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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.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
42static void nlmsvc_release_block(struct nlm_block *block);
43static void nlmsvc_insert_block(struct nlm_block *block, unsigned long);
44static void nlmsvc_remove_block(struct nlm_block *block);
45
46static int nlmsvc_setgrantargs(struct nlm_rqst *call, struct nlm_lock *lock);
47static void nlmsvc_freegrantargs(struct nlm_rqst *call);
48static const struct rpc_call_ops nlmsvc_grant_ops;
49static const char *nlmdbg_cookie2a(const struct nlm_cookie *cookie);
50
51/*
52 * The list of blocked locks to retry
53 */
54static LIST_HEAD(nlm_blocked);
55static DEFINE_SPINLOCK(nlm_blocked_lock);
56
57/*
58 * Insert a blocked lock into the global list
59 */
60static void
61nlmsvc_insert_block_locked(struct nlm_block *block, unsigned long when)
62{
63 struct nlm_block *b;
64 struct list_head *pos;
65
66 dprintk("lockd: nlmsvc_insert_block(%p, %ld)\n", block, when);
67 if (list_empty(&block->b_list)) {
68 kref_get(&block->b_count);
69 } else {
70 list_del_init(&block->b_list);
71 }
72
73 pos = &nlm_blocked;
74 if (when != NLM_NEVER) {
75 if ((when += jiffies) == NLM_NEVER)
76 when ++;
77 list_for_each(pos, &nlm_blocked) {
78 b = list_entry(pos, struct nlm_block, b_list);
79 if (time_after(b->b_when,when) || b->b_when == NLM_NEVER)
80 break;
81 }
82 /* On normal exit from the loop, pos == &nlm_blocked,
83 * so we will be adding to the end of the list - good
84 */
85 }
86
87 list_add_tail(&block->b_list, pos);
88 block->b_when = when;
89}
90
91static void nlmsvc_insert_block(struct nlm_block *block, unsigned long when)
92{
93 spin_lock(&nlm_blocked_lock);
94 nlmsvc_insert_block_locked(block, when);
95 spin_unlock(&nlm_blocked_lock);
96}
97
98/*
99 * Remove a block from the global list
100 */
101static inline void
102nlmsvc_remove_block(struct nlm_block *block)
103{
104 if (!list_empty(&block->b_list)) {
105 spin_lock(&nlm_blocked_lock);
106 list_del_init(&block->b_list);
107 spin_unlock(&nlm_blocked_lock);
108 nlmsvc_release_block(block);
109 }
110}
111
112/*
113 * Find a block for a given lock
114 */
115static struct nlm_block *
116nlmsvc_lookup_block(struct nlm_file *file, struct nlm_lock *lock)
117{
118 struct nlm_block *block;
119 struct file_lock *fl;
120
121 dprintk("lockd: nlmsvc_lookup_block f=%p pd=%d %Ld-%Ld ty=%d\n",
122 file, lock->fl.fl_pid,
123 (long long)lock->fl.fl_start,
124 (long long)lock->fl.fl_end, lock->fl.fl_type);
125 list_for_each_entry(block, &nlm_blocked, b_list) {
126 fl = &block->b_call->a_args.lock.fl;
127 dprintk("lockd: check f=%p pd=%d %Ld-%Ld ty=%d cookie=%s\n",
128 block->b_file, fl->fl_pid,
129 (long long)fl->fl_start,
130 (long long)fl->fl_end, fl->fl_type,
131 nlmdbg_cookie2a(&block->b_call->a_args.cookie));
132 if (block->b_file == file && nlm_compare_locks(fl, &lock->fl)) {
133 kref_get(&block->b_count);
134 return block;
135 }
136 }
137
138 return NULL;
139}
140
141static inline int nlm_cookie_match(struct nlm_cookie *a, struct nlm_cookie *b)
142{
143 if (a->len != b->len)
144 return 0;
145 if (memcmp(a->data, b->data, a->len))
146 return 0;
147 return 1;
148}
149
150/*
151 * Find a block with a given NLM cookie.
152 */
153static inline struct nlm_block *
154nlmsvc_find_block(struct nlm_cookie *cookie)
155{
156 struct nlm_block *block;
157
158 list_for_each_entry(block, &nlm_blocked, b_list) {
159 if (nlm_cookie_match(&block->b_call->a_args.cookie,cookie))
160 goto found;
161 }
162
163 return NULL;
164
165found:
166 dprintk("nlmsvc_find_block(%s): block=%p\n", nlmdbg_cookie2a(cookie), block);
167 kref_get(&block->b_count);
168 return block;
169}
170
171/*
172 * Create a block and initialize it.
173 *
174 * Note: we explicitly set the cookie of the grant reply to that of
175 * the blocked lock request. The spec explicitly mentions that the client
176 * should _not_ rely on the callback containing the same cookie as the
177 * request, but (as I found out later) that's because some implementations
178 * do just this. Never mind the standards comittees, they support our
179 * logging industries.
180 *
181 * 10 years later: I hope we can safely ignore these old and broken
182 * clients by now. Let's fix this so we can uniquely identify an incoming
183 * GRANTED_RES message by cookie, without having to rely on the client's IP
184 * address. --okir
185 */
186static struct nlm_block *
187nlmsvc_create_block(struct svc_rqst *rqstp, struct nlm_host *host,
188 struct nlm_file *file, struct nlm_lock *lock,
189 struct nlm_cookie *cookie)
190{
191 struct nlm_block *block;
192 struct nlm_rqst *call = NULL;
193
194 nlm_get_host(host);
195 call = nlm_alloc_call(host);
196 if (call == NULL)
197 return NULL;
198
199 /* Allocate memory for block, and initialize arguments */
200 block = kzalloc(sizeof(*block), GFP_KERNEL);
201 if (block == NULL)
202 goto failed;
203 kref_init(&block->b_count);
204 INIT_LIST_HEAD(&block->b_list);
205 INIT_LIST_HEAD(&block->b_flist);
206
207 if (!nlmsvc_setgrantargs(call, lock))
208 goto failed_free;
209
210 /* Set notifier function for VFS, and init args */
211 call->a_args.lock.fl.fl_flags |= FL_SLEEP;
212 call->a_args.lock.fl.fl_lmops = &nlmsvc_lock_operations;
213 nlmclnt_next_cookie(&call->a_args.cookie);
214
215 dprintk("lockd: created block %p...\n", block);
216
217 /* Create and initialize the block */
218 block->b_daemon = rqstp->rq_server;
219 block->b_host = host;
220 block->b_file = file;
221 block->b_fl = NULL;
222 file->f_count++;
223
224 /* Add to file's list of blocks */
225 list_add(&block->b_flist, &file->f_blocks);
226
227 /* Set up RPC arguments for callback */
228 block->b_call = call;
229 call->a_flags = RPC_TASK_ASYNC;
230 call->a_block = block;
231
232 return block;
233
234failed_free:
235 kfree(block);
236failed:
237 nlmsvc_release_call(call);
238 return NULL;
239}
240
241/*
242 * Delete a block.
