Loading...
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#include <linux/exportfs.h>
35
36#define NLMDBG_FACILITY NLMDBG_SVCLOCK
37
38#ifdef CONFIG_LOCKD_V4
39#define nlm_deadlock nlm4_deadlock
40#else
41#define nlm_deadlock nlm_lck_denied
42#endif
43
44static void nlmsvc_release_block(struct nlm_block *block);
45static void nlmsvc_insert_block(struct nlm_block *block, unsigned long);
46static void nlmsvc_remove_block(struct nlm_block *block);
47
48static int nlmsvc_setgrantargs(struct nlm_rqst *call, struct nlm_lock *lock);
49static void nlmsvc_freegrantargs(struct nlm_rqst *call);
50static const struct rpc_call_ops nlmsvc_grant_ops;
51
52/*
53 * The list of blocked locks to retry
54 */
55static LIST_HEAD(nlm_blocked);
56static DEFINE_SPINLOCK(nlm_blocked_lock);
57
58#if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
59static const char *nlmdbg_cookie2a(const struct nlm_cookie *cookie)
60{
61 /*
62 * We can get away with a static buffer because this is only called
63 * from lockd, which is single-threaded.
64 */
65 static char buf[2*NLM_MAXCOOKIELEN+1];
66 unsigned int i, len = sizeof(buf);
67 char *p = buf;
68
69 len--; /* allow for trailing \0 */
70 if (len < 3)
71 return "???";
72 for (i = 0 ; i < cookie->len ; i++) {
73 if (len < 2) {
74 strcpy(p-3, "...");
75 break;
76 }
77 sprintf(p, "%02x", cookie->data[i]);
78 p += 2;
79 len -= 2;
80 }
81 *p = '\0';
82
83 return buf;
84}
85#endif
86
87/*
88 * Insert a blocked lock into the global list
89 */
90static void
91nlmsvc_insert_block_locked(struct nlm_block *block, unsigned long when)
92{
93 struct nlm_block *b;
94 struct list_head *pos;
95
96 dprintk("lockd: nlmsvc_insert_block(%p, %ld)\n", block, when);
97 if (list_empty(&block->b_list)) {
98 kref_get(&block->b_count);
99 } else {
100 list_del_init(&block->b_list);
101 }
102
103 pos = &nlm_blocked;
104 if (when != NLM_NEVER) {
105 if ((when += jiffies) == NLM_NEVER)
106 when ++;
107 list_for_each(pos, &nlm_blocked) {
108 b = list_entry(pos, struct nlm_block, b_list);
109 if (time_after(b->b_when,when) || b->b_when == NLM_NEVER)
110 break;
111 }
112 /* On normal exit from the loop, pos == &nlm_blocked,
113 * so we will be adding to the end of the list - good
114 */
115 }
116
117 list_add_tail(&block->b_list, pos);
118 block->b_when = when;
119}
120
121static void nlmsvc_insert_block(struct nlm_block *block, unsigned long when)
122{
123 spin_lock(&nlm_blocked_lock);
124 nlmsvc_insert_block_locked(block, when);
125 spin_unlock(&nlm_blocked_lock);
126}
127
128/*
129 * Remove a block from the global list
130 */
131static inline void
132nlmsvc_remove_block(struct nlm_block *block)
133{
134 if (!list_empty(&block->b_list)) {
135 spin_lock(&nlm_blocked_lock);
136 list_del_init(&block->b_list);
137 spin_unlock(&nlm_blocked_lock);
138 nlmsvc_release_block(block);
139 }
140}
141
142/*
143 * Find a block for a given lock
144 */
145static struct nlm_block *
146nlmsvc_lookup_block(struct nlm_file *file, struct nlm_lock *lock)
147{
148 struct nlm_block *block;
149 struct file_lock *fl;
150
151 dprintk("lockd: nlmsvc_lookup_block f=%p pd=%d %Ld-%Ld ty=%d\n",
152 file, lock->fl.fl_pid,
153 (long long)lock->fl.fl_start,
154 (long long)lock->fl.fl_end, lock->fl.fl_type);
155 list_for_each_entry(block, &nlm_blocked, b_list) {
156 fl = &block->b_call->a_args.lock.fl;
157 dprintk("lockd: check f=%p pd=%d %Ld-%Ld ty=%d cookie=%s\n",
158 block->b_file, fl->fl_pid,
159 (long long)fl->fl_start,
160 (long long)fl->fl_end, fl->fl_type,
161 nlmdbg_cookie2a(&block->b_call->a_args.cookie));
162 if (block->b_file == file && nlm_compare_locks(fl, &lock->fl)) {
163 kref_get(&block->b_count);
164 return block;
165 }
166 }
167
168 return NULL;
169}
170
171static inline int nlm_cookie_match(struct nlm_cookie *a, struct nlm_cookie *b)
172{
173 if (a->len != b->len)
174 return 0;
175 if (memcmp(a->data, b->data, a->len))
176 return 0;
177 return 1;
178}
179
180/*
181 * Find a block with a given NLM cookie.
182 */
183static inline struct nlm_block *
184nlmsvc_find_block(struct nlm_cookie *cookie)
185{
186 struct nlm_block *block;
187
188 list_for_each_entry(block, &nlm_blocked, b_list) {
189 if (nlm_cookie_match(&block->b_call->a_args.cookie,cookie))
190 goto found;
191 }
192
193 return NULL;
194
195found:
196 dprintk("nlmsvc_find_block(%s): block=%p\n", nlmdbg_cookie2a(cookie), block);
197 kref_get(&block->b_count);
198 return block;
199}
200
201/*
202 * Create a block and initialize it.
203 *
204 * Note: we explicitly set the cookie of the grant reply to that of
205 * the blocked lock request. The spec explicitly mentions that the client
206 * should _not_ rely on the callback containing the same cookie as the
207 * request, but (as I found out later) that's because some implementations
208 * do just this. Never mind the standards comittees, they support our
209 * logging industries.
210 *
211 * 10 years later: I hope we can safely ignore these old and broken
212 * clients by now. Let's fix this so we can uniquely identify an incoming
213 * GRANTED_RES message by cookie, without having to rely on the client's IP
214 * address. --okir
215 */
216static struct nlm_block *
217nlmsvc_create_block(struct svc_rqst *rqstp, struct nlm_host *host,
218 struct nlm_file *file, struct nlm_lock *lock,
219 struct nlm_cookie *cookie)
220{
221 struct nlm_block *block;
222 struct nlm_rqst *call = NULL;
223
224 call = nlm_alloc_call(host);
225 if (call == NULL)
226 return NULL;
227
228 /* Allocate memory for block, and initialize arguments */
229 block = kzalloc(sizeof(*block), GFP_KERNEL);
230 if (block == NULL)
231 goto failed;
232 kref_init(&block->b_count);
233 INIT_LIST_HEAD(&block->b_list);
234 INIT_LIST_HEAD(&block->b_flist);
235
236 if (!nlmsvc_setgrantargs(call, lock))
237 goto failed_free;
238
239 /* Set notifier function for VFS, and init args */
240 call->a_args.lock.fl.fl_flags |= FL_SLEEP;
241 call->a_args.lock.fl.fl_lmops = &nlmsvc_lock_operations;
242 nlmclnt_next_cookie(&call->a_args.cookie);
243
244 dprintk("lockd: created block %p...\n", block);
245
246 /* Create and initialize the block */
247 block->b_daemon = rqstp->rq_server;
248 block->b_host = host;
249 block->b_file = file;
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 = locks_delete_block(&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 list_del_init(&block->b_flist);
294 mutex_unlock(&file->f_mutex);
295
296 nlmsvc_freegrantargs(block->b_call);
297 nlmsvc_release_call(block->b_call);
298 nlm_release_file(block->b_file);
299 kfree(block);
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
336static struct nlm_lockowner *
337nlmsvc_get_lockowner(struct nlm_lockowner *lockowner)
338{
339 refcount_inc(&lockowner->count);
340 return lockowner;
341}
342
343void nlmsvc_put_lockowner(struct nlm_lockowner *lockowner)
344{
345 if (!refcount_dec_and_lock(&lockowner->count, &lockowner->host->h_lock))
346 return;
347 list_del(&lockowner->list);
348 spin_unlock(&lockowner->host->h_lock);
349 nlmsvc_release_host(lockowner->host);
350 kfree(lockowner);
351}
352
353static struct nlm_lockowner *__nlmsvc_find_lockowner(struct nlm_host *host, pid_t pid)
354{
355 struct nlm_lockowner *lockowner;
356 list_for_each_entry(lockowner, &host->h_lockowners, list) {
357 if (lockowner->pid != pid)
358 continue;
359 return nlmsvc_get_lockowner(lockowner);
360 }
361 return NULL;
362}
363
364static struct nlm_lockowner *nlmsvc_find_lockowner(struct nlm_host *host, pid_t pid)
365{
366 struct nlm_lockowner *res, *new = NULL;
367
368 spin_lock(&host->h_lock);
369 res = __nlmsvc_find_lockowner(host, pid);
370
371 if (res == NULL) {
372 spin_unlock(&host->h_lock);
373 new = kmalloc(sizeof(*res), GFP_KERNEL);
374 spin_lock(&host->h_lock);
375 res = __nlmsvc_find_lockowner(host, pid);
376 if (res == NULL && new != NULL) {
377 res = new;
378 /* fs/locks.c will manage the refcount through lock_ops */
379 refcount_set(&new->count, 1);
380 new->pid = pid;
381 new->host = nlm_get_host(host);
382 list_add(&new->list, &host->h_lockowners);
383 new = NULL;
384 }
385 }
386
387 spin_unlock(&host->h_lock);
388 kfree(new);
389 return res;
390}
391
392void
393nlmsvc_release_lockowner(struct nlm_lock *lock)
394{
395 if (lock->fl.fl_owner)
396 nlmsvc_put_lockowner(lock->fl.fl_owner);
397}
398
399void nlmsvc_locks_init_private(struct file_lock *fl, struct nlm_host *host,
400 pid_t pid)
401{
402 fl->fl_owner = nlmsvc_find_lockowner(host, pid);
403}
404
405/*
406 * Initialize arguments for GRANTED call. The nlm_rqst structure
407 * has been cleared already.
