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
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#if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
57static const char *nlmdbg_cookie2a(const struct nlm_cookie *cookie)
58{
59 /*
60 * We can get away with a static buffer because this is only called
61 * from lockd, which is single-threaded.
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: p-3, q: "...");
73 break;
74 }
75 sprintf(buf: p, fmt: "%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(head: &block->b_list)) {
96 kref_get(kref: &block->b_count);
97 } else {
98 list_del_init(entry: &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(new: &block->b_list, head: pos);
116 block->b_when = when;
117}
118
119static void nlmsvc_insert_block(struct nlm_block *block, unsigned long when)
120{
121 spin_lock(lock: &nlm_blocked_lock);
122 nlmsvc_insert_block_locked(block, when);
123 spin_unlock(lock: &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 spin_lock(lock: &nlm_blocked_lock);
133 if (!list_empty(head: &block->b_list)) {
134 list_del_init(entry: &block->b_list);
135 spin_unlock(lock: &nlm_blocked_lock);
136 nlmsvc_release_block(block);
137 return;
138 }
139 spin_unlock(lock: &nlm_blocked_lock);
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.c.flc_pid,
153 (long long)lock->fl.fl_start,
154 (long long)lock->fl.fl_end,
155 lock->fl.c.flc_type);
156 spin_lock(lock: &nlm_blocked_lock);
157 list_for_each_entry(block, &nlm_blocked, b_list) {
158 fl = &block->b_call->a_args.lock.fl;
159 dprintk("lockd: check f=%p pd=%d %Ld-%Ld ty=%d cookie=%s\n",
160 block->b_file, fl->c.flc_pid,
161 (long long)fl->fl_start,
162 (long long)fl->fl_end, fl->c.flc_type,
163 nlmdbg_cookie2a(&block->b_call->a_args.cookie));
164 if (block->b_file == file && nlm_compare_locks(fl1: fl, fl2: &lock->fl)) {
165 kref_get(kref: &block->b_count);
166 spin_unlock(lock: &nlm_blocked_lock);
167 return block;
168 }
169 }
170 spin_unlock(lock: &nlm_blocked_lock);
171
172 return NULL;
173}
174
175static inline int nlm_cookie_match(struct nlm_cookie *a, struct nlm_cookie *b)
176{
177 if (a->len != b->len)
178 return 0;
179 if (memcmp(p: a->data, q: b->data, size: a->len))
180 return 0;
181 return 1;
182}
183
184/*
185 * Find a block with a given NLM cookie.
186 */
187static inline struct nlm_block *
188nlmsvc_find_block(struct nlm_cookie *cookie)
189{
190 struct nlm_block *block;
191
192 spin_lock(lock: &nlm_blocked_lock);
193 list_for_each_entry(block, &nlm_blocked, b_list) {
194 if (nlm_cookie_match(a: &block->b_call->a_args.cookie,b: cookie))
195 goto found;
196 }
197 spin_unlock(lock: &nlm_blocked_lock);
198
199 return NULL;
200
201found:
202 dprintk("nlmsvc_find_block(%s): block=%p\n", nlmdbg_cookie2a(cookie), block);
203 kref_get(kref: &block->b_count);
204 spin_unlock(lock: &nlm_blocked_lock);
205 return block;
206}
207
208/*
209 * Create a block and initialize it.
210 *
211 * Note: we explicitly set the cookie of the grant reply to that of
212 * the blocked lock request. The spec explicitly mentions that the client
213 * should _not_ rely on the callback containing the same cookie as the
214 * request, but (as I found out later) that's because some implementations
215 * do just this. Never mind the standards comittees, they support our
216 * logging industries.
