summaryrefslogtreecommitdiffstats
path: root/fs/quota/quota_tree.c
blob: 24f03407eeb53317f9bbdf42323f2d1649f211ce (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
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
/*
 *	vfsv0 quota IO operations on file
 */

#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/mount.h>
#include <linux/dqblk_v2.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/quotaops.h>

#include <asm/byteorder.h>

#include "quota_tree.h"

MODULE_AUTHOR("Jan Kara");
MODULE_DESCRIPTION("Quota trie support");
MODULE_LICENSE("GPL");

#define __QUOTA_QT_PARANOIA

static int get_index(struct qtree_mem_dqinfo *info, qid_t id, int depth)
{
	unsigned int epb = info->dqi_usable_bs >> 2;

	depth = info->dqi_qtree_depth - depth - 1;
	while (depth--)
		id /= epb;
	return id % epb;
}

/* Number of entries in one blocks */
static int qtree_dqstr_in_blk(struct qtree_mem_dqinfo *info)
{
	return (info->dqi_usable_bs - sizeof(struct qt_disk_dqdbheader))
	       / info->dqi_entry_size;
}

static char *getdqbuf(size_t size)
{
	char *buf = kmalloc(size, GFP_NOFS);
	if (!buf)
		printk(KERN_WARNING
		       "VFS: Not enough memory for quota buffers.\n");
	return buf;
}

static ssize_t read_blk(struct qtree_mem_dqinfo *info, uint blk, char *buf)
{
	struct super_block *sb = info->dqi_sb;

	memset(buf, 0, info->dqi_usable_bs);
	return sb->s_op->quota_read(sb, info->dqi_type, buf,
	       info->dqi_usable_bs, blk << info->dqi_blocksize_bits);
}

static ssize_t write_blk(struct qtree_mem_dqinfo *info, uint blk, char *buf)
{
	struct super_block *sb = info->dqi_sb;
	ssize_t ret;

	ret = sb->s_op->quota_write(sb, info->dqi_type, buf,
	       info->dqi_usable_bs, blk << info->dqi_blocksize_bits);
	if (ret != info->dqi_usable_bs) {
		q_warn(KERN_WARNING "VFS: dquota write failed on "
			"dev %s\n", sb->s_id);
		if (ret >= 0)
			ret = -EIO;
	}
	return ret;
}

/* Remove empty block from list and return it */
static int get_free_dqblk(struct qtree_mem_dqinfo *info)
{
	char *buf = getdqbuf(info->dqi_usable_bs);
	struct qt_disk_dqdbheader *dh = (struct qt_disk_dqdbheader *)buf;
	int ret, blk;

	if (!buf)
		return -ENOMEM;
	if (info->dqi_free_blk) {
		blk = info->dqi_free_blk;
		ret = read_blk(info, blk, buf);
		if (ret < 0)
			goto out_buf;
		info->dqi_free_blk = le32_to_cpu(dh->dqdh_next_free);
	}
	else {
		memset(buf, 0, info->dqi_usable_bs);
		/* Assure block allocation... */
		ret = write_blk(info, info->dqi_blocks, buf);
		if (ret < 0)
			goto out_buf;
		blk = info->dqi_blocks++;
	}
	mark_info_dirty(info->dqi_sb, info->dqi_type);
	ret = blk;
out_buf:
	kfree(buf);
	return ret;
}

/* Insert empty block to the list */
static int put_free_dqblk(struct qtree_mem_dqinfo *info, char *buf, uint blk)
{
	struct qt_disk_dqdbheader *dh = (struct qt_disk_dqdbheader *)buf;
	int err;

	dh->dqdh_next_free = cpu_to_le32(info->dqi_free_blk);
	dh->dqdh_prev_free = cpu_to_le32(0);
	dh->dqdh_entries = cpu_to_le16(0);
	err = write_blk(info, blk, buf);
	if (err < 0)
		return err;
	info->dqi_free_blk = blk;
	mark_info_dirty(info->dqi_sb, info->dqi_type);
	return 0;
}

