1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* AFS file locking support
3 *
4 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells (dhowells@redhat.com)
6 */
7
8 #include "internal.h"
9
10 #define AFS_LOCK_GRANTED 0
11 #define AFS_LOCK_PENDING 1
12 #define AFS_LOCK_YOUR_TRY 2
13
14 struct workqueue_struct *afs_lock_manager;
15
16 static void afs_next_locker(struct afs_vnode *vnode, int error);
17 static void afs_fl_copy_lock(struct file_lock *new, struct file_lock *fl);
18 static void afs_fl_release_private(struct file_lock *fl);
19
20 static const struct file_lock_operations afs_lock_ops = {
21 .fl_copy_lock = afs_fl_copy_lock,
22 .fl_release_private = afs_fl_release_private,
23 };
24
afs_set_lock_state(struct afs_vnode * vnode,enum afs_lock_state state)25 static inline void afs_set_lock_state(struct afs_vnode *vnode, enum afs_lock_state state)
26 {
27 _debug("STATE %u -> %u", vnode->lock_state, state);
28 vnode->lock_state = state;
29 }
30
31 static atomic_t afs_file_lock_debug_id;
32
33 /*
34 * if the callback is broken on this vnode, then the lock may now be available
35 */
afs_lock_may_be_available(struct afs_vnode * vnode)36 void afs_lock_may_be_available(struct afs_vnode *vnode)
37 {
38 _enter("{%llx:%llu}", vnode->fid.vid, vnode->fid.vnode);
39
40 spin_lock(&vnode->lock);
41 if (vnode->lock_state == AFS_VNODE_LOCK_WAITING_FOR_CB)
42 afs_next_locker(vnode, 0);
43 trace_afs_flock_ev(vnode, NULL, afs_flock_callback_break, 0);
44 spin_unlock(&vnode->lock);
45 }
46
47 /*
48 * the lock will time out in 5 minutes unless we extend it, so schedule
49 * extension in a bit less than that time
50 */
afs_schedule_lock_extension(struct afs_vnode * vnode)51 static void afs_schedule_lock_extension(struct afs_vnode *vnode)
52 {
53 ktime_t expires_at, now, duration;
54 u64 duration_j;
55
56 expires_at = ktime_add_ms(vnode->locked_at, AFS_LOCKWAIT * 1000 / 2);
57 now = ktime_get_real();
58 duration = ktime_sub(expires_at, now);
59 if (duration <= 0)
60 duration_j = 0;
61 else
62 duration_j = nsecs_to_jiffies(ktime_to_ns(duration));
63
64 queue_delayed_work(afs_lock_manager, &vnode->lock_work, duration_j);
65 }
66
67 /*
68 * In the case of successful completion of a lock operation, record the time
69 * the reply appeared and start the lock extension timer.
70 */
afs_lock_op_done(struct afs_call * call)71 void afs_lock_op_done(struct afs_call *call)
72 {
73 struct afs_operation *op = call->op;
74 struct afs_vnode *vnode = op->file[0].vnode;
75
76 if (call->error == 0) {
77 spin_lock(&vnode->lock);
78 trace_afs_flock_ev(vnode, NULL, afs_flock_timestamp, 0);
79 vnode->locked_at = call->reply_time;
80 afs_schedule_lock_extension(vnode);
81 spin_unlock(&vnode->lock);
82 }
83 }
84
85 /*
86 * grant one or more locks (readlocks are allowed to jump the queue if the
87 * first lock in the queue is itself a readlock)
88 * - the caller must hold the vnode lock
89 */
afs_grant_locks(struct afs_vnode * vnode)90 static void afs_grant_locks(struct afs_vnode *vnode)
91 {
92 struct file_lock *p, *_p;
93 bool exclusive = (vnode->lock_type == AFS_LOCK_WRITE);
94
95 list_for_each_entry_safe(p, _p, &vnode->pending_locks, fl_u.afs.link) {
96 if (!exclusive && p->fl_type == F_WRLCK)
97 continue;
98
99 list_move_tail(&p->fl_u.afs.link, &vnode->granted_locks);
100 p->fl_u.afs.state = AFS_LOCK_GRANTED;
101 trace_afs_flock_op(vnode, p, afs_flock_op_grant);
102 wake_up(&p->fl_wait);
103 }
104 }
105
106 /*
107 * If an error is specified, reject every pending lock that matches the
108 * authentication and type of the lock we failed to get. If there are any
109 * remaining lockers, try to wake up one of them to have a go.
