1 /* AFS file locking support
2 *
3 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
4 * Written by David Howells (dhowells@redhat.com)
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License
8 * as published by the Free Software Foundation; either version
9 * 2 of the License, or (at your option) any later version.
10 */
11
12 #include "internal.h"
13
14 #define AFS_LOCK_GRANTED 0
15 #define AFS_LOCK_PENDING 1
16 #define AFS_LOCK_YOUR_TRY 2
17
18 struct workqueue_struct *afs_lock_manager;
19
20 static void afs_next_locker(struct afs_vnode *vnode, int error);
21 static void afs_fl_copy_lock(struct file_lock *new, struct file_lock *fl);
22 static void afs_fl_release_private(struct file_lock *fl);
23
24 static const struct file_lock_operations afs_lock_ops = {
25 .fl_copy_lock = afs_fl_copy_lock,
26 .fl_release_private = afs_fl_release_private,
27 };
28
afs_set_lock_state(struct afs_vnode * vnode,enum afs_lock_state state)29 static inline void afs_set_lock_state(struct afs_vnode *vnode, enum afs_lock_state state)
30 {
31 _debug("STATE %u -> %u", vnode->lock_state, state);
32 vnode->lock_state = state;
33 }
34
35 /*
36 * if the callback is broken on this vnode, then the lock may now be available
37 */
afs_lock_may_be_available(struct afs_vnode * vnode)38 void afs_lock_may_be_available(struct afs_vnode *vnode)
39 {
40 _enter("{%x:%u}", vnode->fid.vid, vnode->fid.vnode);
41
42 spin_lock(&vnode->lock);
43 if (vnode->lock_state == AFS_VNODE_LOCK_WAITING_FOR_CB)
44 afs_next_locker(vnode, 0);
45 spin_unlock(&vnode->lock);
46 }
47
48 /*
49 * the lock will time out in 5 minutes unless we extend it, so schedule
50 * extension in a bit less than that time
51 */
afs_schedule_lock_extension(struct afs_vnode * vnode)52 static void __maybe_unused afs_schedule_lock_extension(struct afs_vnode *vnode)
53 {
54 queue_delayed_work(afs_lock_manager, &vnode->lock_work,
55 AFS_LOCKWAIT * HZ / 2);
56 }
57
58 /*
59 * grant one or more locks (readlocks are allowed to jump the queue if the
60 * first lock in the queue is itself a readlock)
61 * - the caller must hold the vnode lock
62 */
afs_grant_locks(struct afs_vnode * vnode)63 static void afs_grant_locks(struct afs_vnode *vnode)
64 {
65 struct file_lock *p, *_p;
66 bool exclusive = (vnode->lock_type == AFS_LOCK_WRITE);
67
68 list_for_each_entry_safe(p, _p, &vnode->pending_locks, fl_u.afs.link) {
69 if (!exclusive && p->fl_type == F_WRLCK)
70 continue;
71
72 list_move_tail(&p->fl_u.afs.link, &vnode->granted_locks);
73 p->fl_u.afs.state = AFS_LOCK_GRANTED;
74 wake_up(&p->fl_wait);
75 }
76 }
77
78 /*
79 * If an error is specified, reject every pending lock that matches the
80 * authentication and type of the lock we failed to get. If there are any
81 * remaining lockers, try to wake up one of them to have a go.
