locks: Copy fl_lmops information for conflock in locks_copy_conflock()
[firefly-linux-kernel-4.4.55.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/slab.h>
25 #include <linux/errno.h>
26 #include <linux/kernel.h>
27 #include <linux/sched.h>
28 #include <linux/sunrpc/clnt.h>
29 #include <linux/sunrpc/svc_xprt.h>
30 #include <linux/lockd/nlm.h>
31 #include <linux/lockd/lockd.h>
32 #include <linux/kthread.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 void     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 LIST_HEAD(nlm_blocked);
54 static DEFINE_SPINLOCK(nlm_blocked_lock);
55
56 #ifdef LOCKD_DEBUG
57 static const char *nlmdbg_cookie2a(const struct nlm_cookie *cookie)
58 {
59         /*
60          * We can get away with a static buffer because we're only
61          * called with BKL held.
62          */
63         static char buf[2*NLM_MAXCOOKIELEN+1];
64         unsigned int i, len = sizeof(buf);
65         char *p = buf;
66
67         len--;  /* allow for trailing \0 */
68         if (len < 3)
69                 return "???";
70         for (i = 0 ; i < cookie->len ; i++) {
71                 if (len < 2) {
72                         strcpy(p-3, "...");
73                         break;
74                 }
75                 sprintf(p, "%02x", cookie->data[i]);
76                 p += 2;
77                 len -= 2;
78         }
79         *p = '\0';
80
81         return buf;
82 }
83 #endif
84
85 /*
86  * Insert a blocked lock into the global list
87  */
88 static void
89 nlmsvc_insert_block_locked(struct nlm_block *block, unsigned long when)
90 {
91         struct nlm_block *b;
92         struct list_head *pos;
93
94         dprintk("lockd: nlmsvc_insert_block(%p, %ld)\n", block, when);
95         if (list_empty(&block->b_list)) {
96                 kref_get(&block->b_count);
97         } else {
98                 list_del_init(&block->b_list);
99         }
100
101         pos = &nlm_blocked;
102         if (when != NLM_NEVER) {
103                 if ((when += jiffies) == NLM_NEVER)
104                         when ++;
105                 list_for_each(pos, &nlm_blocked) {
106                         b = list_entry(pos, struct nlm_block, b_list);
107                         if (time_after(b->b_when,when) || b->b_when == NLM_NEVER)
108                                 break;
109                 }
110                 /* On normal exit from the loop, pos == &nlm_blocked,
111                  * so we will be adding to the end of the list - good
112                  */
113         }
114
115         list_add_tail(&block->b_list, pos);
116         block->b_when = when;
117 }
118
119 static void nlmsvc_insert_block(struct nlm_block *block, unsigned long when)
120 {
121         spin_lock(&nlm_blocked_lock);
122         nlmsvc_insert_block_locked(block, when);
123         spin_unlock(&nlm_blocked_lock);
124 }
125
126 /*
127  * Remove a block from the global list
128  */
129 static inline void
130 nlmsvc_remove_block(struct nlm_block *block)
131 {
132         if (!list_empty(&block->b_list)) {
133                 spin_lock(&nlm_blocked_lock);
134                 list_del_init(&block->b_list);
135                 spin_unlock(&nlm_blocked_lock);
136                 nlmsvc_release_block(block);
137         }
138 }
139
140 /*
141  * Find a block for a given lock
142  */
143 static struct nlm_block *
144 nlmsvc_lookup_block(struct nlm_file *file, struct nlm_lock *lock)
145 {
146         struct nlm_block        *block;
147         struct file_lock        *fl;
148
149         dprintk("lockd: nlmsvc_lookup_block f=%p pd=%d %Ld-%Ld ty=%d\n",
150                                 file, lock->fl.fl_pid,
151                                 (long long)lock->fl.fl_start,
152                                 (long long)lock->fl.fl_end, lock->fl.fl_type);
153         list_for_each_entry(block, &nlm_blocked, b_list) {
154                 fl = &block->b_call->a_args.lock.fl;
155                 dprintk("lockd: check f=%p pd=%d %Ld-%Ld ty=%d cookie=%s\n",
156                                 block->b_file, fl->fl_pid,
157                                 (long long)fl->fl_start,
158                                 (long long)fl->fl_end, fl->fl_type,
159                                 nlmdbg_cookie2a(&block->b_call->a_args.cookie));
160                 if (block->b_file == file && nlm_compare_locks(fl, &lock->fl)) {
161                         kref_get(&block->b_count);
162                         return block;
163                 }
164         }
165
166         return NULL;
167 }
168
169 static inline int nlm_cookie_match(struct nlm_cookie *a, struct nlm_cookie *b)
170 {
171         if (a->len != b->len)
172                 return 0;
173         if (memcmp(a->data, b->data, a->len))
174                 return 0;
175         return 1;
176 }
177
178 /*
179  * Find a block with a given NLM cookie.
