aboutsummaryrefslogtreecommitdiffstats
path: root/e2fsck/ea_refcount.c
blob: e66e63633d850df8c7de4d5e09f4bee35b931f4a (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
/*
 * ea_refcount.c
 *
 * Copyright (C) 2001 Theodore Ts'o.  This file may be
 * redistributed under the terms of the GNU Public License.
 */

#include "config.h"
#if HAVE_UNISTD_H
#include <unistd.h>
#endif
#include <string.h>
#include <stdio.h>

#ifdef TEST_PROGRAM
#undef ENABLE_NLS
#endif
#include "e2fsck.h"

/*
 * The strategy we use for keeping track of EA refcounts is as
 * follows.  We keep a sorted array of first EA blocks and its
 * reference counts.  Once the refcount has dropped to zero, it is
 * removed from the array to save memory space.  Once the EA block is
 * checked, its bit is set in the block_ea_map bitmap.
 */
struct ea_refcount_el {
	blk_t	ea_blk;
	int	ea_count;
};

struct ea_refcount {
	blk_t		count;
	blk_t		size;
	blk_t		cursor;
	struct ea_refcount_el	*list;
};

void ea_refcount_free(ext2_refcount_t refcount)
{
	if (!refcount)
		return;

	if (refcount->list)
		ext2fs_free_mem(&refcount->list);
	ext2fs_free_mem(&refcount);
}

errcode_t ea_refcount_create(int size, ext2_refcount_t *ret)
{
	ext2_refcount_t	refcount;
	errcode_t	retval;
	size_t		bytes;

	retval = ext2fs_get_mem(sizeof(struct ea_refcount), &refcount);
	if (retval)
		return retval;
	memset(refcount, 0, sizeof(struct ea_refcount));

	if (!size)
		size = 500;
	refcount->size = size;
	bytes = (size_t) (size * sizeof(struct ea_refcount_el));
#ifdef DEBUG
	printf("Refcount allocated %d entries, %d bytes.\n",
	       refcount->size, bytes);
#endif
	retval = ext2fs_get_mem(bytes, &refcount->list);
	if (retval)
		goto errout;
	memset(refcount->list, 0, bytes);

	refcount->count = 0;
	refcount->cursor = 0;

	*ret = refcount;
	return 0;

errout:
	ea_refcount_free(refcount);
	return(retval);
}

/*
 * collapse_refcount() --- go through the refcount array, and get rid
 * of any count == zero entries
 */
static void refcount_collapse(ext2_refcount_t refcount)
{
	unsigned int	i, j;
	struct ea_refcount_el	*list;

	list = refcount->list;
	for (i = 0, j = 0; i < refcount->count; i++) {
		if (list[i].ea_count) {
			if (i != j)
				list[j] = list[i];
			j++;
		}
	}
#if defined(DEBUG) || defined(TEST_PROGRAM)
	printf("Refcount_collapse: size was %d, now %d\n",
	       refcount->count, j);
#endif
	refcount->count = j;
}


/*
 * insert_refcount_el() --- Insert a new entry into the sorted list at a
 * 	specified position.
 */
static struct ea_refcount_el *insert_refcount_el(ext2_refcount_t refcount,
						 blk_t blk, int pos)
{
	struct ea_refcount_el 	*el;
	errcode_t		retval;
	blk_t			new_size = 0;
	int			num;

	if (refcount->count >= refcount->size) {
		new_size = refcount->size + 100;
#ifdef DEBUG
		printf("Reallocating refcount %d entries...\n", new_size);
#endif
		retval = ext2fs_resize_mem((size_t) refcount->size *
					   sizeof(struct ea_refcount_el),
					   (size_t) new_size *
					   sizeof(struct ea_refcount_el),
					   &refcount->list);
		if (retval)
			return 0;
		refcount->size = new_size;
	}
	num = (int) refcount->count - pos;
	if (num < 0)
		return 0;	/* should never happen */
	if (num) {
		memmove(&refcount->list[pos+1], &refcount->list[pos],
			sizeof(struct ea_refcount_el) * num);
	}
	refcount->count++;
	el = &refcount->list[pos];
	el->ea_count = 0;
	el->ea_blk = blk;
	return el;
}


