/*
* ea_refcount.c
*
* Copyright (C) 2001 Theodore Ts'o. This file may be
* redistributed under the terms of the GNU Public License.
*/
#if HAVE_UNISTD_H
#include <unistd.h>
#endif
#include <string.h>
#include <stdio.h>
#include "e2fsck.h"
/*
* The strategy we use for keeping track of EA refcounts is as
* follows. We keep a sorted array of first EA blocks and its
* reference counts. Once the refcount has dropped to zero, it is
* removed from the array to save memory space. Once the EA block is
* checked, its bit is set in the block_ea_map bitmap.
*/
struct ea_refcount_el {
blk_t ea_blk;
int ea_count;
};
struct ea_refcount {
blk_t count;
blk_t size;
blk_t cursor;
struct ea_refcount_el *list;
};
void ea_refcount_free(ext2_refcount_t refcount)
{
if (!refcount)
return;
if (refcount->list)
ext2fs_free_mem(&refcount->list);
ext2fs_free_mem(&refcount);
}
errcode_t ea_refcount_create(int size, ext2_refcount_t *ret)
{
ext2_refcount_t refcount;
errcode_t retval;
size_t bytes;
retval = ext2fs_get_mem(sizeof(struct ea_refcount), &refcount);
if (retval)
return retval;
memset(refcount, 0, sizeof(struct ea_refcount));
if (!size)
size = 500;
refcount->size = size;
bytes = (size_t) (size * sizeof(struct ea_refcount_el));
#ifdef DEBUG
printf("Refcount allocated %d entries, %d bytes.\n",
refcount->size, bytes);
#endif
retval = ext2fs_get_mem(bytes, &refcount->list);
if (retval)
goto errout;
memset(refcount->list, 0, bytes);
refcount->count = 0;
refcount->cursor = 0;
*ret = refcount;
return 0;
errout:
ea_refcount_free(refcount);
return(retval);
}
/*
* collapse_refcount() --- go through the refcount array, and get rid
* of any count == zero entries
*/
static void refcount_collapse(ext2_refcount_t refcount)
{
unsigned int i, j;
struct ea_refcount_el *list;
list = refcount->list;
for (i = 0, j = 0; i < refcount->count; i++) {
if (list[i].ea_count) {
if (i != j)
list[j] = list[i];
j++;
}
}
#if defined(DEBUG) || defined(TEST_PROGRAM)
printf("Refcount_collapse: size was %d, now %d\n",
refcount->count, j);
#endif
refcount->count = j;
}
/*
* insert_refcount_el() --- Insert a new entry into the sorted list at a
* specified position.
*/
static struct ea_refcount_el *insert_refcount_el(ext2_refcount_t refcount,
blk_t blk, int pos)
{
struct ea_refcount_el *el;
errcode_t retval;
blk_t new_size = 0;
int num;
if (refcount->count >= refcount->size) {
new_size = refcount->size + 100;
#ifdef DEBUG
printf("Reallocating refcount %d entries...\n", new_size);
#endif
retval = ext2fs_resize_mem((size_t) refcount->size *
sizeof(struct ea_refcount_el),
(size_t) new_size *
sizeof(struct ea_refcount_el),
&refcount->list);
if (retval)
return 0;
refcount->size = new_size;
}
num = (int) refcount->count - pos;
if (num < 0)
return 0; /* should never happen */
if (num) {
memmove(&refcount->list[pos+1], &refcount->list[pos],
sizeof(struct ea_refcount_el) * num);
}
refcount->count++;
el = &refcount->list[pos];
el->ea_count = 0;
el->ea_blk = blk;
return el;
}
/*
* get_refcount_el() --- given an block number, try to find refcount
* information in the sorted list. If the create flag is set,
* and we can't find an entry, create one in the sorted list.