/* Remove given block from the list of blocks with free entries */
static int remove_free_dqentry(struct qtree_mem_dqinfo *info, char *buf,
			       uint blk)
{
	char *tmpbuf = getdqbuf(info->dqi_usable_bs);
	struct qt_disk_dqdbheader *dh = (struct qt_disk_dqdbheader *)buf;
	uint nextblk = le32_to_cpu(dh->dqdh_next_free);
	uint prevblk = le32_to_cpu(dh->dqdh_prev_free);
	int err;

	if (!tmpbuf)
		return -ENOMEM;
	if (nextblk) {
		err = read_blk(info, nextblk, tmpbuf);
		if (err < 0)
			goto out_buf;
		((struct qt_disk_dqdbheader *)tmpbuf)->dqdh_prev_free =
							dh->dqdh_prev_free;
		err = write_blk(info, nextblk, tmpbuf);
		if (err < 0)
			goto out_buf;
	}
	if (prevblk) {
		err = read_blk(info, prevblk, tmpbuf);
		if (err < 0)
			goto out_buf;
		((struct qt_disk_dqdbheader *)tmpbuf)->dqdh_next_free =
							dh->dqdh_next_free;
		err = write_blk(info, prevblk, tmpbuf);
		if (err < 0)
			goto out_buf;
	} else {
		info->dqi_free_entry = nextblk;
		mark_info_dirty(info->dqi_sb, info->dqi_type);
	}
	kfree(tmpbuf);
	dh->dqdh_next_free = dh->dqdh_prev_free = cpu_to_le32(0);
	/* No matter whether write succeeds block is out of list */
	if (write_blk(info, blk, buf) < 0)
		q_warn(KERN_ERR
		       "VFS: Can't write block (%u) with free entries.\n",
		       blk);
	return 0;
out_buf:
	kfree(tmpbuf);
	return err;
}

/* Insert given block to the beginning of list with free entries */
static int insert_free_dqentry(struct qtree_mem_dqinfo *info, char *buf,
			       uint blk)
{
	char *tmpbuf = getdqbuf(info->dqi_usable_bs);
	struct qt_disk_dqdbheader *dh = (struct qt_disk_dqdbheader *)buf;
	int err;

	if (!tmpbuf)
		return -ENOMEM;
	dh->dqdh_next_free = cpu_to_le32(info->dqi_free_entry);
	dh->dqdh_prev_free = cpu_to_le32(0);
	err = write_blk(info, blk, buf);
	if (err < 0)
		goto out_buf;
	if (info->dqi_free_entry) {
		err = read_blk(info, info->dqi_free_entry, tmpbuf);
		if (err < 0)
			goto out_buf;
		((struct qt_disk_dqdbheader *)tmpbuf)->dqdh_prev_free =
							cpu_to_le32(blk);
		err = write_blk(info, info->dqi_free_entry, tmpbuf);
		if (err < 0)
			goto out_buf;
	}
	kfree(tmpbuf);
	info->dqi_free_entry = blk;
	mark_info_dirty(info->dqi_sb, info->dqi_type);
	return 0;
out_buf:
	kfree(tmpbuf);
	return err;
}

/* Is the entry in the block free? */
int qtree_entry_unused(struct qtree_mem_dqinfo *info, char *disk)
{
	int i;

	for (i = 0; i < info->dqi_entry_size; i++)
		if (disk[i])
			return 0;
	return 1;
}
EXPORT_SYMBOL(qtree_entry_unused);

/* Find space for dquot */
static uint find_free_dqentry(struct qtree_mem_dqinfo *info,
			      struct dquot *dquot, int *err)
{
	uint blk, i;
	struct qt_disk_dqdbheader *dh;
	char *buf = getdqbuf(info->dqi_usable_bs);
	char *ddquot;

