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 #include "config.h"
9 #if HAVE_UNISTD_H
10 #include <unistd.h>
11 #endif
12 #include <string.h>
13 #include <stdio.h>
14
15 #ifdef TEST_PROGRAM
16 #undef ENABLE_NLS
17 #endif
18 #include "e2fsck.h"
19
20 /*
21 * The strategy we use for keeping track of EA refcounts is as
22 * follows. We keep a sorted array of first EA blocks and its
23 * reference counts. Once the refcount has dropped to zero, it is
24 * removed from the array to save memory space. Once the EA block is
25 * checked, its bit is set in the block_ea_map bitmap.
26 */
27 struct ea_refcount_el {
28 blk64_t ea_blk;
29 int ea_count;
30 };
31
32 struct ea_refcount {
33 blk_t count;
34 blk_t size;
35 blk_t cursor;
36 struct ea_refcount_el *list;
37 };
38
ea_refcount_free(ext2_refcount_t refcount)39 void ea_refcount_free(ext2_refcount_t refcount)
40 {
41 if (!refcount)
42 return;
43
44 if (refcount->list)
45 ext2fs_free_mem(&refcount->list);
46 ext2fs_free_mem(&refcount);
47 }
48
ea_refcount_create(int size,ext2_refcount_t * ret)49 errcode_t ea_refcount_create(int size, ext2_refcount_t *ret)
50 {
51 ext2_refcount_t refcount;
52 errcode_t retval;
53 size_t bytes;
54
55 retval = ext2fs_get_mem(sizeof(struct ea_refcount), &refcount);
56 if (retval)
57 return retval;
58 memset(refcount, 0, sizeof(struct ea_refcount));
59
60 if (!size)
61 size = 500;
62 refcount->size = size;
63 bytes = (size_t) (size * sizeof(struct ea_refcount_el));
64 #ifdef DEBUG
65 printf("Refcount allocated %d entries, %d bytes.\n",
66 refcount->size, bytes);
67 #endif
68 retval = ext2fs_get_mem(bytes, &refcount->list);
69 if (retval)
70 goto errout;
71 memset(refcount->list, 0, bytes);
72
73 refcount->count = 0;
74 refcount->cursor = 0;
75
76 *ret = refcount;
77 return 0;
78
79 errout:
80 ea_refcount_free(refcount);
81 return(retval);
82 }
83
84 /*
85 * collapse_refcount() --- go through the refcount array, and get rid
86 * of any count == zero entries
87 */
refcount_collapse(ext2_refcount_t refcount)88 static void refcount_collapse(ext2_refcount_t refcount)
89 {
90 unsigned int i, j;
91 struct ea_refcount_el *list;
92
93 list = refcount->list;
94 for (i = 0, j = 0; i < refcount->count; i++) {
95 if (list[i].ea_count) {
96 if (i != j)
97 list[j] = list[i];
98 j++;
99 }
100 }
101 #if defined(DEBUG) || defined(TEST_PROGRAM)
102 printf("Refcount_collapse: size was %d, now %d\n",
103 refcount->count, j);
104 #endif
105 refcount->count = j;
106 }
107
108
109 /*
110 * insert_refcount_el() --- Insert a new entry into the sorted list at a
111 * specified position.
112 */
insert_refcount_el(ext2_refcount_t refcount,blk64_t blk,int pos)113 static struct ea_refcount_el *insert_refcount_el(ext2_refcount_t refcount,
114 blk64_t blk, int pos)
115 {
116 struct ea_refcount_el *el;
117 errcode_t retval;
118 blk_t new_size = 0;
119 int num;
120
121 if (refcount->count >= refcount->size) {
122 new_size = refcount->size + 100;
123 #ifdef DEBUG
124 printf("Reallocating refcount %d entries...\n", new_size);
125 #endif
126 retval = ext2fs_resize_mem((size_t) refcount->size *
127 sizeof(struct ea_refcount_el),
128 (size_t) new_size *
129 sizeof(struct ea_refcount_el),
130 &refcount->list);
131 if (retval)
132 return 0;
133 refcount->size = new_size;
134 }
135 num = (int) refcount->count - pos;
136 if (num < 0)
137 return 0; /* should never happen */
138 if (num) {
139 memmove(&refcount->list[pos+1], &refcount->list[pos],
140 sizeof(struct ea_refcount_el) * num);
141 }
142 refcount->count++;
143 el = &refcount->list[pos];
144 el->ea_count = 0;
145 el->ea_blk = blk;
146 return el;
147 }
148
149
150 /*
151 * get_refcount_el() --- given an block number, try to find refcount
152 * information in the sorted list. If the create flag is set,
153 * and we can't find an entry, create one in the sorted list.