217 *
218 * 10 years later: I hope we can safely ignore these old and broken
219 * clients by now. Let's fix this so we can uniquely identify an incoming
220 * GRANTED_RES message by cookie, without having to rely on the client's IP
221 * address. --okir
222 */
223static struct nlm_block *
224nlmsvc_create_block(struct svc_rqst *rqstp, struct nlm_host *host,
225 struct nlm_file *file, struct nlm_lock *lock,
226 struct nlm_cookie *cookie)
227{
228 struct nlm_block *block;
229 struct nlm_rqst *call = NULL;
230
231 call = nlm_alloc_call(host);
232 if (call == NULL)
233 return NULL;
234
235 /* Allocate memory for block, and initialize arguments */
236 block = kzalloc(sizeof(*block), GFP_KERNEL);
237 if (block == NULL)
238 goto failed;
239 kref_init(kref: &block->b_count);
240 INIT_LIST_HEAD(list: &block->b_list);
241 INIT_LIST_HEAD(list: &block->b_flist);
242
243 if (!nlmsvc_setgrantargs(call, lock))
244 goto failed_free;
245
246 /* Set notifier function for VFS, and init args */
247 call->a_args.lock.fl.c.flc_flags |= FL_SLEEP;
248 call->a_args.lock.fl.fl_lmops = &nlmsvc_lock_operations;
249 nlmclnt_next_cookie(&call->a_args.cookie);
250
251 dprintk("lockd: created block %p...\n", block);
252
253 /* Create and initialize the block */
254 block->b_daemon = rqstp->rq_server;
255 block->b_host = host;
256 block->b_file = file;
257 file->f_count++;
258
259 /* Add to file's list of blocks */
260 list_add(new: &block->b_flist, head: &file->f_blocks);
261
262 /* Set up RPC arguments for callback */
263 block->b_call = call;
264 call->a_flags = RPC_TASK_ASYNC;
265 call->a_block = block;
266
267 return block;
268
269failed_free:
270 kfree(objp: block);
271failed:
272 nlmsvc_release_call(call);
273 return NULL;
274}
275
276/*
277 * Delete a block.
278 * It is the caller's responsibility to check whether the file
279 * can be closed hereafter.
280 */
281static int nlmsvc_unlink_block(struct nlm_block *block)
282{
283 int status;
284 dprintk("lockd: unlinking block %p...\n", block);
285
286 /* Remove block from list */
287 status = locks_delete_block(&block->b_call->a_args.lock.fl);
288 nlmsvc_remove_block(block);
289 return status;
290}
291
292static void nlmsvc_free_block(struct kref *kref)
293{
294 struct nlm_block *block = container_of(kref, struct nlm_block, b_count);
295 struct nlm_file *file = block->b_file;
296
297 dprintk("lockd: freeing block %p...\n", block);
298
299 /* Remove block from file's list of blocks */
300 list_del_init(entry: &block->b_flist);
301 mutex_unlock(lock: &file->f_mutex);
302
303 nlmsvc_freegrantargs(call: block->b_call);
304 nlmsvc_release_call(block->b_call);
305 nlm_release_file(block->b_file);
306 kfree(objp: block);
307}
308
309static void nlmsvc_release_block(struct nlm_block *block)
310{
311 if (block != NULL)
312 kref_put_mutex(kref: &block->b_count, release: nlmsvc_free_block, mutex: &block->b_file->f_mutex);
313}
314
315/*
316 * Loop over all blocks and delete blocks held by
317 * a matching host.
318 */
319void nlmsvc_traverse_blocks(struct nlm_host *host,
320 struct nlm_file *file,
321 nlm_host_match_fn_t match)
322{
323 struct nlm_block *block, *next;
324
325restart:
326 mutex_lock(&file->f_mutex);
327 spin_lock(lock: &nlm_blocked_lock);
328 list_for_each_entry_safe(block, next, &file->f_blocks, b_flist) {
329 if (!match(block->b_host, host))
330 continue;
331 /* Do not destroy blocks that are not on
332 * the global retry list - why? */
333 if (list_empty(head: &block->b_list))
334 continue;
335 kref_get(kref: &block->b_count);
336 spin_unlock(lock: &nlm_blocked_lock);
337 mutex_unlock(lock: &file->f_mutex);
338 nlmsvc_unlink_block(block);
339 nlmsvc_release_block(block);
340 goto restart;
341 }
342 spin_unlock(lock: &nlm_blocked_lock);
343 mutex_unlock(lock: &file->f_mutex);
344}
345
