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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_vnode *vnode = call->lvnode;
74 
75 	if (call->error == 0) {
76 		spin_lock(&vnode->lock);
77 		trace_afs_flock_ev(vnode, NULL, afs_flock_timestamp, 0);
78 		vnode->locked_at = call->issue_time;
79 		afs_schedule_lock_extension(vnode);
80 		spin_unlock(&vnode->lock);
81 	}
82 }
83 
84 /*
85  * grant one or more locks (readlocks are allowed to jump the queue if the
86  * first lock in the queue is itself a readlock)
87  * - the caller must hold the vnode lock
88  */
afs_grant_locks(struct afs_vnode * vnode)89 static void afs_grant_locks(struct afs_vnode *vnode)
90 {
91 	struct file_lock *p, *_p;
92 	bool exclusive = (vnode->lock_type == AFS_LOCK_WRITE);
93 
94 	list_for_each_entry_safe(p, _p, &vnode->pending_locks, fl_u.afs.link) {
95 		if (!exclusive && p->fl_type == F_WRLCK)
96 			continue;
97 
98 		list_move_tail(&p->fl_u.afs.link, &vnode->granted_locks);
99 		p->fl_u.afs.state = AFS_LOCK_GRANTED;
100 		trace_afs_flock_op(vnode, p, afs_flock_op_grant);
101 		wake_up(&p->fl_wait);
102 	}
103 }
104 
105 /*
106  * If an error is specified, reject every pending lock that matches the
107  * authentication and type of the lock we failed to get.  If there are any
108  * remaining lockers, try to wake up one of them to have a go.
109  */
afs_next_locker(struct afs_vnode * vnode,int error)110 static void afs_next_locker(struct afs_vnode *vnode, int error)
111 {
112 	struct file_lock *p, *_p, *next = NULL;
113 	struct key *key = vnode->lock_key;
114 	unsigned int fl_type = F_RDLCK;
115 
116 	_enter("");
117 
118 	if (vnode->lock_type == AFS_LOCK_WRITE)
119 		fl_type = F_WRLCK;
120 
121 	list_for_each_entry_safe(p, _p, &vnode->pending_locks, fl_u.afs.link) {
122 		if (error &&
123 		    p->fl_type == fl_type &&
124 		    afs_file_key(p->fl_file) == key) {
125 			list_del_init(&p->fl_u.afs.link);
126 			p->fl_u.afs.state = error;
127 			wake_up(&p->fl_wait);
128 		}
129 
130 		/* Select the next locker to hand off to. */
131 		if (next &&
132 		    (next->fl_type == F_WRLCK || p->fl_type == F_RDLCK))
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 		wake_up(&next->fl_wait);
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  */
afs_kill_lockers_enoent(struct afs_vnode * vnode)157 static 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 		wake_up(&p->fl_wait);
169 	}
170 
171 	key_put(vnode->lock_key);
172 	vnode->lock_key = NULL;
173 }
174 
175 /*
176  * Get a lock on a file
177  */
afs_set_lock(struct afs_vnode * vnode,struct key * key,afs_lock_type_t type)178 static int afs_set_lock(struct afs_vnode *vnode, struct key *key,
179 			afs_lock_type_t type)
180 {
181 	struct afs_status_cb *scb;
182 	struct afs_fs_cursor fc;
183 	int ret;
184 
185 	_enter("%s{%llx:%llu.%u},%x,%u",
186 	       vnode->volume->name,
187 	       vnode->fid.vid,
188 	       vnode->fid.vnode,
189 	       vnode->fid.unique,
190 	       key_serial(key), type);
191 
192 	scb = kzalloc(sizeof(struct afs_status_cb), GFP_KERNEL);
193 	if (!scb)
194 		return -ENOMEM;
195 
196 	ret = -ERESTARTSYS;
197 	if (afs_begin_vnode_operation(&fc, vnode, key, true)) {
198 		while (afs_select_fileserver(&fc)) {
199 			fc.cb_break = afs_calc_vnode_cb_break(vnode);
200 			afs_fs_set_lock(&fc, type, scb);
201 		}
202 
203 		afs_check_for_remote_deletion(&fc, vnode);
204 		afs_vnode_commit_status(&fc, vnode, fc.cb_break, NULL, scb);
205 		ret = afs_end_vnode_operation(&fc);
206 	}
207 
208 	kfree(scb);
209 	_leave(" = %d", ret);
210 	return ret;
