1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Copyright (C) 2005-2008 Red Hat, Inc. All rights reserved.
4 */
5
6 #include <linux/fs.h>
7 #include <linux/filelock.h>
8 #include <linux/miscdevice.h>
9 #include <linux/poll.h>
10 #include <linux/dlm.h>
11 #include <linux/dlm_plock.h>
12 #include <linux/slab.h>
13
14 #include <trace/events/dlm.h>
15
16 #include "dlm_internal.h"
17 #include "lockspace.h"
18
19 static DEFINE_SPINLOCK(ops_lock);
20 static LIST_HEAD(send_list);
21 static LIST_HEAD(recv_list);
22 static DECLARE_WAIT_QUEUE_HEAD(send_wq);
23 static DECLARE_WAIT_QUEUE_HEAD(recv_wq);
24
25 struct plock_async_data {
26 void *fl;
27 void *file;
28 struct file_lock flc;
29 int (*callback)(struct file_lock *fl, int result);
30 };
31
32 struct plock_op {
33 struct list_head list;
34 int done;
35 struct dlm_plock_info info;
36 /* if set indicates async handling */
37 struct plock_async_data *data;
38 };
39
40 static inline void set_version(struct dlm_plock_info *info)
41 {
42 info->version[0] = DLM_PLOCK_VERSION_MAJOR;
43 info->version[1] = DLM_PLOCK_VERSION_MINOR;
44 info->version[2] = DLM_PLOCK_VERSION_PATCH;
45 }
46
47 static struct plock_op *plock_lookup_waiter(const struct dlm_plock_info *info)
48 {
49 struct plock_op *op = NULL, *iter;
50
51 list_for_each_entry(iter, &recv_list, list) {
52 if (iter->info.fsid == info->fsid &&
53 iter->info.number == info->number &&
54 iter->info.owner == info->owner &&
55 iter->info.pid == info->pid &&
56 iter->info.start == info->start &&
57 iter->info.end == info->end &&
58 iter->info.ex == info->ex &&
59 iter->info.wait) {
60 op = iter;
61 break;
62 }
63 }
64
65 return op;
66 }
67
68 static int check_version(struct dlm_plock_info *info)
69 {
70 if ((DLM_PLOCK_VERSION_MAJOR != info->version[0]) ||
71 (DLM_PLOCK_VERSION_MINOR < info->version[1])) {
72 log_print("plock device version mismatch: "
73 "kernel (%u.%u.%u), user (%u.%u.%u)",
74 DLM_PLOCK_VERSION_MAJOR,
75 DLM_PLOCK_VERSION_MINOR,
76 DLM_PLOCK_VERSION_PATCH,
77 info->version[0],
78 info->version[1],
79 info->version[2]);
80 return -EINVAL;
81 }
82 return 0;
83 }
84
85 static void dlm_release_plock_op(struct plock_op *op)
86 {
87 kfree(op->data);
88 kfree(op);
89 }
90
91 static void send_op(struct plock_op *op)
92 {
93 set_version(&op->info);
94 spin_lock(&ops_lock);
95 list_add_tail(&op->list, &send_list);
96 spin_unlock(&ops_lock);
97 wake_up(&send_wq);
98 }
99
100 static int do_lock_cancel(const struct dlm_plock_info *orig_info)
101 {
102 struct plock_op *op;
103 int rv;
104
105 op = kzalloc(sizeof(*op), GFP_NOFS);
106 if (!op)
107 return -ENOMEM;
108
109 op->info = *orig_info;
110 op->info.optype = DLM_PLOCK_OP_CANCEL;
111 op->info.wait = 0;
112
113 send_op(op);
114 wait_event(recv_wq, (op->done != 0));
115
116 rv = op->info.rv;
117
118 dlm_release_plock_op(op);
119 return rv;
120 }
121
122 int dlm_posix_lock(dlm_lockspace_t *lockspace, u64 number, struct file *file,
123 int cmd, struct file_lock *fl)
124 {
125 struct plock_async_data *op_data;
126 struct dlm_ls *ls;
127 struct plock_op *op;
128 int rv;
129
130 ls = dlm_find_lockspace_local(lockspace);
131 if (!ls)
132 return -EINVAL;
133
134 op = kzalloc(sizeof(*op), GFP_NOFS);
135 if (!op) {
136 rv = -ENOMEM;
137 goto out;
138 }
139
