7ab2e60c51f7d44cf3c367cc267de516f8e62974
[powerpc.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/types.h>
24 #include <linux/errno.h>
25 #include <linux/kernel.h>
26 #include <linux/sched.h>
27 #include <linux/smp_lock.h>
28 #include <linux/sunrpc/clnt.h>
29 #include <linux/sunrpc/svc.h>
30 #include <linux/lockd/nlm.h>
31 #include <linux/lockd/lockd.h>
32
33 #define NLMDBG_FACILITY         NLMDBG_SVCLOCK
34
35 #ifdef CONFIG_LOCKD_V4
36 #define nlm_deadlock    nlm4_deadlock
37 #else
38 #define nlm_deadlock    nlm_lck_denied
39 #endif
40
41 static void nlmsvc_release_block(struct nlm_block *block);
42 static void     nlmsvc_insert_block(struct nlm_block *block, unsigned long);
43 static void     nlmsvc_remove_block(struct nlm_block *block);
44
45 static int nlmsvc_setgrantargs(struct nlm_rqst *call, struct nlm_lock *lock);
46 static void nlmsvc_freegrantargs(struct nlm_rqst *call);
47 static const struct rpc_call_ops nlmsvc_grant_ops;
48
49 /*
50  * The list of blocked locks to retry
51  */
52 static LIST_HEAD(nlm_blocked);
53
54 /*
55  * Insert a blocked lock into the global list
56  */
57 static void
58 nlmsvc_insert_block(struct nlm_block *block, unsigned long when)
59 {
60         struct nlm_block *b;
61         struct list_head *pos;
62
63         dprintk("lockd: nlmsvc_insert_block(%p, %ld)\n", block, when);
64         if (list_empty(&block->b_list)) {
65                 kref_get(&block->b_count);
66         } else {
67                 list_del_init(&block->b_list);
68         }
69
70         pos = &nlm_blocked;
71         if (when != NLM_NEVER) {
72                 if ((when += jiffies) == NLM_NEVER)
73                         when ++;
74                 list_for_each(pos, &nlm_blocked) {
75                         b = list_entry(pos, struct nlm_block, b_list);
76                         if (time_after(b->b_when,when) || b->b_when == NLM_NEVER)
77                                 break;
78                 }
79                 /* On normal exit from the loop, pos == &nlm_blocked,
80                  * so we will be adding to the end of the list - good
81                  */
82         }
83
84         list_add_tail(&block->b_list, pos);
85         block->b_when = when;
86 }
87
88 /*
89  * Remove a block from the global list
90  */
91 static inline void
92 nlmsvc_remove_block(struct nlm_block *block)
93 {
94         if (!list_empty(&block->b_list)) {
95                 list_del_init(&block->b_list);
96                 nlmsvc_release_block(block);
97         }
98 }
99
100 /*
101  * Find a block for a given lock
102  */
103 static struct nlm_block *
104 nlmsvc_lookup_block(struct nlm_file *file, struct nlm_lock *lock)
105 {
106         struct nlm_block        *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         list_for_each_entry(block, &nlm_blocked, b_list) {
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                         kref_get(&block->b_count);
122                         return block;
123                 }
124         }
125
126         return NULL;
127 }
128
129 static inline int nlm_cookie_match(struct nlm_cookie *a, struct nlm_cookie *b)
130 {
131         if(a->len != b->len)
132                 return 0;
133         if(memcmp(a->data,b->data,a->len))
134                 return 0;
135         return 1;
136 }
137
138 /*
139  * Find a block with a given NLM cookie.
140  */
141 static inline struct nlm_block *
142 nlmsvc_find_block(struct nlm_cookie *cookie)
143 {
144         struct nlm_block *block;
145
146         list_for_each_entry(block, &nlm_blocked, b_list) {
147                 if (nlm_cookie_match(&block->b_call->a_args.cookie,cookie))
148                         goto found;
149         }
150
151         return NULL;
152
153 found:
154         dprintk("nlmsvc_find_block(%s): block=%p\n", nlmdbg_cookie2a(cookie), block);
155         kref_get(&block->b_count);
156         return block;
157 }
158
159 /*
160  * Create a block and initialize it.
