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 && 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 */
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 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 */
158static 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
176static 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
182static 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 */
192static 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
215static 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 */
224static 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
246static 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 */
255static 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 */
282void 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
293again:
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 */
393static 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 */
412static 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 */
452static 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
541try_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
601vnode_is_locked_u:
602	spin_unlock(&vnode->lock);
603vnode_is_locked:
604	/* the lock has been granted by the server... */
605	ASSERTCMP(fl->fl_u.afs.state, ==, AFS_LOCK_GRANTED);
606
607skip_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
623lock_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
635need_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
680vfs_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
692error_unlock:
693	spin_unlock(&vnode->lock);
694error:
695	_leave(" = %d", ret);
696	return ret;
697}
698
699/*
700 * unlock on a file on the server
701 */
702static 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 */
722static 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;
756error:
757	_leave(" = %d [%hd]", ret, fl->fl_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(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	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 (fl->fl_type == F_UNLCK)
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(locks_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->fl_type, fl->fl_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->fl_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 (fl->fl_type == F_UNLCK)
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(locks_inode(fl->fl_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(locks_inode(fl->fl_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}