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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * linux/fs/lockd/svclock.c
4 *
5 * Handling of server-side locks, mostly of the blocked variety.
6 * This is the ugliest part of lockd because we tread on very thin ice.
7 * GRANT and CANCEL calls may get stuck, meet in mid-flight, etc.
8 * IMNSHO introducing the grant callback into the NLM protocol was one
9 * of the worst ideas Sun ever had. Except maybe for the idea of doing
10 * NFS file locking at all.
11 *
12 * I'm trying hard to avoid race conditions by protecting most accesses
13 * to a file's list of blocked locks through a semaphore. The global
14 * list of blocked locks is not protected in this fashion however.
15 * Therefore, some functions (such as the RPC callback for the async grant
16 * call) move blocked locks towards the head of the list *while some other
17 * process might be traversing it*. This should not be a problem in
18 * practice, because this will only cause functions traversing the list
19 * to visit some blocks twice.
20 *
21 * Copyright (C) 1996, Olaf Kirch <okir@monad.swb.de>
22 */
23
24#include <linux/types.h>
25#include <linux/slab.h>
26#include <linux/errno.h>
27#include <linux/kernel.h>
28#include <linux/sched.h>
29#include <linux/sunrpc/clnt.h>
30#include <linux/sunrpc/svc_xprt.h>
31#include <linux/lockd/nlm.h>
32#include <linux/lockd/lockd.h>
33#include <linux/kthread.h>
34
35#define NLMDBG_FACILITY NLMDBG_SVCLOCK
36
37#ifdef CONFIG_LOCKD_V4
38#define nlm_deadlock nlm4_deadlock
39#else
40#define nlm_deadlock nlm_lck_denied
41#endif
42
43static void nlmsvc_release_block(struct nlm_block *block);
44static void nlmsvc_insert_block(struct nlm_block *block, unsigned long);
45static void nlmsvc_remove_block(struct nlm_block *block);
46
47static int nlmsvc_setgrantargs(struct nlm_rqst *call, struct nlm_lock *lock);
48static void nlmsvc_freegrantargs(struct nlm_rqst *call);
49static const struct rpc_call_ops nlmsvc_grant_ops;
50
51/*
52 * The list of blocked locks to retry
53 */
54static LIST_HEAD(nlm_blocked);
55static DEFINE_SPINLOCK(nlm_blocked_lock);
56
57#if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
58static const char *nlmdbg_cookie2a(const struct nlm_cookie *cookie)
59{
60 /*
61 * We can get away with a static buffer because this is only called
62 * from lockd, which is single-threaded.
63 */
64 static char buf[2*NLM_MAXCOOKIELEN+1];
65 unsigned int i, len = sizeof(buf);
66 char *p = buf;
67
68 len--; /* allow for trailing \0 */
69 if (len < 3)
70 return "???";
71 for (i = 0 ; i < cookie->len ; i++) {
72 if (len < 2) {
73 strcpy(p-3, "...");
74 break;
75 }
76 sprintf(p, "%02x", cookie->data[i]);
77 p += 2;
78 len -= 2;
79 }
80 *p = '\0';
81
82 return buf;
83}
84#endif
85
86/*
87 * Insert a blocked lock into the global list
88 */
89static void
90nlmsvc_insert_block_locked(struct nlm_block *block, unsigned long when)
91{
92 struct nlm_block *b;
93 struct list_head *pos;
94
95 dprintk("lockd: nlmsvc_insert_block(%p, %ld)\n", block, when);
96 if (list_empty(&block->b_list)) {
97 kref_get(&block->b_count);