	*err = 0;
	if (!buf) {
		*err = -ENOMEM;
		return 0;
	}
	dh = (struct qt_disk_dqdbheader *)buf;
	if (info->dqi_free_entry) {
		blk = info->dqi_free_entry;
		*err = read_blk(info, blk, buf);
		if (*err < 0)
			goto out_buf;
	} else {
		blk = get_free_dqblk(info);
		if ((int)blk < 0) {
			*err = blk;
			kfree(buf);
			return 0;
		}
		memset(buf, 0, info->dqi_usable_bs);
		/* This is enough as the block is already zeroed and the entry
		 * list is empty... */
		info->dqi_free_entry = blk;
		mark_info_dirty(dquot->dq_sb, dquot->dq_type);
	}
	/* Block will be full? */
	if (le16_to_cpu(dh->dqdh_entries) + 1 >= qtree_dqstr_in_blk(info)) {
		*err = remove_free_dqentry(info, buf, blk);
		if (*err < 0) {
			q_warn(KERN_ERR "VFS: find_free_dqentry(): Can't "
			       "remove block (%u) from entry free list.\n",
			       blk);
			goto out_buf;
		}
	}
	le16_add_cpu(&dh->dqdh_entries, 1);
	/* Find free structure in block */
	ddquot = buf + sizeof(struct qt_disk_dqdbheader);
	for (i = 0; i < qtree_dqstr_in_blk(info); i++) {
		if (qtree_entry_unused(info, ddquot))
			break;
		ddquot += info->dqi_entry_size;
	}
#ifdef __QUOTA_QT_PARANOIA
	if (i == qtree_dqstr_in_blk(info)) {
		printk(KERN_ERR "VFS: find_free_dqentry(): Data block full "
				"but it shouldn't.\n");
		*err = -EIO;
		goto out_buf;
	}
#endif
	*err = write_blk(info, blk, buf);
	if (*err < 0) {
		q_warn(KERN_ERR "VFS: find_free_dqentry(): Can't write quota "
				"data block %u.\n", blk);
		goto out_buf;
	}
	dquot->dq_off = (blk << info->dqi_blocksize_bits) +
			sizeof(struct qt_disk_dqdbheader) +
			i * info->dqi_entry_size;
	kfree(buf);
	return blk;
out_buf:
	kfree(buf);
	return 0;
}

/* Insert reference to structure into the trie */
static int do_insert_tree(struct qtree_mem_dqinfo *info, struct dquot *dquot,
			  uint *treeblk, int depth)
{
	char *buf = getdqbuf(info->dqi_usable_bs);
	int ret = 0, newson = 0, newact = 0;
	__le32 *ref;
	uint newblk;

	if (!buf)
		return -ENOMEM;
	if (!*treeblk) {
		ret = get_free_dqblk(info);
		if (ret < 0)
			goto out_buf;
		*treeblk = ret;
		memset(buf, 0, info->dqi_usable_bs);
		newact = 1;
	} else {
		ret = read_blk(info, *treeblk, buf);
		if (ret < 0) {
			q_warn(KERN_ERR "VFS: Can't read tree quota block "
					"%u.\n", *treeblk);
			goto out_buf;
		}
	}
	ref = (__le32 *)buf;
	newblk = le32_to_cpu(ref[get_index(info, dquot->dq_id, depth)]);
	if (!newblk)
		newson = 1;
	if (depth == info->dqi_qtree_depth - 1) {
#ifdef __QUOTA_QT_PARANOIA
		if (newblk) {
			printk(KERN_ERR "VFS: Inserting already present quota "
					"entry (block %u).\n",
			       le32_to_cpu(ref[get_index(info,
						dquot->dq_id, depth)]));
			ret = -EIO;
			goto out_buf;
		}
#endif
		newblk = find_free_dqentry(info, dquot, &ret);
	} else {
		ret = do_insert_tree(info, dquot, &newblk, depth+1);
	}
	if (newson && ret >= 0) {
		ref[get_index(info, dquot->dq_id, depth)] =
							cpu_to_le32(newblk);
		ret = write_blk(info, *treeblk, buf);
	} else if (newact && ret < 0) {
		put_free_dqblk(info, buf, *treeblk);
	}
out_buf:
	kfree(buf);
	return ret;
}