211 }
212 
213 /*
214  * Extend a lock on a file
215  */
afs_extend_lock(struct afs_vnode * vnode,struct key * key)216 static int afs_extend_lock(struct afs_vnode *vnode, struct key *key)
217 {
218 	struct afs_status_cb *scb;
219 	struct afs_fs_cursor fc;
220 	int ret;
221 
222 	_enter("%s{%llx:%llu.%u},%x",
223 	       vnode->volume->name,
224 	       vnode->fid.vid,
225 	       vnode->fid.vnode,
226 	       vnode->fid.unique,
227 	       key_serial(key));
228 
229 	scb = kzalloc(sizeof(struct afs_status_cb), GFP_KERNEL);
230 	if (!scb)
231 		return -ENOMEM;
232 
233 	ret = -ERESTARTSYS;
234 	if (afs_begin_vnode_operation(&fc, vnode, key, false)) {
235 		while (afs_select_current_fileserver(&fc)) {
236 			fc.cb_break = afs_calc_vnode_cb_break(vnode);
237 			afs_fs_extend_lock(&fc, scb);
238 		}
239 
240 		afs_check_for_remote_deletion(&fc, vnode);
241 		afs_vnode_commit_status(&fc, vnode, fc.cb_break, NULL, scb);
242 		ret = afs_end_vnode_operation(&fc);
243 	}
244 
245 	kfree(scb);
246 	_leave(" = %d", ret);
247 	return ret;
248 }
249 
250 /*
251  * Release a lock on a file
252  */
afs_release_lock(struct afs_vnode * vnode,struct key * key)253 static int afs_release_lock(struct afs_vnode *vnode, struct key *key)
254 {
255 	struct afs_status_cb *scb;
256 	struct afs_fs_cursor fc;
257 	int ret;
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 	scb = kzalloc(sizeof(struct afs_status_cb), GFP_KERNEL);
267 	if (!scb)
268 		return -ENOMEM;
269 
270 	ret = -ERESTARTSYS;
271 	if (afs_begin_vnode_operation(&fc, vnode, key, false)) {
272 		while (afs_select_current_fileserver(&fc)) {
273 			fc.cb_break = afs_calc_vnode_cb_break(vnode);
274 			afs_fs_release_lock(&fc, scb);
275 		}
276 
277 		afs_check_for_remote_deletion(&fc, vnode);
278 		afs_vnode_commit_status(&fc, vnode, fc.cb_break, NULL, scb);
279 		ret = afs_end_vnode_operation(&fc);
280 	}
281 
282 	kfree(scb);
283 	_leave(" = %d", ret);
284 	return ret;
285 }
286 
287 /*
288  * do work for a lock, including:
289  * - probing for a lock we're waiting on but didn't get immediately
290  * - extending a lock that's close to timing out
291  */
afs_lock_work(struct work_struct * work)292 void afs_lock_work(struct work_struct *work)
293 {
294 	struct afs_vnode *vnode =
295 		container_of(work, struct afs_vnode, lock_work.work);
296 	struct key *key;
297 	int ret;
298 
299 	_enter("{%llx:%llu}", vnode->fid.vid, vnode->fid.vnode);
300 
301 	spin_lock(&vnode->lock);
302 
303 again:
304 	_debug("wstate %u for %p", vnode->lock_state, vnode);
305 	switch (vnode->lock_state) {
306 	case AFS_VNODE_LOCK_NEED_UNLOCK:
307 		afs_set_lock_state(vnode, AFS_VNODE_LOCK_UNLOCKING);
308 		trace_afs_flock_ev(vnode, NULL, afs_flock_work_unlocking, 0);
309 		spin_unlock(&vnode->lock);
310 
311 		/* attempt to release the server lock; if it fails, we just
312 		 * wait 5 minutes and it'll expire anyway */
313 		ret = afs_release_lock(vnode, vnode->lock_key);
314 		if (ret < 0 && vnode->lock_state != AFS_VNODE_LOCK_DELETED) {
315 			trace_afs_flock_ev(vnode, NULL, afs_flock_release_fail,
316 					   ret);
317 			printk(KERN_WARNING "AFS:"
318 			       " Failed to release lock on {%llx:%llx} error %d\n",
319 			       vnode->fid.vid, vnode->fid.vnode, ret);
320 		}
321 
322 		spin_lock(&vnode->lock);
323 		if (ret == -ENOENT)
324 			afs_kill_lockers_enoent(vnode);
325 		else
326 			afs_next_locker(vnode, 0);
327 		spin_unlock(&vnode->lock);
328 		return;
329 
330 	/* If we've already got a lock, then it must be time to extend that
331 	 * lock as AFS locks time out after 5 minutes.
