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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.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 nlm_get_host(host);
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 block->b_fl = NULL;
250 file->f_count++;
251
252 /* Add to file's list of blocks */
253 list_add(&block->b_flist, &file->f_blocks);
254
255 /* Set up RPC arguments for callback */
256 block->b_call = call;
257 call->a_flags = RPC_TASK_ASYNC;
258 call->a_block = block;
259
260 return block;
261
262failed_free:
263 kfree(block);
264failed:
265 nlmsvc_release_call(call);
266 return NULL;
267}
268
269/*
270 * Delete a block.
271 * It is the caller's responsibility to check whether the file
272 * can be closed hereafter.
273 */
274static int nlmsvc_unlink_block(struct nlm_block *block)
275{
276 int status;
277 dprintk("lockd: unlinking block %p...\n", block);
278
279 /* Remove block from list */
280 status = posix_unblock_lock(block->b_file->f_file, &block->b_call->a_args.lock.fl);
281 nlmsvc_remove_block(block);
282 return status;
283}
284
285static void nlmsvc_free_block(struct kref *kref)
286{
287 struct nlm_block *block = container_of(kref, struct nlm_block, b_count);
288 struct nlm_file *file = block->b_file;
289
290 dprintk("lockd: freeing block %p...\n", block);
291
292 /* Remove block from file's list of blocks */
293 mutex_lock(&file->f_mutex);
294 list_del_init(&block->b_flist);
295 mutex_unlock(&file->f_mutex);
296
297 nlmsvc_freegrantargs(block->b_call);
298 nlmsvc_release_call(block->b_call);
299 nlm_release_file(block->b_file);
300 kfree(block->b_fl);
301 kfree(block);
302}
303
304static void nlmsvc_release_block(struct nlm_block *block)
305{
306 if (block != NULL)
307 kref_put(&block->b_count, nlmsvc_free_block);
308}
309
310/*
311 * Loop over all blocks and delete blocks held by
312 * a matching host.
313 */
314void nlmsvc_traverse_blocks(struct nlm_host *host,
315 struct nlm_file *file,
316 nlm_host_match_fn_t match)
317{
318 struct nlm_block *block, *next;
319
320restart:
321 mutex_lock(&file->f_mutex);
322 list_for_each_entry_safe(block, next, &file->f_blocks, b_flist) {
323 if (!match(block->b_host, host))
324 continue;
325 /* Do not destroy blocks that are not on
326 * the global retry list - why? */
327 if (list_empty(&block->b_list))
328 continue;
329 kref_get(&block->b_count);
330 mutex_unlock(&file->f_mutex);
331 nlmsvc_unlink_block(block);
332 nlmsvc_release_block(block);
333 goto restart;
334 }
335 mutex_unlock(&file->f_mutex);
336}
337
338/*
339 * Initialize arguments for GRANTED call. The nlm_rqst structure
340 * has been cleared already.
341 */
342static int nlmsvc_setgrantargs(struct nlm_rqst *call, struct nlm_lock *lock)
343{
344 locks_copy_lock(&call->a_args.lock.fl, &lock->fl);
345 memcpy(&call->a_args.lock.fh, &lock->fh, sizeof(call->a_args.lock.fh));
346 call->a_args.lock.caller = utsname()->nodename;
347 call->a_args.lock.oh.len = lock->oh.len;
348
349 /* set default data area */
350 call->a_args.lock.oh.data = call->a_owner;
351 call->a_args.lock.svid = lock->fl.fl_pid;
352
353 if (lock->oh.len > NLMCLNT_OHSIZE) {
354 void *data = kmalloc(lock->oh.len, GFP_KERNEL);
355 if (!data)
356 return 0;
357 call->a_args.lock.oh.data = (u8 *) data;
358 }
359
360 memcpy(call->a_args.lock.oh.data, lock->oh.data, lock->oh.len);
361 return 1;
362}
363
364static void nlmsvc_freegrantargs(struct nlm_rqst *call)
365{
366 if (call->a_args.lock.oh.data != call->a_owner)
367 kfree(call->a_args.lock.oh.data);
368
369 locks_release_private(&call->a_args.lock.fl);
370}
371
372/*
373 * Deferred lock request handling for non-blocking lock
374 */
375static __be32
376nlmsvc_defer_lock_rqst(struct svc_rqst *rqstp, struct nlm_block *block)
377{
378 __be32 status = nlm_lck_denied_nolocks;
379
380 block->b_flags |= B_QUEUED;
381
382 nlmsvc_insert_block(block, NLM_TIMEOUT);
383
384 block->b_cache_req = &rqstp->rq_chandle;
385 if (rqstp->rq_chandle.defer) {
386 block->b_deferred_req =
387 rqstp->rq_chandle.defer(block->b_cache_req);
388 if (block->b_deferred_req != NULL)
389 status = nlm_drop_reply;
390 }
391 dprintk("lockd: nlmsvc_defer_lock_rqst block %p flags %d status %d\n",
392 block, block->b_flags, ntohl(status));
393
394 return status;
395}
396
397/*
398 * Attempt to establish a lock, and if it can't be granted, block it
399 * if required.