/* Wrapper for inserting quota structure into tree */
static inline int dq_insert_tree(struct qtree_mem_dqinfo *info,
				 struct dquot *dquot)
{
	int tmp = QT_TREEOFF;
	return do_insert_tree(info, dquot, &tmp, 0);
}

/*
 * We don't have to be afraid of deadlocks as we never have quotas on quota
 * files...
 */
int qtree_write_dquot(struct qtree_mem_dqinfo *info, struct dquot *dquot)
{
	int type = dquot->dq_type;
	struct super_block *sb = dquot->dq_sb;
	ssize_t ret;
	char *ddquot = getdqbuf(info->dqi_entry_size);

	if (!ddquot)
		return -ENOMEM;

	/* dq_off is guarded by dqio_mutex */
	if (!dquot->dq_off) {
		ret = dq_insert_tree(info, dquot);
		if (ret < 0) {
			q_warn(KERN_ERR "VFS: Error %zd occurred while "
					"creating quota.\n", ret);
			kfree(ddquot);
			return ret;
		}
	}
	spin_lock(&dq_data_lock);
	info->dqi_ops->mem2disk_dqblk(ddquot, dquot);
	spin_unlock(&dq_data_lock);
	ret = sb->s_op->quota_write(sb, type, ddquot, info->dqi_entry_size,
				    dquot->dq_off);
	if (ret != info->dqi_entry_size) {
		q_warn(KERN_WARNING "VFS: dquota write failed on dev %s\n",
		       sb->s_id);
		if (ret >= 0)
			ret = -ENOSPC;
	} else {
		ret = 0;
	}
	dqstats_inc(DQST_WRITES);
	kfree(ddquot);

	return ret;
}
EXPORT_SYMBOL(qtree_write_dquot);

/* Free dquot entry in data block */
static int free_dqentry(struct qtree_mem_dqinfo *info, struct dquot *dquot,
			uint blk)
{
	struct qt_disk_dqdbheader *dh;
	char *buf = getdqbuf(info->dqi_usable_bs);
	int ret = 0;

	if (!buf)
		return -ENOMEM;
	if (dquot->dq_off >> info->dqi_blocksize_bits != blk) {
		q_warn(KERN_ERR "VFS: Quota structure has offset to other "
		  "block (%u) than it should (%u).\n", blk,
		  (uint)(dquot->dq_off >> info->dqi_blocksize_bits));
		goto out_buf;
	}
	ret = read_blk(info, blk, buf);
	if (ret < 0) {
		q_warn(KERN_ERR "VFS: Can't read quota data block %u\n", blk);
		goto out_buf;
	}
	dh = (struct qt_disk_dqdbheader *)buf;
	le16_add_cpu(&dh->dqdh_entries, -1);
	if (!le16_to_cpu(dh->dqdh_entries)) {	/* Block got free? */
		ret = remove_free_dqentry(info, buf, blk);
		if (ret >= 0)
			ret = put_free_dqblk(info, buf, blk);
		if (ret < 0) {
			q_warn(KERN_ERR "VFS: Can't move quota data block (%u) "
			  "to free list.\n", blk);
			goto out_buf;
		}
	} else {
		memset(buf +
		       (dquot->dq_off & ((1 << info->dqi_blocksize_bits) - 1)),
		       0, info->dqi_entry_size);
		if (le16_to_cpu(dh->dqdh_entries) ==
		    qtree_dqstr_in_blk(info) - 1) {
			/* Insert will write block itself */
			ret = insert_free_dqentry(info, buf, blk);
			if (ret < 0) {
				q_warn(KERN_ERR "VFS: Can't insert quota data "
				       "block (%u) to free entry list.\n", blk);
				goto out_buf;
			}
		} else {
			ret = write_blk(info, blk, buf);
			if (ret < 0) {
				q_warn(KERN_ERR "VFS: Can't write quota data "
				  "block %u\n", blk);
				goto out_buf;
			}
		}
	}
	dquot->dq_off = 0;	/* Quota is now unattached */
out_buf:
	kfree(buf);
	return ret;
}

