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 #include "e2fsck.h"
15
16 /*
17 * The strategy we use for keeping track of EA refcounts is as
18 * follows. We keep a sorted array of first EA blocks and its
19 * reference counts. Once the refcount has dropped to zero, it is
20 * removed from the array to save memory space. Once the EA block is
21 * checked, its bit is set in the block_ea_map bitmap.
22 */
23 struct ea_refcount_el {
24 blk_t ea_blk;
25 int ea_count;
26 };
27
28 struct ea_refcount {
29 blk_t count;
30 blk_t size;
31 blk_t cursor;
32 struct ea_refcount_el *list;
33 };
34
ea_refcount_free(ext2_refcount_t refcount)35 void ea_refcount_free(ext2_refcount_t refcount)
36 {
37 if (!refcount)
38 return;
39
40 if (refcount->list)
41 ext2fs_free_mem(&refcount->list);
42 ext2fs_free_mem(&refcount);
43 }
44
ea_refcount_create(int size,ext2_refcount_t * ret)45 errcode_t ea_refcount_create(int size, ext2_refcount_t *ret)
46 {
47 ext2_refcount_t refcount;
48 errcode_t retval;
49 size_t bytes;
50
51 retval = ext2fs_get_mem(sizeof(struct ea_refcount), &refcount);
52 if (retval)
53 return retval;
54 memset(refcount, 0, sizeof(struct ea_refcount));
55
56 if (!size)
57 size = 500;
58 refcount->size = size;
59 bytes = (size_t) (size * sizeof(struct ea_refcount_el));
60 #ifdef DEBUG
61 printf("Refcount allocated %d entries, %d bytes.\n",
62 refcount->size, bytes);
63 #endif
64 retval = ext2fs_get_mem(bytes, &refcount->list);
65 if (retval)
66 goto errout;
67 memset(refcount->list, 0, bytes);
68
69 refcount->count = 0;
70 refcount->cursor = 0;
71
72 *ret = refcount;
73 return 0;
74
75 errout:
76 ea_refcount_free(refcount);
77 return(retval);
78 }
79
80 /*
81 * collapse_refcount() --- go through the refcount array, and get rid
82 * of any count == zero entries
83 */
refcount_collapse(ext2_refcount_t refcount)84 static void refcount_collapse(ext2_refcount_t refcount)
85 {
86 unsigned int i, j;
87 struct ea_refcount_el *list;
88
89 list = refcount->list;
90 for (i = 0, j = 0; i < refcount->count; i++) {
91 if (list[i].ea_count) {
92 if (i != j)
93 list[j] = list[i];
94 j++;
95 }
96 }
97 #if defined(DEBUG) || defined(TEST_PROGRAM)
98 printf("Refcount_collapse: size was %d, now %d\n",
99 refcount->count, j);
100 #endif
101 refcount->count = j;
102 }
103
104
105 /*
106 * insert_refcount_el() --- Insert a new entry into the sorted list at a
107 * specified position.
108 */
insert_refcount_el(ext2_refcount_t refcount,blk_t blk,int pos)109 static struct ea_refcount_el *insert_refcount_el(ext2_refcount_t refcount,
110 blk_t blk, int pos)
111 {
112 struct ea_refcount_el *el;
113 errcode_t retval;
114 blk_t new_size = 0;
115 int num;
116
117 if (refcount->count >= refcount->size) {
118 new_size = refcount->size + 100;
119 #ifdef DEBUG
120 printf("Reallocating refcount %d entries...\n", new_size);
121 #endif
122 retval = ext2fs_resize_mem((size_t) refcount->size *
123 sizeof(struct ea_refcount_el),
124 (size_t) new_size *
125 sizeof(struct ea_refcount_el),
126 &refcount->list);
127 if (retval)
128 return 0;
129 refcount->size = new_size;
130 }
131 num = (int) refcount->count - pos;
132 if (num < 0)
133 return 0; /* should never happen */
134 if (num) {
135 memmove(&refcount->list[pos+1], &refcount->list[pos],
136 sizeof(struct ea_refcount_el) * num);
137 }
138 refcount->count++;
139 el = &refcount->list[pos];
140 el->ea_count = 0;
141 el->ea_blk = blk;
142 return el;
143 }
144
145
146 /*
147 * get_refcount_el() --- given an block number, try to find refcount
148 * information in the sorted list. If the create flag is set,
149 * and we can't find an entry, create one in the sorted list.