408 */
409static int nlmsvc_setgrantargs(struct nlm_rqst *call, struct nlm_lock *lock)
410{
411 locks_copy_lock(&call->a_args.lock.fl, &lock->fl);
412 memcpy(&call->a_args.lock.fh, &lock->fh, sizeof(call->a_args.lock.fh));
413 call->a_args.lock.caller = utsname()->nodename;
414 call->a_args.lock.oh.len = lock->oh.len;
415
416 /* set default data area */
417 call->a_args.lock.oh.data = call->a_owner;
418 call->a_args.lock.svid = ((struct nlm_lockowner *)lock->fl.fl_owner)->pid;
419
420 if (lock->oh.len > NLMCLNT_OHSIZE) {
421 void *data = kmalloc(lock->oh.len, GFP_KERNEL);
422 if (!data)
423 return 0;
424 call->a_args.lock.oh.data = (u8 *) data;
425 }
426
427 memcpy(call->a_args.lock.oh.data, lock->oh.data, lock->oh.len);
428 return 1;
429}
430
431static void nlmsvc_freegrantargs(struct nlm_rqst *call)
432{
433 if (call->a_args.lock.oh.data != call->a_owner)
434 kfree(call->a_args.lock.oh.data);
435
436 locks_release_private(&call->a_args.lock.fl);
437}
438
439/*
440 * Deferred lock request handling for non-blocking lock
441 */
442static __be32
443nlmsvc_defer_lock_rqst(struct svc_rqst *rqstp, struct nlm_block *block)
444{
445 __be32 status = nlm_lck_denied_nolocks;
446
447 block->b_flags |= B_QUEUED;
448
449 nlmsvc_insert_block(block, NLM_TIMEOUT);
450
451 block->b_cache_req = &rqstp->rq_chandle;
452 if (rqstp->rq_chandle.defer) {
453 block->b_deferred_req =
454 rqstp->rq_chandle.defer(block->b_cache_req);
455 if (block->b_deferred_req != NULL)
456 status = nlm_drop_reply;
457 }
458 dprintk("lockd: nlmsvc_defer_lock_rqst block %p flags %d status %d\n",
459 block, block->b_flags, ntohl(status));
460
461 return status;
462}
463
464/*
465 * Attempt to establish a lock, and if it can't be granted, block it
466 * if required.
467 */
468__be32
469nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file,
470 struct nlm_host *host, struct nlm_lock *lock, int wait,
471 struct nlm_cookie *cookie, int reclaim)
472{
473#if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
474 struct inode *inode = nlmsvc_file_inode(file);
475#endif
476 struct nlm_block *block = NULL;
477 int error;
478 int mode;
479 int async_block = 0;
480 __be32 ret;
481
482 dprintk("lockd: nlmsvc_lock(%s/%ld, ty=%d, pi=%d, %Ld-%Ld, bl=%d)\n",
483 inode->i_sb->s_id, inode->i_ino,
484 lock->fl.fl_type, lock->fl.fl_pid,
485 (long long)lock->fl.fl_start,
486 (long long)lock->fl.fl_end,
487 wait);
488
489 if (nlmsvc_file_file(file)->f_op->lock) {
490 async_block = wait;
491 wait = 0;
492 }
493
494 /* Lock file against concurrent access */
495 mutex_lock(&file->f_mutex);
496 /* Get existing block (in case client is busy-waiting)
497 * or create new block
498 */
499 block = nlmsvc_lookup_block(file, lock);
500 if (block == NULL) {
501 block = nlmsvc_create_block(rqstp, host, file, lock, cookie);
502 ret = nlm_lck_denied_nolocks;
503 if (block == NULL)
504 goto out;
505 lock = &block->b_call->a_args.lock;
506 } else
507 lock->fl.fl_flags &= ~FL_SLEEP;
508
509 if (block->b_flags & B_QUEUED) {
510 dprintk("lockd: nlmsvc_lock deferred block %p flags %d\n",
511 block, block->b_flags);
512 if (block->b_granted) {
513 nlmsvc_unlink_block(block);
514 ret = nlm_granted;
515 goto out;
516 }
517 if (block->b_flags & B_TIMED_OUT) {
518 nlmsvc_unlink_block(block);
519 ret = nlm_lck_denied;
520 goto out;
521 }
522 ret = nlm_drop_reply;
523 goto out;
524 }
525
526 if (locks_in_grace(SVC_NET(rqstp)) && !reclaim) {
527 ret = nlm_lck_denied_grace_period;
528 goto out;
529 }
530 if (reclaim && !locks_in_grace(SVC_NET(rqstp))) {
531 ret = nlm_lck_denied_grace_period;
532 goto out;
533 }
534
535 if (!wait)
536 lock->fl.fl_flags &= ~FL_SLEEP;
537 mode = lock_to_openmode(&lock->fl);
538 error = vfs_lock_file(file->f_file[mode], F_SETLK, &lock->fl, NULL);
539 lock->fl.fl_flags &= ~FL_SLEEP;
540
541 dprintk("lockd: vfs_lock_file returned %d\n", error);
542 switch (error) {
543 case 0:
544 ret = nlm_granted;
545 goto out;
546 case -EAGAIN:
547 /*
548 * If this is a blocking request for an
549 * already pending lock request then we need
550 * to put it back on lockd's block list
551 */
552 if (wait)
553 break;
554 ret = async_block ? nlm_lck_blocked : nlm_lck_denied;
555 goto out;
556 case FILE_LOCK_DEFERRED:
557 if (wait)
558 break;
559 /* Filesystem lock operation is in progress
560 Add it to the queue waiting for callback */
561 ret = nlmsvc_defer_lock_rqst(rqstp, block);
562 goto out;
563 case -EDEADLK:
564 ret = nlm_deadlock;
565 goto out;
566 default: /* includes ENOLCK */
567 ret = nlm_lck_denied_nolocks;
568 goto out;
569 }
570
571 ret = nlm_lck_blocked;
572
573 /* Append to list of blocked */
574 nlmsvc_insert_block(block, NLM_NEVER);
575out:
576 mutex_unlock(&file->f_mutex);
577 nlmsvc_release_block(block);
578 dprintk("lockd: nlmsvc_lock returned %u\n", ret);
579 return ret;
580}
581
582/*
583 * Test for presence of a conflicting lock.