161  *
162  * Note: we explicitly set the cookie of the grant reply to that of
163  * the blocked lock request. The spec explicitly mentions that the client
164  * should _not_ rely on the callback containing the same cookie as the
165  * request, but (as I found out later) that's because some implementations
166  * do just this. Never mind the standards comittees, they support our
167  * logging industries.
168  *
169  * 10 years later: I hope we can safely ignore these old and broken
170  * clients by now. Let's fix this so we can uniquely identify an incoming
171  * GRANTED_RES message by cookie, without having to rely on the client's IP
172  * address. --okir
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, lock->caller, lock->len);
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         INIT_LIST_HEAD(&block->b_list);
197         INIT_LIST_HEAD(&block->b_flist);
198
199         if (!nlmsvc_setgrantargs(call, lock))
200                 goto failed_free;
201
202         /* Set notifier function for VFS, and init args */
203         call->a_args.lock.fl.fl_flags |= FL_SLEEP;
204         call->a_args.lock.fl.fl_lmops = &nlmsvc_lock_operations;
205         nlmclnt_next_cookie(&call->a_args.cookie);
206
207         dprintk("lockd: created block %p...\n", block);
208
209         /* Create and initialize the block */
210         block->b_daemon = rqstp->rq_server;
211         block->b_host   = host;
212         block->b_file   = file;
213         file->f_count++;
214
215         /* Add to file's list of blocks */
216         list_add(&block->b_flist, &file->f_blocks);
217
218         /* Set up RPC arguments for callback */
219         block->b_call = call;
220         call->a_flags   = RPC_TASK_ASYNC;
221         call->a_block = block;
222
223         return block;
224
225 failed_free:
226         kfree(block);
227 failed:
228         nlm_release_call(call);
229         return NULL;
230 }
231
232 /*
233  * Delete a block. If the lock was cancelled or the grant callback
234  * failed, unlock is set to 1.
235  * It is the caller's responsibility to check whether the file
236  * can be closed hereafter.
237  */
238 static int nlmsvc_unlink_block(struct nlm_block *block)
239 {
240         int status;
241         dprintk("lockd: unlinking block %p...\n", block);
242
243         /* Remove block from list */
244         status = posix_unblock_lock(block->b_file->f_file, &block->b_call->a_args.lock.fl);
245         nlmsvc_remove_block(block);
246         return status;
247 }
248
249 static void nlmsvc_free_block(struct kref *kref)
250 {
251         struct nlm_block *block = container_of(kref, struct nlm_block, b_count);
252         struct nlm_file         *file = block->b_file;
253
254         dprintk("lockd: freeing block %p...\n", block);
255
256         /* Remove block from file's list of blocks */
257         mutex_lock(&file->f_mutex);
258         list_del_init(&block->b_flist);
259         mutex_unlock(&file->f_mutex);
260
261         nlmsvc_freegrantargs(block->b_call);
262         nlm_release_call(block->b_call);
263         nlm_release_file(block->b_file);
264         kfree(block->b_fl);
265         kfree(block);
266 }
267
268 static void nlmsvc_release_block(struct nlm_block *block)
269 {
270         if (block != NULL)
271                 kref_put(&block->b_count, nlmsvc_free_block);
272 }
273
274 /*
275  * Loop over all blocks and delete blocks held by
276  * a matching host.
277  */
278 void nlmsvc_traverse_blocks(struct nlm_host *host,
279                         struct nlm_file *file,
280                         nlm_host_match_fn_t match)
281 {
282         struct nlm_block *block, *next;
283
284 restart:
285         mutex_lock(&file->f_mutex);
286         list_for_each_entry_safe(block, next, &file->f_blocks, b_flist) {
287                 if (!match(block->b_host, host))
288                         continue;
289                 /* Do not destroy blocks that are not on
290                  * the global retry list - why? */
291                 if (list_empty(&block->b_list))
292                         continue;
293                 kref_get(&block->b_count);
294                 mutex_unlock(&file->f_mutex);
295                 nlmsvc_unlink_block(block);
296                 nlmsvc_release_block(block);
297                 goto restart;
298         }
299         mutex_unlock(&file->f_mutex);
300 }
301
302 /*
303  * Initialize arguments for GRANTED call. The nlm_rqst structure
304  * has been cleared already.
