2 * extent.c --- ext2 extent abstraction
4 * This abstraction is used to provide a compact way of representing a
5 * translation table, for moving multiple contiguous ranges (extents)
8 * Copyright (C) 1997 Theodore Ts'o
11 * All rights reserved.
15 #include "resize2fs.h"
17 struct ext2_extent_entry {
23 struct ext2_extent_entry *list;
31 * Create an extent table
33 errcode_t ext2fs_create_extent_table(ext2_extent *ret_extent, int size)
37 new = malloc(sizeof(struct _ext2_extent));
40 memset(new, 0, sizeof(struct _ext2_extent));
42 new->size = size ? size : 50;
47 new->list = malloc(sizeof(struct ext2_extent_entry) * new->size);
52 memset(new->list, 0, sizeof(struct ext2_extent_entry) * new->size);
58 * Free an extent table
60 void ext2fs_free_extent_table(ext2_extent extent)
71 * Add an entry to the extent table
73 errcode_t ext2fs_add_extent_entry(ext2_extent extent, __u32 old, __u32 new)
75 struct ext2_extent_entry *p;
78 struct ext2_extent_entry *ent;
80 if (extent->num >= extent->size) {
81 newsize = extent->size + 100;
82 p = realloc(extent->list,
83 sizeof(struct ext2_extent_entry) * newsize);
87 extent->size = newsize;
90 ent = extent->list + curr;
93 * Check to see if this can be coalesced with the last
97 if ((ent->old + ent->size == old) &&
98 (ent->new + ent->size == new)) {
103 * Now see if we're going to ruin the sorting
105 if (ent->old + ent->size > old)
117 * Helper function for qsort
119 static int extent_cmp(const void *a, const void *b)
121 const struct ext2_extent_entry *db_a = a;
122 const struct ext2_extent_entry *db_b = b;
124 return (db_a->old - db_b->old);
128 * Given an inode map and inode number, look up the old inode number
129 * and return the new inode number
131 __u32 ext2fs_extent_translate(ext2_extent extent, __u32 old)
134 ino_t lowval, highval;
137 if (!extent->sorted) {
138 qsort(extent->list, extent->num,
139 sizeof(struct ext2_extent_entry), extent_cmp);
143 high = extent->num-1;
144 while (low <= high) {
151 /* Interpolate for efficiency */
152 lowval = extent->list[low].old;
153 highval = extent->list[high].old;
157 else if (old > highval)
160 range = ((float) (old - lowval)) /
162 mid = low + ((int) (range * (high-low)));
165 if ((old >= extent->list[mid].old) &&
166 (old < extent->list[mid].old + extent->list[mid].size))
167 return (extent->list[mid].new +
168 (old - extent->list[mid].old));
169 if (old < extent->list[mid].old)
180 void ext2fs_extent_dump(ext2_extent extent, FILE *out)
183 struct ext2_extent_entry *ent;
185 fputs("# Extent dump:\n", out);
186 fprintf(out, "#\tNum=%d, Size=%d, Cursor=%d, Sorted=%d\n",
187 extent->num, extent->size, extent->cursor, extent->sorted);
188 for (i=0, ent=extent->list; i < extent->num; i++, ent++) {
189 fprintf(out, "#\t\t %u -> %u (%d)\n", ent->old,
190 ent->new, ent->size);
195 * Iterate over the contents of the extent table
197 errcode_t ext2fs_iterate_extent(ext2_extent extent, __u32 *old,
198 __u32 *new, int *size)
200 struct ext2_extent_entry *ent;
207 if (extent->cursor >= extent->num) {
214 ent = extent->list + extent->cursor++;