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