180  */
181 static inline struct nlm_block *
182 nlmsvc_find_block(struct nlm_cookie *cookie)
183 {
184         struct nlm_block *block;
185
186         list_for_each_entry(block, &nlm_blocked, b_list) {
187                 if (nlm_cookie_match(&block->b_call->a_args.cookie,cookie))
188                         goto found;
189         }
190
191         return NULL;
192
193 found:
194         dprintk("nlmsvc_find_block(%s): block=%p\n", nlmdbg_cookie2a(cookie), block);
195         kref_get(&block->b_count);
196         return block;
197 }
198
199 /*
200  * Create a block and initialize it.
201  *
202  * Note: we explicitly set the cookie of the grant reply to that of
203  * the blocked lock request. The spec explicitly mentions that the client
204  * should _not_ rely on the callback containing the same cookie as the
205  * request, but (as I found out later) that's because some implementations
206  * do just this. Never mind the standards comittees, they support our
207  * logging industries.
208  *
209  * 10 years later: I hope we can safely ignore these old and broken
210  * clients by now. Let's fix this so we can uniquely identify an incoming
211  * GRANTED_RES message by cookie, without having to rely on the client's IP
212  * address. --okir
213  */
214 static struct nlm_block *
215 nlmsvc_create_block(struct svc_rqst *rqstp, struct nlm_host *host,
216                     struct nlm_file *file, struct nlm_lock *lock,
217                     struct nlm_cookie *cookie)
218 {
219         struct nlm_block        *block;
220         struct nlm_rqst         *call = NULL;
221
222         call = nlm_alloc_call(host);
223         if (call == NULL)
224                 return NULL;
225
226         /* Allocate memory for block, and initialize arguments */
227         block = kzalloc(sizeof(*block), GFP_KERNEL);
228         if (block == NULL)
229                 goto failed;
230         kref_init(&block->b_count);
231         INIT_LIST_HEAD(&block->b_list);
232         INIT_LIST_HEAD(&block->b_flist);
233
234         if (!nlmsvc_setgrantargs(call, lock))
235                 goto failed_free;
236
237         /* Set notifier function for VFS, and init args */
238         call->a_args.lock.fl.fl_flags |= FL_SLEEP;
239         call->a_args.lock.fl.fl_lmops = &nlmsvc_lock_operations;
240         nlmclnt_next_cookie(&call->a_args.cookie);
241
242         dprintk("lockd: created block %p...\n", block);
243
244         /* Create and initialize the block */
245         block->b_daemon = rqstp->rq_server;
246         block->b_host   = host;
247         block->b_file   = file;
248         block->b_fl = NULL;
249         file->f_count++;
250
251         /* Add to file's list of blocks */
252         list_add(&block->b_flist, &file->f_blocks);
253
254         /* Set up RPC arguments for callback */
255         block->b_call = call;
256         call->a_flags   = RPC_TASK_ASYNC;
257         call->a_block = block;
258
259         return block;
260
261 failed_free:
262         kfree(block);
263 failed:
264         nlmsvc_release_call(call);
265         return NULL;
266 }
267
268 /*
269  * Delete a block.
270  * It is the caller's responsibility to check whether the file
271  * can be closed hereafter.
272  */
273 static int nlmsvc_unlink_block(struct nlm_block *block)
274 {
275         int status;
276         dprintk("lockd: unlinking block %p...\n", block);
277
278         /* Remove block from list */
279         status = posix_unblock_lock(&block->b_call->a_args.lock.fl);
280         nlmsvc_remove_block(block);
281         return status;
282 }
283
284 static void nlmsvc_free_block(struct kref *kref)
285 {
286         struct nlm_block *block = container_of(kref, struct nlm_block, b_count);
287         struct nlm_file         *file = block->b_file;
288
289         dprintk("lockd: freeing block %p...\n", block);
290
291         /* Remove block from file's list of blocks */
292         list_del_init(&block->b_flist);
293         mutex_unlock(&file->f_mutex);
294
295         nlmsvc_freegrantargs(block->b_call);
296         nlmsvc_release_call(block->b_call);
297         nlm_release_file(block->b_file);
298         kfree(block->b_fl);
299         kfree(block);
300 }
301
302 static void nlmsvc_release_block(struct nlm_block *block)
303 {
304         if (block != NULL)
305                 kref_put_mutex(&block->b_count, nlmsvc_free_block, &block->b_file->f_mutex);
306 }
307
308 /*
309  * Loop over all blocks and delete blocks held by
310  * a matching host.
