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/exportfs.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
43 static void nlmsvc_release_block(struct nlm_block *block);
44 static void nlmsvc_insert_block(struct nlm_block *block, unsigned long);
45 static void nlmsvc_remove_block(struct nlm_block *block);
46
47 static int nlmsvc_setgrantargs(struct nlm_rqst *call, struct nlm_lock *lock);
48 static void nlmsvc_freegrantargs(struct nlm_rqst *call);
49 static const struct rpc_call_ops nlmsvc_grant_ops;
50
51 /*
52 * The list of blocked locks to retry
53 */
54 static LIST_HEAD(nlm_blocked);
55 static DEFINE_SPINLOCK(nlm_blocked_lock);
56
57 #if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
58 static 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 */
89 static void
90 nlmsvc_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
120 static 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 */
130 static inline void
131 nlmsvc_remove_block(struct nlm_block *block)
132 {
133 spin_lock(&nlm_blocked_lock);
134 if (!list_empty(&block->b_list)) {
135 list_del_init(&block->b_list);
136 spin_unlock(&nlm_blocked_lock);
137 nlmsvc_release_block(block);
138 return;
139 }
140 spin_unlock(&nlm_blocked_lock);
141 }
142
143 /*
144 * Find a block for a given lock
145 */
146 static struct nlm_block *
147 nlmsvc_lookup_block(struct nlm_file *file, struct nlm_lock *lock)
148 {
149 struct nlm_block *block;
150 struct file_lock *fl;
151
152 dprintk("lockd: nlmsvc_lookup_block f=%p pd=%d %Ld-%Ld ty=%d\n",
153 file, lock->fl.c.flc_pid,
154 (long long)lock->fl.fl_start,
155 (long long)lock->fl.fl_end,
156 lock->fl.c.flc_type);
157 spin_lock(&nlm_blocked_lock);
158 list_for_each_entry(block, &nlm_blocked, b_list) {
159 fl = &block->b_call->a_args.lock.fl;
160 dprintk("lockd: check f=%p pd=%d %Ld-%Ld ty=%d cookie=%s\n",
161 block->b_file, fl->c.flc_pid,
162 (long long)fl->fl_start,
163 (long long)fl->fl_end, fl->c.flc_type,
164 nlmdbg_cookie2a(&block->b_call->a_args.cookie));
165 if (block->b_file == file && nlm_compare_locks(fl, &lock->fl)) {
166 kref_get(&block->b_count);
167 spin_unlock(&nlm_blocked_lock);
168 return block;
169 }
170 }
171 spin_unlock(&nlm_blocked_lock);
172
173 return NULL;
174 }
175
176 static inline int nlm_cookie_match(struct nlm_cookie *a, struct nlm_cookie *b)
177 {
178 if (a->len != b->len)
179 return 0;
180 if (memcmp(a->data, b->data, a->len))
181 return 0;
182 return 1;
183 }
184
185 /*
186 * Find a block with a given NLM cookie.
187 */
188 static inline struct nlm_block *
189 nlmsvc_find_block(struct nlm_cookie *cookie)
190 {
191 struct nlm_block *block;
192
193 spin_lock(&nlm_blocked_lock);
194 list_for_each_entry(block, &nlm_blocked, b_list) {
195 if (nlm_cookie_match(&block->b_call->a_args.cookie,cookie))
196 goto found;
197 }
198 spin_unlock(&nlm_blocked_lock);
199
200 return NULL;
201
202 found:
203 dprintk("nlmsvc_find_block(%s): block=%p\n", nlmdbg_cookie2a(cookie), block);
204 kref_get(&block->b_count);
205 spin_unlock(&nlm_blocked_lock);
206 return block;
207 }
208
209 /*
210 * Create a block and initialize it.
211 *
212 * Note: we explicitly set the cookie of the grant reply to that of
213 * the blocked lock request. The spec explicitly mentions that the client
214 * should _not_ rely on the callback containing the same cookie as the
215 * request, but (as I found out later) that's because some implementations
216 * do just this. Never mind the standards comittees, they support our
217 * logging industries.