98 } else {
99 list_del_init(&block->b_list);
100 }
101
102 pos = &nlm_blocked;
103 if (when != NLM_NEVER) {
104 if ((when += jiffies) == NLM_NEVER)
105 when ++;
106 list_for_each(pos, &nlm_blocked) {
107 b = list_entry(pos, struct nlm_block, b_list);
108 if (time_after(b->b_when,when) || b->b_when == NLM_NEVER)
109 break;
110 }
111 /* On normal exit from the loop, pos == &nlm_blocked,
112 * so we will be adding to the end of the list - good
113 */
114 }
115
116 list_add_tail(&block->b_list, pos);
117 block->b_when = when;
118}
119
120static void nlmsvc_insert_block(struct nlm_block *block, unsigned long when)
121{
122 spin_lock(&nlm_blocked_lock);
123 nlmsvc_insert_block_locked(block, when);
124 spin_unlock(&nlm_blocked_lock);
125}
126
127/*
128 * Remove a block from the global list
129 */
130static inline void
131nlmsvc_remove_block(struct nlm_block *block)
132{
133 if (!list_empty(&block->b_list)) {
134 spin_lock(&nlm_blocked_lock);
135 list_del_init(&block->b_list);
136 spin_unlock(&nlm_blocked_lock);
137 nlmsvc_release_block(block);
138 }
139}
140
141/*
142 * Find a block for a given lock
143 */
144static struct nlm_block *
145nlmsvc_lookup_block(struct nlm_file *file, struct nlm_lock *lock)
146{
147 struct nlm_block *block;
148 struct file_lock *fl;
149
150 dprintk("lockd: nlmsvc_lookup_block f=%p pd=%d %Ld-%Ld ty=%d\n",
151 file, lock->fl.fl_pid,
152 (long long)lock->fl.fl_start,
153 (long long)lock->fl.fl_end, lock->fl.fl_type);
154 list_for_each_entry(block, &nlm_blocked, b_list) {
155 fl = &block->b_call->a_args.lock.fl;
156 dprintk("lockd: check f=%p pd=%d %Ld-%Ld ty=%d cookie=%s\n",
157 block->b_file, fl->fl_pid,
158 (long long)fl->fl_start,
159 (long long)fl->fl_end, fl->fl_type,
160 nlmdbg_cookie2a(&block->b_call->a_args.cookie));
161 if (block->b_file == file && nlm_compare_locks(fl, &lock->fl)) {
162 kref_get(&block->b_count);
163 return block;
164 }
165 }
166
167 return NULL;
168}
169
170static inline int nlm_cookie_match(struct nlm_cookie *a, struct nlm_cookie *b)
171{
172 if (a->len != b->len)
173 return 0;
174 if (memcmp(a->data, b->data, a->len))
175 return 0;
176 return 1;
177}
178
179/*
180 * Find a block with a given NLM cookie.
181 */
182static inline struct nlm_block *
183nlmsvc_find_block(struct nlm_cookie *cookie)
184{
185 struct nlm_block *block;
186
187 list_for_each_entry(block, &nlm_blocked, b_list) {
188 if (nlm_cookie_match(&block->b_call->a_args.cookie,cookie))
189 goto found;
190 }
191
192 return NULL;
193
194found:
195 dprintk("nlmsvc_find_block(%s): block=%p\n", nlmdbg_cookie2a(cookie), block);
196 kref_get(&block->b_count);
197 return block;
198}
199
200/*
201 * Create a block and initialize it.
202 *
203 * Note: we explicitly set the cookie of the grant reply to that of
204 * the blocked lock request. The spec explicitly mentions that the client
205 * should _not_ rely on the callback containing the same cookie as the
206 * request, but (as I found out later) that's because some implementations
207 * do just this. Never mind the standards comittees, they support our
208 * logging industries.