332 	 */
333 	case AFS_VNODE_LOCK_GRANTED:
334 		_debug("extend");
335 
336 		ASSERT(!list_empty(&vnode->granted_locks));
337 
338 		key = key_get(vnode->lock_key);
339 		afs_set_lock_state(vnode, AFS_VNODE_LOCK_EXTENDING);
340 		trace_afs_flock_ev(vnode, NULL, afs_flock_work_extending, 0);
341 		spin_unlock(&vnode->lock);
342 
343 		ret = afs_extend_lock(vnode, key); /* RPC */
344 		key_put(key);
345 
346 		if (ret < 0) {
347 			trace_afs_flock_ev(vnode, NULL, afs_flock_extend_fail,
348 					   ret);
349 			pr_warning("AFS: Failed to extend lock on {%llx:%llx} error %d\n",
350 				   vnode->fid.vid, vnode->fid.vnode, ret);
351 		}
352 
353 		spin_lock(&vnode->lock);
354 
355 		if (ret == -ENOENT) {
356 			afs_kill_lockers_enoent(vnode);
357 			spin_unlock(&vnode->lock);
358 			return;
359 		}
360 
361 		if (vnode->lock_state != AFS_VNODE_LOCK_EXTENDING)
362 			goto again;
363 		afs_set_lock_state(vnode, AFS_VNODE_LOCK_GRANTED);
364 
365 		if (ret != 0)
366 			queue_delayed_work(afs_lock_manager, &vnode->lock_work,
367 					   HZ * 10);
368 		spin_unlock(&vnode->lock);
369 		_leave(" [ext]");
370 		return;
371 
372 	/* If we're waiting for a callback to indicate lock release, we can't
373 	 * actually rely on this, so need to recheck at regular intervals.  The
374 	 * problem is that the server might not notify us if the lock just
375 	 * expires (say because a client died) rather than being explicitly
376 	 * released.
377 	 */
378 	case AFS_VNODE_LOCK_WAITING_FOR_CB:
379 		_debug("retry");
380 		afs_next_locker(vnode, 0);
381 		spin_unlock(&vnode->lock);
382 		return;
383 
384 	case AFS_VNODE_LOCK_DELETED:
385 		afs_kill_lockers_enoent(vnode);
386 		spin_unlock(&vnode->lock);
387 		return;
388 
389 		/* Fall through */
390 	default:
391 		/* Looks like a lock request was withdrawn. */
392 		spin_unlock(&vnode->lock);
393 		_leave(" [no]");
394 		return;
395 	}
396 }
397 
398 /*
399  * pass responsibility for the unlocking of a vnode on the server to the
400  * manager thread, lest a pending signal in the calling thread interrupt
401  * AF_RXRPC
402  * - the caller must hold the vnode lock
403  */
afs_defer_unlock(struct afs_vnode * vnode)404 static void afs_defer_unlock(struct afs_vnode *vnode)
405 {
406 	_enter("%u", vnode->lock_state);
407 
408 	if (list_empty(&vnode->granted_locks) &&
409 	    (vnode->lock_state == AFS_VNODE_LOCK_GRANTED ||
410 	     vnode->lock_state == AFS_VNODE_LOCK_EXTENDING)) {
411 		cancel_delayed_work(&vnode->lock_work);
412 
413 		afs_set_lock_state(vnode, AFS_VNODE_LOCK_NEED_UNLOCK);
414 		trace_afs_flock_ev(vnode, NULL, afs_flock_defer_unlock, 0);
415 		queue_delayed_work(afs_lock_manager, &vnode->lock_work, 0);
416 	}
417 }
418 
419 /*
420  * Check that our view of the file metadata is up to date and check to see
421  * whether we think that we have a locking permit.