/* Remove reference to dquot from tree */
static int remove_tree(struct qtree_mem_dqinfo *info, struct dquot *dquot,
		       uint *blk, int depth)
{
	char *buf = getdqbuf(info->dqi_usable_bs);
	int ret = 0;
	uint newblk;
	__le32 *ref = (__le32 *)buf;

	if (!buf)
		return -ENOMEM;
	ret = read_blk(info, *blk, buf);
	if (ret < 0) {
		q_warn(KERN_ERR "VFS: Can't read quota data block %u\n", *blk);
		goto out_buf;
	}
	newblk = le32_to_cpu(ref[get_index(info, dquot->dq_id, depth)]);
	if (depth == info->dqi_qtree_depth - 1) {
		ret = free_dqentry(info, dquot, newblk);
		newblk = 0;
	} else {
		ret = remove_tree(info, dquot, &newblk, depth+1);
	}
	if (ret >= 0 && !newblk) {
		int i;
		ref[get_index(info, dquot->dq_id, depth)] = cpu_to_le32(0);
		/* Block got empty? */
		for (i = 0; i < (info->dqi_usable_bs >> 2) && !ref[i]; i++)
			;
		/* Don't put the root block into the free block list */
		if (i == (info->dqi_usable_bs >> 2)
		    && *blk != QT_TREEOFF) {
			put_free_dqblk(info, buf, *blk);
			*blk = 0;
		} else {
			ret = write_blk(info, *blk, buf);
			if (ret < 0)
				q_warn(KERN_ERR "VFS: Can't write quota tree "
				  "block %u.\n", *blk);
		}
	}
out_buf:
	kfree(buf);
	return ret;
}

/* Delete dquot from tree */
int qtree_delete_dquot(struct qtree_mem_dqinfo *info, struct dquot *dquot)
{
	uint tmp = QT_TREEOFF;

	if (!dquot->dq_off)	/* Even not allocated? */
		return 0;
	return remove_tree(info, dquot, &tmp, 0);
}
EXPORT_SYMBOL(qtree_delete_dquot);

/* Find entry in block */
static loff_t find_block_dqentry(struct qtree_mem_dqinfo *info,
				 struct dquot *dquot, uint blk)
{
	char *buf = getdqbuf(info->dqi_usable_bs);
	loff_t ret = 0;
	int i;
	char *ddquot;

	if (!buf)
		return -ENOMEM;
	ret = read_blk(info, blk, buf);
	if (ret < 0) {
		q_warn(KERN_ERR "VFS: Can't read quota tree block %u.\n", blk);
		goto out_buf;
	}
	ddquot = buf + sizeof(struct qt_disk_dqdbheader);
	for (i = 0; i < qtree_dqstr_in_blk(info); i++) {
		if (info->dqi_ops->is_id(ddquot, dquot))
			break;
		ddquot += info->dqi_entry_size;
	}
	if (i == qtree_dqstr_in_blk(info)) {
		q_warn(KERN_ERR "VFS: Quota for id %u referenced "
		  "but not present.\n", dquot->dq_id);
		ret = -EIO;
		goto out_buf;
	} else {
		ret = (blk << info->dqi_blocksize_bits) + sizeof(struct
		  qt_disk_dqdbheader) + i * info->dqi_entry_size;
	}
out_buf:
	kfree(buf);
	return ret;
}