209 *
210 * 10 years later: I hope we can safely ignore these old and broken
211 * clients by now. Let's fix this so we can uniquely identify an incoming
212 * GRANTED_RES message by cookie, without having to rely on the client's IP
213 * address. --okir
214 */
215static struct nlm_block *
216nlmsvc_create_block(struct svc_rqst *rqstp, struct nlm_host *host,
217 struct nlm_file *file, struct nlm_lock *lock,
218 struct nlm_cookie *cookie)
219{
220 struct nlm_block *block;
221 struct nlm_rqst *call = NULL;
222
223 call = nlm_alloc_call(host);
224 if (call == NULL)
225 return NULL;
226
227 /* Allocate memory for block, and initialize arguments */
228 block = kzalloc(sizeof(*block), GFP_KERNEL);
229 if (block == NULL)
230 goto failed;
231 kref_init(&block->b_count);
232 INIT_LIST_HEAD(&block->b_list);
233 INIT_LIST_HEAD(&block->b_flist);
234
235 if (!nlmsvc_setgrantargs(call, lock))
236 goto failed_free;
237
238 /* Set notifier function for VFS, and init args */
239 call->a_args.lock.fl.fl_flags |= FL_SLEEP;
240 call->a_args.lock.fl.fl_lmops = &nlmsvc_lock_operations;
241 nlmclnt_next_cookie(&call->a_args.cookie);
242
243 dprintk("lockd: created block %p...\n", block);
244
245 /* Create and initialize the block */
246 block->b_daemon = rqstp->rq_server;
247 block->b_host = host;
248 block->b_file = file;
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);
299}
300
301static void nlmsvc_release_block(struct nlm_block *block)
302{
303 if (block != NULL)
304 kref_put_mutex(&block->b_count, nlmsvc_free_block, &block->b_file->f_mutex);
305}
306
307/*
308 * Loop over all blocks and delete blocks held by
309 * a matching host.
310 */
311void nlmsvc_traverse_blocks(struct nlm_host *host,
312 struct nlm_file *file,
313 nlm_host_match_fn_t match)
314{
315 struct nlm_block *block, *next;
316
317restart:
318 mutex_lock(&file->f_mutex);
319 list_for_each_entry_safe(block, next, &file->f_blocks, b_flist) {
320 if (!match(block->b_host, host))
321 continue;
322 /* Do not destroy blocks that are not on
323 * the global retry list - why? */
324 if (list_empty(&block->b_list))
325 continue;
326 kref_get(&block->b_count);
327 mutex_unlock(&file->f_mutex);
328 nlmsvc_unlink_block(block);
329 nlmsvc_release_block(block);
330 goto restart;
331 }
332 mutex_unlock(&file->f_mutex);
333}
334
335/*
336 * Initialize arguments for GRANTED call. The nlm_rqst structure
337 * has been cleared already.
338 */
339static int nlmsvc_setgrantargs(struct nlm_rqst *call, struct nlm_lock *lock)
340{
341 locks_copy_lock(&call->a_args.lock.fl, &lock->fl);
342 memcpy(&call->a_args.lock.fh, &lock->fh, sizeof(call->a_args.lock.fh));
343 call->a_args.lock.caller = utsname()->nodename;
344 call->a_args.lock.oh.len = lock->oh.len;
345
346 /* set default data area */
347 call->a_args.lock.oh.data = call->a_owner;
348 call->a_args.lock.svid = lock->fl.fl_pid;
349
350 if (lock->oh.len > NLMCLNT_OHSIZE) {
351 void *data = kmalloc(lock->oh.len, GFP_KERNEL);
352 if (!data)
353 return 0;
354 call->a_args.lock.oh.data = (u8 *) data;
355 }
356
357 memcpy(call->a_args.lock.oh.data, lock->oh.data, lock->oh.len);
358 return 1;
359}
360
361static void nlmsvc_freegrantargs(struct nlm_rqst *call)
362{
363 if (call->a_args.lock.oh.data != call->a_owner)
364 kfree(call->a_args.lock.oh.data);
365
366 locks_release_private(&call->a_args.lock.fl);
367}
368
369/*
370 * Deferred lock request handling for non-blocking lock
371 */
372static __be32
373nlmsvc_defer_lock_rqst(struct svc_rqst *rqstp, struct nlm_block *block)
374{
375 __be32 status = nlm_lck_denied_nolocks;
376
377 block->b_flags |= B_QUEUED;
378
379 nlmsvc_insert_block(block, NLM_TIMEOUT);
380
381 block->b_cache_req = &rqstp->rq_chandle;
382 if (rqstp->rq_chandle.defer) {
383 block->b_deferred_req =
384 rqstp->rq_chandle.defer(block->b_cache_req);
385 if (block->b_deferred_req != NULL)
386 status = nlm_drop_reply;
387 }
388 dprintk("lockd: nlmsvc_defer_lock_rqst block %p flags %d status %d\n",
389 block, block->b_flags, ntohl(status));
390
391 return status;
392}
393
394/*
395 * Attempt to establish a lock, and if it can't be granted, block it
396 * if required.