422  */
afs_do_setlk_check(struct afs_vnode * vnode,struct key * key,enum afs_flock_mode mode,afs_lock_type_t type)423 static int afs_do_setlk_check(struct afs_vnode *vnode, struct key *key,
424 			      enum afs_flock_mode mode, afs_lock_type_t type)
425 {
426 	afs_access_t access;
427 	int ret;
428 
429 	/* Make sure we've got a callback on this file and that our view of the
430 	 * data version is up to date.
431 	 */
432 	ret = afs_validate(vnode, key);
433 	if (ret < 0)
434 		return ret;
435 
436 	/* Check the permission set to see if we're actually going to be
437 	 * allowed to get a lock on this file.
438 	 */
439 	ret = afs_check_permit(vnode, key, &access);
440 	if (ret < 0)
441 		return ret;
442 
443 	/* At a rough estimation, you need LOCK, WRITE or INSERT perm to
444 	 * read-lock a file and WRITE or INSERT perm to write-lock a file.
445 	 *
446 	 * We can't rely on the server to do this for us since if we want to
447 	 * share a read lock that we already have, we won't go the server.
448 	 */
449 	if (type == AFS_LOCK_READ) {
450 		if (!(access & (AFS_ACE_INSERT | AFS_ACE_WRITE | AFS_ACE_LOCK)))
451 			return -EACCES;
452 	} else {
453 		if (!(access & (AFS_ACE_INSERT | AFS_ACE_WRITE)))
454 			return -EACCES;
455 	}
456 
457 	return 0;
458 }
459 
460 /*
461  * request a lock on a file on the server
462  */
afs_do_setlk(struct file * file,struct file_lock * fl)463 static int afs_do_setlk(struct file *file, struct file_lock *fl)
464 {
465 	struct inode *inode = locks_inode(file);
466 	struct afs_vnode *vnode = AFS_FS_I(inode);
467 	enum afs_flock_mode mode = AFS_FS_S(inode->i_sb)->flock_mode;
468 	afs_lock_type_t type;
469 	struct key *key = afs_file_key(file);
470 	bool partial, no_server_lock = false;
471 	int ret;
472 
473 	if (mode == afs_flock_mode_unset)
474 		mode = afs_flock_mode_openafs;
475 
476 	_enter("{%llx:%llu},%llu-%llu,%u,%u",
477 	       vnode->fid.vid, vnode->fid.vnode,
478 	       fl->fl_start, fl->fl_end, fl->fl_type, mode);
479 
480 	fl->fl_ops = &afs_lock_ops;
481 	INIT_LIST_HEAD(&fl->fl_u.afs.link);
482 	fl->fl_u.afs.state = AFS_LOCK_PENDING;
483 
484 	partial = (fl->fl_start != 0 || fl->fl_end != OFFSET_MAX);
485 	type = (fl->fl_type == F_RDLCK) ? AFS_LOCK_READ : AFS_LOCK_WRITE;
486 	if (mode == afs_flock_mode_write && partial)
487 		type = AFS_LOCK_WRITE;
488 
489 	ret = afs_do_setlk_check(vnode, key, mode, type);
490 	if (ret < 0)
491 		return ret;
492 
493 	trace_afs_flock_op(vnode, fl, afs_flock_op_set_lock);
494 
495 	/* AFS3 protocol only supports full-file locks and doesn't provide any
496 	 * method of upgrade/downgrade, so we need to emulate for partial-file
497 	 * locks.
498 	 *
499 	 * The OpenAFS client only gets a server lock for a full-file lock and
500 	 * keeps partial-file locks local.  Allow this behaviour to be emulated
501 	 * (as the default).