584 */
585__be32
586nlmsvc_testlock(struct svc_rqst *rqstp, struct nlm_file *file,
587 struct nlm_host *host, struct nlm_lock *lock,
588 struct nlm_lock *conflock, struct nlm_cookie *cookie)
589{
590 int error;
591 int mode;
592 __be32 ret;
593
594 dprintk("lockd: nlmsvc_testlock(%s/%ld, ty=%d, %Ld-%Ld)\n",
595 nlmsvc_file_inode(file)->i_sb->s_id,
596 nlmsvc_file_inode(file)->i_ino,
597 lock->fl.fl_type,
598 (long long)lock->fl.fl_start,
599 (long long)lock->fl.fl_end);
600
601 if (locks_in_grace(SVC_NET(rqstp))) {
602 ret = nlm_lck_denied_grace_period;
603 goto out;
604 }
605
606 mode = lock_to_openmode(&lock->fl);
607 error = vfs_test_lock(file->f_file[mode], &lock->fl);
608 if (error) {
609 /* We can't currently deal with deferred test requests */
610 if (error == FILE_LOCK_DEFERRED)
611 WARN_ON_ONCE(1);
612
613 ret = nlm_lck_denied_nolocks;
614 goto out;
615 }
616
617 if (lock->fl.fl_type == F_UNLCK) {
618 ret = nlm_granted;
619 goto out;
620 }
621
622 dprintk("lockd: conflicting lock(ty=%d, %Ld-%Ld)\n",
623 lock->fl.fl_type, (long long)lock->fl.fl_start,
624 (long long)lock->fl.fl_end);
625 conflock->caller = "somehost"; /* FIXME */
626 conflock->len = strlen(conflock->caller);
627 conflock->oh.len = 0; /* don't return OH info */
628 conflock->svid = lock->fl.fl_pid;
629 conflock->fl.fl_type = lock->fl.fl_type;
630 conflock->fl.fl_start = lock->fl.fl_start;
631 conflock->fl.fl_end = lock->fl.fl_end;
632 locks_release_private(&lock->fl);
633
634 ret = nlm_lck_denied;
635out:
636 return ret;
637}
638
639/*
640 * Remove a lock.
641 * This implies a CANCEL call: We send a GRANT_MSG, the client replies
642 * with a GRANT_RES call which gets lost, and calls UNLOCK immediately
643 * afterwards. In this case the block will still be there, and hence
644 * must be removed.
645 */
646__be32
647nlmsvc_unlock(struct net *net, struct nlm_file *file, struct nlm_lock *lock)
648{
649 int error = 0;
650
651 dprintk("lockd: nlmsvc_unlock(%s/%ld, pi=%d, %Ld-%Ld)\n",
652 nlmsvc_file_inode(file)->i_sb->s_id,
653 nlmsvc_file_inode(file)->i_ino,
654 lock->fl.fl_pid,
655 (long long)lock->fl.fl_start,
656 (long long)lock->fl.fl_end);
657
658 /* First, cancel any lock that might be there */
659 nlmsvc_cancel_blocked(net, file, lock);
660
661 lock->fl.fl_type = F_UNLCK;
662 lock->fl.fl_file = file->f_file[O_RDONLY];
663 if (lock->fl.fl_file)
664 error = vfs_lock_file(lock->fl.fl_file, F_SETLK,
665 &lock->fl, NULL);
666 lock->fl.fl_file = file->f_file[O_WRONLY];
667 if (lock->fl.fl_file)
668 error |= vfs_lock_file(lock->fl.fl_file, F_SETLK,
669 &lock->fl, NULL);
670
671 return (error < 0)? nlm_lck_denied_nolocks : nlm_granted;
672}
673
674/*
675 * Cancel a previously blocked request.
676 *
677 * A cancel request always overrides any grant that may currently
678 * be in progress.
679 * The calling procedure must check whether the file can be closed.
680 */
681__be32
682nlmsvc_cancel_blocked(struct net *net, struct nlm_file *file, struct nlm_lock *lock)
683{
684 struct nlm_block *block;
685 int status = 0;
686 int mode;
687
688 dprintk("lockd: nlmsvc_cancel(%s/%ld, pi=%d, %Ld-%Ld)\n",
689 nlmsvc_file_inode(file)->i_sb->s_id,
690 nlmsvc_file_inode(file)->i_ino,
691 lock->fl.fl_pid,
692 (long long)lock->fl.fl_start,
693 (long long)lock->fl.fl_end);
694
695 if (locks_in_grace(net))
696 return nlm_lck_denied_grace_period;
697
698 mutex_lock(&file->f_mutex);
699 block = nlmsvc_lookup_block(file, lock);
700 mutex_unlock(&file->f_mutex);
701 if (block != NULL) {
702 struct file_lock *fl = &block->b_call->a_args.lock.fl;
703
704 mode = lock_to_openmode(fl);
705 vfs_cancel_lock(block->b_file->f_file[mode], fl);
706 status = nlmsvc_unlink_block(block);
707 nlmsvc_release_block(block);
708 }
709 return status ? nlm_lck_denied : nlm_granted;
710}
711
712/*
713 * This is a callback from the filesystem for VFS file lock requests.
714 * It will be used if lm_grant is defined and the filesystem can not
715 * respond to the request immediately.
716 * For SETLK or SETLKW request it will get the local posix lock.
717 * In all cases it will move the block to the head of nlm_blocked q where
718 * nlmsvc_retry_blocked() can send back a reply for SETLKW or revisit the
719 * deferred rpc for GETLK and SETLK.
720 */
721static void
722nlmsvc_update_deferred_block(struct nlm_block *block, int result)
723{
724 block->b_flags |= B_GOT_CALLBACK;
725 if (result == 0)
726 block->b_granted = 1;
727 else
728 block->b_flags |= B_TIMED_OUT;
729}
730
731static int nlmsvc_grant_deferred(struct file_lock *fl, int result)
732{
733 struct nlm_block *block;
734 int rc = -ENOENT;
735
736 spin_lock(&nlm_blocked_lock);
737 list_for_each_entry(block, &nlm_blocked, b_list) {
738 if (nlm_compare_locks(&block->b_call->a_args.lock.fl, fl)) {
739 dprintk("lockd: nlmsvc_notify_blocked block %p flags %d\n",
740 block, block->b_flags);
741 if (block->b_flags & B_QUEUED) {
742 if (block->b_flags & B_TIMED_OUT) {
743 rc = -ENOLCK;
744 break;
745 }
746 nlmsvc_update_deferred_block(block, result);
747 } else if (result == 0)
748 block->b_granted = 1;
749
750 nlmsvc_insert_block_locked(block, 0);
751 svc_wake_up(block->b_daemon);
752 rc = 0;
753 break;
754 }
755 }
756 spin_unlock(&nlm_blocked_lock);
757 if (rc == -ENOENT)
758 printk(KERN_WARNING "lockd: grant for unknown block\n");
759 return rc;
760}
761
762/*
763 * Unblock a blocked lock request. This is a callback invoked from the
764 * VFS layer when a lock on which we blocked is removed.
765 *
766 * This function doesn't grant the blocked lock instantly, but rather moves
767 * the block to the head of nlm_blocked where it can be picked up by lockd.
768 */
769static void
770nlmsvc_notify_blocked(struct file_lock *fl)
771{
772 struct nlm_block *block;
773
774 dprintk("lockd: VFS unblock notification for block %p\n", fl);
775 spin_lock(&nlm_blocked_lock);
776 list_for_each_entry(block, &nlm_blocked, b_list) {
777 if (nlm_compare_locks(&block->b_call->a_args.lock.fl, fl)) {
778 nlmsvc_insert_block_locked(block, 0);
779 spin_unlock(&nlm_blocked_lock);
780 svc_wake_up(block->b_daemon);
781 return;
782 }
783 }
784 spin_unlock(&nlm_blocked_lock);
785 printk(KERN_WARNING "lockd: notification for unknown block!\n");
786}
787
788static fl_owner_t nlmsvc_get_owner(fl_owner_t owner)
789{
790 return nlmsvc_get_lockowner(owner);
791}
792
793static void nlmsvc_put_owner(fl_owner_t owner)
794{
795 nlmsvc_put_lockowner(owner);
796}
797
798const struct lock_manager_operations nlmsvc_lock_operations = {
799 .lm_notify = nlmsvc_notify_blocked,
800 .lm_grant = nlmsvc_grant_deferred,
801 .lm_get_owner = nlmsvc_get_owner,
802 .lm_put_owner = nlmsvc_put_owner,
803};
804
805/*
806 * Try to claim a lock that was previously blocked.
807 *
808 * Note that we use both the RPC_GRANTED_MSG call _and_ an async
809 * RPC thread when notifying the client. This seems like overkill...
810 * Here's why:
811 * - we don't want to use a synchronous RPC thread, otherwise
812 * we might find ourselves hanging on a dead portmapper.
813 * - Some lockd implementations (e.g. HP) don't react to
814 * RPC_GRANTED calls; they seem to insist on RPC_GRANTED_MSG calls.
