Merge git://git.linux-nfs.org/pub/linux/nfs-2.6
[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
107  */
108 static struct nlm_block *
109 nlmsvc_lookup_block(struct nlm_file *file, struct nlm_lock *lock)
110 {
111         struct nlm_block        **head, *block;
112         struct file_lock        *fl;
113
114         dprintk("lockd: nlmsvc_lookup_block f=%p pd=%d %Ld-%Ld ty=%d\n",
115                                 file, lock->fl.fl_pid,
116                                 (long long)lock->fl.fl_start,
117                                 (long long)lock->fl.fl_end, lock->fl.fl_type);
118         for (head = &nlm_blocked; (block = *head) != 0; head = &block->b_next) {
119                 fl = &block->b_call->a_args.lock.fl;
120                 dprintk("lockd: check f=%p pd=%d %Ld-%Ld ty=%d cookie=%s\n",
121                                 block->b_file, fl->fl_pid,
122                                 (long long)fl->fl_start,
123                                 (long long)fl->fl_end, fl->fl_type,
124                                 nlmdbg_cookie2a(&block->b_call->a_args.cookie));
125                 if (block->b_file == file && nlm_compare_locks(fl, &lock->fl)) {
126                         kref_get(&block->b_count);
127                         return block;
128                 }
129         }
130
131         return NULL;
132 }
133
134 static inline int nlm_cookie_match(struct nlm_cookie *a, struct nlm_cookie *b)
135 {
136         if(a->len != b->len)
137                 return 0;
138         if(memcmp(a->data,b->data,a->len))
139                 return 0;
140         return 1;
141 }
142
143 /*
144  * Find a block with a given NLM cookie.
145  */
146 static inline struct nlm_block *
147 nlmsvc_find_block(struct nlm_cookie *cookie,  struct sockaddr_in *sin)
148 {
149         struct nlm_block *block;
150
151         for (block = nlm_blocked; block; block = block->b_next) {
152                 dprintk("cookie: head of blocked queue %p, block %p\n", 
153                         nlm_blocked, block);
154                 if (nlm_cookie_match(&block->b_call->a_args.cookie,cookie)
155                                 && nlm_cmp_addr(sin, &block->b_host->h_addr))
156                         break;
157         }
158
159         if (block != NULL)
160                 kref_get(&block->b_count);
161         return block;
162 }
163
164 /*
165  * Create a block and initialize it.
166  *
167  * Note: we explicitly set the cookie of the grant reply to that of
168  * the blocked lock request. The spec explicitly mentions that the client
169  * should _not_ rely on the callback containing the same cookie as the
170  * request, but (as I found out later) that's because some implementations
171  * do just this. Never mind the standards comittees, they support our
172  * logging industries.
173  */
174 static inline struct nlm_block *
175 nlmsvc_create_block(struct svc_rqst *rqstp, struct nlm_file *file,
176                                 struct nlm_lock *lock, struct nlm_cookie *cookie)
177 {
178         struct nlm_block        *block;
179         struct nlm_host         *host;
180         struct nlm_rqst         *call = NULL;
181
182         /* Create host handle for callback */
183         host = nlmsvc_lookup_host(rqstp);
184         if (host == NULL)
185                 return NULL;
186
187         call = nlm_alloc_call(host);
188         if (call == NULL)
189                 return NULL;
190
191         /* Allocate memory for block, and initialize arguments */
192         block = kzalloc(sizeof(*block), GFP_KERNEL);
193         if (block == NULL)
194                 goto failed;
195         kref_init(&block->b_count);
196
197         if (!nlmsvc_setgrantargs(call, lock))
198                 goto failed_free;
199
200         /* Set notifier function for VFS, and init args */
201         call->a_args.lock.fl.fl_flags |= FL_SLEEP;
202         call->a_args.lock.fl.fl_lmops = &nlmsvc_lock_operations;
203         call->a_args.cookie = *cookie;  /* see above */
204
205         dprintk("lockd: created block %p...\n", block);
206
207         /* Create and initialize the block */
208         block->b_daemon = rqstp->rq_server;
209         block->b_host   = host;
210         block->b_file   = file;
211         file->f_count++;
212
213         /* Add to file's list of blocks */
214         block->b_fnext  = file->f_blocks;
215         file->f_blocks  = block;
216
217         /* Set up RPC arguments for callback */
218         block->b_call = call;
219         call->a_flags   = RPC_TASK_ASYNC;
220         call->a_block = block;
221
222         return block;
223
224 failed_free:
225         kfree(block);
226 failed:
227         nlm_release_call(call);
228         return NULL;
229 }
230
231 /*
232  * Delete a block. If the lock was cancelled or the grant callback
233  * failed, unlock is set to 1.
