Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
[linux-drm-fsl-dcu.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_file->f_file, &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         mutex_lock(&file->f_mutex);
293         list_del_init(&block->b_flist);
294         mutex_unlock(&file->f_mutex);
295
296         nlmsvc_freegrantargs(block->b_call);
297         nlmsvc_release_call(block->b_call);
298         nlm_release_file(block->b_file);
299         kfree(block->b_fl);
300         kfree(block);
301 }
302
303 static void nlmsvc_release_block(struct nlm_block *block)
304 {
305         if (block != NULL)
306                 kref_put(&block->b_count, nlmsvc_free_block);
307 }
308
309 /*
310  * Loop over all blocks and delete blocks held by
311  * a matching host.
312  */
313 void nlmsvc_traverse_blocks(struct nlm_host *host,
314                         struct nlm_file *file,
315                         nlm_host_match_fn_t match)
316 {
317         struct nlm_block *block, *next;
318
319 restart:
320         mutex_lock(&file->f_mutex);
321         list_for_each_entry_safe(block, next, &file->f_blocks, b_flist) {
322                 if (!match(block->b_host, host))
323                         continue;
324                 /* Do not destroy blocks that are not on
325                  * the global retry list - why? */
326                 if (list_empty(&block->b_list))
327                         continue;
328                 kref_get(&block->b_count);
329                 mutex_unlock(&file->f_mutex);
330                 nlmsvc_unlink_block(block);
331                 nlmsvc_release_block(block);
332                 goto restart;
333         }
334         mutex_unlock(&file->f_mutex);
335 }
336
337 /*
338  * Initialize arguments for GRANTED call. The nlm_rqst structure
339  * has been cleared already.
340  */
341 static int nlmsvc_setgrantargs(struct nlm_rqst *call, struct nlm_lock *lock)
342 {
343         locks_copy_lock(&call->a_args.lock.fl, &lock->fl);
344         memcpy(&call->a_args.lock.fh, &lock->fh, sizeof(call->a_args.lock.fh));
345         call->a_args.lock.caller = utsname()->nodename;
346         call->a_args.lock.oh.len = lock->oh.len;
347
348         /* set default data area */
349         call->a_args.lock.oh.data = call->a_owner;
350         call->a_args.lock.svid = lock->fl.fl_pid;
351
352         if (lock->oh.len > NLMCLNT_OHSIZE) {
353                 void *data = kmalloc(lock->oh.len, GFP_KERNEL);
354                 if (!data)
355                         return 0;
356                 call->a_args.lock.oh.data = (u8 *) data;
357         }
358
359         memcpy(call->a_args.lock.oh.data, lock->oh.data, lock->oh.len);
360         return 1;
361 }
362
363 static void nlmsvc_freegrantargs(struct nlm_rqst *call)
364 {
365         if (call->a_args.lock.oh.data != call->a_owner)
366                 kfree(call->a_args.lock.oh.data);
367
368         locks_release_private(&call->a_args.lock.fl);
369 }
370
371 /*
372  * Deferred lock request handling for non-blocking lock
373  */
374 static __be32
375 nlmsvc_defer_lock_rqst(struct svc_rqst *rqstp, struct nlm_block *block)
376 {
377         __be32 status = nlm_lck_denied_nolocks;
378
379         block->b_flags |= B_QUEUED;
380
381         nlmsvc_insert_block(block, NLM_TIMEOUT);
382
383         block->b_cache_req = &rqstp->rq_chandle;
384         if (rqstp->rq_chandle.defer) {
385                 block->b_deferred_req =
386                         rqstp->rq_chandle.defer(block->b_cache_req);
387                 if (block->b_deferred_req != NULL)
388                         status = nlm_drop_reply;
389         }
390         dprintk("lockd: nlmsvc_defer_lock_rqst block %p flags %d status %d\n",
391                 block, block->b_flags, ntohl(status));
392
393         return status;
394 }
395
396 /*
397  * Attempt to establish a lock, and if it can't be granted, block it
398  * if required.