815 */
816static void
817nlmsvc_grant_blocked(struct nlm_block *block)
818{
819 struct nlm_file *file = block->b_file;
820 struct nlm_lock *lock = &block->b_call->a_args.lock;
821 int mode;
822 int error;
823 loff_t fl_start, fl_end;
824
825 dprintk("lockd: grant blocked lock %p\n", block);
826
827 kref_get(&block->b_count);
828
829 /* Unlink block request from list */
830 nlmsvc_unlink_block(block);
831
832 /* If b_granted is true this means we've been here before.
833 * Just retry the grant callback, possibly refreshing the RPC
834 * binding */
835 if (block->b_granted) {
836 nlm_rebind_host(block->b_host);
837 goto callback;
838 }
839
840 /* Try the lock operation again */
841 /* vfs_lock_file() can mangle fl_start and fl_end, but we need
842 * them unchanged for the GRANT_MSG
843 */
844 lock->fl.fl_flags |= FL_SLEEP;
845 fl_start = lock->fl.fl_start;
846 fl_end = lock->fl.fl_end;
847 mode = lock_to_openmode(&lock->fl);
848 error = vfs_lock_file(file->f_file[mode], F_SETLK, &lock->fl, NULL);
849 lock->fl.fl_flags &= ~FL_SLEEP;
850 lock->fl.fl_start = fl_start;
851 lock->fl.fl_end = fl_end;
852
853 switch (error) {
854 case 0:
855 break;
856 case FILE_LOCK_DEFERRED:
857 dprintk("lockd: lock still blocked error %d\n", error);
858 nlmsvc_insert_block(block, NLM_NEVER);
859 nlmsvc_release_block(block);
860 return;
861 default:
862 printk(KERN_WARNING "lockd: unexpected error %d in %s!\n",
863 -error, __func__);
864 nlmsvc_insert_block(block, 10 * HZ);
865 nlmsvc_release_block(block);
866 return;
867 }
868
869callback:
870 /* Lock was granted by VFS. */
871 dprintk("lockd: GRANTing blocked lock.\n");
872 block->b_granted = 1;
873
874 /* keep block on the list, but don't reattempt until the RPC
875 * completes or the submission fails
876 */
877 nlmsvc_insert_block(block, NLM_NEVER);
878
879 /* Call the client -- use a soft RPC task since nlmsvc_retry_blocked
880 * will queue up a new one if this one times out
881 */
882 error = nlm_async_call(block->b_call, NLMPROC_GRANTED_MSG,
883 &nlmsvc_grant_ops);
884
885 /* RPC submission failed, wait a bit and retry */
886 if (error < 0)
887 nlmsvc_insert_block(block, 10 * HZ);
888}
889
890/*
891 * This is the callback from the RPC layer when the NLM_GRANTED_MSG
892 * RPC call has succeeded or timed out.
893 * Like all RPC callbacks, it is invoked by the rpciod process, so it
894 * better not sleep. Therefore, we put the blocked lock on the nlm_blocked
895 * chain once more in order to have it removed by lockd itself (which can
896 * then sleep on the file semaphore without disrupting e.g. the nfs client).
897 */
898static void nlmsvc_grant_callback(struct rpc_task *task, void *data)
899{
900 struct nlm_rqst *call = data;
901 struct nlm_block *block = call->a_block;
902 unsigned long timeout;
903
904 dprintk("lockd: GRANT_MSG RPC callback\n");
905
906 spin_lock(&nlm_blocked_lock);
907 /* if the block is not on a list at this point then it has
908 * been invalidated. Don't try to requeue it.
909 *
910 * FIXME: it's possible that the block is removed from the list
911 * after this check but before the nlmsvc_insert_block. In that
912 * case it will be added back. Perhaps we need better locking
913 * for nlm_blocked?
914 */
915 if (list_empty(&block->b_list))
916 goto out;
917
918 /* Technically, we should down the file semaphore here. Since we
919 * move the block towards the head of the queue only, no harm
920 * can be done, though. */
921 if (task->tk_status < 0) {
922 /* RPC error: Re-insert for retransmission */
923 timeout = 10 * HZ;
924 } else {
925 /* Call was successful, now wait for client callback */
926 timeout = 60 * HZ;
927 }
928 nlmsvc_insert_block_locked(block, timeout);
929 svc_wake_up(block->b_daemon);
930out:
931 spin_unlock(&nlm_blocked_lock);
932}
933
934/*
935 * FIXME: nlmsvc_release_block() grabs a mutex. This is not allowed for an
936 * .rpc_release rpc_call_op
937 */
938static void nlmsvc_grant_release(void *data)
939{
940 struct nlm_rqst *call = data;
941 nlmsvc_release_block(call->a_block);
942}
943
944static const struct rpc_call_ops nlmsvc_grant_ops = {
945 .rpc_call_done = nlmsvc_grant_callback,
946 .rpc_release = nlmsvc_grant_release,
947};
948
949/*
950 * We received a GRANT_RES callback. Try to find the corresponding
951 * block.
952 */
953void
954nlmsvc_grant_reply(struct nlm_cookie *cookie, __be32 status)
955{
956 struct nlm_block *block;
957
958 dprintk("grant_reply: looking for cookie %x, s=%d \n",
959 *(unsigned int *)(cookie->data), status);
960 if (!(block = nlmsvc_find_block(cookie)))
961 return;
962
963 if (status == nlm_lck_denied_grace_period) {
964 /* Try again in a couple of seconds */
965 nlmsvc_insert_block(block, 10 * HZ);
966 } else {
967 /*
968 * Lock is now held by client, or has been rejected.
969 * In both cases, the block should be removed.
970 */
971 nlmsvc_unlink_block(block);
972 }
973 nlmsvc_release_block(block);
974}
975
976/* Helper function to handle retry of a deferred block.
977 * If it is a blocking lock, call grant_blocked.
978 * For a non-blocking lock or test lock, revisit the request.
979 */
980static void
981retry_deferred_block(struct nlm_block *block)
982{
983 if (!(block->b_flags & B_GOT_CALLBACK))
984 block->b_flags |= B_TIMED_OUT;
985 nlmsvc_insert_block(block, NLM_TIMEOUT);
986 dprintk("revisit block %p flags %d\n", block, block->b_flags);
987 if (block->b_deferred_req) {
988 block->b_deferred_req->revisit(block->b_deferred_req, 0);
989 block->b_deferred_req = NULL;
990 }
991}
992
993/*
994 * Retry all blocked locks that have been notified. This is where lockd
995 * picks up locks that can be granted, or grant notifications that must
996 * be retransmitted.
997 */
998unsigned long
999nlmsvc_retry_blocked(void)
1000{
1001 unsigned long timeout = MAX_SCHEDULE_TIMEOUT;
1002 struct nlm_block *block;
1003
1004 spin_lock(&nlm_blocked_lock);
1005 while (!list_empty(&nlm_blocked) && !kthread_should_stop()) {
1006 block = list_entry(nlm_blocked.next, struct nlm_block, b_list);
1007
1008 if (block->b_when == NLM_NEVER)
1009 break;
1010 if (time_after(block->b_when, jiffies)) {
1011 timeout = block->b_when - jiffies;
1012 break;
1013 }
1014 spin_unlock(&nlm_blocked_lock);
1015
1016 dprintk("nlmsvc_retry_blocked(%p, when=%ld)\n",
1017 block, block->b_when);
1018 if (block->b_flags & B_QUEUED) {
1019 dprintk("nlmsvc_retry_blocked delete block (%p, granted=%d, flags=%d)\n",
1020 block, block->b_granted, block->b_flags);
1021 retry_deferred_block(block);
1022 } else
1023 nlmsvc_grant_blocked(block);
1024 spin_lock(&nlm_blocked_lock);
1025 }
1026 spin_unlock(&nlm_blocked_lock);
1027
1028 return timeout;
1029}
1/*
2 * linux/fs/lockd/svclock.c
3 *
4 * Handling of server-side locks, mostly of the blocked variety.
5 * This is the ugliest part of lockd because we tread on very thin ice.
6 * GRANT and CANCEL calls may get stuck, meet in mid-flight, etc.
7 * IMNSHO introducing the grant callback into the NLM protocol was one
8 * of the worst ideas Sun ever had. Except maybe for the idea of doing
9 * NFS file locking at all.
10 *
11 * I'm trying hard to avoid race conditions by protecting most accesses
12 * to a file's list of blocked locks through a semaphore. The global
13 * list of blocked locks is not protected in this fashion however.