150 */
get_refcount_el(ext2_refcount_t refcount,blk_t blk,int create)151 static struct ea_refcount_el *get_refcount_el(ext2_refcount_t refcount,
152 blk_t blk, int create)
153 {
154 float range;
155 int low, high, mid;
156 blk_t lowval, highval;
157
158 if (!refcount || !refcount->list)
159 return 0;
160 retry:
161 low = 0;
162 high = (int) refcount->count-1;
163 if (create && ((refcount->count == 0) ||
164 (blk > refcount->list[high].ea_blk))) {
165 if (refcount->count >= refcount->size)
166 refcount_collapse(refcount);
167
168 return insert_refcount_el(refcount, blk,
169 (unsigned) refcount->count);
170 }
171 if (refcount->count == 0)
172 return 0;
173
174 if (refcount->cursor >= refcount->count)
175 refcount->cursor = 0;
176 if (blk == refcount->list[refcount->cursor].ea_blk)
177 return &refcount->list[refcount->cursor++];
178 #ifdef DEBUG
179 printf("Non-cursor get_refcount_el: %u\n", blk);
180 #endif
181 while (low <= high) {
182 #if 0
183 mid = (low+high)/2;
184 #else
185 if (low == high)
186 mid = low;
187 else {
188 /* Interpolate for efficiency */
189 lowval = refcount->list[low].ea_blk;
190 highval = refcount->list[high].ea_blk;
191
192 if (blk < lowval)
193 range = 0;
194 else if (blk > highval)
195 range = 1;
196 else
197 range = ((float) (blk - lowval)) /
198 (highval - lowval);
199 mid = low + ((int) (range * (high-low)));
200 }
201 #endif
202 if (blk == refcount->list[mid].ea_blk) {
203 refcount->cursor = mid+1;
204 return &refcount->list[mid];
205 }
206 if (blk < refcount->list[mid].ea_blk)
207 high = mid-1;
208 else
209 low = mid+1;
210 }
211 /*
212 * If we need to create a new entry, it should be right at
213 * low (where high will be left at low-1).
214 */
215 if (create) {
216 if (refcount->count >= refcount->size) {
217 refcount_collapse(refcount);
218 if (refcount->count < refcount->size)
219 goto retry;
220 }
221 return insert_refcount_el(refcount, blk, low);
222 }
223 return 0;
224 }
225
ea_refcount_fetch(ext2_refcount_t refcount,blk_t blk,int * ret)226 errcode_t ea_refcount_fetch(ext2_refcount_t refcount, blk_t blk,
227 int *ret)
228 {
229 struct ea_refcount_el *el;
230
231 el = get_refcount_el(refcount, blk, 0);
232 if (!el) {
233 *ret = 0;
234 return 0;
235 }
236 *ret = el->ea_count;
237 return 0;
238 }
239
ea_refcount_increment(ext2_refcount_t refcount,blk_t blk,int * ret)240 errcode_t ea_refcount_increment(ext2_refcount_t refcount, blk_t blk, int *ret)
241 {
242 struct ea_refcount_el *el;
243
244 el = get_refcount_el(refcount, blk, 1);
245 if (!el)
246 return EXT2_ET_NO_MEMORY;
247 el->ea_count++;
248
249 if (ret)
250 *ret = el->ea_count;
251 return 0;
252 }
253
ea_refcount_decrement(ext2_refcount_t refcount,blk_t blk,int * ret)254 errcode_t ea_refcount_decrement(ext2_refcount_t refcount, blk_t blk, int *ret)