311  */
312 void nlmsvc_traverse_blocks(struct nlm_host *host,
313                         struct nlm_file *file,
314                         nlm_host_match_fn_t match)
315 {
316         struct nlm_block *block, *next;
317
318 restart:
319         mutex_lock(&file->f_mutex);
320         list_for_each_entry_safe(block, next, &file->f_blocks, b_flist) {
321                 if (!match(block->b_host, host))
322                         continue;
323                 /* Do not destroy blocks that are not on
324                  * the global retry list - why? */
325                 if (list_empty(&block->b_list))
326                         continue;
327                 kref_get(&block->b_count);
328                 mutex_unlock(&file->f_mutex);
329                 nlmsvc_unlink_block(block);
330                 nlmsvc_release_block(block);
331                 goto restart;
332         }
333         mutex_unlock(&file->f_mutex);
334 }
335
336 /*
337  * Initialize arguments for GRANTED call. The nlm_rqst structure
338  * has been cleared already.
339  */
340 static int nlmsvc_setgrantargs(struct nlm_rqst *call, struct nlm_lock *lock)
341 {
342         locks_copy_lock(&call->a_args.lock.fl, &lock->fl);
343         memcpy(&call->a_args.lock.fh, &lock->fh, sizeof(call->a_args.lock.fh));
344         call->a_args.lock.caller = utsname()->nodename;
345         call->a_args.lock.oh.len = lock->oh.len;
346
347         /* set default data area */
348         call->a_args.lock.oh.data = call->a_owner;
349         call->a_args.lock.svid = lock->fl.fl_pid;
350
351         if (lock->oh.len > NLMCLNT_OHSIZE) {
352                 void *data = kmalloc(lock->oh.len, GFP_KERNEL);
353                 if (!data)
354                         return 0;
355                 call->a_args.lock.oh.data = (u8 *) data;
356         }
357
358         memcpy(call->a_args.lock.oh.data, lock->oh.data, lock->oh.len);
359         return 1;
360 }
361
362 static void nlmsvc_freegrantargs(struct nlm_rqst *call)
363 {
364         if (call->a_args.lock.oh.data != call->a_owner)
365                 kfree(call->a_args.lock.oh.data);
366
367         locks_release_private(&call->a_args.lock.fl);
368 }
369
370 /*
371  * Deferred lock request handling for non-blocking lock
372  */
373 static __be32
374 nlmsvc_defer_lock_rqst(struct svc_rqst *rqstp, struct nlm_block *block)
375 {
376         __be32 status = nlm_lck_denied_nolocks;
377
378         block->b_flags |= B_QUEUED;
379
380         nlmsvc_insert_block(block, NLM_TIMEOUT);
381
382         block->b_cache_req = &rqstp->rq_chandle;
383         if (rqstp->rq_chandle.defer) {
384                 block->b_deferred_req =
385                         rqstp->rq_chandle.defer(block->b_cache_req);
386                 if (block->b_deferred_req != NULL)
387                         status = nlm_drop_reply;
388         }
389         dprintk("lockd: nlmsvc_defer_lock_rqst block %p flags %d status %d\n",
390                 block, block->b_flags, ntohl(status));
391
392         return status;
393 }
394
395 /*
396  * Attempt to establish a lock, and if it can't be granted, block it
397  * if required.