/* Find entry for given id in the tree */
static loff_t find_tree_dqentry(struct qtree_mem_dqinfo *info,
				struct dquot *dquot, uint blk, int depth)
{
	char *buf = getdqbuf(info->dqi_usable_bs);
	loff_t ret = 0;
	__le32 *ref = (__le32 *)buf;

	if (!buf)
		return -ENOMEM;
	ret = read_blk(info, blk, buf);
	if (ret < 0) {
		q_warn(KERN_ERR "VFS: Can't read quota tree block %u.\n", blk);
		goto out_buf;
	}
	ret = 0;
	blk = le32_to_cpu(ref[get_index(info, dquot->dq_id, depth)]);
	if (!blk)	/* No reference? */
		goto out_buf;
	if (depth < info->dqi_qtree_depth - 1)
		ret = find_tree_dqentry(info, dquot, blk, depth+1);
	else
		ret = find_block_dqentry(info, dquot, blk);
out_buf:
	kfree(buf);
	return ret;
}

/* Find entry for given id in the tree - wrapper function */
static inline loff_t find_dqentry(struct qtree_mem_dqinfo *info,
				  struct dquot *dquot)
{
	return find_tree_dqentry(info, dquot, QT_TREEOFF, 0);
}

int qtree_read_dquot(struct qtree_mem_dqinfo *info, struct dquot *dquot)
{
	int type = dquot->dq_type;
	struct super_block *sb = dquot->dq_sb;
	loff_t offset;
	char *ddquot;
	int ret = 0;

#ifdef __QUOTA_QT_PARANOIA
	/* Invalidated quota? */
	if (!sb_dqopt(dquot->dq_sb)->files[type]) {
		printk(KERN_ERR "VFS: Quota invalidated while reading!\n");
		return -EIO;
	}
#endif
	/* Do we know offset of the dquot entry in the quota file? */
	if (!dquot->dq_off) {
		offset = find_dqentry(info, dquot);
		if (offset <= 0) {	/* Entry not present? */
			if (offset < 0)
				q_warn(KERN_ERR "VFS: Can't read quota "
				  "structure for id %u.\n", dquot->dq_id);
			dquot->dq_off = 0;
			set_bit(DQ_FAKE_B, &dquot->dq_flags);
			memset(&dquot->dq_dqb, 0, sizeof(struct mem_dqblk));
			ret = offset;
			goto out;
		}
		dquot->dq_off = offset;
	}
	ddquot = getdqbuf(info->dqi_entry_size);
	if (!ddquot)
		return -ENOMEM;
	ret = sb->s_op->quota_read(sb, type, ddquot, info->dqi_entry_size,
				   dquot->dq_off);
	if (ret != info->dqi_entry_size) {
		if (ret >= 0)
			ret = -EIO;
		q_warn(KERN_ERR "VFS: Error while reading quota "
				"structure for id %u.\n", dquot->dq_id);
		set_bit(DQ_FAKE_B, &dquot->dq_flags);
		memset(&dquot->dq_dqb, 0, sizeof(struct mem_dqblk));
		kfree(ddquot);
		goto out;
	}
	spin_lock(&dq_data_lock);
	info->dqi_ops->disk2mem_dqblk(dquot, ddquot);
	if (!dquot->dq_dqb.dqb_bhardlimit &&
	    !dquot->dq_dqb.dqb_bsoftlimit &&
	    !dquot->dq_dqb.dqb_ihardlimit &&
	    !dquot->dq_dqb.dqb_isoftlimit)
		set_bit(DQ_FAKE_B, &dquot->dq_flags);
	spin_unlock(&dq_data_lock);
	kfree(ddquot);
out:
	dqstats_inc(DQST_READS);
	return ret;
}
EXPORT_SYMBOL(qtree_read_dquot);

/* Check whether dquot should not be deleted. We know we are
 * the only one operating on dquot (thanks to dq_lock) */
int qtree_release_dquot(struct qtree_mem_dqinfo *info, struct dquot *dquot)
{
	if (test_bit(DQ_FAKE_B, &dquot->dq_flags) &&
	    !(dquot->dq_dqb.dqb_curinodes | dquot->dq_dqb.dqb_curspace))
		return qtree_delete_dquot(info, dquot);
	return 0;
}
EXPORT_SYMBOL(qtree_release_dquot);