399  */
400 __be32
401 nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file,
402             struct nlm_host *host, struct nlm_lock *lock, int wait,
403             struct nlm_cookie *cookie, int reclaim)
404 {
405         struct nlm_block        *block = NULL;
406         int                     error;
407         __be32                  ret;
408
409         dprintk("lockd: nlmsvc_lock(%s/%ld, ty=%d, pi=%d, %Ld-%Ld, bl=%d)\n",
410                                 file->f_file->f_path.dentry->d_inode->i_sb->s_id,
411                                 file->f_file->f_path.dentry->d_inode->i_ino,
412                                 lock->fl.fl_type, lock->fl.fl_pid,
413                                 (long long)lock->fl.fl_start,
414                                 (long long)lock->fl.fl_end,
415                                 wait);
416
417         /* Lock file against concurrent access */
418         mutex_lock(&file->f_mutex);
419         /* Get existing block (in case client is busy-waiting)
420          * or create new block
421          */
422         block = nlmsvc_lookup_block(file, lock);
423         if (block == NULL) {
424                 block = nlmsvc_create_block(rqstp, host, file, lock, cookie);
425                 ret = nlm_lck_denied_nolocks;
426                 if (block == NULL)
427                         goto out;
428                 lock = &block->b_call->a_args.lock;
429         } else
430                 lock->fl.fl_flags &= ~FL_SLEEP;
431
432         if (block->b_flags & B_QUEUED) {
433                 dprintk("lockd: nlmsvc_lock deferred block %p flags %d\n",
434                                                         block, block->b_flags);
435                 if (block->b_granted) {
436                         nlmsvc_unlink_block(block);
437                         ret = nlm_granted;
438                         goto out;
439                 }
440                 if (block->b_flags & B_TIMED_OUT) {
441                         nlmsvc_unlink_block(block);
442                         ret = nlm_lck_denied;
443                         goto out;
444                 }
445                 ret = nlm_drop_reply;
446                 goto out;
447         }
448
449         if (locks_in_grace(SVC_NET(rqstp)) && !reclaim) {
450                 ret = nlm_lck_denied_grace_period;
451                 goto out;
452         }
453         if (reclaim && !locks_in_grace(SVC_NET(rqstp))) {
454                 ret = nlm_lck_denied_grace_period;
455                 goto out;
456         }
457
458         if (!wait)
459                 lock->fl.fl_flags &= ~FL_SLEEP;
460         error = vfs_lock_file(file->f_file, F_SETLK, &lock->fl, NULL);
461         lock->fl.fl_flags &= ~FL_SLEEP;
462
463         dprintk("lockd: vfs_lock_file returned %d\n", error);
464         switch (error) {
465                 case 0:
466                         ret = nlm_granted;
467                         goto out;
468                 case -EAGAIN:
469                         /*
470                          * If this is a blocking request for an
471                          * already pending lock request then we need
472                          * to put it back on lockd's block list
473                          */
474                         if (wait)
475                                 break;
476                         ret = nlm_lck_denied;
477                         goto out;
478                 case FILE_LOCK_DEFERRED:
479                         if (wait)
480                                 break;
481                         /* Filesystem lock operation is in progress
482                            Add it to the queue waiting for callback */
483                         ret = nlmsvc_defer_lock_rqst(rqstp, block);
484                         goto out;
485                 case -EDEADLK:
486                         ret = nlm_deadlock;
487                         goto out;
488                 default:                        /* includes ENOLCK */
489                         ret = nlm_lck_denied_nolocks;
490                         goto out;
491         }
492
493         ret = nlm_lck_blocked;
494
495         /* Append to list of blocked */
496         nlmsvc_insert_block(block, NLM_NEVER);
497 out:
498         mutex_unlock(&file->f_mutex);
499         nlmsvc_release_block(block);
500         dprintk("lockd: nlmsvc_lock returned %u\n", ret);
501         return ret;
502 }
503
504 /*
505  * Test for presence of a conflicting lock.