346static struct nlm_lockowner *
347nlmsvc_get_lockowner(struct nlm_lockowner *lockowner)
348{
349 refcount_inc(r: &lockowner->count);
350 return lockowner;
351}
352
353void nlmsvc_put_lockowner(struct nlm_lockowner *lockowner)
354{
355 if (!refcount_dec_and_lock(r: &lockowner->count, lock: &lockowner->host->h_lock))
356 return;
357 list_del(entry: &lockowner->list);
358 spin_unlock(lock: &lockowner->host->h_lock);
359 nlmsvc_release_host(lockowner->host);
360 kfree(objp: lockowner);
361}
362
363static struct nlm_lockowner *__nlmsvc_find_lockowner(struct nlm_host *host, pid_t pid)
364{
365 struct nlm_lockowner *lockowner;
366 list_for_each_entry(lockowner, &host->h_lockowners, list) {
367 if (lockowner->pid != pid)
368 continue;
369 return nlmsvc_get_lockowner(lockowner);
370 }
371 return NULL;
372}
373
374static struct nlm_lockowner *nlmsvc_find_lockowner(struct nlm_host *host, pid_t pid)
375{
376 struct nlm_lockowner *res, *new = NULL;
377
378 spin_lock(lock: &host->h_lock);
379 res = __nlmsvc_find_lockowner(host, pid);
380
381 if (res == NULL) {
382 spin_unlock(lock: &host->h_lock);
383 new = kmalloc(sizeof(*res), GFP_KERNEL);
384 spin_lock(lock: &host->h_lock);
385 res = __nlmsvc_find_lockowner(host, pid);
386 if (res == NULL && new != NULL) {
387 res = new;
388 /* fs/locks.c will manage the refcount through lock_ops */
389 refcount_set(r: &new->count, n: 1);
390 new->pid = pid;
391 new->host = nlm_get_host(host);
392 list_add(new: &new->list, head: &host->h_lockowners);
393 new = NULL;
394 }
395 }
396
397 spin_unlock(lock: &host->h_lock);
398 kfree(objp: new);
399 return res;
400}
401
402void
403nlmsvc_release_lockowner(struct nlm_lock *lock)
404{
405 if (lock->fl.c.flc_owner)
406 nlmsvc_put_lockowner(lockowner: lock->fl.c.flc_owner);
407}
408
409void nlmsvc_locks_init_private(struct file_lock *fl, struct nlm_host *host,
410 pid_t pid)
411{
412 fl->c.flc_owner = nlmsvc_find_lockowner(host, pid);
413}
414
415/*
416 * Initialize arguments for GRANTED call. The nlm_rqst structure
417 * has been cleared already.
418 */
419static int nlmsvc_setgrantargs(struct nlm_rqst *call, struct nlm_lock *lock)
420{
421 locks_copy_lock(&call->a_args.lock.fl, &lock->fl);
422 memcpy(&call->a_args.lock.fh, &lock->fh, sizeof(call->a_args.lock.fh));
423 call->a_args.lock.caller = utsname()->nodename;
424 call->a_args.lock.oh.len = lock->oh.len;
425
426 /* set default data area */
427 call->a_args.lock.oh.data = call->a_owner;
428 call->a_args.lock.svid = ((struct nlm_lockowner *) lock->fl.c.flc_owner)->pid;
429
430 if (lock->oh.len > NLMCLNT_OHSIZE) {
431 void *data = kmalloc(lock->oh.len, GFP_KERNEL);
432 if (!data)
433 return 0;
434 call->a_args.lock.oh.data = (u8 *) data;
435 }
436
437 memcpy(call->a_args.lock.oh.data, lock->oh.data, lock->oh.len);
438 return 1;
439}
440
441static void nlmsvc_freegrantargs(struct nlm_rqst *call)
442{
443 if (call->a_args.lock.oh.data != call->a_owner)
444 kfree(objp: call->a_args.lock.oh.data);
445
446 locks_release_private(&call->a_args.lock.fl);
447}
448
449/*
450 * Deferred lock request handling for non-blocking lock
451 */
452static __be32
453nlmsvc_defer_lock_rqst(struct svc_rqst *rqstp, struct nlm_block *block)
454{
455 __be32 status = nlm_lck_denied_nolocks;
456
457 block->b_flags |= B_QUEUED;
458
459 nlmsvc_insert_block(block, NLM_TIMEOUT);
460
461 block->b_cache_req = &rqstp->rq_chandle;
462 if (rqstp->rq_chandle.defer) {
463 block->b_deferred_req =
464 rqstp->rq_chandle.defer(block->b_cache_req);
465 if (block->b_deferred_req != NULL)
466 status = nlm_drop_reply;
467 }
468 dprintk("lockd: nlmsvc_defer_lock_rqst block %p flags %d status %d\n",
469 block, block->b_flags, ntohl(status));
470
471 return status;
472}
473
474/*
475 * Attempt to establish a lock, and if it can't be granted, block it
476 * if required.