14 * Therefore, some functions (such as the RPC callback for the async grant
15 * call) move blocked locks towards the head of the list *while some other
16 * process might be traversing it*. This should not be a problem in
17 * practice, because this will only cause functions traversing the list
18 * to visit some blocks twice.
19 *
20 * Copyright (C) 1996, Olaf Kirch <okir@monad.swb.de>
21 */
22
23#include <linux/types.h>
24#include <linux/slab.h>
25#include <linux/errno.h>
26#include <linux/kernel.h>
27#include <linux/sched.h>
28#include <linux/sunrpc/clnt.h>
29#include <linux/sunrpc/svc.h>
30#include <linux/lockd/nlm.h>
31#include <linux/lockd/lockd.h>
32#include <linux/kthread.h>
33
34#define NLMDBG_FACILITY NLMDBG_SVCLOCK
35
36#ifdef CONFIG_LOCKD_V4
37#define nlm_deadlock nlm4_deadlock
38#else
39#define nlm_deadlock nlm_lck_denied
40#endif
41
42static void nlmsvc_release_block(struct nlm_block *block);
43static void nlmsvc_insert_block(struct nlm_block *block, unsigned long);
44static void nlmsvc_remove_block(struct nlm_block *block);
45
46static int nlmsvc_setgrantargs(struct nlm_rqst *call, struct nlm_lock *lock);
47static void nlmsvc_freegrantargs(struct nlm_rqst *call);
48static const struct rpc_call_ops nlmsvc_grant_ops;
49static const char *nlmdbg_cookie2a(const struct nlm_cookie *cookie);
50
51/*
52 * The list of blocked locks to retry
53 */
54static LIST_HEAD(nlm_blocked);
55static DEFINE_SPINLOCK(nlm_blocked_lock);
56
57/*
58 * Insert a blocked lock into the global list
59 */
60static void
61nlmsvc_insert_block_locked(struct nlm_block *block, unsigned long when)
62{
63 struct nlm_block *b;
64 struct list_head *pos;
65
66 dprintk("lockd: nlmsvc_insert_block(%p, %ld)\n", block, when);
67 if (list_empty(&block->b_list)) {
68 kref_get(&block->b_count);
69 } else {
70 list_del_init(&block->b_list);
71 }
72
73 pos = &nlm_blocked;
74 if (when != NLM_NEVER) {
75 if ((when += jiffies) == NLM_NEVER)
76 when ++;
77 list_for_each(pos, &nlm_blocked) {
78 b = list_entry(pos, struct nlm_block, b_list);
79 if (time_after(b->b_when,when) || b->b_when == NLM_NEVER)
80 break;
81 }
82 /* On normal exit from the loop, pos == &nlm_blocked,
83 * so we will be adding to the end of the list - good
84 */
85 }
86
87 list_add_tail(&block->b_list, pos);
88 block->b_when = when;
89}
90
91static void nlmsvc_insert_block(struct nlm_block *block, unsigned long when)
92{
93 spin_lock(&nlm_blocked_lock);
94 nlmsvc_insert_block_locked(block, when);
95 spin_unlock(&nlm_blocked_lock);
96}
97
98/*
99 * Remove a block from the global list
100 */
101static inline void
102nlmsvc_remove_block(struct nlm_block *block)
103{
104 if (!list_empty(&block->b_list)) {
105 spin_lock(&nlm_blocked_lock);
106 list_del_init(&block->b_list);
107 spin_unlock(&nlm_blocked_lock);
108 nlmsvc_release_block(block);
109 }
110}
111
112/*
113 * Find a block for a given lock
114 */
115static struct nlm_block *
116nlmsvc_lookup_block(struct nlm_file *file, struct nlm_lock *lock)
117{
118 struct nlm_block *block;
119 struct file_lock *fl;
120
121 dprintk("lockd: nlmsvc_lookup_block f=%p pd=%d %Ld-%Ld ty=%d\n",
122 file, lock->fl.fl_pid,
123 (long long)lock->fl.fl_start,
124 (long long)lock->fl.fl_end, lock->fl.fl_type);
125 list_for_each_entry(block, &nlm_blocked, b_list) {
126 fl = &block->b_call->a_args.lock.fl;
127 dprintk("lockd: check f=%p pd=%d %Ld-%Ld ty=%d cookie=%s\n",
128 block->b_file, fl->fl_pid,
129 (long long)fl->fl_start,
130 (long long)fl->fl_end, fl->fl_type,
131 nlmdbg_cookie2a(&block->b_call->a_args.cookie));
132 if (block->b_file == file && nlm_compare_locks(fl, &lock->fl)) {
133 kref_get(&block->b_count);
134 return block;
135 }
136 }
137
138 return NULL;
139}
140
141static inline int nlm_cookie_match(struct nlm_cookie *a, struct nlm_cookie *b)
142{
143 if (a->len != b->len)
144 return 0;
145 if (memcmp(a->data, b->data, a->len))
146 return 0;
147 return 1;
148}
149
150/*
151 * Find a block with a given NLM cookie.
152 */
153static inline struct nlm_block *
154nlmsvc_find_block(struct nlm_cookie *cookie)
155{
156 struct nlm_block *block;
157
158 list_for_each_entry(block, &nlm_blocked, b_list) {
159 if (nlm_cookie_match(&block->b_call->a_args.cookie,cookie))
160 goto found;
161 }
162
163 return NULL;
164
165found:
166 dprintk("nlmsvc_find_block(%s): block=%p\n", nlmdbg_cookie2a(cookie), block);
167 kref_get(&block->b_count);
168 return block;
169}
170
171/*
172 * Create a block and initialize it.
173 *
174 * Note: we explicitly set the cookie of the grant reply to that of
175 * the blocked lock request. The spec explicitly mentions that the client
176 * should _not_ rely on the callback containing the same cookie as the
177 * request, but (as I found out later) that's because some implementations
178 * do just this. Never mind the standards comittees, they support our
179 * logging industries.
180 *
181 * 10 years later: I hope we can safely ignore these old and broken
182 * clients by now. Let's fix this so we can uniquely identify an incoming
183 * GRANTED_RES message by cookie, without having to rely on the client's IP
184 * address. --okir
185 */
186static struct nlm_block *
187nlmsvc_create_block(struct svc_rqst *rqstp, struct nlm_host *host,
188 struct nlm_file *file, struct nlm_lock *lock,
189 struct nlm_cookie *cookie)
190{
191 struct nlm_block *block;
192 struct nlm_rqst *call = NULL;
193
194 nlm_get_host(host);
195 call = nlm_alloc_call(host);
196 if (call == NULL)
197 return NULL;
198
199 /* Allocate memory for block, and initialize arguments */
200 block = kzalloc(sizeof(*block), GFP_KERNEL);
201 if (block == NULL)
202 goto failed;
203 kref_init(&block->b_count);
204 INIT_LIST_HEAD(&block->b_list);
205 INIT_LIST_HEAD(&block->b_flist);
206
207 if (!nlmsvc_setgrantargs(call, lock))
208 goto failed_free;
209
210 /* Set notifier function for VFS, and init args */
211 call->a_args.lock.fl.fl_flags |= FL_SLEEP;
212 call->a_args.lock.fl.fl_lmops = &nlmsvc_lock_operations;
213 nlmclnt_next_cookie(&call->a_args.cookie);
214
215 dprintk("lockd: created block %p...\n", block);
216
217 /* Create and initialize the block */
218 block->b_daemon = rqstp->rq_server;
219 block->b_host = host;
220 block->b_file = file;
221 block->b_fl = NULL;
222 file->f_count++;
223
224 /* Add to file's list of blocks */
225 list_add(&block->b_flist, &file->f_blocks);
226
227 /* Set up RPC arguments for callback */
228 block->b_call = call;
229 call->a_flags = RPC_TASK_ASYNC;
230 call->a_block = block;
231
232 return block;
233
234failed_free:
235 kfree(block);
236failed:
237 nlmsvc_release_call(call);
238 return NULL;
239}
240
241/*
242 * Delete a block.
243 * It is the caller's responsibility to check whether the file
244 * can be closed hereafter.