305  */
306 static int nlmsvc_setgrantargs(struct nlm_rqst *call, struct nlm_lock *lock)
307 {
308         locks_copy_lock(&call->a_args.lock.fl, &lock->fl);
309         memcpy(&call->a_args.lock.fh, &lock->fh, sizeof(call->a_args.lock.fh));
310         call->a_args.lock.caller = utsname()->nodename;
311         call->a_args.lock.oh.len = lock->oh.len;
312
313         /* set default data area */
314         call->a_args.lock.oh.data = call->a_owner;
315         call->a_args.lock.svid = lock->fl.fl_pid;
316
317         if (lock->oh.len > NLMCLNT_OHSIZE) {
318                 void *data = kmalloc(lock->oh.len, GFP_KERNEL);
319                 if (!data)
320                         return 0;
321                 call->a_args.lock.oh.data = (u8 *) data;
322         }
323
324         memcpy(call->a_args.lock.oh.data, lock->oh.data, lock->oh.len);
325         return 1;
326 }
327
328 static void nlmsvc_freegrantargs(struct nlm_rqst *call)
329 {
330         if (call->a_args.lock.oh.data != call->a_owner)
331                 kfree(call->a_args.lock.oh.data);
332 }
333
334 /*
335  * Deferred lock request handling for non-blocking lock
336  */
337 static u32
338 nlmsvc_defer_lock_rqst(struct svc_rqst *rqstp, struct nlm_block *block)
339 {
340         u32 status = nlm_lck_denied_nolocks;
341
342         block->b_flags |= B_QUEUED;
343
344         nlmsvc_insert_block(block, NLM_TIMEOUT);
345
346         block->b_cache_req = &rqstp->rq_chandle;
347         if (rqstp->rq_chandle.defer) {
348                 block->b_deferred_req =
349                         rqstp->rq_chandle.defer(block->b_cache_req);
350                 if (block->b_deferred_req != NULL)
351                         status = nlm_drop_reply;
352         }
353         dprintk("lockd: nlmsvc_defer_lock_rqst block %p flags %d status %d\n",
354                 block, block->b_flags, status);
355
356         return status;
357 }
358
359 /*
360  * Attempt to establish a lock, and if it can't be granted, block it
361  * if required.
362  */
363 __be32
364 nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file,
365                         struct nlm_lock *lock, int wait, struct nlm_cookie *cookie)
366 {
367         struct nlm_block        *block, *newblock = NULL;
368         int                     error;
369         __be32                  ret;
370
371         dprintk("lockd: nlmsvc_lock(%s/%ld, ty=%d, pi=%d, %Ld-%Ld, bl=%d)\n",
372                                 file->f_file->f_path.dentry->d_inode->i_sb->s_id,
373                                 file->f_file->f_path.dentry->d_inode->i_ino,
374                                 lock->fl.fl_type, lock->fl.fl_pid,
375                                 (long long)lock->fl.fl_start,
376                                 (long long)lock->fl.fl_end,
377                                 wait);
378
379
380         lock->fl.fl_flags &= ~FL_SLEEP;
381 again:
382         /* Lock file against concurrent access */
383         mutex_lock(&file->f_mutex);
384         /* Get existing block (in case client is busy-waiting) */
385         block = nlmsvc_lookup_block(file, lock);
386         if (block == NULL) {
387                 if (newblock != NULL)
388                         lock = &newblock->b_call->a_args.lock;
389         } else
390                 lock = &block->b_call->a_args.lock;
391
392         error = posix_lock_file(file->f_file, &lock->fl, NULL);
393         lock->fl.fl_flags &= ~FL_SLEEP;
394
395         dprintk("lockd: posix_lock_file returned %d\n", error);
396
397         switch(error) {
398                 case 0:
399                         ret = nlm_granted;
400                         goto out;
401                 case -EAGAIN:
402                         break;
403                 case -EDEADLK:
404                         ret = nlm_deadlock;
405                         goto out;
