aboutsummaryrefslogtreecommitdiff
path: root/fs/dlm/plock.c
blob: 737f185aad8dd1c8b82271c3819a7de319194cc3 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2005-2008 Red Hat, Inc.  All rights reserved.
 */

#include <linux/fs.h>
#include <linux/miscdevice.h>
#include <linux/poll.h>
#include <linux/dlm.h>
#include <linux/dlm_plock.h>
#include <linux/slab.h>

#include "dlm_internal.h"
#include "lockspace.h"

static DEFINE_SPINLOCK(ops_lock);
static LIST_HEAD(send_list);
static LIST_HEAD(recv_list);
static DECLARE_WAIT_QUEUE_HEAD(send_wq);
static DECLARE_WAIT_QUEUE_HEAD(recv_wq);

struct plock_async_data {
	void *fl;
	void *file;
	struct file_lock flc;
	int (*callback)(struct file_lock *fl, int result);
};

struct plock_op {
	struct list_head list;
	int done;
	/* if lock op got interrupted while waiting dlm_controld reply */
	bool sigint;
	struct dlm_plock_info info;
	/* if set indicates async handling */
	struct plock_async_data *data;
};

static inline void set_version(struct dlm_plock_info *info)
{
	info->version[0] = DLM_PLOCK_VERSION_MAJOR;
	info->version[1] = DLM_PLOCK_VERSION_MINOR;
	info->version[2] = DLM_PLOCK_VERSION_PATCH;
}

static int check_version(struct dlm_plock_info *info)
{
	if ((DLM_PLOCK_VERSION_MAJOR != info->version[0]) ||
	    (DLM_PLOCK_VERSION_MINOR < info->version[1])) {
		log_print("plock device version mismatch: "
			  "kernel (%u.%u.%u), user (%u.%u.%u)",
			  DLM_PLOCK_VERSION_MAJOR,
			  DLM_PLOCK_VERSION_MINOR,
			  DLM_PLOCK_VERSION_PATCH,
			  info->version[0],
			  info->version[1],
			  info->version[2]);
		return -EINVAL;
	}
	return 0;
}

static void dlm_release_plock_op(struct plock_op *op)
{
	kfree(op->data);
	kfree(op);
}

static void send_op(struct plock_op *op)
{
	set_version(&op->info);
	spin_lock(&ops_lock);
	list_add_tail(&op->list, &send_list);
	spin_unlock(&ops_lock);
	wake_up(&send_wq);
}

/* If a process was killed while waiting for the only plock on a file,
   locks_remove_posix will not see any lock on the file so it won't
   send an unlock-close to us to pass on to userspace to clean up the
   abandoned waiter.  So, we have to insert the unlock-close when the
   lock call is interrupted. */

static void do_unlock_close(const struct dlm_plock_info *info)
{
	struct plock_op *op;

	op = kzalloc(sizeof(*op), GFP_NOFS);
	if (!op)
		return;

	op->info.optype		= DLM_PLOCK_OP_UNLOCK;
	op->info.pid		= info->pid;
	op->info.fsid		= info->fsid;
	op->info.number		= info->number;
	op->info.start		= 0;
	op->info.end		= OFFSET_MAX;
	op->info.owner		= info->owner;

	op->info.flags |= DLM_PLOCK_FL_CLOSE;
	send_op(op);
}

int dlm_posix_lock(dlm_lockspace_t *lockspace, u64 number, struct file *file,
		   int cmd, struct file_lock *fl)
{
	struct plock_async_data *op_data;
	struct dlm_ls *ls;
	struct plock_op *op;
	int rv;

	ls = dlm_find_lockspace_local(lockspace);
	if (!ls)
		return -EINVAL;