234  * It is the caller's responsibility to check whether the file
235  * can be closed hereafter.
236  */
237 static int nlmsvc_unlink_block(struct nlm_block *block)
238 {
239         int status;
240         dprintk("lockd: unlinking block %p...\n", block);
241
242         /* Remove block from list */
243         status = posix_unblock_lock(block->b_file->f_file, &block->b_call->a_args.lock.fl);
244         nlmsvc_remove_block(block);
245         return status;
246 }
247
248 static void nlmsvc_free_block(struct kref *kref)
249 {
250         struct nlm_block *block = container_of(kref, struct nlm_block, b_count);
251         struct nlm_file         *file = block->b_file;
252         struct nlm_block        **bp;
253
254         dprintk("lockd: freeing block %p...\n", block);
255
256         down(&file->f_sema);
257         /* Remove block from file's list of blocks */
258         for (bp = &file->f_blocks; *bp; bp = &(*bp)->b_fnext) {
259                 if (*bp == block) {
260                         *bp = block->b_fnext;
261                         break;
262                 }
263         }
264         up(&file->f_sema);
265
266         nlmsvc_freegrantargs(block->b_call);
267         nlm_release_call(block->b_call);
268         nlm_release_file(block->b_file);
269         kfree(block);
270 }
271
272 static void nlmsvc_release_block(struct nlm_block *block)
273 {
274         if (block != NULL)
275                 kref_put(&block->b_count, nlmsvc_free_block);
276 }
277
278 static void nlmsvc_act_mark(struct nlm_host *host, struct nlm_file *file)
279 {
280         struct nlm_block *block;
281
282         down(&file->f_sema);
283         for (block = file->f_blocks; block != NULL; block = block->b_fnext)
284                 block->b_host->h_inuse = 1;
285         up(&file->f_sema);
286 }
287
288 static void nlmsvc_act_unlock(struct nlm_host *host, struct nlm_file *file)
289 {
290         struct nlm_block *block;
291
292 restart:
293         down(&file->f_sema);
294         for (block = file->f_blocks; block != NULL; block = block->b_fnext) {
295                 if (host != NULL && host != block->b_host)
296                         continue;
297                 if (!block->b_queued)
298                         continue;
299                 kref_get(&block->b_count);
300                 up(&file->f_sema);
301                 nlmsvc_unlink_block(block);
302                 nlmsvc_release_block(block);
303                 goto restart;
304         }
305         up(&file->f_sema);
306 }
307
308 /*
309  * Loop over all blocks and perform the action specified.
310  * (NLM_ACT_CHECK handled by nlmsvc_inspect_file).
311  */
312 void
313 nlmsvc_traverse_blocks(struct nlm_host *host, struct nlm_file *file, int action)
314 {
315         if (action == NLM_ACT_MARK)
316                 nlmsvc_act_mark(host, file);
317         else
318                 nlmsvc_act_unlock(host, file);
319 }
320
321 /*
322  * Initialize arguments for GRANTED call. The nlm_rqst structure
323  * has been cleared already.