218 *
219 * 10 years later: I hope we can safely ignore these old and broken
220 * clients by now. Let's fix this so we can uniquely identify an incoming
221 * GRANTED_RES message by cookie, without having to rely on the client's IP
222 * address. --okir
223 */
224 static struct nlm_block *
225 nlmsvc_create_block(struct svc_rqst *rqstp, struct nlm_host *host,
226 struct nlm_file *file, struct nlm_lock *lock,
227 struct nlm_cookie *cookie)
228 {
229 struct nlm_block *block;
230 struct nlm_rqst *call = NULL;
231
232 call = nlm_alloc_call(host);
233 if (call == NULL)
234 return NULL;
235
236 /* Allocate memory for block, and initialize arguments */
237 block = kzalloc(sizeof(*block), GFP_KERNEL);
238 if (block == NULL)
239 goto failed;
240 kref_init(&block->b_count);
241 INIT_LIST_HEAD(&block->b_list);
242 INIT_LIST_HEAD(&block->b_flist);
243
244 if (!nlmsvc_setgrantargs(call, lock))
245 goto failed_free;
246
247 /* Set notifier function for VFS, and init args */
248 call->a_args.lock.fl.c.flc_flags |= FL_SLEEP;
249 call->a_args.lock.fl.fl_lmops = &nlmsvc_lock_operations;
250 nlmclnt_next_cookie(&call->a_args.cookie);
251
252 dprintk("lockd: created block %p...\n", block);
253
254 /* Create and initialize the block */
255 block->b_daemon = rqstp->rq_server;
256 block->b_host = host;
257 block->b_file = file;
258 file->f_count++;
259
260 /* Add to file's list of blocks */
261 list_add(&block->b_flist, &file->f_blocks);
262
263 /* Set up RPC arguments for callback */
264 block->b_call = call;
265 call->a_flags = RPC_TASK_ASYNC;
266 call->a_block = block;
267
268 return block;
269
270 failed_free:
271 kfree(block);
272 failed:
273 nlmsvc_release_call(call);
274 return NULL;
275 }
276
277 /*
278 * Delete a block.
279 * It is the caller's responsibility to check whether the file
280 * can be closed hereafter.
281 */
282 static int nlmsvc_unlink_block(struct nlm_block *block)
283 {
284 int status;
285 dprintk("lockd: unlinking block %p...\n", block);
286
287 /* Remove block from list */
288 status = locks_delete_block(&block->b_call->a_args.lock.fl);
289 nlmsvc_remove_block(block);
290 return status;
291 }
292
293 static void nlmsvc_free_block(struct kref *kref)
294 {
295 struct nlm_block *block = container_of(kref, struct nlm_block, b_count);
296 struct nlm_file *file = block->b_file;
297
298 dprintk("lockd: freeing block %p...\n", block);
299
300 /* Remove block from file's list of blocks */
301 list_del_init(&block->b_flist);
302 mutex_unlock(&file->f_mutex);
303
304 nlmsvc_freegrantargs(block->b_call);
305 nlmsvc_release_call(block->b_call);
306 nlm_release_file(block->b_file);
307 kfree(block);
308 }
309
310 static void nlmsvc_release_block(struct nlm_block *block)
311 {
312 if (block != NULL)
313 kref_put_mutex(&block->b_count, nlmsvc_free_block, &block->b_file->f_mutex);
314 }
315
316 /*
317 * Loop over all blocks and delete blocks held by
318 * a matching host.
319 */
320 void nlmsvc_traverse_blocks(struct nlm_host *host,
321 struct nlm_file *file,
322 nlm_host_match_fn_t match)
323 {
324 struct nlm_block *block, *next;
325
326 restart:
327 mutex_lock(&file->f_mutex);
328 spin_lock(&nlm_blocked_lock);
329 list_for_each_entry_safe(block, next, &file->f_blocks, b_flist) {
330 if (!match(block->b_host, host))
331 continue;
332 /* Do not destroy blocks that are not on
333 * the global retry list - why? */
334 if (list_empty(&block->b_list))
335 continue;
336 kref_get(&block->b_count);
337 spin_unlock(&nlm_blocked_lock);
338 mutex_unlock(&file->f_mutex);
339 nlmsvc_unlink_block(block);
340 nlmsvc_release_block(block);
341 goto restart;
342 }
343 spin_unlock(&nlm_blocked_lock);
344 mutex_unlock(&file->f_mutex);
345 }
346
347 static struct nlm_lockowner *
