summaryrefslogtreecommitdiff
path: root/fs/ceph/locks.c
blob: ebf4ac0055ddc59815e4121550b09ebec08f801b (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
513
514
515
516
517
518
519
520
521
// SPDX-License-Identifier: GPL-2.0
#include <linux/ceph/ceph_debug.h>

#include <linux/file.h>
#include <linux/namei.h>
#include <linux/random.h>

#include "super.h"
#include "mds_client.h"
#include <linux/filelock.h>
#include <linux/ceph/pagelist.h>

static u64 lock_secret;
static int ceph_lock_wait_for_completion(struct ceph_mds_client *mdsc,
                                         struct ceph_mds_request *req);

static inline u64 secure_addr(void *addr)
{
	u64 v = lock_secret ^ (u64)(unsigned long)addr;
	/*
	 * Set the most significant bit, so that MDS knows the 'owner'
	 * is sufficient to identify the owner of lock. (old code uses
	 * both 'owner' and 'pid')
	 */
	v |= (1ULL << 63);
	return v;
}

void __init ceph_flock_init(void)
{
	get_random_bytes(&lock_secret, sizeof(lock_secret));
}

static void ceph_fl_copy_lock(struct file_lock *dst, struct file_lock *src)
{
	struct inode *inode = file_inode(dst->c.flc_file);
	atomic_inc(&ceph_inode(inode)->i_filelock_ref);
	dst->fl_u.ceph.inode = igrab(inode);
}

/*
 * Do not use the 'fl->fl_file' in release function, which
 * is possibly already released by another thread.
 */
static void ceph_fl_release_lock(struct file_lock *fl)
{
	struct inode *inode = fl->fl_u.ceph.inode;
	struct ceph_inode_info *ci;

	/*
	 * If inode is NULL it should be a request file_lock,
	 * nothing we can do.
	 */
	if (!inode)
		return;

	ci = ceph_inode(inode);
	if (atomic_dec_and_test(&ci->i_filelock_ref)) {
		/* clear error when all locks are released */
		spin_lock(&ci->i_ceph_lock);
		ci->i_ceph_flags &= ~CEPH_I_ERROR_FILELOCK;
		spin_unlock(&ci->i_ceph_lock);
	}
	fl->fl_u.ceph.inode = NULL;
	iput(inode);
}

static const struct file_lock_operations ceph_fl_lock_ops = {
	.fl_copy_lock = ceph_fl_copy_lock,
	.fl_release_private = ceph_fl_release_lock,
};

/*
 * Implement fcntl and flock locking functions.
 */
static int ceph_lock_message(u8 lock_type, u16 operation, struct inode *inode,
			     int cmd, u8 wait, struct file_lock *fl)
{
	struct ceph_mds_client *mdsc = ceph_sb_to_mdsc(inode->i_sb);
	struct ceph_client *cl = mdsc->fsc->client;
	struct ceph_mds_request *req;
	int err;
	u64 length = 0;
	u64 owner;

	if (operation == CEPH_MDS_OP_SETFILELOCK) {
		/*
		 * increasing i_filelock_ref closes race window between
		 * handling request reply and adding file_lock struct to
		 * inode. Otherwise, auth caps may get trimmed in the
		 * window. Caller function will decrease the counter.
		 */
		fl->fl_ops = &ceph_fl_lock_ops;
		fl->fl_ops->fl_copy_lock(fl, NULL);
	}

	if (operation != CEPH_MDS_OP_SETFILELOCK || cmd == CEPH_LOCK_UNLOCK)
		wait = 0;

	req = ceph_mdsc_create_request(mdsc, operation, USE_AUTH_MDS);
	if (IS_ERR(req))
		return PTR_ERR(req);
	req->r_inode = inode;
	ihold(inode);
	req->r_num_caps = 1;

	/* mds requires start and length rather than start and end */
	if (LLONG_MAX == fl->fl_end)
		length = 0;
	else
		length = fl->fl_end - fl->fl_start + 1;

	owner = secure_addr(fl->c.flc_owner);

	doutc(cl, "rule: %d, op: %d, owner: %llx, pid: %llu, "
		    "start: %llu, length: %llu, wait: %d, type: %d\n",
		    (int)lock_type, (int)operation, owner,
		    (u64) fl->c.flc_pid,
		    fl->fl_start, length, wait, fl->c.flc_type);

	req->r_args.filelock_change.rule = lock_type;
	req->r_args.filelock_change.type = cmd;
	req->r_args.filelock_change.owner = cpu_to_le64(owner);
	req->r_args.filelock_change.pid = cpu_to_le64((u64) fl->c.flc_pid);
	req->r_args.filelock_change.start = cpu_to_le64(fl->fl_start);
	req->r_args.filelock_change.length = cpu_to_le64(length);
	req->r_args.filelock_change.wait = wait;