398  */
399 __be32
400 nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file,
401             struct nlm_host *host, struct nlm_lock *lock, int wait,
402             struct nlm_cookie *cookie, int reclaim)
403 {
404         struct nlm_block        *block = NULL;
405         int                     error;
406         __be32                  ret;
407
408         dprintk("lockd: nlmsvc_lock(%s/%ld, ty=%d, pi=%d, %Ld-%Ld, bl=%d)\n",
409                                 file_inode(file->f_file)->i_sb->s_id,
410                                 file_inode(file->f_file)->i_ino,
411                                 lock->fl.fl_type, lock->fl.fl_pid,
412                                 (long long)lock->fl.fl_start,
413                                 (long long)lock->fl.fl_end,
414                                 wait);
415
416         /* Lock file against concurrent access */
417         mutex_lock(&file->f_mutex);
418         /* Get existing block (in case client is busy-waiting)
419          * or create new block
420          */
421         block = nlmsvc_lookup_block(file, lock);
422         if (block == NULL) {
423                 block = nlmsvc_create_block(rqstp, host, file, lock, cookie);
424                 ret = nlm_lck_denied_nolocks;
425                 if (block == NULL)
426                         goto out;
427                 lock = &block->b_call->a_args.lock;
428         } else
429                 lock->fl.fl_flags &= ~FL_SLEEP;
430
431         if (block->b_flags & B_QUEUED) {
432                 dprintk("lockd: nlmsvc_lock deferred block %p flags %d\n",
433                                                         block, block->b_flags);
434                 if (block->b_granted) {
435                         nlmsvc_unlink_block(block);
436                         ret = nlm_granted;
437                         goto out;
438                 }
439                 if (block->b_flags & B_TIMED_OUT) {
440                         nlmsvc_unlink_block(block);
441                         ret = nlm_lck_denied;
442                         goto out;
443                 }
444                 ret = nlm_drop_reply;
445                 goto out;
446         }
447
448         if (locks_in_grace(SVC_NET(rqstp)) && !reclaim) {
449                 ret = nlm_lck_denied_grace_period;
450                 goto out;
451         }
452         if (reclaim && !locks_in_grace(SVC_NET(rqstp))) {
453                 ret = nlm_lck_denied_grace_period;
454                 goto out;
455         }
456
457         if (!wait)
458                 lock->fl.fl_flags &= ~FL_SLEEP;
459         error = vfs_lock_file(file->f_file, F_SETLK, &lock->fl, NULL);
460         lock->fl.fl_flags &= ~FL_SLEEP;
461
462         dprintk("lockd: vfs_lock_file returned %d\n", error);
463         switch (error) {
464                 case 0:
465                         ret = nlm_granted;
466                         goto out;
467                 case -EAGAIN:
468                         /*
469                          * If this is a blocking request for an
470                          * already pending lock request then we need
471                          * to put it back on lockd's block list
472                          */
473                         if (wait)
474                                 break;
475                         ret = nlm_lck_denied;
476                         goto out;
477                 case FILE_LOCK_DEFERRED:
478                         if (wait)
479                                 break;
480                         /* Filesystem lock operation is in progress
481                            Add it to the queue waiting for callback */
482                         ret = nlmsvc_defer_lock_rqst(rqstp, block);
483                         goto out;
484                 case -EDEADLK:
485                         ret = nlm_deadlock;
486                         goto out;
487                 default:                        /* includes ENOLCK */
488                         ret = nlm_lck_denied_nolocks;
489                         goto out;
490         }
491
492         ret = nlm_lck_blocked;
493
494         /* Append to list of blocked */
495         nlmsvc_insert_block(block, NLM_NEVER);
496 out:
497         mutex_unlock(&file->f_mutex);
498         nlmsvc_release_block(block);
499         dprintk("lockd: nlmsvc_lock returned %u\n", ret);
500         return ret;
501 }
502
503 /*
504  * Test for presence of a conflicting lock.