477 */
478__be32
479nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file,
480 struct nlm_host *host, struct nlm_lock *lock, int wait,
481 struct nlm_cookie *cookie, int reclaim)
482{
483 struct inode *inode __maybe_unused = nlmsvc_file_inode(file);
484 struct nlm_block *block = NULL;
485 int error;
486 int mode;
487 int async_block = 0;
488 __be32 ret;
489
490 dprintk("lockd: nlmsvc_lock(%s/%ld, ty=%d, pi=%d, %Ld-%Ld, bl=%d)\n",
491 inode->i_sb->s_id, inode->i_ino,
492 lock->fl.c.flc_type,
493 lock->fl.c.flc_pid,
494 (long long)lock->fl.fl_start,
495 (long long)lock->fl.fl_end,
496 wait);
497
498 if (nlmsvc_file_cannot_lock(file))
499 return nlm_lck_denied_nolocks;
500
501 if (!locks_can_async_lock(fops: nlmsvc_file_file(file)->f_op)) {
502 async_block = wait;
503 wait = 0;
504 }
505
506 /* Lock file against concurrent access */
507 mutex_lock(&file->f_mutex);
508 /* Get existing block (in case client is busy-waiting)
509 * or create new block
510 */
511 block = nlmsvc_lookup_block(file, lock);
512 if (block == NULL) {
513 block = nlmsvc_create_block(rqstp, host, file, lock, cookie);
514 ret = nlm_lck_denied_nolocks;
515 if (block == NULL)
516 goto out;
517 lock = &block->b_call->a_args.lock;
518 } else
519 lock->fl.c.flc_flags &= ~FL_SLEEP;
520
521 if (block->b_flags & B_QUEUED) {
522 dprintk("lockd: nlmsvc_lock deferred block %p flags %d\n",
523 block, block->b_flags);
524 if (block->b_granted) {
525 nlmsvc_unlink_block(block);
526 ret = nlm_granted;
527 goto out;
528 }
529 if (block->b_flags & B_TIMED_OUT) {
530 nlmsvc_unlink_block(block);
531 ret = nlm_lck_denied;
532 goto out;
533 }
534 ret = nlm_drop_reply;
535 goto out;
536 }
537
538 if (locks_in_grace(SVC_NET(rqstp)) && !reclaim) {
539 ret = nlm_lck_denied_grace_period;
540 goto out;
541 }
542 if (reclaim && !locks_in_grace(SVC_NET(rqstp))) {
543 ret = nlm_lck_denied_grace_period;
544 goto out;
545 }
546
547 spin_lock(lock: &nlm_blocked_lock);
548 /*
549 * If this is a lock request for an already pending
550 * lock request we return nlm_lck_blocked without calling
551 * vfs_lock_file() again. Otherwise we have two pending
552 * requests on the underlaying ->lock() implementation but
553 * only one nlm_block to being granted by lm_grant().
554 */
555 if (locks_can_async_lock(fops: nlmsvc_file_file(file)->f_op) &&
556 !list_empty(head: &block->b_list)) {
557 spin_unlock(lock: &nlm_blocked_lock);
558 ret = nlm_lck_blocked;
559 goto out;
560 }
561
562 /* Append to list of blocked */
563 nlmsvc_insert_block_locked(block, NLM_NEVER);
564 spin_unlock(lock: &nlm_blocked_lock);
565
566 if (!wait)
567 lock->fl.c.flc_flags &= ~FL_SLEEP;
568 mode = lock_to_openmode(&lock->fl);
569 error = vfs_lock_file(file->f_file[mode], F_SETLK, &lock->fl, NULL);
570 lock->fl.c.flc_flags &= ~FL_SLEEP;
571
572 dprintk("lockd: vfs_lock_file returned %d\n", error);
573 switch (error) {
574 case 0:
575 nlmsvc_remove_block(block);
576 ret = nlm_granted;
577 goto out;
578 case -EAGAIN:
579 if (!wait)
580 nlmsvc_remove_block(block);
581 ret = async_block ? nlm_lck_blocked : nlm_lck_denied;
582 goto out;
583 case FILE_LOCK_DEFERRED:
584 if (wait)
585 break;
586 /* Filesystem lock operation is in progress
587 Add it to the queue waiting for callback */
588 ret = nlmsvc_defer_lock_rqst(rqstp, block);
589 goto out;
590 case -EDEADLK:
591 nlmsvc_remove_block(block);
592 ret = nlm_deadlock;
593 goto out;
594 default: /* includes ENOLCK */
595 nlmsvc_remove_block(block);
596 ret = nlm_lck_denied_nolocks;
597 goto out;
598 }
599
600 ret = nlm_lck_blocked;
601out:
602 mutex_unlock(lock: &file->f_mutex);
603 nlmsvc_release_block(block);
604 dprintk("lockd: nlmsvc_lock returned %u\n", ret);
605 return ret;
606}
607
608/*
609 * Test for presence of a conflicting lock.