	err = ceph_mdsc_submit_request(mdsc, inode, req);
	if (!err)
		err = ceph_mdsc_wait_request(mdsc, req, wait ?
					ceph_lock_wait_for_completion : NULL);
	if (!err && operation == CEPH_MDS_OP_GETFILELOCK) {
		fl->c.flc_pid = -le64_to_cpu(req->r_reply_info.filelock_reply->pid);
		if (CEPH_LOCK_SHARED == req->r_reply_info.filelock_reply->type)
			fl->c.flc_type = F_RDLCK;
		else if (CEPH_LOCK_EXCL == req->r_reply_info.filelock_reply->type)
			fl->c.flc_type = F_WRLCK;
		else
			fl->c.flc_type = F_UNLCK;

		fl->fl_start = le64_to_cpu(req->r_reply_info.filelock_reply->start);
		length = le64_to_cpu(req->r_reply_info.filelock_reply->start) +
						 le64_to_cpu(req->r_reply_info.filelock_reply->length);
		if (length >= 1)
			fl->fl_end = length -1;
		else
			fl->fl_end = 0;

	}
	ceph_mdsc_put_request(req);
	doutc(cl, "rule: %d, op: %d, pid: %llu, start: %llu, "
	      "length: %llu, wait: %d, type: %d, err code %d\n",
	      (int)lock_type, (int)operation, (u64) fl->c.flc_pid,
	      fl->fl_start, length, wait, fl->c.flc_type, err);
	return err;
}

static int ceph_lock_wait_for_completion(struct ceph_mds_client *mdsc,
                                         struct ceph_mds_request *req)
{
	struct ceph_client *cl = mdsc->fsc->client;
	struct ceph_mds_request *intr_req;
	struct inode *inode = req->r_inode;
	int err, lock_type;

	BUG_ON(req->r_op != CEPH_MDS_OP_SETFILELOCK);
	if (req->r_args.filelock_change.rule == CEPH_LOCK_FCNTL)
		lock_type = CEPH_LOCK_FCNTL_INTR;
	else if (req->r_args.filelock_change.rule == CEPH_LOCK_FLOCK)
		lock_type = CEPH_LOCK_FLOCK_INTR;
	else
		BUG_ON(1);
	BUG_ON(req->r_args.filelock_change.type == CEPH_LOCK_UNLOCK);

	err = wait_for_completion_interruptible(&req->r_completion);
	if (!err)
		return 0;

	doutc(cl, "request %llu was interrupted\n", req->r_tid);

	mutex_lock(&mdsc->mutex);
	if (test_bit(CEPH_MDS_R_GOT_RESULT, &req->r_req_flags)) {
		err = 0;
	} else {
		/*
		 * ensure we aren't running concurrently with
		 * ceph_fill_trace or ceph_readdir_prepopulate, which
		 * rely on locks (dir mutex) held by our caller.
		 */
		mutex_lock(&req->r_fill_mutex);
		req->r_err = err;
		set_bit(CEPH_MDS_R_ABORTED, &req->r_req_flags);
		mutex_unlock(&req->r_fill_mutex);

		if (!req->r_session) {
			// haven't sent the request
			err = 0;
		}
	}
	mutex_unlock(&mdsc->mutex);
	if (!err)
		return 0;

	intr_req = ceph_mdsc_create_request(mdsc, CEPH_MDS_OP_SETFILELOCK,
					    USE_AUTH_MDS);
	if (IS_ERR(intr_req))
		return PTR_ERR(intr_req);

	intr_req->r_inode = inode;
	ihold(inode);
	intr_req->r_num_caps = 1;

	intr_req->r_args.filelock_change = req->r_args.filelock_change;
	intr_req->r_args.filelock_change.rule = lock_type;
	intr_req->r_args.filelock_change.type = CEPH_LOCK_UNLOCK;

	err = ceph_mdsc_do_request(mdsc, inode, intr_req);
	ceph_mdsc_put_request(intr_req);

	if (err && err != -ERESTARTSYS)
		return err;

	wait_for_completion_killable(&req->r_safe_completion);
	return 0;
}

static int try_unlock_file(struct file *file, struct file_lock *fl)
{
	int err;
	unsigned int orig_flags = fl->c.flc_flags;
	fl->c.flc_flags |= FL_EXISTS;
	err = locks_lock_file_wait(file, fl);
	fl->c.flc_flags = orig_flags;
	if (err == -ENOENT) {
		if (!(orig_flags & FL_EXISTS))
			err = 0;
		return err;
	}
	return 1;
}