110 */
afs_next_locker(struct afs_vnode * vnode,int error)111 static void afs_next_locker(struct afs_vnode *vnode, int error)
112 {
113 struct file_lock *p, *_p, *next = NULL;
114 struct key *key = vnode->lock_key;
115 unsigned int fl_type = F_RDLCK;
116
117 _enter("");
118
119 if (vnode->lock_type == AFS_LOCK_WRITE)
120 fl_type = F_WRLCK;
121
122 list_for_each_entry_safe(p, _p, &vnode->pending_locks, fl_u.afs.link) {
123 if (error &&
124 p->fl_type == fl_type &&
125 afs_file_key(p->fl_file) == key) {
126 list_del_init(&p->fl_u.afs.link);
127 p->fl_u.afs.state = error;
128 wake_up(&p->fl_wait);
129 }
130
131 /* Select the next locker to hand off to. */
132 if (next &&
133 (next->fl_type == F_WRLCK || p->fl_type == F_RDLCK))
134 continue;
135 next = p;
136 }
137
138 vnode->lock_key = NULL;
139 key_put(key);
140
141 if (next) {
142 afs_set_lock_state(vnode, AFS_VNODE_LOCK_SETTING);
143 next->fl_u.afs.state = AFS_LOCK_YOUR_TRY;
144 trace_afs_flock_op(vnode, next, afs_flock_op_wake);
145 wake_up(&next->fl_wait);
146 } else {
147 afs_set_lock_state(vnode, AFS_VNODE_LOCK_NONE);
148 trace_afs_flock_ev(vnode, NULL, afs_flock_no_lockers, 0);
149 }
150
151 _leave("");
152 }
153
154 /*
155 * Kill off all waiters in the the pending lock queue due to the vnode being
156 * deleted.
157 */
afs_kill_lockers_enoent(struct afs_vnode * vnode)158 static void afs_kill_lockers_enoent(struct afs_vnode *vnode)
159 {
160 struct file_lock *p;
161
162 afs_set_lock_state(vnode, AFS_VNODE_LOCK_DELETED);
163
164 while (!list_empty(&vnode->pending_locks)) {
165 p = list_entry(vnode->pending_locks.next,
166 struct file_lock, fl_u.afs.link);
167 list_del_init(&p->fl_u.afs.link);
168 p->fl_u.afs.state = -ENOENT;
169 wake_up(&p->fl_wait);
170 }
171
172 key_put(vnode->lock_key);
173 vnode->lock_key = NULL;
174 }
175
afs_lock_success(struct afs_operation * op)176 static void afs_lock_success(struct afs_operation *op)
177 {
178 _enter("op=%08x", op->debug_id);
179 afs_vnode_commit_status(op, &op->file[0]);
180 }
181
182 static const struct afs_operation_ops afs_set_lock_operation = {
183 .issue_afs_rpc = afs_fs_set_lock,
184 .issue_yfs_rpc = yfs_fs_set_lock,
185 .success = afs_lock_success,
186 .aborted = afs_check_for_remote_deletion,
187 };
188
189 /*
190 * Get a lock on a file
191 */
afs_set_lock(struct afs_vnode * vnode,struct key * key,afs_lock_type_t type)192 static int afs_set_lock(struct afs_vnode *vnode, struct key *key,
193 afs_lock_type_t type)
194 {
195 struct afs_operation *op;
196
197 _enter("%s{%llx:%llu.%u},%x,%u",
198 vnode->volume->name,
199 vnode->fid.vid,
200 vnode->fid.vnode,
201 vnode->fid.unique,
202 key_serial(key), type);
203
204 op = afs_alloc_operation(key, vnode->volume);
205 if (IS_ERR(op))
206 return PTR_ERR(op);
207
208 afs_op_set_vnode(op, 0, vnode);
209
210 op->lock.type = type;
211 op->ops = &afs_set_lock_operation;
212 return afs_do_sync_operation(op);
213 }
214
215 static const struct afs_operation_ops afs_extend_lock_operation = {
216 .issue_afs_rpc = afs_fs_extend_lock,
217 .issue_yfs_rpc = yfs_fs_extend_lock,