406                 default:                        /* includes ENOLCK */
407                         ret = nlm_lck_denied_nolocks;
408                         goto out;
409         }
410
411         ret = nlm_lck_denied;
412         if (!wait)
413                 goto out;
414
415         ret = nlm_lck_blocked;
416         if (block != NULL)
417                 goto out;
418
419         /* If we don't have a block, create and initialize it. Then
420          * retry because we may have slept in kmalloc. */
421         /* We have to release f_mutex as nlmsvc_create_block may try to
422          * to claim it while doing host garbage collection */
423         if (newblock == NULL) {
424                 mutex_unlock(&file->f_mutex);
425                 dprintk("lockd: blocking on this lock (allocating).\n");
426                 if (!(newblock = nlmsvc_create_block(rqstp, file, lock, cookie)))
427                         return nlm_lck_denied_nolocks;
428                 goto again;
429         }
430
431         /* Append to list of blocked */
432         nlmsvc_insert_block(newblock, NLM_NEVER);
433 out:
434         mutex_unlock(&file->f_mutex);
435         nlmsvc_release_block(newblock);
436         nlmsvc_release_block(block);
437         dprintk("lockd: nlmsvc_lock returned %u\n", ret);
438         return ret;
439 }
440
441 /*
442  * Test for presence of a conflicting lock.
443  */
444 __be32
445 nlmsvc_testlock(struct svc_rqst *rqstp, struct nlm_file *file,
446                 struct nlm_lock *lock, struct nlm_lock *conflock,
447                 struct nlm_cookie *cookie)
448 {
449         dprintk("lockd: nlmsvc_testlock(%s/%ld, ty=%d, %Ld-%Ld)\n",
450                                 file->f_file->f_path.dentry->d_inode->i_sb->s_id,
451                                 file->f_file->f_path.dentry->d_inode->i_ino,
452                                 lock->fl.fl_type,
453                                 (long long)lock->fl.fl_start,
454                                 (long long)lock->fl.fl_end);
455
456         if (posix_test_lock(file->f_file, &lock->fl)) {
457                 dprintk("lockd: conflicting lock(ty=%d, %Ld-%Ld)\n",
458                                 lock->fl.fl_type,
459                                 (long long)lock->fl.fl_start,
460                                 (long long)lock->fl.fl_end);
461                 conflock->caller = "somehost";  /* FIXME */
462                 conflock->len = strlen(conflock->caller);
463                 conflock->oh.len = 0;           /* don't return OH info */
464                 conflock->svid = lock->fl.fl_pid;
465                 conflock->fl.fl_type = lock->fl.fl_type;
466                 conflock->fl.fl_start = lock->fl.fl_start;
467                 conflock->fl.fl_end = lock->fl.fl_end;
468                 return nlm_lck_denied;
469         }
470
471         return nlm_granted;
472 }
473
474 /*
475  * Remove a lock.
476  * This implies a CANCEL call: We send a GRANT_MSG, the client replies
477  * with a GRANT_RES call which gets lost, and calls UNLOCK immediately
478  * afterwards. In this case the block will still be there, and hence
479  * must be removed.
480  */
481 __be32
482 nlmsvc_unlock(struct nlm_file *file, struct nlm_lock *lock)
483 {
484         int     error;
485
486         dprintk("lockd: nlmsvc_unlock(%s/%ld, pi=%d, %Ld-%Ld)\n",
487                                 file->f_file->f_path.dentry->d_inode->i_sb->s_id,
488                                 file->f_file->f_path.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         /* First, cancel any lock that might be there */
494         nlmsvc_cancel_blocked(file, lock);
495
496         lock->fl.fl_type = F_UNLCK;
497         error = posix_lock_file(file->f_file, &lock->fl, NULL);
498
499         return (error < 0)? nlm_lck_denied_nolocks : nlm_granted;
500 }
501
502 /*
503  * Cancel a previously blocked request.