154 */
get_refcount_el(ext2_refcount_t refcount,blk64_t blk,int create)155 static struct ea_refcount_el *get_refcount_el(ext2_refcount_t refcount,
156 blk64_t blk, int create)
157 {
158 int low, high, mid;
159
160 if (!refcount || !refcount->list)
161 return 0;
162 retry:
163 low = 0;
164 high = (int) refcount->count-1;
165 if (create && ((refcount->count == 0) ||
166 (blk > refcount->list[high].ea_blk))) {
167 if (refcount->count >= refcount->size)
168 refcount_collapse(refcount);
169
170 return insert_refcount_el(refcount, blk,
171 (unsigned) refcount->count);
172 }
173 if (refcount->count == 0)
174 return 0;
175
176 if (refcount->cursor >= refcount->count)
177 refcount->cursor = 0;
178 if (blk == refcount->list[refcount->cursor].ea_blk)
179 return &refcount->list[refcount->cursor++];
180 #ifdef DEBUG
181 printf("Non-cursor get_refcount_el: %u\n", blk);
182 #endif
183 while (low <= high) {
184 mid = (low+high)/2;
185 if (blk == refcount->list[mid].ea_blk) {
186 refcount->cursor = mid+1;
187 return &refcount->list[mid];
188 }
189 if (blk < refcount->list[mid].ea_blk)
190 high = mid-1;
191 else
192 low = mid+1;
193 }
194 /*
195 * If we need to create a new entry, it should be right at
196 * low (where high will be left at low-1).
197 */
198 if (create) {
199 if (refcount->count >= refcount->size) {
200 refcount_collapse(refcount);
201 if (refcount->count < refcount->size)
202 goto retry;
203 }
204 return insert_refcount_el(refcount, blk, low);
205 }
206 return 0;
207 }
208
ea_refcount_fetch(ext2_refcount_t refcount,blk64_t blk,int * ret)209 errcode_t ea_refcount_fetch(ext2_refcount_t refcount, blk64_t blk,
210 int *ret)
211 {
212 struct ea_refcount_el *el;
213
214 el = get_refcount_el(refcount, blk, 0);
215 if (!el) {
216 *ret = 0;
217 return 0;
218 }
219 *ret = el->ea_count;
220 return 0;
221 }
222
ea_refcount_increment(ext2_refcount_t refcount,blk64_t blk,int * ret)223 errcode_t ea_refcount_increment(ext2_refcount_t refcount, blk64_t blk, int *ret)
224 {
225 struct ea_refcount_el *el;
226
227 el = get_refcount_el(refcount, blk, 1);
228 if (!el)
229 return EXT2_ET_NO_MEMORY;
230 el->ea_count++;
231
232 if (ret)
233 *ret = el->ea_count;
234 return 0;
235 }
236
ea_refcount_decrement(ext2_refcount_t refcount,blk64_t blk,int * ret)237 errcode_t ea_refcount_decrement(ext2_refcount_t refcount, blk64_t blk, int *ret)
238 {
239 struct ea_refcount_el *el;
240
241 el = get_refcount_el(refcount, blk, 0);
242 if (!el || el->ea_count == 0)
243 return EXT2_ET_INVALID_ARGUMENT;
244
245 el->ea_count--;
246
247 if (ret)
248 *ret = el->ea_count;
249 return 0;
250 }
251
ea_refcount_store(ext2_refcount_t refcount,blk64_t blk,int count)252 errcode_t ea_refcount_store(ext2_refcount_t refcount, blk64_t blk, int count)
253 {
254 struct ea_refcount_el *el;
255
256 /*
257 * Get the refcount element
258 */
259 el = get_refcount_el(refcount, blk, count ? 1 : 0);
260 if (!el)
261 return count ? EXT2_ET_NO_MEMORY : 0;
262 el->ea_count = count;
263 return 0;
264 }
265
ext2fs_get_refcount_size(ext2_refcount_t refcount)266 blk_t ext2fs_get_refcount_size(ext2_refcount_t refcount)
267 {
268 if (!refcount)
269 return 0;
270
271 return refcount->size;
272 }
273
ea_refcount_intr_begin(ext2_refcount_t refcount)274 void ea_refcount_intr_begin(ext2_refcount_t refcount)
275 {
276 refcount->cursor = 0;
277 }
278
279
ea_refcount_intr_next(ext2_refcount_t refcount,int * ret)280 blk64_t ea_refcount_intr_next(ext2_refcount_t refcount,
281 int *ret)
282 {
283 struct ea_refcount_el *list;
284
285 while (1) {
286 if (refcount->cursor >= refcount->count)
287 return 0;
288 list = refcount->list;
289 if (list[refcount->cursor].ea_count) {
290 if (ret)
291 *ret = list[refcount->cursor].ea_count;
292 return list[refcount->cursor++].ea_blk;
293 }
294 refcount->cursor++;
295 }
296 }
297
298
299 #ifdef TEST_PROGRAM
300
ea_refcount_validate(ext2_refcount_t refcount,FILE * out)301 errcode_t ea_refcount_validate(ext2_refcount_t refcount, FILE *out)
