1/*
2 * ea_refcount.c
3 *
4 * Copyright (C) 2001 Theodore Ts'o.  This file may be
5 * redistributed under the terms of the GNU Public License.
6 */
7
8#if HAVE_UNISTD_H
9#include <unistd.h>
10#endif
11#include <string.h>
12#include <stdio.h>
13
14#ifdef TEST_PROGRAM
15#undef ENABLE_NLS
16#endif
17#include "e2fsck.h"
18
19/*
20 * The strategy we use for keeping track of EA refcounts is as
21 * follows.  We keep a sorted array of first EA blocks and its
22 * reference counts.  Once the refcount has dropped to zero, it is
23 * removed from the array to save memory space.  Once the EA block is
24 * checked, its bit is set in the block_ea_map bitmap.
25 */
26struct ea_refcount_el {
27	blk64_t	ea_blk;
28	int	ea_count;
29};
30
31struct ea_refcount {
32	blk_t		count;
33	blk_t		size;
34	blk_t		cursor;
35	struct ea_refcount_el	*list;
36};
37
38void ea_refcount_free(ext2_refcount_t refcount)
39{
40	if (!refcount)
41		return;
42
43	if (refcount->list)
44		ext2fs_free_mem(&refcount->list);
45	ext2fs_free_mem(&refcount);
46}
47
48errcode_t ea_refcount_create(int size, ext2_refcount_t *ret)
49{
50	ext2_refcount_t	refcount;
51	errcode_t	retval;
52	size_t		bytes;
53
54	retval = ext2fs_get_mem(sizeof(struct ea_refcount), &refcount);
55	if (retval)
56		return retval;
57	memset(refcount, 0, sizeof(struct ea_refcount));
58
59	if (!size)
60		size = 500;
61	refcount->size = size;
62	bytes = (size_t) (size * sizeof(struct ea_refcount_el));
63#ifdef DEBUG
64	printf("Refcount allocated %d entries, %d bytes.\n",
65	       refcount->size, bytes);
66#endif
67	retval = ext2fs_get_mem(bytes, &refcount->list);
68	if (retval)
69		goto errout;
70	memset(refcount->list, 0, bytes);
71
72	refcount->count = 0;
73	refcount->cursor = 0;
74
75	*ret = refcount;
76	return 0;
77
78errout:
79	ea_refcount_free(refcount);
80	return(retval);
81}
82
83/*
84 * collapse_refcount() --- go through the refcount array, and get rid
85 * of any count == zero entries
86 */
87static void refcount_collapse(ext2_refcount_t refcount)
88{
89	unsigned int	i, j;
90	struct ea_refcount_el	*list;
91
92	list = refcount->list;
93	for (i = 0, j = 0; i < refcount->count; i++) {
94		if (list[i].ea_count) {
95			if (i != j)
96				list[j] = list[i];
97			j++;
98		}
99	}
100#if defined(DEBUG) || defined(TEST_PROGRAM)
101	printf("Refcount_collapse: size was %d, now %d\n",
102	       refcount->count, j);
103#endif
104	refcount->count = j;
105}
106
107
108/*
109 * insert_refcount_el() --- Insert a new entry into the sorted list at a
110 * 	specified position.
111 */
112static struct ea_refcount_el *insert_refcount_el(ext2_refcount_t refcount,
113						 blk64_t blk, int pos)
114{
115	struct ea_refcount_el 	*el;
116	errcode_t		retval;
117	blk_t			new_size = 0;
118	int			num;
119
120	if (refcount->count >= refcount->size) {
121		new_size = refcount->size + 100;
122#ifdef DEBUG
123		printf("Reallocating refcount %d entries...\n", new_size);
124#endif
125		retval = ext2fs_resize_mem((size_t) refcount->size *
126					   sizeof(struct ea_refcount_el),
127					   (size_t) new_size *
128					   sizeof(struct ea_refcount_el),
129					   &refcount->list);
130		if (retval)
131			return 0;
132		refcount->size = new_size;
133	}
134	num = (int) refcount->count - pos;
135	if (num < 0)
136		return 0;	/* should never happen */
137	if (num) {
138		memmove(&refcount->list[pos+1], &refcount->list[pos],
139			sizeof(struct ea_refcount_el) * num);
140	}
141	refcount->count++;
142	el = &refcount->list[pos];
143	el->ea_count = 0;
144	el->ea_blk = blk;
145	return el;
146}
147
148
149/*
150 * get_refcount_el() --- given an block number, try to find refcount
151 * 	information in the sorted list.  If the create flag is set,
152 * 	and we can't find an entry, create one in the sorted list.