348 nlmsvc_get_lockowner(struct nlm_lockowner *lockowner)
349 {
350 refcount_inc(&lockowner->count);
351 return lockowner;
352 }
353
354 void nlmsvc_put_lockowner(struct nlm_lockowner *lockowner)
355 {
356 if (!refcount_dec_and_lock(&lockowner->count, &lockowner->host->h_lock))
357 return;
358 list_del(&lockowner->list);
359 spin_unlock(&lockowner->host->h_lock);
360 nlmsvc_release_host(lockowner->host);
361 kfree(lockowner);
362 }
363
364 static struct nlm_lockowner *__nlmsvc_find_lockowner(struct nlm_host *host, pid_t pid)
365 {
366 struct nlm_lockowner *lockowner;
367 list_for_each_entry(lockowner, &host->h_lockowners, list) {
368 if (lockowner->pid != pid)
369 continue;
370 return nlmsvc_get_lockowner(lockowner);
371 }
372 return NULL;
373 }
374
375 static struct nlm_lockowner *nlmsvc_find_lockowner(struct nlm_host *host, pid_t pid)
376 {
377 struct nlm_lockowner *res, *new = NULL;
378
379 spin_lock(&host->h_lock);
380 res = __nlmsvc_find_lockowner(host, pid);
381
382 if (res == NULL) {
383 spin_unlock(&host->h_lock);
384 new = kmalloc(sizeof(*res), GFP_KERNEL);
385 spin_lock(&host->h_lock);
386 res = __nlmsvc_find_lockowner(host, pid);
387 if (res == NULL && new != NULL) {
388 res = new;
389 /* fs/locks.c will manage the refcount through lock_ops */
390 refcount_set(&new->count, 1);
391 new->pid = pid;
392 new->host = nlm_get_host(host);
393 list_add(&new->list, &host->h_lockowners);
394 new = NULL;
395 }
396 }
397
398 spin_unlock(&host->h_lock);
399 kfree(new);
400 return res;
401 }
402
403 void
404 nlmsvc_release_lockowner(struct nlm_lock *lock)
405 {
406 if (lock->fl.c.flc_owner)
407 nlmsvc_put_lockowner(lock->fl.c.flc_owner);
408 }
409
410 void nlmsvc_locks_init_private(struct file_lock *fl, struct nlm_host *host,
411 pid_t pid)
412 {
413 fl->c.flc_owner = nlmsvc_find_lockowner(host, pid);
414 }
415
416 /*
417 * Initialize arguments for GRANTED call. The nlm_rqst structure
418 * has been cleared already.
419 */
420 static int nlmsvc_setgrantargs(struct nlm_rqst *call, struct nlm_lock *lock)
421 {
422 locks_copy_lock(&call->a_args.lock.fl, &lock->fl);
423 memcpy(&call->a_args.lock.fh, &lock->fh, sizeof(call->a_args.lock.fh));
424 call->a_args.lock.caller = utsname()->nodename;
425 call->a_args.lock.oh.len = lock->oh.len;
426
427 /* set default data area */
428 call->a_args.lock.oh.data = call->a_owner;
429 call->a_args.lock.svid = ((struct nlm_lockowner *) lock->fl.c.flc_owner)->pid;
430
431 if (lock->oh.len > NLMCLNT_OHSIZE) {
432 void *data = kmalloc(lock->oh.len, GFP_KERNEL);
433 if (!data)
434 return 0;
435 call->a_args.lock.oh.data = (u8 *) data;
436 }
437
438 memcpy(call->a_args.lock.oh.data, lock->oh.data, lock->oh.len);
439 return 1;
440 }
441
442 static void nlmsvc_freegrantargs(struct nlm_rqst *call)
443 {
444 if (call->a_args.lock.oh.data != call->a_owner)
445 kfree(call->a_args.lock.oh.data);
446
447 locks_release_private(&call->a_args.lock.fl);
448 }
449
450 /*
451 * Deferred lock request handling for non-blocking lock
452 */
453 static __be32
454 nlmsvc_defer_lock_rqst(struct svc_rqst *rqstp, struct nlm_block *block)
455 {
456 __be32 status = nlm_lck_denied_nolocks;
457
458 block->b_flags |= B_QUEUED;
459
460 nlmsvc_insert_block(block, NLM_TIMEOUT);
461
462 block->b_cache_req = &rqstp->rq_chandle;
463 if (rqstp->rq_chandle.defer) {
464 block->b_deferred_req =
465 rqstp->rq_chandle.defer(block->b_cache_req);
466 if (block->b_deferred_req != NULL)
467 status = nlm_drop_reply;
468 }
469 dprintk("lockd: nlmsvc_defer_lock_rqst block %p flags %d status %d\n",
470 block, block->b_flags, ntohl(status));
471
472 return status;
473 }
474
475 /*
476 * Attempt to establish a lock, and if it can't be granted, block it
477 * if required.