218 .success = afs_lock_success,
219 };
220
221 /*
222 * Extend a lock on a file
223 */
afs_extend_lock(struct afs_vnode * vnode,struct key * key)224 static int afs_extend_lock(struct afs_vnode *vnode, struct key *key)
225 {
226 struct afs_operation *op;
227
228 _enter("%s{%llx:%llu.%u},%x",
229 vnode->volume->name,
230 vnode->fid.vid,
231 vnode->fid.vnode,
232 vnode->fid.unique,
233 key_serial(key));
234
235 op = afs_alloc_operation(key, vnode->volume);
236 if (IS_ERR(op))
237 return PTR_ERR(op);
238
239 afs_op_set_vnode(op, 0, vnode);
240
241 op->flags |= AFS_OPERATION_UNINTR;
242 op->ops = &afs_extend_lock_operation;
243 return afs_do_sync_operation(op);
244 }
245
246 static const struct afs_operation_ops afs_release_lock_operation = {
247 .issue_afs_rpc = afs_fs_release_lock,
248 .issue_yfs_rpc = yfs_fs_release_lock,
249 .success = afs_lock_success,
250 };
251
252 /*
253 * Release a lock on a file
254 */
afs_release_lock(struct afs_vnode * vnode,struct key * key)255 static int afs_release_lock(struct afs_vnode *vnode, struct key *key)
256 {
257 struct afs_operation *op;
258
259 _enter("%s{%llx:%llu.%u},%x",
260 vnode->volume->name,
261 vnode->fid.vid,
262 vnode->fid.vnode,
263 vnode->fid.unique,
264 key_serial(key));
265
266 op = afs_alloc_operation(key, vnode->volume);
267 if (IS_ERR(op))
268 return PTR_ERR(op);
269
270 afs_op_set_vnode(op, 0, vnode);
271
272 op->flags |= AFS_OPERATION_UNINTR;
273 op->ops = &afs_release_lock_operation;
274 return afs_do_sync_operation(op);
275 }
276
277 /*
278 * do work for a lock, including:
279 * - probing for a lock we're waiting on but didn't get immediately
280 * - extending a lock that's close to timing out
281 */
afs_lock_work(struct work_struct * work)282 void afs_lock_work(struct work_struct *work)
283 {
284 struct afs_vnode *vnode =
285 container_of(work, struct afs_vnode, lock_work.work);
286 struct key *key;
287 int ret;
288
289 _enter("{%llx:%llu}", vnode->fid.vid, vnode->fid.vnode);
290
291 spin_lock(&vnode->lock);
292
293 again:
294 _debug("wstate %u for %p", vnode->lock_state, vnode);
295 switch (vnode->lock_state) {
296 case AFS_VNODE_LOCK_NEED_UNLOCK:
297 afs_set_lock_state(vnode, AFS_VNODE_LOCK_UNLOCKING);
298 trace_afs_flock_ev(vnode, NULL, afs_flock_work_unlocking, 0);
299 spin_unlock(&vnode->lock);
300
301 /* attempt to release the server lock; if it fails, we just
302 * wait 5 minutes and it'll expire anyway */
303 ret = afs_release_lock(vnode, vnode->lock_key);
304 if (ret < 0 && vnode->lock_state != AFS_VNODE_LOCK_DELETED) {
305 trace_afs_flock_ev(vnode, NULL, afs_flock_release_fail,
306 ret);
307 printk(KERN_WARNING "AFS:"
308 " Failed to release lock on {%llx:%llx} error %d\n",
309 vnode->fid.vid, vnode->fid.vnode, ret);
310 }
311
312 spin_lock(&vnode->lock);
313 if (ret == -ENOENT)
314 afs_kill_lockers_enoent(vnode);
315 else
316 afs_next_locker(vnode, 0);
317 spin_unlock(&vnode->lock);
318 return;
319
320 /* If we've already got a lock, then it must be time to extend that
321 * lock as AFS locks time out after 5 minutes.