397 */
398__be32
399nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file,
400 struct nlm_host *host, struct nlm_lock *lock, int wait,
401 struct nlm_cookie *cookie, int reclaim)
402{
403 struct nlm_block *block = NULL;
404 int error;
405 __be32 ret;
406
407 dprintk("lockd: nlmsvc_lock(%s/%ld, ty=%d, pi=%d, %Ld-%Ld, bl=%d)\n",
408 file_inode(file->f_file)->i_sb->s_id,
409 file_inode(file->f_file)->i_ino,
410 lock->fl.fl_type, lock->fl.fl_pid,
411 (long long)lock->fl.fl_start,
412 (long long)lock->fl.fl_end,
413 wait);
414
415 /* Lock file against concurrent access */
416 mutex_lock(&file->f_mutex);
417 /* Get existing block (in case client is busy-waiting)
418 * or create new block
419 */
420 block = nlmsvc_lookup_block(file, lock);
421 if (block == NULL) {
422 block = nlmsvc_create_block(rqstp, host, file, lock, cookie);
423 ret = nlm_lck_denied_nolocks;
424 if (block == NULL)
425 goto out;
426 lock = &block->b_call->a_args.lock;
427 } else
428 lock->fl.fl_flags &= ~FL_SLEEP;
429
430 if (block->b_flags & B_QUEUED) {
431 dprintk("lockd: nlmsvc_lock deferred block %p flags %d\n",
432 block, block->b_flags);
433 if (block->b_granted) {
434 nlmsvc_unlink_block(block);
435 ret = nlm_granted;
436 goto out;
437 }
438 if (block->b_flags & B_TIMED_OUT) {
439 nlmsvc_unlink_block(block);
440 ret = nlm_lck_denied;
441 goto out;
442 }
443 ret = nlm_drop_reply;
444 goto out;
445 }
446
447 if (locks_in_grace(SVC_NET(rqstp)) && !reclaim) {
448 ret = nlm_lck_denied_grace_period;
449 goto out;
450 }
451 if (reclaim && !locks_in_grace(SVC_NET(rqstp))) {
452 ret = nlm_lck_denied_grace_period;
453 goto out;
454 }
455
456 if (!wait)
457 lock->fl.fl_flags &= ~FL_SLEEP;
458 error = vfs_lock_file(file->f_file, F_SETLK, &lock->fl, NULL);
459 lock->fl.fl_flags &= ~FL_SLEEP;
460
461 dprintk("lockd: vfs_lock_file returned %d\n", error);
462 switch (error) {
463 case 0:
464 ret = nlm_granted;
465 goto out;
466 case -EAGAIN:
467 /*
468 * If this is a blocking request for an
469 * already pending lock request then we need
470 * to put it back on lockd's block list
471 */
472 if (wait)
473 break;
474 ret = nlm_lck_denied;
475 goto out;
476 case FILE_LOCK_DEFERRED:
477 if (wait)
478 break;
479 /* Filesystem lock operation is in progress
480 Add it to the queue waiting for callback */
481 ret = nlmsvc_defer_lock_rqst(rqstp, block);
482 goto out;
483 case -EDEADLK:
484 ret = nlm_deadlock;
485 goto out;
486 default: /* includes ENOLCK */
487 ret = nlm_lck_denied_nolocks;
488 goto out;
489 }
490
491 ret = nlm_lck_blocked;
492
493 /* Append to list of blocked */
494 nlmsvc_insert_block(block, NLM_NEVER);
495out:
496 mutex_unlock(&file->f_mutex);
497 nlmsvc_release_block(block);
498 dprintk("lockd: nlmsvc_lock returned %u\n", ret);
499 return ret;
500}
501
502/*
503 * Test for presence of a conflicting lock.