478 */
479 __be32
480 nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file,
481 struct nlm_host *host, struct nlm_lock *lock, int wait,
482 struct nlm_cookie *cookie, int reclaim)
483 {
484 struct inode *inode = nlmsvc_file_inode(file);
485 struct nlm_block *block = NULL;
486 int error;
487 int mode;
488 int async_block = 0;
489 __be32 ret;
490
491 dprintk("lockd: nlmsvc_lock(%s/%ld, ty=%d, pi=%d, %Ld-%Ld, bl=%d)\n",
492 inode->i_sb->s_id, inode->i_ino,
493 lock->fl.c.flc_type,
494 lock->fl.c.flc_pid,
495 (long long)lock->fl.fl_start,
496 (long long)lock->fl.fl_end,
497 wait);
498
499 if (!exportfs_lock_op_is_async(inode->i_sb->s_export_op)) {
500 async_block = wait;
501 wait = 0;
502 }
503
504 /* Lock file against concurrent access */
505 mutex_lock(&file->f_mutex);
506 /* Get existing block (in case client is busy-waiting)
507 * or create new block
508 */
509 block = nlmsvc_lookup_block(file, lock);
510 if (block == NULL) {
511 block = nlmsvc_create_block(rqstp, host, file, lock, cookie);
512 ret = nlm_lck_denied_nolocks;
513 if (block == NULL)
514 goto out;
515 lock = &block->b_call->a_args.lock;
516 } else
517 lock->fl.c.flc_flags &= ~FL_SLEEP;
518
519 if (block->b_flags & B_QUEUED) {
520 dprintk("lockd: nlmsvc_lock deferred block %p flags %d\n",
521 block, block->b_flags);
522 if (block->b_granted) {
523 nlmsvc_unlink_block(block);
524 ret = nlm_granted;
525 goto out;
526 }
527 if (block->b_flags & B_TIMED_OUT) {
528 nlmsvc_unlink_block(block);
529 ret = nlm_lck_denied;
530 goto out;
531 }
532 ret = nlm_drop_reply;
533 goto out;
534 }
535
536 if (locks_in_grace(SVC_NET(rqstp)) && !reclaim) {
537 ret = nlm_lck_denied_grace_period;
538 goto out;
539 }
540 if (reclaim && !locks_in_grace(SVC_NET(rqstp))) {
541 ret = nlm_lck_denied_grace_period;
542 goto out;
543 }
544
545 spin_lock(&nlm_blocked_lock);
546 /*
547 * If this is a lock request for an already pending
548 * lock request we return nlm_lck_blocked without calling
549 * vfs_lock_file() again. Otherwise we have two pending
550 * requests on the underlaying ->lock() implementation but
551 * only one nlm_block to being granted by lm_grant().
552 */
553 if (exportfs_lock_op_is_async(inode->i_sb->s_export_op) &&
554 !list_empty(&block->b_list)) {
555 spin_unlock(&nlm_blocked_lock);
556 ret = nlm_lck_blocked;
557 goto out;
558 }
559
560 /* Append to list of blocked */
561 nlmsvc_insert_block_locked(block, NLM_NEVER);
562 spin_unlock(&nlm_blocked_lock);
563
564 if (!wait)
565 lock->fl.c.flc_flags &= ~FL_SLEEP;
566 mode = lock_to_openmode(&lock->fl);
567 error = vfs_lock_file(file->f_file[mode], F_SETLK, &lock->fl, NULL);
568 lock->fl.c.flc_flags &= ~FL_SLEEP;
569
570 dprintk("lockd: vfs_lock_file returned %d\n", error);
571 switch (error) {
572 case 0:
573 nlmsvc_remove_block(block);
574 ret = nlm_granted;
575 goto out;
576 case -EAGAIN:
577 if (!wait)
578 nlmsvc_remove_block(block);
579 ret = async_block ? nlm_lck_blocked : nlm_lck_denied;
580 goto out;
581 case FILE_LOCK_DEFERRED:
582 if (wait)
583 break;
584 /* Filesystem lock operation is in progress
585 Add it to the queue waiting for callback */
586 ret = nlmsvc_defer_lock_rqst(rqstp, block);
587 goto out;
588 case -EDEADLK:
589 nlmsvc_remove_block(block);
590 ret = nlm_deadlock;
591 goto out;
592 default: /* includes ENOLCK */
593 nlmsvc_remove_block(block);
594 ret = nlm_lck_denied_nolocks;
595 goto out;
596 }
597
598 ret = nlm_lck_blocked;
599 out:
600 mutex_unlock(&file->f_mutex);
601 nlmsvc_release_block(block);
602 dprintk("lockd: nlmsvc_lock returned %u\n", ret);
603 return ret;
604 }
605
606 /*
607 * Test for presence of a conflicting lock.