322 */
323 case AFS_VNODE_LOCK_GRANTED:
324 _debug("extend");
325
326 ASSERT(!list_empty(&vnode->granted_locks));
327
328 key = key_get(vnode->lock_key);
329 afs_set_lock_state(vnode, AFS_VNODE_LOCK_EXTENDING);
330 trace_afs_flock_ev(vnode, NULL, afs_flock_work_extending, 0);
331 spin_unlock(&vnode->lock);
332
333 ret = afs_extend_lock(vnode, key); /* RPC */
334 key_put(key);
335
336 if (ret < 0) {
337 trace_afs_flock_ev(vnode, NULL, afs_flock_extend_fail,
338 ret);
339 pr_warn("AFS: Failed to extend lock on {%llx:%llx} error %d\n",
340 vnode->fid.vid, vnode->fid.vnode, ret);
341 }
342
343 spin_lock(&vnode->lock);
344
345 if (ret == -ENOENT) {
346 afs_kill_lockers_enoent(vnode);
347 spin_unlock(&vnode->lock);
348 return;
349 }
350
351 if (vnode->lock_state != AFS_VNODE_LOCK_EXTENDING)
352 goto again;
353 afs_set_lock_state(vnode, AFS_VNODE_LOCK_GRANTED);
354
355 if (ret != 0)
356 queue_delayed_work(afs_lock_manager, &vnode->lock_work,
357 HZ * 10);
358 spin_unlock(&vnode->lock);
359 _leave(" [ext]");
360 return;
361
362 /* If we're waiting for a callback to indicate lock release, we can't
363 * actually rely on this, so need to recheck at regular intervals. The
364 * problem is that the server might not notify us if the lock just
365 * expires (say because a client died) rather than being explicitly
366 * released.
367 */
368 case AFS_VNODE_LOCK_WAITING_FOR_CB:
369 _debug("retry");
370 afs_next_locker(vnode, 0);
371 spin_unlock(&vnode->lock);
372 return;
373
374 case AFS_VNODE_LOCK_DELETED:
375 afs_kill_lockers_enoent(vnode);
376 spin_unlock(&vnode->lock);
377 return;
378
379 default:
380 /* Looks like a lock request was withdrawn. */
381 spin_unlock(&vnode->lock);
382 _leave(" [no]");
383 return;
384 }
385 }
386
387 /*
388 * pass responsibility for the unlocking of a vnode on the server to the
389 * manager thread, lest a pending signal in the calling thread interrupt
390 * AF_RXRPC
391 * - the caller must hold the vnode lock
392 */
afs_defer_unlock(struct afs_vnode * vnode)393 static void afs_defer_unlock(struct afs_vnode *vnode)
394 {
395 _enter("%u", vnode->lock_state);
396
397 if (list_empty(&vnode->granted_locks) &&
398 (vnode->lock_state == AFS_VNODE_LOCK_GRANTED ||
399 vnode->lock_state == AFS_VNODE_LOCK_EXTENDING)) {
400 cancel_delayed_work(&vnode->lock_work);
401
402 afs_set_lock_state(vnode, AFS_VNODE_LOCK_NEED_UNLOCK);
403 trace_afs_flock_ev(vnode, NULL, afs_flock_defer_unlock, 0);
404 queue_delayed_work(afs_lock_manager, &vnode->lock_work, 0);
405 }
406 }
407
408 /*
409 * Check that our view of the file metadata is up to date and check to see
410 * whether we think that we have a locking permit.
411 */
afs_do_setlk_check(struct afs_vnode * vnode,struct key * key,enum afs_flock_mode mode,afs_lock_type_t type)412 static int afs_do_setlk_check(struct afs_vnode *vnode, struct key *key,
413 enum afs_flock_mode mode, afs_lock_type_t type)
414 {
415 afs_access_t access;
416 int ret;
417
418 /* Make sure we've got a callback on this file and that our view of the
419 * data version is up to date.
420 */
421 ret = afs_validate(vnode, key);
422 if (ret < 0)
423 return ret;
424
425 /* Check the permission set to see if we're actually going to be
426 * allowed to get a lock on this file.
427 */
428 ret = afs_check_permit(vnode, key, &access);
429 if (ret < 0)
430 return ret;
431
432 /* At a rough estimation, you need LOCK, WRITE or INSERT perm to
433 * read-lock a file and WRITE or INSERT perm to write-lock a file.
434 *
435 * We can't rely on the server to do this for us since if we want to
436 * share a read lock that we already have, we won't go the server.