504 */
505__be32
506nlmsvc_testlock(struct svc_rqst *rqstp, struct nlm_file *file,
507 struct nlm_host *host, struct nlm_lock *lock,
508 struct nlm_lock *conflock, struct nlm_cookie *cookie)
509{
510 int error;
511 __be32 ret;
512
513 dprintk("lockd: nlmsvc_testlock(%s/%ld, ty=%d, %Ld-%Ld)\n",
514 file_inode(file->f_file)->i_sb->s_id,
515 file_inode(file->f_file)->i_ino,
516 lock->fl.fl_type,
517 (long long)lock->fl.fl_start,
518 (long long)lock->fl.fl_end);
519
520 if (locks_in_grace(SVC_NET(rqstp))) {
521 ret = nlm_lck_denied_grace_period;
522 goto out;
523 }
524
525 error = vfs_test_lock(file->f_file, &lock->fl);
526 if (error) {
527 /* We can't currently deal with deferred test requests */
528 if (error == FILE_LOCK_DEFERRED)
529 WARN_ON_ONCE(1);
530
531 ret = nlm_lck_denied_nolocks;
532 goto out;
533 }
534
535 if (lock->fl.fl_type == F_UNLCK) {
536 ret = nlm_granted;
537 goto out;
538 }
539
540 dprintk("lockd: conflicting lock(ty=%d, %Ld-%Ld)\n",
541 lock->fl.fl_type, (long long)lock->fl.fl_start,
542 (long long)lock->fl.fl_end);
543 conflock->caller = "somehost"; /* FIXME */
544 conflock->len = strlen(conflock->caller);
545 conflock->oh.len = 0; /* don't return OH info */
546 conflock->svid = lock->fl.fl_pid;
547 conflock->fl.fl_type = lock->fl.fl_type;
548 conflock->fl.fl_start = lock->fl.fl_start;
549 conflock->fl.fl_end = lock->fl.fl_end;
550 locks_release_private(&lock->fl);
551 ret = nlm_lck_denied;
552out:
553 return ret;
554}
555
556/*
557 * Remove a lock.
558 * This implies a CANCEL call: We send a GRANT_MSG, the client replies
559 * with a GRANT_RES call which gets lost, and calls UNLOCK immediately
560 * afterwards. In this case the block will still be there, and hence
561 * must be removed.
562 */
563__be32
564nlmsvc_unlock(struct net *net, struct nlm_file *file, struct nlm_lock *lock)
565{
566 int error;
567
568 dprintk("lockd: nlmsvc_unlock(%s/%ld, pi=%d, %Ld-%Ld)\n",
569 file_inode(file->f_file)->i_sb->s_id,
570 file_inode(file->f_file)->i_ino,
571 lock->fl.fl_pid,
572 (long long)lock->fl.fl_start,
573 (long long)lock->fl.fl_end);
574
575 /* First, cancel any lock that might be there */
576 nlmsvc_cancel_blocked(net, file, lock);
577
578 lock->fl.fl_type = F_UNLCK;
579 error = vfs_lock_file(file->f_file, F_SETLK, &lock->fl, NULL);
580
581 return (error < 0)? nlm_lck_denied_nolocks : nlm_granted;
582}
583
584/*
585 * Cancel a previously blocked request.
586 *
587 * A cancel request always overrides any grant that may currently
588 * be in progress.
589 * The calling procedure must check whether the file can be closed.
590 */
591__be32
592nlmsvc_cancel_blocked(struct net *net, struct nlm_file *file, struct nlm_lock *lock)
593{
594 struct nlm_block *block;
595 int status = 0;
596
597 dprintk("lockd: nlmsvc_cancel(%s/%ld, pi=%d, %Ld-%Ld)\n",
598 file_inode(file->f_file)->i_sb->s_id,
599 file_inode(file->f_file)->i_ino,
600 lock->fl.fl_pid,
601 (long long)lock->fl.fl_start,
602 (long long)lock->fl.fl_end);
603
604 if (locks_in_grace(net))
605 return nlm_lck_denied_grace_period;
606
607 mutex_lock(&file->f_mutex);
608 block = nlmsvc_lookup_block(file, lock);
609 mutex_unlock(&file->f_mutex);
610 if (block != NULL) {
611 vfs_cancel_lock(block->b_file->f_file,
612 &block->b_call->a_args.lock.fl);
613 status = nlmsvc_unlink_block(block);
614 nlmsvc_release_block(block);
615 }
616 return status ? nlm_lck_denied : nlm_granted;
617}
618
619/*
620 * This is a callback from the filesystem for VFS file lock requests.