/*
 * get_refcount_el() --- given an block number, try to find refcount
 * 	information in the sorted list.  If the create flag is set,
 * 	and we can't find an entry, create one in the sorted list.
 */
static struct ea_refcount_el *get_refcount_el(ext2_refcount_t refcount,
					      blk_t blk, int create)
{
	int	low, high, mid;

	if (!refcount || !refcount->list)
		return 0;
retry:
	low = 0;
	high = (int) refcount->count-1;
	if (create && ((refcount->count == 0) ||
		       (blk > refcount->list[high].ea_blk))) {
		if (refcount->count >= refcount->size)
			refcount_collapse(refcount);

		return insert_refcount_el(refcount, blk,
					  (unsigned) refcount->count);
	}
	if (refcount->count == 0)
		return 0;

	if (refcount->cursor >= refcount->count)
		refcount->cursor = 0;
	if (blk == refcount->list[refcount->cursor].ea_blk)
		return &refcount->list[refcount->cursor++];
#ifdef DEBUG
	printf("Non-cursor get_refcount_el: %u\n", blk);
#endif
	while (low <= high) {
		mid = (low+high)/2;
		if (blk == refcount->list[mid].ea_blk) {
			refcount->cursor = mid+1;
			return &refcount->list[mid];
		}
		if (blk < refcount->list[mid].ea_blk)
			high = mid-1;
		else
			low = mid+1;
	}
	/*
	 * If we need to create a new entry, it should be right at
	 * low (where high will be left at low-1).
	 */
	if (create) {
		if (refcount->count >= refcount->size) {
			refcount_collapse(refcount);
			if (refcount->count < refcount->size)
				goto retry;
		}
		return insert_refcount_el(refcount, blk, low);
	}
	return 0;
}

errcode_t ea_refcount_fetch(ext2_refcount_t refcount, blk_t blk,
				int *ret)
{
	struct ea_refcount_el	*el;

	el = get_refcount_el(refcount, blk, 0);
	if (!el) {
		*ret = 0;
		return 0;
	}
	*ret = el->ea_count;
	return 0;
}

errcode_t ea_refcount_increment(ext2_refcount_t refcount, blk_t blk, int *ret)
{
	struct ea_refcount_el	*el;

	el = get_refcount_el(refcount, blk, 1);
	if (!el)
		return EXT2_ET_NO_MEMORY;
	el->ea_count++;

	if (ret)
		*ret = el->ea_count;
	return 0;
}

errcode_t ea_refcount_decrement(ext2_refcount_t refcount, blk_t blk, int *ret)
{
	struct ea_refcount_el	*el;

	el = get_refcount_el(refcount, blk, 0);
	if (!el || el->ea_count == 0)
		return EXT2_ET_INVALID_ARGUMENT;

	el->ea_count--;

	if (ret)
		*ret = el->ea_count;
	return 0;
}

errcode_t ea_refcount_store(ext2_refcount_t refcount, blk_t blk, int count)
{
	struct ea_refcount_el	*el;

	/*
	 * Get the refcount element
	 */
	el = get_refcount_el(refcount, blk, count ? 1 : 0);
	if (!el)
		return count ? EXT2_ET_NO_MEMORY : 0;
	el->ea_count = count;
	return 0;
}

blk_t ext2fs_get_refcount_size(ext2_refcount_t refcount)
{
	if (!refcount)
		return 0;

	return refcount->size;
}

void ea_refcount_intr_begin(ext2_refcount_t refcount)
{
	refcount->cursor = 0;
}


blk_t ea_refcount_intr_next(ext2_refcount_t refcount,
				int *ret)
{
	struct ea_refcount_el	*list;

	while (1) {
		if (refcount->cursor >= refcount->count)
			return 0;
		list = refcount->list;
		if (list[refcount->cursor].ea_count) {
			if (ret)
				*ret = list[refcount->cursor].ea_count;
			return list[refcount->cursor++].ea_blk;
		}
		refcount->cursor++;
	}
}


#ifdef TEST_PROGRAM

errcode_t ea_refcount_validate(ext2_refcount_t refcount, FILE *out)
{
	errcode_t	ret = 0;
	int		i;
	const char *bad = "bad refcount";

	if (refcount->count > refcount->size) {
		fprintf(out, "%s: count > size\n", bad);
		return EXT2_ET_INVALID_ARGUMENT;
	}
	for (i=1; i < refcount->count; i++) {
		if (refcount->list[i-1].ea_blk >= refcount->list[i].ea_blk) {
			fprintf(out, "%s: list[%d].blk=%u, list[%d].blk=%u\n",
				bad, i-1, refcount->list[i-1].ea_blk,
				i, refcount->list[i].ea_blk);
			ret = EXT2_ET_INVALID_ARGUMENT;
		}
	}
	return ret;
}