	op = kzalloc(sizeof(*op), GFP_NOFS);
	if (!op) {
		rv = -ENOMEM;
		goto out;
	}

	op->info.optype		= DLM_PLOCK_OP_LOCK;
	op->info.pid		= fl->fl_pid;
	op->info.ex		= (fl->fl_type == F_WRLCK);
	op->info.wait		= IS_SETLKW(cmd);
	op->info.fsid		= ls->ls_global_id;
	op->info.number		= number;
	op->info.start		= fl->fl_start;
	op->info.end		= fl->fl_end;
	/* async handling */
	if (fl->fl_lmops && fl->fl_lmops->lm_grant) {
		op_data = kzalloc(sizeof(*op_data), GFP_NOFS);
		if (!op_data) {
			dlm_release_plock_op(op);
			rv = -ENOMEM;
			goto out;
		}

		/* fl_owner is lockd which doesn't distinguish
		   processes on the nfs client */
		op->info.owner	= (__u64) fl->fl_pid;
		op_data->callback = fl->fl_lmops->lm_grant;
		locks_init_lock(&op_data->flc);
		locks_copy_lock(&op_data->flc, fl);
		op_data->fl		= fl;
		op_data->file	= file;

		op->data = op_data;

		send_op(op);
		rv = FILE_LOCK_DEFERRED;
		goto out;
	} else {
		op->info.owner	= (__u64)(long) fl->fl_owner;
	}

	send_op(op);

	rv = wait_event_interruptible(recv_wq, (op->done != 0));
	if (rv == -ERESTARTSYS) {
		spin_lock(&ops_lock);
		/* recheck under ops_lock if we got a done != 0,
		 * if so this interrupt case should be ignored
		 */
		if (op->done != 0) {
			spin_unlock(&ops_lock);
			goto do_lock_wait;
		}

		op->sigint = true;
		spin_unlock(&ops_lock);
		log_debug(ls, "%s: wait interrupted %x %llx pid %d",
			  __func__, ls->ls_global_id,
			  (unsigned long long)number, op->info.pid);
		goto out;
	}

do_lock_wait:

	WARN_ON(!list_empty(&op->list));

	rv = op->info.rv;

	if (!rv) {
		if (locks_lock_file_wait(file, fl) < 0)
			log_error(ls, "dlm_posix_lock: vfs lock error %llx",
				  (unsigned long long)number);
	}

	dlm_release_plock_op(op);
out:
	dlm_put_lockspace(ls);
	return rv;
}
EXPORT_SYMBOL_GPL(dlm_posix_lock);

/* Returns failure iff a successful lock operation should be canceled */
static int dlm_plock_callback(struct plock_op *op)
{
	struct plock_async_data *op_data = op->data;
	struct file *file;
	struct file_lock *fl;
	struct file_lock *flc;
	int (*notify)(struct file_lock *fl, int result) = NULL;
	int rv = 0;

	WARN_ON(!list_empty(&op->list));

	/* check if the following 2 are still valid or make a copy */
	file = op_data->file;
	flc = &op_data->flc;
	fl = op_data->fl;
	notify = op_data->callback;

	if (op->info.rv) {
		notify(fl, op->info.rv);
		goto out;
	}

	/* got fs lock; bookkeep locally as well: */
	flc->fl_flags &= ~FL_SLEEP;
	if (posix_lock_file(file, flc, NULL)) {
		/*
		 * This can only happen in the case of kmalloc() failure.
		 * The filesystem's own lock is the authoritative lock,
		 * so a failure to get the lock locally is not a disaster.
		 * As long as the fs cannot reliably cancel locks (especially
		 * in a low-memory situation), we're better off ignoring
		 * this failure than trying to recover.
		 */
		log_print("dlm_plock_callback: vfs lock error %llx file %p fl %p",
			  (unsigned long long)op->info.number, file, fl);
	}

	rv = notify(fl, 0);
	if (rv) {
		/* XXX: We need to cancel the fs lock here: */
		log_print("dlm_plock_callback: lock granted after lock request "
			  "failed; dangling lock!\n");
		goto out;
	}