/*
 * Attempt to set an fcntl lock.
 * For now, this just goes away to the server. Later it may be more awesome.
 */
int ceph_lock(struct file *file, int cmd, struct file_lock *fl)
{
	struct inode *inode = file_inode(file);
	struct ceph_inode_info *ci = ceph_inode(inode);
	struct ceph_client *cl = ceph_inode_to_client(inode);
	int err = 0;
	u16 op = CEPH_MDS_OP_SETFILELOCK;
	u8 wait = 0;
	u8 lock_cmd;

	if (!(fl->c.flc_flags & FL_POSIX))
		return -ENOLCK;

	if (ceph_inode_is_shutdown(inode))
		return -ESTALE;

	doutc(cl, "fl_owner: %p\n", fl->c.flc_owner);

	/* set wait bit as appropriate, then make command as Ceph expects it*/
	if (IS_GETLK(cmd))
		op = CEPH_MDS_OP_GETFILELOCK;
	else if (IS_SETLKW(cmd))
		wait = 1;

	spin_lock(&ci->i_ceph_lock);
	if (ci->i_ceph_flags & CEPH_I_ERROR_FILELOCK) {
		err = -EIO;
	}
	spin_unlock(&ci->i_ceph_lock);
	if (err < 0) {
		if (op == CEPH_MDS_OP_SETFILELOCK && lock_is_unlock(fl))
			posix_lock_file(file, fl, NULL);
		return err;
	}

	if (lock_is_read(fl))
		lock_cmd = CEPH_LOCK_SHARED;
	else if (lock_is_write(fl))
		lock_cmd = CEPH_LOCK_EXCL;
	else
		lock_cmd = CEPH_LOCK_UNLOCK;

	if (op == CEPH_MDS_OP_SETFILELOCK && lock_is_unlock(fl)) {
		err = try_unlock_file(file, fl);
		if (err <= 0)
			return err;
	}

	err = ceph_lock_message(CEPH_LOCK_FCNTL, op, inode, lock_cmd, wait, fl);
	if (!err) {
		if (op == CEPH_MDS_OP_SETFILELOCK && F_UNLCK != fl->c.flc_type) {
			doutc(cl, "locking locally\n");
			err = posix_lock_file(file, fl, NULL);
			if (err) {
				/* undo! This should only happen if
				 * the kernel detects local
				 * deadlock. */
				ceph_lock_message(CEPH_LOCK_FCNTL, op, inode,
						  CEPH_LOCK_UNLOCK, 0, fl);
				doutc(cl, "got %d on posix_lock_file, undid lock\n",
				      err);
			}
		}
	}
	return err;
}

int ceph_flock(struct file *file, int cmd, struct file_lock *fl)
{
	struct inode *inode = file_inode(file);
	struct ceph_inode_info *ci = ceph_inode(inode);
	struct ceph_client *cl = ceph_inode_to_client(inode);
	int err = 0;
	u8 wait = 0;
	u8 lock_cmd;

	if (!(fl->c.flc_flags & FL_FLOCK))
		return -ENOLCK;

	if (ceph_inode_is_shutdown(inode))
		return -ESTALE;

	doutc(cl, "fl_file: %p\n", fl->c.flc_file);

	spin_lock(&ci->i_ceph_lock);
	if (ci->i_ceph_flags & CEPH_I_ERROR_FILELOCK) {
		err = -EIO;
	}
	spin_unlock(&ci->i_ceph_lock);
	if (err < 0) {
		if (lock_is_unlock(fl))
			locks_lock_file_wait(file, fl);
		return err;
	}

	if (IS_SETLKW(cmd))
		wait = 1;

	if (lock_is_read(fl))
		lock_cmd = CEPH_LOCK_SHARED;
	else if (lock_is_write(fl))
		lock_cmd = CEPH_LOCK_EXCL;
	else
		lock_cmd = CEPH_LOCK_UNLOCK;

	if (lock_is_unlock(fl)) {
		err = try_unlock_file(file, fl);
		if (err <= 0)
			return err;
	}

	err = ceph_lock_message(CEPH_LOCK_FLOCK, CEPH_MDS_OP_SETFILELOCK,
				inode, lock_cmd, wait, fl);
	if (!err && F_UNLCK != fl->c.flc_type) {
		err = locks_lock_file_wait(file, fl);
		if (err) {
			ceph_lock_message(CEPH_LOCK_FLOCK,
					  CEPH_MDS_OP_SETFILELOCK,
					  inode, CEPH_LOCK_UNLOCK, 0, fl);
			doutc(cl, "got %d on locks_lock_file_wait, undid lock\n",
			      err);
		}
	}
	return err;
}

/*
 * Fills in the passed counter variables, so you can prepare pagelist metadata
 * before calling ceph_encode_locks.
 */
void ceph_count_locks(struct inode *inode, int *fcntl_count, int *flock_count)
{
	struct ceph_client *cl = ceph_inode_to_client(inode);
	struct file_lock *lock;
	struct file_lock_context *ctx;

