4 * Copyright (C) 2001 Theodore Ts'o. This file may be
5 * redistributed under the terms of the GNU Public License.
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.
23 struct ea_refcount_el {
32 struct ea_refcount_el *list;
35 void ea_refcount_free(ext2_refcount_t refcount)
41 ext2fs_free_mem(&refcount->list);
42 ext2fs_free_mem(&refcount);
45 errcode_t ea_refcount_create(int size, ext2_refcount_t *ret)
47 ext2_refcount_t refcount;
51 retval = ext2fs_get_mem(sizeof(struct ea_refcount), &refcount);
54 memset(refcount, 0, sizeof(struct ea_refcount));
58 refcount->size = size;
59 bytes = (size_t) (size * sizeof(struct ea_refcount_el));
61 printf("Refcount allocated %d entries, %d bytes.\n",
62 refcount->size, bytes);
64 retval = ext2fs_get_mem(bytes, &refcount->list);
67 memset(refcount->list, 0, bytes);
76 ea_refcount_free(refcount);
81 * collapse_refcount() --- go through the refcount array, and get rid
82 * of any count == zero entries
84 static void refcount_collapse(ext2_refcount_t refcount)
87 struct ea_refcount_el *list;
89 list = refcount->list;
90 for (i = 0, j = 0; i < refcount->count; i++) {
91 if (list[i].ea_count) {
97 #if defined(DEBUG) || defined(TEST_PROGRAM)
98 printf("Refcount_collapse: size was %d, now %d\n",
106 * insert_refcount_el() --- Insert a new entry into the sorted list at a
107 * specified position.
109 static struct ea_refcount_el *insert_refcount_el(ext2_refcount_t refcount,
112 struct ea_refcount_el *el;
117 if (refcount->count >= refcount->size) {
118 new_size = refcount->size + 100;
120 printf("Reallocating refcount %d entries...\n", new_size);
122 retval = ext2fs_resize_mem((size_t) refcount->size *
123 sizeof(struct ea_refcount_el),
125 sizeof(struct ea_refcount_el),
129 refcount->size = new_size;
131 num = (int) refcount->count - pos;
133 return 0; /* should never happen */
135 memmove(&refcount->list[pos+1], &refcount->list[pos],
136 sizeof(struct ea_refcount_el) * num);
139 el = &refcount->list[pos];
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.
151 static struct ea_refcount_el *get_refcount_el(ext2_refcount_t refcount,
152 blk_t blk, int create)
156 blk_t lowval, highval;
158 if (!refcount || !refcount->list)
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);
168 return insert_refcount_el(refcount, blk,
169 (unsigned) refcount->count);
171 if (refcount->count == 0)
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++];
179 printf("Non-cursor get_refcount_el: %u\n", blk);
181 while (low <= high) {
188 /* Interpolate for efficiency */
189 lowval = refcount->list[low].ea_blk;
190 highval = refcount->list[high].ea_blk;
194 else if (blk > highval)
197 range = ((float) (blk - lowval)) /
199 mid = low + ((int) (range * (high-low)));
202 if (blk == refcount->list[mid].ea_blk) {
203 refcount->cursor = mid+1;
204 return &refcount->list[mid];
206 if (blk < refcount->list[mid].ea_blk)
212 * If we need to create a new entry, it should be right at
213 * low (where high will be left at low-1).
216 if (refcount->count >= refcount->size) {
217 refcount_collapse(refcount);
218 if (refcount->count < refcount->size)
221 return insert_refcount_el(refcount, blk, low);
226 errcode_t ea_refcount_fetch(ext2_refcount_t refcount, blk_t blk,
229 struct ea_refcount_el *el;
231 el = get_refcount_el(refcount, blk, 0);
240 errcode_t ea_refcount_increment(ext2_refcount_t refcount, blk_t blk, int *ret)
242 struct ea_refcount_el *el;
244 el = get_refcount_el(refcount, blk, 1);
246 return EXT2_ET_NO_MEMORY;
254 errcode_t ea_refcount_decrement(ext2_refcount_t refcount, blk_t blk, int *ret)
256 struct ea_refcount_el *el;
258 el = get_refcount_el(refcount, blk, 0);
259 if (!el || el->ea_count == 0)
260 return EXT2_ET_INVALID_ARGUMENT;
269 errcode_t ea_refcount_store(ext2_refcount_t refcount, blk_t blk, int count)
271 struct ea_refcount_el *el;
274 * Get the refcount element
276 el = get_refcount_el(refcount, blk, count ? 1 : 0);
278 return count ? EXT2_ET_NO_MEMORY : 0;
279 el->ea_count = count;
283 blk_t ext2fs_get_refcount_size(ext2_refcount_t refcount)
288 return refcount->size;
291 void ea_refcount_intr_begin(ext2_refcount_t refcount)
293 refcount->cursor = 0;
297 blk_t ea_refcount_intr_next(ext2_refcount_t refcount,
300 struct ea_refcount_el *list;
303 if (refcount->cursor >= refcount->count)
305 list = refcount->list;
306 if (list[refcount->cursor].ea_count) {
308 *ret = list[refcount->cursor].ea_count;
309 return list[refcount->cursor++].ea_blk;
318 errcode_t ea_refcount_validate(ext2_refcount_t refcount, FILE *out)
322 const char *bad = "bad refcount";
324 if (refcount->count > refcount->size) {
325 fprintf(out, "%s: count > size\n", bad);
326 return EXT2_ET_INVALID_ARGUMENT;
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;
340 #define BCODE_CREATE 1
342 #define BCODE_STORE 3
345 #define BCODE_FETCH 6
346 #define BCODE_VALIDATE 7
348 #define BCODE_COLLAPSE 9
350 int bcode_program[] = {
385 int main(int argc, char **argv)
388 ext2_refcount_t refcount;
394 switch (bcode_program[i++]) {
398 size = bcode_program[i++];
399 retval = ea_refcount_create(size, &refcount);
401 com_err("ea_refcount_create",
405 printf("Creating refcount with size %d\n",
409 ea_refcount_free(refcount);
411 printf("Freeing refcount\n");
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);
419 com_err("ea_refcount_store", retval, "");
422 blk = (blk_t) bcode_program[i++];
423 retval = ea_refcount_fetch(refcount, blk, &arg);
425 com_err("ea_refcount_fetch", retval, "");
427 printf("bcode_fetch(%u) returns %d\n",
431 blk = (blk_t) bcode_program[i++];
432 retval = ea_refcount_increment(refcount, blk,
435 com_err("ea_refcount_increment", retval,
438 printf("bcode_increment(%u) returns %d\n",
442 blk = (blk_t) bcode_program[i++];
443 retval = ea_refcount_decrement(refcount, blk,
446 com_err("ea_refcount_decrement", retval,
447 "while decrementing blk %u", blk);
449 printf("bcode_decrement(%u) returns %d\n",
453 retval = ea_refcount_validate(refcount, stderr);
455 com_err("ea_refcount_validate",
458 printf("Refcount validation OK.\n");
461 ea_refcount_intr_begin(refcount);
463 blk = ea_refcount_intr_next(refcount,
467 printf("\tblk=%u, count=%d\n", blk,
472 refcount_collapse(refcount);