out:
	dlm_release_plock_op(op);
	return rv;
}

int dlm_posix_unlock(dlm_lockspace_t *lockspace, u64 number, struct file *file,
		     struct file_lock *fl)
{
	struct dlm_ls *ls;
	struct plock_op *op;
	int rv;
	unsigned char fl_flags = fl->fl_flags;

	ls = dlm_find_lockspace_local(lockspace);
	if (!ls)
		return -EINVAL;

	op = kzalloc(sizeof(*op), GFP_NOFS);
	if (!op) {
		rv = -ENOMEM;
		goto out;
	}

	/* cause the vfs unlock to return ENOENT if lock is not found */
	fl->fl_flags |= FL_EXISTS;

	rv = locks_lock_file_wait(file, fl);
	if (rv == -ENOENT) {
		rv = 0;
		goto out_free;
	}
	if (rv < 0) {
		log_error(ls, "dlm_posix_unlock: vfs unlock error %d %llx",
			  rv, (unsigned long long)number);
	}

	op->info.optype		= DLM_PLOCK_OP_UNLOCK;
	op->info.pid		= fl->fl_pid;
	op->info.fsid		= ls->ls_global_id;
	op->info.number		= number;
	op->info.start		= fl->fl_start;
	op->info.end		= fl->fl_end;
	if (fl->fl_lmops && fl->fl_lmops->lm_grant)
		op->info.owner	= (__u64) fl->fl_pid;
	else
		op->info.owner	= (__u64)(long) fl->fl_owner;

	if (fl->fl_flags & FL_CLOSE) {
		op->info.flags |= DLM_PLOCK_FL_CLOSE;
		send_op(op);
		rv = 0;
		goto out;
	}

	send_op(op);
	wait_event(recv_wq, (op->done != 0));

	WARN_ON(!list_empty(&op->list));

	rv = op->info.rv;

	if (rv == -ENOENT)
		rv = 0;

out_free:
	dlm_release_plock_op(op);
out:
	dlm_put_lockspace(ls);
	fl->fl_flags = fl_flags;
	return rv;
}
EXPORT_SYMBOL_GPL(dlm_posix_unlock);

int dlm_posix_get(dlm_lockspace_t *lockspace, u64 number, struct file *file,
		  struct file_lock *fl)
{
	struct dlm_ls *ls;
	struct plock_op *op;
	int rv;

	ls = dlm_find_lockspace_local(lockspace);
	if (!ls)
		return -EINVAL;

	op = kzalloc(sizeof(*op), GFP_NOFS);
	if (!op) {
		rv = -ENOMEM;
		goto out;
	}

	op->info.optype		= DLM_PLOCK_OP_GET;
	op->info.pid		= fl->fl_pid;
	op->info.ex		= (fl->fl_type == F_WRLCK);
	op->info.fsid		= ls->ls_global_id;
	op->info.number		= number;
	op->info.start		= fl->fl_start;
	op->info.end		= fl->fl_end;
	if (fl->fl_lmops && fl->fl_lmops->lm_grant)
		op->info.owner	= (__u64) fl->fl_pid;
	else
		op->info.owner	= (__u64)(long) fl->fl_owner;

	send_op(op);
	wait_event(recv_wq, (op->done != 0));

	WARN_ON(!list_empty(&op->list));

	/* info.rv from userspace is 1 for conflict, 0 for no-conflict,
	   -ENOENT if there are no locks on the file */

	rv = op->info.rv;

	fl->fl_type = F_UNLCK;
	if (rv == -ENOENT)
		rv = 0;
	else if (rv > 0) {
		locks_init_lock(fl);
		fl->fl_type = (op->info.ex) ? F_WRLCK : F_RDLCK;
		fl->fl_flags = FL_POSIX;
		fl->fl_pid = -op->info.pid;
		fl->fl_start = op->info.start;
		fl->fl_end = op->info.end;
		rv = 0;
	}

	dlm_release_plock_op(op);
out:
	dlm_put_lockspace(ls);
	return rv;
}
EXPORT_SYMBOL_GPL(dlm_posix_get);