243 * It is the caller's responsibility to check whether the file
244 * can be closed hereafter.
245 */
246static int nlmsvc_unlink_block(struct nlm_block *block)
247{
248 int status;
249 dprintk("lockd: unlinking block %p...\n", block);
250
251 /* Remove block from list */
252 status = posix_unblock_lock(block->b_file->f_file, &block->b_call->a_args.lock.fl);
253 nlmsvc_remove_block(block);
254 return status;
255}
256
257static void nlmsvc_free_block(struct kref *kref)
258{
259 struct nlm_block *block = container_of(kref, struct nlm_block, b_count);
260 struct nlm_file *file = block->b_file;
261
262 dprintk("lockd: freeing block %p...\n", block);
263
264 /* Remove block from file's list of blocks */
265 mutex_lock(&file->f_mutex);
266 list_del_init(&block->b_flist);
267 mutex_unlock(&file->f_mutex);
268
269 nlmsvc_freegrantargs(block->b_call);
270 nlmsvc_release_call(block->b_call);
271 nlm_release_file(block->b_file);
272 kfree(block->b_fl);
273 kfree(block);
274}
275
276static void nlmsvc_release_block(struct nlm_block *block)
277{
278 if (block != NULL)
279 kref_put(&block->b_count, nlmsvc_free_block);
280}
281
282/*
283 * Loop over all blocks and delete blocks held by
284 * a matching host.
285 */
286void nlmsvc_traverse_blocks(struct nlm_host *host,
287 struct nlm_file *file,
288 nlm_host_match_fn_t match)
289{
290 struct nlm_block *block, *next;
291
292restart:
293 mutex_lock(&file->f_mutex);
294 list_for_each_entry_safe(block, next, &file->f_blocks, b_flist) {
295 if (!match(block->b_host, host))
296 continue;
297 /* Do not destroy blocks that are not on
298 * the global retry list - why? */
299 if (list_empty(&block->b_list))
300 continue;
301 kref_get(&block->b_count);
302 mutex_unlock(&file->f_mutex);
303 nlmsvc_unlink_block(block);
304 nlmsvc_release_block(block);
305 goto restart;
306 }
307 mutex_unlock(&file->f_mutex);
308}
309
310/*
311 * Initialize arguments for GRANTED call. The nlm_rqst structure
312 * has been cleared already.
313 */
314static int nlmsvc_setgrantargs(struct nlm_rqst *call, struct nlm_lock *lock)
315{
316 locks_copy_lock(&call->a_args.lock.fl, &lock->fl);
317 memcpy(&call->a_args.lock.fh, &lock->fh, sizeof(call->a_args.lock.fh));
318 call->a_args.lock.caller = utsname()->nodename;
319 call->a_args.lock.oh.len = lock->oh.len;
320
321 /* set default data area */
322 call->a_args.lock.oh.data = call->a_owner;
323 call->a_args.lock.svid = lock->fl.fl_pid;
324
325 if (lock->oh.len > NLMCLNT_OHSIZE) {
326 void *data = kmalloc(lock->oh.len, GFP_KERNEL);
327 if (!data)
328 return 0;
329 call->a_args.lock.oh.data = (u8 *) data;
330 }
331
332 memcpy(call->a_args.lock.oh.data, lock->oh.data, lock->oh.len);
333 return 1;
334}
335
336static void nlmsvc_freegrantargs(struct nlm_rqst *call)
337{
338 if (call->a_args.lock.oh.data != call->a_owner)
339 kfree(call->a_args.lock.oh.data);
340
341 locks_release_private(&call->a_args.lock.fl);
342}
343
344/*
345 * Deferred lock request handling for non-blocking lock
346 */
347static __be32
348nlmsvc_defer_lock_rqst(struct svc_rqst *rqstp, struct nlm_block *block)
349{
350 __be32 status = nlm_lck_denied_nolocks;
351
352 block->b_flags |= B_QUEUED;
353
354 nlmsvc_insert_block(block, NLM_TIMEOUT);
355
356 block->b_cache_req = &rqstp->rq_chandle;
357 if (rqstp->rq_chandle.defer) {
358 block->b_deferred_req =
359 rqstp->rq_chandle.defer(block->b_cache_req);
360 if (block->b_deferred_req != NULL)
361 status = nlm_drop_reply;
362 }
363 dprintk("lockd: nlmsvc_defer_lock_rqst block %p flags %d status %d\n",
364 block, block->b_flags, ntohl(status));
365
366 return status;
367}
368
369/*
370 * Attempt to establish a lock, and if it can't be granted, block it
371 * if required.