610 */
611__be32
612nlmsvc_testlock(struct svc_rqst *rqstp, struct nlm_file *file,
613 struct nlm_host *host, struct nlm_lock *lock,
614 struct nlm_lock *conflock)
615{
616 int error;
617 int mode;
618 __be32 ret;
619
620 dprintk("lockd: nlmsvc_testlock(%s/%ld, ty=%d, %Ld-%Ld)\n",
621 nlmsvc_file_inode(file)->i_sb->s_id,
622 nlmsvc_file_inode(file)->i_ino,
623 lock->fl.c.flc_type,
624 (long long)lock->fl.fl_start,
625 (long long)lock->fl.fl_end);
626
627 if (nlmsvc_file_cannot_lock(file))
628 return nlm_lck_denied_nolocks;
629
630 if (locks_in_grace(SVC_NET(rqstp))) {
631 ret = nlm_lck_denied_grace_period;
632 goto out;
633 }
634
635 mode = lock_to_openmode(&lock->fl);
636 locks_init_lock(&conflock->fl);
637 /* vfs_test_lock only uses start, end, and owner, but tests flc_file */
638 conflock->fl.c.flc_file = lock->fl.c.flc_file;
639 conflock->fl.fl_start = lock->fl.fl_start;
640 conflock->fl.fl_end = lock->fl.fl_end;
641 conflock->fl.c.flc_owner = lock->fl.c.flc_owner;
642 error = vfs_test_lock(file->f_file[mode], &conflock->fl);
643 if (error) {
644 /* We can't currently deal with deferred test requests */
645 if (error == FILE_LOCK_DEFERRED)
646 WARN_ON_ONCE(1);
647
648 ret = nlm_lck_denied_nolocks;
649 goto out;
650 }
651
652 if (conflock->fl.c.flc_type == F_UNLCK) {
653 ret = nlm_granted;
654 goto out;
655 }
656
657 dprintk("lockd: conflicting lock(ty=%d, %Ld-%Ld)\n",
658 conflock->fl.c.flc_type, (long long)conflock->fl.fl_start,
659 (long long)conflock->fl.fl_end);
660 conflock->caller = "somehost"; /* FIXME */
661 conflock->len = strlen(conflock->caller);
662 conflock->oh.len = 0; /* don't return OH info */
663 conflock->svid = conflock->fl.c.flc_pid;
664 locks_release_private(&conflock->fl);
665
666 ret = nlm_lck_denied;
667out:
668 return ret;
669}
670
671/*
672 * Remove a lock.
673 * This implies a CANCEL call: We send a GRANT_MSG, the client replies
674 * with a GRANT_RES call which gets lost, and calls UNLOCK immediately
675 * afterwards. In this case the block will still be there, and hence
676 * must be removed.
677 */
678__be32
679nlmsvc_unlock(struct net *net, struct nlm_file *file, struct nlm_lock *lock)
680{
681 int error = 0;
682
683 dprintk("lockd: nlmsvc_unlock(%s/%ld, pi=%d, %Ld-%Ld)\n",
684 nlmsvc_file_inode(file)->i_sb->s_id,
685 nlmsvc_file_inode(file)->i_ino,
686 lock->fl.c.flc_pid,
687 (long long)lock->fl.fl_start,
688 (long long)lock->fl.fl_end);
689
690 if (nlmsvc_file_cannot_lock(file))
691 return nlm_lck_denied_nolocks;
692
693 /* First, cancel any lock that might be there */
694 nlmsvc_cancel_blocked(net, file, lock);
695
696 lock->fl.c.flc_type = F_UNLCK;
697 lock->fl.c.flc_file = file->f_file[O_RDONLY];
698 if (lock->fl.c.flc_file)
699 error = vfs_lock_file(lock->fl.c.flc_file, F_SETLK,
700 &lock->fl, NULL);
701 lock->fl.c.flc_file = file->f_file[O_WRONLY];
702 if (lock->fl.c.flc_file)
703 error |= vfs_lock_file(lock->fl.c.flc_file, F_SETLK,
704 &lock->fl, NULL);
705
706 return (error < 0)? nlm_lck_denied_nolocks : nlm_granted;
707}
708
709/*
710 * Cancel a previously blocked request.
711 *
712 * A cancel request always overrides any grant that may currently
713 * be in progress.
714 * The calling procedure must check whether the file can be closed.