437 */
438 if (type == AFS_LOCK_READ) {
439 if (!(access & (AFS_ACE_INSERT | AFS_ACE_WRITE | AFS_ACE_LOCK)))
440 return -EACCES;
441 } else {
442 if (!(access & (AFS_ACE_INSERT | AFS_ACE_WRITE)))
443 return -EACCES;
444 }
445
446 return 0;
447 }
448
449 /*
450 * request a lock on a file on the server
451 */
afs_do_setlk(struct file * file,struct file_lock * fl)452 static int afs_do_setlk(struct file *file, struct file_lock *fl)
453 {
454 struct inode *inode = locks_inode(file);
455 struct afs_vnode *vnode = AFS_FS_I(inode);
456 enum afs_flock_mode mode = AFS_FS_S(inode->i_sb)->flock_mode;
457 afs_lock_type_t type;
458 struct key *key = afs_file_key(file);
459 bool partial, no_server_lock = false;
460 int ret;
461
462 if (mode == afs_flock_mode_unset)
463 mode = afs_flock_mode_openafs;
464
465 _enter("{%llx:%llu},%llu-%llu,%u,%u",
466 vnode->fid.vid, vnode->fid.vnode,
467 fl->fl_start, fl->fl_end, fl->fl_type, mode);
468
469 fl->fl_ops = &afs_lock_ops;
470 INIT_LIST_HEAD(&fl->fl_u.afs.link);
471 fl->fl_u.afs.state = AFS_LOCK_PENDING;
472
473 partial = (fl->fl_start != 0 || fl->fl_end != OFFSET_MAX);
474 type = (fl->fl_type == F_RDLCK) ? AFS_LOCK_READ : AFS_LOCK_WRITE;
475 if (mode == afs_flock_mode_write && partial)
476 type = AFS_LOCK_WRITE;
477
478 ret = afs_do_setlk_check(vnode, key, mode, type);
479 if (ret < 0)
480 return ret;
481
482 trace_afs_flock_op(vnode, fl, afs_flock_op_set_lock);
483
484 /* AFS3 protocol only supports full-file locks and doesn't provide any
485 * method of upgrade/downgrade, so we need to emulate for partial-file
486 * locks.
487 *
488 * The OpenAFS client only gets a server lock for a full-file lock and
489 * keeps partial-file locks local. Allow this behaviour to be emulated
490 * (as the default).
491 */
492 if (mode == afs_flock_mode_local ||
493 (partial && mode == afs_flock_mode_openafs)) {
494 no_server_lock = true;
495 goto skip_server_lock;
496 }
497
498 spin_lock(&vnode->lock);
499 list_add_tail(&fl->fl_u.afs.link, &vnode->pending_locks);
500
501 ret = -ENOENT;
502 if (vnode->lock_state == AFS_VNODE_LOCK_DELETED)
503 goto error_unlock;
504
505 /* If we've already got a lock on the server then try to move to having
506 * the VFS grant the requested lock. Note that this means that other
507 * clients may get starved out.
508 */
509 _debug("try %u", vnode->lock_state);
510 if (vnode->lock_state == AFS_VNODE_LOCK_GRANTED) {
511 if (type == AFS_LOCK_READ) {
512 _debug("instant readlock");
513 list_move_tail(&fl->fl_u.afs.link, &vnode->granted_locks);
514 fl->fl_u.afs.state = AFS_LOCK_GRANTED;
515 goto vnode_is_locked_u;
516 }
517
518 if (vnode->lock_type == AFS_LOCK_WRITE) {
519 _debug("instant writelock");
520 list_move_tail(&fl->fl_u.afs.link, &vnode->granted_locks);
521 fl->fl_u.afs.state = AFS_LOCK_GRANTED;
522 goto vnode_is_locked_u;
523 }
524 }
525
526 if (vnode->lock_state == AFS_VNODE_LOCK_NONE &&
527 !(fl->fl_flags & FL_SLEEP)) {
528 ret = -EAGAIN;
529 if (type == AFS_LOCK_READ) {
530 if (vnode->status.lock_count == -1)
531 goto lock_is_contended; /* Write locked */
532 } else {
533 if (vnode->status.lock_count != 0)
534 goto lock_is_contended; /* Locked */
535 }
536 }
537
538 if (vnode->lock_state != AFS_VNODE_LOCK_NONE)
539 goto need_to_wait;
540
541 try_to_lock:
542 /* We don't have a lock on this vnode and we aren't currently waiting
543 * for one either, so ask the server for a lock.
544 *
545 * Note that we need to be careful if we get interrupted by a signal
546 * after dispatching the request as we may still get the lock, even
547 * though we don't wait for the reply (it's not too bad a problem - the
548 * lock will expire in 5 mins anyway).
