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 */
26 struct ea_refcount_el {
27 blk64_t ea_blk;
28 int ea_count;
29 };
30
31 struct ea_refcount {
32 blk_t count;
33 blk_t size;
34 blk_t cursor;
35 struct ea_refcount_el *list;
36 };
37
ea_refcount_free(ext2_refcount_t refcount)38 void 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
ea_refcount_create(int size,ext2_refcount_t * ret)48 errcode_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
78 errout:
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 */
refcount_collapse(ext2_refcount_t refcount)87 static 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 */
insert_refcount_el(ext2_refcount_t refcount,blk64_t blk,int pos)112 static 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 */
get_refcount_el(ext2_refcount_t refcount,blk64_t blk,int create)154 static 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;
161 retry:
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
ea_refcount_fetch(ext2_refcount_t refcount,blk64_t blk,int * ret)208 errcode_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
ea_refcount_increment(ext2_refcount_t refcount,blk64_t blk,int * ret)222 errcode_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
ea_refcount_decrement(ext2_refcount_t refcount,blk64_t blk,int * ret)236 errcode_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
ea_refcount_store(ext2_refcount_t refcount,blk64_t blk,int count)251 errcode_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
ext2fs_get_refcount_size(ext2_refcount_t refcount)265 blk_t ext2fs_get_refcount_size(ext2_refcount_t refcount)
266 {
267 if (!refcount)
268 return 0;
269
270 return refcount->size;
271 }
272
ea_refcount_intr_begin(ext2_refcount_t refcount)273 void ea_refcount_intr_begin(ext2_refcount_t refcount)
274 {
275 refcount->cursor = 0;
276 }
277
278
ea_refcount_intr_next(ext2_refcount_t refcount,int * ret)279 blk64_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
ea_refcount_validate(ext2_refcount_t refcount,FILE * out)300 errcode_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
333 int 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
main(int argc,char ** argv)368 int 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