506  */
507 __be32
508 nlmsvc_testlock(struct svc_rqst *rqstp, struct nlm_file *file,
509                 struct nlm_host *host, struct nlm_lock *lock,
510                 struct nlm_lock *conflock, struct nlm_cookie *cookie)
511 {
512         struct nlm_block        *block = NULL;
513         int                     error;
514         __be32                  ret;
515
516         dprintk("lockd: nlmsvc_testlock(%s/%ld, ty=%d, %Ld-%Ld)\n",
517                                 file->f_file->f_path.dentry->d_inode->i_sb->s_id,
518                                 file->f_file->f_path.dentry->d_inode->i_ino,
519                                 lock->fl.fl_type,
520                                 (long long)lock->fl.fl_start,
521                                 (long long)lock->fl.fl_end);
522
523         /* Get existing block (in case client is busy-waiting) */
524         block = nlmsvc_lookup_block(file, lock);
525
526         if (block == NULL) {
527                 struct file_lock *conf = kzalloc(sizeof(*conf), GFP_KERNEL);
528
529                 if (conf == NULL)
530                         return nlm_granted;
531                 block = nlmsvc_create_block(rqstp, host, file, lock, cookie);
532                 if (block == NULL) {
533                         kfree(conf);
534                         return nlm_granted;
535                 }
536                 block->b_fl = conf;
537         }
538         if (block->b_flags & B_QUEUED) {
539                 dprintk("lockd: nlmsvc_testlock deferred block %p flags %d fl %p\n",
540                         block, block->b_flags, block->b_fl);
541                 if (block->b_flags & B_TIMED_OUT) {
542                         nlmsvc_unlink_block(block);
543                         ret = nlm_lck_denied;
544                         goto out;
545                 }
546                 if (block->b_flags & B_GOT_CALLBACK) {
547                         nlmsvc_unlink_block(block);
548                         if (block->b_fl != NULL
549                                         && block->b_fl->fl_type != F_UNLCK) {
550                                 lock->fl = *block->b_fl;
551                                 goto conf_lock;
552                         } else {
553                                 ret = nlm_granted;
554                                 goto out;
555                         }
556                 }
557                 ret = nlm_drop_reply;
558                 goto out;
559         }
560
561         if (locks_in_grace(SVC_NET(rqstp))) {
562                 ret = nlm_lck_denied_grace_period;
563                 goto out;
564         }
565         error = vfs_test_lock(file->f_file, &lock->fl);
566         if (error == FILE_LOCK_DEFERRED) {
567                 ret = nlmsvc_defer_lock_rqst(rqstp, block);
568                 goto out;
569         }
570         if (error) {
571                 ret = nlm_lck_denied_nolocks;
572                 goto out;
573         }
574         if (lock->fl.fl_type == F_UNLCK) {
575                 ret = nlm_granted;
576                 goto out;
577         }
578
579 conf_lock:
580         dprintk("lockd: conflicting lock(ty=%d, %Ld-%Ld)\n",
581                 lock->fl.fl_type, (long long)lock->fl.fl_start,
582                 (long long)lock->fl.fl_end);
583         conflock->caller = "somehost";  /* FIXME */
584         conflock->len = strlen(conflock->caller);
585         conflock->oh.len = 0;           /* don't return OH info */
586         conflock->svid = lock->fl.fl_pid;
587         conflock->fl.fl_type = lock->fl.fl_type;
588         conflock->fl.fl_start = lock->fl.fl_start;
589         conflock->fl.fl_end = lock->fl.fl_end;
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->f_file->f_path.dentry->d_inode->i_sb->s_id,
611                                 file->f_file->f_path.dentry->d_inode->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->f_file->f_path.dentry->d_inode->i_sb->s_id,
640                                 file->f_file->f_path.dentry->d_inode->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, struct file_lock *conf,
672                              int result)
673 {
674         block->b_flags |= B_GOT_CALLBACK;
675         if (result == 0)
676                 block->b_granted = 1;
677         else
678                 block->b_flags |= B_TIMED_OUT;
679         if (conf) {
680                 if (block->b_fl)
681                         __locks_copy_lock(block->b_fl, conf);
682         }
683 }
684
685 static int nlmsvc_grant_deferred(struct file_lock *fl, struct file_lock *conf,
686                                         int result)
687 {
688         struct nlm_block *block;
689         int rc = -ENOENT;
690
691         spin_lock(&nlm_blocked_lock);
692         list_for_each_entry(block, &nlm_blocked, b_list) {
693                 if (nlm_compare_locks(&block->b_call->a_args.lock.fl, fl)) {
694                         dprintk("lockd: nlmsvc_notify_blocked block %p flags %d\n",
695                                                         block, block->b_flags);
696                         if (block->b_flags & B_QUEUED) {
697                                 if (block->b_flags & B_TIMED_OUT) {
698                                         rc = -ENOLCK;
699                                         break;
700                                 }
701                                 nlmsvc_update_deferred_block(block, conf, result);
702                         } else if (result == 0)
703                                 block->b_granted = 1;
704
705                         nlmsvc_insert_block_locked(block, 0);
706                         svc_wake_up(block->b_daemon);
707                         rc = 0;
708                         break;
709                 }
710         }
711         spin_unlock(&nlm_blocked_lock);
712         if (rc == -ENOENT)
713                 printk(KERN_WARNING "lockd: grant for unknown block\n");
714         return rc;
715 }
716
717 /*
718  * Unblock a blocked lock request. This is a callback invoked from the
719  * VFS layer when a lock on which we blocked is removed.
720  *
721  * This function doesn't grant the blocked lock instantly, but rather moves
722  * the block to the head of nlm_blocked where it can be picked up by lockd.