400 */
401__be32
402nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file,
403 struct nlm_host *host, struct nlm_lock *lock, int wait,
404 struct nlm_cookie *cookie, int reclaim)
405{
406 struct nlm_block *block = NULL;
407 int error;
408 __be32 ret;
409
410 dprintk("lockd: nlmsvc_lock(%s/%ld, ty=%d, pi=%d, %Ld-%Ld, bl=%d)\n",
411 file->f_file->f_path.dentry->d_inode->i_sb->s_id,
412 file->f_file->f_path.dentry->d_inode->i_ino,
413 lock->fl.fl_type, lock->fl.fl_pid,
414 (long long)lock->fl.fl_start,
415 (long long)lock->fl.fl_end,
416 wait);
417
418 /* Lock file against concurrent access */
419 mutex_lock(&file->f_mutex);
420 /* Get existing block (in case client is busy-waiting)
421 * or create new block
422 */
423 block = nlmsvc_lookup_block(file, lock);
424 if (block == NULL) {
425 block = nlmsvc_create_block(rqstp, host, file, lock, cookie);
426 ret = nlm_lck_denied_nolocks;
427 if (block == NULL)
428 goto out;
429 lock = &block->b_call->a_args.lock;
430 } else
431 lock->fl.fl_flags &= ~FL_SLEEP;
432
433 if (block->b_flags & B_QUEUED) {
434 dprintk("lockd: nlmsvc_lock deferred block %p flags %d\n",
435 block, block->b_flags);
436 if (block->b_granted) {
437 nlmsvc_unlink_block(block);
438 ret = nlm_granted;
439 goto out;
440 }
441 if (block->b_flags & B_TIMED_OUT) {
442 nlmsvc_unlink_block(block);
443 ret = nlm_lck_denied;
444 goto out;
445 }
446 ret = nlm_drop_reply;
447 goto out;
448 }
449
450 if (locks_in_grace() && !reclaim) {
451 ret = nlm_lck_denied_grace_period;
452 goto out;
453 }
454 if (reclaim && !locks_in_grace()) {
455 ret = nlm_lck_denied_grace_period;
456 goto out;
457 }
458
459 if (!wait)
460 lock->fl.fl_flags &= ~FL_SLEEP;
461 error = vfs_lock_file(file->f_file, F_SETLK, &lock->fl, NULL);
462 lock->fl.fl_flags &= ~FL_SLEEP;
463
464 dprintk("lockd: vfs_lock_file returned %d\n", error);
465 switch (error) {
466 case 0:
467 ret = nlm_granted;
468 goto out;
469 case -EAGAIN:
470 /*
471 * If this is a blocking request for an
472 * already pending lock request then we need
473 * to put it back on lockd's block list
474 */
475 if (wait)
476 break;
477 ret = nlm_lck_denied;
478 goto out;
479 case FILE_LOCK_DEFERRED:
480 if (wait)
481 break;
482 /* Filesystem lock operation is in progress
483 Add it to the queue waiting for callback */
484 ret = nlmsvc_defer_lock_rqst(rqstp, block);
485 goto out;
486 case -EDEADLK:
487 ret = nlm_deadlock;
488 goto out;
489 default: /* includes ENOLCK */
490 ret = nlm_lck_denied_nolocks;
491 goto out;
492 }
493
494 ret = nlm_lck_blocked;
495
496 /* Append to list of blocked */
497 nlmsvc_insert_block(block, NLM_NEVER);
498out:
499 mutex_unlock(&file->f_mutex);
500 nlmsvc_release_block(block);
501 dprintk("lockd: nlmsvc_lock returned %u\n", ret);
502 return ret;
503}
504
505/*
506 * Test for presence of a conflicting lock.