324  */
325 static int nlmsvc_setgrantargs(struct nlm_rqst *call, struct nlm_lock *lock)
326 {
327         locks_copy_lock(&call->a_args.lock.fl, &lock->fl);
328         memcpy(&call->a_args.lock.fh, &lock->fh, sizeof(call->a_args.lock.fh));
329         call->a_args.lock.caller = system_utsname.nodename;
330         call->a_args.lock.oh.len = lock->oh.len;
331
332         /* set default data area */
333         call->a_args.lock.oh.data = call->a_owner;
334         call->a_args.lock.svid = lock->fl.fl_pid;
335
336         if (lock->oh.len > NLMCLNT_OHSIZE) {
337                 void *data = kmalloc(lock->oh.len, GFP_KERNEL);
338                 if (!data)
339                         return 0;
340                 call->a_args.lock.oh.data = (u8 *) data;
341         }
342
343         memcpy(call->a_args.lock.oh.data, lock->oh.data, lock->oh.len);
344         return 1;
345 }
346
347 static void nlmsvc_freegrantargs(struct nlm_rqst *call)
348 {
349         if (call->a_args.lock.oh.data != call->a_owner)
350                 kfree(call->a_args.lock.oh.data);
351 }
352
353 /*
354  * Attempt to establish a lock, and if it can't be granted, block it
355  * if required.
356  */
357 u32
358 nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file,
359                         struct nlm_lock *lock, int wait, struct nlm_cookie *cookie)
360 {
361         struct nlm_block        *block, *newblock = NULL;
362         int                     error;
363         u32                     ret;
364
365         dprintk("lockd: nlmsvc_lock(%s/%ld, ty=%d, pi=%d, %Ld-%Ld, bl=%d)\n",
366                                 file->f_file->f_dentry->d_inode->i_sb->s_id,
367                                 file->f_file->f_dentry->d_inode->i_ino,
368                                 lock->fl.fl_type, lock->fl.fl_pid,
369                                 (long long)lock->fl.fl_start,
370                                 (long long)lock->fl.fl_end,
371                                 wait);
372
373
374         lock->fl.fl_flags &= ~FL_SLEEP;
375 again:
376         /* Lock file against concurrent access */
377         down(&file->f_sema);
378         /* Get existing block (in case client is busy-waiting) */
379         block = nlmsvc_lookup_block(file, lock);
380         if (block == NULL) {
381                 if (newblock != NULL)
382                         lock = &newblock->b_call->a_args.lock;
383         } else
384                 lock = &block->b_call->a_args.lock;
385
386         error = posix_lock_file(file->f_file, &lock->fl);
387         lock->fl.fl_flags &= ~FL_SLEEP;
388
389         dprintk("lockd: posix_lock_file returned %d\n", error);
390
391         switch(error) {
392                 case 0:
393                         ret = nlm_granted;
394                         goto out;
395                 case -EAGAIN:
396                         break;
397                 case -EDEADLK:
398                         ret = nlm_deadlock;
399                         goto out;
400                 default:                        /* includes ENOLCK */
401                         ret = nlm_lck_denied_nolocks;
402                         goto out;
403         }
404
405         ret = nlm_lck_denied;
406         if (!wait)
407                 goto out;
408
409         ret = nlm_lck_blocked;
410         if (block != NULL)
411                 goto out;
412
413         /* If we don't have a block, create and initialize it. Then
414          * retry because we may have slept in kmalloc. */
415         /* We have to release f_sema as nlmsvc_create_block may try to
416          * to claim it while doing host garbage collection */
417         if (newblock == NULL) {
418                 up(&file->f_sema);
419                 dprintk("lockd: blocking on this lock (allocating).\n");
420                 if (!(newblock = nlmsvc_create_block(rqstp, file, lock, cookie)))
421                         return nlm_lck_denied_nolocks;
422                 goto again;
423         }
424
425         /* Append to list of blocked */
426         nlmsvc_insert_block(newblock, NLM_NEVER);
427 out:
428         up(&file->f_sema);
429         nlmsvc_release_block(newblock);
430         nlmsvc_release_block(block);
431         dprintk("lockd: nlmsvc_lock returned %u\n", ret);
432         return ret;
433 }
434
435 /*
436  * Test for presence of a conflicting lock.