372 */
373__be32
374nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file,
375 struct nlm_host *host, struct nlm_lock *lock, int wait,
376 struct nlm_cookie *cookie, int reclaim)
377{
378 struct nlm_block *block = NULL;
379 int error;
380 __be32 ret;
381
382 dprintk("lockd: nlmsvc_lock(%s/%ld, ty=%d, pi=%d, %Ld-%Ld, bl=%d)\n",
383 file->f_file->f_path.dentry->d_inode->i_sb->s_id,
384 file->f_file->f_path.dentry->d_inode->i_ino,
385 lock->fl.fl_type, lock->fl.fl_pid,
386 (long long)lock->fl.fl_start,
387 (long long)lock->fl.fl_end,
388 wait);
389
390 /* Lock file against concurrent access */
391 mutex_lock(&file->f_mutex);
392 /* Get existing block (in case client is busy-waiting)
393 * or create new block
394 */
395 block = nlmsvc_lookup_block(file, lock);
396 if (block == NULL) {
397 block = nlmsvc_create_block(rqstp, host, file, lock, cookie);
398 ret = nlm_lck_denied_nolocks;
399 if (block == NULL)
400 goto out;
401 lock = &block->b_call->a_args.lock;
402 } else
403 lock->fl.fl_flags &= ~FL_SLEEP;
404
405 if (block->b_flags & B_QUEUED) {
406 dprintk("lockd: nlmsvc_lock deferred block %p flags %d\n",
407 block, block->b_flags);
408 if (block->b_granted) {
409 nlmsvc_unlink_block(block);
410 ret = nlm_granted;
411 goto out;
412 }
413 if (block->b_flags & B_TIMED_OUT) {
414 nlmsvc_unlink_block(block);
415 ret = nlm_lck_denied;
416 goto out;
417 }
418 ret = nlm_drop_reply;
419 goto out;
420 }
421
422 if (locks_in_grace() && !reclaim) {
423 ret = nlm_lck_denied_grace_period;
424 goto out;
425 }
426 if (reclaim && !locks_in_grace()) {
427 ret = nlm_lck_denied_grace_period;
428 goto out;
429 }
430
431 if (!wait)
432 lock->fl.fl_flags &= ~FL_SLEEP;
433 error = vfs_lock_file(file->f_file, F_SETLK, &lock->fl, NULL);
434 lock->fl.fl_flags &= ~FL_SLEEP;
435
436 dprintk("lockd: vfs_lock_file returned %d\n", error);
437 switch (error) {
438 case 0:
439 ret = nlm_granted;
440 goto out;
441 case -EAGAIN:
442 /*
443 * If this is a blocking request for an
444 * already pending lock request then we need
445 * to put it back on lockd's block list
446 */
447 if (wait)
448 break;
449 ret = nlm_lck_denied;
450 goto out;
451 case FILE_LOCK_DEFERRED:
452 if (wait)
453 break;
454 /* Filesystem lock operation is in progress
455 Add it to the queue waiting for callback */
456 ret = nlmsvc_defer_lock_rqst(rqstp, block);
457 goto out;
458 case -EDEADLK:
459 ret = nlm_deadlock;
460 goto out;
461 default: /* includes ENOLCK */
462 ret = nlm_lck_denied_nolocks;
463 goto out;
464 }
465
466 ret = nlm_lck_blocked;
467
468 /* Append to list of blocked */
469 nlmsvc_insert_block(block, NLM_NEVER);
470out:
471 mutex_unlock(&file->f_mutex);
472 nlmsvc_release_block(block);
473 dprintk("lockd: nlmsvc_lock returned %u\n", ret);
474 return ret;
475}
476
477/*
478 * Test for presence of a conflicting lock.
479 */
480__be32
481nlmsvc_testlock(struct svc_rqst *rqstp, struct nlm_file *file,
482 struct nlm_host *host, struct nlm_lock *lock,
483 struct nlm_lock *conflock, struct nlm_cookie *cookie)
484{
485 struct nlm_block *block = NULL;
486 int error;
487 __be32 ret;
488
489 dprintk("lockd: nlmsvc_testlock(%s/%ld, ty=%d, %Ld-%Ld)\n",
490 file->f_file->f_path.dentry->d_inode->i_sb->s_id,
491 file->f_file->f_path.dentry->d_inode->i_ino,
492 lock->fl.fl_type,
493 (long long)lock->fl.fl_start,
494 (long long)lock->fl.fl_end);
495
496 /* Get existing block (in case client is busy-waiting) */
497 block = nlmsvc_lookup_block(file, lock);
498
499 if (block == NULL) {
500 struct file_lock *conf = kzalloc(sizeof(*conf), GFP_KERNEL);
501
502 if (conf == NULL)
503 return nlm_granted;
504 block = nlmsvc_create_block(rqstp, host, file, lock, cookie);
505 if (block == NULL) {
506 kfree(conf);
507 return nlm_granted;
508 }
509 block->b_fl = conf;
510 }
511 if (block->b_flags & B_QUEUED) {
512 dprintk("lockd: nlmsvc_testlock deferred block %p flags %d fl %p\n",
513 block, block->b_flags, block->b_fl);
514 if (block->b_flags & B_TIMED_OUT) {
515 nlmsvc_unlink_block(block);
516 ret = nlm_lck_denied;
517 goto out;
518 }
519 if (block->b_flags & B_GOT_CALLBACK) {
520 nlmsvc_unlink_block(block);
521 if (block->b_fl != NULL
522 && block->b_fl->fl_type != F_UNLCK) {
523 lock->fl = *block->b_fl;
524 goto conf_lock;
525 } else {
526 ret = nlm_granted;
527 goto out;
528 }
529 }
530 ret = nlm_drop_reply;
531 goto out;
532 }
533
534 if (locks_in_grace()) {
535 ret = nlm_lck_denied_grace_period;
536 goto out;
537 }
538 error = vfs_test_lock(file->f_file, &lock->fl);
539 if (error == FILE_LOCK_DEFERRED) {
540 ret = nlmsvc_defer_lock_rqst(rqstp, block);
541 goto out;
542 }
543 if (error) {
544 ret = nlm_lck_denied_nolocks;
545 goto out;
546 }
547 if (lock->fl.fl_type == F_UNLCK) {
548 ret = nlm_granted;
549 goto out;
550 }
551
552conf_lock:
553 dprintk("lockd: conflicting lock(ty=%d, %Ld-%Ld)\n",
554 lock->fl.fl_type, (long long)lock->fl.fl_start,
555 (long long)lock->fl.fl_end);
556 conflock->caller = "somehost"; /* FIXME */
557 conflock->len = strlen(conflock->caller);
558 conflock->oh.len = 0; /* don't return OH info */
559 conflock->svid = lock->fl.fl_pid;
560 conflock->fl.fl_type = lock->fl.fl_type;
561 conflock->fl.fl_start = lock->fl.fl_start;
562 conflock->fl.fl_end = lock->fl.fl_end;
563 ret = nlm_lck_denied;
564out:
565 if (block)
566 nlmsvc_release_block(block);
567 return ret;
568}
569
570/*
571 * Remove a lock.