82 */
afs_next_locker(struct afs_vnode * vnode,int error)83 static void afs_next_locker(struct afs_vnode *vnode, int error)
84 {
85 struct file_lock *p, *_p, *next = NULL;
86 struct key *key = vnode->lock_key;
87 unsigned int fl_type = F_RDLCK;
88
89 _enter("");
90
91 if (vnode->lock_type == AFS_LOCK_WRITE)
92 fl_type = F_WRLCK;
93
94 list_for_each_entry_safe(p, _p, &vnode->pending_locks, fl_u.afs.link) {
95 if (error &&
96 p->fl_type == fl_type &&
97 afs_file_key(p->fl_file) == key) {
98 list_del_init(&p->fl_u.afs.link);
99 p->fl_u.afs.state = error;
100 wake_up(&p->fl_wait);
101 }
102
103 /* Select the next locker to hand off to. */
104 if (next &&
105 (next->fl_type == F_WRLCK || p->fl_type == F_RDLCK))
106 continue;
107 next = p;
108 }
109
110 vnode->lock_key = NULL;
111 key_put(key);
112
113 if (next) {
114 afs_set_lock_state(vnode, AFS_VNODE_LOCK_SETTING);
115 next->fl_u.afs.state = AFS_LOCK_YOUR_TRY;
116 wake_up(&next->fl_wait);
117 } else {
118 afs_set_lock_state(vnode, AFS_VNODE_LOCK_NONE);
119 }
120
121 _leave("");
122 }
123
124 /*
125 * Get a lock on a file
126 */
afs_set_lock(struct afs_vnode * vnode,struct key * key,afs_lock_type_t type)127 static int afs_set_lock(struct afs_vnode *vnode, struct key *key,
128 afs_lock_type_t type)
129 {
130 struct afs_fs_cursor fc;
131 int ret;
132
133 _enter("%s{%x:%u.%u},%x,%u",
134 vnode->volume->name,
135 vnode->fid.vid,
136 vnode->fid.vnode,
137 vnode->fid.unique,
138 key_serial(key), type);
139
140 ret = -ERESTARTSYS;
141 if (afs_begin_vnode_operation(&fc, vnode, key)) {
142 while (afs_select_fileserver(&fc)) {
143 fc.cb_break = afs_calc_vnode_cb_break(vnode);
144 afs_fs_set_lock(&fc, type);
145 }
146
147 afs_check_for_remote_deletion(&fc, fc.vnode);
148 afs_vnode_commit_status(&fc, vnode, fc.cb_break);
149 ret = afs_end_vnode_operation(&fc);
150 }
151
152 _leave(" = %d", ret);
153 return ret;
154 }
155
156 /*
157 * Extend a lock on a file
158 */
afs_extend_lock(struct afs_vnode * vnode,struct key * key)159 static int afs_extend_lock(struct afs_vnode *vnode, struct key *key)
160 {
161 struct afs_fs_cursor fc;
162 int ret;
163
164 _enter("%s{%x:%u.%u},%x",
165 vnode->volume->name,
166 vnode->fid.vid,
167 vnode->fid.vnode,
168 vnode->fid.unique,
169 key_serial(key));
170
171 ret = -ERESTARTSYS;
172 if (afs_begin_vnode_operation(&fc, vnode, key)) {
173 while (afs_select_current_fileserver(&fc)) {
174 fc.cb_break = afs_calc_vnode_cb_break(vnode);
175 afs_fs_extend_lock(&fc);
176 }
177
178 afs_check_for_remote_deletion(&fc, fc.vnode);
179 afs_vnode_commit_status(&fc, vnode, fc.cb_break);
180 ret = afs_end_vnode_operation(&fc);
181 }
182
183 _leave(" = %d", ret);
184 return ret;
185 }
186
187 /*
188 * Release a lock on a file
189 */
afs_release_lock(struct afs_vnode * vnode,struct key * key)190 static int afs_release_lock(struct afs_vnode *vnode, struct key *key)
191 {
192 struct afs_fs_cursor fc;
193 int ret;
194