621 * It will be used if lm_grant is defined and the filesystem can not
622 * respond to the request immediately.
623 * For SETLK or SETLKW request it will get the local posix lock.
624 * In all cases it will move the block to the head of nlm_blocked q where
625 * nlmsvc_retry_blocked() can send back a reply for SETLKW or revisit the
626 * deferred rpc for GETLK and SETLK.
627 */
628static void
629nlmsvc_update_deferred_block(struct nlm_block *block, int result)
630{
631 block->b_flags |= B_GOT_CALLBACK;
632 if (result == 0)
633 block->b_granted = 1;
634 else
635 block->b_flags |= B_TIMED_OUT;
636}
637
638static int nlmsvc_grant_deferred(struct file_lock *fl, int result)
639{
640 struct nlm_block *block;
641 int rc = -ENOENT;
642
643 spin_lock(&nlm_blocked_lock);
644 list_for_each_entry(block, &nlm_blocked, b_list) {
645 if (nlm_compare_locks(&block->b_call->a_args.lock.fl, fl)) {
646 dprintk("lockd: nlmsvc_notify_blocked block %p flags %d\n",
647 block, block->b_flags);
648 if (block->b_flags & B_QUEUED) {
649 if (block->b_flags & B_TIMED_OUT) {
650 rc = -ENOLCK;
651 break;
652 }
653 nlmsvc_update_deferred_block(block, result);
654 } else if (result == 0)
655 block->b_granted = 1;
656
657 nlmsvc_insert_block_locked(block, 0);
658 svc_wake_up(block->b_daemon);
659 rc = 0;
660 break;
661 }
662 }
663 spin_unlock(&nlm_blocked_lock);
664 if (rc == -ENOENT)
665 printk(KERN_WARNING "lockd: grant for unknown block\n");
666 return rc;
667}
668
669/*
670 * Unblock a blocked lock request. This is a callback invoked from the
671 * VFS layer when a lock on which we blocked is removed.
672 *
673 * This function doesn't grant the blocked lock instantly, but rather moves
674 * the block to the head of nlm_blocked where it can be picked up by lockd.
675 */
676static void
677nlmsvc_notify_blocked(struct file_lock *fl)
678{
679 struct nlm_block *block;
680
681 dprintk("lockd: VFS unblock notification for block %p\n", fl);
682 spin_lock(&nlm_blocked_lock);
683 list_for_each_entry(block, &nlm_blocked, b_list) {
684 if (nlm_compare_locks(&block->b_call->a_args.lock.fl, fl)) {
685 nlmsvc_insert_block_locked(block, 0);
686 spin_unlock(&nlm_blocked_lock);
687 svc_wake_up(block->b_daemon);
688 return;
689 }
690 }
691 spin_unlock(&nlm_blocked_lock);
692 printk(KERN_WARNING "lockd: notification for unknown block!\n");
693}
694
695static int nlmsvc_same_owner(struct file_lock *fl1, struct file_lock *fl2)
696{
697 return fl1->fl_owner == fl2->fl_owner && fl1->fl_pid == fl2->fl_pid;
698}
699
700/*
701 * Since NLM uses two "keys" for tracking locks, we need to hash them down
702 * to one for the blocked_hash. Here, we're just xor'ing the host address
703 * with the pid in order to create a key value for picking a hash bucket.
704 */
705static unsigned long
706nlmsvc_owner_key(struct file_lock *fl)
707{
708 return (unsigned long)fl->fl_owner ^ (unsigned long)fl->fl_pid;
709}
710
711const struct lock_manager_operations nlmsvc_lock_operations = {
712 .lm_compare_owner = nlmsvc_same_owner,
713 .lm_owner_key = nlmsvc_owner_key,
714 .lm_notify = nlmsvc_notify_blocked,
715 .lm_grant = nlmsvc_grant_deferred,
716};
717
718/*
719 * Try to claim a lock that was previously blocked.
