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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 | |
42 | static void nlmsvc_release_block(struct nlm_block *block); |
43 | static void nlmsvc_insert_block(struct nlm_block *block, unsigned long); |
44 | static void nlmsvc_remove_block(struct nlm_block *block); |
45 | |
46 | static int nlmsvc_setgrantargs(struct nlm_rqst *call, struct nlm_lock *lock); |
47 | static void nlmsvc_freegrantargs(struct nlm_rqst *call); |
48 | static const struct rpc_call_ops nlmsvc_grant_ops; |
49 | static const char *nlmdbg_cookie2a(const struct nlm_cookie *cookie); |
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 | /* |
58 | * Insert a blocked lock into the global list |
59 | */ |
60 | static void |
61 | nlmsvc_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 | |
91 | static 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 | */ |
101 | static inline void |
102 | nlmsvc_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 | */ |
115 | static struct nlm_block * |
116 | nlmsvc_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 | |
141 | static 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 | */ |
153 | static inline struct nlm_block * |
154 | nlmsvc_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 | |
165 | found: |
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 | */ |
186 | static struct nlm_block * |
187 | nlmsvc_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 | |
234 | failed_free: |
235 | kfree(block); |
236 | failed: |
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 | */ |
246 | static 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 | |
257 | static 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 | |
276 | static 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 | */ |
286 | void 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 | |
292 | restart: |
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 | */ |
314 | static 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 | |
336 | static 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 | */ |
347 | static __be32 |
348 | nlmsvc_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 |
374 | nlmsvc_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); |
470 | out: |
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 |
481 | nlmsvc_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 | |
552 | conf_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; |
564 | out: |
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 |
578 | nlmsvc_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 |
606 | nlmsvc_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 fl_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 | */ |
643 | static void |
644 | nlmsvc_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 | |
658 | static 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 | */ |
697 | static void |
698 | nlmsvc_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 | |
716 | static 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 | |
721 | const struct lock_manager_operations nlmsvc_lock_operations = { |
722 | .fl_compare_owner = nlmsvc_same_owner, |
723 | .fl_notify = nlmsvc_notify_blocked, |
724 | .fl_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 | */ |
738 | static void |
739 | nlmsvc_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 | |
781 | callback: |
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 | */ |
810 | static 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); |
842 | out: |
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 | */ |
850 | static void nlmsvc_grant_release(void *data) |
851 | { |
852 | struct nlm_rqst *call = data; |
853 | nlmsvc_release_block(call->a_block); |
854 | } |
855 | |
856 | static 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 | */ |
865 | void |
866 | nlmsvc_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 | */ |
892 | static void |
893 | retry_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 | */ |
910 | unsigned long |
911 | nlmsvc_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 |
940 | static 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 |
967 |
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