572 * This implies a CANCEL call: We send a GRANT_MSG, the client replies
573 * with a GRANT_RES call which gets lost, and calls UNLOCK immediately
574 * afterwards. In this case the block will still be there, and hence
575 * must be removed.
576 */
577__be32
578nlmsvc_unlock(struct nlm_file *file, struct nlm_lock *lock)
579{
580 int error;
581
582 dprintk("lockd: nlmsvc_unlock(%s/%ld, pi=%d, %Ld-%Ld)\n",
583 file->f_file->f_path.dentry->d_inode->i_sb->s_id,
584 file->f_file->f_path.dentry->d_inode->i_ino,
585 lock->fl.fl_pid,
586 (long long)lock->fl.fl_start,
587 (long long)lock->fl.fl_end);
588
589 /* First, cancel any lock that might be there */
590 nlmsvc_cancel_blocked(file, lock);
591
592 lock->fl.fl_type = F_UNLCK;
593 error = vfs_lock_file(file->f_file, F_SETLK, &lock->fl, NULL);
594
595 return (error < 0)? nlm_lck_denied_nolocks : nlm_granted;
596}
597
598/*
599 * Cancel a previously blocked request.
600 *
601 * A cancel request always overrides any grant that may currently
602 * be in progress.
603 * The calling procedure must check whether the file can be closed.
604 */
605__be32
606nlmsvc_cancel_blocked(struct nlm_file *file, struct nlm_lock *lock)
607{
608 struct nlm_block *block;
609 int status = 0;
610
611 dprintk("lockd: nlmsvc_cancel(%s/%ld, pi=%d, %Ld-%Ld)\n",
612 file->f_file->f_path.dentry->d_inode->i_sb->s_id,
613 file->f_file->f_path.dentry->d_inode->i_ino,
614 lock->fl.fl_pid,
615 (long long)lock->fl.fl_start,
616 (long long)lock->fl.fl_end);
617
618 if (locks_in_grace())
619 return nlm_lck_denied_grace_period;
620
621 mutex_lock(&file->f_mutex);
622 block = nlmsvc_lookup_block(file, lock);
623 mutex_unlock(&file->f_mutex);
624 if (block != NULL) {
625 vfs_cancel_lock(block->b_file->f_file,
626 &block->b_call->a_args.lock.fl);
627 status = nlmsvc_unlink_block(block);
628 nlmsvc_release_block(block);
629 }
630 return status ? nlm_lck_denied : nlm_granted;
631}
632
633/*
634 * This is a callback from the filesystem for VFS file lock requests.
635 * It will be used if lm_grant is defined and the filesystem can not
636 * respond to the request immediately.
637 * For GETLK request it will copy the reply to the nlm_block.
638 * For SETLK or SETLKW request it will get the local posix lock.
639 * In all cases it will move the block to the head of nlm_blocked q where
640 * nlmsvc_retry_blocked() can send back a reply for SETLKW or revisit the
641 * deferred rpc for GETLK and SETLK.
642 */
643static void
644nlmsvc_update_deferred_block(struct nlm_block *block, struct file_lock *conf,
645 int result)
646{
647 block->b_flags |= B_GOT_CALLBACK;
648 if (result == 0)
649 block->b_granted = 1;
650 else
651 block->b_flags |= B_TIMED_OUT;
652 if (conf) {
653 if (block->b_fl)
654 __locks_copy_lock(block->b_fl, conf);
655 }
656}
657
658static int nlmsvc_grant_deferred(struct file_lock *fl, struct file_lock *conf,
659 int result)
660{
661 struct nlm_block *block;
662 int rc = -ENOENT;
663
664 spin_lock(&nlm_blocked_lock);
665 list_for_each_entry(block, &nlm_blocked, b_list) {
666 if (nlm_compare_locks(&block->b_call->a_args.lock.fl, fl)) {
667 dprintk("lockd: nlmsvc_notify_blocked block %p flags %d\n",
668 block, block->b_flags);
669 if (block->b_flags & B_QUEUED) {
670 if (block->b_flags & B_TIMED_OUT) {
671 rc = -ENOLCK;
672 break;
673 }
674 nlmsvc_update_deferred_block(block, conf, result);
675 } else if (result == 0)
676 block->b_granted = 1;
677
678 nlmsvc_insert_block_locked(block, 0);
679 svc_wake_up(block->b_daemon);
680 rc = 0;
681 break;
682 }
683 }
684 spin_unlock(&nlm_blocked_lock);
685 if (rc == -ENOENT)
686 printk(KERN_WARNING "lockd: grant for unknown block\n");
687 return rc;
688}
689
690/*
691 * Unblock a blocked lock request. This is a callback invoked from the
692 * VFS layer when a lock on which we blocked is removed.
693 *
694 * This function doesn't grant the blocked lock instantly, but rather moves
695 * the block to the head of nlm_blocked where it can be picked up by lockd.
696 */
697static void
698nlmsvc_notify_blocked(struct file_lock *fl)
699{
700 struct nlm_block *block;
701
702 dprintk("lockd: VFS unblock notification for block %p\n", fl);
703 spin_lock(&nlm_blocked_lock);
704 list_for_each_entry(block, &nlm_blocked, b_list) {
705 if (nlm_compare_locks(&block->b_call->a_args.lock.fl, fl)) {
706 nlmsvc_insert_block_locked(block, 0);
707 spin_unlock(&nlm_blocked_lock);
708 svc_wake_up(block->b_daemon);
709 return;
710 }
711 }
712 spin_unlock(&nlm_blocked_lock);
713 printk(KERN_WARNING "lockd: notification for unknown block!\n");
714}
715
716static int nlmsvc_same_owner(struct file_lock *fl1, struct file_lock *fl2)
717{
718 return fl1->fl_owner == fl2->fl_owner && fl1->fl_pid == fl2->fl_pid;
719}
720
721const struct lock_manager_operations nlmsvc_lock_operations = {
722 .lm_compare_owner = nlmsvc_same_owner,
723 .lm_notify = nlmsvc_notify_blocked,
724 .lm_grant = nlmsvc_grant_deferred,
725};
726
727/*
728 * Try to claim a lock that was previously blocked.