437  */
438 u32
439 nlmsvc_testlock(struct nlm_file *file, struct nlm_lock *lock,
440                                        struct nlm_lock *conflock)
441 {
442         dprintk("lockd: nlmsvc_testlock(%s/%ld, ty=%d, %Ld-%Ld)\n",
443                                 file->f_file->f_dentry->d_inode->i_sb->s_id,
444                                 file->f_file->f_dentry->d_inode->i_ino,
445                                 lock->fl.fl_type,
446                                 (long long)lock->fl.fl_start,
447                                 (long long)lock->fl.fl_end);
448
449         if (posix_test_lock(file->f_file, &lock->fl, &conflock->fl)) {
450                 dprintk("lockd: conflicting lock(ty=%d, %Ld-%Ld)\n",
451                                 conflock->fl.fl_type,
452                                 (long long)conflock->fl.fl_start,
453                                 (long long)conflock->fl.fl_end);
454                 conflock->caller = "somehost";  /* FIXME */
455                 conflock->oh.len = 0;           /* don't return OH info */
456                 conflock->svid = conflock->fl.fl_pid;
457                 return nlm_lck_denied;
458         }
459
460         return nlm_granted;
461 }
462
463 /*
464  * Remove a lock.
465  * This implies a CANCEL call: We send a GRANT_MSG, the client replies
466  * with a GRANT_RES call which gets lost, and calls UNLOCK immediately
467  * afterwards. In this case the block will still be there, and hence
468  * must be removed.
469  */
470 u32
471 nlmsvc_unlock(struct nlm_file *file, struct nlm_lock *lock)
472 {
473         int     error;
474
475         dprintk("lockd: nlmsvc_unlock(%s/%ld, pi=%d, %Ld-%Ld)\n",
476                                 file->f_file->f_dentry->d_inode->i_sb->s_id,
477                                 file->f_file->f_dentry->d_inode->i_ino,
478                                 lock->fl.fl_pid,
479                                 (long long)lock->fl.fl_start,
480                                 (long long)lock->fl.fl_end);
481
482         /* First, cancel any lock that might be there */
483         nlmsvc_cancel_blocked(file, lock);
484
485         lock->fl.fl_type = F_UNLCK;
486         error = posix_lock_file(file->f_file, &lock->fl);
487
488         return (error < 0)? nlm_lck_denied_nolocks : nlm_granted;
489 }
490
491 /*
492  * Cancel a previously blocked request.
493  *
494  * A cancel request always overrides any grant that may currently
495  * be in progress.
496  * The calling procedure must check whether the file can be closed.
497  */
498 u32
499 nlmsvc_cancel_blocked(struct nlm_file *file, struct nlm_lock *lock)
500 {
501         struct nlm_block        *block;
502         int status = 0;
503
504         dprintk("lockd: nlmsvc_cancel(%s/%ld, pi=%d, %Ld-%Ld)\n",
505                                 file->f_file->f_dentry->d_inode->i_sb->s_id,
506                                 file->f_file->f_dentry->d_inode->i_ino,
507                                 lock->fl.fl_pid,
508                                 (long long)lock->fl.fl_start,
509                                 (long long)lock->fl.fl_end);
510
511         down(&file->f_sema);
512         block = nlmsvc_lookup_block(file, lock);
513         up(&file->f_sema);
514         if (block != NULL) {
515                 status = nlmsvc_unlink_block(block);
516                 nlmsvc_release_block(block);
517         }
518         return status ? nlm_lck_denied : nlm_granted;
519 }
520
521 /*
522  * Unblock a blocked lock request. This is a callback invoked from the
523  * VFS layer when a lock on which we blocked is removed.