723  */
724 static void
725 nlmsvc_notify_blocked(struct file_lock *fl)
726 {
727         struct nlm_block        *block;
728
729         dprintk("lockd: VFS unblock notification for block %p\n", fl);
730         spin_lock(&nlm_blocked_lock);
731         list_for_each_entry(block, &nlm_blocked, b_list) {
732                 if (nlm_compare_locks(&block->b_call->a_args.lock.fl, fl)) {
733                         nlmsvc_insert_block_locked(block, 0);
734                         spin_unlock(&nlm_blocked_lock);
735                         svc_wake_up(block->b_daemon);
736                         return;
737                 }
738         }
739         spin_unlock(&nlm_blocked_lock);
740         printk(KERN_WARNING "lockd: notification for unknown block!\n");
741 }
742
743 static int nlmsvc_same_owner(struct file_lock *fl1, struct file_lock *fl2)
744 {
745         return fl1->fl_owner == fl2->fl_owner && fl1->fl_pid == fl2->fl_pid;
746 }
747
748 const struct lock_manager_operations nlmsvc_lock_operations = {
749         .lm_compare_owner = nlmsvc_same_owner,
750         .lm_notify = nlmsvc_notify_blocked,
751         .lm_grant = nlmsvc_grant_deferred,
752 };
753
754 /*
755  * Try to claim a lock that was previously blocked.
756  *
757  * Note that we use both the RPC_GRANTED_MSG call _and_ an async
758  * RPC thread when notifying the client. This seems like overkill...
759  * Here's why:
760  *  -   we don't want to use a synchronous RPC thread, otherwise
761  *      we might find ourselves hanging on a dead portmapper.
762  *  -   Some lockd implementations (e.g. HP) don't react to
763  *      RPC_GRANTED calls; they seem to insist on RPC_GRANTED_MSG calls.
764  */
765 static void
766 nlmsvc_grant_blocked(struct nlm_block *block)
767 {
768         struct nlm_file         *file = block->b_file;
769         struct nlm_lock         *lock = &block->b_call->a_args.lock;
770         int                     error;
771
772         dprintk("lockd: grant blocked lock %p\n", block);
773
774         kref_get(&block->b_count);
775
776         /* Unlink block request from list */
777         nlmsvc_unlink_block(block);
778
779         /* If b_granted is true this means we've been here before.
780          * Just retry the grant callback, possibly refreshing the RPC
781          * binding */
782         if (block->b_granted) {
783                 nlm_rebind_host(block->b_host);
784                 goto callback;
785         }
786
787         /* Try the lock operation again */
788         lock->fl.fl_flags |= FL_SLEEP;
789         error = vfs_lock_file(file->f_file, F_SETLK, &lock->fl, NULL);
790         lock->fl.fl_flags &= ~FL_SLEEP;
791
792         switch (error) {
793         case 0:
794                 break;
795         case FILE_LOCK_DEFERRED:
796                 dprintk("lockd: lock still blocked error %d\n", error);
797                 nlmsvc_insert_block(block, NLM_NEVER);
798                 nlmsvc_release_block(block);
799                 return;
800         default:
801                 printk(KERN_WARNING "lockd: unexpected error %d in %s!\n",
802                                 -error, __func__);
803                 nlmsvc_insert_block(block, 10 * HZ);
804                 nlmsvc_release_block(block);
805                 return;
806         }
807
808 callback:
809         /* Lock was granted by VFS. */
810         dprintk("lockd: GRANTing blocked lock.\n");
811         block->b_granted = 1;
812
813         /* keep block on the list, but don't reattempt until the RPC
814          * completes or the submission fails
815          */
816         nlmsvc_insert_block(block, NLM_NEVER);
817
818         /* Call the client -- use a soft RPC task since nlmsvc_retry_blocked
819          * will queue up a new one if this one times out
820          */
821         error = nlm_async_call(block->b_call, NLMPROC_GRANTED_MSG,
822                                 &nlmsvc_grant_ops);
823
824         /* RPC submission failed, wait a bit and retry */
825         if (error < 0)
826                 nlmsvc_insert_block(block, 10 * HZ);
827 }
828
829 /*
830  * This is the callback from the RPC layer when the NLM_GRANTED_MSG
831  * RPC call has succeeded or timed out.
832  * Like all RPC callbacks, it is invoked by the rpciod process, so it
833  * better not sleep. Therefore, we put the blocked lock on the nlm_blocked
834  * chain once more in order to have it removed by lockd itself (which can
835  * then sleep on the file semaphore without disrupting e.g. the nfs client).