729 *
730 * Note that we use both the RPC_GRANTED_MSG call _and_ an async
731 * RPC thread when notifying the client. This seems like overkill...
732 * Here's why:
733 * - we don't want to use a synchronous RPC thread, otherwise
734 * we might find ourselves hanging on a dead portmapper.
735 * - Some lockd implementations (e.g. HP) don't react to
736 * RPC_GRANTED calls; they seem to insist on RPC_GRANTED_MSG calls.
737 */
738static void
739nlmsvc_grant_blocked(struct nlm_block *block)
740{
741 struct nlm_file *file = block->b_file;
742 struct nlm_lock *lock = &block->b_call->a_args.lock;
743 int error;
744
745 dprintk("lockd: grant blocked lock %p\n", block);
746
747 kref_get(&block->b_count);
748
749 /* Unlink block request from list */
750 nlmsvc_unlink_block(block);
751
752 /* If b_granted is true this means we've been here before.
753 * Just retry the grant callback, possibly refreshing the RPC
754 * binding */
755 if (block->b_granted) {
756 nlm_rebind_host(block->b_host);
757 goto callback;
758 }
759
760 /* Try the lock operation again */
761 lock->fl.fl_flags |= FL_SLEEP;
762 error = vfs_lock_file(file->f_file, F_SETLK, &lock->fl, NULL);
763 lock->fl.fl_flags &= ~FL_SLEEP;
764
765 switch (error) {
766 case 0:
767 break;
768 case FILE_LOCK_DEFERRED:
769 dprintk("lockd: lock still blocked error %d\n", error);
770 nlmsvc_insert_block(block, NLM_NEVER);
771 nlmsvc_release_block(block);
772 return;
773 default:
774 printk(KERN_WARNING "lockd: unexpected error %d in %s!\n",
775 -error, __func__);
776 nlmsvc_insert_block(block, 10 * HZ);
777 nlmsvc_release_block(block);
778 return;
779 }
780
781callback:
782 /* Lock was granted by VFS. */
783 dprintk("lockd: GRANTing blocked lock.\n");
784 block->b_granted = 1;
785
786 /* keep block on the list, but don't reattempt until the RPC
787 * completes or the submission fails
788 */
789 nlmsvc_insert_block(block, NLM_NEVER);
790
791 /* Call the client -- use a soft RPC task since nlmsvc_retry_blocked
792 * will queue up a new one if this one times out
793 */
794 error = nlm_async_call(block->b_call, NLMPROC_GRANTED_MSG,
795 &nlmsvc_grant_ops);
796
797 /* RPC submission failed, wait a bit and retry */
798 if (error < 0)
799 nlmsvc_insert_block(block, 10 * HZ);
800}
801
802/*
803 * This is the callback from the RPC layer when the NLM_GRANTED_MSG
804 * RPC call has succeeded or timed out.
805 * Like all RPC callbacks, it is invoked by the rpciod process, so it
806 * better not sleep. Therefore, we put the blocked lock on the nlm_blocked
807 * chain once more in order to have it removed by lockd itself (which can
808 * then sleep on the file semaphore without disrupting e.g. the nfs client).
809 */
810static void nlmsvc_grant_callback(struct rpc_task *task, void *data)
811{
812 struct nlm_rqst *call = data;
813 struct nlm_block *block = call->a_block;
814 unsigned long timeout;
815
816 dprintk("lockd: GRANT_MSG RPC callback\n");
817
818 spin_lock(&nlm_blocked_lock);
819 /* if the block is not on a list at this point then it has
820 * been invalidated. Don't try to requeue it.
821 *
822 * FIXME: it's possible that the block is removed from the list
823 * after this check but before the nlmsvc_insert_block. In that
824 * case it will be added back. Perhaps we need better locking
825 * for nlm_blocked?
826 */
827 if (list_empty(&block->b_list))
828 goto out;
829
830 /* Technically, we should down the file semaphore here. Since we
831 * move the block towards the head of the queue only, no harm
832 * can be done, though. */
833 if (task->tk_status < 0) {
834 /* RPC error: Re-insert for retransmission */
835 timeout = 10 * HZ;
836 } else {
837 /* Call was successful, now wait for client callback */
838 timeout = 60 * HZ;
839 }
840 nlmsvc_insert_block_locked(block, timeout);
841 svc_wake_up(block->b_daemon);
842out:
843 spin_unlock(&nlm_blocked_lock);
844}
845
846/*
847 * FIXME: nlmsvc_release_block() grabs a mutex. This is not allowed for an
848 * .rpc_release rpc_call_op
849 */
850static void nlmsvc_grant_release(void *data)
851{
852 struct nlm_rqst *call = data;
853 nlmsvc_release_block(call->a_block);
854}
855
856static const struct rpc_call_ops nlmsvc_grant_ops = {
857 .rpc_call_done = nlmsvc_grant_callback,
858 .rpc_release = nlmsvc_grant_release,
859};
860
861/*
862 * We received a GRANT_RES callback. Try to find the corresponding
863 * block.
864 */
865void
866nlmsvc_grant_reply(struct nlm_cookie *cookie, __be32 status)
867{
868 struct nlm_block *block;
869
870 dprintk("grant_reply: looking for cookie %x, s=%d \n",
871 *(unsigned int *)(cookie->data), status);
872 if (!(block = nlmsvc_find_block(cookie)))
873 return;
874
875 if (block) {
876 if (status == nlm_lck_denied_grace_period) {
877 /* Try again in a couple of seconds */
878 nlmsvc_insert_block(block, 10 * HZ);
879 } else {
880 /* Lock is now held by client, or has been rejected.
881 * In both cases, the block should be removed. */
882 nlmsvc_unlink_block(block);
883 }
884 }
885 nlmsvc_release_block(block);
886}
887
888/* Helper function to handle retry of a deferred block.
889 * If it is a blocking lock, call grant_blocked.
890 * For a non-blocking lock or test lock, revisit the request.