245 */
246static int nlmsvc_unlink_block(struct nlm_block *block)
247{
248 int status;
249 dprintk("lockd: unlinking block %p...\n", block);
250
251 /* Remove block from list */
252 status = posix_unblock_lock(block->b_file->f_file, &block->b_call->a_args.lock.fl);
253 nlmsvc_remove_block(block);
254 return status;
255}
256
257static void nlmsvc_free_block(struct kref *kref)
258{
259 struct nlm_block *block = container_of(kref, struct nlm_block, b_count);
260 struct nlm_file *file = block->b_file;
261
262 dprintk("lockd: freeing block %p...\n", block);
263
264 /* Remove block from file's list of blocks */
265 mutex_lock(&file->f_mutex);
266 list_del_init(&block->b_flist);
267 mutex_unlock(&file->f_mutex);
268
269 nlmsvc_freegrantargs(block->b_call);
270 nlmsvc_release_call(block->b_call);
271 nlm_release_file(block->b_file);
272 kfree(block->b_fl);
273 kfree(block);
274}
275
276static void nlmsvc_release_block(struct nlm_block *block)
277{
278 if (block != NULL)
279 kref_put(&block->b_count, nlmsvc_free_block);
280}
281
282/*
283 * Loop over all blocks and delete blocks held by
284 * a matching host.
285 */
286void nlmsvc_traverse_blocks(struct nlm_host *host,
287 struct nlm_file *file,
288 nlm_host_match_fn_t match)
289{
290 struct nlm_block *block, *next;
291
292restart:
293 mutex_lock(&file->f_mutex);
294 list_for_each_entry_safe(block, next, &file->f_blocks, b_flist) {
295 if (!match(block->b_host, host))
296 continue;
297 /* Do not destroy blocks that are not on
298 * the global retry list - why? */
299 if (list_empty(&block->b_list))
300 continue;
301 kref_get(&block->b_count);
302 mutex_unlock(&file->f_mutex);
303 nlmsvc_unlink_block(block);
304 nlmsvc_release_block(block);
305 goto restart;
306 }
307 mutex_unlock(&file->f_mutex);
308}
309
310/*
311 * Initialize arguments for GRANTED call. The nlm_rqst structure
312 * has been cleared already.
313 */
314static int nlmsvc_setgrantargs(struct nlm_rqst *call, struct nlm_lock *lock)
315{
316 locks_copy_lock(&call->a_args.lock.fl, &lock->fl);
317 memcpy(&call->a_args.lock.fh, &lock->fh, sizeof(call->a_args.lock.fh));
318 call->a_args.lock.caller = utsname()->nodename;
319 call->a_args.lock.oh.len = lock->oh.len;
320
321 /* set default data area */
322 call->a_args.lock.oh.data = call->a_owner;
323 call->a_args.lock.svid = lock->fl.fl_pid;
324
325 if (lock->oh.len > NLMCLNT_OHSIZE) {
326 void *data = kmalloc(lock->oh.len, GFP_KERNEL);
327 if (!data)
328 return 0;
329 call->a_args.lock.oh.data = (u8 *) data;
330 }
331
332 memcpy(call->a_args.lock.oh.data, lock->oh.data, lock->oh.len);
333 return 1;
334}
335
336static void nlmsvc_freegrantargs(struct nlm_rqst *call)
337{
338 if (call->a_args.lock.oh.data != call->a_owner)
339 kfree(call->a_args.lock.oh.data);
340
341 locks_release_private(&call->a_args.lock.fl);
342}
343
344/*
345 * Deferred lock request handling for non-blocking lock
346 */
347static __be32
348nlmsvc_defer_lock_rqst(struct svc_rqst *rqstp, struct nlm_block *block)
349{
350 __be32 status = nlm_lck_denied_nolocks;
351
352 block->b_flags |= B_QUEUED;
353
354 nlmsvc_insert_block(block, NLM_TIMEOUT);
355
356 block->b_cache_req = &rqstp->rq_chandle;
357 if (rqstp->rq_chandle.defer) {
358 block->b_deferred_req =
359 rqstp->rq_chandle.defer(block->b_cache_req);
360 if (block->b_deferred_req != NULL)
361 status = nlm_drop_reply;
362 }
363 dprintk("lockd: nlmsvc_defer_lock_rqst block %p flags %d status %d\n",
364 block, block->b_flags, ntohl(status));
365
366 return status;
367}
368
369/*
370 * Attempt to establish a lock, and if it can't be granted, block it
371 * if required.
372 */
373__be32
374nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file,
375 struct nlm_host *host, struct nlm_lock *lock, int wait,
376 struct nlm_cookie *cookie, int reclaim)
377{
378 struct nlm_block *block = NULL;
379 int error;
380 __be32 ret;
381
382 dprintk("lockd: nlmsvc_lock(%s/%ld, ty=%d, pi=%d, %Ld-%Ld, bl=%d)\n",
383 file->f_file->f_path.dentry->d_inode->i_sb->s_id,
384 file->f_file->f_path.dentry->d_inode->i_ino,
385 lock->fl.fl_type, lock->fl.fl_pid,
386 (long long)lock->fl.fl_start,
387 (long long)lock->fl.fl_end,
388 wait);
389
390 /* Lock file against concurrent access */
391 mutex_lock(&file->f_mutex);
392 /* Get existing block (in case client is busy-waiting)
393 * or create new block
394 */
395 block = nlmsvc_lookup_block(file, lock);
396 if (block == NULL) {
397 block = nlmsvc_create_block(rqstp, host, file, lock, cookie);
398 ret = nlm_lck_denied_nolocks;
399 if (block == NULL)
400 goto out;
401 lock = &block->b_call->a_args.lock;
402 } else
403 lock->fl.fl_flags &= ~FL_SLEEP;
404
405 if (block->b_flags & B_QUEUED) {
406 dprintk("lockd: nlmsvc_lock deferred block %p flags %d\n",
407 block, block->b_flags);
408 if (block->b_granted) {
409 nlmsvc_unlink_block(block);
410 ret = nlm_granted;
411 goto out;
412 }
413 if (block->b_flags & B_TIMED_OUT) {
414 nlmsvc_unlink_block(block);
415 ret = nlm_lck_denied;
416 goto out;
417 }
418 ret = nlm_drop_reply;
419 goto out;
420 }
421
422 if (locks_in_grace() && !reclaim) {
423 ret = nlm_lck_denied_grace_period;
424 goto out;
425 }
426 if (reclaim && !locks_in_grace()) {
427 ret = nlm_lck_denied_grace_period;
428 goto out;
429 }
430
431 if (!wait)
432 lock->fl.fl_flags &= ~FL_SLEEP;
433 error = vfs_lock_file(file->f_file, F_SETLK, &lock->fl, NULL);
434 lock->fl.fl_flags &= ~FL_SLEEP;
435
436 dprintk("lockd: vfs_lock_file returned %d\n", error);
437 switch (error) {
438 case 0:
439 ret = nlm_granted;
440 goto out;
441 case -EAGAIN:
442 /*
443 * If this is a blocking request for an
444 * already pending lock request then we need
445 * to put it back on lockd's block list
446 */
447 if (wait)
448 break;
449 ret = nlm_lck_denied;
450 goto out;
451 case FILE_LOCK_DEFERRED:
452 if (wait)
453 break;
454 /* Filesystem lock operation is in progress
455 Add it to the queue waiting for callback */
456 ret = nlmsvc_defer_lock_rqst(rqstp, block);
457 goto out;
458 case -EDEADLK:
459 ret = nlm_deadlock;
460 goto out;
461 default: /* includes ENOLCK */
462 ret = nlm_lck_denied_nolocks;
463 goto out;
464 }
465
466 ret = nlm_lck_blocked;
467
468 /* Append to list of blocked */
469 nlmsvc_insert_block(block, NLM_NEVER);
470out:
471 mutex_unlock(&file->f_mutex);
472 nlmsvc_release_block(block);
473 dprintk("lockd: nlmsvc_lock returned %u\n", ret);
474 return ret;
475}
476
477/*
478 * Test for presence of a conflicting lock.