*/
static struct ea_refcount_el *get_refcount_el(ext2_refcount_t refcount,
blk_t blk, int create)
{
float range;
int low, high, mid;
blk_t lowval, highval;
if (!refcount || !refcount->list)
return 0;
retry:
low = 0;
high = (int) refcount->count-1;
if (create && ((refcount->count == 0) ||
(blk > refcount->list[high].ea_blk))) {
if (refcount->count >= refcount->size)
refcount_collapse(refcount);
return insert_refcount_el(refcount, blk,
(unsigned) refcount->count);
}
if (refcount->count == 0)
return 0;
if (refcount->cursor >= refcount->count)
refcount->cursor = 0;
if (blk == refcount->list[refcount->cursor].ea_blk)
return &refcount->list[refcount->cursor++];
#ifdef DEBUG
printf("Non-cursor get_refcount_el: %u\n", blk);
#endif
while (low <= high) {
#if 0
mid = (low+high)/2;
#else
if (low == high)
mid = low;
else {
/* Interpolate for efficiency */
lowval = refcount->list[low].ea_blk;
highval = refcount->list[high].ea_blk;
if (blk < lowval)
range = 0;
else if (blk > highval)
range = 1;
else
range = ((float) (blk - lowval)) /
(highval - lowval);
mid = low + ((int) (range * (high-low)));
}
#endif
if (blk == refcount->list[mid].ea_blk) {
refcount->cursor = mid+1;
return &refcount->list[mid];
}
if (blk < refcount->list[mid].ea_blk)
high = mid-1;
else
low = mid+1;
}
/*
* If we need to create a new entry, it should be right at
* low (where high will be left at low-1).
*/
if (create) {
if (refcount->count >= refcount->size) {
refcount_collapse(refcount);
if (refcount->count < refcount->size)
goto retry;
}
return insert_refcount_el(refcount, blk, low);
}
return 0;
}
errcode_t ea_refcount_fetch(ext2_refcount_t refcount, blk_t blk,
int *ret)
{
struct ea_refcount_el *el;
el = get_refcount_el(refcount, blk, 0);
if (!el) {
*ret = 0;
return 0;
}
*ret = el->ea_count;
return 0;
}
errcode_t ea_refcount_increment(ext2_refcount_t refcount, blk_t blk, int *ret)
{
struct ea_refcount_el *el;
el = get_refcount_el(refcount, blk, 1);
if (!el)
return EXT2_ET_NO_MEMORY;
el->ea_count++;
if (ret)
*ret = el->ea_count;
return 0;
}
errcode_t ea_refcount_decrement(ext2_refcount_t refcount, blk_t blk, int *ret)
{
struct ea_refcount_el *el;
el = get_refcount_el(refcount, blk, 0);
if (!el || el->ea_count == 0)
return EXT2_ET_INVALID_ARGUMENT;
el->ea_count--;
if (ret)
*ret = el->ea_count;
return 0;
}
errcode_t ea_refcount_store(ext2_refcount_t refcount, blk_t blk, int count)
{
struct ea_refcount_el *el;
/*
* Get the refcount element
*/
el = get_refcount_el(refcount, blk, count ? 1 : 0);
if (!el)
return count ? EXT2_ET_NO_MEMORY : 0;
el->ea_count = count;
return 0;
}
blk_t ext2fs_get_refcount_size(ext2_refcount_t refcount)
{
if (!refcount)
return 0;
return refcount->size;
}
void ea_refcount_intr_begin(ext2_refcount_t refcount)
{
refcount->cursor = 0;
}
blk_t ea_refcount_intr_next(ext2_refcount_t refcount,
int *ret)
{
struct ea_refcount_el *list;
while (1) {
if (refcount->cursor >= refcount->count)
return 0;
list = refcount->list;
if (list[refcount->cursor].ea_count) {
if (ret)
*ret = list[refcount->cursor].ea_count;
return list[refcount->cursor++].ea_blk;
}
refcount->cursor++;
}
}
#ifdef TEST_PROGRAM