891 */
892static void
893retry_deferred_block(struct nlm_block *block)
894{
895 if (!(block->b_flags & B_GOT_CALLBACK))
896 block->b_flags |= B_TIMED_OUT;
897 nlmsvc_insert_block(block, NLM_TIMEOUT);
898 dprintk("revisit block %p flags %d\n", block, block->b_flags);
899 if (block->b_deferred_req) {
900 block->b_deferred_req->revisit(block->b_deferred_req, 0);
901 block->b_deferred_req = NULL;
902 }
903}
904
905/*
906 * Retry all blocked locks that have been notified. This is where lockd
907 * picks up locks that can be granted, or grant notifications that must
908 * be retransmitted.
909 */
910unsigned long
911nlmsvc_retry_blocked(void)
912{
913 unsigned long timeout = MAX_SCHEDULE_TIMEOUT;
914 struct nlm_block *block;
915
916 while (!list_empty(&nlm_blocked) && !kthread_should_stop()) {
917 block = list_entry(nlm_blocked.next, struct nlm_block, b_list);
918
919 if (block->b_when == NLM_NEVER)
920 break;
921 if (time_after(block->b_when, jiffies)) {
922 timeout = block->b_when - jiffies;
923 break;
924 }
925
926 dprintk("nlmsvc_retry_blocked(%p, when=%ld)\n",
927 block, block->b_when);
928 if (block->b_flags & B_QUEUED) {
929 dprintk("nlmsvc_retry_blocked delete block (%p, granted=%d, flags=%d)\n",
930 block, block->b_granted, block->b_flags);
931 retry_deferred_block(block);
932 } else
933 nlmsvc_grant_blocked(block);
934 }
935
936 return timeout;
937}
938
939#ifdef RPC_DEBUG
940static const char *nlmdbg_cookie2a(const struct nlm_cookie *cookie)
941{
942 /*
943 * We can get away with a static buffer because we're only
944 * called with BKL held.
945 */
946 static char buf[2*NLM_MAXCOOKIELEN+1];
947 unsigned int i, len = sizeof(buf);
948 char *p = buf;
949
950 len--; /* allow for trailing \0 */
951 if (len < 3)
952 return "???";
953 for (i = 0 ; i < cookie->len ; i++) {
954 if (len < 2) {
955 strcpy(p-3, "...");
956 break;
957 }
958 sprintf(p, "%02x", cookie->data[i]);
959 p += 2;
960 len -= 2;
961 }
962 *p = '\0';
963
964 return buf;
965}
966#endif
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
42static void nlmsvc_release_block(struct nlm_block *block);
43static void nlmsvc_insert_block(struct nlm_block *block, unsigned long);
44static void nlmsvc_remove_block(struct nlm_block *block);
45
46static int nlmsvc_setgrantargs(struct nlm_rqst *call, struct nlm_lock *lock);
47static void nlmsvc_freegrantargs(struct nlm_rqst *call);
48static const struct rpc_call_ops nlmsvc_grant_ops;
49
50/*
51 * The list of blocked locks to retry
52 */
53static LIST_HEAD(nlm_blocked);
54static DEFINE_SPINLOCK(nlm_blocked_lock);
55
56#ifdef LOCKD_DEBUG
57static 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 */
88static void
89nlmsvc_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
119static 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 */
129static inline void
130nlmsvc_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 */
143static struct nlm_block *
144nlmsvc_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
169static 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 */
181static inline struct nlm_block *
182nlmsvc_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
193found:
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 */
214static struct nlm_block *
215nlmsvc_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
261failed_free:
262 kfree(block);
263failed:
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 */
273static 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
284static 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
302static 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 */
312void 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
318restart:
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 */
340static 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
362static 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 */
373static __be32
374nlmsvc_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
400nlmsvc_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);
496out:
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
507nlmsvc_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
578conf_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 ret = nlm_lck_denied;
590out:
591 if (block)
592 nlmsvc_release_block(block);
593 return ret;
594}
595
596/*
597 * Remove a lock.
598 * This implies a CANCEL call: We send a GRANT_MSG, the client replies
599 * with a GRANT_RES call which gets lost, and calls UNLOCK immediately
600 * afterwards. In this case the block will still be there, and hence
601 * must be removed.
602 */
603__be32
604nlmsvc_unlock(struct net *net, struct nlm_file *file, struct nlm_lock *lock)
605{
606 int error;
607
608 dprintk("lockd: nlmsvc_unlock(%s/%ld, pi=%d, %Ld-%Ld)\n",
609 file_inode(file->f_file)->i_sb->s_id,
610 file_inode(file->f_file)->i_ino,
611 lock->fl.fl_pid,
612 (long long)lock->fl.fl_start,
613 (long long)lock->fl.fl_end);
614
615 /* First, cancel any lock that might be there */
616 nlmsvc_cancel_blocked(net, file, lock);
617
618 lock->fl.fl_type = F_UNLCK;
619 error = vfs_lock_file(file->f_file, F_SETLK, &lock->fl, NULL);
620
621 return (error < 0)? nlm_lck_denied_nolocks : nlm_granted;
622}
623
624/*
625 * Cancel a previously blocked request.
626 *
627 * A cancel request always overrides any grant that may currently
628 * be in progress.
629 * The calling procedure must check whether the file can be closed.
630 */
631__be32
632nlmsvc_cancel_blocked(struct net *net, struct nlm_file *file, struct nlm_lock *lock)
633{
634 struct nlm_block *block;
635 int status = 0;
636
637 dprintk("lockd: nlmsvc_cancel(%s/%ld, pi=%d, %Ld-%Ld)\n",
638 file_inode(file->f_file)->i_sb->s_id,
639 file_inode(file->f_file)->i_ino,
640 lock->fl.fl_pid,
641 (long long)lock->fl.fl_start,
642 (long long)lock->fl.fl_end);
643
644 if (locks_in_grace(net))
645 return nlm_lck_denied_grace_period;
646
647 mutex_lock(&file->f_mutex);
648 block = nlmsvc_lookup_block(file, lock);
649 mutex_unlock(&file->f_mutex);
650 if (block != NULL) {
651 vfs_cancel_lock(block->b_file->f_file,
652 &block->b_call->a_args.lock.fl);
653 status = nlmsvc_unlink_block(block);
654 nlmsvc_release_block(block);
655 }
656 return status ? nlm_lck_denied : nlm_granted;
657}
658
659/*
660 * This is a callback from the filesystem for VFS file lock requests.