504  *
505  * A cancel request always overrides any grant that may currently
506  * be in progress.
507  * The calling procedure must check whether the file can be closed.
508  */
509 __be32
510 nlmsvc_cancel_blocked(struct nlm_file *file, struct nlm_lock *lock)
511 {
512         struct nlm_block        *block;
513         int status = 0;
514
515         dprintk("lockd: nlmsvc_cancel(%s/%ld, pi=%d, %Ld-%Ld)\n",
516                                 file->f_file->f_path.dentry->d_inode->i_sb->s_id,
517                                 file->f_file->f_path.dentry->d_inode->i_ino,
518                                 lock->fl.fl_pid,
519                                 (long long)lock->fl.fl_start,
520                                 (long long)lock->fl.fl_end);
521
522         mutex_lock(&file->f_mutex);
523         block = nlmsvc_lookup_block(file, lock);
524         mutex_unlock(&file->f_mutex);
525         if (block != NULL) {
526                 status = nlmsvc_unlink_block(block);
527                 nlmsvc_release_block(block);
528         }
529         return status ? nlm_lck_denied : nlm_granted;
530 }
531
532 /*
533  * This is a callback from the filesystem for VFS file lock requests.
534  * It will be used if fl_grant is defined and the filesystem can not
535  * respond to the request immediately.
536  * For GETLK request it will copy the reply to the nlm_block.
537  * For SETLK or SETLKW request it will get the local posix lock.
538  * In all cases it will move the block to the head of nlm_blocked q where
539  * nlmsvc_retry_blocked() can send back a reply for SETLKW or revisit the
540  * deferred rpc for GETLK and SETLK.
541  */
542 static void
543 nlmsvc_update_deferred_block(struct nlm_block *block, struct file_lock *conf,
544                              int result)
545 {
546         block->b_flags |= B_GOT_CALLBACK;
547         if (result == 0)
548                 block->b_granted = 1;
549         else
550                 block->b_flags |= B_TIMED_OUT;
551         if (conf) {
552                 block->b_fl = kzalloc(sizeof(struct file_lock), GFP_KERNEL);
553                 if (block->b_fl)
554                         locks_copy_lock(block->b_fl, conf);
555         }
556 }
557
558 static int nlmsvc_grant_deferred(struct file_lock *fl, struct file_lock *conf,
559                                         int result)
560 {
561         struct nlm_block *block;
562         int rc = -ENOENT;
563
564         lock_kernel();
565         list_for_each_entry(block, &nlm_blocked, b_list) {
566                 if (nlm_compare_locks(&block->b_call->a_args.lock.fl, fl)) {
567                         dprintk("lockd: nlmsvc_notify_blocked block %p flags %d\n",
568                                                         block, block->b_flags);
569                         if (block->b_flags & B_QUEUED) {
570                                 if (block->b_flags & B_TIMED_OUT) {
571                                         rc = -ENOLCK;
572                                         break;
573                                 }
574                                 nlmsvc_update_deferred_block(block, conf, result);
575                         } else if (result == 0)
576                                 block->b_granted = 1;
577
578                         nlmsvc_insert_block(block, 0);
579                         svc_wake_up(block->b_daemon);
580                         rc = 0;
581                         break;
582                 }
583         }
584         unlock_kernel();
585         if (rc == -ENOENT)
586                 printk(KERN_WARNING "lockd: grant for unknown block\n");
587         return rc;
588 }
589
590 /*
591  * Unblock a blocked lock request. This is a callback invoked from the
592  * VFS layer when a lock on which we blocked is removed.
593  *
594  * This function doesn't grant the blocked lock instantly, but rather moves
595  * the block to the head of nlm_blocked where it can be picked up by lockd.