608 */
609 __be32
610 nlmsvc_testlock(struct svc_rqst *rqstp, struct nlm_file *file,
611 struct nlm_host *host, struct nlm_lock *lock,
612 struct nlm_lock *conflock, struct nlm_cookie *cookie)
613 {
614 int error;
615 int mode;
616 __be32 ret;
617
618 dprintk("lockd: nlmsvc_testlock(%s/%ld, ty=%d, %Ld-%Ld)\n",
619 nlmsvc_file_inode(file)->i_sb->s_id,
620 nlmsvc_file_inode(file)->i_ino,
621 lock->fl.c.flc_type,
622 (long long)lock->fl.fl_start,
623 (long long)lock->fl.fl_end);
624
625 if (locks_in_grace(SVC_NET(rqstp))) {
626 ret = nlm_lck_denied_grace_period;
627 goto out;
628 }
629
630 mode = lock_to_openmode(&lock->fl);
631 error = vfs_test_lock(file->f_file[mode], &lock->fl);
632 if (error) {
633 /* We can't currently deal with deferred test requests */
634 if (error == FILE_LOCK_DEFERRED)
635 WARN_ON_ONCE(1);
636
637 ret = nlm_lck_denied_nolocks;
638 goto out;
639 }
640
641 if (lock->fl.c.flc_type == F_UNLCK) {
642 ret = nlm_granted;
643 goto out;
644 }
645
646 dprintk("lockd: conflicting lock(ty=%d, %Ld-%Ld)\n",
647 lock->fl.c.flc_type, (long long)lock->fl.fl_start,
648 (long long)lock->fl.fl_end);
649 conflock->caller = "somehost"; /* FIXME */
650 conflock->len = strlen(conflock->caller);
651 conflock->oh.len = 0; /* don't return OH info */
652 conflock->svid = lock->fl.c.flc_pid;
653 conflock->fl.c.flc_type = lock->fl.c.flc_type;
654 conflock->fl.fl_start = lock->fl.fl_start;
655 conflock->fl.fl_end = lock->fl.fl_end;
656 locks_release_private(&lock->fl);
657
658 ret = nlm_lck_denied;
659 out:
660 return ret;
661 }
662
663 /*
664 * Remove a lock.
665 * This implies a CANCEL call: We send a GRANT_MSG, the client replies
666 * with a GRANT_RES call which gets lost, and calls UNLOCK immediately
667 * afterwards. In this case the block will still be there, and hence
668 * must be removed.
669 */
670 __be32
671 nlmsvc_unlock(struct net *net, struct nlm_file *file, struct nlm_lock *lock)
672 {
673 int error = 0;
674
675 dprintk("lockd: nlmsvc_unlock(%s/%ld, pi=%d, %Ld-%Ld)\n",
676 nlmsvc_file_inode(file)->i_sb->s_id,
677 nlmsvc_file_inode(file)->i_ino,
678 lock->fl.c.flc_pid,
679 (long long)lock->fl.fl_start,
680 (long long)lock->fl.fl_end);
681
682 /* First, cancel any lock that might be there */
683 nlmsvc_cancel_blocked(net, file, lock);
684
685 lock->fl.c.flc_type = F_UNLCK;
686 lock->fl.c.flc_file = file->f_file[O_RDONLY];
687 if (lock->fl.c.flc_file)
688 error = vfs_lock_file(lock->fl.c.flc_file, F_SETLK,
689 &lock->fl, NULL);
690 lock->fl.c.flc_file = file->f_file[O_WRONLY];
691 if (lock->fl.c.flc_file)
692 error |= vfs_lock_file(lock->fl.c.flc_file, F_SETLK,
693 &lock->fl, NULL);
694
695 return (error < 0)? nlm_lck_denied_nolocks : nlm_granted;
696 }
697
698 /*
699 * Cancel a previously blocked request.
700 *
701 * A cancel request always overrides any grant that may currently
702 * be in progress.
703 * The calling procedure must check whether the file can be closed.