549 */
550 trace_afs_flock_ev(vnode, fl, afs_flock_try_to_lock, 0);
551 vnode->lock_key = key_get(key);
552 vnode->lock_type = type;
553 afs_set_lock_state(vnode, AFS_VNODE_LOCK_SETTING);
554 spin_unlock(&vnode->lock);
555
556 ret = afs_set_lock(vnode, key, type); /* RPC */
557
558 spin_lock(&vnode->lock);
559 switch (ret) {
560 case -EKEYREJECTED:
561 case -EKEYEXPIRED:
562 case -EKEYREVOKED:
563 case -EPERM:
564 case -EACCES:
565 fl->fl_u.afs.state = ret;
566 trace_afs_flock_ev(vnode, fl, afs_flock_fail_perm, ret);
567 list_del_init(&fl->fl_u.afs.link);
568 afs_next_locker(vnode, ret);
569 goto error_unlock;
570
571 case -ENOENT:
572 fl->fl_u.afs.state = ret;
573 trace_afs_flock_ev(vnode, fl, afs_flock_fail_other, ret);
574 list_del_init(&fl->fl_u.afs.link);
575 afs_kill_lockers_enoent(vnode);
576 goto error_unlock;
577
578 default:
579 fl->fl_u.afs.state = ret;
580 trace_afs_flock_ev(vnode, fl, afs_flock_fail_other, ret);
581 list_del_init(&fl->fl_u.afs.link);
582 afs_next_locker(vnode, 0);
583 goto error_unlock;
584
585 case -EWOULDBLOCK:
586 /* The server doesn't have a lock-waiting queue, so the client
587 * will have to retry. The server will break the outstanding
588 * callbacks on a file when a lock is released.
589 */
590 ASSERT(list_empty(&vnode->granted_locks));
591 ASSERTCMP(vnode->pending_locks.next, ==, &fl->fl_u.afs.link);
592 goto lock_is_contended;
593
594 case 0:
595 afs_set_lock_state(vnode, AFS_VNODE_LOCK_GRANTED);
596 trace_afs_flock_ev(vnode, fl, afs_flock_acquired, type);
597 afs_grant_locks(vnode);
598 goto vnode_is_locked_u;
599 }
600
601 vnode_is_locked_u:
602 spin_unlock(&vnode->lock);
603 vnode_is_locked:
604 /* the lock has been granted by the server... */
605 ASSERTCMP(fl->fl_u.afs.state, ==, AFS_LOCK_GRANTED);
606
607 skip_server_lock:
608 /* ... but the VFS still needs to distribute access on this client. */
609 trace_afs_flock_ev(vnode, fl, afs_flock_vfs_locking, 0);
610 ret = locks_lock_file_wait(file, fl);
611 trace_afs_flock_ev(vnode, fl, afs_flock_vfs_lock, ret);
612 if (ret < 0)
613 goto vfs_rejected_lock;
614
615 /* Again, make sure we've got a callback on this file and, again, make
616 * sure that our view of the data version is up to date (we ignore
617 * errors incurred here and deal with the consequences elsewhere).
618 */
619 afs_validate(vnode, key);
620 _leave(" = 0");
621 return 0;
622
623 lock_is_contended:
624 if (!(fl->fl_flags & FL_SLEEP)) {
625 list_del_init(&fl->fl_u.afs.link);
626 afs_next_locker(vnode, 0);
627 ret = -EAGAIN;
628 goto error_unlock;
629 }
630
631 afs_set_lock_state(vnode, AFS_VNODE_LOCK_WAITING_FOR_CB);
632 trace_afs_flock_ev(vnode, fl, afs_flock_would_block, ret);
633 queue_delayed_work(afs_lock_manager, &vnode->lock_work, HZ * 5);
634
635 need_to_wait:
636 /* We're going to have to wait. Either this client doesn't have a lock
637 * on the server yet and we need to wait for a callback to occur, or
638 * the client does have a lock on the server, but it's shared and we
639 * need an exclusive lock.
640 */
641 spin_unlock(&vnode->lock);
642
643 trace_afs_flock_ev(vnode, fl, afs_flock_waiting, 0);
644 ret = wait_event_interruptible(fl->fl_wait,
645 fl->fl_u.afs.state != AFS_LOCK_PENDING);
646 trace_afs_flock_ev(vnode, fl, afs_flock_waited, ret);
647
648 if (fl->fl_u.afs.state >= 0 && fl->fl_u.afs.state != AFS_LOCK_GRANTED) {
649 spin_lock(&vnode->lock);
650
651 switch (fl->fl_u.afs.state) {
652 case AFS_LOCK_YOUR_TRY:
653 fl->fl_u.afs.state = AFS_LOCK_PENDING;
654 goto try_to_lock;
655 case AFS_LOCK_PENDING:
656 if (ret > 0) {
657 /* We need to retry the lock. We may not be
658 * notified by the server if it just expired
659 * rather than being released.