195 _enter("%s{%x:%u.%u},%x",
196 vnode->volume->name,
197 vnode->fid.vid,
198 vnode->fid.vnode,
199 vnode->fid.unique,
200 key_serial(key));
201
202 ret = -ERESTARTSYS;
203 if (afs_begin_vnode_operation(&fc, vnode, key)) {
204 while (afs_select_current_fileserver(&fc)) {
205 fc.cb_break = afs_calc_vnode_cb_break(vnode);
206 afs_fs_release_lock(&fc);
207 }
208
209 afs_check_for_remote_deletion(&fc, fc.vnode);
210 afs_vnode_commit_status(&fc, vnode, fc.cb_break);
211 ret = afs_end_vnode_operation(&fc);
212 }
213
214 _leave(" = %d", ret);
215 return ret;
216 }
217
218 /*
219 * do work for a lock, including:
220 * - probing for a lock we're waiting on but didn't get immediately
221 * - extending a lock that's close to timing out
222 */
afs_lock_work(struct work_struct * work)223 void afs_lock_work(struct work_struct *work)
224 {
225 struct afs_vnode *vnode =
226 container_of(work, struct afs_vnode, lock_work.work);
227 struct key *key;
228 int ret;
229
230 _enter("{%x:%u}", vnode->fid.vid, vnode->fid.vnode);
231
232 spin_lock(&vnode->lock);
233
234 again:
235 _debug("wstate %u for %p", vnode->lock_state, vnode);
236 switch (vnode->lock_state) {
237 case AFS_VNODE_LOCK_NEED_UNLOCK:
238 _debug("unlock");
239 afs_set_lock_state(vnode, AFS_VNODE_LOCK_UNLOCKING);
240 spin_unlock(&vnode->lock);
241
242 /* attempt to release the server lock; if it fails, we just
243 * wait 5 minutes and it'll expire anyway */
244 ret = afs_release_lock(vnode, vnode->lock_key);
245 if (ret < 0)
246 printk(KERN_WARNING "AFS:"
247 " Failed to release lock on {%x:%x} error %d\n",
248 vnode->fid.vid, vnode->fid.vnode, ret);
249
250 spin_lock(&vnode->lock);
251 afs_next_locker(vnode, 0);
252 spin_unlock(&vnode->lock);
253 return;
254
255 /* If we've already got a lock, then it must be time to extend that
256 * lock as AFS locks time out after 5 minutes.
257 */
258 case AFS_VNODE_LOCK_GRANTED:
259 _debug("extend");
260
261 ASSERT(!list_empty(&vnode->granted_locks));
262
263 key = key_get(vnode->lock_key);
264 afs_set_lock_state(vnode, AFS_VNODE_LOCK_EXTENDING);
265 spin_unlock(&vnode->lock);
266
267 ret = afs_extend_lock(vnode, key); /* RPC */
268 key_put(key);
269
270 if (ret < 0)
271 pr_warning("AFS: Failed to extend lock on {%x:%x} error %d\n",
272 vnode->fid.vid, vnode->fid.vnode, ret);
273
274 spin_lock(&vnode->lock);
275
276 if (vnode->lock_state != AFS_VNODE_LOCK_EXTENDING)
277 goto again;
278 afs_set_lock_state(vnode, AFS_VNODE_LOCK_GRANTED);
279
280 if (ret != 0)
281 queue_delayed_work(afs_lock_manager, &vnode->lock_work,
282 HZ * 10);
283 spin_unlock(&vnode->lock);
284 _leave(" [ext]");
285 return;
286
287 /* If we're waiting for a callback to indicate lock release, we can't
288 * actually rely on this, so need to recheck at regular intervals. The
289 * problem is that the server might not notify us if the lock just
290 * expires (say because a client died) rather than being explicitly
291 * released.