502 	 */
503 	if (mode == afs_flock_mode_local ||
504 	    (partial && mode == afs_flock_mode_openafs)) {
505 		no_server_lock = true;
506 		goto skip_server_lock;
507 	}
508 
509 	spin_lock(&vnode->lock);
510 	list_add_tail(&fl->fl_u.afs.link, &vnode->pending_locks);
511 
512 	ret = -ENOENT;
513 	if (vnode->lock_state == AFS_VNODE_LOCK_DELETED)
514 		goto error_unlock;
515 
516 	/* If we've already got a lock on the server then try to move to having
517 	 * the VFS grant the requested lock.  Note that this means that other
518 	 * clients may get starved out.
519 	 */
520 	_debug("try %u", vnode->lock_state);
521 	if (vnode->lock_state == AFS_VNODE_LOCK_GRANTED) {
522 		if (type == AFS_LOCK_READ) {
523 			_debug("instant readlock");
524 			list_move_tail(&fl->fl_u.afs.link, &vnode->granted_locks);
525 			fl->fl_u.afs.state = AFS_LOCK_GRANTED;
526 			goto vnode_is_locked_u;
527 		}
528 
529 		if (vnode->lock_type == AFS_LOCK_WRITE) {
530 			_debug("instant writelock");
531 			list_move_tail(&fl->fl_u.afs.link, &vnode->granted_locks);
532 			fl->fl_u.afs.state = AFS_LOCK_GRANTED;
533 			goto vnode_is_locked_u;
534 		}
535 	}
536 
537 	if (vnode->lock_state == AFS_VNODE_LOCK_NONE &&
538 	    !(fl->fl_flags & FL_SLEEP)) {
539 		ret = -EAGAIN;
540 		if (type == AFS_LOCK_READ) {
541 			if (vnode->status.lock_count == -1)
542 				goto lock_is_contended; /* Write locked */
543 		} else {
544 			if (vnode->status.lock_count != 0)
545 				goto lock_is_contended; /* Locked */
546 		}
547 	}
548 
549 	if (vnode->lock_state != AFS_VNODE_LOCK_NONE)
550 		goto need_to_wait;
551 
552 try_to_lock:
553 	/* We don't have a lock on this vnode and we aren't currently waiting
554 	 * for one either, so ask the server for a lock.
555 	 *
556 	 * Note that we need to be careful if we get interrupted by a signal
557 	 * after dispatching the request as we may still get the lock, even
558 	 * though we don't wait for the reply (it's not too bad a problem - the
559 	 * lock will expire in 5 mins anyway).
560 	 */
561 	trace_afs_flock_ev(vnode, fl, afs_flock_try_to_lock, 0);
562 	vnode->lock_key = key_get(key);
563 	vnode->lock_type = type;
564 	afs_set_lock_state(vnode, AFS_VNODE_LOCK_SETTING);
565 	spin_unlock(&vnode->lock);
566 
567 	ret = afs_set_lock(vnode, key, type); /* RPC */
568 
569 	spin_lock(&vnode->lock);
570 	switch (ret) {
571 	case -EKEYREJECTED:
572 	case -EKEYEXPIRED:
573 	case -EKEYREVOKED:
574 	case -EPERM:
575 	case -EACCES:
576 		fl->fl_u.afs.state = ret;
577 		trace_afs_flock_ev(vnode, fl, afs_flock_fail_perm, ret);
578 		list_del_init(&fl->fl_u.afs.link);
579 		afs_next_locker(vnode, ret);
580 		goto error_unlock;
581 
582 	case -ENOENT:
583 		fl->fl_u.afs.state = ret;
584 		trace_afs_flock_ev(vnode, fl, afs_flock_fail_other, ret);
585 		list_del_init(&fl->fl_u.afs.link);
586 		afs_kill_lockers_enoent(vnode);
587 		goto error_unlock;
588 
589 	default:
590 		fl->fl_u.afs.state = ret;
591 		trace_afs_flock_ev(vnode, fl, afs_flock_fail_other, ret);
592 		list_del_init(&fl->fl_u.afs.link);
593 		afs_next_locker(vnode, 0);
594 		goto error_unlock;
595 
596 	case -EWOULDBLOCK:
597 		/* The server doesn't have a lock-waiting queue, so the client
598 		 * will have to retry.  The server will break the outstanding
599 		 * callbacks on a file when a lock is released.