	*fcntl_count = 0;
	*flock_count = 0;

	ctx = locks_inode_context(inode);
	if (ctx) {
		spin_lock(&ctx->flc_lock);
		for_each_file_lock(lock, &ctx->flc_posix)
			++(*fcntl_count);
		for_each_file_lock(lock, &ctx->flc_flock)
			++(*flock_count);
		spin_unlock(&ctx->flc_lock);
	}
	doutc(cl, "counted %d flock locks and %d fcntl locks\n",
	      *flock_count, *fcntl_count);
}

/*
 * Given a pointer to a lock, convert it to a ceph filelock
 */
static int lock_to_ceph_filelock(struct inode *inode,
				 struct file_lock *lock,
				 struct ceph_filelock *cephlock)
{
	struct ceph_client *cl = ceph_inode_to_client(inode);
	int err = 0;

	cephlock->start = cpu_to_le64(lock->fl_start);
	cephlock->length = cpu_to_le64(lock->fl_end - lock->fl_start + 1);
	cephlock->client = cpu_to_le64(0);
	cephlock->pid = cpu_to_le64((u64) lock->c.flc_pid);
	cephlock->owner = cpu_to_le64(secure_addr(lock->c.flc_owner));

	switch (lock->c.flc_type) {
	case F_RDLCK:
		cephlock->type = CEPH_LOCK_SHARED;
		break;
	case F_WRLCK:
		cephlock->type = CEPH_LOCK_EXCL;
		break;
	case F_UNLCK:
		cephlock->type = CEPH_LOCK_UNLOCK;
		break;
	default:
		doutc(cl, "Have unknown lock type %d\n",
		      lock->c.flc_type);
		err = -EINVAL;
	}

	return err;
}

/*
 * Encode the flock and fcntl locks for the given inode into the ceph_filelock
 * array. Must be called with inode->i_lock already held.
 * If we encounter more of a specific lock type than expected, return -ENOSPC.
 */
int ceph_encode_locks_to_buffer(struct inode *inode,
				struct ceph_filelock *flocks,
				int num_fcntl_locks, int num_flock_locks)
{
	struct file_lock *lock;
	struct file_lock_context *ctx = locks_inode_context(inode);
	struct ceph_client *cl = ceph_inode_to_client(inode);
	int err = 0;
	int seen_fcntl = 0;
	int seen_flock = 0;
	int l = 0;

	doutc(cl, "encoding %d flock and %d fcntl locks\n", num_flock_locks,
	      num_fcntl_locks);

	if (!ctx)
		return 0;

	spin_lock(&ctx->flc_lock);
	for_each_file_lock(lock, &ctx->flc_posix) {
		++seen_fcntl;
		if (seen_fcntl > num_fcntl_locks) {
			err = -ENOSPC;
			goto fail;
		}
		err = lock_to_ceph_filelock(inode, lock, &flocks[l]);
		if (err)
			goto fail;
		++l;
	}
	for_each_file_lock(lock, &ctx->flc_flock) {
		++seen_flock;
		if (seen_flock > num_flock_locks) {
			err = -ENOSPC;
			goto fail;
		}
		err = lock_to_ceph_filelock(inode, lock, &flocks[l]);
		if (err)
			goto fail;
		++l;
	}
fail:
	spin_unlock(&ctx->flc_lock);
	return err;
}

/*
 * Copy the encoded flock and fcntl locks into the pagelist.
 * Format is: #fcntl locks, sequential fcntl locks, #flock locks,
 * sequential flock locks.
 * Returns zero on success.
 */
int ceph_locks_to_pagelist(struct ceph_filelock *flocks,
			   struct ceph_pagelist *pagelist,
			   int num_fcntl_locks, int num_flock_locks)
{
	int err = 0;
	__le32 nlocks;

	nlocks = cpu_to_le32(num_fcntl_locks);
	err = ceph_pagelist_append(pagelist, &nlocks, sizeof(nlocks));
	if (err)
		goto out_fail;

	if (num_fcntl_locks > 0) {
		err = ceph_pagelist_append(pagelist, flocks,
					   num_fcntl_locks * sizeof(*flocks));
		if (err)
			goto out_fail;
	}

	nlocks = cpu_to_le32(num_flock_locks);
	err = ceph_pagelist_append(pagelist, &nlocks, sizeof(nlocks));
	if (err)
		goto out_fail;

	if (num_flock_locks > 0) {
		err = ceph_pagelist_append(pagelist, &flocks[num_fcntl_locks],
					   num_flock_locks * sizeof(*flocks));
	}
out_fail:
	return err;
}