704 */
705 __be32
706 nlmsvc_cancel_blocked(struct net *net, struct nlm_file *file, struct nlm_lock *lock)
707 {
708 struct nlm_block *block;
709 int status = 0;
710 int mode;
711
712 dprintk("lockd: nlmsvc_cancel(%s/%ld, pi=%d, %Ld-%Ld)\n",
713 nlmsvc_file_inode(file)->i_sb->s_id,
714 nlmsvc_file_inode(file)->i_ino,
715 lock->fl.c.flc_pid,
716 (long long)lock->fl.fl_start,
717 (long long)lock->fl.fl_end);
718
719 if (locks_in_grace(net))
720 return nlm_lck_denied_grace_period;
721
722 mutex_lock(&file->f_mutex);
723 block = nlmsvc_lookup_block(file, lock);
724 mutex_unlock(&file->f_mutex);
725 if (block != NULL) {
726 struct file_lock *fl = &block->b_call->a_args.lock.fl;
727
728 mode = lock_to_openmode(fl);
729 vfs_cancel_lock(block->b_file->f_file[mode], fl);
730 status = nlmsvc_unlink_block(block);
731 nlmsvc_release_block(block);
732 }
733 return status ? nlm_lck_denied : nlm_granted;
734 }
735
736 /*
737 * This is a callback from the filesystem for VFS file lock requests.
738 * It will be used if lm_grant is defined and the filesystem can not
739 * respond to the request immediately.
740 * For SETLK or SETLKW request it will get the local posix lock.
741 * In all cases it will move the block to the head of nlm_blocked q where
742 * nlmsvc_retry_blocked() can send back a reply for SETLKW or revisit the
743 * deferred rpc for GETLK and SETLK.
744 */
745 static void
746 nlmsvc_update_deferred_block(struct nlm_block *block, int result)
747 {
748 block->b_flags |= B_GOT_CALLBACK;
749 if (result == 0)
750 block->b_granted = 1;
751 else
752 block->b_flags |= B_TIMED_OUT;
753 }
754
755 static int nlmsvc_grant_deferred(struct file_lock *fl, int result)
756 {
757 struct nlm_block *block;
758 int rc = -ENOENT;
759
760 spin_lock(&nlm_blocked_lock);
761 list_for_each_entry(block, &nlm_blocked, b_list) {
762 if (nlm_compare_locks(&block->b_call->a_args.lock.fl, fl)) {
763 dprintk("lockd: nlmsvc_notify_blocked block %p flags %d\n",
764 block, block->b_flags);
765 if (block->b_flags & B_QUEUED) {
766 if (block->b_flags & B_TIMED_OUT) {
767 rc = -ENOLCK;
768 break;
769 }
770 nlmsvc_update_deferred_block(block, result);
771 } else if (result == 0)
772 block->b_granted = 1;
773
774 nlmsvc_insert_block_locked(block, 0);
775 svc_wake_up(block->b_daemon);
776 rc = 0;
777 break;
778 }
779 }
780 spin_unlock(&nlm_blocked_lock);
781 if (rc == -ENOENT)
782 printk(KERN_WARNING "lockd: grant for unknown block\n");
783 return rc;
784 }
785
786 /*
787 * Unblock a blocked lock request. This is a callback invoked from the
788 * VFS layer when a lock on which we blocked is removed.
789 *
790 * This function doesn't grant the blocked lock instantly, but rather moves
791 * the block to the head of nlm_blocked where it can be picked up by lockd.
792 */
793 static void
794 nlmsvc_notify_blocked(struct file_lock *fl)
795 {
796 struct nlm_block *block;
797
798 dprintk("lockd: VFS unblock notification for block %p\n", fl);
799 spin_lock(&nlm_blocked_lock);
800 list_for_each_entry(block, &nlm_blocked, b_list) {
801 if (nlm_compare_locks(&block->b_call->a_args.lock.fl, fl)) {
802 nlmsvc_insert_block_locked(block, 0);
803 spin_unlock(&nlm_blocked_lock);
804 svc_wake_up(block->b_daemon);
805 return;
806 }
807 }
808 spin_unlock(&nlm_blocked_lock);
809 printk(KERN_WARNING "lockd: notification for unknown block!\n");
810 }
811
812 static fl_owner_t nlmsvc_get_owner(fl_owner_t owner)
813 {
814 return nlmsvc_get_lockowner(owner);
815 }
816
817 static void nlmsvc_put_owner(fl_owner_t owner)
818 {
819 nlmsvc_put_lockowner(owner);
820 }
821
822 const struct lock_manager_operations nlmsvc_lock_operations = {
823 .lm_notify = nlmsvc_notify_blocked,
824 .lm_grant = nlmsvc_grant_deferred,
825 .lm_get_owner = nlmsvc_get_owner,
826 .lm_put_owner = nlmsvc_put_owner,
827 };
828
829 /*
830 * Try to claim a lock that was previously blocked.
831 *
832 * Note that we use both the RPC_GRANTED_MSG call _and_ an async
833 * RPC thread when notifying the client. This seems like overkill...