292 */
293 case AFS_VNODE_LOCK_WAITING_FOR_CB:
294 _debug("retry");
295 afs_next_locker(vnode, 0);
296 spin_unlock(&vnode->lock);
297 return;
298
299 default:
300 /* Looks like a lock request was withdrawn. */
301 spin_unlock(&vnode->lock);
302 _leave(" [no]");
303 return;
304 }
305 }
306
307 /*
308 * pass responsibility for the unlocking of a vnode on the server to the
309 * manager thread, lest a pending signal in the calling thread interrupt
310 * AF_RXRPC
311 * - the caller must hold the vnode lock
312 */
afs_defer_unlock(struct afs_vnode * vnode)313 static void afs_defer_unlock(struct afs_vnode *vnode)
314 {
315 _enter("%u", vnode->lock_state);
316
317 if (list_empty(&vnode->granted_locks) &&
318 (vnode->lock_state == AFS_VNODE_LOCK_GRANTED ||
319 vnode->lock_state == AFS_VNODE_LOCK_EXTENDING)) {
320 cancel_delayed_work(&vnode->lock_work);
321
322 afs_set_lock_state(vnode, AFS_VNODE_LOCK_NEED_UNLOCK);
323 queue_delayed_work(afs_lock_manager, &vnode->lock_work, 0);
324 }
325 }
326
327 /*
328 * Check that our view of the file metadata is up to date and check to see
329 * whether we think that we have a locking permit.
330 */
afs_do_setlk_check(struct afs_vnode * vnode,struct key * key,afs_lock_type_t type,bool can_sleep)331 static int afs_do_setlk_check(struct afs_vnode *vnode, struct key *key,
332 afs_lock_type_t type, bool can_sleep)
333 {
334 afs_access_t access;
335 int ret;
336
337 /* Make sure we've got a callback on this file and that our view of the
338 * data version is up to date.
339 */
340 ret = afs_validate(vnode, key);
341 if (ret < 0)
342 return ret;
343
344 /* Check the permission set to see if we're actually going to be
345 * allowed to get a lock on this file.
346 */
347 ret = afs_check_permit(vnode, key, &access);
348 if (ret < 0)
349 return ret;
350
351 /* At a rough estimation, you need LOCK, WRITE or INSERT perm to
352 * read-lock a file and WRITE or INSERT perm to write-lock a file.
353 *
354 * We can't rely on the server to do this for us since if we want to
355 * share a read lock that we already have, we won't go the server.
356 */
357 if (type == AFS_LOCK_READ) {
358 if (!(access & (AFS_ACE_INSERT | AFS_ACE_WRITE | AFS_ACE_LOCK)))
359 return -EACCES;
360 if (vnode->status.lock_count == -1 && !can_sleep)
361 return -EAGAIN; /* Write locked */
362 } else {
363 if (!(access & (AFS_ACE_INSERT | AFS_ACE_WRITE)))
364 return -EACCES;
365 if (vnode->status.lock_count != 0 && !can_sleep)
366 return -EAGAIN; /* Locked */
367 }
368
369 return 0;
370 }
371
372 /*
373 * request a lock on a file on the server
374 */
afs_do_setlk(struct file * file,struct file_lock * fl)375 static int afs_do_setlk(struct file *file, struct file_lock *fl)
376 {
377 struct inode *inode = locks_inode(file);
378 struct afs_vnode *vnode = AFS_FS_I(inode);
379 afs_lock_type_t type;
380 struct key *key = afs_file_key(file);
381 int ret;
382
383 _enter("{%x:%u},%u", vnode->fid.vid, vnode->fid.vnode, fl->fl_type);
384
385 fl->fl_ops = &afs_lock_ops;
386 INIT_LIST_HEAD(&fl->fl_u.afs.link);
387 fl->fl_u.afs.state = AFS_LOCK_PENDING;
388
389 type = (fl->fl_type == F_RDLCK) ? AFS_LOCK_READ : AFS_LOCK_WRITE;
390
391 ret = afs_do_setlk_check(vnode, key, type, fl->fl_flags & FL_SLEEP);
392 if (ret < 0)
393 return ret;
394
395 spin_lock(&vnode->lock);
396 list_add_tail(&fl->fl_u.afs.link, &vnode->pending_locks);
397
398 /* If we've already got a lock on the server then try to move to having
399 * the VFS grant the requested lock. Note that this means that other
400 * clients may get starved out.