661 * It will be used if lm_grant is defined and the filesystem can not
662 * respond to the request immediately.
663 * For GETLK request it will copy the reply to the nlm_block.
664 * For SETLK or SETLKW request it will get the local posix lock.
665 * In all cases it will move the block to the head of nlm_blocked q where
666 * nlmsvc_retry_blocked() can send back a reply for SETLKW or revisit the
667 * deferred rpc for GETLK and SETLK.
668 */
669static void
670nlmsvc_update_deferred_block(struct nlm_block *block, struct file_lock *conf,
671 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 if (conf) {
679 if (block->b_fl)
680 __locks_copy_lock(block->b_fl, conf);
681 }
682}
683
684static int nlmsvc_grant_deferred(struct file_lock *fl, struct file_lock *conf,
685 int result)
686{
687 struct nlm_block *block;
688 int rc = -ENOENT;
689
690 spin_lock(&nlm_blocked_lock);
691 list_for_each_entry(block, &nlm_blocked, b_list) {
692 if (nlm_compare_locks(&block->b_call->a_args.lock.fl, fl)) {
693 dprintk("lockd: nlmsvc_notify_blocked block %p flags %d\n",
694 block, block->b_flags);
695 if (block->b_flags & B_QUEUED) {
696 if (block->b_flags & B_TIMED_OUT) {
697 rc = -ENOLCK;
698 break;
699 }
700 nlmsvc_update_deferred_block(block, conf, result);
701 } else if (result == 0)
702 block->b_granted = 1;
703
704 nlmsvc_insert_block_locked(block, 0);
705 svc_wake_up(block->b_daemon);
706 rc = 0;
707 break;
708 }
709 }
710 spin_unlock(&nlm_blocked_lock);
711 if (rc == -ENOENT)
712 printk(KERN_WARNING "lockd: grant for unknown block\n");
713 return rc;
714}
715
716/*
717 * Unblock a blocked lock request. This is a callback invoked from the
718 * VFS layer when a lock on which we blocked is removed.
719 *
720 * This function doesn't grant the blocked lock instantly, but rather moves
721 * the block to the head of nlm_blocked where it can be picked up by lockd.
722 */
723static void
724nlmsvc_notify_blocked(struct file_lock *fl)
725{
726 struct nlm_block *block;
727
728 dprintk("lockd: VFS unblock notification for block %p\n", fl);
729 spin_lock(&nlm_blocked_lock);
730 list_for_each_entry(block, &nlm_blocked, b_list) {
731 if (nlm_compare_locks(&block->b_call->a_args.lock.fl, fl)) {
732 nlmsvc_insert_block_locked(block, 0);
733 spin_unlock(&nlm_blocked_lock);
734 svc_wake_up(block->b_daemon);
735 return;
736 }
737 }
738 spin_unlock(&nlm_blocked_lock);
739 printk(KERN_WARNING "lockd: notification for unknown block!\n");
740}
741
742static int nlmsvc_same_owner(struct file_lock *fl1, struct file_lock *fl2)
743{
744 return fl1->fl_owner == fl2->fl_owner && fl1->fl_pid == fl2->fl_pid;
745}
746
747/*
748 * Since NLM uses two "keys" for tracking locks, we need to hash them down
749 * to one for the blocked_hash. Here, we're just xor'ing the host address
750 * with the pid in order to create a key value for picking a hash bucket.
751 */
752static unsigned long
753nlmsvc_owner_key(struct file_lock *fl)
754{
755 return (unsigned long)fl->fl_owner ^ (unsigned long)fl->fl_pid;
756}
757
758const struct lock_manager_operations nlmsvc_lock_operations = {
759 .lm_compare_owner = nlmsvc_same_owner,
760 .lm_owner_key = nlmsvc_owner_key,
761 .lm_notify = nlmsvc_notify_blocked,
762 .lm_grant = nlmsvc_grant_deferred,
763};
764
765/*
766 * Try to claim a lock that was previously blocked.
767 *
768 * Note that we use both the RPC_GRANTED_MSG call _and_ an async
769 * RPC thread when notifying the client. This seems like overkill...
770 * Here's why:
771 * - we don't want to use a synchronous RPC thread, otherwise
772 * we might find ourselves hanging on a dead portmapper.
773 * - Some lockd implementations (e.g. HP) don't react to
774 * RPC_GRANTED calls; they seem to insist on RPC_GRANTED_MSG calls.
775 */
776static void
777nlmsvc_grant_blocked(struct nlm_block *block)
778{
779 struct nlm_file *file = block->b_file;
780 struct nlm_lock *lock = &block->b_call->a_args.lock;
781 int error;
782 loff_t fl_start, fl_end;
783
784 dprintk("lockd: grant blocked lock %p\n", block);
785
786 kref_get(&block->b_count);
787
788 /* Unlink block request from list */
789 nlmsvc_unlink_block(block);
790
791 /* If b_granted is true this means we've been here before.