153 */
154static struct ea_refcount_el *get_refcount_el(ext2_refcount_t refcount,
155					      blk64_t blk, int create)
156{
157	int	low, high, mid;
158
159	if (!refcount || !refcount->list)
160		return 0;
161retry:
162	low = 0;
163	high = (int) refcount->count-1;
164	if (create && ((refcount->count == 0) ||
165		       (blk > refcount->list[high].ea_blk))) {
166		if (refcount->count >= refcount->size)
167			refcount_collapse(refcount);
168
169		return insert_refcount_el(refcount, blk,
170					  (unsigned) refcount->count);
171	}
172	if (refcount->count == 0)
173		return 0;
174
175	if (refcount->cursor >= refcount->count)
176		refcount->cursor = 0;
177	if (blk == refcount->list[refcount->cursor].ea_blk)
178		return &refcount->list[refcount->cursor++];
179#ifdef DEBUG
180	printf("Non-cursor get_refcount_el: %u\n", blk);
181#endif
182	while (low <= high) {
183		mid = (low+high)/2;
184		if (blk == refcount->list[mid].ea_blk) {
185			refcount->cursor = mid+1;
186			return &refcount->list[mid];
187		}
188		if (blk < refcount->list[mid].ea_blk)
189			high = mid-1;
190		else
191			low = mid+1;
192	}
193	/*
194	 * If we need to create a new entry, it should be right at
195	 * low (where high will be left at low-1).
196	 */
197	if (create) {
198		if (refcount->count >= refcount->size) {
199			refcount_collapse(refcount);
200			if (refcount->count < refcount->size)
201				goto retry;
202		}
203		return insert_refcount_el(refcount, blk, low);
204	}
205	return 0;
206}
207
208errcode_t ea_refcount_fetch(ext2_refcount_t refcount, blk64_t blk,
209				int *ret)
210{
211	struct ea_refcount_el	*el;
212
213	el = get_refcount_el(refcount, blk, 0);
214	if (!el) {
215		*ret = 0;
216		return 0;
217	}
218	*ret = el->ea_count;
219	return 0;
220}
221
222errcode_t ea_refcount_increment(ext2_refcount_t refcount, blk64_t blk, int *ret)
223{
224	struct ea_refcount_el	*el;
225
226	el = get_refcount_el(refcount, blk, 1);
227	if (!el)
228		return EXT2_ET_NO_MEMORY;
229	el->ea_count++;
230
231	if (ret)
232		*ret = el->ea_count;
233	return 0;
234}
235
236errcode_t ea_refcount_decrement(ext2_refcount_t refcount, blk64_t blk, int *ret)
237{
238	struct ea_refcount_el	*el;
239
240	el = get_refcount_el(refcount, blk, 0);
241	if (!el || el->ea_count == 0)
242		return EXT2_ET_INVALID_ARGUMENT;
243
244	el->ea_count--;
245
246	if (ret)
247		*ret = el->ea_count;
248	return 0;
249}
250
251errcode_t ea_refcount_store(ext2_refcount_t refcount, blk64_t blk, int count)
252{
253	struct ea_refcount_el	*el;
254
255	/*
256	 * Get the refcount element
257	 */
258	el = get_refcount_el(refcount, blk, count ? 1 : 0);
259	if (!el)
260		return count ? EXT2_ET_NO_MEMORY : 0;
261	el->ea_count = count;
262	return 0;
263}
264
265blk_t ext2fs_get_refcount_size(ext2_refcount_t refcount)
266{
267	if (!refcount)
268		return 0;
269
270	return refcount->size;
271}
272
273void ea_refcount_intr_begin(ext2_refcount_t refcount)
274{
275	refcount->cursor = 0;
276}
277
278
279blk64_t ea_refcount_intr_next(ext2_refcount_t refcount,
280				int *ret)
281{
282	struct ea_refcount_el	*list;
283
284	while (1) {
285		if (refcount->cursor >= refcount->count)
286			return 0;
287		list = refcount->list;
288		if (list[refcount->cursor].ea_count) {
289			if (ret)
290				*ret = list[refcount->cursor].ea_count;
291			return list[refcount->cursor++].ea_blk;
292		}
293		refcount->cursor++;
294	}
295}
296
297
298#ifdef TEST_PROGRAM
299
300errcode_t ea_refcount_validate(ext2_refcount_t refcount, FILE *out)
301{
302	errcode_t	ret = 0;
303	int		i;
304	const char *bad = "bad refcount";
305
306	if (refcount->count > refcount->size) {
307		fprintf(out, "%s: count > size\n", bad);
308		return EXT2_ET_INVALID_ARGUMENT;
309	}
310	for (i=1; i < refcount->count; i++) {
311		if (refcount->list[i-1].ea_blk >= refcount->list[i].ea_blk) {