401 */
402 _debug("try %u", vnode->lock_state);
403 if (vnode->lock_state == AFS_VNODE_LOCK_GRANTED) {
404 if (type == AFS_LOCK_READ) {
405 _debug("instant readlock");
406 list_move_tail(&fl->fl_u.afs.link, &vnode->granted_locks);
407 fl->fl_u.afs.state = AFS_LOCK_GRANTED;
408 goto vnode_is_locked_u;
409 }
410
411 if (vnode->lock_type == AFS_LOCK_WRITE) {
412 _debug("instant writelock");
413 list_move_tail(&fl->fl_u.afs.link, &vnode->granted_locks);
414 fl->fl_u.afs.state = AFS_LOCK_GRANTED;
415 goto vnode_is_locked_u;
416 }
417 }
418
419 if (vnode->lock_state != AFS_VNODE_LOCK_NONE)
420 goto need_to_wait;
421
422 try_to_lock:
423 /* We don't have a lock on this vnode and we aren't currently waiting
424 * for one either, so ask the server for a lock.
425 *
426 * Note that we need to be careful if we get interrupted by a signal
427 * after dispatching the request as we may still get the lock, even
428 * though we don't wait for the reply (it's not too bad a problem - the
429 * lock will expire in 5 mins anyway).
430 */
431 _debug("not locked");
432 vnode->lock_key = key_get(key);
433 vnode->lock_type = type;
434 afs_set_lock_state(vnode, AFS_VNODE_LOCK_SETTING);
435 spin_unlock(&vnode->lock);
436
437 ret = afs_set_lock(vnode, key, type); /* RPC */
438
439 spin_lock(&vnode->lock);
440 switch (ret) {
441 case -EKEYREJECTED:
442 case -EKEYEXPIRED:
443 case -EKEYREVOKED:
444 case -EPERM:
445 case -EACCES:
446 fl->fl_u.afs.state = ret;
447 list_del_init(&fl->fl_u.afs.link);
448 afs_next_locker(vnode, ret);
449 goto error_unlock;
450
451 default:
452 fl->fl_u.afs.state = ret;
453 list_del_init(&fl->fl_u.afs.link);
454 afs_next_locker(vnode, 0);
455 goto error_unlock;
456
457 case -EWOULDBLOCK:
458 /* The server doesn't have a lock-waiting queue, so the client
459 * will have to retry. The server will break the outstanding
460 * callbacks on a file when a lock is released.
461 */
462 _debug("would block");
463 ASSERT(list_empty(&vnode->granted_locks));
464 ASSERTCMP(vnode->pending_locks.next, ==, &fl->fl_u.afs.link);
465 goto lock_is_contended;
466
467 case 0:
468 _debug("acquired");
469 afs_set_lock_state(vnode, AFS_VNODE_LOCK_GRANTED);
470 afs_grant_locks(vnode);
471 goto vnode_is_locked_u;
472 }
473
474 vnode_is_locked_u:
475 spin_unlock(&vnode->lock);
476 vnode_is_locked:
477 /* the lock has been granted by the server... */
478 ASSERTCMP(fl->fl_u.afs.state, ==, AFS_LOCK_GRANTED);
479
480 /* ... but the VFS still needs to distribute access on this client. */
481 ret = locks_lock_file_wait(file, fl);
482 if (ret < 0)
483 goto vfs_rejected_lock;
484
485 /* Again, make sure we've got a callback on this file and, again, make
486 * sure that our view of the data version is up to date (we ignore
487 * errors incurred here and deal with the consequences elsewhere).
488 */
489 afs_validate(vnode, key);
490 _leave(" = 0");
491 return 0;
492
493 lock_is_contended:
494 if (!(fl->fl_flags & FL_SLEEP)) {
495 list_del_init(&fl->fl_u.afs.link);
496 afs_next_locker(vnode, 0);
497 ret = -EAGAIN;
498 goto error_unlock;
499 }
500
501 afs_set_lock_state(vnode, AFS_VNODE_LOCK_WAITING_FOR_CB);
502 queue_delayed_work(afs_lock_manager, &vnode->lock_work, HZ * 5);
503
504 need_to_wait:
505 /* We're going to have to wait. Either this client doesn't have a lock
506 * on the server yet and we need to wait for a callback to occur, or
507 * the client does have a lock on the server, but it's shared and we
508 * need an exclusive lock.