505  */
506 __be32
507 nlmsvc_testlock(struct svc_rqst *rqstp, struct nlm_file *file,
508                 struct nlm_host *host, struct nlm_lock *lock,
509                 struct nlm_lock *conflock, struct nlm_cookie *cookie)
510 {
511         struct nlm_block        *block = NULL;
512         int                     error;
513         __be32                  ret;
514
515         dprintk("lockd: nlmsvc_testlock(%s/%ld, ty=%d, %Ld-%Ld)\n",
516                                 file_inode(file->f_file)->i_sb->s_id,
517                                 file_inode(file->f_file)->i_ino,
518                                 lock->fl.fl_type,
519                                 (long long)lock->fl.fl_start,
520                                 (long long)lock->fl.fl_end);
521
522         /* Get existing block (in case client is busy-waiting) */
523         block = nlmsvc_lookup_block(file, lock);
524
525         if (block == NULL) {
526                 struct file_lock *conf = kzalloc(sizeof(*conf), GFP_KERNEL);
527
528                 if (conf == NULL)
529                         return nlm_granted;
530                 block = nlmsvc_create_block(rqstp, host, file, lock, cookie);
531                 if (block == NULL) {
532                         kfree(conf);
533                         return nlm_granted;
534                 }
535                 block->b_fl = conf;
536         }
537         if (block->b_flags & B_QUEUED) {
538                 dprintk("lockd: nlmsvc_testlock deferred block %p flags %d fl %p\n",
539                         block, block->b_flags, block->b_fl);
540                 if (block->b_flags & B_TIMED_OUT) {
541                         nlmsvc_unlink_block(block);
542                         ret = nlm_lck_denied;
543                         goto out;
544                 }
545                 if (block->b_flags & B_GOT_CALLBACK) {
546                         nlmsvc_unlink_block(block);
547                         if (block->b_fl != NULL
548                                         && block->b_fl->fl_type != F_UNLCK) {
549                                 lock->fl = *block->b_fl;
550                                 goto conf_lock;
551                         } else {
552                                 ret = nlm_granted;
553                                 goto out;
554                         }
555                 }
556                 ret = nlm_drop_reply;
557                 goto out;
558         }
559
560         if (locks_in_grace(SVC_NET(rqstp))) {
561                 ret = nlm_lck_denied_grace_period;
562                 goto out;
563         }
564         error = vfs_test_lock(file->f_file, &lock->fl);
565         if (error == FILE_LOCK_DEFERRED) {
566                 ret = nlmsvc_defer_lock_rqst(rqstp, block);
567                 goto out;
568         }
569         if (error) {
570                 ret = nlm_lck_denied_nolocks;
571                 goto out;
572         }
573         if (lock->fl.fl_type == F_UNLCK) {
574                 ret = nlm_granted;
575                 goto out;
576         }
577
578 conf_lock:
579         dprintk("lockd: conflicting lock(ty=%d, %Ld-%Ld)\n",
580                 lock->fl.fl_type, (long long)lock->fl.fl_start,
581                 (long long)lock->fl.fl_end);
582         conflock->caller = "somehost";  /* FIXME */
583         conflock->len = strlen(conflock->caller);
584         conflock->oh.len = 0;           /* don't return OH info */
585         conflock->svid = lock->fl.fl_pid;
586         conflock->fl.fl_type = lock->fl.fl_type;
587         conflock->fl.fl_start = lock->fl.fl_start;
588         conflock->fl.fl_end = lock->fl.fl_end;
589         locks_release_private(&lock->fl);
590         ret = nlm_lck_denied;
591 out:
592         if (block)
593                 nlmsvc_release_block(block);
594         return ret;
595 }
596
597 /*
598  * Remove a lock.
599  * This implies a CANCEL call: We send a GRANT_MSG, the client replies
600  * with a GRANT_RES call which gets lost, and calls UNLOCK immediately
601  * afterwards. In this case the block will still be there, and hence
602  * must be removed.
603  */
604 __be32
605 nlmsvc_unlock(struct net *net, struct nlm_file *file, struct nlm_lock *lock)
606 {
607         int     error;
608
609         dprintk("lockd: nlmsvc_unlock(%s/%ld, pi=%d, %Ld-%Ld)\n",
610                                 file_inode(file->f_file)->i_sb->s_id,
611                                 file_inode(file->f_file)->i_ino,
612                                 lock->fl.fl_pid,
613                                 (long long)lock->fl.fl_start,
614                                 (long long)lock->fl.fl_end);
615
616         /* First, cancel any lock that might be there */
617         nlmsvc_cancel_blocked(net, file, lock);
618
619         lock->fl.fl_type = F_UNLCK;
620         error = vfs_lock_file(file->f_file, F_SETLK, &lock->fl, NULL);
621
622         return (error < 0)? nlm_lck_denied_nolocks : nlm_granted;
623 }
624
625 /*
626  * Cancel a previously blocked request.
627  *
628  * A cancel request always overrides any grant that may currently
629  * be in progress.
630  * The calling procedure must check whether the file can be closed.