600 		 */
601 		ASSERT(list_empty(&vnode->granted_locks));
602 		ASSERTCMP(vnode->pending_locks.next, ==, &fl->fl_u.afs.link);
603 		goto lock_is_contended;
604 
605 	case 0:
606 		afs_set_lock_state(vnode, AFS_VNODE_LOCK_GRANTED);
607 		trace_afs_flock_ev(vnode, fl, afs_flock_acquired, type);
608 		afs_grant_locks(vnode);
609 		goto vnode_is_locked_u;
610 	}
611 
612 vnode_is_locked_u:
613 	spin_unlock(&vnode->lock);
614 vnode_is_locked:
615 	/* the lock has been granted by the server... */
616 	ASSERTCMP(fl->fl_u.afs.state, ==, AFS_LOCK_GRANTED);
617 
618 skip_server_lock:
619 	/* ... but the VFS still needs to distribute access on this client. */
620 	trace_afs_flock_ev(vnode, fl, afs_flock_vfs_locking, 0);
621 	ret = locks_lock_file_wait(file, fl);
622 	trace_afs_flock_ev(vnode, fl, afs_flock_vfs_lock, ret);
623 	if (ret < 0)
624 		goto vfs_rejected_lock;
625 
626 	/* Again, make sure we've got a callback on this file and, again, make
627 	 * sure that our view of the data version is up to date (we ignore
628 	 * errors incurred here and deal with the consequences elsewhere).
629 	 */
630 	afs_validate(vnode, key);
631 	_leave(" = 0");
632 	return 0;
633 
634 lock_is_contended:
635 	if (!(fl->fl_flags & FL_SLEEP)) {
636 		list_del_init(&fl->fl_u.afs.link);
637 		afs_next_locker(vnode, 0);
638 		ret = -EAGAIN;
639 		goto error_unlock;
640 	}
641 
642 	afs_set_lock_state(vnode, AFS_VNODE_LOCK_WAITING_FOR_CB);
643 	trace_afs_flock_ev(vnode, fl, afs_flock_would_block, ret);
644 	queue_delayed_work(afs_lock_manager, &vnode->lock_work, HZ * 5);
645 
646 need_to_wait:
647 	/* We're going to have to wait.  Either this client doesn't have a lock
648 	 * on the server yet and we need to wait for a callback to occur, or
649 	 * the client does have a lock on the server, but it's shared and we
650 	 * need an exclusive lock.
651 	 */
652 	spin_unlock(&vnode->lock);
653 
654 	trace_afs_flock_ev(vnode, fl, afs_flock_waiting, 0);
655 	ret = wait_event_interruptible(fl->fl_wait,
656 				       fl->fl_u.afs.state != AFS_LOCK_PENDING);
657 	trace_afs_flock_ev(vnode, fl, afs_flock_waited, ret);
658 
659 	if (fl->fl_u.afs.state >= 0 && fl->fl_u.afs.state != AFS_LOCK_GRANTED) {
660 		spin_lock(&vnode->lock);
661 
662 		switch (fl->fl_u.afs.state) {
663 		case AFS_LOCK_YOUR_TRY:
664 			fl->fl_u.afs.state = AFS_LOCK_PENDING;
665 			goto try_to_lock;
666 		case AFS_LOCK_PENDING:
667 			if (ret > 0) {
668 				/* We need to retry the lock.  We may not be
669 				 * notified by the server if it just expired
670 				 * rather than being released.
671 				 */
672 				ASSERTCMP(vnode->lock_state, ==, AFS_VNODE_LOCK_WAITING_FOR_CB);
673 				afs_set_lock_state(vnode, AFS_VNODE_LOCK_SETTING);
674 				fl->fl_u.afs.state = AFS_LOCK_PENDING;
675 				goto try_to_lock;
676 			}
677 			goto error_unlock;
678 		case AFS_LOCK_GRANTED:
679 		default:
680 			break;
681 		}
682 
683 		spin_unlock(&vnode->lock);
684 	}
685 
686 	if (fl->fl_u.afs.state == AFS_LOCK_GRANTED)
687 		goto vnode_is_locked;
688 	ret = fl->fl_u.afs.state;
689 	goto error;
690 
691 vfs_rejected_lock:
692 	/* The VFS rejected the lock we just obtained, so we have to discard
693 	 * what we just got.  We defer this to the lock manager work item to
694 	 * deal with.