509 */
510 spin_unlock(&vnode->lock);
511
512 _debug("sleep");
513 ret = wait_event_interruptible(fl->fl_wait,
514 fl->fl_u.afs.state != AFS_LOCK_PENDING);
515 _debug("wait = %d", ret);
516
517 if (fl->fl_u.afs.state >= 0 && fl->fl_u.afs.state != AFS_LOCK_GRANTED) {
518 spin_lock(&vnode->lock);
519
520 switch (fl->fl_u.afs.state) {
521 case AFS_LOCK_YOUR_TRY:
522 fl->fl_u.afs.state = AFS_LOCK_PENDING;
523 goto try_to_lock;
524 case AFS_LOCK_PENDING:
525 if (ret > 0) {
526 /* We need to retry the lock. We may not be
527 * notified by the server if it just expired
528 * rather than being released.
529 */
530 ASSERTCMP(vnode->lock_state, ==, AFS_VNODE_LOCK_WAITING_FOR_CB);
531 afs_set_lock_state(vnode, AFS_VNODE_LOCK_SETTING);
532 fl->fl_u.afs.state = AFS_LOCK_PENDING;
533 goto try_to_lock;
534 }
535 goto error_unlock;
536 case AFS_LOCK_GRANTED:
537 default:
538 break;
539 }
540
541 spin_unlock(&vnode->lock);
542 }
543
544 if (fl->fl_u.afs.state == AFS_LOCK_GRANTED)
545 goto vnode_is_locked;
546 ret = fl->fl_u.afs.state;
547 goto error;
548
549 vfs_rejected_lock:
550 /* The VFS rejected the lock we just obtained, so we have to discard
551 * what we just got. We defer this to the lock manager work item to
552 * deal with.
553 */
554 _debug("vfs refused %d", ret);
555 spin_lock(&vnode->lock);
556 list_del_init(&fl->fl_u.afs.link);
557 afs_defer_unlock(vnode);
558
559 error_unlock:
560 spin_unlock(&vnode->lock);
561 error:
562 _leave(" = %d", ret);
563 return ret;
564 }
565
566 /*
567 * unlock on a file on the server
568 */
afs_do_unlk(struct file * file,struct file_lock * fl)569 static int afs_do_unlk(struct file *file, struct file_lock *fl)
570 {
571 struct afs_vnode *vnode = AFS_FS_I(locks_inode(file));
572 int ret;
573
574 _enter("{%x:%u},%u", vnode->fid.vid, vnode->fid.vnode, fl->fl_type);
575
576 /* Flush all pending writes before doing anything with locks. */
577 vfs_fsync(file, 0);
578
579 ret = locks_lock_file_wait(file, fl);
580 _leave(" = %d [%u]", ret, vnode->lock_state);
581 return ret;
582 }
583
584 /*
585 * return information about a lock we currently hold, if indeed we hold one
586 */
afs_do_getlk(struct file * file,struct file_lock * fl)587 static int afs_do_getlk(struct file *file, struct file_lock *fl)
588 {
589 struct afs_vnode *vnode = AFS_FS_I(locks_inode(file));
590 struct key *key = afs_file_key(file);
591 int ret, lock_count;
592
593 _enter("");
594
595 fl->fl_type = F_UNLCK;
596
597 /* check local lock records first */
598 posix_test_lock(file, fl);
599 if (fl->fl_type == F_UNLCK) {
600 /* no local locks; consult the server */
601 ret = afs_fetch_status(vnode, key, false);
602 if (ret < 0)
603 goto error;
604
605 lock_count = READ_ONCE(vnode->status.lock_count);
606 if (lock_count != 0) {
607 if (lock_count > 0)
608 fl->fl_type = F_RDLCK;
609 else
610 fl->fl_type = F_WRLCK;
611 fl->fl_start = 0;
612 fl->fl_end = OFFSET_MAX;
613 fl->fl_pid = 0;
