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TOMOYO Linux Cross Reference
Linux/fs/afs/flock.c

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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 
 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  */
 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  */
 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  */
 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->reply_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  */
 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  */
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  */
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  */
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  */
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  */
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  */
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_warn("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  */
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  */
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  */
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  */
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  */
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  */
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  */
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  */
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  */
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 

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