140 op->info.optype = DLM_PLOCK_OP_LOCK;
141 op->info.pid = fl->c.flc_pid;
142 op->info.ex = lock_is_write(fl);
143 op->info.wait = !!(fl->c.flc_flags & FL_SLEEP);
144 op->info.fsid = ls->ls_global_id;
145 op->info.number = number;
146 op->info.start = fl->fl_start;
147 op->info.end = fl->fl_end;
148 op->info.owner = (__u64)(long) fl->c.flc_owner;
149 /* async handling */
150 if (fl->fl_lmops && fl->fl_lmops->lm_grant) {
151 op_data = kzalloc(sizeof(*op_data), GFP_NOFS);
152 if (!op_data) {
153 dlm_release_plock_op(op);
154 rv = -ENOMEM;
155 goto out;
156 }
157
158 op_data->callback = fl->fl_lmops->lm_grant;
159 locks_init_lock(&op_data->flc);
160 locks_copy_lock(&op_data->flc, fl);
161 op_data->fl = fl;
162 op_data->file = file;
163
164 op->data = op_data;
165
166 send_op(op);
167 rv = FILE_LOCK_DEFERRED;
168 goto out;
169 }
170
171 send_op(op);
172
173 if (op->info.wait) {
174 rv = wait_event_interruptible(recv_wq, (op->done != 0));
175 if (rv == -ERESTARTSYS) {
176 spin_lock(&ops_lock);
177 /* recheck under ops_lock if we got a done != 0,
178 * if so this interrupt case should be ignored
179 */
180 if (op->done != 0) {
181 spin_unlock(&ops_lock);
182 goto do_lock_wait;
183 }
184 spin_unlock(&ops_lock);
185
186 rv = do_lock_cancel(&op->info);
187 switch (rv) {
188 case 0:
189 /* waiter was deleted in user space, answer will never come
190 * remove original request. The original request must be
191 * on recv_list because the answer of do_lock_cancel()
192 * synchronized it.
193 */
194 spin_lock(&ops_lock);
195 list_del(&op->list);
196 spin_unlock(&ops_lock);
197 rv = -EINTR;
198 break;
199 case -ENOENT:
200 /* cancellation wasn't successful but op should be done */
201 fallthrough;
202 default:
203 /* internal error doing cancel we need to wait */
204 goto wait;
205 }
206
207 log_debug(ls, "%s: wait interrupted %x %llx pid %d",
208 __func__, ls->ls_global_id,
209 (unsigned long long)number, op->info.pid);
210 dlm_release_plock_op(op);
211 goto out;
212 }
213 } else {
214 wait:
215 wait_event(recv_wq, (op->done != 0));
216 }
217
218 do_lock_wait:
219
220 WARN_ON(!list_empty(&op->list));
221
222 rv = op->info.rv;
223
224 if (!rv) {
225 if (locks_lock_file_wait(file, fl) < 0)
226 log_error(ls, "dlm_posix_lock: vfs lock error %llx",
227 (unsigned long long)number);
228 }
229
230 dlm_release_plock_op(op);
231 out:
232 dlm_put_lockspace(ls);
233 return rv;
234 }
235 EXPORT_SYMBOL_GPL(dlm_posix_lock);
236
237 /* Returns failure iff a successful lock operation should be canceled */
238 static int dlm_plock_callback(struct plock_op *op)
239 {
240 struct plock_async_data *op_data = op->data;
241 struct file *file;
242 struct file_lock *fl;
243 struct file_lock *flc;
244 int (*notify)(struct file_lock *fl, int result) = NULL;
245 int rv = 0;
246
247 WARN_ON(!list_empty(&op->list));
248
249 /* check if the following 2 are still valid or make a copy */
250 file = op_data->file;
251 flc = &op_data->flc;
252 fl = op_data->fl;
253 notify = op_data->callback;
254
255 if (op->info.rv) {
256 notify(fl, op->info.rv);
257 goto out;
258 }
259
260 /* got fs lock; bookkeep locally as well: */
261 flc->c.flc_flags &= ~FL_SLEEP;
262 if (posix_lock_file(file, flc, NULL)) {
263 /*
264 * This can only happen in the case of kmalloc() failure.