695 	 */
696 	_debug("vfs refused %d", ret);
697 	if (no_server_lock)
698 		goto error;
699 	spin_lock(&vnode->lock);
700 	list_del_init(&fl->fl_u.afs.link);
701 	afs_defer_unlock(vnode);
702 
703 error_unlock:
704 	spin_unlock(&vnode->lock);
705 error:
706 	_leave(" = %d", ret);
707 	return ret;
708 }
709 
710 /*
711  * unlock on a file on the server
712  */
afs_do_unlk(struct file * file,struct file_lock * fl)713 static int afs_do_unlk(struct file *file, struct file_lock *fl)
714 {
715 	struct afs_vnode *vnode = AFS_FS_I(locks_inode(file));
716 	int ret;
717 
718 	_enter("{%llx:%llu},%u", vnode->fid.vid, vnode->fid.vnode, fl->fl_type);
719 
720 	trace_afs_flock_op(vnode, fl, afs_flock_op_unlock);
721 
722 	/* Flush all pending writes before doing anything with locks. */
723 	vfs_fsync(file, 0);
724 
725 	ret = locks_lock_file_wait(file, fl);
726 	_leave(" = %d [%u]", ret, vnode->lock_state);
727 	return ret;
728 }
729 
730 /*
731  * return information about a lock we currently hold, if indeed we hold one
732  */
afs_do_getlk(struct file * file,struct file_lock * fl)733 static int afs_do_getlk(struct file *file, struct file_lock *fl)
734 {
735 	struct afs_vnode *vnode = AFS_FS_I(locks_inode(file));
736 	struct key *key = afs_file_key(file);
737 	int ret, lock_count;
738 
739 	_enter("");
740 
741 	if (vnode->lock_state == AFS_VNODE_LOCK_DELETED)
742 		return -ENOENT;
743 
744 	fl->fl_type = F_UNLCK;
745 
746 	/* check local lock records first */
747 	posix_test_lock(file, fl);
748 	if (fl->fl_type == F_UNLCK) {
749 		/* no local locks; consult the server */
750 		ret = afs_fetch_status(vnode, key, false, NULL);
751 		if (ret < 0)
752 			goto error;
753 
754 		lock_count = READ_ONCE(vnode->status.lock_count);
755 		if (lock_count != 0) {
756 			if (lock_count > 0)
757 				fl->fl_type = F_RDLCK;
758 			else
759 				fl->fl_type = F_WRLCK;
760 			fl->fl_start = 0;
761 			fl->fl_end = OFFSET_MAX;
762 			fl->fl_pid = 0;
763 		}
764 	}
765 
766 	ret = 0;
767 error:
768 	_leave(" = %d [%hd]", ret, fl->fl_type);
769 	return ret;
770 }
771 
772 /*
773  * manage POSIX locks on a file
774  */
afs_lock(struct file * file,int cmd,struct file_lock * fl)775 int afs_lock(struct file *file, int cmd, struct file_lock *fl)
776 {
777 	struct afs_vnode *vnode = AFS_FS_I(locks_inode(file));
778 	enum afs_flock_operation op;
779 	int ret;
780 
781 	_enter("{%llx:%llu},%d,{t=%x,fl=%x,r=%Ld:%Ld}",
782 	       vnode->fid.vid, vnode->fid.vnode, cmd,
783 	       fl->fl_type, fl->fl_flags,
784 	       (long long) fl->fl_start, (long long) fl->fl_end);
785 
786 	/* AFS doesn't support mandatory locks */
787 	if (__mandatory_lock(&vnode->vfs_inode) && fl->fl_type != F_UNLCK)
788 		return -ENOLCK;
789 
790 	if (IS_GETLK(cmd))
791 		return afs_do_getlk(file, fl);
792 
793 	fl->fl_u.afs.debug_id = atomic_inc_return(&afs_file_lock_debug_id);
794 	trace_afs_flock_op(vnode, fl, afs_flock_op_lock);
795 
796 	if (fl->fl_type == F_UNLCK)
797 		ret = afs_do_unlk(file, fl);
798 	else
799 		ret = afs_do_setlk(file, fl);
800 
801 	switch (ret) {
802 	case 0:		op = afs_flock_op_return_ok; break;
803 	case -EAGAIN:	op = afs_flock_op_return_eagain; break;
804 	case -EDEADLK:	op = afs_flock_op_return_edeadlk; break;
805 	default:	op = afs_flock_op_return_error; break;
806 	}
807 	trace_afs_flock_op(vnode, fl, op);
808 	return ret;
809 }
810 
811 /*
812  * manage FLOCK locks on a file
813  */
afs_flock(struct file * file,int cmd,struct file_lock * fl)814 int afs_flock(struct file *file, int cmd, struct file_lock *fl)
815 {
816 	struct afs_vnode *vnode = AFS_FS_I(locks_inode(file));
817 	enum afs_flock_operation op;
818 	int ret;
819 
820 	_enter("{%llx:%llu},%d,{t=%x,fl=%x}",
821 	       vnode->fid.vid, vnode->fid.vnode, cmd,
822 	       fl->fl_type, fl->fl_flags);
823 
824 	/*
825 	 * No BSD flocks over NFS allowed.