507 */
508__be32
509nlmsvc_testlock(struct svc_rqst *rqstp, struct nlm_file *file,
510 struct nlm_host *host, struct nlm_lock *lock,
511 struct nlm_lock *conflock, struct nlm_cookie *cookie)
512{
513 struct nlm_block *block = NULL;
514 int error;
515 __be32 ret;
516
517 dprintk("lockd: nlmsvc_testlock(%s/%ld, ty=%d, %Ld-%Ld)\n",
518 file->f_file->f_path.dentry->d_inode->i_sb->s_id,
519 file->f_file->f_path.dentry->d_inode->i_ino,
520 lock->fl.fl_type,
521 (long long)lock->fl.fl_start,
522 (long long)lock->fl.fl_end);
523
524 /* Get existing block (in case client is busy-waiting) */
525 block = nlmsvc_lookup_block(file, lock);
526
527 if (block == NULL) {
528 struct file_lock *conf = kzalloc(sizeof(*conf), GFP_KERNEL);
529
530 if (conf == NULL)
531 return nlm_granted;
532 block = nlmsvc_create_block(rqstp, host, file, lock, cookie);
533 if (block == NULL) {
534 kfree(conf);
535 return nlm_granted;
536 }
537 block->b_fl = conf;
538 }
539 if (block->b_flags & B_QUEUED) {
540 dprintk("lockd: nlmsvc_testlock deferred block %p flags %d fl %p\n",
541 block, block->b_flags, block->b_fl);
542 if (block->b_flags & B_TIMED_OUT) {
543 nlmsvc_unlink_block(block);
544 ret = nlm_lck_denied;
545 goto out;
546 }
547 if (block->b_flags & B_GOT_CALLBACK) {
548 nlmsvc_unlink_block(block);
549 if (block->b_fl != NULL
550 && block->b_fl->fl_type != F_UNLCK) {
551 lock->fl = *block->b_fl;
552 goto conf_lock;
553 } else {
554 ret = nlm_granted;
555 goto out;
556 }
557 }
558 ret = nlm_drop_reply;
559 goto out;
560 }
561
562 if (locks_in_grace()) {
563 ret = nlm_lck_denied_grace_period;
564 goto out;
565 }
566 error = vfs_test_lock(file->f_file, &lock->fl);
567 if (error == FILE_LOCK_DEFERRED) {
568 ret = nlmsvc_defer_lock_rqst(rqstp, block);
569 goto out;
570 }
571 if (error) {
572 ret = nlm_lck_denied_nolocks;
573 goto out;
574 }
575 if (lock->fl.fl_type == F_UNLCK) {
576 ret = nlm_granted;
577 goto out;
578 }
579
580conf_lock:
581 dprintk("lockd: conflicting lock(ty=%d, %Ld-%Ld)\n",
582 lock->fl.fl_type, (long long)lock->fl.fl_start,
583 (long long)lock->fl.fl_end);
584 conflock->caller = "somehost"; /* FIXME */
585 conflock->len = strlen(conflock->caller);
586 conflock->oh.len = 0; /* don't return OH info */
587 conflock->svid = lock->fl.fl_pid;
588 conflock->fl.fl_type = lock->fl.fl_type;
589 conflock->fl.fl_start = lock->fl.fl_start;
590 conflock->fl.fl_end = lock->fl.fl_end;
591 ret = nlm_lck_denied;
592out:
593 if (block)
594 nlmsvc_release_block(block);
595 return ret;
596}
597
598/*
599 * Remove a lock.
600 * This implies a CANCEL call: We send a GRANT_MSG, the client replies
601 * with a GRANT_RES call which gets lost, and calls UNLOCK immediately
602 * afterwards. In this case the block will still be there, and hence
603 * must be removed.
604 */
605__be32
606nlmsvc_unlock(struct nlm_file *file, struct nlm_lock *lock)
607{
608 int error;
609
610 dprintk("lockd: nlmsvc_unlock(%s/%ld, pi=%d, %Ld-%Ld)\n",
611 file->f_file->f_path.dentry->d_inode->i_sb->s_id,
612 file->f_file->f_path.dentry->d_inode->i_ino,
613 lock->fl.fl_pid,
614 (long long)lock->fl.fl_start,
615 (long long)lock->fl.fl_end);
616
617 /* First, cancel any lock that might be there */
618 nlmsvc_cancel_blocked(file, lock);
619
620 lock->fl.fl_type = F_UNLCK;
621 error = vfs_lock_file(file->f_file, F_SETLK, &lock->fl, NULL);
622
623 return (error < 0)? nlm_lck_denied_nolocks : nlm_granted;
624}
625
626/*
627 * Cancel a previously blocked request.