524  *
525  * This function doesn't grant the blocked lock instantly, but rather moves
526  * the block to the head of nlm_blocked where it can be picked up by lockd.
527  */
528 static void
529 nlmsvc_notify_blocked(struct file_lock *fl)
530 {
531         struct nlm_block        **bp, *block;
532
533         dprintk("lockd: VFS unblock notification for block %p\n", fl);
534         for (bp = &nlm_blocked; (block = *bp) != 0; bp = &block->b_next) {
535                 if (nlm_compare_locks(&block->b_call->a_args.lock.fl, fl)) {
536                         nlmsvc_insert_block(block, 0);
537                         svc_wake_up(block->b_daemon);
538                         return;
539                 }
540         }
541
542         printk(KERN_WARNING "lockd: notification for unknown block!\n");
543 }
544
545 static int nlmsvc_same_owner(struct file_lock *fl1, struct file_lock *fl2)
546 {
547         return fl1->fl_owner == fl2->fl_owner && fl1->fl_pid == fl2->fl_pid;
548 }
549
550 struct lock_manager_operations nlmsvc_lock_operations = {
551         .fl_compare_owner = nlmsvc_same_owner,
552         .fl_notify = nlmsvc_notify_blocked,
553 };
554
555 /*
556  * Try to claim a lock that was previously blocked.
557  *
558  * Note that we use both the RPC_GRANTED_MSG call _and_ an async
559  * RPC thread when notifying the client. This seems like overkill...
560  * Here's why:
561  *  -   we don't want to use a synchronous RPC thread, otherwise
562  *      we might find ourselves hanging on a dead portmapper.
563  *  -   Some lockd implementations (e.g. HP) don't react to
564  *      RPC_GRANTED calls; they seem to insist on RPC_GRANTED_MSG calls.
565  */
566 static void
567 nlmsvc_grant_blocked(struct nlm_block *block)
568 {
569         struct nlm_file         *file = block->b_file;
570         struct nlm_lock         *lock = &block->b_call->a_args.lock;
571         int                     error;
572
573         dprintk("lockd: grant blocked lock %p\n", block);
574
575         /* Unlink block request from list */
576         nlmsvc_unlink_block(block);
577
578         /* If b_granted is true this means we've been here before.
579          * Just retry the grant callback, possibly refreshing the RPC
580          * binding */
581         if (block->b_granted) {
582                 nlm_rebind_host(block->b_host);
583                 goto callback;
584         }
585
586         /* Try the lock operation again */
587         lock->fl.fl_flags |= FL_SLEEP;
588         error = posix_lock_file(file->f_file, &lock->fl);
589         lock->fl.fl_flags &= ~FL_SLEEP;
590
591         switch (error) {
592         case 0:
593                 break;
594         case -EAGAIN:
595                 dprintk("lockd: lock still blocked\n");
596                 nlmsvc_insert_block(block, NLM_NEVER);
597                 return;
598         default:
599                 printk(KERN_WARNING "lockd: unexpected error %d in %s!\n",
600                                 -error, __FUNCTION__);
601                 nlmsvc_insert_block(block, 10 * HZ);
602                 return;
603         }
604
605 callback:
606         /* Lock was granted by VFS. */
607         dprintk("lockd: GRANTing blocked lock.\n");
608         block->b_granted = 1;
609
610         /* Schedule next grant callback in 30 seconds */
611         nlmsvc_insert_block(block, 30 * HZ);
612
613         /* Call the client */
614         kref_get(&block->b_count);
615         if (nlm_async_call(block->b_call, NLMPROC_GRANTED_MSG,
616                                                 &nlmsvc_grant_ops) < 0)
617                 nlmsvc_release_block(block);
618 }
619
620 /*
621  * This is the callback from the RPC layer when the NLM_GRANTED_MSG
622  * RPC call has succeeded or timed out.