826 	 * Note: we could try to fake a POSIX lock request here by
827 	 * using ((u32) filp | 0x80000000) or some such as the pid.
828 	 * Not sure whether that would be unique, though, or whether
829 	 * that would break in other places.
830 	 */
831 	if (!(fl->fl_flags & FL_FLOCK))
832 		return -ENOLCK;
833 
834 	fl->fl_u.afs.debug_id = atomic_inc_return(&afs_file_lock_debug_id);
835 	trace_afs_flock_op(vnode, fl, afs_flock_op_flock);
836 
837 	/* we're simulating flock() locks using posix locks on the server */
838 	if (fl->fl_type == F_UNLCK)
839 		ret = afs_do_unlk(file, fl);
840 	else
841 		ret = afs_do_setlk(file, fl);
842 
843 	switch (ret) {
844 	case 0:		op = afs_flock_op_return_ok; break;
845 	case -EAGAIN:	op = afs_flock_op_return_eagain; break;
846 	case -EDEADLK:	op = afs_flock_op_return_edeadlk; break;
847 	default:	op = afs_flock_op_return_error; break;
848 	}
849 	trace_afs_flock_op(vnode, fl, op);
850 	return ret;
851 }
852 
853 /*
854  * the POSIX lock management core VFS code copies the lock record and adds the
855  * copy into its own list, so we need to add that copy to the vnode's lock
856  * queue in the same place as the original (which will be deleted shortly
857  * after)
858  */
afs_fl_copy_lock(struct file_lock * new,struct file_lock * fl)859 static void afs_fl_copy_lock(struct file_lock *new, struct file_lock *fl)
860 {
861 	struct afs_vnode *vnode = AFS_FS_I(locks_inode(fl->fl_file));
862 
863 	_enter("");
864 
865 	new->fl_u.afs.debug_id = atomic_inc_return(&afs_file_lock_debug_id);
866 
867 	spin_lock(&vnode->lock);
868 	trace_afs_flock_op(vnode, new, afs_flock_op_copy_lock);
869 	list_add(&new->fl_u.afs.link, &fl->fl_u.afs.link);
870 	spin_unlock(&vnode->lock);
871 }
872 
873 /*
874  * need to remove this lock from the vnode queue when it's removed from the
875  * VFS's list
876  */
afs_fl_release_private(struct file_lock * fl)877 static void afs_fl_release_private(struct file_lock *fl)
878 {
879 	struct afs_vnode *vnode = AFS_FS_I(locks_inode(fl->fl_file));
880 
881 	_enter("");
882 
883 	spin_lock(&vnode->lock);
884 
885 	trace_afs_flock_op(vnode, fl, afs_flock_op_release_lock);
886 	list_del_init(&fl->fl_u.afs.link);
887 	if (list_empty(&vnode->granted_locks))
888 		afs_defer_unlock(vnode);
889 
890 	_debug("state %u for %p", vnode->lock_state, vnode);
891 	spin_unlock(&vnode->lock);
892 }
893