312			fprintf(out,
313				"%s: list[%d].blk=%llu, list[%d].blk=%llu\n",
314				bad, i-1, refcount->list[i-1].ea_blk,
315				i, refcount->list[i].ea_blk);
316			ret = EXT2_ET_INVALID_ARGUMENT;
317		}
318	}
319	return ret;
320}
321
322#define BCODE_END	0
323#define BCODE_CREATE	1
324#define BCODE_FREE	2
325#define BCODE_STORE	3
326#define BCODE_INCR	4
327#define BCODE_DECR	5
328#define BCODE_FETCH	6
329#define BCODE_VALIDATE	7
330#define BCODE_LIST	8
331#define BCODE_COLLAPSE 9
332
333int bcode_program[] = {
334	BCODE_CREATE, 5,
335	BCODE_STORE, 3, 3,
336	BCODE_STORE, 4, 4,
337	BCODE_STORE, 1, 1,
338	BCODE_STORE, 8, 8,
339	BCODE_STORE, 2, 2,
340	BCODE_STORE, 4, 0,
341	BCODE_STORE, 2, 0,
342	BCODE_STORE, 6, 6,
343	BCODE_VALIDATE,
344	BCODE_STORE, 4, 4,
345	BCODE_STORE, 2, 2,
346	BCODE_FETCH, 1,
347	BCODE_FETCH, 2,
348	BCODE_INCR, 3,
349	BCODE_INCR, 3,
350	BCODE_DECR, 4,
351	BCODE_STORE, 4, 4,
352	BCODE_VALIDATE,
353	BCODE_STORE, 20, 20,
354	BCODE_STORE, 40, 40,
355	BCODE_STORE, 30, 30,
356	BCODE_STORE, 10, 10,
357	BCODE_DECR, 30,
358	BCODE_FETCH, 30,
359	BCODE_DECR, 2,
360	BCODE_DECR, 2,
361	BCODE_COLLAPSE,
362	BCODE_LIST,
363	BCODE_VALIDATE,
364	BCODE_FREE,
365	BCODE_END
366};
367
368int main(int argc, char **argv)
369{
370	int	i = 0;
371	ext2_refcount_t refcount;
372	int		size, arg;
373	blk64_t		blk;
374	errcode_t	retval;
375
376	while (1) {
377		switch (bcode_program[i++]) {
378		case BCODE_END:
379			exit(0);
380		case BCODE_CREATE:
381			size = bcode_program[i++];
382			retval = ea_refcount_create(size, &refcount);
383			if (retval) {
384				com_err("ea_refcount_create", retval,
385					"while creating size %d", size);
386				exit(1);
387			} else
388				printf("Creating refcount with size %d\n",
389				       size);
390			break;
391		case BCODE_FREE:
392			ea_refcount_free(refcount);
393			refcount = 0;
394			printf("Freeing refcount\n");
395			break;
396		case BCODE_STORE:
397			blk = (blk_t) bcode_program[i++];
398			arg = bcode_program[i++];
399			printf("Storing blk %llu with value %d\n", blk, arg);
400			retval = ea_refcount_store(refcount, blk, arg);
401			if (retval)
402				com_err("ea_refcount_store", retval,
403					"while storing blk %llu", blk);
404			break;
405		case BCODE_FETCH:
406			blk = (blk_t) bcode_program[i++];
407			retval = ea_refcount_fetch(refcount, blk, &arg);
408			if (retval)
409				com_err("ea_refcount_fetch", retval,
410					"while fetching blk %llu", blk);
411			else
412				printf("bcode_fetch(%llu) returns %d\n",
413				       blk, arg);
414			break;
415		case BCODE_INCR:
416			blk = (blk_t) bcode_program[i++];
417			retval = ea_refcount_increment(refcount, blk, &arg);
418			if (retval)
419				com_err("ea_refcount_increment", retval,
420					"while incrementing blk %llu", blk);
421			else
422				printf("bcode_increment(%llu) returns %d\n",
423				       blk, arg);
424			break;
425		case BCODE_DECR:
426			blk = (blk_t) bcode_program[i++];
427			retval = ea_refcount_decrement(refcount, blk, &arg);
428			if (retval)
429				com_err("ea_refcount_decrement", retval,
430					"while decrementing blk %llu", blk);
431			else
432				printf("bcode_decrement(%llu) returns %d\n",
433				       blk, arg);
434			break;
435		case BCODE_VALIDATE:
436			retval = ea_refcount_validate(refcount, stderr);
437			if (retval)
438				com_err("ea_refcount_validate", retval,
439					"while validating");
440			else
441				printf("Refcount validation OK.\n");
442			break;
443		case BCODE_LIST:
444			ea_refcount_intr_begin(refcount);
445			while (1) {
446				blk = ea_refcount_intr_next(refcount, &arg);
447				if (!blk)
448					break;
449				printf("\tblk=%llu, count=%d\n", blk, arg);
450			}
451			break;
452		case BCODE_COLLAPSE:
453			refcount_collapse(refcount);
454			break;
455		}
456
457	}
458}
459
460#endif
461