720 *
721 * Note that we use both the RPC_GRANTED_MSG call _and_ an async
722 * RPC thread when notifying the client. This seems like overkill...
723 * Here's why:
724 * - we don't want to use a synchronous RPC thread, otherwise
725 * we might find ourselves hanging on a dead portmapper.
726 * - Some lockd implementations (e.g. HP) don't react to
727 * RPC_GRANTED calls; they seem to insist on RPC_GRANTED_MSG calls.
728 */
729static void
730nlmsvc_grant_blocked(struct nlm_block *block)
731{
732 struct nlm_file *file = block->b_file;
733 struct nlm_lock *lock = &block->b_call->a_args.lock;
734 int error;
735 loff_t fl_start, fl_end;
736
737 dprintk("lockd: grant blocked lock %p\n", block);
738
739 kref_get(&block->b_count);
740
741 /* Unlink block request from list */
742 nlmsvc_unlink_block(block);
743
744 /* If b_granted is true this means we've been here before.
745 * Just retry the grant callback, possibly refreshing the RPC
746 * binding */
747 if (block->b_granted) {
748 nlm_rebind_host(block->b_host);
749 goto callback;
750 }
751
752 /* Try the lock operation again */
753 /* vfs_lock_file() can mangle fl_start and fl_end, but we need
754 * them unchanged for the GRANT_MSG
755 */
756 lock->fl.fl_flags |= FL_SLEEP;
757 fl_start = lock->fl.fl_start;
758 fl_end = lock->fl.fl_end;
759 error = vfs_lock_file(file->f_file, F_SETLK, &lock->fl, NULL);
760 lock->fl.fl_flags &= ~FL_SLEEP;
761 lock->fl.fl_start = fl_start;
762 lock->fl.fl_end = fl_end;
763
764 switch (error) {
765 case 0:
766 break;
767 case FILE_LOCK_DEFERRED:
768 dprintk("lockd: lock still blocked error %d\n", error);
769 nlmsvc_insert_block(block, NLM_NEVER);
770 nlmsvc_release_block(block);
771 return;
772 default:
773 printk(KERN_WARNING "lockd: unexpected error %d in %s!\n",
774 -error, __func__);
775 nlmsvc_insert_block(block, 10 * HZ);
776 nlmsvc_release_block(block);
777 return;
778 }
779
780callback:
781 /* Lock was granted by VFS. */
782 dprintk("lockd: GRANTing blocked lock.\n");
783 block->b_granted = 1;
784
785 /* keep block on the list, but don't reattempt until the RPC
786 * completes or the submission fails
787 */
788 nlmsvc_insert_block(block, NLM_NEVER);
789
790 /* Call the client -- use a soft RPC task since nlmsvc_retry_blocked
791 * will queue up a new one if this one times out
792 */
793 error = nlm_async_call(block->b_call, NLMPROC_GRANTED_MSG,
794 &nlmsvc_grant_ops);
795
796 /* RPC submission failed, wait a bit and retry */
797 if (error < 0)
798 nlmsvc_insert_block(block, 10 * HZ);
799}
800
801/*
802 * This is the callback from the RPC layer when the NLM_GRANTED_MSG
803 * RPC call has succeeded or timed out.
804 * Like all RPC callbacks, it is invoked by the rpciod process, so it
805 * better not sleep. Therefore, we put the blocked lock on the nlm_blocked
806 * chain once more in order to have it removed by lockd itself (which can
807 * then sleep on the file semaphore without disrupting e.g. the nfs client).
808 */
809static void nlmsvc_grant_callback(struct rpc_task *task, void *data)
810{
811 struct nlm_rqst *call = data;
812 struct nlm_block *block = call->a_block;
813 unsigned long timeout;
814
815 dprintk("lockd: GRANT_MSG RPC callback\n");
816
817 spin_lock(&nlm_blocked_lock);
818 /* if the block is not on a list at this point then it has
819 * been invalidated. Don't try to requeue it.