628 *
629 * A cancel request always overrides any grant that may currently
630 * be in progress.
631 * The calling procedure must check whether the file can be closed.
632 */
633__be32
634nlmsvc_cancel_blocked(struct nlm_file *file, struct nlm_lock *lock)
635{
636 struct nlm_block *block;
637 int status = 0;
638
639 dprintk("lockd: nlmsvc_cancel(%s/%ld, pi=%d, %Ld-%Ld)\n",
640 file->f_file->f_path.dentry->d_inode->i_sb->s_id,
641 file->f_file->f_path.dentry->d_inode->i_ino,
642 lock->fl.fl_pid,
643 (long long)lock->fl.fl_start,
644 (long long)lock->fl.fl_end);
645
646 if (locks_in_grace())
647 return nlm_lck_denied_grace_period;
648
649 mutex_lock(&file->f_mutex);
650 block = nlmsvc_lookup_block(file, lock);
651 mutex_unlock(&file->f_mutex);
652 if (block != NULL) {
653 vfs_cancel_lock(block->b_file->f_file,
654 &block->b_call->a_args.lock.fl);
655 status = nlmsvc_unlink_block(block);
656 nlmsvc_release_block(block);
657 }
658 return status ? nlm_lck_denied : nlm_granted;
659}
660
661/*
662 * This is a callback from the filesystem for VFS file lock requests.
663 * It will be used if lm_grant is defined and the filesystem can not
664 * respond to the request immediately.
665 * For GETLK request it will copy the reply to the nlm_block.
666 * For SETLK or SETLKW request it will get the local posix lock.
667 * In all cases it will move the block to the head of nlm_blocked q where
668 * nlmsvc_retry_blocked() can send back a reply for SETLKW or revisit the
669 * deferred rpc for GETLK and SETLK.
670 */
671static void
672nlmsvc_update_deferred_block(struct nlm_block *block, struct file_lock *conf,
673 int result)
674{
675 block->b_flags |= B_GOT_CALLBACK;
676 if (result == 0)
677 block->b_granted = 1;
678 else
679 block->b_flags |= B_TIMED_OUT;
680 if (conf) {
681 if (block->b_fl)
682 __locks_copy_lock(block->b_fl, conf);
683 }
684}
685
686static int nlmsvc_grant_deferred(struct file_lock *fl, struct file_lock *conf,
687 int result)
688{
689 struct nlm_block *block;
690 int rc = -ENOENT;
691
692 spin_lock(&nlm_blocked_lock);
693 list_for_each_entry(block, &nlm_blocked, b_list) {
694 if (nlm_compare_locks(&block->b_call->a_args.lock.fl, fl)) {
695 dprintk("lockd: nlmsvc_notify_blocked block %p flags %d\n",
696 block, block->b_flags);
697 if (block->b_flags & B_QUEUED) {
698 if (block->b_flags & B_TIMED_OUT) {
699 rc = -ENOLCK;
700 break;
701 }
702 nlmsvc_update_deferred_block(block, conf, result);
703 } else if (result == 0)
704 block->b_granted = 1;
705
706 nlmsvc_insert_block_locked(block, 0);
707 svc_wake_up(block->b_daemon);
708 rc = 0;
709 break;
710 }
711 }
712 spin_unlock(&nlm_blocked_lock);
713 if (rc == -ENOENT)
714 printk(KERN_WARNING "lockd: grant for unknown block\n");
715 return rc;
716}
717
718/*
719 * Unblock a blocked lock request. This is a callback invoked from the
720 * VFS layer when a lock on which we blocked is removed.
721 *
722 * This function doesn't grant the blocked lock instantly, but rather moves
723 * the block to the head of nlm_blocked where it can be picked up by lockd.