631  */
632 __be32
633 nlmsvc_cancel_blocked(struct net *net, struct nlm_file *file, struct nlm_lock *lock)
634 {
635         struct nlm_block        *block;
636         int status = 0;
637
638         dprintk("lockd: nlmsvc_cancel(%s/%ld, pi=%d, %Ld-%Ld)\n",
639                                 file_inode(file->f_file)->i_sb->s_id,
640                                 file_inode(file->f_file)->i_ino,
641                                 lock->fl.fl_pid,
642                                 (long long)lock->fl.fl_start,
643                                 (long long)lock->fl.fl_end);
644
645         if (locks_in_grace(net))
646                 return nlm_lck_denied_grace_period;
647
648         mutex_lock(&file->f_mutex);
649         block = nlmsvc_lookup_block(file, lock);
650         mutex_unlock(&file->f_mutex);
651         if (block != NULL) {
652                 vfs_cancel_lock(block->b_file->f_file,
653                                 &block->b_call->a_args.lock.fl);
654                 status = nlmsvc_unlink_block(block);
655                 nlmsvc_release_block(block);
656         }
657         return status ? nlm_lck_denied : nlm_granted;
658 }
659
660 /*
661  * This is a callback from the filesystem for VFS file lock requests.
662  * It will be used if lm_grant is defined and the filesystem can not
663  * respond to the request immediately.
664  * For GETLK request it will copy the reply to the nlm_block.
665  * For SETLK or SETLKW request it will get the local posix lock.
666  * In all cases it will move the block to the head of nlm_blocked q where
667  * nlmsvc_retry_blocked() can send back a reply for SETLKW or revisit the
668  * deferred rpc for GETLK and SETLK.
669  */
670 static void
671 nlmsvc_update_deferred_block(struct nlm_block *block, int result)
672 {
673         block->b_flags |= B_GOT_CALLBACK;
674         if (result == 0)
675                 block->b_granted = 1;
676         else
677                 block->b_flags |= B_TIMED_OUT;
678 }
679
680 static int nlmsvc_grant_deferred(struct file_lock *fl, int result)
681 {
682         struct nlm_block *block;
683         int rc = -ENOENT;
684
685         spin_lock(&nlm_blocked_lock);
686         list_for_each_entry(block, &nlm_blocked, b_list) {
687                 if (nlm_compare_locks(&block->b_call->a_args.lock.fl, fl)) {
688                         dprintk("lockd: nlmsvc_notify_blocked block %p flags %d\n",
689                                                         block, block->b_flags);
690                         if (block->b_flags & B_QUEUED) {
691                                 if (block->b_flags & B_TIMED_OUT) {
692                                         rc = -ENOLCK;
693                                         break;
694                                 }
695                                 nlmsvc_update_deferred_block(block, result);
696                         } else if (result == 0)
697                                 block->b_granted = 1;
698
699                         nlmsvc_insert_block_locked(block, 0);
700                         svc_wake_up(block->b_daemon);
701                         rc = 0;
702                         break;
703                 }
704         }
705         spin_unlock(&nlm_blocked_lock);
706         if (rc == -ENOENT)
707                 printk(KERN_WARNING "lockd: grant for unknown block\n");
708         return rc;
709 }
710
711 /*
712  * Unblock a blocked lock request. This is a callback invoked from the
713  * VFS layer when a lock on which we blocked is removed.
714  *
715  * This function doesn't grant the blocked lock instantly, but rather moves
716  * the block to the head of nlm_blocked where it can be picked up by lockd.
717  */
718 static void
719 nlmsvc_notify_blocked(struct file_lock *fl)
720 {
721         struct nlm_block        *block;
722
723         dprintk("lockd: VFS unblock notification for block %p\n", fl);
724         spin_lock(&nlm_blocked_lock);
725         list_for_each_entry(block, &nlm_blocked, b_list) {
726                 if (nlm_compare_locks(&block->b_call->a_args.lock.fl, fl)) {
727                         nlmsvc_insert_block_locked(block, 0);
728                         spin_unlock(&nlm_blocked_lock);
729                         svc_wake_up(block->b_daemon);
730                         return;
731                 }
732         }
733         spin_unlock(&nlm_blocked_lock);
734         printk(KERN_WARNING "lockd: notification for unknown block!\n");
735 }
736
737 static int nlmsvc_same_owner(struct file_lock *fl1, struct file_lock *fl2)
738 {
739         return fl1->fl_owner == fl2->fl_owner && fl1->fl_pid == fl2->fl_pid;
740 }
741
742 /*
743  * Since NLM uses two "keys" for tracking locks, we need to hash them down
744  * to one for the blocked_hash. Here, we're just xor'ing the host address
745  * with the pid in order to create a key value for picking a hash bucket.