479 */
480__be32
481nlmsvc_testlock(struct svc_rqst *rqstp, struct nlm_file *file,
482 struct nlm_host *host, struct nlm_lock *lock,
483 struct nlm_lock *conflock, struct nlm_cookie *cookie)
484{
485 struct nlm_block *block = NULL;
486 int error;
487 __be32 ret;
488
489 dprintk("lockd: nlmsvc_testlock(%s/%ld, ty=%d, %Ld-%Ld)\n",
490 file->f_file->f_path.dentry->d_inode->i_sb->s_id,
491 file->f_file->f_path.dentry->d_inode->i_ino,
492 lock->fl.fl_type,
493 (long long)lock->fl.fl_start,
494 (long long)lock->fl.fl_end);
495
496 /* Get existing block (in case client is busy-waiting) */
497 block = nlmsvc_lookup_block(file, lock);
498
499 if (block == NULL) {
500 struct file_lock *conf = kzalloc(sizeof(*conf), GFP_KERNEL);
501
502 if (conf == NULL)
503 return nlm_granted;
504 block = nlmsvc_create_block(rqstp, host, file, lock, cookie);
505 if (block == NULL) {
506 kfree(conf);
507 return nlm_granted;
508 }
509 block->b_fl = conf;
510 }
511 if (block->b_flags & B_QUEUED) {
512 dprintk("lockd: nlmsvc_testlock deferred block %p flags %d fl %p\n",
513 block, block->b_flags, block->b_fl);
514 if (block->b_flags & B_TIMED_OUT) {
515 nlmsvc_unlink_block(block);
516 ret = nlm_lck_denied;
517 goto out;
518 }
519 if (block->b_flags & B_GOT_CALLBACK) {
520 nlmsvc_unlink_block(block);
521 if (block->b_fl != NULL
522 && block->b_fl->fl_type != F_UNLCK) {
523 lock->fl = *block->b_fl;
524 goto conf_lock;
525 } else {
526 ret = nlm_granted;
527 goto out;
528 }
529 }
530 ret = nlm_drop_reply;
531 goto out;
532 }
533
534 if (locks_in_grace()) {
535 ret = nlm_lck_denied_grace_period;
536 goto out;
537 }
538 error = vfs_test_lock(file->f_file, &lock->fl);
539 if (error == FILE_LOCK_DEFERRED) {
540 ret = nlmsvc_defer_lock_rqst(rqstp, block);
541 goto out;
542 }
543 if (error) {
544 ret = nlm_lck_denied_nolocks;
545 goto out;
546 }
547 if (lock->fl.fl_type == F_UNLCK) {
548 ret = nlm_granted;
549 goto out;
550 }
551
552conf_lock:
553 dprintk("lockd: conflicting lock(ty=%d, %Ld-%Ld)\n",
554 lock->fl.fl_type, (long long)lock->fl.fl_start,
555 (long long)lock->fl.fl_end);
556 conflock->caller = "somehost"; /* FIXME */
557 conflock->len = strlen(conflock->caller);
558 conflock->oh.len = 0; /* don't return OH info */
559 conflock->svid = lock->fl.fl_pid;
560 conflock->fl.fl_type = lock->fl.fl_type;
561 conflock->fl.fl_start = lock->fl.fl_start;
562 conflock->fl.fl_end = lock->fl.fl_end;
563 ret = nlm_lck_denied;
564out:
565 if (block)
566 nlmsvc_release_block(block);
567 return ret;
568}
569
570/*
571 * Remove a lock.
572 * This implies a CANCEL call: We send a GRANT_MSG, the client replies
573 * with a GRANT_RES call which gets lost, and calls UNLOCK immediately
574 * afterwards. In this case the block will still be there, and hence
575 * must be removed.
576 */
577__be32
578nlmsvc_unlock(struct nlm_file *file, struct nlm_lock *lock)
579{
580 int error;
581
582 dprintk("lockd: nlmsvc_unlock(%s/%ld, pi=%d, %Ld-%Ld)\n",
583 file->f_file->f_path.dentry->d_inode->i_sb->s_id,
584 file->f_file->f_path.dentry->d_inode->i_ino,
585 lock->fl.fl_pid,
586 (long long)lock->fl.fl_start,
587 (long long)lock->fl.fl_end);
588
589 /* First, cancel any lock that might be there */
590 nlmsvc_cancel_blocked(file, lock);
591
592 lock->fl.fl_type = F_UNLCK;
593 error = vfs_lock_file(file->f_file, F_SETLK, &lock->fl, NULL);
594
595 return (error < 0)? nlm_lck_denied_nolocks : nlm_granted;
596}
597
598/*
599 * Cancel a previously blocked request.
600 *
601 * A cancel request always overrides any grant that may currently
602 * be in progress.
603 * The calling procedure must check whether the file can be closed.
604 */
605__be32
606nlmsvc_cancel_blocked(struct nlm_file *file, struct nlm_lock *lock)
607{
608 struct nlm_block *block;
609 int status = 0;
610
611 dprintk("lockd: nlmsvc_cancel(%s/%ld, pi=%d, %Ld-%Ld)\n",
612 file->f_file->f_path.dentry->d_inode->i_sb->s_id,
613 file->f_file->f_path.dentry->d_inode->i_ino,
614 lock->fl.fl_pid,
615 (long long)lock->fl.fl_start,
616 (long long)lock->fl.fl_end);
617
618 if (locks_in_grace())
619 return nlm_lck_denied_grace_period;
620
621 mutex_lock(&file->f_mutex);
622 block = nlmsvc_lookup_block(file, lock);
623 mutex_unlock(&file->f_mutex);
624 if (block != NULL) {
625 vfs_cancel_lock(block->b_file->f_file,
626 &block->b_call->a_args.lock.fl);
627 status = nlmsvc_unlink_block(block);
628 nlmsvc_release_block(block);
629 }
630 return status ? nlm_lck_denied : nlm_granted;
631}
632
633/*
634 * This is a callback from the filesystem for VFS file lock requests.
635 * It will be used if lm_grant is defined and the filesystem can not
636 * respond to the request immediately.
637 * For GETLK request it will copy the reply to the nlm_block.
638 * For SETLK or SETLKW request it will get the local posix lock.
639 * In all cases it will move the block to the head of nlm_blocked q where
640 * nlmsvc_retry_blocked() can send back a reply for SETLKW or revisit the
641 * deferred rpc for GETLK and SETLK.
642 */
643static void
644nlmsvc_update_deferred_block(struct nlm_block *block, struct file_lock *conf,
645 int result)
646{
647 block->b_flags |= B_GOT_CALLBACK;
648 if (result == 0)
649 block->b_granted = 1;
650 else
651 block->b_flags |= B_TIMED_OUT;
652 if (conf) {
653 if (block->b_fl)
654 __locks_copy_lock(block->b_fl, conf);
655 }
656}
657
658static int nlmsvc_grant_deferred(struct file_lock *fl, struct file_lock *conf,
659 int result)
660{
661 struct nlm_block *block;
662 int rc = -ENOENT;
663
664 spin_lock(&nlm_blocked_lock);
665 list_for_each_entry(block, &nlm_blocked, b_list) {
666 if (nlm_compare_locks(&block->b_call->a_args.lock.fl, fl)) {
667 dprintk("lockd: nlmsvc_notify_blocked block %p flags %d\n",
668 block, block->b_flags);
669 if (block->b_flags & B_QUEUED) {
670 if (block->b_flags & B_TIMED_OUT) {
671 rc = -ENOLCK;
672 break;
673 }
674 nlmsvc_update_deferred_block(block, conf, result);
675 } else if (result == 0)
676 block->b_granted = 1;
677
678 nlmsvc_insert_block_locked(block, 0);
679 svc_wake_up(block->b_daemon);
680 rc = 0;
681 break;
682 }
683 }
684 spin_unlock(&nlm_blocked_lock);
685 if (rc == -ENOENT)
686 printk(KERN_WARNING "lockd: grant for unknown block\n");
687 return rc;
688}
689
690/*
691 * Unblock a blocked lock request. This is a callback invoked from the
692 * VFS layer when a lock on which we blocked is removed.
693 *
694 * This function doesn't grant the blocked lock instantly, but rather moves
695 * the block to the head of nlm_blocked where it can be picked up by lockd.
696 */
697static void
698nlmsvc_notify_blocked(struct file_lock *fl)
699{
700 struct nlm_block *block;
701
702 dprintk("lockd: VFS unblock notification for block %p\n", fl);
703 spin_lock(&nlm_blocked_lock);
704 list_for_each_entry(block, &nlm_blocked, b_list) {
705 if (nlm_compare_locks(&block->b_call->a_args.lock.fl, fl)) {
706 nlmsvc_insert_block_locked(block, 0);
707 spin_unlock(&nlm_blocked_lock);
708 svc_wake_up(block->b_daemon);
709 return;
710 }
711 }
712 spin_unlock(&nlm_blocked_lock);
713 printk(KERN_WARNING "lockd: notification for unknown block!\n");
714}
715
716static int nlmsvc_same_owner(struct file_lock *fl1, struct file_lock *fl2)
717{
718 return fl1->fl_owner == fl2->fl_owner && fl1->fl_pid == fl2->fl_pid;
719}
720
721const struct lock_manager_operations nlmsvc_lock_operations = {
722 .lm_compare_owner = nlmsvc_same_owner,
723 .lm_notify = nlmsvc_notify_blocked,
724 .lm_grant = nlmsvc_grant_deferred,
725};
726
727/*
728 * Try to claim a lock that was previously blocked.