834 * Here's why:
835 * - we don't want to use a synchronous RPC thread, otherwise
836 * we might find ourselves hanging on a dead portmapper.
837 * - Some lockd implementations (e.g. HP) don't react to
838 * RPC_GRANTED calls; they seem to insist on RPC_GRANTED_MSG calls.
839 */
840 static void
841 nlmsvc_grant_blocked(struct nlm_block *block)
842 {
843 struct nlm_file *file = block->b_file;
844 struct nlm_lock *lock = &block->b_call->a_args.lock;
845 int mode;
846 int error;
847 loff_t fl_start, fl_end;
848
849 dprintk("lockd: grant blocked lock %p\n", block);
850
851 kref_get(&block->b_count);
852
853 /* Unlink block request from list */
854 nlmsvc_unlink_block(block);
855
856 /* If b_granted is true this means we've been here before.
857 * Just retry the grant callback, possibly refreshing the RPC
858 * binding */
859 if (block->b_granted) {
860 nlm_rebind_host(block->b_host);
861 goto callback;
862 }
863
864 /* Try the lock operation again */
865 /* vfs_lock_file() can mangle fl_start and fl_end, but we need
866 * them unchanged for the GRANT_MSG
867 */
868 lock->fl.c.flc_flags |= FL_SLEEP;
869 fl_start = lock->fl.fl_start;
870 fl_end = lock->fl.fl_end;
871 mode = lock_to_openmode(&lock->fl);
872 error = vfs_lock_file(file->f_file[mode], F_SETLK, &lock->fl, NULL);
873 lock->fl.c.flc_flags &= ~FL_SLEEP;
874 lock->fl.fl_start = fl_start;
875 lock->fl.fl_end = fl_end;
876
877 switch (error) {
878 case 0:
879 break;
880 case FILE_LOCK_DEFERRED:
881 dprintk("lockd: lock still blocked error %d\n", error);
882 nlmsvc_insert_block(block, NLM_NEVER);
883 nlmsvc_release_block(block);
884 return;
885 default:
886 printk(KERN_WARNING "lockd: unexpected error %d in %s!\n",
887 -error, __func__);
888 nlmsvc_insert_block(block, 10 * HZ);
889 nlmsvc_release_block(block);
890 return;
891 }
892
893 callback:
894 /* Lock was granted by VFS. */
895 dprintk("lockd: GRANTing blocked lock.\n");
896 block->b_granted = 1;
897
898 /* keep block on the list, but don't reattempt until the RPC
899 * completes or the submission fails
900 */
901 nlmsvc_insert_block(block, NLM_NEVER);
902
903 /* Call the client -- use a soft RPC task since nlmsvc_retry_blocked
904 * will queue up a new one if this one times out
905 */
906 error = nlm_async_call(block->b_call, NLMPROC_GRANTED_MSG,
907 &nlmsvc_grant_ops);
908
909 /* RPC submission failed, wait a bit and retry */
910 if (error < 0)
911 nlmsvc_insert_block(block, 10 * HZ);
912 }
913
914 /*
915 * This is the callback from the RPC layer when the NLM_GRANTED_MSG
916 * RPC call has succeeded or timed out.
917 * Like all RPC callbacks, it is invoked by the rpciod process, so it
918 * better not sleep. Therefore, we put the blocked lock on the nlm_blocked
919 * chain once more in order to have it removed by lockd itself (which can
920 * then sleep on the file semaphore without disrupting e.g. the nfs client).
921 */
922 static void nlmsvc_grant_callback(struct rpc_task *task, void *data)
923 {
924 struct nlm_rqst *call = data;
925 struct nlm_block *block = call->a_block;
926 unsigned long timeout;
927
928 dprintk("lockd: GRANT_MSG RPC callback\n");
929
930 spin_lock(&nlm_blocked_lock);
931 /* if the block is not on a list at this point then it has
932 * been invalidated. Don't try to requeue it.
933 *
934 * FIXME: it's possible that the block is removed from the list
935 * after this check but before the nlmsvc_insert_block. In that
936 * case it will be added back. Perhaps we need better locking
937 * for nlm_blocked?