errcode_t ea_refcount_validate(ext2_refcount_t refcount, FILE *out)
{
errcode_t ret = 0;
int i;
const char *bad = "bad refcount";
if (refcount->count > refcount->size) {
fprintf(out, "%s: count > size\n", bad);
return EXT2_ET_INVALID_ARGUMENT;
}
for (i=1; i < refcount->count; i++) {
if (refcount->list[i-1].ea_blk >= refcount->list[i].ea_blk) {
fprintf(out, "%s: list[%d].blk=%u, list[%d].blk=%u\n",
bad, i-1, refcount->list[i-1].ea_blk,
i, refcount->list[i].ea_blk);
ret = EXT2_ET_INVALID_ARGUMENT;
}
}
return ret;
}
#define BCODE_END 0
#define BCODE_CREATE 1
#define BCODE_FREE 2
#define BCODE_STORE 3
#define BCODE_INCR 4
#define BCODE_DECR 5
#define BCODE_FETCH 6
#define BCODE_VALIDATE 7
#define BCODE_LIST 8
#define BCODE_COLLAPSE 9
int bcode_program[] = {
BCODE_CREATE, 5,
BCODE_STORE, 3, 3,
BCODE_STORE, 4, 4,
BCODE_STORE, 1, 1,
BCODE_STORE, 8, 8,
BCODE_STORE, 2, 2,
BCODE_STORE, 4, 0,
BCODE_STORE, 2, 0,
BCODE_STORE, 6, 6,
BCODE_VALIDATE,
BCODE_STORE, 4, 4,
BCODE_STORE, 2, 2,
BCODE_FETCH, 1,
BCODE_FETCH, 2,
BCODE_INCR, 3,
BCODE_INCR, 3,
BCODE_DECR, 4,
BCODE_STORE, 4, 4,
BCODE_VALIDATE,
BCODE_STORE, 20, 20,
BCODE_STORE, 40, 40,
BCODE_STORE, 30, 30,
BCODE_STORE, 10, 10,
BCODE_DECR, 30,
BCODE_FETCH, 30,
BCODE_DECR, 2,
BCODE_DECR, 2,
BCODE_COLLAPSE,
BCODE_LIST,
BCODE_VALIDATE,
BCODE_FREE,
BCODE_END
};
int main(int argc, char **argv)
{
int i = 0;
ext2_refcount_t refcount;
int size, arg;
blk_t blk;
errcode_t retval;
while (1) {
switch (bcode_program[i++]) {
case BCODE_END:
exit(0);
case BCODE_CREATE:
size = bcode_program[i++];
retval = ea_refcount_create(size, &refcount);
if (retval) {
com_err("ea_refcount_create",
retval, "");
exit(1);
} else
printf("Creating refcount with size %d\n",
size);
break;
case BCODE_FREE:
ea_refcount_free(refcount);
refcount = 0;
printf("Freeing refcount\n");
break;
case BCODE_STORE:
blk = (blk_t) bcode_program[i++];
arg = bcode_program[i++];
retval = ea_refcount_store(refcount, blk, arg);
printf("Storing blk %u with value %d\n", blk, arg);
if (retval)
com_err("ea_refcount_store", retval, "");
break;
case BCODE_FETCH:
blk = (blk_t) bcode_program[i++];
retval = ea_refcount_fetch(refcount, blk, &arg);
if (retval)
com_err("ea_refcount_fetch", retval, "");
else
printf("bcode_fetch(%u) returns %d\n",
blk, arg);
break;
case BCODE_INCR:
blk = (blk_t) bcode_program[i++];
retval = ea_refcount_increment(refcount, blk,
&arg);
if (retval)
com_err("ea_refcount_increment", retval,
"");
else
printf("bcode_increment(%u) returns %d\n",
blk, arg);
break;
case BCODE_DECR:
blk = (blk_t) bcode_program[i++];
retval = ea_refcount_decrement(refcount, blk,
&arg);
if (retval)
com_err("ea_refcount_decrement", retval,
"while decrementing blk %u", blk);
else
printf("bcode_decrement(%u) returns %d\n",
blk, arg);
break;
case BCODE_VALIDATE:
retval = ea_refcount_validate(refcount, stderr);
if (retval)
com_err("ea_refcount_validate",
retval, "");
else
printf("Refcount validation OK.\n");
break;
case BCODE_LIST:
ea_refcount_intr_begin(refcount);
while (1) {
blk = ea_refcount_intr_next(refcount,
&arg);
if (!blk)
break;
printf("\tblk=%u, count=%d\n", blk,
arg);
}
break;
case BCODE_COLLAPSE:
refcount_collapse(refcount);
break;
}
}
}
#endif