255 {
256 struct ea_refcount_el *el;
257
258 el = get_refcount_el(refcount, blk, 0);
259 if (!el || el->ea_count == 0)
260 return EXT2_ET_INVALID_ARGUMENT;
261
262 el->ea_count--;
263
264 if (ret)
265 *ret = el->ea_count;
266 return 0;
267 }
268
ea_refcount_store(ext2_refcount_t refcount,blk_t blk,int count)269 errcode_t ea_refcount_store(ext2_refcount_t refcount, blk_t blk, int count)
270 {
271 struct ea_refcount_el *el;
272
273 /*
274 * Get the refcount element
275 */
276 el = get_refcount_el(refcount, blk, count ? 1 : 0);
277 if (!el)
278 return count ? EXT2_ET_NO_MEMORY : 0;
279 el->ea_count = count;
280 return 0;
281 }
282
ext2fs_get_refcount_size(ext2_refcount_t refcount)283 blk_t ext2fs_get_refcount_size(ext2_refcount_t refcount)
284 {
285 if (!refcount)
286 return 0;
287
288 return refcount->size;
289 }
290
ea_refcount_intr_begin(ext2_refcount_t refcount)291 void ea_refcount_intr_begin(ext2_refcount_t refcount)
292 {
293 refcount->cursor = 0;
294 }
295
296
ea_refcount_intr_next(ext2_refcount_t refcount,int * ret)297 blk_t ea_refcount_intr_next(ext2_refcount_t refcount,
298 int *ret)
299 {
300 struct ea_refcount_el *list;
301
302 while (1) {
303 if (refcount->cursor >= refcount->count)
304 return 0;
305 list = refcount->list;
306 if (list[refcount->cursor].ea_count) {
307 if (ret)
308 *ret = list[refcount->cursor].ea_count;
309 return list[refcount->cursor++].ea_blk;
310 }
311 refcount->cursor++;
312 }
313 }
314
315
316 #ifdef TEST_PROGRAM
317
ea_refcount_validate(ext2_refcount_t refcount,FILE * out)318 errcode_t ea_refcount_validate(ext2_refcount_t refcount, FILE *out)
319 {
320 errcode_t ret = 0;
321 int i;
322 const char *bad = "bad refcount";
323
324 if (refcount->count > refcount->size) {
325 fprintf(out, "%s: count > size\n", bad);
326 return EXT2_ET_INVALID_ARGUMENT;
327 }
328 for (i=1; i < refcount->count; i++) {
329 if (refcount->list[i-1].ea_blk >= refcount->list[i].ea_blk) {
330 fprintf(out, "%s: list[%d].blk=%u, list[%d].blk=%u\n",
331 bad, i-1, refcount->list[i-1].ea_blk,
332 i, refcount->list[i].ea_blk);
333 ret = EXT2_ET_INVALID_ARGUMENT;
334 }
335 }
336 return ret;
337 }
338
339 #define BCODE_END 0
340 #define BCODE_CREATE 1
341 #define BCODE_FREE 2
342 #define BCODE_STORE 3
343 #define BCODE_INCR 4
344 #define BCODE_DECR 5
345 #define BCODE_FETCH 6
346 #define BCODE_VALIDATE 7
347 #define BCODE_LIST 8
348 #define BCODE_COLLAPSE 9
349
350 int bcode_program[] = {
351 BCODE_CREATE, 5,
352 BCODE_STORE, 3, 3,
353 BCODE_STORE, 4, 4,
354 BCODE_STORE, 1, 1,
355 BCODE_STORE, 8, 8,
356 BCODE_STORE, 2, 2,
357 BCODE_STORE, 4, 0,
358 BCODE_STORE, 2, 0,
359 BCODE_STORE, 6, 6,
360 BCODE_VALIDATE,