302 {
303 errcode_t ret = 0;
304 int i;
305 const char *bad = "bad refcount";
306
307 if (refcount->count > refcount->size) {
308 fprintf(out, "%s: count > size\n", bad);
309 return EXT2_ET_INVALID_ARGUMENT;
310 }
311 for (i=1; i < refcount->count; i++) {
312 if (refcount->list[i-1].ea_blk >= refcount->list[i].ea_blk) {
313 fprintf(out,
314 "%s: list[%d].blk=%llu, list[%d].blk=%llu\n",
315 bad, i-1, refcount->list[i-1].ea_blk,
316 i, refcount->list[i].ea_blk);
317 ret = EXT2_ET_INVALID_ARGUMENT;
318 }
319 }
320 return ret;
321 }
322
323 #define BCODE_END 0
324 #define BCODE_CREATE 1
325 #define BCODE_FREE 2
326 #define BCODE_STORE 3
327 #define BCODE_INCR 4
328 #define BCODE_DECR 5
329 #define BCODE_FETCH 6
330 #define BCODE_VALIDATE 7
331 #define BCODE_LIST 8
332 #define BCODE_COLLAPSE 9
333
334 int bcode_program[] = {
335 BCODE_CREATE, 5,
336 BCODE_STORE, 3, 3,
337 BCODE_STORE, 4, 4,
338 BCODE_STORE, 1, 1,
339 BCODE_STORE, 8, 8,
340 BCODE_STORE, 2, 2,
341 BCODE_STORE, 4, 0,
342 BCODE_STORE, 2, 0,
343 BCODE_STORE, 6, 6,
344 BCODE_VALIDATE,
345 BCODE_STORE, 4, 4,
346 BCODE_STORE, 2, 2,
347 BCODE_FETCH, 1,
348 BCODE_FETCH, 2,
349 BCODE_INCR, 3,
350 BCODE_INCR, 3,
351 BCODE_DECR, 4,
352 BCODE_STORE, 4, 4,
353 BCODE_VALIDATE,
354 BCODE_STORE, 20, 20,
355 BCODE_STORE, 40, 40,
356 BCODE_STORE, 30, 30,
357 BCODE_STORE, 10, 10,
358 BCODE_DECR, 30,
359 BCODE_FETCH, 30,
360 BCODE_DECR, 2,
361 BCODE_DECR, 2,
362 BCODE_COLLAPSE,
363 BCODE_LIST,
364 BCODE_VALIDATE,
365 BCODE_FREE,
366 BCODE_END
367 };
368
main(int argc,char ** argv)369 int main(int argc, char **argv)
370 {
371 int i = 0;
372 ext2_refcount_t refcount;
373 int size, arg;
374 blk64_t blk;
375 errcode_t retval;
376
377 while (1) {
378 switch (bcode_program[i++]) {
379 case BCODE_END:
380 exit(0);
381 case BCODE_CREATE:
382 size = bcode_program[i++];
383 retval = ea_refcount_create(size, &refcount);
384 if (retval) {
385 com_err("ea_refcount_create", retval,
386 "while creating size %d", size);
387 exit(1);
388 } else
389 printf("Creating refcount with size %d\n",
390 size);
391 break;
392 case BCODE_FREE:
393 ea_refcount_free(refcount);
394 refcount = 0;
395 printf("Freeing refcount\n");
396 break;
397 case BCODE_STORE:
398 blk = (blk_t) bcode_program[i++];
399 arg = bcode_program[i++];
400 printf("Storing blk %llu with value %d\n", blk, arg);
401 retval = ea_refcount_store(refcount, blk, arg);
402 if (retval)
403 com_err("ea_refcount_store", retval,
404 "while storing blk %llu", blk);
405 break;
406 case BCODE_FETCH:
407 blk = (blk_t) bcode_program[i++];
408 retval = ea_refcount_fetch(refcount, blk, &arg);
409 if (retval)
410 com_err("ea_refcount_fetch", retval,
411 "while fetching blk %llu", blk);
412 else
413 printf("bcode_fetch(%llu) returns %d\n",
414 blk, arg);
415 break;
416 case BCODE_INCR:
417 blk = (blk_t) bcode_program[i++];
418 retval = ea_refcount_increment(refcount, blk, &arg);
419 if (retval)
420 com_err("ea_refcount_increment", retval,
421 "while incrementing blk %llu", blk);
422 else
423 printf("bcode_increment(%llu) returns %d\n",
424 blk, arg);
425 break;
426 case BCODE_DECR:
427 blk = (blk_t) bcode_program[i++];
428 retval = ea_refcount_decrement(refcount, blk, &arg);
429 if (retval)
430 com_err("ea_refcount_decrement", retval,
431 "while decrementing blk %llu", blk);
432 else
433 printf("bcode_decrement(%llu) returns %d\n",
434 blk, arg);
435 break;
436 case BCODE_VALIDATE:
437 retval = ea_refcount_validate(refcount, stderr);
438 if (retval)
439 com_err("ea_refcount_validate", retval,
440 "while validating");
441 else
442 printf("Refcount validation OK.\n");
443 break;
444 case BCODE_LIST:
445 ea_refcount_intr_begin(refcount);
446 while (1) {
447 blk = ea_refcount_intr_next(refcount, &arg);
448 if (!blk)
449 break;
450 printf("\tblk=%llu, count=%d\n", blk, arg);
451 }
452 break;
453 case BCODE_COLLAPSE:
454 refcount_collapse(refcount);
455 break;
456 }
457
458 }
459 }
460
461 #endif
462