820 *
821 * FIXME: it's possible that the block is removed from the list
822 * after this check but before the nlmsvc_insert_block. In that
823 * case it will be added back. Perhaps we need better locking
824 * for nlm_blocked?
825 */
826 if (list_empty(&block->b_list))
827 goto out;
828
829 /* Technically, we should down the file semaphore here. Since we
830 * move the block towards the head of the queue only, no harm
831 * can be done, though. */
832 if (task->tk_status < 0) {
833 /* RPC error: Re-insert for retransmission */
834 timeout = 10 * HZ;
835 } else {
836 /* Call was successful, now wait for client callback */
837 timeout = 60 * HZ;
838 }
839 nlmsvc_insert_block_locked(block, timeout);
840 svc_wake_up(block->b_daemon);
841out:
842 spin_unlock(&nlm_blocked_lock);
843}
844
845/*
846 * FIXME: nlmsvc_release_block() grabs a mutex. This is not allowed for an
847 * .rpc_release rpc_call_op
848 */
849static void nlmsvc_grant_release(void *data)
850{
851 struct nlm_rqst *call = data;
852 nlmsvc_release_block(call->a_block);
853}
854
855static const struct rpc_call_ops nlmsvc_grant_ops = {
856 .rpc_call_done = nlmsvc_grant_callback,
857 .rpc_release = nlmsvc_grant_release,
858};
859
860/*
861 * We received a GRANT_RES callback. Try to find the corresponding
862 * block.
863 */
864void
865nlmsvc_grant_reply(struct nlm_cookie *cookie, __be32 status)
866{
867 struct nlm_block *block;
868
869 dprintk("grant_reply: looking for cookie %x, s=%d \n",
870 *(unsigned int *)(cookie->data), status);
871 if (!(block = nlmsvc_find_block(cookie)))
872 return;
873
874 if (status == nlm_lck_denied_grace_period) {
875 /* Try again in a couple of seconds */
876 nlmsvc_insert_block(block, 10 * HZ);
877 } else {
878 /*
879 * Lock is now held by client, or has been rejected.
880 * In both cases, the block should be removed.
881 */
882 nlmsvc_unlink_block(block);
883 }
884 nlmsvc_release_block(block);
885}
886
887/* Helper function to handle retry of a deferred block.
888 * If it is a blocking lock, call grant_blocked.
889 * For a non-blocking lock or test lock, revisit the request.
890 */
891static void
892retry_deferred_block(struct nlm_block *block)
893{
894 if (!(block->b_flags & B_GOT_CALLBACK))
895 block->b_flags |= B_TIMED_OUT;
896 nlmsvc_insert_block(block, NLM_TIMEOUT);
897 dprintk("revisit block %p flags %d\n", block, block->b_flags);
898 if (block->b_deferred_req) {
899 block->b_deferred_req->revisit(block->b_deferred_req, 0);
900 block->b_deferred_req = NULL;
901 }
902}
903
904/*
905 * Retry all blocked locks that have been notified. This is where lockd
906 * picks up locks that can be granted, or grant notifications that must
907 * be retransmitted.
908 */
909unsigned long
910nlmsvc_retry_blocked(void)
911{
912 unsigned long timeout = MAX_SCHEDULE_TIMEOUT;
913 struct nlm_block *block;
914
915 spin_lock(&nlm_blocked_lock);
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 spin_unlock(&nlm_blocked_lock);
926
927 dprintk("nlmsvc_retry_blocked(%p, when=%ld)\n",
928 block, block->b_when);
929 if (block->b_flags & B_QUEUED) {
930 dprintk("nlmsvc_retry_blocked delete block (%p, granted=%d, flags=%d)\n",
931 block, block->b_granted, block->b_flags);
932 retry_deferred_block(block);
933 } else
934 nlmsvc_grant_blocked(block);
935 spin_lock(&nlm_blocked_lock);
936 }
937 spin_unlock(&nlm_blocked_lock);
938
939 return timeout;
940}
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}