596  */
597 static void
598 nlmsvc_notify_blocked(struct file_lock *fl)
599 {
600         struct nlm_block        *block;
601
602         dprintk("lockd: VFS unblock notification for block %p\n", fl);
603         list_for_each_entry(block, &nlm_blocked, b_list) {
604                 if (nlm_compare_locks(&block->b_call->a_args.lock.fl, fl)) {
605                         nlmsvc_insert_block(block, 0);
606                         svc_wake_up(block->b_daemon);
607                         return;
608                 }
609         }
610
611         printk(KERN_WARNING "lockd: notification for unknown block!\n");
612 }
613
614 static int nlmsvc_same_owner(struct file_lock *fl1, struct file_lock *fl2)
615 {
616         return fl1->fl_owner == fl2->fl_owner && fl1->fl_pid == fl2->fl_pid;
617 }
618
619 struct lock_manager_operations nlmsvc_lock_operations = {
620         .fl_compare_owner = nlmsvc_same_owner,
621         .fl_notify = nlmsvc_notify_blocked,
622         .fl_grant = nlmsvc_grant_deferred,
623 };
624
625 /*
626  * Try to claim a lock that was previously blocked.
627  *
628  * Note that we use both the RPC_GRANTED_MSG call _and_ an async
629  * RPC thread when notifying the client. This seems like overkill...
630  * Here's why:
631  *  -   we don't want to use a synchronous RPC thread, otherwise
632  *      we might find ourselves hanging on a dead portmapper.
633  *  -   Some lockd implementations (e.g. HP) don't react to
634  *      RPC_GRANTED calls; they seem to insist on RPC_GRANTED_MSG calls.
635  */
636 static void
637 nlmsvc_grant_blocked(struct nlm_block *block)
638 {
639         struct nlm_file         *file = block->b_file;
640         struct nlm_lock         *lock = &block->b_call->a_args.lock;
641         int                     error;
642
643         dprintk("lockd: grant blocked lock %p\n", block);
644
645         kref_get(&block->b_count);
646
647         /* Unlink block request from list */
648         nlmsvc_unlink_block(block);
649
650         /* If b_granted is true this means we've been here before.
651          * Just retry the grant callback, possibly refreshing the RPC
652          * binding */
653         if (block->b_granted) {
654                 nlm_rebind_host(block->b_host);
655                 goto callback;
656         }
657
658         /* Try the lock operation again */
659         lock->fl.fl_flags |= FL_SLEEP;
660         error = posix_lock_file(file->f_file, &lock->fl, NULL);
661         lock->fl.fl_flags &= ~FL_SLEEP;
662
663         switch (error) {
664         case 0:
665                 break;
666         case -EAGAIN:
667                 dprintk("lockd: lock still blocked\n");
668                 nlmsvc_insert_block(block, NLM_NEVER);
669                 nlmsvc_release_block(block);
670                 return;
671         default:
672                 printk(KERN_WARNING "lockd: unexpected error %d in %s!\n",
673                                 -error, __FUNCTION__);
674                 nlmsvc_insert_block(block, 10 * HZ);
675                 nlmsvc_release_block(block);
676                 return;
677         }
678
679 callback:
680         /* Lock was granted by VFS. */
681         dprintk("lockd: GRANTing blocked lock.\n");
682         block->b_granted = 1;
683
684         /* Schedule next grant callback in 30 seconds */
685         nlmsvc_insert_block(block, 30 * HZ);
686
687         /* Call the client */
688         nlm_async_call(block->b_call, NLMPROC_GRANTED_MSG, &nlmsvc_grant_ops);
689 }
690
691 /*
692  * This is the callback from the RPC layer when the NLM_GRANTED_MSG
693  * RPC call has succeeded or timed out.
694  * Like all RPC callbacks, it is invoked by the rpciod process, so it
695  * better not sleep. Therefore, we put the blocked lock on the nlm_blocked
696  * chain once more in order to have it removed by lockd itself (which can
697  * then sleep on the file semaphore without disrupting e.g. the nfs client).