724 */
725static void
726nlmsvc_notify_blocked(struct file_lock *fl)
727{
728 struct nlm_block *block;
729
730 dprintk("lockd: VFS unblock notification for block %p\n", fl);
731 spin_lock(&nlm_blocked_lock);
732 list_for_each_entry(block, &nlm_blocked, b_list) {
733 if (nlm_compare_locks(&block->b_call->a_args.lock.fl, fl)) {
734 nlmsvc_insert_block_locked(block, 0);
735 spin_unlock(&nlm_blocked_lock);
736 svc_wake_up(block->b_daemon);
737 return;
738 }
739 }
740 spin_unlock(&nlm_blocked_lock);
741 printk(KERN_WARNING "lockd: notification for unknown block!\n");
742}
743
744static int nlmsvc_same_owner(struct file_lock *fl1, struct file_lock *fl2)
745{
746 return fl1->fl_owner == fl2->fl_owner && fl1->fl_pid == fl2->fl_pid;
747}
748
749const struct lock_manager_operations nlmsvc_lock_operations = {
750 .lm_compare_owner = nlmsvc_same_owner,
751 .lm_notify = nlmsvc_notify_blocked,
752 .lm_grant = nlmsvc_grant_deferred,
753};
754
755/*
756 * Try to claim a lock that was previously blocked.
757 *
758 * Note that we use both the RPC_GRANTED_MSG call _and_ an async
759 * RPC thread when notifying the client. This seems like overkill...
760 * Here's why:
761 * - we don't want to use a synchronous RPC thread, otherwise
762 * we might find ourselves hanging on a dead portmapper.
763 * - Some lockd implementations (e.g. HP) don't react to
764 * RPC_GRANTED calls; they seem to insist on RPC_GRANTED_MSG calls.
765 */
766static void
767nlmsvc_grant_blocked(struct nlm_block *block)
768{
769 struct nlm_file *file = block->b_file;
770 struct nlm_lock *lock = &block->b_call->a_args.lock;
771 int error;
772
773 dprintk("lockd: grant blocked lock %p\n", block);
774
775 kref_get(&block->b_count);
776
777 /* Unlink block request from list */
778 nlmsvc_unlink_block(block);
779
780 /* If b_granted is true this means we've been here before.
781 * Just retry the grant callback, possibly refreshing the RPC
782 * binding */
783 if (block->b_granted) {
784 nlm_rebind_host(block->b_host);
785 goto callback;
786 }
787
788 /* Try the lock operation again */
789 lock->fl.fl_flags |= FL_SLEEP;
790 error = vfs_lock_file(file->f_file, F_SETLK, &lock->fl, NULL);
791 lock->fl.fl_flags &= ~FL_SLEEP;
792
793 switch (error) {
794 case 0:
795 break;
796 case FILE_LOCK_DEFERRED:
797 dprintk("lockd: lock still blocked error %d\n", error);
798 nlmsvc_insert_block(block, NLM_NEVER);
799 nlmsvc_release_block(block);
800 return;
801 default:
802 printk(KERN_WARNING "lockd: unexpected error %d in %s!\n",
803 -error, __func__);
804 nlmsvc_insert_block(block, 10 * HZ);
805 nlmsvc_release_block(block);
806 return;
807 }
808
809callback:
810 /* Lock was granted by VFS. */
811 dprintk("lockd: GRANTing blocked lock.\n");
812 block->b_granted = 1;
813
814 /* keep block on the list, but don't reattempt until the RPC
815 * completes or the submission fails
816 */
817 nlmsvc_insert_block(block, NLM_NEVER);
818
819 /* Call the client -- use a soft RPC task since nlmsvc_retry_blocked
820 * will queue up a new one if this one times out
821 */
822 error = nlm_async_call(block->b_call, NLMPROC_GRANTED_MSG,
823 &nlmsvc_grant_ops);
824
825 /* RPC submission failed, wait a bit and retry */
826 if (error < 0)
827 nlmsvc_insert_block(block, 10 * HZ);
828}
829
830/*
831 * This is the callback from the RPC layer when the NLM_GRANTED_MSG
832 * RPC call has succeeded or timed out.
833 * Like all RPC callbacks, it is invoked by the rpciod process, so it
834 * better not sleep. Therefore, we put the blocked lock on the nlm_blocked
835 * chain once more in order to have it removed by lockd itself (which can
836 * then sleep on the file semaphore without disrupting e.g. the nfs client).