265 * The filesystem's own lock is the authoritative lock,
266 * so a failure to get the lock locally is not a disaster.
267 * As long as the fs cannot reliably cancel locks (especially
268 * in a low-memory situation), we're better off ignoring
269 * this failure than trying to recover.
270 */
271 log_print("dlm_plock_callback: vfs lock error %llx file %p fl %p",
272 (unsigned long long)op->info.number, file, fl);
273 }
274
275 rv = notify(fl, 0);
276 if (rv) {
277 /* XXX: We need to cancel the fs lock here: */
278 log_print("%s: lock granted after lock request failed; dangling lock!",
279 __func__);
280 goto out;
281 }
282
283 out:
284 dlm_release_plock_op(op);
285 return rv;
286 }
287
288 int dlm_posix_unlock(dlm_lockspace_t *lockspace, u64 number, struct file *file,
289 struct file_lock *fl)
290 {
291 struct dlm_ls *ls;
292 struct plock_op *op;
293 int rv;
294 unsigned char saved_flags = fl->c.flc_flags;
295
296 ls = dlm_find_lockspace_local(lockspace);
297 if (!ls)
298 return -EINVAL;
299
300 op = kzalloc(sizeof(*op), GFP_NOFS);
301 if (!op) {
302 rv = -ENOMEM;
303 goto out;
304 }
305
306 /* cause the vfs unlock to return ENOENT if lock is not found */
307 fl->c.flc_flags |= FL_EXISTS;
308
309 rv = locks_lock_file_wait(file, fl);
310 if (rv == -ENOENT) {
311 rv = 0;
312 goto out_free;
313 }
314 if (rv < 0) {
315 log_error(ls, "dlm_posix_unlock: vfs unlock error %d %llx",
316 rv, (unsigned long long)number);
317 }
318
319 op->info.optype = DLM_PLOCK_OP_UNLOCK;
320 op->info.pid = fl->c.flc_pid;
321 op->info.fsid = ls->ls_global_id;
322 op->info.number = number;
323 op->info.start = fl->fl_start;
324 op->info.end = fl->fl_end;
325 op->info.owner = (__u64)(long) fl->c.flc_owner;
326
327 if (fl->c.flc_flags & FL_CLOSE) {
328 op->info.flags |= DLM_PLOCK_FL_CLOSE;
329 send_op(op);
330 rv = 0;
331 goto out;
332 }
333
334 send_op(op);
335 wait_event(recv_wq, (op->done != 0));
336
337 WARN_ON(!list_empty(&op->list));
338
339 rv = op->info.rv;
340
341 if (rv == -ENOENT)
342 rv = 0;
343
344 out_free:
345 dlm_release_plock_op(op);
346 out:
347 dlm_put_lockspace(ls);
348 fl->c.flc_flags = saved_flags;
349 return rv;
350 }
351 EXPORT_SYMBOL_GPL(dlm_posix_unlock);
352
353 /*
354 * NOTE: This implementation can only handle async lock requests as nfs
355 * do it. It cannot handle cancellation of a pending lock request sitting
356 * in wait_event(), but for now only nfs is the only user local kernel
357 * user.
358 */
359 int dlm_posix_cancel(dlm_lockspace_t *lockspace, u64 number, struct file *file,
360 struct file_lock *fl)
361 {
362 struct dlm_plock_info info;
363 struct plock_op *op;
364 struct dlm_ls *ls;
365 int rv;
366
367 /* this only works for async request for now and nfs is the only
368 * kernel user right now.