792 * Just retry the grant callback, possibly refreshing the RPC
793 * binding */
794 if (block->b_granted) {
795 nlm_rebind_host(block->b_host);
796 goto callback;
797 }
798
799 /* Try the lock operation again */
800 /* vfs_lock_file() can mangle fl_start and fl_end, but we need
801 * them unchanged for the GRANT_MSG
802 */
803 lock->fl.fl_flags |= FL_SLEEP;
804 fl_start = lock->fl.fl_start;
805 fl_end = lock->fl.fl_end;
806 error = vfs_lock_file(file->f_file, F_SETLK, &lock->fl, NULL);
807 lock->fl.fl_flags &= ~FL_SLEEP;
808 lock->fl.fl_start = fl_start;
809 lock->fl.fl_end = fl_end;
810
811 switch (error) {
812 case 0:
813 break;
814 case FILE_LOCK_DEFERRED:
815 dprintk("lockd: lock still blocked error %d\n", error);
816 nlmsvc_insert_block(block, NLM_NEVER);
817 nlmsvc_release_block(block);
818 return;
819 default:
820 printk(KERN_WARNING "lockd: unexpected error %d in %s!\n",
821 -error, __func__);
822 nlmsvc_insert_block(block, 10 * HZ);
823 nlmsvc_release_block(block);
824 return;
825 }
826
827callback:
828 /* Lock was granted by VFS. */
829 dprintk("lockd: GRANTing blocked lock.\n");
830 block->b_granted = 1;
831
832 /* keep block on the list, but don't reattempt until the RPC
833 * completes or the submission fails
834 */
835 nlmsvc_insert_block(block, NLM_NEVER);
836
837 /* Call the client -- use a soft RPC task since nlmsvc_retry_blocked
838 * will queue up a new one if this one times out
839 */
840 error = nlm_async_call(block->b_call, NLMPROC_GRANTED_MSG,
841 &nlmsvc_grant_ops);
842
843 /* RPC submission failed, wait a bit and retry */
844 if (error < 0)
845 nlmsvc_insert_block(block, 10 * HZ);
846}
847
848/*
849 * This is the callback from the RPC layer when the NLM_GRANTED_MSG
850 * RPC call has succeeded or timed out.
851 * Like all RPC callbacks, it is invoked by the rpciod process, so it
852 * better not sleep. Therefore, we put the blocked lock on the nlm_blocked
853 * chain once more in order to have it removed by lockd itself (which can
854 * then sleep on the file semaphore without disrupting e.g. the nfs client).
855 */
856static void nlmsvc_grant_callback(struct rpc_task *task, void *data)
857{
858 struct nlm_rqst *call = data;
859 struct nlm_block *block = call->a_block;
860 unsigned long timeout;
861
862 dprintk("lockd: GRANT_MSG RPC callback\n");
863
864 spin_lock(&nlm_blocked_lock);
865 /* if the block is not on a list at this point then it has
866 * been invalidated. Don't try to requeue it.
867 *
868 * FIXME: it's possible that the block is removed from the list
869 * after this check but before the nlmsvc_insert_block. In that
870 * case it will be added back. Perhaps we need better locking
871 * for nlm_blocked?
872 */
873 if (list_empty(&block->b_list))
874 goto out;
875
876 /* Technically, we should down the file semaphore here. Since we
877 * move the block towards the head of the queue only, no harm
878 * can be done, though. */
879 if (task->tk_status < 0) {
880 /* RPC error: Re-insert for retransmission */
881 timeout = 10 * HZ;
882 } else {
883 /* Call was successful, now wait for client callback */
884 timeout = 60 * HZ;
885 }
886 nlmsvc_insert_block_locked(block, timeout);
887 svc_wake_up(block->b_daemon);
888out:
889 spin_unlock(&nlm_blocked_lock);
890}
891
892/*
893 * FIXME: nlmsvc_release_block() grabs a mutex. This is not allowed for an
894 * .rpc_release rpc_call_op
895 */
896static void nlmsvc_grant_release(void *data)
897{
898 struct nlm_rqst *call = data;
899 nlmsvc_release_block(call->a_block);
900}
901
902static const struct rpc_call_ops nlmsvc_grant_ops = {
903 .rpc_call_done = nlmsvc_grant_callback,
904 .rpc_release = nlmsvc_grant_release,
905};
906
907/*
908 * We received a GRANT_RES callback. Try to find the corresponding
909 * block.
910 */
911void
912nlmsvc_grant_reply(struct nlm_cookie *cookie, __be32 status)
913{
914 struct nlm_block *block;
915
916 dprintk("grant_reply: looking for cookie %x, s=%d \n",
917 *(unsigned int *)(cookie->data), status);
918 if (!(block = nlmsvc_find_block(cookie)))
919 return;
920
921 if (block) {
922 if (status == nlm_lck_denied_grace_period) {
923 /* Try again in a couple of seconds */
924 nlmsvc_insert_block(block, 10 * HZ);
925 } else {
926 /* Lock is now held by client, or has been rejected.
927 * In both cases, the block should be removed. */
928 nlmsvc_unlink_block(block);
929 }
930 }
931 nlmsvc_release_block(block);
932}
933
934/* Helper function to handle retry of a deferred block.
935 * If it is a blocking lock, call grant_blocked.
936 * For a non-blocking lock or test lock, revisit the request.
937 */
938static void
939retry_deferred_block(struct nlm_block *block)
940{
941 if (!(block->b_flags & B_GOT_CALLBACK))
942 block->b_flags |= B_TIMED_OUT;
943 nlmsvc_insert_block(block, NLM_TIMEOUT);
944 dprintk("revisit block %p flags %d\n", block, block->b_flags);
945 if (block->b_deferred_req) {
946 block->b_deferred_req->revisit(block->b_deferred_req, 0);
947 block->b_deferred_req = NULL;
948 }
949}
950
951/*
952 * Retry all blocked locks that have been notified. This is where lockd
953 * picks up locks that can be granted, or grant notifications that must
954 * be retransmitted.
955 */
956unsigned long
957nlmsvc_retry_blocked(void)
958{
959 unsigned long timeout = MAX_SCHEDULE_TIMEOUT;
960 struct nlm_block *block;
961
962 spin_lock(&nlm_blocked_lock);
963 while (!list_empty(&nlm_blocked) && !kthread_should_stop()) {
964 block = list_entry(nlm_blocked.next, struct nlm_block, b_list);
965
966 if (block->b_when == NLM_NEVER)
967 break;
968 if (time_after(block->b_when, jiffies)) {
969 timeout = block->b_when - jiffies;
970 break;
971 }
972 spin_unlock(&nlm_blocked_lock);
973
974 dprintk("nlmsvc_retry_blocked(%p, when=%ld)\n",
975 block, block->b_when);
976 if (block->b_flags & B_QUEUED) {
977 dprintk("nlmsvc_retry_blocked delete block (%p, granted=%d, flags=%d)\n",
978 block, block->b_granted, block->b_flags);
979 retry_deferred_block(block);
980 } else
981 nlmsvc_grant_blocked(block);
982 spin_lock(&nlm_blocked_lock);
983 }
984 spin_unlock(&nlm_blocked_lock);
985
986 return timeout;
987}