715 */
716__be32
717nlmsvc_cancel_blocked(struct net *net, struct nlm_file *file, struct nlm_lock *lock)
718{
719 struct nlm_block *block;
720 int status = 0;
721 int mode;
722
723 dprintk("lockd: nlmsvc_cancel(%s/%ld, pi=%d, %Ld-%Ld)\n",
724 nlmsvc_file_inode(file)->i_sb->s_id,
725 nlmsvc_file_inode(file)->i_ino,
726 lock->fl.c.flc_pid,
727 (long long)lock->fl.fl_start,
728 (long long)lock->fl.fl_end);
729
730 if (nlmsvc_file_cannot_lock(file))
731 return nlm_lck_denied_nolocks;
732
733 if (locks_in_grace(net))
734 return nlm_lck_denied_grace_period;
735
736 mutex_lock(&file->f_mutex);
737 block = nlmsvc_lookup_block(file, lock);
738 mutex_unlock(lock: &file->f_mutex);
739 if (block != NULL) {
740 struct file_lock *fl = &block->b_call->a_args.lock.fl;
741
742 mode = lock_to_openmode(fl);
743 vfs_cancel_lock(filp: block->b_file->f_file[mode], fl);
744 status = nlmsvc_unlink_block(block);
745 nlmsvc_release_block(block);
746 }
747 return status ? nlm_lck_denied : nlm_granted;
748}
749
750/*
751 * This is a callback from the filesystem for VFS file lock requests.
752 * It will be used if lm_grant is defined and the filesystem can not
753 * respond to the request immediately.
754 * For SETLK or SETLKW request it will get the local posix lock.
755 * In all cases it will move the block to the head of nlm_blocked q where
756 * nlmsvc_retry_blocked() can send back a reply for SETLKW or revisit the
757 * deferred rpc for GETLK and SETLK.
758 */
759static void
760nlmsvc_update_deferred_block(struct nlm_block *block, int result)
761{
762 block->b_flags |= B_GOT_CALLBACK;
763 if (result == 0)
764 block->b_granted = 1;
765 else
766 block->b_flags |= B_TIMED_OUT;
767}
768
769static int nlmsvc_grant_deferred(struct file_lock *fl, int result)
770{
771 struct nlm_block *block;
772 int rc = -ENOENT;
773
774 spin_lock(lock: &nlm_blocked_lock);
775 list_for_each_entry(block, &nlm_blocked, b_list) {
776 if (nlm_compare_locks(fl1: &block->b_call->a_args.lock.fl, fl2: fl)) {
777 dprintk("lockd: nlmsvc_notify_blocked block %p flags %d\n",
778 block, block->b_flags);
779 if (block->b_flags & B_QUEUED) {
780 if (block->b_flags & B_TIMED_OUT) {
781 rc = -ENOLCK;
782 break;
783 }
784 nlmsvc_update_deferred_block(block, result);
785 } else if (result == 0)
786 block->b_granted = 1;
787
788 nlmsvc_insert_block_locked(block, when: 0);
789 svc_wake_up(block->b_daemon);
790 rc = 0;
791 break;
792 }
793 }
794 spin_unlock(lock: &nlm_blocked_lock);
795 if (rc == -ENOENT)
796 printk(KERN_WARNING "lockd: grant for unknown block\n");
797 return rc;
798}
799
800/*
801 * Unblock a blocked lock request. This is a callback invoked from the
802 * VFS layer when a lock on which we blocked is removed.
803 *
804 * This function doesn't grant the blocked lock instantly, but rather moves
805 * the block to the head of nlm_blocked where it can be picked up by lockd.
806 */
807static void
808nlmsvc_notify_blocked(struct file_lock *fl)
809{
810 struct nlm_block *block;
811
812 dprintk("lockd: VFS unblock notification for block %p\n", fl);
813 spin_lock(lock: &nlm_blocked_lock);
814 list_for_each_entry(block, &nlm_blocked, b_list) {
815 if (nlm_compare_locks(fl1: &block->b_call->a_args.lock.fl, fl2: fl)) {
816 nlmsvc_insert_block_locked(block, when: 0);
817 spin_unlock(lock: &nlm_blocked_lock);
818 svc_wake_up(block->b_daemon);
819 return;
820 }
821 }
822 spin_unlock(lock: &nlm_blocked_lock);
823 printk(KERN_WARNING "lockd: notification for unknown block!\n");
824}
825
826static fl_owner_t nlmsvc_get_owner(fl_owner_t owner)
827{
828 return nlmsvc_get_lockowner(lockowner: owner);
829}
830
831static void nlmsvc_put_owner(fl_owner_t owner)
832{
833 nlmsvc_put_lockowner(lockowner: owner);
834}
835
836const struct lock_manager_operations nlmsvc_lock_operations = {
837 .lm_notify = nlmsvc_notify_blocked,
838 .lm_grant = nlmsvc_grant_deferred,
839 .lm_get_owner = nlmsvc_get_owner,
840 .lm_put_owner = nlmsvc_put_owner,
841};
842
843/*
844 * Try to claim a lock that was previously blocked.
845 *
846 * Note that we use both the RPC_GRANTED_MSG call _and_ an async
847 * RPC thread when notifying the client. This seems like overkill...
