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