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, 1998 by Theodore Ts'o and
11 * Copyright (C) 1999, 2000 by Theosore Ts'o
14 * This file may be redistributed under the terms of the GNU Public
19 #include "resize2fs.h"
21 struct ext2_extent_entry {
22 __u32 old_loc, new_loc;
27 struct ext2_extent_entry *list;
35 * Create an extent table
37 errcode_t ext2fs_create_extent_table(ext2_extent *ret_extent, int size)
42 retval = ext2fs_get_mem(sizeof(struct _ext2_extent), &extent);
45 memset(extent, 0, sizeof(struct _ext2_extent));
47 extent->size = size ? size : 50;
52 retval = ext2fs_get_array(sizeof(struct ext2_extent_entry),
53 extent->size, &extent->list);
55 ext2fs_free_mem(&extent);
58 memset(extent->list, 0,
59 sizeof(struct ext2_extent_entry) * extent->size);
65 * Free an extent table
67 void ext2fs_free_extent_table(ext2_extent extent)
70 ext2fs_free_mem(&extent->list);
74 ext2fs_free_mem(&extent);
78 * Add an entry to the extent table
80 errcode_t ext2fs_add_extent_entry(ext2_extent extent, __u32 old_loc, __u32 new_loc)
82 struct ext2_extent_entry *ent;
87 if (extent->num >= extent->size) {
88 newsize = extent->size + 100;
89 retval = ext2fs_resize_mem(sizeof(struct ext2_extent_entry) *
91 sizeof(struct ext2_extent_entry) *
92 newsize, &extent->list);
95 extent->size = newsize;
98 ent = extent->list + curr;
101 * Check to see if this can be coalesced with the last
105 if ((ent->old_loc + ent->size == old_loc) &&
106 (ent->new_loc + ent->size == new_loc)) {
111 * Now see if we're going to ruin the sorting
113 if (ent->old_loc + ent->size > old_loc)
117 ent->old_loc = old_loc;
118 ent->new_loc = new_loc;
125 * Helper function for qsort
127 static EXT2_QSORT_TYPE extent_cmp(const void *a, const void *b)
129 const struct ext2_extent_entry *db_a;
130 const struct ext2_extent_entry *db_b;
132 db_a = (const struct ext2_extent_entry *) a;
133 db_b = (const struct ext2_extent_entry *) b;
135 return (db_a->old_loc - db_b->old_loc);
139 * Given an inode map and inode number, look up the old inode number
140 * and return the new inode number.
142 __u32 ext2fs_extent_translate(ext2_extent extent, __u32 old_loc)
145 __u32 lowval, highval;
148 if (!extent->sorted) {
149 qsort(extent->list, extent->num,
150 sizeof(struct ext2_extent_entry), extent_cmp);
154 high = extent->num-1;
155 while (low <= high) {
162 /* Interpolate for efficiency */
163 lowval = extent->list[low].old_loc;
164 highval = extent->list[high].old_loc;
166 if (old_loc < lowval)
168 else if (old_loc > highval)
171 range = ((float) (old_loc - lowval)) /
173 mid = low + ((int) (range * (high-low)));
176 if ((old_loc >= extent->list[mid].old_loc) &&
177 (old_loc < extent->list[mid].old_loc + extent->list[mid].size))
178 return (extent->list[mid].new_loc +
179 (old_loc - extent->list[mid].old_loc));
180 if (old_loc < extent->list[mid].old_loc)
191 void ext2fs_extent_dump(ext2_extent extent, FILE *out)
194 struct ext2_extent_entry *ent;
196 fputs(_("# Extent dump:\n"), out);
197 fprintf(out, _("#\tNum=%d, Size=%d, Cursor=%d, Sorted=%d\n"),
198 extent->num, extent->size, extent->cursor, extent->sorted);
199 for (i=0, ent=extent->list; i < extent->num; i++, ent++) {
200 fprintf(out, _("#\t\t %u -> %u (%d)\n"), ent->old_loc,
201 ent->new_loc, ent->size);
206 * Iterate over the contents of the extent table
208 errcode_t ext2fs_iterate_extent(ext2_extent extent, __u32 *old_loc,
209 __u32 *new_loc, int *size)
211 struct ext2_extent_entry *ent;
218 if (extent->cursor >= extent->num) {
225 ent = extent->list + extent->cursor++;
227 *old_loc = ent->old_loc;
228 *new_loc = ent->new_loc;