848 * Here's why:
849 * - we don't want to use a synchronous RPC thread, otherwise
850 * we might find ourselves hanging on a dead portmapper.
851 * - Some lockd implementations (e.g. HP) don't react to
852 * RPC_GRANTED calls; they seem to insist on RPC_GRANTED_MSG calls.
853 */
854static void
855nlmsvc_grant_blocked(struct nlm_block *block)
856{
857 struct nlm_file *file = block->b_file;
858 struct nlm_lock *lock = &block->b_call->a_args.lock;
859 int mode;
860 int error;
861 loff_t fl_start, fl_end;
862
863 dprintk("lockd: grant blocked lock %p\n", block);
864
865 kref_get(kref: &block->b_count);
866
867 /* Unlink block request from list */
868 nlmsvc_unlink_block(block);
869
870 /* If b_granted is true this means we've been here before.
871 * Just retry the grant callback, possibly refreshing the RPC
872 * binding */
873 if (block->b_granted) {
874 nlm_rebind_host(block->b_host);
875 goto callback;
876 }
877
878 /* Try the lock operation again */
879 /* vfs_lock_file() can mangle fl_start and fl_end, but we need
880 * them unchanged for the GRANT_MSG
881 */
882 lock->fl.c.flc_flags |= FL_SLEEP;
883 fl_start = lock->fl.fl_start;
884 fl_end = lock->fl.fl_end;
885 mode = lock_to_openmode(&lock->fl);
886 error = vfs_lock_file(file->f_file[mode], F_SETLK, &lock->fl, NULL);
887 lock->fl.c.flc_flags &= ~FL_SLEEP;
888 lock->fl.fl_start = fl_start;
889 lock->fl.fl_end = fl_end;
890
891 switch (error) {
892 case 0:
893 break;
894 case FILE_LOCK_DEFERRED:
895 dprintk("lockd: lock still blocked error %d\n", error);
896 nlmsvc_insert_block(block, NLM_NEVER);
897 nlmsvc_release_block(block);
898 return;
899 default:
900 printk(KERN_WARNING "lockd: unexpected error %d in %s!\n",
901 -error, __func__);
902 nlmsvc_insert_block(block, when: 10 * HZ);
903 nlmsvc_release_block(block);
904 return;
905 }
906
907callback:
908 /* Lock was granted by VFS. */
909 dprintk("lockd: GRANTing blocked lock.\n");
910 block->b_granted = 1;
911
912 /* keep block on the list, but don't reattempt until the RPC
913 * completes or the submission fails
914 */
915 nlmsvc_insert_block(block, NLM_NEVER);
916
917 /* Call the client -- use a soft RPC task since nlmsvc_retry_blocked
918 * will queue up a new one if this one times out
919 */
920 error = nlm_async_call(block->b_call, NLMPROC_GRANTED_MSG,
921 &nlmsvc_grant_ops);
922
923 /* RPC submission failed, wait a bit and retry */
924 if (error < 0)
925 nlmsvc_insert_block(block, when: 10 * HZ);
926}
927
928/*
929 * This is the callback from the RPC layer when the NLM_GRANTED_MSG
930 * RPC call has succeeded or timed out.
931 * Like all RPC callbacks, it is invoked by the rpciod process, so it
932 * better not sleep. Therefore, we put the blocked lock on the nlm_blocked
933 * chain once more in order to have it removed by lockd itself (which can
934 * then sleep on the file semaphore without disrupting e.g. the nfs client).
935 */
936static void nlmsvc_grant_callback(struct rpc_task *task, void *data)
937{
938 struct nlm_rqst *call = data;
939 struct nlm_block *block = call->a_block;
940 unsigned long timeout;
941
942 dprintk("lockd: GRANT_MSG RPC callback\n");
943
944 spin_lock(lock: &nlm_blocked_lock);
945 /* if the block is not on a list at this point then it has
946 * been invalidated. Don't try to requeue it.
947 *
948 * FIXME: it's possible that the block is removed from the list
949 * after this check but before the nlmsvc_insert_block. In that
950 * case it will be added back. Perhaps we need better locking
951 * for nlm_blocked?
