpc_call_ops nlmsvc_grant_ops = {
645         .rpc_call_done = nlmsvc_grant_callback,
646         .rpc_release = nlmsvc_grant_release,
647 };
648
649 /*
650  * We received a GRANT_RES callback. Try to find the corresponding
651  * block.
652  */
653 void
654 nlmsvc_grant_reply(struct svc_rqst *rqstp, struct nlm_cookie *cookie, u32 status)
655 {
656         struct nlm_block        *block;
657         struct nlm_file         *file;
658
659         dprintk("grant_reply: looking for cookie %x, host (%08x), s=%d \n", 
660                 *(unsigned int *)(cookie->data), 
661                 ntohl(rqstp->rq_addr.sin_addr.s_addr), status);
662         if (!(block = nlmsvc_find_block(cookie, &rqstp->rq_addr)))
663                 return;
664         file = block->b_file;
665
666         file->f_count++;
667         down(&file->f_sema);
668         if (block) {
669                 if (status == NLM_LCK_DENIED_GRACE_PERIOD) {
670                         /* Try again in a couple of seconds */
671                         nlmsvc_insert_block(block, 10 * HZ);
672                 } else {
673                         /* Lock is now held by client, or has been rejected.
674                          * In both cases, the block should be removed. */
675                         nlmsvc_unlink_block(block);
676                 }
677         }
678         up(&file->f_sema);
679         nlm_release_file(file);
680         nlmsvc_release_block(block);
681 }
682
683 /*
684  * Retry all blocked locks that have been notified. This is where lockd
685  * picks up locks that can be granted, or grant notifications that must
686  * be retransmitted.
687  */
688 unsigned long
689 nlmsvc_retry_blocked(void)
690 {
691         struct nlm_block        *block;
692
693         dprintk("nlmsvc_retry_blocked(%p, when=%ld)\n",
694                         nlm_blocked,
695                         nlm_blocked? nlm_blocked->b_when : 0);
696         while ((block = nlm_blocked) != 0) {
697                 if (block->b_when == NLM_NEVER)
698                         break;
699                 if (time_after(block->b_when,jiffies))
700                         break;
701                 dprintk("nlmsvc_retry_blocked(%p, when=%ld, done=%d)\n",
702                         block, block->b_when, block->b_done);
703                 kref_get(&block->b_count);
704                 if (block->b_done)
705                         nlmsvc_unlink_block(block);
706                 else
707                         nlmsvc_grant_blocked(block);
708                 nlmsvc_release_block(block);
709         }
710
711         if ((block = nlm_blocked) && block->b_when != NLM_NEVER)
712                 return (block->b_when - jiffies);
713
714         return MAX_SCHEDULE_TIMEOUT;
715 }