369 */
370 if (WARN_ON_ONCE(!fl->fl_lmops || !fl->fl_lmops->lm_grant))
371 return -EOPNOTSUPP;
372
373 ls = dlm_find_lockspace_local(lockspace);
374 if (!ls)
375 return -EINVAL;
376
377 memset(&info, 0, sizeof(info));
378 info.pid = fl->c.flc_pid;
379 info.ex = lock_is_write(fl);
380 info.fsid = ls->ls_global_id;
381 dlm_put_lockspace(ls);
382 info.number = number;
383 info.start = fl->fl_start;
384 info.end = fl->fl_end;
385 info.owner = (__u64)(long) fl->c.flc_owner;
386
387 rv = do_lock_cancel(&info);
388 switch (rv) {
389 case 0:
390 spin_lock(&ops_lock);
391 /* lock request to cancel must be on recv_list because
392 * do_lock_cancel() synchronizes it.
393 */
394 op = plock_lookup_waiter(&info);
395 if (WARN_ON_ONCE(!op)) {
396 spin_unlock(&ops_lock);
397 rv = -ENOLCK;
398 break;
399 }
400
401 list_del(&op->list);
402 spin_unlock(&ops_lock);
403 WARN_ON(op->info.optype != DLM_PLOCK_OP_LOCK);
404 op->data->callback(op->data->fl, -EINTR);
405 dlm_release_plock_op(op);
406 rv = -EINTR;
407 break;
408 case -ENOENT:
409 /* if cancel wasn't successful we probably were to late
410 * or it was a non-blocking lock request, so just unlock it.
411 */
412 rv = dlm_posix_unlock(lockspace, number, file, fl);
413 break;
414 default:
415 break;
416 }
417
418 return rv;
419 }
420 EXPORT_SYMBOL_GPL(dlm_posix_cancel);
421
422 int dlm_posix_get(dlm_lockspace_t *lockspace, u64 number, struct file *file,
423 struct file_lock *fl)
424 {
425 struct dlm_ls *ls;
426 struct plock_op *op;
427 int rv;
428
429 ls = dlm_find_lockspace_local(lockspace);
430 if (!ls)
431 return -EINVAL;
432
433 op = kzalloc(sizeof(*op), GFP_NOFS);
434 if (!op) {
435 rv = -ENOMEM;
436 goto out;
437 }
438
439 op->info.optype = DLM_PLOCK_OP_GET;
440 op->info.pid = fl->c.flc_pid;
441 op->info.ex = lock_is_write(fl);
442 op->info.fsid = ls->ls_global_id;
443 op->info.number = number;
444 op->info.start = fl->fl_start;
445 op->info.end = fl->fl_end;
446 op->info.owner = (__u64)(long) fl->c.flc_owner;
447
448 send_op(op);
449 wait_event(recv_wq, (op->done != 0));
450
451 WARN_ON(!list_empty(&op->list));
452
453 /* info.rv from userspace is 1 for conflict, 0 for no-conflict,
454 -ENOENT if there are no locks on the file */
455
456 rv = op->info.rv;
457
458 fl->c.flc_type = F_UNLCK;
459 if (rv == -ENOENT)
460 rv = 0;
461 else if (rv > 0) {
462 locks_init_lock(fl);
463 fl->c.flc_type = (op->info.ex) ? F_WRLCK : F_RDLCK;
464 fl->c.flc_flags = FL_POSIX;
465 fl->c.flc_pid = op->info.pid;
466 if (op->info.nodeid != dlm_our_nodeid())
467 fl->c.flc_pid = -fl->c.flc_pid;
468 fl->fl_start = op->info.start;
469 fl->fl_end = op->info.end;
470 rv = 0;
471 }
472
473 dlm_release_plock_op(op);
474 out:
475 dlm_put_lockspace(ls);
476 return rv;
477 }
478 EXPORT_SYMBOL_GPL(dlm_posix_get);
479
480 /* a read copies out one plock request from the send list */
481 static ssize_t dev_read(struct file *file, char __user *u, size_t count,
482 loff_t *ppos)
483 {
484 struct dlm_plock_info info;
485 struct plock_op *op = NULL;
486
487 if (count < sizeof(info))
488 return -EINVAL;
489
490 spin_lock(&ops_lock);
491 if (!list_empty(&send_list)) {
492 op = list_first_entry(&send_list, struct plock_op, list);
493 if (op->info.flags & DLM_PLOCK_FL_CLOSE)
494 list_del(&op->list);
495 else
496 list_move_tail(&op->list, &recv_list);