952 */
953 if (list_empty(head: &block->b_list))
954 goto out;
955
956 /* Technically, we should down the file semaphore here. Since we
957 * move the block towards the head of the queue only, no harm
958 * can be done, though. */
959 if (task->tk_status < 0) {
960 /* RPC error: Re-insert for retransmission */
961 timeout = 10 * HZ;
962 } else {
963 /* Call was successful, now wait for client callback */
964 timeout = 60 * HZ;
965 }
966 nlmsvc_insert_block_locked(block, when: timeout);
967 svc_wake_up(block->b_daemon);
968out:
969 spin_unlock(lock: &nlm_blocked_lock);
970}
971
972/*
973 * FIXME: nlmsvc_release_block() grabs a mutex. This is not allowed for an
974 * .rpc_release rpc_call_op
975 */
976static void nlmsvc_grant_release(void *data)
977{
978 struct nlm_rqst *call = data;
979 nlmsvc_release_block(block: call->a_block);
980}
981
982static const struct rpc_call_ops nlmsvc_grant_ops = {
983 .rpc_call_done = nlmsvc_grant_callback,
984 .rpc_release = nlmsvc_grant_release,
985};
986
987/*
988 * We received a GRANT_RES callback. Try to find the corresponding
989 * block.
990 */
991void
992nlmsvc_grant_reply(struct nlm_cookie *cookie, __be32 status)
993{
994 struct nlm_block *block;
995 struct file_lock *fl;
996 int error;
997
998 dprintk("grant_reply: looking for cookie %x, s=%d\n",
999 *(unsigned int *)(cookie->data), status);
1000 if (!(block = nlmsvc_find_block(cookie)))
1001 return;
1002
1003 switch (status) {
1004 case nlm_lck_denied_grace_period:
1005 /* Try again in a couple of seconds */
1006 nlmsvc_insert_block(block, when: 10 * HZ);
1007 break;
1008 case nlm_lck_denied:
1009 /* Client doesn't want it, just unlock it */
1010 nlmsvc_unlink_block(block);
1011 fl = &block->b_call->a_args.lock.fl;
1012 fl->c.flc_type = F_UNLCK;
1013 error = vfs_lock_file(fl->c.flc_file, F_SETLK, fl, NULL);
1014 if (error)
1015 pr_warn("lockd: unable to unlock lock rejected by client!\n");
1016 break;
1017 default:
1018 /*
1019 * Either it was accepted or the status makes no sense
1020 * just unlink it either way.
1021 */
1022 nlmsvc_unlink_block(block);
1023 }
1024 nlmsvc_release_block(block);
1025}
1026
1027/* Helper function to handle retry of a deferred block.
1028 * If it is a blocking lock, call grant_blocked.
1029 * For a non-blocking lock or test lock, revisit the request.
1030 */
1031static void
1032retry_deferred_block(struct nlm_block *block)
1033{
1034 if (!(block->b_flags & B_GOT_CALLBACK))
1035 block->b_flags |= B_TIMED_OUT;
1036 nlmsvc_insert_block(block, NLM_TIMEOUT);
1037 dprintk("revisit block %p flags %d\n", block, block->b_flags);
1038 if (block->b_deferred_req) {
1039 block->b_deferred_req->revisit(block->b_deferred_req, 0);
1040 block->b_deferred_req = NULL;
1041 }
1042}
1043
1044/*
1045 * Retry all blocked locks that have been notified. This is where lockd
1046 * picks up locks that can be granted, or grant notifications that must
1047 * be retransmitted.
1048 */
1049void
1050nlmsvc_retry_blocked(struct svc_rqst *rqstp)
1051{
1052 unsigned long timeout = MAX_SCHEDULE_TIMEOUT;
1053 struct nlm_block *block;
1054
1055 spin_lock(lock: &nlm_blocked_lock);
1056 while (!list_empty(head: &nlm_blocked) && !svc_thread_should_stop(rqstp)) {
1057 block = list_entry(nlm_blocked.next, struct nlm_block, b_list);
1058
1059 if (block->b_when == NLM_NEVER)
1060 break;
1061 if (time_after(block->b_when, jiffies)) {
1062 timeout = block->b_when - jiffies;
1063 break;
1064 }
1065 spin_unlock(lock: &nlm_blocked_lock);
1066
1067 dprintk("nlmsvc_retry_blocked(%p, when=%ld)\n",
1068 block, block->b_when);
1069 if (block->b_flags & B_QUEUED) {
1070 dprintk("nlmsvc_retry_blocked delete block (%p, granted=%d, flags=%d)\n",
1071 block, block->b_granted, block->b_flags);
1072 retry_deferred_block(block);
1073 } else
1074 nlmsvc_grant_blocked(block);
1075 spin_lock(lock: &nlm_blocked_lock);
1076 }
1077 spin_unlock(lock: &nlm_blocked_lock);
1078
1079 if (timeout < MAX_SCHEDULE_TIMEOUT)
1080 mod_timer(timer: &nlmsvc_retry, expires: jiffies + timeout);
1081}
1082

source code of linux/fs/lockd/svclock.c