614 }
615 }
616
617 ret = 0;
618 error:
619 _leave(" = %d [%hd]", ret, fl->fl_type);
620 return ret;
621 }
622
623 /*
624 * manage POSIX locks on a file
625 */
afs_lock(struct file * file,int cmd,struct file_lock * fl)626 int afs_lock(struct file *file, int cmd, struct file_lock *fl)
627 {
628 struct afs_vnode *vnode = AFS_FS_I(locks_inode(file));
629
630 _enter("{%x:%u},%d,{t=%x,fl=%x,r=%Ld:%Ld}",
631 vnode->fid.vid, vnode->fid.vnode, cmd,
632 fl->fl_type, fl->fl_flags,
633 (long long) fl->fl_start, (long long) fl->fl_end);
634
635 /* AFS doesn't support mandatory locks */
636 if (__mandatory_lock(&vnode->vfs_inode) && fl->fl_type != F_UNLCK)
637 return -ENOLCK;
638
639 if (IS_GETLK(cmd))
640 return afs_do_getlk(file, fl);
641 if (fl->fl_type == F_UNLCK)
642 return afs_do_unlk(file, fl);
643 return afs_do_setlk(file, fl);
644 }
645
646 /*
647 * manage FLOCK locks on a file
648 */
afs_flock(struct file * file,int cmd,struct file_lock * fl)649 int afs_flock(struct file *file, int cmd, struct file_lock *fl)
650 {
651 struct afs_vnode *vnode = AFS_FS_I(locks_inode(file));
652
653 _enter("{%x:%u},%d,{t=%x,fl=%x}",
654 vnode->fid.vid, vnode->fid.vnode, cmd,
655 fl->fl_type, fl->fl_flags);
656
657 /*
658 * No BSD flocks over NFS allowed.
659 * Note: we could try to fake a POSIX lock request here by
660 * using ((u32) filp | 0x80000000) or some such as the pid.
661 * Not sure whether that would be unique, though, or whether
662 * that would break in other places.
663 */
664 if (!(fl->fl_flags & FL_FLOCK))
665 return -ENOLCK;
666
667 /* we're simulating flock() locks using posix locks on the server */
668 if (fl->fl_type == F_UNLCK)
669 return afs_do_unlk(file, fl);
670 return afs_do_setlk(file, fl);
671 }
672
673 /*
674 * the POSIX lock management core VFS code copies the lock record and adds the
675 * copy into its own list, so we need to add that copy to the vnode's lock
676 * queue in the same place as the original (which will be deleted shortly
677 * after)
678 */
afs_fl_copy_lock(struct file_lock * new,struct file_lock * fl)679 static void afs_fl_copy_lock(struct file_lock *new, struct file_lock *fl)
680 {
681 struct afs_vnode *vnode = AFS_FS_I(locks_inode(fl->fl_file));
682
683 _enter("");
684
685 spin_lock(&vnode->lock);
686 list_add(&new->fl_u.afs.link, &fl->fl_u.afs.link);
687 spin_unlock(&vnode->lock);
688 }
689
690 /*
691 * need to remove this lock from the vnode queue when it's removed from the
692 * VFS's list
693 */
afs_fl_release_private(struct file_lock * fl)694 static void afs_fl_release_private(struct file_lock *fl)
695 {
696 struct afs_vnode *vnode = AFS_FS_I(locks_inode(fl->fl_file));
697
698 _enter("");
699
700 spin_lock(&vnode->lock);
701
702 list_del_init(&fl->fl_u.afs.link);
703 if (list_empty(&vnode->granted_locks))
704 afs_defer_unlock(vnode);
705
706 _debug("state %u for %p", vnode->lock_state, vnode);
707 spin_unlock(&vnode->lock);
708 }
709