623  * Like all RPC callbacks, it is invoked by the rpciod process, so it
624  * better not sleep. Therefore, we put the blocked lock on the nlm_blocked
625  * chain once more in order to have it removed by lockd itself (which can
626  * then sleep on the file semaphore without disrupting e.g. the nfs client).
627  */
628 static void nlmsvc_grant_callback(struct rpc_task *task, void *data)
629 {
630         struct nlm_rqst         *call = data;
631         struct nlm_block        *block = call->a_block;
632         unsigned long           timeout;
633
634         dprintk("lockd: GRANT_MSG RPC callback\n");
635
636         /* Technically, we should down the file semaphore here. Since we
637          * move the block towards the head of the queue only, no harm
638          * can be done, though. */
639         if (task->tk_status < 0) {
640                 /* RPC error: Re-insert for retransmission */
641                 timeout = 10 * HZ;
642         } else if (block->b_done) {
643                 /* Block already removed, kill it for real */
644                 timeout = 0;
645         } else {
646                 /* Call was successful, now wait for client callback */
647                 timeout = 60 * HZ;
648         }
649         nlmsvc_insert_block(block, timeout);
650         svc_wake_up(block->b_daemon);
651 }
652
653 void nlmsvc_grant_release(void *data)
654 {
655         struct nlm_rqst         *call = data;
656
657         nlmsvc_release_block(call->a_block);
658 }
659
660 static const struct rpc_call_ops nlmsvc_grant_ops = {
661         .rpc_call_done = nlmsvc_grant_callback,
662         .rpc_release = nlmsvc_grant_release,
663 };
664
665 /*
666  * We received a GRANT_RES callback. Try to find the corresponding
667  * block.
668  */
669 void
670 nlmsvc_grant_reply(struct svc_rqst *rqstp, struct nlm_cookie *cookie, u32 status)
671 {
672         struct nlm_block        *block;
673         struct nlm_file         *file;
674
675         dprintk("grant_reply: looking for cookie %x, host (%08x), s=%d \n", 
676                 *(unsigned int *)(cookie->data), 
677                 ntohl(rqstp->rq_addr.sin_addr.s_addr), status);
678         if (!(block = nlmsvc_find_block(cookie, &rqstp->rq_addr)))
679                 return;
680         file = block->b_file;
681
682         if (block) {
683                 if (status == NLM_LCK_DENIED_GRACE_PERIOD) {
684                         /* Try again in a couple of seconds */
685                         nlmsvc_insert_block(block, 10 * HZ);
686                 } else {
687                         /* Lock is now held by client, or has been rejected.
688                          * In both cases, the block should be removed. */
689                         nlmsvc_unlink_block(block);
690                 }
691         }
692         nlmsvc_release_block(block);
693 }
694
695 /*
696  * Retry all blocked locks that have been notified. This is where lockd
697  * picks up locks that can be granted, or grant notifications that must
698  * be retransmitted.
699  */
700 unsigned long
701 nlmsvc_retry_blocked(void)
702 {
703         struct nlm_block        *block;
704
705         dprintk("nlmsvc_retry_blocked(%p, when=%ld)\n",
706                         nlm_blocked,
707                         nlm_blocked? nlm_blocked->b_when : 0);
708         while ((block = nlm_blocked) != 0) {
709                 if (block->b_when == NLM_NEVER)
710                         break;
711                 if (time_after(block->b_when,jiffies))
712                         break;
713                 dprintk("nlmsvc_retry_blocked(%p, when=%ld, done=%d)\n",
714                         block, block->b_when, block->b_done);
715                 kref_get(&block->b_count);
716                 if (block->b_done)
717                         nlmsvc_unlink_block(block);
718                 else
719                         nlmsvc_grant_blocked(block);
720                 nlmsvc_release_block(block);
721         }
722
723         if ((block = nlm_blocked) && block->b_when != NLM_NEVER)
724                 return (block->b_when - jiffies);
725
726         return MAX_SCHEDULE_TIMEOUT;
727 }