497 memcpy(&info, &op->info, sizeof(info));
498 }
499 spin_unlock(&ops_lock);
500
501 if (!op)
502 return -EAGAIN;
503
504 trace_dlm_plock_read(&info);
505
506 /* there is no need to get a reply from userspace for unlocks
507 that were generated by the vfs cleaning up for a close
508 (the process did not make an unlock call). */
509
510 if (op->info.flags & DLM_PLOCK_FL_CLOSE)
511 dlm_release_plock_op(op);
512
513 if (copy_to_user(u, &info, sizeof(info)))
514 return -EFAULT;
515 return sizeof(info);
516 }
517
518 /* a write copies in one plock result that should match a plock_op
519 on the recv list */
520 static ssize_t dev_write(struct file *file, const char __user *u, size_t count,
521 loff_t *ppos)
522 {
523 struct plock_op *op = NULL, *iter;
524 struct dlm_plock_info info;
525 int do_callback = 0;
526
527 if (count != sizeof(info))
528 return -EINVAL;
529
530 if (copy_from_user(&info, u, sizeof(info)))
531 return -EFAULT;
532
533 trace_dlm_plock_write(&info);
534
535 if (check_version(&info))
536 return -EINVAL;
537
538 /*
539 * The results for waiting ops (SETLKW) can be returned in any
540 * order, so match all fields to find the op. The results for
541 * non-waiting ops are returned in the order that they were sent
542 * to userspace, so match the result with the first non-waiting op.
543 */
544 spin_lock(&ops_lock);
545 if (info.wait) {
546 op = plock_lookup_waiter(&info);
547 } else {
548 list_for_each_entry(iter, &recv_list, list) {
549 if (!iter->info.wait &&
550 iter->info.fsid == info.fsid) {
551 op = iter;
552 break;
553 }
554 }
555 }
556
557 if (op) {
558 /* Sanity check that op and info match. */
559 if (info.wait)
560 WARN_ON(op->info.optype != DLM_PLOCK_OP_LOCK);
561 else
562 WARN_ON(op->info.number != info.number ||
563 op->info.owner != info.owner ||
564 op->info.optype != info.optype);
565
566 list_del_init(&op->list);
567 memcpy(&op->info, &info, sizeof(info));
568 if (op->data)
569 do_callback = 1;
570 else
571 op->done = 1;
572 }
573 spin_unlock(&ops_lock);
574
575 if (op) {
576 if (do_callback)
577 dlm_plock_callback(op);
578 else
579 wake_up(&recv_wq);
580 } else
581 pr_debug("%s: no op %x %llx", __func__,
582 info.fsid, (unsigned long long)info.number);
583 return count;
584 }
585
586 static __poll_t dev_poll(struct file *file, poll_table *wait)
587 {
588 __poll_t mask = 0;
589
590 poll_wait(file, &send_wq, wait);
591
592 spin_lock(&ops_lock);
593 if (!list_empty(&send_list))
594 mask = EPOLLIN | EPOLLRDNORM;
595 spin_unlock(&ops_lock);
596
597 return mask;
598 }
599
600 static const struct file_operations dev_fops = {
601 .read = dev_read,
602 .write = dev_write,
603 .poll = dev_poll,
604 .owner = THIS_MODULE,
605 .llseek = noop_llseek,
606 };
607
608 static struct miscdevice plock_dev_misc = {
609 .minor = MISC_DYNAMIC_MINOR,
610 .name = DLM_PLOCK_MISC_NAME,
611 .fops = &dev_fops
612 };
613
614 int dlm_plock_init(void)
615 {
616 int rv;
617
618 rv = misc_register(&plock_dev_misc);
619 if (rv)
620 log_print("dlm_plock_init: misc_register failed %d", rv);
621 return rv;
622 }
623
624 void dlm_plock_exit(void)
625 {
626 misc_deregister(&plock_dev_misc);
627 WARN_ON(!list_empty(&send_list));
628 WARN_ON(!list_empty(&recv_list));
629 }
630
631
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