836  */
837 static void nlmsvc_grant_callback(struct rpc_task *task, void *data)
838 {
839         struct nlm_rqst         *call = data;
840         struct nlm_block        *block = call->a_block;
841         unsigned long           timeout;
842
843         dprintk("lockd: GRANT_MSG RPC callback\n");
844
845         spin_lock(&nlm_blocked_lock);
846         /* if the block is not on a list at this point then it has
847          * been invalidated. Don't try to requeue it.
848          *
849          * FIXME: it's possible that the block is removed from the list
850          * after this check but before the nlmsvc_insert_block. In that
851          * case it will be added back. Perhaps we need better locking
852          * for nlm_blocked?
853          */
854         if (list_empty(&block->b_list))
855                 goto out;
856
857         /* Technically, we should down the file semaphore here. Since we
858          * move the block towards the head of the queue only, no harm
859          * can be done, though. */
860         if (task->tk_status < 0) {
861                 /* RPC error: Re-insert for retransmission */
862                 timeout = 10 * HZ;
863         } else {
864                 /* Call was successful, now wait for client callback */
865                 timeout = 60 * HZ;
866         }
867         nlmsvc_insert_block_locked(block, timeout);
868         svc_wake_up(block->b_daemon);
869 out:
870         spin_unlock(&nlm_blocked_lock);
871 }
872
873 /*
874  * FIXME: nlmsvc_release_block() grabs a mutex.  This is not allowed for an
875  * .rpc_release rpc_call_op
876  */
877 static void nlmsvc_grant_release(void *data)
878 {
879         struct nlm_rqst         *call = data;
880         nlmsvc_release_block(call->a_block);
881 }
882
883 static const struct rpc_call_ops nlmsvc_grant_ops = {
884         .rpc_call_done = nlmsvc_grant_callback,
885         .rpc_release = nlmsvc_grant_release,
886 };
887
888 /*
889  * We received a GRANT_RES callback. Try to find the corresponding
890  * block.
891  */
892 void
893 nlmsvc_grant_reply(struct nlm_cookie *cookie, __be32 status)
894 {
895         struct nlm_block        *block;
896
897         dprintk("grant_reply: looking for cookie %x, s=%d \n",
898                 *(unsigned int *)(cookie->data), status);
899         if (!(block = nlmsvc_find_block(cookie)))
900                 return;
901
902         if (block) {
903                 if (status == nlm_lck_denied_grace_period) {
904                         /* Try again in a couple of seconds */
905                         nlmsvc_insert_block(block, 10 * HZ);
906                 } else {
907                         /* Lock is now held by client, or has been rejected.
908                          * In both cases, the block should be removed. */
909                         nlmsvc_unlink_block(block);
910                 }
911         }
912         nlmsvc_release_block(block);
913 }
914
915 /* Helper function to handle retry of a deferred block.
916  * If it is a blocking lock, call grant_blocked.
917  * For a non-blocking lock or test lock, revisit the request.
918  */
919 static void
920 retry_deferred_block(struct nlm_block *block)
921 {
922         if (!(block->b_flags & B_GOT_CALLBACK))
923                 block->b_flags |= B_TIMED_OUT;
924         nlmsvc_insert_block(block, NLM_TIMEOUT);
925         dprintk("revisit block %p flags %d\n",  block, block->b_flags);
926         if (block->b_deferred_req) {
927                 block->b_deferred_req->revisit(block->b_deferred_req, 0);
928                 block->b_deferred_req = NULL;
929         }
930 }
931
932 /*
933  * Retry all blocked locks that have been notified. This is where lockd
934  * picks up locks that can be granted, or grant notifications that must
935  * be retransmitted.
936  */
937 unsigned long
938 nlmsvc_retry_blocked(void)
939 {
940         unsigned long   timeout = MAX_SCHEDULE_TIMEOUT;
941         struct nlm_block *block;
942
943         while (!list_empty(&nlm_blocked) && !kthread_should_stop()) {
944                 block = list_entry(nlm_blocked.next, struct nlm_block, b_list);
945
946                 if (block->b_when == NLM_NEVER)
947                         break;
948                 if (time_after(block->b_when, jiffies)) {
949                         timeout = block->b_when - jiffies;
950                         break;
951                 }
952
953                 dprintk("nlmsvc_retry_blocked(%p, when=%ld)\n",
954                         block, block->b_when);
955                 if (block->b_flags & B_QUEUED) {
956                         dprintk("nlmsvc_retry_blocked delete block (%p, granted=%d, flags=%d)\n",
957                                 block, block->b_granted, block->b_flags);
958                         retry_deferred_block(block);
959                 } else
960                         nlmsvc_grant_blocked(block);
961         }
962
963         return timeout;
964 }