660 */
661 ASSERTCMP(vnode->lock_state, ==, AFS_VNODE_LOCK_WAITING_FOR_CB);
662 afs_set_lock_state(vnode, AFS_VNODE_LOCK_SETTING);
663 fl->fl_u.afs.state = AFS_LOCK_PENDING;
664 goto try_to_lock;
665 }
666 goto error_unlock;
667 case AFS_LOCK_GRANTED:
668 default:
669 break;
670 }
671
672 spin_unlock(&vnode->lock);
673 }
674
675 if (fl->fl_u.afs.state == AFS_LOCK_GRANTED)
676 goto vnode_is_locked;
677 ret = fl->fl_u.afs.state;
678 goto error;
679
680 vfs_rejected_lock:
681 /* The VFS rejected the lock we just obtained, so we have to discard
682 * what we just got. We defer this to the lock manager work item to
683 * deal with.
684 */
685 _debug("vfs refused %d", ret);
686 if (no_server_lock)
687 goto error;
688 spin_lock(&vnode->lock);
689 list_del_init(&fl->fl_u.afs.link);
690 afs_defer_unlock(vnode);
691
692 error_unlock:
693 spin_unlock(&vnode->lock);
694 error:
695 _leave(" = %d", ret);
696 return ret;
697 }
698
699 /*
700 * unlock on a file on the server
701 */
afs_do_unlk(struct file * file,struct file_lock * fl)702 static int afs_do_unlk(struct file *file, struct file_lock *fl)
703 {
704 struct afs_vnode *vnode = AFS_FS_I(locks_inode(file));
705 int ret;
706
707 _enter("{%llx:%llu},%u", vnode->fid.vid, vnode->fid.vnode, fl->fl_type);
708
709 trace_afs_flock_op(vnode, fl, afs_flock_op_unlock);
710
711 /* Flush all pending writes before doing anything with locks. */
712 vfs_fsync(file, 0);
713
714 ret = locks_lock_file_wait(file, fl);
715 _leave(" = %d [%u]", ret, vnode->lock_state);
716 return ret;
717 }
718
719 /*
720 * return information about a lock we currently hold, if indeed we hold one
721 */
afs_do_getlk(struct file * file,struct file_lock * fl)722 static int afs_do_getlk(struct file *file, struct file_lock *fl)
723 {
724 struct afs_vnode *vnode = AFS_FS_I(locks_inode(file));
725 struct key *key = afs_file_key(file);
726 int ret, lock_count;
727
728 _enter("");
729
730 if (vnode->lock_state == AFS_VNODE_LOCK_DELETED)
731 return -ENOENT;
732
733 fl->fl_type = F_UNLCK;
734
735 /* check local lock records first */
736 posix_test_lock(file, fl);
737 if (fl->fl_type == F_UNLCK) {
738 /* no local locks; consult the server */
739 ret = afs_fetch_status(vnode, key, false, NULL);
740 if (ret < 0)
741 goto error;
742
743 lock_count = READ_ONCE(vnode->status.lock_count);
744 if (lock_count != 0) {
745 if (lock_count > 0)
746 fl->fl_type = F_RDLCK;
747 else
748 fl->fl_type = F_WRLCK;
749 fl->fl_start = 0;
750 fl->fl_end = OFFSET_MAX;
751 fl->fl_pid = 0;
752 }
753 }
754
755 ret = 0;
756 error:
757 _leave(" = %d [%hd]", ret, fl->fl_type);
758 return ret;
759 }
760
761 /*
762 * manage POSIX locks on a file
763 */
afs_lock(struct file * file,int cmd,struct file_lock * fl)764 int afs_lock(struct file *file, int cmd, struct file_lock *fl)
765 {
766 struct afs_vnode *vnode = AFS_FS_I(locks_inode(file));
767 enum afs_flock_operation op;
768 int ret;
769
770 _enter("{%llx:%llu},%d,{t=%x,fl=%x,r=%Ld:%Ld}",
771 vnode->fid.vid, vnode->fid.vnode, cmd,
772 fl->fl_type, fl->fl_flags,
773 (long long) fl->fl_start, (long long) fl->fl_end);
774
775 /* AFS doesn't support mandatory locks */
776 if (__mandatory_lock(&vnode->vfs_inode) && fl->fl_type != F_UNLCK)
777 return -ENOLCK;
778
779 if (IS_GETLK(cmd))
780 return afs_do_getlk(file, fl);
781