/* a read copies out one plock request from the send list */
static ssize_t dev_read(struct file *file, char __user *u, size_t count,
			loff_t *ppos)
{
	struct dlm_plock_info info;
	struct plock_op *op = NULL;

	if (count < sizeof(info))
		return -EINVAL;

	spin_lock(&ops_lock);
	if (!list_empty(&send_list)) {
		op = list_first_entry(&send_list, struct plock_op, list);
		if (op->info.flags & DLM_PLOCK_FL_CLOSE)
			list_del(&op->list);
		else
			list_move(&op->list, &recv_list);
		memcpy(&info, &op->info, sizeof(info));
	}
	spin_unlock(&ops_lock);

	if (!op)
		return -EAGAIN;

	/* there is no need to get a reply from userspace for unlocks
	   that were generated by the vfs cleaning up for a close
	   (the process did not make an unlock call). */

	if (op->info.flags & DLM_PLOCK_FL_CLOSE)
		dlm_release_plock_op(op);

	if (copy_to_user(u, &info, sizeof(info)))
		return -EFAULT;
	return sizeof(info);
}

/* a write copies in one plock result that should match a plock_op
   on the recv list */
static ssize_t dev_write(struct file *file, const char __user *u, size_t count,
			 loff_t *ppos)
{
	struct plock_op *op = NULL, *iter;
	struct dlm_plock_info info;
	int do_callback = 0;

	if (count != sizeof(info))
		return -EINVAL;

	if (copy_from_user(&info, u, sizeof(info)))
		return -EFAULT;

	if (check_version(&info))
		return -EINVAL;

	spin_lock(&ops_lock);
	list_for_each_entry(iter, &recv_list, list) {
		if (iter->info.fsid == info.fsid &&
		    iter->info.number == info.number &&
		    iter->info.owner == info.owner) {
			if (iter->sigint) {
				list_del(&iter->list);
				spin_unlock(&ops_lock);

				pr_debug("%s: sigint cleanup %x %llx pid %d",
					  __func__, iter->info.fsid,
					  (unsigned long long)iter->info.number,
					  iter->info.pid);
				do_unlock_close(&iter->info);
				memcpy(&iter->info, &info, sizeof(info));
				dlm_release_plock_op(iter);
				return count;
			}
			list_del_init(&iter->list);
			memcpy(&iter->info, &info, sizeof(info));
			if (iter->data)
				do_callback = 1;
			else
				iter->done = 1;
			op = iter;
			break;
		}
	}
	spin_unlock(&ops_lock);

	if (op) {
		if (do_callback)
			dlm_plock_callback(op);
		else
			wake_up(&recv_wq);
	} else
		log_print("%s: no op %x %llx", __func__,
			  info.fsid, (unsigned long long)info.number);
	return count;
}

static __poll_t dev_poll(struct file *file, poll_table *wait)
{
	__poll_t mask = 0;

	poll_wait(file, &send_wq, wait);

	spin_lock(&ops_lock);
	if (!list_empty(&send_list))
		mask = EPOLLIN | EPOLLRDNORM;
	spin_unlock(&ops_lock);

	return mask;
}

static const struct file_operations dev_fops = {
	.read    = dev_read,
	.write   = dev_write,
	.poll    = dev_poll,
	.owner   = THIS_MODULE,
	.llseek  = noop_llseek,
};

static struct miscdevice plock_dev_misc = {
	.minor = MISC_DYNAMIC_MINOR,
	.name = DLM_PLOCK_MISC_NAME,
	.fops = &dev_fops
};

int dlm_plock_init(void)
{
	int rv;

	rv = misc_register(&plock_dev_misc);
	if (rv)
		log_print("dlm_plock_init: misc_register failed %d", rv);
	return rv;
}

void dlm_plock_exit(void)
{
	misc_deregister(&plock_dev_misc);
}