746  */
747 static unsigned long
748 nlmsvc_owner_key(struct file_lock *fl)
749 {
750         return (unsigned long)fl->fl_owner ^ (unsigned long)fl->fl_pid;
751 }
752
753 const struct lock_manager_operations nlmsvc_lock_operations = {
754         .lm_compare_owner = nlmsvc_same_owner,
755         .lm_owner_key = nlmsvc_owner_key,
756         .lm_notify = nlmsvc_notify_blocked,
757         .lm_grant = nlmsvc_grant_deferred,
758 };
759
760 /*
761  * Try to claim a lock that was previously blocked.
762  *
763  * Note that we use both the RPC_GRANTED_MSG call _and_ an async
764  * RPC thread when notifying the client. This seems like overkill...
765  * Here's why:
766  *  -   we don't want to use a synchronous RPC thread, otherwise
767  *      we might find ourselves hanging on a dead portmapper.
768  *  -   Some lockd implementations (e.g. HP) don't react to
769  *      RPC_GRANTED calls; they seem to insist on RPC_GRANTED_MSG calls.
770  */
771 static void
772 nlmsvc_grant_blocked(struct nlm_block *block)
773 {
774         struct nlm_file         *file = block->b_file;
775         struct nlm_lock         *lock = &block->b_call->a_args.lock;
776         int                     error;
777         loff_t                  fl_start, fl_end;
778
779         dprintk("lockd: grant blocked lock %p\n", block);
780
781         kref_get(&block->b_count);
782
783         /* Unlink block request from list */
784         nlmsvc_unlink_block(block);
785
786         /* If b_granted is true this means we've been here before.
787          * Just retry the grant callback, possibly refreshing the RPC
788          * binding */
789         if (block->b_granted) {
790                 nlm_rebind_host(block->b_host);
791                 goto callback;
792         }
793
794         /* Try the lock operation again */
795         /* vfs_lock_file() can mangle fl_start and fl_end, but we need
796          * them unchanged for the GRANT_MSG
797          */
798         lock->fl.fl_flags |= FL_SLEEP;
799         fl_start = lock->fl.fl_start;
800         fl_end = lock->fl.fl_end;
801         error = vfs_lock_file(file->f_file, F_SETLK, &lock->fl, NULL);
802         lock->fl.fl_flags &= ~FL_SLEEP;
803         lock->fl.fl_start = fl_start;
804         lock->fl.fl_end = fl_end;
805
806         switch (error) {
807         case 0:
808                 break;
809         case FILE_LOCK_DEFERRED:
810                 dprintk("lockd: lock still blocked error %d\n", error);
811                 nlmsvc_insert_block(block, NLM_NEVER);
812                 nlmsvc_release_block(block);
813                 return;
814         default:
815                 printk(KERN_WARNING "lockd: unexpected error %d in %s!\n",
816                                 -error, __func__);
817                 nlmsvc_insert_block(block, 10 * HZ);
818                 nlmsvc_release_block(block);
819                 return;
820         }
821
822 callback:
823         /* Lock was granted by VFS. */
824         dprintk("lockd: GRANTing blocked lock.\n");
825         block->b_granted = 1;
826
827         /* keep block on the list, but don't reattempt until the RPC
828          * completes or the submission fails
829          */
830         nlmsvc_insert_block(block, NLM_NEVER);
831
832         /* Call the client -- use a soft RPC task since nlmsvc_retry_blocked
833          * will queue up a new one if this one times out
834          */
835         error = nlm_async_call(block->b_call, NLMPROC_GRANTED_MSG,
836                                 &nlmsvc_grant_ops);
837
838         /* RPC submission failed, wait a bit and retry */
839         if (error < 0)
840                 nlmsvc_insert_block(block, 10 * HZ);
841 }
842
843 /*
844  * This is the callback from the RPC layer when the NLM_GRANTED_MSG
845  * RPC call has succeeded or timed out.
846  * Like all RPC callbacks, it is invoked by the rpciod process, so it
847  * better not sleep. Therefore, we put the blocked lock on the nlm_blocked
848  * chain once more in order to have it removed by lockd itself (which can
849  * then sleep on the file semaphore without disrupting e.g. the nfs client).
850  */
851 static void nlmsvc_grant_callback(struct rpc_task *task, void *data)
852 {
853         struct nlm_rqst         *call = data;
854         struct nlm_block        *block = call->a_block;
855         unsigned long           timeout;
856
857         dprintk("lockd: GRANT_MSG RPC callback\n");
858
859         spin_lock(&nlm_blocked_lock);
860         /* if the block is not on a list at this point then it has
861          * been invalidated. Don't try to requeue it.