837 */
838static void nlmsvc_grant_callback(struct rpc_task *task, void *data)
839{
840 struct nlm_rqst *call = data;
841 struct nlm_block *block = call->a_block;
842 unsigned long timeout;
843
844 dprintk("lockd: GRANT_MSG RPC callback\n");
845
846 spin_lock(&nlm_blocked_lock);
847 /* if the block is not on a list at this point then it has
848 * been invalidated. Don't try to requeue it.
849 *
850 * FIXME: it's possible that the block is removed from the list
851 * after this check but before the nlmsvc_insert_block. In that
852 * case it will be added back. Perhaps we need better locking
853 * for nlm_blocked?
854 */
855 if (list_empty(&block->b_list))
856 goto out;
857
858 /* Technically, we should down the file semaphore here. Since we
859 * move the block towards the head of the queue only, no harm
860 * can be done, though. */
861 if (task->tk_status < 0) {
862 /* RPC error: Re-insert for retransmission */
863 timeout = 10 * HZ;
864 } else {
865 /* Call was successful, now wait for client callback */
866 timeout = 60 * HZ;
867 }
868 nlmsvc_insert_block_locked(block, timeout);
869 svc_wake_up(block->b_daemon);
870out:
871 spin_unlock(&nlm_blocked_lock);
872}
873
874/*
875 * FIXME: nlmsvc_release_block() grabs a mutex. This is not allowed for an
876 * .rpc_release rpc_call_op
877 */
878static void nlmsvc_grant_release(void *data)
879{
880 struct nlm_rqst *call = data;
881 nlmsvc_release_block(call->a_block);
882}
883
884static const struct rpc_call_ops nlmsvc_grant_ops = {
885 .rpc_call_done = nlmsvc_grant_callback,
886 .rpc_release = nlmsvc_grant_release,
887};
888
889/*
890 * We received a GRANT_RES callback. Try to find the corresponding
891 * block.
892 */
893void
894nlmsvc_grant_reply(struct nlm_cookie *cookie, __be32 status)
895{
896 struct nlm_block *block;
897
898 dprintk("grant_reply: looking for cookie %x, s=%d \n",
899 *(unsigned int *)(cookie->data), status);
900 if (!(block = nlmsvc_find_block(cookie)))
901 return;
902
903 if (block) {
904 if (status == nlm_lck_denied_grace_period) {
905 /* Try again in a couple of seconds */
906 nlmsvc_insert_block(block, 10 * HZ);
907 } else {
908 /* Lock is now held by client, or has been rejected.
909 * In both cases, the block should be removed. */
910 nlmsvc_unlink_block(block);
911 }
912 }
913 nlmsvc_release_block(block);
914}
915
916/* Helper function to handle retry of a deferred block.
917 * If it is a blocking lock, call grant_blocked.
918 * For a non-blocking lock or test lock, revisit the request.
919 */
920static void
921retry_deferred_block(struct nlm_block *block)
922{
923 if (!(block->b_flags & B_GOT_CALLBACK))
924 block->b_flags |= B_TIMED_OUT;
925 nlmsvc_insert_block(block, NLM_TIMEOUT);
926 dprintk("revisit block %p flags %d\n", block, block->b_flags);
927 if (block->b_deferred_req) {
928 block->b_deferred_req->revisit(block->b_deferred_req, 0);
929 block->b_deferred_req = NULL;
930 }
931}
932
933/*
934 * Retry all blocked locks that have been notified. This is where lockd
935 * picks up locks that can be granted, or grant notifications that must
936 * be retransmitted.
937 */
938unsigned long
939nlmsvc_retry_blocked(void)
940{
941 unsigned long timeout = MAX_SCHEDULE_TIMEOUT;
942 struct nlm_block *block;
943
944 while (!list_empty(&nlm_blocked) && !kthread_should_stop()) {
945 block = list_entry(nlm_blocked.next, struct nlm_block, b_list);
946
947 if (block->b_when == NLM_NEVER)
948 break;
949 if (time_after(block->b_when, jiffies)) {
950 timeout = block->b_when - jiffies;
951 break;
952 }
953
954 dprintk("nlmsvc_retry_blocked(%p, when=%ld)\n",
955 block, block->b_when);
956 if (block->b_flags & B_QUEUED) {
957 dprintk("nlmsvc_retry_blocked delete block (%p, granted=%d, flags=%d)\n",
958 block, block->b_granted, block->b_flags);
959 retry_deferred_block(block);
960 } else
961 nlmsvc_grant_blocked(block);
962 }
963
964 return timeout;
965}