#define BCODE_END	0
#define BCODE_CREATE	1
#define BCODE_FREE	2
#define BCODE_STORE	3
#define BCODE_INCR	4
#define BCODE_DECR	5
#define BCODE_FETCH	6
#define BCODE_VALIDATE	7
#define BCODE_LIST	8
#define BCODE_COLLAPSE 9

int bcode_program[] = {
	BCODE_CREATE, 5,
	BCODE_STORE, 3, 3,
	BCODE_STORE, 4, 4,
	BCODE_STORE, 1, 1,
	BCODE_STORE, 8, 8,
	BCODE_STORE, 2, 2,
	BCODE_STORE, 4, 0,
	BCODE_STORE, 2, 0,
	BCODE_STORE, 6, 6,
	BCODE_VALIDATE,
	BCODE_STORE, 4, 4,
	BCODE_STORE, 2, 2,
	BCODE_FETCH, 1,
	BCODE_FETCH, 2,
	BCODE_INCR, 3,
	BCODE_INCR, 3,
	BCODE_DECR, 4,
	BCODE_STORE, 4, 4,
	BCODE_VALIDATE,
	BCODE_STORE, 20, 20,
	BCODE_STORE, 40, 40,
	BCODE_STORE, 30, 30,
	BCODE_STORE, 10, 10,
	BCODE_DECR, 30,
	BCODE_FETCH, 30,
	BCODE_DECR, 2,
	BCODE_DECR, 2,
	BCODE_COLLAPSE,
	BCODE_LIST,
	BCODE_VALIDATE,
	BCODE_FREE,
	BCODE_END
};

int main(int argc, char **argv)
{
	int	i = 0;
	ext2_refcount_t refcount;
	int		size, arg;
	blk_t		blk;
	errcode_t	retval;

	while (1) {
		switch (bcode_program[i++]) {
		case BCODE_END:
			exit(0);
		case BCODE_CREATE:
			size = bcode_program[i++];
			retval = ea_refcount_create(size, &refcount);
			if (retval) {
				com_err("ea_refcount_create", retval,
					"while creating size %d", size);
				exit(1);
			} else
				printf("Creating refcount with size %d\n",
				       size);
			break;
		case BCODE_FREE:
			ea_refcount_free(refcount);
			refcount = 0;
			printf("Freeing refcount\n");
			break;
		case BCODE_STORE:
			blk = (blk_t) bcode_program[i++];
			arg = bcode_program[i++];
			printf("Storing blk %u with value %d\n", blk, arg);
			retval = ea_refcount_store(refcount, blk, arg);
			if (retval)
				com_err("ea_refcount_store", retval,
					"while storing blk %u", blk);
			break;
		case BCODE_FETCH:
			blk = (blk_t) bcode_program[i++];
			retval = ea_refcount_fetch(refcount, blk, &arg);
			if (retval)
				com_err("ea_refcount_fetch", retval,
					"while fetching blk %u", blk);
			else
				printf("bcode_fetch(%u) returns %d\n",
				       blk, arg);
			break;
		case BCODE_INCR:
			blk = (blk_t) bcode_program[i++];
			retval = ea_refcount_increment(refcount, blk, &arg);
			if (retval)
				com_err("ea_refcount_increment", retval,
					"while incrementing blk %u", blk);
			else
				printf("bcode_increment(%u) returns %d\n",
				       blk, arg);
			break;
		case BCODE_DECR:
			blk = (blk_t) bcode_program[i++];
			retval = ea_refcount_decrement(refcount, blk, &arg);
			if (retval)
				com_err("ea_refcount_decrement", retval,
					"while decrementing blk %u", blk);
			else
				printf("bcode_decrement(%u) returns %d\n",
				       blk, arg);
			break;
		case BCODE_VALIDATE:
			retval = ea_refcount_validate(refcount, stderr);
			if (retval)
				com_err("ea_refcount_validate", retval,
					"while validating");
			else
				printf("Refcount validation OK.\n");
			break;
		case BCODE_LIST:
			ea_refcount_intr_begin(refcount);
			while (1) {
				blk = ea_refcount_intr_next(refcount, &arg);
				if (!blk)
					break;
				printf("\tblk=%u, count=%d\n", blk, arg);
			}
			break;
		case BCODE_COLLAPSE:
			refcount_collapse(refcount);
			break;
		}

	}
}

#endif