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