698  */
699 static void nlmsvc_grant_callback(struct rpc_task *task, void *data)
700 {
701         struct nlm_rqst         *call = data;
702         struct nlm_block        *block = call->a_block;
703         unsigned long           timeout;
704
705         dprintk("lockd: GRANT_MSG RPC callback\n");
706
707         /* Technically, we should down the file semaphore here. Since we
708          * move the block towards the head of the queue only, no harm
709          * can be done, though. */
710         if (task->tk_status < 0) {
711                 /* RPC error: Re-insert for retransmission */
712                 timeout = 10 * HZ;
713         } else {
714                 /* Call was successful, now wait for client callback */
715                 timeout = 60 * HZ;
716         }
717         nlmsvc_insert_block(block, timeout);
718         svc_wake_up(block->b_daemon);
719 }
720
721 static void nlmsvc_grant_release(void *data)
722 {
723         struct nlm_rqst         *call = data;
724
725         nlmsvc_release_block(call->a_block);
726 }
727
728 static const struct rpc_call_ops nlmsvc_grant_ops = {
729         .rpc_call_done = nlmsvc_grant_callback,
730         .rpc_release = nlmsvc_grant_release,
731 };
732
733 /*
734  * We received a GRANT_RES callback. Try to find the corresponding
735  * block.
736  */
737 void
738 nlmsvc_grant_reply(struct nlm_cookie *cookie, __be32 status)
739 {
740         struct nlm_block        *block;
741
742         dprintk("grant_reply: looking for cookie %x, s=%d \n",
743                 *(unsigned int *)(cookie->data), status);
744         if (!(block = nlmsvc_find_block(cookie)))
745                 return;
746
747         if (block) {
748                 if (status == nlm_lck_denied_grace_period) {
749                         /* Try again in a couple of seconds */
750                         nlmsvc_insert_block(block, 10 * HZ);
751                 } else {
752                         /* Lock is now held by client, or has been rejected.
753                          * In both cases, the block should be removed. */
754                         nlmsvc_unlink_block(block);
755                 }
756         }
757         nlmsvc_release_block(block);
758 }
759
760 /* Helper function to handle retry of a deferred block.
761  * If it is a blocking lock, call grant_blocked.
762  * For a non-blocking lock or test lock, revisit the request.
763  */
764 static void
765 retry_deferred_block(struct nlm_block *block)
766 {
767         if (!(block->b_flags & B_GOT_CALLBACK))
768                 block->b_flags |= B_TIMED_OUT;
769         nlmsvc_insert_block(block, NLM_TIMEOUT);
770         dprintk("revisit block %p flags %d\n",  block, block->b_flags);
771         if (block->b_deferred_req) {
772                 block->b_deferred_req->revisit(block->b_deferred_req, 0);
773                 block->b_deferred_req = NULL;
774         }
775 }
776
777 /*
778  * Retry all blocked locks that have been notified. This is where lockd
779  * picks up locks that can be granted, or grant notifications that must
780  * be retransmitted.
781  */
782 unsigned long
783 nlmsvc_retry_blocked(void)
784 {
785         unsigned long   timeout = MAX_SCHEDULE_TIMEOUT;
786         struct nlm_block *block;
787
788         while (!list_empty(&nlm_blocked)) {
789                 block = list_entry(nlm_blocked.next, struct nlm_block, b_list);
790
791                 if (block->b_when == NLM_NEVER)
792                         break;
793                 if (time_after(block->b_when,jiffies)) {
794                         timeout = block->b_when - jiffies;
795                         break;
796                 }
797
798                 dprintk("nlmsvc_retry_blocked(%p, when=%ld)\n",
799                         block, block->b_when);
800                 if (block->b_flags & B_QUEUED) {
801                         dprintk("nlmsvc_retry_blocked delete block (%p, granted=%d, flags=%d)\n",
802                                 block, block->b_granted, block->b_flags);
803                         retry_deferred_block(block);
804                 } else
805                         nlmsvc_grant_blocked(block);
806         }
807
808         return timeout;
809 }