361 BCODE_STORE, 4, 4,
362 BCODE_STORE, 2, 2,
363 BCODE_FETCH, 1,
364 BCODE_FETCH, 2,
365 BCODE_INCR, 3,
366 BCODE_INCR, 3,
367 BCODE_DECR, 4,
368 BCODE_STORE, 4, 4,
369 BCODE_VALIDATE,
370 BCODE_STORE, 20, 20,
371 BCODE_STORE, 40, 40,
372 BCODE_STORE, 30, 30,
373 BCODE_STORE, 10, 10,
374 BCODE_DECR, 30,
375 BCODE_FETCH, 30,
376 BCODE_DECR, 2,
377 BCODE_DECR, 2,
378 BCODE_COLLAPSE,
379 BCODE_LIST,
380 BCODE_VALIDATE,
381 BCODE_FREE,
382 BCODE_END
383 };
384
main(int argc,char ** argv)385 int main(int argc, char **argv)
386 {
387 int i = 0;
388 ext2_refcount_t refcount;
389 int size, arg;
390 blk_t blk;
391 errcode_t retval;
392
393 while (1) {
394 switch (bcode_program[i++]) {
395 case BCODE_END:
396 exit(0);
397 case BCODE_CREATE:
398 size = bcode_program[i++];
399 retval = ea_refcount_create(size, &refcount);
400 if (retval) {
401 com_err("ea_refcount_create",
402 retval, "");
403 exit(1);
404 } else
405 printf("Creating refcount with size %d\n",
406 size);
407 break;
408 case BCODE_FREE:
409 ea_refcount_free(refcount);
410 refcount = 0;
411 printf("Freeing refcount\n");
412 break;
413 case BCODE_STORE:
414 blk = (blk_t) bcode_program[i++];
415 arg = bcode_program[i++];
416 retval = ea_refcount_store(refcount, blk, arg);
417 printf("Storing blk %u with value %d\n", blk, arg);
418 if (retval)
419 com_err("ea_refcount_store", retval, "");
420 break;
421 case BCODE_FETCH:
422 blk = (blk_t) bcode_program[i++];
423 retval = ea_refcount_fetch(refcount, blk, &arg);
424 if (retval)
425 com_err("ea_refcount_fetch", retval, "");
426 else
427 printf("bcode_fetch(%u) returns %d\n",
428 blk, arg);
429 break;
430 case BCODE_INCR:
431 blk = (blk_t) bcode_program[i++];
432 retval = ea_refcount_increment(refcount, blk,
433 &arg);
434 if (retval)
435 com_err("ea_refcount_increment", retval,
436 "");
437 else
438 printf("bcode_increment(%u) returns %d\n",
439 blk, arg);
440 break;
441 case BCODE_DECR:
442 blk = (blk_t) bcode_program[i++];
443 retval = ea_refcount_decrement(refcount, blk,
444 &arg);
445 if (retval)
446 com_err("ea_refcount_decrement", retval,
447 "while decrementing blk %u", blk);
448 else
449 printf("bcode_decrement(%u) returns %d\n",
450 blk, arg);
451 break;
452 case BCODE_VALIDATE:
453 retval = ea_refcount_validate(refcount, stderr);
454 if (retval)
455 com_err("ea_refcount_validate",
456 retval, "");
457 else
458 printf("Refcount validation OK.\n");
459 break;
460 case BCODE_LIST:
461 ea_refcount_intr_begin(refcount);
462 while (1) {
463 blk = ea_refcount_intr_next(refcount,
464 &arg);
465 if (!blk)
466 break;
467 printf("\tblk=%u, count=%d\n", blk,
468 arg);
469 }
470 break;
471 case BCODE_COLLAPSE:
472 refcount_collapse(refcount);
473 break;
474 }
475
476 }
477 }
478
479 #endif
480