938 */
939 if (list_empty(&block->b_list))
940 goto out;
941
942 /* Technically, we should down the file semaphore here. Since we
943 * move the block towards the head of the queue only, no harm
944 * can be done, though. */
945 if (task->tk_status < 0) {
946 /* RPC error: Re-insert for retransmission */
947 timeout = 10 * HZ;
948 } else {
949 /* Call was successful, now wait for client callback */
950 timeout = 60 * HZ;
951 }
952 nlmsvc_insert_block_locked(block, timeout);
953 svc_wake_up(block->b_daemon);
954 out:
955 spin_unlock(&nlm_blocked_lock);
956 }
957
958 /*
959 * FIXME: nlmsvc_release_block() grabs a mutex. This is not allowed for an
960 * .rpc_release rpc_call_op
961 */
962 static void nlmsvc_grant_release(void *data)
963 {
964 struct nlm_rqst *call = data;
965 nlmsvc_release_block(call->a_block);
966 }
967
968 static const struct rpc_call_ops nlmsvc_grant_ops = {
969 .rpc_call_done = nlmsvc_grant_callback,
970 .rpc_release = nlmsvc_grant_release,
971 };
972
973 /*
974 * We received a GRANT_RES callback. Try to find the corresponding
975 * block.
976 */
977 void
978 nlmsvc_grant_reply(struct nlm_cookie *cookie, __be32 status)
979 {
980 struct nlm_block *block;
981 struct file_lock *fl;
982 int error;
983
984 dprintk("grant_reply: looking for cookie %x, s=%d \n",
985 *(unsigned int *)(cookie->data), status);
986 if (!(block = nlmsvc_find_block(cookie)))
987 return;
988
989 switch (status) {
990 case nlm_lck_denied_grace_period:
991 /* Try again in a couple of seconds */
992 nlmsvc_insert_block(block, 10 * HZ);
993 break;
994 case nlm_lck_denied:
995 /* Client doesn't want it, just unlock it */
996 nlmsvc_unlink_block(block);
997 fl = &block->b_call->a_args.lock.fl;
998 fl->c.flc_type = F_UNLCK;
999 error = vfs_lock_file(fl->c.flc_file, F_SETLK, fl, NULL);
1000 if (error)
1001 pr_warn("lockd: unable to unlock lock rejected by client!\n");
1002 break;
1003 default:
1004 /*
1005 * Either it was accepted or the status makes no sense
1006 * just unlink it either way.
1007 */
1008 nlmsvc_unlink_block(block);
1009 }
1010 nlmsvc_release_block(block);
1011 }
1012
1013 /* Helper function to handle retry of a deferred block.
1014 * If it is a blocking lock, call grant_blocked.
1015 * For a non-blocking lock or test lock, revisit the request.
1016 */
1017 static void
1018 retry_deferred_block(struct nlm_block *block)
1019 {
1020 if (!(block->b_flags & B_GOT_CALLBACK))
1021 block->b_flags |= B_TIMED_OUT;
1022 nlmsvc_insert_block(block, NLM_TIMEOUT);
1023 dprintk("revisit block %p flags %d\n", block, block->b_flags);
1024 if (block->b_deferred_req) {
1025 block->b_deferred_req->revisit(block->b_deferred_req, 0);
1026 block->b_deferred_req = NULL;
1027 }
1028 }
1029
1030 /*
1031 * Retry all blocked locks that have been notified. This is where lockd
1032 * picks up locks that can be granted, or grant notifications that must
1033 * be retransmitted.
1034 */
1035 void
1036 nlmsvc_retry_blocked(struct svc_rqst *rqstp)
1037 {
1038 unsigned long timeout = MAX_SCHEDULE_TIMEOUT;
1039 struct nlm_block *block;
1040
1041 spin_lock(&nlm_blocked_lock);
1042 while (!list_empty(&nlm_blocked) && !svc_thread_should_stop(rqstp)) {
1043 block = list_entry(nlm_blocked.next, struct nlm_block, b_list);
1044
1045 if (block->b_when == NLM_NEVER)
1046 break;
1047 if (time_after(block->b_when, jiffies)) {
1048 timeout = block->b_when - jiffies;
1049 break;
1050 }
1051 spin_unlock(&nlm_blocked_lock);
1052
1053 dprintk("nlmsvc_retry_blocked(%p, when=%ld)\n",
1054 block, block->b_when);
1055 if (block->b_flags & B_QUEUED) {
1056 dprintk("nlmsvc_retry_blocked delete block (%p, granted=%d, flags=%d)\n",
1057 block, block->b_granted, block->b_flags);
1058 retry_deferred_block(block);
1059 } else
1060 nlmsvc_grant_blocked(block);
1061 spin_lock(&nlm_blocked_lock);
1062 }
1063 spin_unlock(&nlm_blocked_lock);
1064
1065 if (timeout < MAX_SCHEDULE_TIMEOUT)
1066 mod_timer(&nlmsvc_retry, jiffies + timeout);
1067 }
1068
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