782 fl->fl_u.afs.debug_id = atomic_inc_return(&afs_file_lock_debug_id);
783 trace_afs_flock_op(vnode, fl, afs_flock_op_lock);
784
785 if (fl->fl_type == F_UNLCK)
786 ret = afs_do_unlk(file, fl);
787 else
788 ret = afs_do_setlk(file, fl);
789
790 switch (ret) {
791 case 0: op = afs_flock_op_return_ok; break;
792 case -EAGAIN: op = afs_flock_op_return_eagain; break;
793 case -EDEADLK: op = afs_flock_op_return_edeadlk; break;
794 default: op = afs_flock_op_return_error; break;
795 }
796 trace_afs_flock_op(vnode, fl, op);
797 return ret;
798 }
799
800 /*
801 * manage FLOCK locks on a file
802 */
afs_flock(struct file * file,int cmd,struct file_lock * fl)803 int afs_flock(struct file *file, int cmd, struct file_lock *fl)
804 {
805 struct afs_vnode *vnode = AFS_FS_I(locks_inode(file));
806 enum afs_flock_operation op;
807 int ret;
808
809 _enter("{%llx:%llu},%d,{t=%x,fl=%x}",
810 vnode->fid.vid, vnode->fid.vnode, cmd,
811 fl->fl_type, fl->fl_flags);
812
813 /*
814 * No BSD flocks over NFS allowed.
815 * Note: we could try to fake a POSIX lock request here by
816 * using ((u32) filp | 0x80000000) or some such as the pid.
817 * Not sure whether that would be unique, though, or whether
818 * that would break in other places.
819 */
820 if (!(fl->fl_flags & FL_FLOCK))
821 return -ENOLCK;
822
823 fl->fl_u.afs.debug_id = atomic_inc_return(&afs_file_lock_debug_id);
824 trace_afs_flock_op(vnode, fl, afs_flock_op_flock);
825
826 /* we're simulating flock() locks using posix locks on the server */
827 if (fl->fl_type == F_UNLCK)
828 ret = afs_do_unlk(file, fl);
829 else
830 ret = afs_do_setlk(file, fl);
831
832 switch (ret) {
833 case 0: op = afs_flock_op_return_ok; break;
834 case -EAGAIN: op = afs_flock_op_return_eagain; break;
835 case -EDEADLK: op = afs_flock_op_return_edeadlk; break;
836 default: op = afs_flock_op_return_error; break;
837 }
838 trace_afs_flock_op(vnode, fl, op);
839 return ret;
840 }
841
842 /*
843 * the POSIX lock management core VFS code copies the lock record and adds the
844 * copy into its own list, so we need to add that copy to the vnode's lock
845 * queue in the same place as the original (which will be deleted shortly
846 * after)
847 */
afs_fl_copy_lock(struct file_lock * new,struct file_lock * fl)848 static void afs_fl_copy_lock(struct file_lock *new, struct file_lock *fl)
849 {
850 struct afs_vnode *vnode = AFS_FS_I(locks_inode(fl->fl_file));
851
852 _enter("");
853
854 new->fl_u.afs.debug_id = atomic_inc_return(&afs_file_lock_debug_id);
855
856 spin_lock(&vnode->lock);
857 trace_afs_flock_op(vnode, new, afs_flock_op_copy_lock);
858 list_add(&new->fl_u.afs.link, &fl->fl_u.afs.link);
859 spin_unlock(&vnode->lock);
860 }
861
862 /*
863 * need to remove this lock from the vnode queue when it's removed from the
864 * VFS's list
865 */
afs_fl_release_private(struct file_lock * fl)866 static void afs_fl_release_private(struct file_lock *fl)
867 {
868 struct afs_vnode *vnode = AFS_FS_I(locks_inode(fl->fl_file));
869
870 _enter("");
871
872 spin_lock(&vnode->lock);
873
874 trace_afs_flock_op(vnode, fl, afs_flock_op_release_lock);
875 list_del_init(&fl->fl_u.afs.link);
876 if (list_empty(&vnode->granted_locks))
877 afs_defer_unlock(vnode);
878
879 _debug("state %u for %p", vnode->lock_state, vnode);
880 spin_unlock(&vnode->lock);
881 }
882