862          *
863          * FIXME: it's possible that the block is removed from the list
864          * after this check but before the nlmsvc_insert_block. In that
865          * case it will be added back. Perhaps we need better locking
866          * for nlm_blocked?
867          */
868         if (list_empty(&block->b_list))
869                 goto out;
870
871         /* Technically, we should down the file semaphore here. Since we
872          * move the block towards the head of the queue only, no harm
873          * can be done, though. */
874         if (task->tk_status < 0) {
875                 /* RPC error: Re-insert for retransmission */
876                 timeout = 10 * HZ;
877         } else {
878                 /* Call was successful, now wait for client callback */
879                 timeout = 60 * HZ;
880         }
881         nlmsvc_insert_block_locked(block, timeout);
882         svc_wake_up(block->b_daemon);
883 out:
884         spin_unlock(&nlm_blocked_lock);
885 }
886
887 /*
888  * FIXME: nlmsvc_release_block() grabs a mutex.  This is not allowed for an
889  * .rpc_release rpc_call_op
890  */
891 static void nlmsvc_grant_release(void *data)
892 {
893         struct nlm_rqst         *call = data;
894         nlmsvc_release_block(call->a_block);
895 }
896
897 static const struct rpc_call_ops nlmsvc_grant_ops = {
898         .rpc_call_done = nlmsvc_grant_callback,
899         .rpc_release = nlmsvc_grant_release,
900 };
901
902 /*
903  * We received a GRANT_RES callback. Try to find the corresponding
904  * block.
905  */
906 void
907 nlmsvc_grant_reply(struct nlm_cookie *cookie, __be32 status)
908 {
909         struct nlm_block        *block;
910
911         dprintk("grant_reply: looking for cookie %x, s=%d \n",
912                 *(unsigned int *)(cookie->data), status);
913         if (!(block = nlmsvc_find_block(cookie)))
914                 return;
915
916         if (block) {
917                 if (status == nlm_lck_denied_grace_period) {
918                         /* Try again in a couple of seconds */
919                         nlmsvc_insert_block(block, 10 * HZ);
920                 } else {
921                         /* Lock is now held by client, or has been rejected.
922                          * In both cases, the block should be removed. */
923                         nlmsvc_unlink_block(block);
924                 }
925         }
926         nlmsvc_release_block(block);
927 }
928
929 /* Helper function to handle retry of a deferred block.
930  * If it is a blocking lock, call grant_blocked.
931  * For a non-blocking lock or test lock, revisit the request.
932  */
933 static void
934 retry_deferred_block(struct nlm_block *block)
935 {
936         if (!(block->b_flags & B_GOT_CALLBACK))
937                 block->b_flags |= B_TIMED_OUT;
938         nlmsvc_insert_block(block, NLM_TIMEOUT);
939         dprintk("revisit block %p flags %d\n",  block, block->b_flags);
940         if (block->b_deferred_req) {
941                 block->b_deferred_req->revisit(block->b_deferred_req, 0);
942                 block->b_deferred_req = NULL;
943         }
944 }
945
946 /*
947  * Retry all blocked locks that have been notified. This is where lockd
948  * picks up locks that can be granted, or grant notifications that must
949  * be retransmitted.
950  */
951 unsigned long
952 nlmsvc_retry_blocked(void)
953 {
954         unsigned long   timeout = MAX_SCHEDULE_TIMEOUT;
955         struct nlm_block *block;
956
957         spin_lock(&nlm_blocked_lock);
958         while (!list_empty(&nlm_blocked) && !kthread_should_stop()) {
959                 block = list_entry(nlm_blocked.next, struct nlm_block, b_list);
960
961                 if (block->b_when == NLM_NEVER)
962                         break;
963                 if (time_after(block->b_when, jiffies)) {
964                         timeout = block->b_when - jiffies;
965                         break;
966                 }
967                 spin_unlock(&nlm_blocked_lock);
968
969                 dprintk("nlmsvc_retry_blocked(%p, when=%ld)\n",
970                         block, block->b_when);
971                 if (block->b_flags & B_QUEUED) {
972                         dprintk("nlmsvc_retry_blocked delete block (%p, granted=%d, flags=%d)\n",
973                                 block, block->b_granted, block->b_flags);
974                         retry_deferred_block(block);
975                 } else
976                         nlmsvc_grant_blocked(block);
977                 spin_lock(&nlm_blocked_lock);
978         }
979         spin_unlock(&nlm_blocked_lock);
980
981         return timeout;
982 }