729 *
730 * Note that we use both the RPC_GRANTED_MSG call _and_ an async
731 * RPC thread when notifying the client. This seems like overkill...
732 * Here's why:
733 * - we don't want to use a synchronous RPC thread, otherwise
734 * we might find ourselves hanging on a dead portmapper.
735 * - Some lockd implementations (e.g. HP) don't react to
736 * RPC_GRANTED calls; they seem to insist on RPC_GRANTED_MSG calls.
737 */
738static void
739nlmsvc_grant_blocked(struct nlm_block *block)
740{
741 struct nlm_file *file = block->b_file;
742 struct nlm_lock *lock = &block->b_call->a_args.lock;
743 int error;
744
745 dprintk("lockd: grant blocked lock %p\n", block);
746
747 kref_get(&block->b_count);
748
749 /* Unlink block request from list */
750 nlmsvc_unlink_block(block);
751
752 /* If b_granted is true this means we've been here before.
753 * Just retry the grant callback, possibly refreshing the RPC
754 * binding */
755 if (block->b_granted) {
756 nlm_rebind_host(block->b_host);
757 goto callback;
758 }
759
760 /* Try the lock operation again */
761 lock->fl.fl_flags |= FL_SLEEP;
762 error = vfs_lock_file(file->f_file, F_SETLK, &lock->fl, NULL);
763 lock->fl.fl_flags &= ~FL_SLEEP;
764
765 switch (error) {
766 case 0:
767 break;
768 case FILE_LOCK_DEFERRED:
769 dprintk("lockd: lock still blocked error %d\n", error);
770 nlmsvc_insert_block(block, NLM_NEVER);
771 nlmsvc_release_block(block);
772 return;
773 default:
774 printk(KERN_WARNING "lockd: unexpected error %d in %s!\n",
775 -error, __func__);
776 nlmsvc_insert_block(block, 10 * HZ);
777 nlmsvc_release_block(block);
778 return;
779 }
780
781callback:
782 /* Lock was granted by VFS. */
783 dprintk("lockd: GRANTing blocked lock.\n");
784 block->b_granted = 1;
785
786 /* keep block on the list, but don't reattempt until the RPC
787 * completes or the submission fails
788 */
789 nlmsvc_insert_block(block, NLM_NEVER);
790
791 /* Call the client -- use a soft RPC task since nlmsvc_retry_blocked
792 * will queue up a new one if this one times out
793 */
794 error = nlm_async_call(block->b_call, NLMPROC_GRANTED_MSG,
795 &nlmsvc_grant_ops);
796
797 /* RPC submission failed, wait a bit and retry */
798 if (error < 0)
799 nlmsvc_insert_block(block, 10 * HZ);
800}
801
802/*
803 * This is the callback from the RPC layer when the NLM_GRANTED_MSG
804 * RPC call has succeeded or timed out.
805 * Like all RPC callbacks, it is invoked by the rpciod process, so it
806 * better not sleep. Therefore, we put the blocked lock on the nlm_blocked
807 * chain once more in order to have it removed by lockd itself (which can
808 * then sleep on the file semaphore without disrupting e.g. the nfs client).
809 */
810static void nlmsvc_grant_callback(struct rpc_task *task, void *data)
811{
812 struct nlm_rqst *call = data;
813 struct nlm_block *block = call->a_block;
814 unsigned long timeout;
815
816 dprintk("lockd: GRANT_MSG RPC callback\n");
817
818 spin_lock(&nlm_blocked_lock);
819 /* if the block is not on a list at this point then it has
820 * been invalidated. Don't try to requeue it.
821 *
822 * FIXME: it's possible that the block is removed from the list
823 * after this check but before the nlmsvc_insert_block. In that
824 * case it will be added back. Perhaps we need better locking
825 * for nlm_blocked?
826 */
827 if (list_empty(&block->b_list))
828 goto out;
829
830 /* Technically, we should down the file semaphore here. Since we
831 * move the block towards the head of the queue only, no harm
832 * can be done, though. */
833 if (task->tk_status < 0) {
834 /* RPC error: Re-insert for retransmission */
835 timeout = 10 * HZ;
836 } else {
837 /* Call was successful, now wait for client callback */
838 timeout = 60 * HZ;
839 }
840 nlmsvc_insert_block_locked(block, timeout);
841 svc_wake_up(block->b_daemon);
842out:
843 spin_unlock(&nlm_blocked_lock);
844}
845
846/*
847 * FIXME: nlmsvc_release_block() grabs a mutex. This is not allowed for an
848 * .rpc_release rpc_call_op
849 */
850static void nlmsvc_grant_release(void *data)
851{
852 struct nlm_rqst *call = data;
853 nlmsvc_release_block(call->a_block);
854}
855
856static const struct rpc_call_ops nlmsvc_grant_ops = {
857 .rpc_call_done = nlmsvc_grant_callback,
858 .rpc_release = nlmsvc_grant_release,
859};
860
861/*
862 * We received a GRANT_RES callback. Try to find the corresponding
863 * block.
864 */
865void
866nlmsvc_grant_reply(struct nlm_cookie *cookie, __be32 status)
867{
868 struct nlm_block *block;
869
870 dprintk("grant_reply: looking for cookie %x, s=%d \n",
871 *(unsigned int *)(cookie->data), status);
872 if (!(block = nlmsvc_find_block(cookie)))
873 return;
874
875 if (block) {
876 if (status == nlm_lck_denied_grace_period) {
877 /* Try again in a couple of seconds */
878 nlmsvc_insert_block(block, 10 * HZ);
879 } else {
880 /* Lock is now held by client, or has been rejected.
881 * In both cases, the block should be removed. */
882 nlmsvc_unlink_block(block);
883 }
884 }
885 nlmsvc_release_block(block);
886}
887
888/* Helper function to handle retry of a deferred block.
889 * If it is a blocking lock, call grant_blocked.
890 * For a non-blocking lock or test lock, revisit the request.
891 */
892static void
893retry_deferred_block(struct nlm_block *block)
894{
895 if (!(block->b_flags & B_GOT_CALLBACK))
896 block->b_flags |= B_TIMED_OUT;
897 nlmsvc_insert_block(block, NLM_TIMEOUT);
898 dprintk("revisit block %p flags %d\n", block, block->b_flags);
899 if (block->b_deferred_req) {
900 block->b_deferred_req->revisit(block->b_deferred_req, 0);
901 block->b_deferred_req = NULL;
902 }
903}
904
905/*
906 * Retry all blocked locks that have been notified. This is where lockd
907 * picks up locks that can be granted, or grant notifications that must
908 * be retransmitted.
909 */
910unsigned long
911nlmsvc_retry_blocked(void)
912{
913 unsigned long timeout = MAX_SCHEDULE_TIMEOUT;
914 struct nlm_block *block;
915
916 while (!list_empty(&nlm_blocked) && !kthread_should_stop()) {
917 block = list_entry(nlm_blocked.next, struct nlm_block, b_list);
918
919 if (block->b_when == NLM_NEVER)
920 break;
921 if (time_after(block->b_when, jiffies)) {
922 timeout = block->b_when - jiffies;
923 break;
924 }
925
926 dprintk("nlmsvc_retry_blocked(%p, when=%ld)\n",
927 block, block->b_when);
928 if (block->b_flags & B_QUEUED) {
929 dprintk("nlmsvc_retry_blocked delete block (%p, granted=%d, flags=%d)\n",
930 block, block->b_granted, block->b_flags);
931 retry_deferred_block(block);
932 } else
933 nlmsvc_grant_blocked(block);
934 }
935
936 return timeout;
937}
938
939#ifdef RPC_DEBUG
940static const char *nlmdbg_cookie2a(const struct nlm_cookie *cookie)
941{
942 /*
943 * We can get away with a static buffer because we're only
944 * called with BKL held.
945 */
946 static char buf[2*NLM_MAXCOOKIELEN+1];
947 unsigned int i, len = sizeof(buf);
948 char *p = buf;
949
950 len--; /* allow for trailing \0 */
951 if (len < 3)
952 return "???";
953 for (i = 0 ; i < cookie->len ; i++) {
954 if (len < 2) {
955 strcpy(p-3, "...");
956 break;
957 }
958 sprintf(p, "%02x", cookie->data[i]);
959 p += 2;
960 len -= 2;
961 }
962 *p = '\0';
963
964 return buf;
965}
966#endif